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Sample records for l-alanine difracao multipla

  1. Vibrational dynamics of crystalline L-alanine

    SciTech Connect

    Bordallo, H.N.; Eckert, J.; Barthes, M.

    1997-11-01

    The authors report a new, complete vibrational analysis of L-alanine and L-alanine-d{sub 4} which utilizes IINS intensities in addition to frequency information. The use of both isotopomers resulted in a self-consistent force field for and assignment of the molecular vibrations in L-alanine. Some details of the calculation as well as a comparison of calculated and observed IINS spectra are presented. The study clarifies a number of important issues on the vibrational dynamics of this molecule and presents a self-consistent force field for the molecular vibrations in crystalline L-alanine.

  2. On the existence of ‘L-alanine cadmium bromide'

    NASA Astrophysics Data System (ADS)

    Srinivasan, Bikshandarkoil R.

    2013-12-01

    It is argued that the recently reported nonlinear optical crystal L-alanine cadmium bromide, grown by slow solvent evaporation method at room temperature [P. Ilayabarathi, J. Chandrasekaran, Spectrochim. Acta 96A (2012) 684-689] is the well-known L-alanine crystal. The isolation of L-alanine crystal is explained due to fractional crystallization.

  3. On the existence of 'L-alanine cadmium bromide'.

    PubMed

    Srinivasan, Bikshandarkoil R

    2013-12-01

    It is argued that the recently reported nonlinear optical crystal L-alanine cadmium bromide, grown by slow solvent evaporation method at room temperature [P. Ilayabarathi, J. Chandrasekaran, Spectrochim. Acta 96A (2012) 684-689] is the well-known L-alanine crystal. The isolation of L-alanine crystal is explained due to fractional crystallization.

  4. Atomic Layer Deposition of L-Alanine Polypeptide

    SciTech Connect

    Fu, Yaqin; Li, Binsong; Jiang, Ying-Bing; Dunphy, Darren R.; Tsai, Andy; Tam, Siu-Yue; Fan, Hongyou Y.; Zhang, Hongxia; Rogers, David; Rempe, Susan; Atanassov, Plamen; Cecchi, Joseph L.; Brinker, C. Jeffrey

    2014-10-30

    L-Alanine polypeptide thin films were synthesized via atomic layer deposition (ALD). Rather, instead of using an amino acid monomer as the precursor, an L-alanine amino acid derivatized with a protecting group was used to prevent self-polymerization, increase the vapor pressure, and allow linear cycle-by-cycle growth emblematic of ALD. Moreover, the successful deposition of a conformal polypeptide film has been confirmed by FTIR, TEM, and Mass Spectrometry, and the ALD process has been extended to polyvaline.

  5. On the existence of ``l-threonine formate'', ``l-alanine lithium chloride'' and ``bis l-alanine lithium chloride'' crystals

    NASA Astrophysics Data System (ADS)

    Petrosyan, A. M.; Ghazaryan, V. V.; Fleck, M.

    2013-03-01

    We argue that the recently reported crystals "L-threonine formate" as well as "L-alanine lithium chloride" and "bis L-alanine lithium chloride" actually are the well-known crystals L-threonine and L-alanine, respectively.

  6. First principles investigation of L-alanine in terahertz region.

    PubMed

    Zheng, Zhuan-Ping; Fan, Wen-Hui

    2012-06-01

    Terahertz absorption spectrum (0.5-4.0 THz) of L-alanine in the solid phase was measured by terahertz time-domain spectroscopy at room temperature. Simulations utilizing gaseous-state and solid-state theory were performed to determine the origins of the observed vibrational features. Our calculations showed that the measured features in solid-state materials could be well understood by considering the crystal packing interactions in a solid-state density functional theory calculation. Furthermore, intermolecular vibrations of L-alanine are found to be the dominating contributions to these measured spectral features in the range of 0.5-4.0 THz, except that located at 3.11 THz.

  7. Pressure-induced phase transitions in L-alanine, revisited.

    PubMed

    Tumanov, N A; Boldyreva, E V; Kolesov, B A; Kurnosov, A V; Quesada Cabrera, R

    2010-08-01

    The effect of pressure on L-alanine has been studied by X-ray powder diffraction (up to 12.3 GPa), single-crystal X-ray diffraction, Raman spectroscopy and optical microscopy (up to approximately 6 GPa). No structural phase transitions have been observed. At approximately 2 GPa the cell parameters a and b become accidentally equal to each other, but without a change in space-group symmetry. Neither of two transitions reported by others (to a tetragonal phase at approximately 2 GPa and to a monoclinic phase at approximately 9 GPa) was observed. The changes in cell parameters were continuous up to the highest measured pressures and the cells remained orthorhombic. Some important changes in the intermolecular interactions occur, which also manifest themselves in the Raman spectra. Two new orthorhombic phases could be crystallized from a MeOH/EtOH/H(2)O pressure-transmitting mixture in the pressure range 0.8-4.7 GPa, but only if the sample was kept at these pressures for at least 1-2 d. The new phases converted back to L-alanine on decompression. Judging from the Raman spectra and cell parameters, the new phases are most probably not L-alanine but its solvates.

  8. Isotopic effects in mechanistic studies of biotransformations of fluorine derivatives of L-alanine catalysed by L-alanine dehydrogenase.

    PubMed

    Szymańska-Majchrzak, Jolanta; Pałka, Katarzyna; Kańska, Marianna

    2017-05-01

    Synthesis of 3-fluoro-[2-(2)H]-L-alanine (3-F-[(2)H]-L-Ala) in reductive amination of 3-fluoropyruvic acid catalysed by L-alanine dehydrogenase (AlaDH) was described. Fluorine derivative was used to study oxidative deamination catalysed by AlaDH applied kinetic (for 3-F-L-Ala in H2O - KIE's on Vmax: 1.1; on Vmax/KM: 1.2; for 3-F-L-Ala in (2)H2O - on Vmax: 1.4; on Vmax/KM: 2.1) and solvent isotope effect methods (for 3-F-L-Ala - SIE's on Vmax: 1.0; on Vmax/KM: 0.87; for 3-F-[2-(2)H]-L-Ala - on Vmax: 1.4; on Vmax/KM: 1.5). Studies explain some details of reaction mechanism. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. l-Alanine Auxotrophy of Lactobacillus johnsonii as Demonstrated by Physiological, Genomic, and Gene Complementation Approaches

    PubMed Central

    van der Kaaij, Hengameh; Desiere, Frank; Mollet, Beat; Germond, Jacques-Edouard

    2004-01-01

    Using a chemically defined medium without l-alanine, Lactobacillus johnsonii was demonstrated to be strictly auxotrophic for that amino acid. A comparative genetic analysis showed that all known genes involved in l-alanine biosynthesis are absent from the genome of L. johnsonii. This auxotrophy was complemented by heterologous expression of the Bacillus subtilis l-alanine dehydrogenase. PMID:15006820

  10. First-principles study of fluorination of L-Alanine

    NASA Astrophysics Data System (ADS)

    Sreepad, H. R.; Ravi, H. R.; Ahmed, Khaleel; Dayananda, H. M.; Umakanth, K.; Manohara, B. M.

    2013-02-01

    First-principles calculations based on Density Functional Theory have been done on effect of fluorination of an important amino acid - L-Alanine. Its structure has been simulated. The unit cell is orthorhombic with lattice parameters a=5.90Å, b=13.85Å and c=5.75Å with volume 470 (Å)3. Bond lengths and bond angles have been estimated. Electronic Density of States calculations show that the material has a band gap of 4.47eV. Electronic band structure indicates that the material can be effectively used for NLO applications. The electronic contribution to the dielectric constant has been calculated and its average value comes out to be 2.165.

  11. [Regulation of key enzymes of L-alanine biosynthesis by Brevibacterium flavum producer strains].

    PubMed

    Melkonian, L O; Avetisova, G E; Ambartsumian, A A; Chakhalian, A Kh; Sagian, A S

    2013-01-01

    The mechanisms of L-alanine overproduction by Brevibacterium flavum producer strains were studied. It was shown that beta-CI-L-alanine is an inhibitor of some key enzymes involved in the synthesis of L-alanine, including alanine transaminase and valine-pyruvate transaminase. Two highly active B. flavum GL1 and GL1 8 producer strains, which are resistant to the inhibitory effect of beta-Cl-L-alanine, were obtained using a parental B. flavum AA5 producer strain, characterized by a reduced activity of alanine racemase (>or=98%). It was demonstrated that the increased L-alanine synthesis efficiency observed in the producer strains developed in this work is associated with the absence of inhibition of alanine transaminase by the end product of the biosynthesis reaction, as well as with the effect of derepression of both alanine transaminase and valine-pyruvate transaminase synthesis by the studied compound.

  12. Synthesis and GGCT Inhibitory Activity of N-Glutaryl-L-alanine Analogues.

    PubMed

    Ii, Hiromi; Yoshiki, Tatsuhiro; Hoshiya, Naoyuki; Uenishi, Jun'ichi

    2016-01-01

    γ-Glutamylcyclotransferase (GGCT) is an important enzyme that cleaves γ-glutamyl-amino acid in the γ-glutamyl cycle to release 5-oxoproline and amino acid. Eighteen N-acyl-L-alanine analogues including eleven new compounds have been synthesized and examined for their inhibitory activity against recombinant human GGCT protein. Simple N-glutaryl-L-alanine was found to be the most potent inhibitor for GGCT. Other N-glutaryl-L-alanine analogues having methyl and dimethyl substituents at the 2-position were moderately effective, while N-(3R-aminoglutary)-L-alanine, the substrate having an (R)-amino group at the 3-position or N-(N-methyl-3-azaglutaryl)-L-alanine, the substrate having an N-methyl substituent on the 3-azaglutaryl carbon, in constract, exhibited excellent inhibition properties.

  13. Development of a prodrug of salicylic acid, salicylic acid-L-alanine conjugate, utilizing hydrolysis by rabbit intestinal microorganisms.

    PubMed

    Nakamura, J; Tagami, C; Nishida, K; Sasaki, H

    1992-04-01

    The hydrolysis of salicylic acid-L-alanine conjugate (salicyl-L-alanine) following oral, intravenous, intracaecal and rectal administration (60, 10, 5 and 5 mg kg-1, respectively: salicylic acid equivalent) was examined in rabbits. Salicylic acid was detected in the blood 2 h after oral administration of salicyl-L-alanine and reached a maximum concentration at 10 h, whereas salicyl-L-alanine was rapidly eliminated. In contrast, unchanged salicyl-L-alanine only was found following intravenous administration of salicyl-L-alanine, suggesting that presystemic de-conjugation of salicyl-L-alanine was involved. The intestinal mucosal de-conjugation of salicyl-L-alanine was not recognized in the in-situ intestinal sac preparation with complete mesenteric venous blood collection. Immediate and very extensive salicylic acid formation in the caecum was found following intracaecal administration of salicyl-L-alanine. After oral pretreatment of rabbits with kanamycin sulphate, a significant inhibition of salicylic acid formation following intracaecal administration of salicyl-L-alanine was observed, indicating that the intestinal microorganisms were responsible for the biotransformation of salicyl-L-alanine. In-vitro incubation of salicyl-L-alanine with gut contents showed that the major source of its hydrolysis was the hind gut. Consequently, the blood concentration of salicylic acid was prolonged extensively following rectal administration of salicyl-L-alanine, suggesting the usefulness of salicyl-L-alanine as a prodrug of salicylic acid.

  14. Impact of charged amino acid substitution in the transmembrane domain of L-alanine exporter, AlaE, of Escherichia coli on the L-alanine export.

    PubMed

    Kim, Seryoung; Ihara, Kohei; Katsube, Satoshi; Ando, Tasuke; Isogai, Emiko; Yoneyama, Hiroshi

    2017-01-01

    The Escherichia coli alaE gene encodes the L-alanine exporter, AlaE, that catalyzes active export of L-alanine using proton electrochemical potential. The transporter comprises only 149 amino acid residues and four predicted transmembrane domains (TMs), which contain three charged amino acid residues. The AlaE-deficient L-alanine non-metabolizing cells (ΔalaE cells) appeared hypersusceptible to L-alanyl-L-alanine showing a minimum inhibitory concentration (MIC) of 2.5 µg/ml for the dipeptide due to a toxic accumulation of L-alanine. To elucidate the mechanism by which AlaE exports L-alanine, we replaced charged amino acid residues in the TMs, glutamic acid-30 (TM-I), arginine-45 (TM-II), and aspartic acid-84 (TM-III) with their respective charge-conserved amino acid or a net neutral cysteine. The ΔalaE cells producing R45K or R45C appeared hypersusceptible to the dipeptide, indicating that arginine-45 is essential for AlaE activity. MIC of the dipeptide in the ΔalaE cells expressing E30D and E30C was 156 µg/ml and >10,000 µg/ml, respectively, thereby suggesting that a negative charge at this position is not essential. The ΔalaE cells expressing D84E or D84C showed an MIC >10,000 and 78 µg/ml, respectively, implying that a negative charge is required at this position. These results were generally consistent with that of the L-alanine accumulation experiments in intact cells. We therefore concluded that charged amino acid residues (R45 and D84) in the AlaE transmembrane domain play a pivotal role in L-alanine export. Replacement of three cysteine residues at C22, C28 (both in TM-I), and C135 (C-terminal region) with alanine showed only a marginal effect on L-alanine export.

  15. Efficient L-Alanine Production by a Thermo-Regulated Switch in Escherichia coli.

    PubMed

    Zhou, Li; Deng, Can; Cui, Wen-Jing; Liu, Zhong-Mei; Zhou, Zhe-Min

    2016-01-01

    L-Alanine has important applications in food, pharmaceutical and veterinary and is used as a substrate for production of engineered thermoplastics. Microbial fermentation could reduce the production cost and promote the application of L-alanine. However, the presence of L-alanine significantly inhibit cell growth rate and cause a decrease in the ultimate L-alanine productivity. For efficient L-alanine production, a thermo-regulated genetic switch was designed to dynamically control the expression of L-alanine dehydrogenase (alaD) from Geobacillus stearothermophilus on the Escherichia coli B0016-060BC chromosome. The optimal cultivation conditions for the genetically switched alanine production using B0016-060BC were the following: an aerobic growth phase at 33 °C with a 1-h thermo-induction at 42 °C followed by an oxygen-limited phase at 42 °C. In a bioreactor experiment using the scaled-up conditions optimized in a shake flask, B0016-060BC accumulated 50.3 g biomass/100 g glucose during the aerobic growth phase and 96 g alanine/100 g glucose during the oxygen-limited phase, respectively. The L-alanine titer reached 120.8 g/l with higher overall and oxygen-limited volumetric productivities of 3.09 and 4.18 g/l h, respectively, using glucose as the sole carbon source. Efficient cell growth and L-alanine production were reached separately, by switching cultivation temperature. The results revealed the application of a thermo-regulated strategy for heterologous metabolic production and pointed to strategies for improving L-alanine production.

  16. Temperature dependences of piezoelectric, elastic and dielectric constants of L-alanine crystal

    NASA Astrophysics Data System (ADS)

    Tylczyński, Z.; Sterczyńska, A.; Wiesner, M.

    2011-09-01

    Temperature changes in the components of piezoelectric, elastic and dielectric tensors were studied in L-alanine crystals in the range 100-300 K. A jumpwise increase in the c55 component of the elastic stiffness accompanied by maxima in damping of all face-shear modes observed at 199 K in L-alanine crystal were interpreted as a result of changes in the NH3+ vibrations occurring through electron-phonon coupling. All components of the piezoelectric tensor show small anomalies in this temperature range. The components of the electromechanical coupling coefficient determined indicate that L-alanine is a weak piezoelectric.

  17. Temperature dependences of piezoelectric, elastic and dielectric constants of L-alanine crystal.

    PubMed

    Tylczyński, Z; Sterczyńska, A; Wiesner, M

    2011-09-07

    Temperature changes in the components of piezoelectric, elastic and dielectric tensors were studied in L-alanine crystals in the range 100-300 K. A jumpwise increase in the c(55) component of the elastic stiffness accompanied by maxima in damping of all face-shear modes observed at 199 K in L-alanine crystal were interpreted as a result of changes in the NH(3)(+) vibrations occurring through electron-phonon coupling. All components of the piezoelectric tensor show small anomalies in this temperature range. The components of the electromechanical coupling coefficient determined indicate that L-alanine is a weak piezoelectric.

  18. A comparative study on the growth and characterization of nonlinear optical amino acid crystals: L-alanine (LA) and L-alanine alaninium nitrate (LAAN).

    PubMed

    Aravindan, A; Srinivasan, P; Vijayan, N; Gopalakrishnan, R; Ramasamy, P

    2008-11-15

    A comparative study on the properties of L-alanine and LAAN crystals has been made and discussed. It may be concluded that the protonation of the amino group in the L-alanine molecule is the key factor in increasing the relative SHG efficiency of LAAN. The protonation is justified by the crystal structure analysis, FTIR and photoluminescence studies. The factor group vibrations are compared and found that there is an increase in vibrational modes of LA when reacted with nitric acid forming LAAN.

  19. Characterization of the l-alanine exporter AlaE of Escherichia coli and its potential role in protecting cells from a toxic-level accumulation of l-alanine and its derivatives.

    PubMed

    Kim, Seryoung; Ihara, Kohei; Katsube, Satoshi; Hori, Hatsuhiro; Ando, Tasuke; Isogai, Emiko; Yoneyama, Hiroshi

    2015-08-01

    We previously reported that the alaE gene of Escherichia coli encodes the l-alanine exporter AlaE. The objective of this study was to elucidate the mechanism of the AlaE exporter. The minimum inhibitory concentration of l-alanine and l-alanyl-l-alanine in alaE-deficient l-alanine-nonmetabolizing cells MLA301ΔalaE was 4- and >4000-fold lower, respectively, than in the alaE-positive parent cells MLA301, suggesting that AlaE functions as an efflux pump to avoid a toxic-level accumulation of intracellular l-alanine and its derivatives. Furthermore, the growth of the alaE-deficient mutant derived from the l-alanine-metabolizing strain was strongly inhibited in the presence of a physiological level of l-alanyl-l-alanine. Intact MLA301ΔalaE and MLA301ΔalaE/pAlaE cells producing plasmid-borne AlaE, accumulated approximately 200% and 50%, respectively, of the [(3) H]l-alanine detected in MLA301 cells, suggesting that AlaE exports l-alanine. When 200 mmol/L l-alanine-loaded inverted membrane vesicles prepared from MLA301ΔalaE/pAlaE were placed in a solution containing 200 mmol/L or 0.34 μmol/L l-alanine, energy-dependent [(3) H]l-alanine accumulation occurred under either condition. This energy-dependent uphill accumulation of [(3) H]l-alanine was strongly inhibited in the presence of carbonyl cyanide m-chlorophenylhydrazone but not by dicyclohexylcarbodiimide, suggesting that the AlaE-mediated l-alanine extrusion was driven by proton motive force. Based on these results, physiological roles of the l-alanine exporter are discussed.

  20. Characterization of the l-alanine exporter AlaE of Escherichia coli and its potential role in protecting cells from a toxic-level accumulation of l-alanine and its derivatives

    PubMed Central

    Kim, Seryoung; Ihara, Kohei; Katsube, Satoshi; Hori, Hatsuhiro; Ando, Tasuke; Isogai, Emiko; Yoneyama, Hiroshi

    2015-01-01

    We previously reported that the alaE gene of Escherichia coli encodes the l-alanine exporter AlaE. The objective of this study was to elucidate the mechanism of the AlaE exporter. The minimum inhibitory concentration of l-alanine and l-alanyl-l-alanine in alaE-deficient l-alanine-nonmetabolizing cells MLA301ΔalaE was 4- and >4000-fold lower, respectively, than in the alaE-positive parent cells MLA301, suggesting that AlaE functions as an efflux pump to avoid a toxic-level accumulation of intracellular l-alanine and its derivatives. Furthermore, the growth of the alaE-deficient mutant derived from the l-alanine-metabolizing strain was strongly inhibited in the presence of a physiological level of l-alanyl-l-alanine. Intact MLA301ΔalaE and MLA301ΔalaE/pAlaE cells producing plasmid-borne AlaE, accumulated approximately 200% and 50%, respectively, of the [3H]l-alanine detected in MLA301 cells, suggesting that AlaE exports l-alanine. When 200 mmol/L l-alanine-loaded inverted membrane vesicles prepared from MLA301ΔalaE/pAlaE were placed in a solution containing 200 mmol/L or 0.34 μmol/L l-alanine, energy-dependent [3H]l-alanine accumulation occurred under either condition. This energy-dependent uphill accumulation of [3H]l-alanine was strongly inhibited in the presence of carbonyl cyanide m-chlorophenylhydrazone but not by dicyclohexylcarbodiimide, suggesting that the AlaE-mediated l-alanine extrusion was driven by proton motive force. Based on these results, physiological roles of the l-alanine exporter are discussed. PMID:26073055

  1. Second harmonic generation studies in L-alanine single crystals grown from solution

    NASA Astrophysics Data System (ADS)

    Boomadevi, Shanmugam; Pandiyan, Krishnamoorthy

    2014-01-01

    Single crystals of L-alanine of dimensions 2×1.1×0.5 cm3 were grown by evaporation method using deionised water as a solvent. The morphology of the grown crystals had (1 2 0) and (0 1 1) as their prominent faces. UV-vis-near IR spectrum shows the transparency range of L-alanine crystal available for frequency doubling from 250 to 1400 nm. Phase-matched second harmonic generation was observed in L-alanine sample by using 7 ns Q-switched Nd:YAG laser with OPO set up. In the present work, phase matching was achieved by angle and wavelength tuning. The angular and spectral phase-matching bandwidths were determined experimentally for a 1.5 mm thick L-alanine crystal and the results have been compared with their theoretical results. Further the possible reasons for the broadening of SHG spectrum have been discussed.

  2. Interactions of L-alanine with alumina as studied by vibrational spectroscopy.

    PubMed

    Garcia, Ana R; de Barros, Ricardo Brito; Fidalgo, Alexandra; Ilharco, Laura M

    2007-09-25

    The interactions of L-alanine with gamma- and alpha-alumina have been investigated by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). L-alanine/alumina samples were dried from aqueous suspensions, at 36.5 degrees C, with two amino acid concentrations (0.4 and 0.8 mmol g-1) and at different pH values (1, 6, and 13). The vibrational spectra proved that the nature of L-alanine interactions with both aluminas is the same (hydrogen bonding), although the groups involved depend on the L-alanine form and on alumina surface groups, both controlled by the pH. For samples prepared at pH 1, cationic L-alanine [CH3CH(NH3+)COOH] displaces physisorbed water from alumina, and strong hydrogen bonds are established between the carbonyl groups of alanine, as electron donors, and the surface Al-OH2+ groups of alumina. This occurs at the expense of alanine dimer dissociation and breaking of intramolecular bonds. When samples are prepared at pH 6, the interacting groups are Al-OH2+ and the carboxylate groups of zwitterionic L-alanine [CH3CH(NH3+)COO-]. The affinity of L-alanine toward alumina decreases, as the strong NH3+...-OOC intermolecular hydrogen bonds prevail over the interactions with alumina. Thus, for a load of 0.8 mmol g-1, phase segregation is observed. On alpha-alumina, crystal deposition is even observed for a load of 0.4 mmol g-1. At pH 13, the carboxylate groups of anionic L-alanine [CH3CH(NH2)COO-] are not affected by alumina. Instead, hydrogen bond interactions occur between NH2 and the Al-OH surface groups of the substrate. Complementary N2 adsorption-desorption isotherms showed that adsorption of L-alanine occurs onto the alumina pore network for samples prepared at pH 1 and 13, whereas at pH 6 the amino acid/alumina interactions are not strong enough to promote adsorption. The mesoporous structure and the high specific surface area of gamma-alumina make it a more efficient substrate for adsorption of L-alanine. For each alumina, however, it is

  3. Determination of D- and L-alanine concentrations using a pyruvic acid sensor.

    PubMed

    Inaba, Yohei; Hamada-Sato, Naoko; Kobayashi, Takeshi; Imada, Chiaki; Watanabe, Etsuo

    2003-08-01

    The concentrations of D- and L-alanine in bivalves are useful as indicators of environmental pollution. Amino acid oxidase with a low substrate specificity catalyzes the oxidation of various amino acids. Among the various amino acids, pyruvic acid can be generated from alanine only by the catalytic oxidative reaction of this oxidase. Therefore, in this study, the concentrations of D- and L-alanine were determined from the concentration of pyruvic acid, which was determined from the consumption of oxygen based on the oxidative reaction of pyruvate oxidase. From this point of view, there is a very strong possibility that biosensors utilizing enzymes with a low substrate specificity can be developed. The results obtained were as follows. (1) The optimum conditions for the use of pyruvic acid sensor were as follows: temperature of 25 degrees C, pH of 6.8, flow rate of 0.1 ml/min, thiamin diphosphate concentration of 1.5 mM, and injection volume of 50 microl. (2) D-Alanine and L-alanine optimally reacted with D- and L-amino acid oxidase at 30 degrees C, pH 8.2, for 30 min and at 37 degrees C, pH 7.8, for 90 min, respectively. (3) The linear relationships between the concentrations of D- and L-alanine and the output of the sensor were obtained at 3.56-106.8 microg of D-alanine and 5.34-71.3 microg of L-alanine. (4) The concentrations of D- and L-alanine in Meretrix iusoria, Patinopecten yessonsi, and Corbicula leana obtained by the proposed assay were in good agreement with those determined by a conventional method.

  4. Inducible L-alanine exporter encoded by the novel gene ygaW (alaE) in Escherichia coli.

    PubMed

    Hori, Hatsuhiro; Yoneyama, Hiroshi; Tobe, Ryuta; Ando, Tasuke; Isogai, Emiko; Katsumata, Ryoichi

    2011-06-01

    We previously isolated a mutant hypersensitive to L-alanyl-L-alanine from a non-L-alanine-metabolizing Escherichia coli strain and found that it lacked an inducible l-alanine export system. Consequently, this mutant showed a significant accumulation of intracellular L-alanine and a reduction in the L-alanine export rate compared to the parent strain. When the mutant was used as a host to clone a gene(s) that complements the dipeptide-hypersensitive phenotype, two uncharacterized genes, ygaW and ytfF, and two characterized genes, yddG and yeaS, were identified. Overexpression of each gene in the mutant resulted in a decrease in the intracellular l-alanine level and enhancement of the L-alanine export rate in the presence of the dipeptide, suggesting that their products function as exporters of L-alanine. Since ygaW exhibited the most striking impact on both the intra- and the extracellular L-alanine levels among the four genes identified, we disrupted the ygaW gene in the non-L-alanine-metabolizing strain. The resulting isogenic mutant showed the same intra- and extracellular L-alanine levels as observed in the dipeptide-hypersensitive mutant obtained by chemical mutagenesis. When each gene was overexpressed in the wild-type strain, which does not intrinsically excrete alanine, only the ygaW gene conferred on the cells the ability to excrete alanine. In addition, expression of the ygaW gene was induced in the presence of the dipeptide. On the basis of these results, we concluded that YgaW is likely to be the physiologically most relevant exporter for L-alanine in E. coli and proposed that the gene be redesignated alaE for alanine export.

  5. Inducible l-Alanine Exporter Encoded by the Novel Gene ygaW (alaE) in Escherichia coli ▿

    PubMed Central

    Hori, Hatsuhiro; Yoneyama, Hiroshi; Tobe, Ryuta; Ando, Tasuke; Isogai, Emiko; Katsumata, Ryoichi

    2011-01-01

    We previously isolated a mutant hypersensitive to l-alanyl-l-alanine from a non-l-alanine-metabolizing Escherichia coli strain and found that it lacked an inducible l-alanine export system. Consequently, this mutant showed a significant accumulation of intracellular l-alanine and a reduction in the l-alanine export rate compared to the parent strain. When the mutant was used as a host to clone a gene(s) that complements the dipeptide-hypersensitive phenotype, two uncharacterized genes, ygaW and ytfF, and two characterized genes, yddG and yeaS, were identified. Overexpression of each gene in the mutant resulted in a decrease in the intracellular l-alanine level and enhancement of the l-alanine export rate in the presence of the dipeptide, suggesting that their products function as exporters of l-alanine. Since ygaW exhibited the most striking impact on both the intra- and the extracellular l-alanine levels among the four genes identified, we disrupted the ygaW gene in the non-l-alanine-metabolizing strain. The resulting isogenic mutant showed the same intra- and extracellular l-alanine levels as observed in the dipeptide-hypersensitive mutant obtained by chemical mutagenesis. When each gene was overexpressed in the wild-type strain, which does not intrinsically excrete alanine, only the ygaW gene conferred on the cells the ability to excrete alanine. In addition, expression of the ygaW gene was induced in the presence of the dipeptide. On the basis of these results, we concluded that YgaW is likely to be the physiologically most relevant exporter for l-alanine in E. coli and proposed that the gene be redesignated alaE for alanine export. PMID:21531828

  6. Investigation on physical properties of L-alanine: An effect of Methylene blue dye

    NASA Astrophysics Data System (ADS)

    Shkir, Mohd.; Yahia, I. S.; Al-Qahtani, A. M. A.; Ganesh, V.; AlFaify, S.

    2017-03-01

    In the present investigation, a bulk size (35 mm × 25 mm × 15 mm) single crystal of 0.1 wt% Methylene blue dye (MLB) added L-alanine is grown at room temperature using solution technique for the first time. The L-alanine crystals with higher concentrations of dye (0.5 and 1 wt%) were also grown. Solubility study was performed at different temperatures. Structural, vibrational and good quality was inveterate by powder XRD, FT-Raman and SEM analyses. High transmittance in dyed crystals was confirmed. The presence of MLB dye was confirmed by an absorption band centered at 650 nm. Optical band gap was calculated for pure and dyed L-alanine crystals and found to be 5.45 and 4.49 eV respectively. Photoluminescence intensity of UV-A emission band centered at 332 nm was found to be enhanced due to the presence of dye. The dielectric measurement was done in the wide frequency range. Furthermore, the third order nonlinear optical parameters are enhanced in dyed L-alanine crystals determined by Z-scan technique.

  7. Growth and characterization of pure and semiorganic nonlinear optical Lithium Sulphate admixtured l-alanine crystal

    NASA Astrophysics Data System (ADS)

    Vela, T.; Selvarajan, P.; Freeda, T. H.; Balasubramanian, K.

    2013-04-01

    Lithium sulphate admixtured l-alanine (LSLA) salt was synthesized and the solubility of the commercially available l-alanine and the synthesized LSLA sample was determined in de-ionized water at various temperatures. In accordance with the solubility data, the saturated aqueous solutions of l-alanine and lithium admixtured l-alanine were prepared separately and the single crystals of the samples were grown by the solution method with a slow evaporation technique. Studying single x-ray diffraction shows that pure and LSLA crystal belong to the orthorhombic system with a non-centrosymmetric space group P212121. Using the powder x-ray diffraction study, the crystallinity of the grown crystals is confirmed and the diffraction peaks are indexed. The various functional groups present in the pure and LSLA crystal are elucidated from Fourier transform infrared spectroscopy study. UV-visible transmittance is recorded to study the optical transmittance range for the grown crystals. The powder second harmonic generation test confirms the nonlinear optical property of the grown crystals. From the microhardness test, the hardness of the grown crystals is estimated. The dielectric behaviour, such as the dielectric constant and the loss of the sample, are measured as a function of temperature and frequency. The ac conductivity of the grown crystals is also studied and the activation energy is calculated.

  8. Surface interaction of L-alanine on hematite: an astrobiological implication.

    PubMed

    Pandey, Pramod; Pant, Chandra Kala; Gururani, Kavita; Arora, Priyanka; Kumar, Sumit; Sharma, Yogesh; Pathak, Hari Datt; Mehata, Mohan Singh

    2013-10-01

    In the present work, surface interaction of L-alanine (L-ala) has been investigated on hematite (α-Fe2O3), an abundant mineral on Mars, as a function of time (5 min-48 h), pH (4.0 and 6.20 ± 0.10) and concentration (1 × 10(-3) M-10 × 10(-3) M) with optical absorbance and energy-dispersive spectroscopy (EDS). Adsorption parameters (XM and KL) were calculated from Langmuir adsorption isotherms. L-alanine has maximum affinity (65.31 %) in its zwitterionic form at pH 6.20, while it is only 29.86 % adsorbed at pH 4.0. Possible astrobiological implications are discussed.

  9. Adsorption of di-l-alanine on Cu(110) investigated with scanning tunneling microscopy [rapid communication

    NASA Astrophysics Data System (ADS)

    Stensgaard, I.

    2003-11-01

    Sub-monolayer growth of a small chiral peptide, di- L-alanine, on Cu(1 1 0) was investigated by variable temperature scanning tunneling microscopy (STM). At low coverage and for temperatures above ≈-220 K the molecules nucleate along the [ 3¯ 3 2] direction to form short, mainly one-dimensional islands. An increase in coverage leads to the formation of [ 3¯ 3 2]-directed, elongated islands. Images with sub-molecular resolution reveal that the orientation of the molecules within one particular island depends on the deposition temperature. At higher coverage, up to one monolayer, the islands coalesce, giving rise to phase boundaries between domains of opposite orientation. An atomic-scale model for di- L-alanine on Cu(1 1 0) is presented.

  10. Structure and vibrational spectra of L-alanine L-alaninium picrate monohydrate

    NASA Astrophysics Data System (ADS)

    Ghazaryan, V. V.; Fleck, M.; Petrosyan, A. M.

    2012-05-01

    Preparation, crystal and molecular structure as well as vibrational spectra of the crystal L-alanine L-alaninium picrate monohydrate are described. The title crystal is monoclinic, space group P21. The asymmetric unit contains one dimeric (L-Ala⋯L-Ala+) cation, one picrate anion and a water molecule. The O⋯O distance in the dimeric cation is equal to 2.553(2) Å. The IR and Raman spectra are interpreted based on the structure.

  11. Characterisation of L-alanine and glycine absorption across the gut of an ancient vertebrate.

    PubMed

    Glover, Chris N; Bucking, Carol; Wood, Chris M

    2011-08-01

    This study utilised an in vitro technique to characterise absorption of two amino acids across the intestinal epithelium of Pacific hagfish, Eptatretus stoutii. Uptake of L-alanine and glycine conformed to Michaelis-Menten kinetics. An uptake affinity (K(m); substrate concentration required to attain a 50% uptake saturation) of 7.0 mM and an uptake capacity (J (max)) of 83 nmol cm(-2) h(-1) were described for L-alanine. The K(m) and J(max) for glycine were 2.2 mM and 11.9 nmol cm(-2) h(-1), respectively. Evidence suggested that the pathways of L-alanine and glycine absorption were shared, and sodium dependent. Further analysis indicated that glycine uptake was independent of luminal pH and proline, but a component of uptake was significantly impaired by 100-fold excesses of threonine or asparagine. The presence of a short-term (24 h) exposure to waterborne glycine, similar in nature to that which may be expected to occur when feeding inside an animal carcass, had no significant impact on gastrointestinal glycine uptake. This may indicate a lack of cross talk between absorptive epithelia. These results are the first published data to describe gastrointestinal uptake of an organic nutrient in the oldest extant vertebrate and may provide potential insight into the evolution of nutrient transport systems.

  12. Qualitative analysis of collective mode frequency shifts in L-alanine using terahertz spectroscopy.

    PubMed

    Taulbee, Anita R; Heuser, Justin A; Spendel, Wolfgang U; Pacey, Gilbert E

    2009-04-01

    We have observed collective mode frequency shifts in deuterium-substituted L-alanine, three of which have previously only been calculated. Terahertz (THz) absorbance spectra were acquired at room temperature in the spectral range of 66-90 cm(-1), or 2.0-2.7 THz, for L-alanine (L-Ala) and four L-Ala compounds in which hydrogen atoms (atomic mass = 1 amu) were substituted with deuterium atoms (atomic mass = 2 amu): L-Ala-2-d, L-Ala-3,3,3-d(3), L-Ala-2,3,3,3-d(4), and L-Ala-d(7). The absorbance maxima of two L-Ala collective modes in this spectral range were recorded for multiple spectral measurements of each compound, and the magnitude of each collective mode frequency shift due to increased mass of these specific atoms was evaluated for statistical significance. Calculations were performed which predict the THz absorbance frequencies based on the estimated reduced mass of the modes. The shifts in absorbance maxima were correlated with the location(s) of the substituted deuterium atom(s) in the L-alanine molecule, and the atoms contributing to the absorbing delocalized mode in the crystal structure were deduced using statistics described herein. The statistical analyses presented also indicate that the precision of the method allows reproducible frequency shifts as small as 1 cm(-1) or 0.03 THz to be observed and that these shifts are not random error in the measurement.

  13. L-alanine uptake in membrane vesicles from Mytilus edulis gills

    SciTech Connect

    Pajor, A.M.; Wright, S.H.

    1986-03-05

    Previous studies have shown that gills from M. edulis can accumulate L-alanine from seawater by a saturable process specific for ..cap alpha..-neutral amino acids. This uptake occurs against chemical gradients in excess of 10/sup 6/ to 1. To further characterize this uptake, membrane vesicles were prepared from M. edulis gill tissue by differential centrifugation. Enrichments of putative enzyme markers (relative to that in combined initial fractions) were as follows: ..gamma..-Glutamyltranspeptidase, 25-30x; Alkaline Phosphatase, 5-6x; K/sup +/-dependent para-Nitrophenyl Phosphatase, 3-5x; Succinate Dehydrogenase 0.1-0.2x. These results suggest that the preparation is enriched in plasma membranes, although histochemical studies will be needed to verify this. The time course of /sup 14/C-L-alanine uptake in the presence of inwardly-directed Na/sup +/ gradient showed a transient overshoot (3-5 fold) at 10 minutes which decreased to equilibrium after six hours. The size of the overshoot and early uptake rates depended on the size of the inwardly-directed Na/sup +/ gradient. No overshoot was seen in the presence of inwardly-directed gradients of LiCl or choline-Cl, or with equilibrium concentrations NaCl or mannitol. A reduced overshoot was seen with a gradient of NaSCN. A small overshoot was seen with an inwardly-directed gradient of KCl. Transport of L-alanine included saturable and diffusive components. Uptake of 6 ..mu..M L-alanine was inhibited more than 80% by 100 ..mu..M ..cap alpha..-zwitterionic amino acids (alanine, leucine, glycine); by 30 to 75% by proline, aspartate and lysine; and less than 20% by a ..beta..-amino acid, taurine. The results of these experiments agree with those from intact gill studies and support the hypothesis that L-alanine is transported into gill epithelial cells by a secondary active transport process involving Na/sup +/.

  14. Evidence for disorder in L-alanine lattice detected by Pulsed-EPR spectroscopy at cryogenic temperatures.

    PubMed

    Maltar-Strmecki, N; Rakvin, B

    2006-03-13

    The unusual behavior of lattice dynamics of L-alanine has been assigned to intermolecular dynamics and localization of vibrational energy. Recent heat capacity and Pulsed-EPR measurements support presence of thermally activated dynamic orientational disorder in the L-alanine lattice below 20 K. In the present study, the additional evidence for possible thermally activated disordered behavior of L-alanine lattice have been obtained by investigating dependences of longitudinal relaxation time of first stable L-alanine radical, SAR1, on sample cooling rates for the same low temperature interval. The obtained relaxation time by Pulsed-EPR shows clear dependence on cooling rates and this behavior can be explained within two types of suggested spin-lattice relaxation mechanisms for the paramagnetic centers in the hydrogen-bonded organic crystal.

  15. Unequal hydrolysis of salicylic acid-D-alanine and salicylic acid-L-alanine conjugate in rabbit intestinal microorganisms.

    PubMed

    Nakamura, J; Tagami, C; Nishida, K; Sasaki, H

    1992-02-01

    The behavior of salicylic acid-D-alanine conjugate (salicyl-D-alanine) following intravenous, oral and intracecal administration was examined in rabbits, then compared with that of salicylic acid-L-alanine conjugate (salicyl-L-alanine) as reported previously. Following intravenous administration, salicyl-D-alanine eliminated rapidly from the blood, and its blood concentration was almost identical with that of salicyl-L-alanine. In both cases, salicylic acid could not be detected in the blood, indicating that systemic de-conjugation of D-alanine might not occur. Unchanged salicyl-D-alanine was found in the blood mainly following oral and intracecal administration of salicyl-D-alanine. On the other hand, salicylic acid formed extensively following oral and intracecal administration of salicyl-L-alanine, suggesting that the presystemic de-conjugation of D-alanine and L-alanine was unequal. Furthermore, in vitro incubation of salicyl-D-alanine with cecal content, in which the major source of salicyl-L-alanine hydrolysis is found, showed that the hydrolysis of salicyl-D-alanine was negligible in rabbit intestinal microorganisms.

  16. Low-temperature Fourier transform infrared spectra and hydrogen bonding in polycrystalline L-alanine.

    PubMed

    Rozenberg, M; Shoham, G; Reva, I; Fausto, R

    2003-12-01

    The 400-4000 cm(-1) FTIR spectra of pure NH and isotopically substituted (10 and 90% doped ND/NH) polycrystalline L-alanine were recorded in the temperature range 10-300 K. The observed temperature dependence and isotopic shifts behavior enabled to identify, in the spectra of the doped crystals, three well-separated bands ascribable to either the NH or ND stretching vibrations associated with the three different types of hydrogen bonds existing in the crystal. The observed red shifts of these bands relative to the frequency of a reference "free" NH (or ND) stretching mode were found to correlate well with the H-bond distances found in the crystal and provide an indirect way of estimating the enthalpies associated with each type of H-bond found in the crystal. In the low-frequency deformation and torsional spectral region (below 2000 cm(-1)), several bands, which were found to be affected by isotopic substitution, were identified as belonging to the NH3(+) group. Several bands show splitting at low temperatures, indicating the occurrence of a significant reorganization in the crystal structure, which with all probability results mainly from changes in the proton positions. Finally, the literature assignments of the IR spectra of both crystalline NH3(+) and ND3(+) L-alanine were revised taking into consideration their temperature dependence and behavior upon deuteration.

  17. Rapid Crystallization of L-Alanine on Engineered Surfaces using Metal-Assisted and Microwave-Accelerated Evaporative Crystallization

    PubMed Central

    Alabanza, Anginelle M.; Pozharski, Edwin; Aslan, Kadir

    2011-01-01

    This study demonstrates the application of metal-assisted and microwave-accelerated evaporative crystallization (MA-MAEC) technique to rapid crystallization of L-alanine on surface engineered silver nanostructures. In this regard, silver island films (SIFs) were modified with hexamethylenediamine (HMA), 1-undecanethiol (UDET), and 11-mercaptoundecanoic acid (MUDA), which introduced -NH2, -CH3 and -COOH functional groups to SIFs, respectively. L-Alanine was crystallized on these engineered surfaces and blank SIFs at room temperature and using MA-MAEC technique. Significant improvements in crystal size, shape, and quality were observed on HMA-, MUDA- and UDET-modified SIFs at room temperature (crystallization time = 144, 40 and 147 min, respectively) as compared to those crystals grown on blank SIFs. Using the MA-MAEC technique, the crystallization time of L-alanine on engineered surfaces were reduced to 17 sec for microwave power level 10 (i.e., duty cycle 100%) and 7 min for microwave power level 1 (duty cycle 10%). Raman spectroscopy and powder x-ray diffraction (XRD) measurements showed that L-Alanine crystals grown on engineered surfaces using MA-MAEC technique had identical characteristic peaks of L-alanine crystals grown using traditional evaporative crystallization. PMID:22267957

  18. Gliotoxicity of the cyanotoxin, β-methyl-amino-L-alanine (BMAA).

    PubMed

    Chiu, Alexander S; Gehringer, Michelle M; Braidy, Nady; Guillemin, Gilles J; Welch, Jeffrey H; Neilan, Brett A

    2013-01-01

    The amino acid variant β-methyl-amino-L-alanine (BMAA) has long been associated with the increased incidence and progression of the amyotrophic lateral sclerosis/Parkinsonism dementia complex (ALS/PDC). Previous studies have indicated that BMAA damages neurons via excitotoxic mechanisms. We have challenged rat olfactory ensheathing cells (OECs) with exogenous BMAA and found it to be cytotoxic. BMAA also induces a significant increase in Ca2+ influx, enhanced production of reactive oxygen species (ROS), and disrupts mitochondrial activity in OECs. This is the first study investigating BMAA toxicity using pure glial cells. These findings align BMAA with the three proposed mechanisms of degeneration in ALS, those being non-cell autonomous death, excitotoxicity and mitochondrial dysfunction.

  19. Distinguishing the cyanobacterial neurotoxin β-N-methylamino-L-alanine (BMAA) from other diamino acids.

    PubMed

    Banack, S A; Metcalf, J S; Spáčil, Z; Downing, T G; Downing, S; Long, A; Nunn, P B; Cox, P A

    2011-04-01

    β-N-methylamino-L-alanine (BMAA) is produced by diverse taxa of cyanobacteria, and has been detected by many investigators who have searched for it in cyanobacterial blooms, cultures and collections. Although BMAA is distinguishable from proteinogenic amino acids and its isomer 2,4-DAB using standard chromatographic and mass spectroscopy techniques routinely used for the analysis of amino acids, we studied whether BMAA could be reliably distinguished from other diamino acids, particularly 2,6-diaminopimelic acid which has been isolated from the cell walls of many bacterial species. We used HPLC-FD, UHPLC-UV, UHPLC-MS, and triple quadrupole tandem mass spectrometry (UHPLC-MS/MS) to differentiate BMAA from the diamino acids 2,6-diaminopimelic acid, N-2(amino)ethylglycine, lysine, ornithine, 2,4-diaminosuccinic acid, homocystine, cystine, tryptophan, as well as other amino acids including asparagine, glutamine, and methionine methylsulfonium.

  20. Catalytic Stereoinversion of L-Alanine to Deuterated D-Alanine.

    PubMed

    Moozeh, Kimia; So, Soon Mog; Chin, Jik

    2015-08-03

    A combination of an achiral pyridoxal analogue and a chiral base has been developed for catalytic deuteration of L-alanine with inversion of stereochemistry to give deuterated D-alanine under mild conditions (neutral pD and 25 °C) without the use of any protecting groups. This system can also be used for catalytic deuteration of D-alanine with retention of stereochemistry to give deuterated D-alanine. Thus a racemic mixture of alanine can be catalytically deuterated to give an enantiomeric excess of deuterated D-alanine. While catalytic deracemization of alanine is forbidden by the second law of thermodynamics, this system can be used for catalytic deracemization of alanine with deuteration. Such green and biomimetic approach to catalytic stereocontrol provides insights into efficient amino acid transformations.

  1. Spectrofluorimetric determination of ofloxacin in milk with N-(9-fluorenylmethyloxycarbonyl)-L-alanine.

    PubMed

    Tong, Zhao; Bianfei, Yu; Wanjin, Tang; Haixia, Zhang

    2015-09-05

    It was found that N-(9-fluorenylmethyloxycarbonyl)-L-alanine (F-Ala) could interact with ofloxacin (OFL) and enhance the fluorescence of OFL, which could be used to set up a new fluorescence spectrophotometry method to detect OFL without isolation procedure. The experimental conditions were discussed and when MeOH was used as solvent, 0.001 μg mL(-1) of OFL could be detected. For making the method could be used easily in milk samples, MeOH/H2O (v/v, 4:1, pH 4.1) was used as the optimal solvent condition, the limit of quantification of OFL could be reached 0.01 μg mL(-1) in milk samples with recovery more than 88% at least.

  2. Thiophenyl-substituted triazolyl-thione L-alanine: asymmetric synthesis, aggregation and biological properties.

    PubMed

    Saghyan, Ashot S; Simonyan, Hayarpi M; Petrosyan, Satenik G; Geolchanyan, Arpine V; Roviello, Giovanni N; Musumeci, Domenica; Roviello, Valentina

    2014-10-01

    In this work, we report the asymmetric synthesis and characterization of an artificial amino acid based on triazolyl-thione L-alanine, which was modified with a thiophenyl-substituted moiety, as well as in vitro studies of its nucleic acid-binding ability. We found, by dynamic light scattering studies, that the synthetic amino acid was able to form supramolecular aggregates having a hydrodynamic diameter higher than 200 nm. Furthermore, we demonstrated, by UV and CD experiments, that the heteroaromatic amino acid, whose enzymatic stability was demonstrated by HPLC analysis also after 24 h of incubation in human serum, was able to bind a RNA complex, which is a feature of biomedical interest in view of innovative antiviral strategies based on modulation of RNA-RNA molecular recognition.

  3. Controlled radical polymerization of an acrylamide containing L-alanine moiety via ATRP.

    PubMed

    Rafiee, Zahra

    2016-02-01

    Homopolymerization of an optically active acrylamide having an amino acid moiety in the side chain, N-acryloyl-L-alanine (AAla) was carried out via atom transfer radical polymerization (ATRP) at room temperature using 2-hydroxyethyl-2'-methyl-2'-bromopropionate (HMB) or sodium-4-(bromomethyl)benzoate (SBB) as initiator in pure water, methanol/water mixture and pure methanol solvents. The polymerization reaction resulted in the optically active biocompatible amino acid-based homopolymer in good yield with narrow molecular weight distribution. The number average molecular weight increased with conversion and polydispersity was low. The structure and molecular weight of synthesized polymer were characterized by (1)H NMR, FT-IR spectroscopic techniques and size-exclusion chromatography.

  4. Discovery of an L-alanine ester prodrug of the Hsp90 inhibitor, MPC-3100.

    PubMed

    Kim, Se-Ho; Tangallapally, Rajendra; Kim, In Chul; Trovato, Richard; Parker, Daniel; Patton, J Scott; Reeves, Leslie; Bradford, Chad; Wettstein, Daniel; Baichwal, Vijay; Papac, Damon; Bajji, Ashok; Carlson, Robert; Yager, Kraig M

    2015-11-15

    Various types of Hsp90 inhibitors have been and continue to undergo clinical investigation. One development candidate is the purine-based, synthetic Hsp90 inhibitor 1 (MPC-3100), which successfully completed a phase I clinical study. However, further clinical development of 1 was hindered by poor solubility and consequent formulation issues and promoted development of a more water soluble prodrug. Towards this end, numerous pro-moieties were explored in vitro and in vivo. These studies resulted in identification of L-alanine ester mesylate, 2i (MPC-0767), which exhibited improved aqueous solubility, adequate chemical stability, and rapid bioconversion without the need for solubilizing excipients. Based on improved physical characteristics and favorable PK and PD profiles, 2i mesylate was selected for further development. A convergent, scalable, chromatography-free synthesis for 2i mesylate was developed to support further clinical evaluation.

  5. Growth, Structural And Optical Studies On Bis L-alanine Lithium Chloride (BLALC) Single Crystal

    NASA Astrophysics Data System (ADS)

    Rose, A. S. J. Lucia; Selvarajan, P.; Perumal, S.

    2011-10-01

    Bis L-alanine Lithium Chloride (BLALC) single crystals were grown successfully by solution method with slow evaporation technique at room temperature. Crystals of size 15 x 9 x 4 mm3 have been obtained in 28 days. The grown crystals were colourless and transparent. Single crystal X-ray diffraction (XRD) study showed that BLALC belongs to orthorhombic system with a non-centro-symmetric space group P212121. The crystallinity of BLALC crystal was confirmed by the powder X-ray diffraction study and diffraction peaks were indexed. The functional groups of the grown crystals have been identified by FTIR studies. UV-visible transmittance spectrum was recorded to study the optical transparency of BLALC crystal. The nonlinear optical (NLO) property of the grown crystal was confirmed by Kurtz-Perry powder technique.

  6. Experimental and DFT computational studies of L-alanine cadmium chloride crystals

    NASA Astrophysics Data System (ADS)

    Ignatius, I. Cicili; Dheivamalar, S.; Kirubavathi, K.; Selvaraju, K.

    2016-05-01

    In this work, we report the combined experimental and theoretical study on molecular structure and vibrational spectra of nonlinear optical crystal L-alanine cadmium chloride (LACC). The single X-ray diffraction studies have revealed that the compound crystallizes in monoclinic system C2 space group with cell parameters a = 16.270, b = 7.358, c = 7.887 and Z = 4. FTIR and Raman spectra of the nonlinear optical materials LACC have been recorded and analyzed. The optimized geometric bond length and bond angles are obtained with the help of density functional theory (DFT) (B3LYP) calculation. The optimized geometric bond lengths and bond angles obtained by using DFT show good agreement with the experimental data. Using the natural bond orbital analysis the electronic effect and hydrogen bonding were confirmed. The HOMO-LUMO energy gap and the first order hyperpolarizability were calculated and it supports the nonlinear optical activity of LACC crystal.

  7. Fibrous biodegradable l-alanine-based scaffolds for vascular tissue engineering.

    PubMed

    Srinath, Deepta; Lin, Shigang; Knight, Darryl K; Rizkalla, Amin S; Mequanint, Kibret

    2014-07-01

    In vascular tissue engineering, three-dimensional (3D) biodegradable scaffolds play an important role in guiding seeded cells to produce matrix components by providing both mechanical and biological cues. The objective of this work was to fabricate fibrous biodegradable scaffolds from novel poly(ester amide)s (PEAs) derived from l-alanine by electrospinning, and to study the degradation profiles and its suitability for vascular tissue-engineering applications. In view of this, l-alanine-derived PEAs (dissolved in chloroform) were electrospun together with 18-30% w/w polycaprolactone (PCL) to improve spinnability. A minimum of 18% was required to effectively electrospin the solution while the upper value was set in order to limit the influence of PCL on the electrospun PEA fibres. Electrospun fibre mats with average fibre diameters of ~0.4 µm were obtained. Both fibre diameter and porosity increased with increasing PEA content and solution concentration. The degradation of a PEA fibre mat over a period of 28 days indicated that mass loss kinetics was linear, and no change in molecular weight was found, suggesting a surface erosion mechanism. Human coronary artery smooth muscle cells (HCASMCs) cultured for 7 days on the fibre mats showed significantly higher viability (p < 0.0001), suggesting that PEA scaffolds provided a better microenvironment for seeded cells compared with control PCL fibre mats of similar fibre diameter and porosity. Furthermore, elastin expression on the PEA fibre mats was significantly higher than the pure PEA discs and pure PCL fibre mat controls (p < 0.0001). These novel biodegradable PEA fibrous scaffolds could be strong candidates for vascular tissue-engineering applications.

  8. Microwave-assisted synthesis and characterization of optically active poly (ester-imide)s incorporating L-alanine.

    PubMed

    Zahmatkesh, Saeed; Hajipour, Abdol R

    2010-04-01

    Pyromellitic dianhydride (1) was reacted with L-alanine (2) to result [N,N'-(pyromellitoyl)-bis-L-alanine diacid] (3). This compound (3) was converted to N,N'-(pyromellitoyl)-bis-L-alanine diacyl chloride (4) by reaction with thionyl chloride. The microwave-assisted polycondensation of this diacyl chloride (4) with polyethyleneglycol-diol (PEG-200) and/or three synthetic aromatic diols furnish a series of new PEIs and Co-PEIs in a laboratory microwave oven (Milestone). The resulting polymers and copolymers have inherent viscosities in the range of 0.31-0.53 dl g(-1). These polymers are optically active, thermally stable and soluble in polar aprotic solvents such as DMF, DMSO, NMP, DMAc, and sulfuric acid. All of the above polymers were fully characterized by IR spectroscopy, (1)H NMR spectroscopy, elemental analyses, specific rotation and thermal analyses. Some structural characterizations and physical properties of these optically active PEIs and Co-PEIs have been reported.

  9. Contribution of L-alanine dehydrogenase to in vivo persistence and protective efficacy of the BCG vaccine.

    PubMed

    Scandurra, Gabriella M; Ryan, Anthony A; Pinto, Rachel; Britton, Warwick J; Triccas, James A

    2006-01-01

    The tuberculosis (TB) vaccine strain Mycobacterium bovis BCG is unable to utilise alanine and this deficiency is thought to inhibit the growth of the vaccine in vivo and limit vaccine efficacy. In this report we demonstrate that L-alanine catabolism can be conferred on BCG by introduction of the gene encoding L-alanine dehydrogenase (Ald) of Mycobacterium tuberculosis. Restoration of Ald activity did not change the in vivo growth of BCG in macrophages or mice, and protection against aerosol M. tuberculosis infection was not altered by addition of ald to the BCG vaccine. These results demonstrate that the inability to utilise L-alanine is not a contributing factor to the attenuated phenotype of BCG and does not influence the protective efficacy of the vaccine against TB.

  10. High-temperature Raman study of L-alanine, L-threonine and taurine crystals related to thermal decomposition

    NASA Astrophysics Data System (ADS)

    Cavaignac, A. L. O.; Lima, R. J. C.; Façanha Filho, P. F.; Moreno, A. J. D.; Freire, P. T. C.

    2016-03-01

    In this work high-temperature Raman spectra are used to compare temperature dependence of the lattice mode wavenumber of L-alanine, L-threonine and taurine crystals. Anharmonic effects observed are associated with intermolecular N-H· · ·O hydrogen bond that plays an important role in thermal decomposition process of these materials. Short and strong hydrogen bonds in L-alanine crystal were associated with anharmonic effects in lattice modes leading to low thermal stability compared to taurine crystals. Connection between thermal decomposition process and anharmonic effects is furnished for the first time.

  11. Determination of β-Cyano-L-alanine, γ-Glutamyl-β-cyano-L-alanine, and Common Free Amino Acids in Vicia sativa (Fabaceae) Seeds by Reversed-Phase High-Performance Liquid Chromatography

    PubMed Central

    Megías, Cristina; Cortés-Giraldo, Isabel; Girón-Calle, Julio; Vioque, Javier; Alaiz, Manuel

    2014-01-01

    A method for determination of β-cyano-L-alanine, γ-glutamyl-β-cyano-L-alanine and other free amino acids in Vicia sativa is presented. Seed extracts were derivatized by reaction with diethyl ethoxymethylenemalonate and analyzed by reverse-phase high-performance liquid chromatography. Calibration curves showed very good linearity of the response. The limit of detection and quantification was 0.15 and 0.50 μM, respectively. The method has high intra- (RSD = 0.28–0.31%) and interrepeatability (RSD = 2.76–3.08%) and remarkable accuracy with a 99% recovery in spiked samples. The method is very easy to carry out and allows for ready analysis of large number of samples using very basic HPLC equipment because the derivatized samples are very stable and have very good chromatographic properties. The method has been applied to the determination of γ-glutamyl-β-cyano-L-alanine, β-cyano-L-alanine, and common free amino acids in eight wild populations of V. sativa from southwestern Spain. PMID:25587488

  12. β-(1-Azulenyl)-L-alanine--a functional probe for determination of pKa of histidine residues.

    PubMed

    Gosavi, Pallavi M; Moroz, Yurii S; Korendovych, Ivan V

    2015-03-28

    β-(1-Azulenyl)-L-alanine (AzAla) can be incorporated into the influenza A virus M2 proton channel. AzAla's sensitivity to the protonation state of the nearby histidines and the lack of environmental fluorescence dependence allow for direct and straightforward determination of histidine pKa values in ion channels.

  13. The GerW protein is essential for L-alanine-stimulated germination of Bacillus subtilis spores.

    PubMed

    Kuwana, Ritsuko; Takamatsu, Hiromu

    2013-11-01

    GerW (formerly called YtfJ) is a protein found in dormant spores of Bacillus subtilis. We have studied spore proteins in B. subtilis before, and here we report the characterization of GerW protein. Northern blot analysis revealed that gerW mRNA was transcribed by SigF-containing RNA polymerase beginning 1 h after the initiation of sporulation. Fluorescence was detected in forespores and dormant spores of B. subtilis recombinant strains expressing GerW-GFP. During germination in the presence of L-alanine or a mixture of L-asparagine, D-glucose, D-fructose and potassium ions (AGFK), normal spores of B. subtilis became darkened, stained positive with Hoechst 33342 and carboxyfluorescein diacetate succinimidyl ester (CFDA-SE), and released dipicolinic acid (DPA). In the case of gerW-deficient spores, AGFK triggered germination in a manner similar to that seen in the wild-type spores, whereas spores stimulated by L-alanine remained refractive under the phase contrast microscope, failed to stain positive with Hoechst 33342 or CFDA-SE, and released almost no DPA. These results indicate that GerW is essential for the L-alanine-induced breakdown of spore dormancy followed by core rehydration and the resumption of enzymatic activity, and suggest that GerW is involved in the early stages of germination in the presence of l-alanine.

  14. Computational analysis of binding affinity and neural response at the l-alanine receptor

    NASA Astrophysics Data System (ADS)

    Venanzi, Thomas J.; Bryant, Bruce P.; Venanzi, Carol A.

    1995-10-01

    A model of analogue-receptor binding is developed for the l-alanine receptor in the channel catfish using the AM1-SM2 and ab initio SCRF computational methods. Besides interactions involving the zwitterionic moiety of the amino acid analogue and complementary subsites on the receptor, the model suggests the presence of a hydrophobic pocket with dispersion interactions between the receptor and the residue on the amino acid analogue. Conformational analysis suggests not only a small compact active site on the receptor, but also that the analogues with the highest affinity occupy nearly identical regions of space. Although the binding interaction is dominated by the ionic terms, AM1-SM2 calculations indicate that free energy terms associated with cavity formation, solvent reorganization, and dispersion interactions can be correlated to activation and neural response. From a consideration of this model, molecular features of the analogues that are important for binding and neural response were deduced and other analogues or ligands were developed and tested.

  15. Quantification of neurotoxin BMAA (β-N-methylamino-L-alanine) in seafood from Swedish markets

    PubMed Central

    Jiang, Liying; Kiselova, Nadezda; Rosén, Johan; Ilag, Leopold L.

    2014-01-01

    The neurotoxin β-N-methylamino-L-alanine (BMAA) produced naturally by cyanobacteria, diatoms and dinoflagellates can be transferred and accumulated up the food chain, and may be a risk factor for neurodegenerative diseases. This study provides the first systematic screening of BMAA exposure of a large population through the consumption of seafood sold in metropolitan markets. BMAA was distinguished from known isomers by liquid chromatography tandem mass spectrometry after acidic hydrolysis and derivatization. Using deuterium-labeled internal standard, BMAA was quantified as 0.01–0.90 μg/g wet weight of tissues in blue mussel, oyster, shrimp, plaice, char and herring, but was undetectable (<0.01 μg/g) in other samples (salmon, cod, perch and crayfish). Provided that the content of BMAA detected is relevant for intake calculations, the data presented may be used for a first estimation of BMAA exposure through seafood from Swedish markets, and to refine the design of future toxicological experiments and assessments. PMID:25373604

  16. β-N-methylamino-L-alanine (BMAA) metabolism in the aquatic macrophyte Ceratophyllum demersum.

    PubMed

    Downing, Simoné; Esterhuizen-Londt, Maranda; Grant Downing, Timothy

    2015-10-01

    The cyanobacterial neurotoxin, β-N-methylamino-l-alanine (BMAA) bioaccumulates and biomagnifies within the environment. However, most reports on the environmental presence of BMAA focus on the presence of BMAA in animals rather than in plants. Various laboratory studies have reported that this neurotoxin, implicated in neurodegenerative disease, is rapidly taken up by various aquatic and terrestrial plants, including crop plants. In this study the metabolism of BMAA in the aquatic macrophyte, Ceratophyllum demersum, was investigated using stable isotopically labelled BMAA. Data show that the toxin is rapidly removed from the environment by the plant. However, during depuration cellular BMAA concentrations decrease considerably, without excretion of the toxin back into the environment and without catabolism of BMAA, evidenced by the absence of label transfer to other amino acids. This strongly suggests that BMAA is metabolised via covalent modification and sequestered inside the plant as a BMAA-derivative. This modification may be reversed in humans following consumption of BMAA-containing plant material. These data therefore impact on the assessment of the risk of human exposure to this neurotoxin.

  17. Beta-N-methylamino-L-alanine (BMAA) in novel South African cyanobacterial isolates.

    PubMed

    Esterhuizen, M; Downing, T G

    2008-10-01

    Beta-N-methylamino-L-alanine (BMAA) is a neurotoxic non-proteinogenic amino acid reportedly produced by the majority of cyanobacterial isolates. A novel method was developed for the detection of BMAA in biological samples. Cultures representing the taxonomic diversity and geographic distribution in Southern Africa were collected and made uni-algal by standard methods before analysis for the presence of both free and protein-associated BMAA. Protein-associated BMAA was released by acid hydrolysis in an inert atmosphere. Samples were analyzed by gas chromatography-mass spectrometry (GC-MS) with pre-derivatization of amino acids using Phenomonex EZ:faast of the tested cultures, 96% were positive for BMAA although several were below the limit for quantification. BMAA presence was not related to the geographic origin or taxonomy of isolates and no correlation between free and bound BMAA concentrations was observed within or between taxonomic groups. These data offer the first confirmation of the taxonomic and geographic ubiquity of BMAA in freshwater cyanobacteria.

  18. Biotransfer of β-N-methylamino-L-alanine (BMAA) in a eutrophicated freshwater lake.

    PubMed

    Lage, Sandra; Annadotter, Heléne; Rasmussen, Ulla; Rydberg, Sara

    2015-03-02

    β-N-Methylamino-L-alanine (BMAA), a neurotoxic non-protein amino acid, plays a significant role as an environmental risk factor in neurodegenerative diseases, such as amyotrophic lateral sclerosis. BMAA producers occur globally, colonizing almost all habitats and represent species from distinct phytoplanktonic groups, i.e., cyanobacteria, diatoms, and dinoflagellates. Bioaccumulation of BMAA in invertebrate and vertebrate organisms has also been registered around the globe. In the Baltic Sea, BMAA has been detected in several commercial fish species, raising the question of the bioaccumulation of BMAA in Swedish limnic systems. Here we find the presence of BMAA in water samples from Lake Finjasjön and identify its bioaccumulation patterns in both plankti-benthivorous and piscivorous fish, according to fish species, total weight, gender, and season of collection. For the first time, a large number of fish individuals were used in order to draw conclusions on BMAA bioaccumulation in a closed ecological community based on a statistical approach. We may, therefore, conclude that feeding patterns (plankti-benthivorous) and increased age of fish may lead to a higher tissue concentration of BMAA.

  19. Biotransfer of β-N-Methylamino-l-alanine (BMAA) in a Eutrophicated Freshwater Lake

    PubMed Central

    Lage, Sandra; Annadotter, Heléne; Rasmussen, Ulla; Rydberg, Sara

    2015-01-01

    β-N-Methylamino-l-alanine (BMAA), a neurotoxic non-protein amino acid, plays a significant role as an environmental risk factor in neurodegenerative diseases, such as amyotrophic lateral sclerosis. BMAA producers occur globally, colonizing almost all habitats and represent species from distinct phytoplanktonic groups, i.e., cyanobacteria, diatoms, and dinoflagellates. Bioaccumulation of BMAA in invertebrate and vertebrate organisms has also been registered around the globe. In the Baltic Sea, BMAA has been detected in several commercial fish species, raising the question of the bioaccumulation of BMAA in Swedish limnic systems. Here we find the presence of BMAA in water samples from Lake Finjasjön and identify its bioaccumulation patterns in both plankti-benthivorous and piscivorous fish, according to fish species, total weight, gender, and season of collection. For the first time, a large number of fish individuals were used in order to draw conclusions on BMAA bioaccumulation in a closed ecological community based on a statistical approach. We may, therefore, conclude that feeding patterns (plankti-benthivorous) and increased age of fish may lead to a higher tissue concentration of BMAA. PMID:25738330

  20. Cyanobacterial neurotoxin β-N-methylamino-L-alanine (BMAA) in shark fins.

    PubMed

    Mondo, Kiyo; Hammerschlag, Neil; Basile, Margaret; Pablo, John; Banack, Sandra A; Mash, Deborah C

    2012-02-01

    Sharks are among the most threatened groups of marine species. Populations are declining globally to support the growing demand for shark fin soup. Sharks are known to bioaccumulate toxins that may pose health risks to consumers of shark products. The feeding habits of sharks are varied, including fish, mammals, crustaceans and plankton. The cyanobacterial neurotoxin β-N-methylamino-L-alanine (BMAA) has been detected in species of free-living marine cyanobacteria and may bioaccumulate in the marine food web. In this study, we sampled fin clips from seven different species of sharks in South Florida to survey the occurrence of BMAA using HPLC-FD and Triple Quadrupole LC/MS/MS methods. BMAA was detected in the fins of all species examined with concentrations ranging from 144 to 1836 ng/mg wet weight. Since BMAA has been linked to neurodegenerative diseases, these results may have important relevance to human health. We suggest that consumption of shark fins may increase the risk for human exposure to the cyanobacterial neurotoxin BMAA.

  1. Quantification of neurotoxin BMAA (β-N-methylamino-L-alanine) in seafood from Swedish markets.

    PubMed

    Jiang, Liying; Kiselova, Nadezda; Rosén, Johan; Ilag, Leopold L

    2014-11-06

    The neurotoxin β-N-methylamino-L-alanine (BMAA) produced naturally by cyanobacteria, diatoms and dinoflagellates can be transferred and accumulated up the food chain, and may be a risk factor for neurodegenerative diseases. This study provides the first systematic screening of BMAA exposure of a large population through the consumption of seafood sold in metropolitan markets. BMAA was distinguished from known isomers by liquid chromatography tandem mass spectrometry after acidic hydrolysis and derivatization. Using deuterium-labeled internal standard, BMAA was quantified as 0.01-0.90 μg/g wet weight of tissues in blue mussel, oyster, shrimp, plaice, char and herring, but was undetectable (<0.01 μg/g) in other samples (salmon, cod, perch and crayfish). Provided that the content of BMAA detected is relevant for intake calculations, the data presented may be used for a first estimation of BMAA exposure through seafood from Swedish markets, and to refine the design of future toxicological experiments and assessments.

  2. Lack of behavioral and neuropathological effects of dietary beta-methylamino-L-alanine (BMAA) in mice.

    PubMed

    Cruz-Aguado, Reyniel; Winkler, Daniella; Shaw, Christopher A

    2006-06-01

    Beta-methylamino-L-alanine (BMAA) is an excitotoxin allegedly involved in ALS-parkinsonism-dementia complex (ALS-PDC), a neurological disorder found in Guam and its surrounding islands, in which motor neuron disease symptoms can present alone or can co-occur with parkinsonism and dementia. Although in vitro experiments have shown BMAA's neurotoxic properties, studies using adult animals and systemic administration which better model the case of environmentally-induced human neurodegenerative diseases have not supported the involvement of BMAA in these disorders. In order to better test the hypothesized role of BMAA in neurodegeneration, we fed adult mice BMAA at a dose (28 mg/kg body weight, daily for 30 days) that reproduces the natural levels and tested the animals with a battery of behavioural tests, the latter including the evaluation of motor coordination, motor neuron-mediated reflexes, locomotion, muscular strength and memory. We also assessed whether BMAA exposure triggers cell death in the central nervous system (CNS) of mice by examining neuronal numbers and glial response in the spinal cord and the brain. No motor, cognitive or neuropathological outcome resulted from this feeding paradigm. Our findings support neither the causal role of BMAA in neurodegeneration nor the specific involvement of this amino acid in ALS-PDC.

  3. The non-protein amino acid β-N-methylamino-L-alanine in Portuguese cyanobacterial isolates.

    PubMed

    Cervantes Cianca, Rosa C; Baptista, Mafalda S; Lopes, Viviana R; Vasconcelos, Vitor M

    2012-06-01

    The tailor made amino acid β-N-methyl-amino-L-alanine (BMAA) is a neurotoxin produced by cyanobacteria. It has been associated with certain forms of progressive neurodegenerative disease, including sporadic Amyotrophic Lateral Sclerosis and Alzheimer's disease. Some different reports of BMAA in cyanobacterial blooms from lakes, reservoirs, and other water resources have been made by different investigators. We here report the detection of BMAA of both free and protein-bound produced by cyanobacteria, belonging to the Chroococcales, Oscillatoriales and Nostocales ordered. We use a rapid and sensitive HPLC-FD method that utilizes methanol elution and the Waters AQC Tag chemistry. On other hand, we have used three different assay procedures for BMAA extraction from cyanobacteria: Trichloroacetic acid (TCA), Methanol/Acetone and hydrochloric acid (HCl). All assays let successfully detect BMAA in all cyanobacteria samples analyzed. Nevertheless, with TCA and HCl extraction procedures the highest BMAA values, for free as well as protein-bound BMAA were detected. BMAA content could not be related to the taxonomy of the isolates or to their geographical origin, and no correlation between free and protein-bound BMAA concentrations were observed within or between taxonomic groups. These data offer confirmation of the taxonomic and geographic ubiquity of BMAA from naturally occurring populations of cyanobacteria, for the first time reported for estuaries.

  4. β-N-Methylamino-L-alanine Induces Neurological Deficits and Shortened Life Span in Drosophila

    PubMed Central

    Zhou, Xianchong; Escala, Wilfredo; Papapetropoulos, Spyridon; Zhai, R. Grace

    2010-01-01

    The neurotoxic non-protein amino acid, β-N-methylamino-L-alanine (BMAA), was first associated with the high incidence of Amyotrophic Lateral Sclerosis/Parkinsonism Dementia Complex (ALS/PDC) in Guam. Recently, BMAA has been implicated as a fierce environmental factor that contributes to the etiology of Alzheimer’s and Parkinson’s diseases, in addition to ALS. However, the toxicity of BMAA in vivo has not been clearly demonstrated. Here we report our investigation of the neurotoxicity of BMAA in Drosophila. We found that dietary intake of BMAA reduced life span, locomotor functions, and learning and memory abilities in flies. The severity of the alterations in phenotype is correlated with the concentration of BMAA detected in flies. Interestingly, developmental exposure to BMAA had limited impact on survival rate, but reduced fertility in females, and caused delayed neurological impairment in aged adults. Our studies indicate that BMAA exposure causes chronic neurotoxicity, and that Drosophila serves as a useful model in dissecting the pathogenesis of ALS/PDC. PMID:22069570

  5. The Cyanobacteria Derived Toxin Beta-N-Methylamino-L-Alanine and Amyotrophic Lateral Sclerosis

    PubMed Central

    Banack, Sandra Anne; Caller, Tracie A.; Stommel, Elijah W.

    2010-01-01

    There is mounting evidence to suggest that environmental factors play a major role in the development of neurodegenerative diseases like ALS (Amyotrophic Lateral Sclerosis). The non-protein amino acid beta-N-methylamino-L-alanine (BMAA) was first associated with the high incidence of Amyotrophic Lateral Sclerosis/Parkinsonism Dementia Complex (ALS/PDC) in Guam, and has been implicated as a potential environmental factor in ALS, Alzheimer’s disease, and other neurodegenerative diseases. BMAA has a number of toxic effects on motor neurons including direct agonist action on NMDA and AMPA receptors, induction of oxidative stress, and depletion of glutathione. As a non-protein amino acid, there is also the strong possibility that BMAA could cause intraneuronal protein misfolding, the hallmark of neurodegeneration. While an animal model for BMAA-induced ALS is lacking, there is substantial evidence to support a link between this toxin and ALS. The ramifications of discovering an environmental trigger for ALS are enormous. In this article, we discuss the history, ecology, pharmacology and clinical ramifications of this ubiquitous, cyanobacteria-derived toxin. PMID:22069578

  6. Growth and characterization of L-alanine cadmium bromide a semiorganic nonlinear optical crystals

    NASA Astrophysics Data System (ADS)

    Ilayabarathi, P.; Chandrasekaran, J.

    2012-10-01

    A new semiorganic nonlinear optical crystal, L-alanine cadmium bromide (LACB) was grown from aqueous solution by slow solvent evaporation method at room temperature. As grown crystals were characterized for its spectral, thermal, linear and second order nonlinear optical properties. LACB crystallizes in orthorhombic system and unit cell parameters a = 5.771(2) Å, b = 6.014(4) Å, c = 12.298(2) Å, α = β = γ = 90° and volume = 426.8(3) Å3. The mode of vibrations of different molecular groups present in the crystal was identified by FTIR study. The grown crystals were found to be transparent in the entire visible region. The thermal strength and the decomposition of the grown crystals were studied using TG/DTA and DSC analysis. Dielectric measurement revealed that the crystals had very low dielectric constant at higher frequency in room temperature. The mechanical behavior was studied by Vicker's microhardness tester. The grown crystal has negative photoconductivity nature. The fluorescence spectrum of the crystal was recorded and its optical band gap is about 3.356 eV. The NLO property of crystal using modified Kurtz-Perry powder technique with Nd:YAG laser light of wavelength 1064 nm indicated that their second harmonic generation (SHG) efficiency was half that of pure KDP.

  7. Cyanobacterial Neurotoxin β-N-Methylamino-L-alanine (BMAA) in Shark Fins

    PubMed Central

    Mondo, Kiyo; Hammerschlag, Neil; Basile, Margaret; Pablo, John; Banack, Sandra A.; Mash, Deborah C.

    2012-01-01

    Sharks are among the most threatened groups of marine species. Populations are declining globally to support the growing demand for shark fin soup. Sharks are known to bioaccumulate toxins that may pose health risks to consumers of shark products. The feeding habits of sharks are varied, including fish, mammals, crustaceans and plankton. The cyanobacterial neurotoxin β-N-methylamino-L-alanine (BMAA) has been detected in species of free-living marine cyanobacteria and may bioaccumulate in the marine food web. In this study, we sampled fin clips from seven different species of sharks in South Florida to survey the occurrence of BMAA using HPLC-FD and Triple Quadrupole LC/MS/MS methods. BMAA was detected in the fins of all species examined with concentrations ranging from 144 to 1836 ng/mg wet weight. Since BMAA has been linked to neurodegenerative diseases, these results may have important relevance to human health. We suggest that consumption of shark fins may increase the risk for human exposure to the cyanobacterial neurotoxin BMAA. PMID:22412816

  8. Theoretical and experimental study of valence photoelectron spectrum of D,L-alanine amino acid.

    PubMed

    Farrokhpour, H; Fathi, F; De Brito, A Naves

    2012-07-05

    In this work, the He-I (21.218 eV) photoelectron spectrum of D,L-alanine in the gas phase is revisited experimentally and theoretically. To support the experiment, the high level ab initio calculations were used to calculate and assign the photoelectron spectra of the four most stable conformers of gaseous alanine, carefully. The symmetry adapted cluster/configuration interaction (SAC-CI) method based on single and double excitation operators (SD-R) and its more accurate version, termed general-R, was used to separately calculate the energies and intensities of the ionization bands of the L- and D-alanine conformers. The intensities of ionization bands were calculated based on the monopole approximation. Also, natural bonding orbital (NBO) calculations were employed for better spectral band assignment. The relative electronic energy, Gibbs free energy, and Boltzmann population ratio of the conformers were calculated at the experimental temperature (403 K) using several theoretical methods. The theoretical photoelectron spectrum of alanine was calculated by summing over the spectra of individual D and L conformers weighted by different population ratios. Finally, the population ratio of the four most stable conformers of alanine was estimated from the experimental photoelectron spectrum using theoretical calculations for the first time.

  9. Deuterium NMR study of methyl group dynamics in L-alanine

    NASA Astrophysics Data System (ADS)

    Beshah, Kebede; Olejniczak, Edward T.; Griffin, Robert G.

    1987-05-01

    Deuterium quadrupole echo spectroscopy is used to study the dynamics of the CD3 group in polycrystalline L-alanine-d3. Temperature-dependent quadrupole echo line shapes, their spectral intensities and τ dependence, and the anisotropy of the 2H spin-lattice relaxation were employed to determine the rate and mechanism of the -CD3 group motion. The rigid lattice Pake pattern observed at low temperature (T<-120 °C) transforms to a triplet spectrum characteristic of threefold jumps in the intermediate exchange regime (-120 to -70 °C) and this in turn to a Pake pattern of reduced breadth at higher temperatures (T>-70 °C). The quadrupole echo line shapes and their τ dependence, which are especially sensitive to the rate and mechanism of the motion, can be simulated quantitatively with the threefold jump model. We find Ea=20.0 kJ/mol for this process which is higher than is observed for most methyl groups, probably because of steric crowding in the L-Ala molecule. Finally, we observe a line shape due to the presence of multiple crystallographic forms which suggests that this technique can be extended to studies of the dynamics of more complex systems.

  10. Quantification of neurotoxin BMAA (β-N-methylamino-L-alanine) in seafood from Swedish markets

    NASA Astrophysics Data System (ADS)

    Jiang, Liying; Kiselova, Nadezda; Rosén, Johan; Ilag, Leopold L.

    2014-11-01

    The neurotoxin β-N-methylamino-L-alanine (BMAA) produced naturally by cyanobacteria, diatoms and dinoflagellates can be transferred and accumulated up the food chain, and may be a risk factor for neurodegenerative diseases. This study provides the first systematic screening of BMAA exposure of a large population through the consumption of seafood sold in metropolitan markets. BMAA was distinguished from known isomers by liquid chromatography tandem mass spectrometry after acidic hydrolysis and derivatization. Using deuterium-labeled internal standard, BMAA was quantified as 0.01-0.90 μg/g wet weight of tissues in blue mussel, oyster, shrimp, plaice, char and herring, but was undetectable (<0.01 μg/g) in other samples (salmon, cod, perch and crayfish). Provided that the content of BMAA detected is relevant for intake calculations, the data presented may be used for a first estimation of BMAA exposure through seafood from Swedish markets, and to refine the design of future toxicological experiments and assessments.

  11. Cycas micronesica (Cycadales) plants devoid of endophytic cyanobacteria increase in beta-methylamino-L-alanine.

    PubMed

    Marler, Thomas E; Snyder, Laura R; Shaw, Christopher A

    2010-09-15

    Cycads are among the most ancient of extant Spermatophytes, and are known for their pharmacologically active compounds. beta-methylamino-l-alanine (BMAA) is one metabolite that been implicated as causal of human neurodegenerative diseases in Guam. We grew Cycas micronesica seedlings without endophytic cyanobacteria symbiosis, and quantified initial and ending BMAA in various plant tissues. BMAA increased 79% during nine months of seedling growth, and root tissue contained 75% of the ultimate BMAA pool. Endophytic cyanobacteria symbionts were not the source of BMAA increase in these seedlings, which contradicts previously reported claims that biosynthesis of this toxin by cyanobacteria initiates its accumulation in the Guam environment. The preferential loading of root tissue with BMAA does not support earlier reports that this toxin serves a defensive role against herbivory of leaf or seed tissues. The long history of conflicting results in Guam's cycad toxin research continues, and recent developments underscore the sense of urgency in continued research as this endangered cycad population approaches extirpation from the island.

  12. Laser trapping dynamics of L-alanine depending on the laser polarization

    NASA Astrophysics Data System (ADS)

    Yuyama, Ken-ichi; Ishiguro, Kei; Sugiyama, Teruki; Masuhara, Hiroshi

    2012-10-01

    We successfully demonstrate crystallization and crystal rotation of L-alanine in D2O solution using a focused laser beam of 1064 nm with right- or left-handed circularly polarization. Upon focusing each laser beam into a solution/air interface of the solution thin film, one single crystal is generally formed from the focal spot. The necessary time for the crystallization is systematically examined against polarization and power of the trapping laser. The significant difference in the average time is observed between two polarization directions at a relatively high laser power, where the left-handed circularly polarized laser takes 3 times longer than the right-handed one. On the other hand, the prepared crystal is stably trapped and rotated at the focal point by circularly polarized lasers after the crystallization, and the rotation direction is completely controlled by the polarization of the trapping laser. The mechanisms for the crystallization and the crystal rotation are discussed in terms of trapping force and rotation torque of circularly polarized lasers acting on the liquid-like clusters and its bulk crystal, respectively.

  13. Growth, structural, vibrational, optical, laser and dielectric aspects of L-alanine alaninium nitrate single crystal

    NASA Astrophysics Data System (ADS)

    Caroline, M. Lydia; Prakash, M.; Geetha, D.; Vasudevan, S.

    2011-09-01

    Bulk single crystals of L-alanine alaninium nitrate [abbreviated as LAAN], an intriguing material for frequency conversion has been grown from its aqueous solution by both slow solvent evaporation and by slow cooling techniques. The optimized pH value to grow good quality LAAN single crystal was found to be 2.5. The grown crystals were subjected to single crystal X-ray diffraction studies to determine the unit cell dimensions and morphology. Vibrational frequencies of the grown crystals by Fourier transform infrared spectroscopic technique were investigated. Also, the presence of hydrogen and carbon atoms in the grown sample was confirmed using proton and carbon NMR analyses. The dielectric constant and dielectric loss measurements of the as grown crystal at different temperatures and frequencies of the applied field are measured and reported. LAAN has good optical transmission in the entire visible region with cutoff wavelength within the UV region confirms its suitability for device fabrications. The existence of second harmonic generation signals was observed using Nd:YAG laser with fundamental wavelength of 1064 nm. Its Laser Damage Threshold (LDT) was measured and also tested by using a Q-switched Nd:YAG laser and the value of LDT of LAAN is 17.76 GW/cm 2 respectively, is found to be better than certain organic and semiorganic materials.

  14. Growth, structural, vibrational, optical, laser and dielectric aspects of L-alanine alaninium nitrate single crystal.

    PubMed

    Caroline, M Lydia; Prakash, M; Geetha, D; Vasudevan, S

    2011-09-01

    Bulk single crystals of l-alanine alaninium nitrate [abbreviated as LAAN], an intriguing material for frequency conversion has been grown from its aqueous solution by both slow solvent evaporation and by slow cooling techniques. The optimized pH value to grow good quality LAAN single crystal was found to be 2.5. The grown crystals were subjected to single crystal X-ray diffraction studies to determine the unit cell dimensions and morphology. Vibrational frequencies of the grown crystals by Fourier transform infrared spectroscopic technique were investigated. Also, the presence of hydrogen and carbon atoms in the grown sample was confirmed using proton and carbon NMR analyses. The dielectric constant and dielectric loss measurements of the as grown crystal at different temperatures and frequencies of the applied field are measured and reported. LAAN has good optical transmission in the entire visible region with cutoff wavelength within the UV region confirms its suitability for device fabrications. The existence of second harmonic generation signals was observed using Nd:YAG laser with fundamental wavelength of 1064 nm. Its Laser Damage Threshold (LDT) was measured and also tested by using a Q-switched Nd:YAG laser and the value of LDT of LAAN is 17.76GW/cm2 respectively, is found to be better than certain organic and semiorganic materials.

  15. Growth and characterization of L-alanine cadmium bromide a semiorganic nonlinear optical crystals.

    PubMed

    Ilayabarathi, P; Chandrasekaran, J

    2012-10-01

    A new semiorganic nonlinear optical crystal, l-alanine cadmium bromide (LACB) was grown from aqueous solution by slow solvent evaporation method at room temperature. As grown crystals were characterized for its spectral, thermal, linear and second order nonlinear optical properties. LACB crystallizes in orthorhombic system and unit cell parameters a=5.771(2)Å, b=6.014(4)Å, c=12.298(2)Å, α=β=γ=90° and volume=426.8(3)Å(3). The mode of vibrations of different molecular groups present in the crystal was identified by FTIR study. The grown crystals were found to be transparent in the entire visible region. The thermal strength and the decomposition of the grown crystals were studied using TG/DTA and DSC analysis. Dielectric measurement revealed that the crystals had very low dielectric constant at higher frequency in room temperature. The mechanical behavior was studied by Vicker's microhardness tester. The grown crystal has negative photoconductivity nature. The fluorescence spectrum of the crystal was recorded and its optical band gap is about 3.356 eV. The NLO property of crystal using modified Kurtz-Perry powder technique with Nd:YAG laser light of wavelength 1064nm indicated that their second harmonic generation (SHG) efficiency was half that of pure KDP.

  16. Optical, thermal and magnetic studies of pure and cobalt chloride doped L-alanine cadmium chloride

    NASA Astrophysics Data System (ADS)

    Benila, B. S.; Bright, K. C.; Delphine, S. Mary; Shabu, R.

    2017-03-01

    Single crystals of L-alanine cadmium chloride (LACC) and cobalt chloride (Co2+) doped LACC have been grown by the slow evaporation solution growth technique. The grown crystals were subjected to various characterizations such as powder XRD, SXRD, FTIR, UV-vis, EDAX, TG/DTA, VSM, Dielectric and Second Harmonic Generation (SHG) measurements. The lattice parameters of the grown crystals were determined by single crystal X-ray analysis. EDAX analysis confirms the presence of Co2+ ion in the host material. The functional group and optical behavior of the crystals were identified from FTIR and UV-vis spectrum analysis. Electrical parameters such as dielectric constant, dielectric loss have been studied. The thermal stability of the compound was found out using TGA/DTA analysis. Second Harmonic Generation of the samples was confirmed by Kurtz-Perry powder technique. Magnetic properties of the crystals studied by VSM were also reported. The encouraging results show that the cobalt chloride doped LACC crystals have greater potential applications in optical devices.

  17. L-Alanine augments rhizobacteria-induced systemic resistance in cucumber.

    PubMed

    Park, K S; Paul, D; Kim, J S; Park, J W

    2009-01-01

    Bacillus vallismortis strain EXTN-1 is a proven biotic elicitor of systemic resistance in many crops against various pathogens. L: -Alanine (Ala) was tested in cucumber as a chemical elicitor of induced systemic resistance (ISR) against Colletotrichum orbiculare. In the greenhouse, both Ala and EXTN-1 induced significant levels of disease suppression in cucumber against anthracnose. When cucumber plants were treated with EXTN-1 and Ala together, augmentative disease suppression was observed. Experiments with transgenic tobacco plants carrying pathogenesis-related genes fused with the beta-glucuronidase (GUS) reported gene (PR-1a::GUS & PDF 1.2::GUS) showed an enhanced activation of both PR-1a and PDF 1.2 genes upon combined treatment with Ala and EXTN-1. RT-PCR analysis with transgenic (PR-1a or PDF 1.2 over expressing) Arabidopsis plant showed more enhanced expression of resistance genes PR-1a and PDF 1.2 upon combined treatment with Ala and EXTN-1 than either alone. An augmentative ISR effect, when the bacterial elicitor and chemical elicitor were combined together, was confirmed.

  18. Overview of the potent cyanobacterial neurotoxin β-methylamino-L-alanine (BMAA) and its analytical determination.

    PubMed

    Porojan, Cristina; Mitrovic, Simon M; Yeo, Darren C J; Furey, Ambrose

    2016-10-01

    Blue-green algae are responsible for the production of different types of toxins which can be neurotoxic, hepatotoxic, cytotoxic and dermatotoxic and that can affect both aquatic and terrestrial life. Since its discovery the neurotoxin β-methylamino-L-alanine (BMAA) has been a cause for concern, being associated with the neurodegenerative disease amyotrophic lateral sclerosis/Parkinsonism-dementia complex (ALS/PDC). The initial focus was on Guam where it was observed that a high number of people were affected by the ALS/PDC complex. Subsequently, researchers were surprised to find levels of BMAA in post mortem brains from Canadian patients who also suffered from ALS/PDC. Recent research demonstrates that BMAA has been found at different levels in the aquatic food web in the brackish waters of the Baltic Sea. There is emerging evidence to suggest that sand-borne algae from Qatar can also contain BMAA. Furthermore, there is now concern because BMAA has been found not only in warmer regions of the world but also in temperate regions like Europe. The aim of this review is to focus on the methods of extraction and analysis of the neurotoxic non-protein amino acid BMAA. We also consider the neurotoxicity, aetiology, and diverse sources and routes of exposure to BMAA. In recent years, different methods have been developed for the analysis of BMAA. Some of these use HPLC-FD, UPLC-UV, UPLC-MS and LC-MS/MS using samples that have been derivatised or underivatised. To date the LC-MS/MS approach is the most widely used analytical technique as it is the most selective and sensitive method for BMAA determination.

  19. Environmental neurotoxins β-N-methylamino-l-alanine (BMAA) and mercury in shark cartilage dietary supplements.

    PubMed

    Mondo, Kiyo; Broc Glover, W; Murch, Susan J; Liu, Guangliang; Cai, Yong; Davis, David A; Mash, Deborah C

    2014-08-01

    Shark cartilage products are marketed as dietary supplements with claimed health benefits for animal and human use. Shark fin and cartilage products sold as extracts, dry powders and in capsules are marketed based on traditional Chinese medicine claims that it nourishes the blood, enhances appetite, and energizes multiple internal organs. Shark cartilage contains a mixture of chondroitin and glucosamine, a popular nutritional supplement ingested to improve cartilage function. Sharks are long-lived apex predators, that bioaccumulate environmental marine toxins and methylmercury from dietary exposures. We recently reported detection of the cyanobacterial toxin β-N-methylamino-l-alanine (BMAA) in the fins of seven different species of sharks from South Florida coastal waters. Since BMAA has been linked to degenerative brain diseases, the consumption of shark products may pose a human risk for BMAA exposures. In this report, we tested sixteen commercial shark cartilage supplements for BMAA by high performance liquid chromatography (HPLC-FD) with fluorescence detection and ultra performance liquid chromatography/mass spectrometry/mass spectrometry (UPLC-MS/MS). Total mercury (Hg) levels were measured in the same shark cartilage products by cold vapor atomic fluorescence spectrometry (CVAFS). We report here that BMAA was detected in fifteen out of sixteen products with concentrations ranging from 86 to 265μg/g (dry weight). All of the shark fin products contained low concentrations of Hg. While Hg contamination is a known risk, the results of the present study demonstrate that shark cartilage products also may contain the neurotoxin BMAA. Although the neurotoxic potential of dietary exposure to BMAA is currently unknown, the results demonstrate that shark cartilage products may contain two environmental neurotoxins that have synergistic toxicities.

  20. Acute β-N-Methylamino-L-alanine Toxicity in a Mouse Model

    PubMed Central

    Al-Sammak, Maitham Ahmed; Rogers, Douglas G.; Hoagland, Kyle D.

    2015-01-01

    The cyanobacterial neurotoxin β-N-methylamino-L-alanine (BMAA) is considered to be an “excitotoxin,” and its suggested mechanism of action is killing neurons. Long-term exposure to L-BMAA is believed to lead to neurodegenerative diseases including Parkinson's and Alzheimer's diseases and amyotrophic lateral sclerosis (Lou Gehrig's disease). Objectives of this study were to determine the presumptive median lethal dose (LD50), the Lowest-Observed-Adverse-Effect Level (LOAEL), and histopathologic lesions caused by the naturally occurring BMAA isomer, L-BMAA, in mice. Seventy NIH Swiss Outbred mice (35 male and 35 female) were used. Treatment group mice were injected intraperitoneally with 0.03, 0.3, 1, 2, and 3 mg/g body weight L-BMAA, respectively, and control mice were sham-injected. The presumptive LD50 of L-BMAA was 3 mg/g BW and the LOAEL was 2 mg/g BW. There were no histopathologic lesions in brain, liver, heart, kidney, lung, or spleen in any of the mice during the 14-day study. L-BMAA was detected in brains and livers in all of treated mice but not in control mice. Males injected with 0.03 mg/g BW, 0.3 mg/g BW, and 3.0 mg/g BW L-BMAA showed consistently higher concentrations (P < 0.01) in brain and liver samples as compared to females in those respective groups. PMID:26604922

  1. The temperature-dependent single-crystal Raman spectroscopy of a model dipeptide: L-Alanyl-L-alanine

    NASA Astrophysics Data System (ADS)

    Silva, J. G.; Arruda, L. M.; Pinheiro, G. S.; Lima, C. L.; Melo, F. E. A.; Ayala, A. P.; Filho, J. Mendes; Freire, P. T. C.

    2015-09-01

    A single-crystal of peptide L-alanyl-L-alanine (C6H12N2O3) was studied by Raman spectroscopy at low-temperature, and a tentative assignment of the normal modes was given. Evidence of a second order structural phase transition was found through Raman spectroscopy between the temperatures of 80 K and 60 K. Group theory considerations suggest that the transition leads the sample from the tetragonal to a monoclinic structure. Additionally, our study suggests that the mechanism for the structural phase transition is governed by the occupation of non-equivalent C1 local symmetry sites by the CH3 molecular groups. Analysis based on group theory suggests L-alanyl-L-alanine presents C2 symmetry at low temperatures.

  2. The temperature-dependent single-crystal Raman spectroscopy of a model dipeptide: L-Alanyl-L-alanine.

    PubMed

    Silva, J G; Arruda, L M; Pinheiro, G S; Lima, C L; Melo, F E A; Ayala, A P; Filho, J Mendes; Freire, P T C

    2015-09-05

    A single-crystal of peptide L-alanyl-L-alanine (C6H12N2O3) was studied by Raman spectroscopy at low-temperature, and a tentative assignment of the normal modes was given. Evidence of a second order structural phase transition was found through Raman spectroscopy between the temperatures of 80K and 60K. Group theory considerations suggest that the transition leads the sample from the tetragonal to a monoclinic structure. Additionally, our study suggests that the mechanism for the structural phase transition is governed by the occupation of non-equivalent C1 local symmetry sites by the CH3 molecular groups. Analysis based on group theory suggests L-alanyl-L-alanine presents C2 symmetry at low temperatures.

  3. Growth, spectral and crystallization perfection studies of semi organic non linear optical crystal - L-alanine lithium chloride

    NASA Astrophysics Data System (ADS)

    Redrothu, Hanumantharao; Kalainathan, S.; Bhagavannarayana, G.

    2012-06-01

    Single crystals of L-alanine lithium chloride single crystals were successfully grown using slow evaporation solution growth technique at constant temperature (303K). The formation of the new crystal has been confirmed by single-crystal X-ray diffraction, FT-IR studies. The crystalline perfection was analyzed by high-resolution X-ray diffraction (HRXRD) rocking curve measurements. The powder second harmonic generation (SHG) has been confirmed by Nd: YAG laser. The results have been discussed in detail.

  4. Inelastic neutron scattering, Raman, vibrational analysis with anharmonic corrections, and scaled quantum mechanical force field for polycrystalline L-alanine

    NASA Astrophysics Data System (ADS)

    Williams, Robert W.; Schlücker, Sebastian; Hudson, Bruce S.

    2008-01-01

    A scaled quantum mechanical harmonic force field (SQMFF) corrected for anharmonicity is obtained for the 23 K L-alanine crystal structure using van der Waals corrected periodic boundary condition density functional theory (DFT) calculations with the PBE functional. Scale factors are obtained with comparisons to inelastic neutron scattering (INS), Raman, and FT-IR spectra of polycrystalline L-alanine at 15-23 K. Calculated frequencies for all 153 normal modes differ from observed frequencies with a standard deviation of 6 wavenumbers. Non-bonded external k = 0 lattice modes are included, but assignments to these modes are presently ambiguous. The extension of SQMFF methodology to lattice modes is new, as are the procedures used here for providing corrections for anharmonicity and van der Waals interactions in DFT calculations on crystals. First principles Born-Oppenheimer molecular dynamics (BOMD) calculations are performed on the L-alanine crystal structure at a series of classical temperatures ranging from 23 K to 600 K. Corrections for zero-point energy (ZPE) are estimated by finding the classical temperature that reproduces the mean square displacements (MSDs) measured from the diffraction data at 23 K. External k = 0 lattice motions are weakly coupled to bonded internal modes.

  5. Crystal Engineering of l-Alanine with l-Leucine Additive using Metal-Assisted and Microwave-Accelerated Evaporative Crystallization.

    PubMed

    Mojibola, Adeolu; Dongmo-Momo, Gilles; Mohammed, Muzaffer; Aslan, Kadir

    2014-05-07

    In this work, we demonstrated that the change in the morphology of l-alanine crystals can be controlled with the addition of l-leucine using the metal-assisted and microwave accelerated evaporative crystallization (MA-MAEC) technique. Crystallization experiments, where an increasing stoichiometric amount of l-leucine is added to initial l-alanine solutions, were carried out on circular poly(methyl methacrylate) (PMMA) disks modified with a 21-well capacity silicon isolator and silver nanoparticle films using microwave heating (MA-MAEC) and at room temperature (control experiments). The use of the MA-MAEC technique afforded for the growth of l-alanine crystals with different morphologies up to ∼10-fold faster than those grown at room temperature. In addition, the length of l-alanine crystals was systematically increased from ∼380 to ∼2000 μm using the MA-MAEC technique. Optical microscope images revealed that the shape of l-alanine crystals was changed from tetragonal shape (without l-leucine additive) to more elongated and wire-like structures with the addition of the l-leucine additive. Further characterization of l-alanine crystals was undertaken by Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy and powder X-ray diffraction (PXRD) measurements. In order to elucidate the growth mechanism of l-alanine crystals, theoretical simulations of l-alanine's morphology with and without l-leucine additive were carried out using Materials Studio software in conjunction with our experimental data. Theoretical simulations revealed that the growth of l-alanine's {011} and {120} crystal faces were inhibited due to the incorporation of l-leucine into these crystal faces in selected positions.

  6. Determination of the non protein amino acid β-N-methylamino-l-alanine in estuarine cyanobacteria by capillary electrophoresis.

    PubMed

    Baptista, Mafalda S; Cianca, Rosa C C; Lopes, Viviana R; Almeida, C Marisa R; Vasconcelos, Vitor M

    2011-10-01

    A capillary electrophoretic method for the determination of the amino acid β-N-methylamino-l-alanine (BMAA) was achieved using a fused-silica capillary column (50 cm × 75 μm I.D.) filled with 5 mM sodium tetraborate solution (pH 9), with an applied voltage of 25 kV, at 25 °C. The method was then applied in quantifying BMAA in eighteen strains of lyophilized estuarine cyanobacteria, following amino acid extraction using 0.1 M trichloroacetic acid and 6 M hydrochloric acid, sequentially.

  7. Synthesis, growth and optical properties of an efficient nonlinear optical single crystal: L-alanine DL-malic acid

    NASA Astrophysics Data System (ADS)

    Kirubagaran, R.; Madhavan, J.

    2015-02-01

    Single crystals of L-alanine DL-malic acid (LADLMA) have been grown from aqueous solution by slow-cooling technique. Powder X-ray diffraction studies reveal the structure of the crystal to be orthorhombic. The nonlinear optical conversion efficiency test was carried out for the grown crystals using the Kurtz powder technique. The third order nonlinear refractive index and the nonlinear absorption coefficient where evaluated by Z-scan measurements. As the material have a negative refractive index it could be used in the protection of optical sensors such as night vision devices.

  8. Growth, spectroscopic, dielectric and nonlinear optical studies of semi organic nonlinear optical crystal - L-Alanine lithium chloride

    NASA Astrophysics Data System (ADS)

    Hanumantharao, Redrothu; Kalainathan, S.

    2012-02-01

    A new and efficient semi organic nonlinear optical crystal (NLO) from the amino acid family L-alanine lithium chloride (LAL) has been grown by slow evaporation technique from aqueous solution. The functional groups were identified from NMR spectral studies. Mass spectral analysis shows the molecular ion mass. Dielectric studies has been done for the grown crystal and relative SHG efficiency is measured by Kurtz and Perry method and found to about 0.43 times that of standard potassium dihydrogen phosphate (KDP) crystals. The compound crystallized in non-centrosymmetric space group Pna21. The results have been discussed in detail.

  9. Growth, spectroscopic, dielectric and nonlinear optical studies of semi organic nonlinear optical crystal--L-alanine lithium chloride.

    PubMed

    Hanumantharao, Redrothu; Kalainathan, S

    2012-02-01

    A new and efficient semi organic nonlinear optical crystal (NLO) from the amino acid family L-alanine lithium chloride (LAL) has been grown by slow evaporation technique from aqueous solution. The functional groups were identified from NMR spectral studies. Mass spectral analysis shows the molecular ion mass. Dielectric studies has been done for the grown crystal and relative SHG efficiency is measured by Kurtz and Perry method and found to about 0.43 times that of standard potassium dihydrogen phosphate (KDP) crystals. The compound crystallized in non-centrosymmetric space group Pna21. The results have been discussed in detail.

  10. Novel NMDA receptor-specific desensitization/inactivation produced by ingestion of the neurotoxins, β-N-methylamino-L-alanine (BMAA) or β-N-oxalylamino-L-alanine (BOAA/β-ODAP).

    PubMed

    Koenig, Jane H; Goto, Joy J; Ikeda, Kazuo

    2015-01-01

    The environmental neurotoxins BMAA (β-N-methylamino-L-alanine) and BOAA (β-N-oxalylamino-L-alanine) are implicated as possible causative agents for the neurodegenerative diseases, amyotrophic lateral sclerosis/ParkinsonismDementia complex (ALS/PDC) and neurolathyrism, respectively. Both are structural analogs of the neurotransmitter, glutamate, and bind postsynaptic glutamate receptors. In this study, the effect of ingestion of these toxins on the response of a singly-innervated, identified, glutamatergic postsynaptic cell in a living, undissected Drosophila is observed by intracellular recording. Previously we have reported that ingested BMAA behaves as an NMDA agonist that produces an abnormal NMDA response in the postsynaptic cell. It is shown here that BOAA also behaves as an NMDA agonist, and produces an effect very similar to that of BMAA on the postsynaptic response. In response to a single stimulus, the amplitude of the NMDA component is decreased, while the time to peak and duration of the NMDA component are greatly increased. No discernable effect on the AMPA component of the response was observed. Furthermore, both BMAA and BOAA cause an NMDAR-specific desensitization in response to repetitive stimulation at the physiological frequency for the postsynaptic cell (5 Hz). The possibility that this phenomenon may represent a response to excessive Ca(2+) entry through NMDAR channels is discussed. This desensitization phenomenon, as well as the abnormal NMDAR gating characteristics induced by BMAA, appears to be rescued during higher frequency stimulation (e.g. 10, 20 Hz).

  11. Response of L-alanine and 2-methylalanine minidosimeters for K-Band (24 GHz) EPR dosimetry

    NASA Astrophysics Data System (ADS)

    Chen, F.; Graeff, C. F. O.; Baffa, O.

    2007-11-01

    Minidosimeters of L-alanine and 2-methylalanine (2MA) were prepared and tested as potential candidates for small radiation field dosimetry. To quantify the free radicals created by radiation a K-Band (24 GHz) EPR spectrometer was used. X-rays provided by a 6 MV clinical linear accelerator were used to irradiate the minidosimeters in the dose range of 0.5-30 Gy. The dose-response curves for both radiation sensitive materials displayed a good linear behavior in the dose range indicated with 2MA being more radiation sensitive than L-alanine. Moreover, 2MA showed a smaller LLD (lower limit detection) value. The proposed system minidosimeter/K-Band spectrometer was able to detect 10 Gy EPR spectra with good signal-to-noise ratio (S/N). The overall uncertainty indicates that this system shows a good performance for the detection of dose values of 20 Gy and above, which are dose values typically used in radiosurgery treatments.

  12. Synthesis, growth, thermal, optical and mechanical properties of new organic NLO crystal: L-alanine DL-malic acid

    NASA Astrophysics Data System (ADS)

    Jaikumar, D.; Kalainathan, S.; Bhagavanarayana, G.

    2009-12-01

    A new organic nonlinear optical crystal, L-alanine DL-malic acid (LADLMA), has been grown from aqueous solution by the slow cooling technique. L-alanine and DL-malic acid were used in the ratio 2:1 for synthesis. Crystals of size 24×13×8 mm 3 have been obtained in 26 days. Characterizations were carried out to study the structural, optical and mechanical properties of the grown crystals. Single crystal X-ray diffraction analysis shows that they belong to the orthorhombic system. To study the crystalline perfection of the grown crystals, high-resolution X-ray diffraction (HR-XRD) study was carried out. The vibrational frequencies of various functional groups have been derived from FTIR spectrum. Thermal behaviour of the crystal was investigated by TG-DTA analyses. Transmission spectrum has been recorded in the solution state and the cut-off frequency has been determined. Nonlinear optical property of the crystal has been confirmed using the Kurtz powder technique and a study of its second harmonic generation efficiency in comparison with KDP has been made. Knoop hardness test was carried out and its Young's modulus was calculated.

  13. Crystal Engineering of l-Alanine with l-Leucine Additive using Metal-Assisted and Microwave-Accelerated Evaporative Crystallization

    PubMed Central

    2015-01-01

    In this work, we demonstrated that the change in the morphology of l-alanine crystals can be controlled with the addition of l-leucine using the metal-assisted and microwave accelerated evaporative crystallization (MA-MAEC) technique. Crystallization experiments, where an increasing stoichiometric amount of l-leucine is added to initial l-alanine solutions, were carried out on circular poly(methyl methacrylate) (PMMA) disks modified with a 21-well capacity silicon isolator and silver nanoparticle films using microwave heating (MA-MAEC) and at room temperature (control experiments). The use of the MA-MAEC technique afforded for the growth of l-alanine crystals with different morphologies up to ∼10-fold faster than those grown at room temperature. In addition, the length of l-alanine crystals was systematically increased from ∼380 to ∼2000 μm using the MA-MAEC technique. Optical microscope images revealed that the shape of l-alanine crystals was changed from tetragonal shape (without l-leucine additive) to more elongated and wire-like structures with the addition of the l-leucine additive. Further characterization of l-alanine crystals was undertaken by Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy and powder X-ray diffraction (PXRD) measurements. In order to elucidate the growth mechanism of l-alanine crystals, theoretical simulations of l-alanine’s morphology with and without l-leucine additive were carried out using Materials Studio software in conjunction with our experimental data. Theoretical simulations revealed that the growth of l-alanine’s {011} and {120} crystal faces were inhibited due to the incorporation of l-leucine into these crystal faces in selected positions. PMID:24839404

  14. Expression of the alaE gene is positively regulated by the global regulator Lrp in response to intracellular accumulation of l-alanine in Escherichia coli.

    PubMed

    Ihara, Kohei; Sato, Kazuki; Hori, Hatsuhiro; Makino, Yumiko; Shigenobu, Shuji; Ando, Tasuke; Isogai, Emiko; Yoneyama, Hiroshi

    2017-04-01

    The alaE gene in Escherichia coli encodes an l-alanine exporter that catalyzes the active export of l-alanine using proton electrochemical potential. In our previous study, alaE expression was shown to increase in the presence of l-alanyl-l-alanine (Ala-Ala). In this study, the global regulator leucine-responsive regulatory protein (Lrp) was identified as an activator of the alaE gene. A promoter less β-galactosidase gene was fused to an alaE upstream region (240 nucleotides). Cells that were lacZ-deficient and harbored this reporter plasmid showed significant induction of β-galactosidase activity (approximately 17-fold) in the presence of 6 mM l-alanine, l-leucine, and Ala-Ala. However, a reporter plasmid possessing a smaller alaE upstream region (180 nucleotides) yielded transformants with strikingly low enzyme activity under the same conditions. In contrast, lrp-deficient cells showed almost no β-galactosidase induction, indicating that Lrp positively regulates alaE expression. We next performed an electrophoretic mobility shift assay (EMSA) and a DNase I footprinting assay using purified hexahistidine-tagged Lrp (Lrp-His). Consequently, we found that Lrp-His binds to the alaE upstream region spanning nucleotide -161 to -83 with a physiologically relevant affinity (apparent KD, 288.7 ± 83.8 nM). Furthermore, the binding affinity of Lrp-His toward its cis-element was increased by l-alanine and l-leucine, but not by Ala-Ala and d-alanine. Based on these results, we concluded that the gene expression of the alaE is regulated by Lrp in response to intracellular levels of l-alanine, which eventually leads to intracellular homeostasis of l-alanine concentrations.

  15. β-methylamino-L-alanine (BMAA) is not found in the brains of patients with confirmed Alzheimer’s disease

    PubMed Central

    Meneely, Julie P.; Chevallier, Olivier P.; Graham, Stewart; Greer, Brett; Green, Brian D.; Elliott, Christopher T.

    2016-01-01

    Controversy surrounds the proposed hypothesis that exposure to β-methylamino-L-alanine (BMAA) could play a role in various neurodegenerative conditions including Alzheimer’s disease (AD). Here we present the results of the most comprehensive scientific study on BMAA detection ever undertaken on brain samples from patients pathologically confirmed to have suffered from AD, and those from healthy volunteers. Following the full validation of a highly accurate and sensitive mass spectrometric method, no trace of BMAA was detected in the diseased brain or in the control specimens. This contradicts the findings of other reports and calls into question the significance of this compound in neurodegenerative disease. We have attempted to explain the potential causes of misidentification of BMAA in these studies. PMID:27821863

  16. β-methylamino-L-alanine (BMAA) is not found in the brains of patients with confirmed Alzheimer's disease.

    PubMed

    Meneely, Julie P; Chevallier, Olivier P; Graham, Stewart; Greer, Brett; Green, Brian D; Elliott, Christopher T

    2016-11-08

    Controversy surrounds the proposed hypothesis that exposure to β-methylamino-L-alanine (BMAA) could play a role in various neurodegenerative conditions including Alzheimer's disease (AD). Here we present the results of the most comprehensive scientific study on BMAA detection ever undertaken on brain samples from patients pathologically confirmed to have suffered from AD, and those from healthy volunteers. Following the full validation of a highly accurate and sensitive mass spectrometric method, no trace of BMAA was detected in the diseased brain or in the control specimens. This contradicts the findings of other reports and calls into question the significance of this compound in neurodegenerative disease. We have attempted to explain the potential causes of misidentification of BMAA in these studies.

  17. 1H NMR determination of beta-N-methylamino-L-alanine (L-BMAA) in environmental and biological samples.

    PubMed

    Moura, Sidnei; Ultramari, Mariah de Almeida; de Paula, Daniela Mendes Louzada; Yonamine, Mauricio; Pinto, Ernani

    2009-04-01

    A nuclear magnetic resonance (1H NMR) method for the determination of beta-N-methylamino-L-alanine (L-BMAA) in environmental aqueous samples was developed and validated. L-BMAA is a neurotoxic modified amino acid that can be produced by cyanobacteria in aqueous environments. This toxin was extracted from samples by means of solid-phase extraction (SPE) and identified and quantified by 1H NMR without further derivatization steps. The lower limit of quantification (LLOQ) was 5 microg/mL. Good inter and intra-assay precision was also observed (relative standard deviation <8.5%) with the use of 4-nitro-DL-phenylalanine as an internal standard (IS). This method of 1H NMR analysis is not time consuming and can be readily utilized to monitor L-BMAA and confirm its presence in environmental and biological samples.

  18. Effect of Nickel sulphate on Growth, Structural, Optical, Mechanical and thermal properties of L-alanine Single Crystals (LANS)

    NASA Astrophysics Data System (ADS)

    Jothimani, R.; Selvarajan, P.

    2017-08-01

    The nonlinear optical materials find excellent place in frequency conversion, optical telecommunication, image processing, optical computing, and data storage. Due to possessing chiral symmetry and nature of crystallize in noncentro-symmetric space groups, the amino acids are applicable in NLO applications. A transparent nickel sulphate admixtured L-alanine crystal has been developed by solution method. X ray diffraction analysis depicts the orthorhombic crystal system of the sample. NLO efficiency of the sample was found to be highly pronounced compare to KDP. An enhanced linear optical property of the sample shows its suitability for NLO applications. Thermal behaviour of the sample was found by TGA/DTA analysis. Hardness parameters were also found for the sample by microhardness measurements. Laser damage threshold were also measured using Nd: YAG laser.

  19. Neurotoxic Non-proteinogenic Amino Acid β-N-Methylamino-L-alanine and Its Role in Biological Systems.

    PubMed

    Popova, A A; Koksharova, O A

    2016-08-01

    Secondary metabolites of photoautotrophic organisms have attracted considerable interest in recent years. In particular, molecules of non-proteinogenic amino acids participating in various physiological processes and capable of producing adverse ecological effects have been actively investigated. For example, the non-proteinogenic amino acid β-N-methylamino-L-alanine (BMAA) is neurotoxic to animals including humans. It is known that BMAA accumulation via the food chain can lead to development of neurodegenerative diseases in humans such as Alzheimer's and Parkinson's diseases as well as amyotrophic lateral sclerosis. Moreover, BMAA can be mistakenly incorporated into a protein molecule instead of serine. Natural sources of BMAA and methods for its detection are discussed in this review, as well as the role of BMAA in metabolism of its producers and possible mechanisms of toxicity of this amino acid in different living organisms.

  20. Environmental modulation of microcystin and β-N-methylamino-L-alanine as a function of nitrogen availability.

    PubMed

    Scott, L L; Downing, S; Phelan, R R; Downing, T G

    2014-09-01

    The most significant modulators of the cyanotoxins microcystin and β-N-methylamino-L-alanine in laboratory cyanobacterial cultures are the concentration of growth-medium combined nitrogen and nitrogen uptake rate. The lack of field studies that support these observations led us to investigate the cellular content of these cyanotoxins in cyanobacterial bloom material isolated from a freshwater impoundment and to compare these to the combined nitrogen availability. We established that these toxins typically occur in an inverse relationship in nature and that their presence is mainly dependent on the environmental combined nitrogen concentration, with cellular microcystin present at exogenous combined nitrogen concentrations of 29 μM and higher and cellular BMAA correlating negatively with exogenous nitrogen at concentrations below 40 μM. Furthermore, opposing nutrient and light gradients that form in dense cyanobacterial blooms may result in both microcystin and BMAA being present at a single sampling site.

  1. β-methylamino-L-alanine (BMAA) is not found in the brains of patients with confirmed Alzheimer’s disease

    NASA Astrophysics Data System (ADS)

    Meneely, Julie P.; Chevallier, Olivier P.; Graham, Stewart; Greer, Brett; Green, Brian D.; Elliott, Christopher T.

    2016-11-01

    Controversy surrounds the proposed hypothesis that exposure to β-methylamino-L-alanine (BMAA) could play a role in various neurodegenerative conditions including Alzheimer’s disease (AD). Here we present the results of the most comprehensive scientific study on BMAA detection ever undertaken on brain samples from patients pathologically confirmed to have suffered from AD, and those from healthy volunteers. Following the full validation of a highly accurate and sensitive mass spectrometric method, no trace of BMAA was detected in the diseased brain or in the control specimens. This contradicts the findings of other reports and calls into question the significance of this compound in neurodegenerative disease. We have attempted to explain the potential causes of misidentification of BMAA in these studies.

  2. Raman and neutron scattering study of partially deuterated L-alanine: evidence of a solid-solid phase transition.

    PubMed

    de Souza, Joelma M; Freire, Paulo T C; Argyriou, Dimitri N; Stride, John A; Barthès, Mariette; Kalceff, Walter; Bordallo, Heloisa N

    2009-12-21

    Raman and neutron experiments using specific isotope labeling were combined in order to study the dynamics and structure of L-alanine. Inelastic neutron and Raman scattering data of C(2)H(4)(ND(2))CO(2)D are discussed in relation to the doubling of the lattice parameter a observed by means of neutron powder diffraction in C(2)D(4) (NH(2))CO(2)H. The major changes accompanying the phase transition are found in the vibrational frequencies involving the torsional vibration tau(CO(2)(-)), which is clearly affected by the hydrogen bonds between the protons of the ammonium group and the oxygen atoms of the carboxylate group. At lower temperatures the rearrangement of identifiable hydrogen bonds induces changes in the bending vibration delta(ND(3)), confirming some orientational disorder.

  3. Vibrational spectral characterization, NLO studies and charge transfer analysis of the organometallic material L-Alanine cadmium chloride

    NASA Astrophysics Data System (ADS)

    Arun Sasi, B. S.; Bright, K. C.; James, C.

    2016-01-01

    An organometallic nonlinear crystal, L-Alanine Cadmium Chloride (LACC) was synthesized by slow evaporation technique. The effects of hydrogen bonding on the structure, binding of ligand to metal ion, natural orbital occupancies, and vibrational frequencies were investigated using density functional theory (DFT) with the combined B3LYP and LANL2DZ basis set. Vibrational assignments were made on the basis of calculated potential energy distribution values from MOLVIB program. The topological analysis of electron localization function (ELF) provides basin population N (integrated density over the attractor basin), standard deviation (σ), and their relative fluctuation, defined as λ = σ2/N, which are sensitive criteria of delocalization. The molecular stability, electronic exchange interaction, and bond strength of the molecule were studied by natural bond orbital (NBO) analysis. The second harmonic generation (SHG) efficiency was determined using Kurtz and Perry method. Natural bond orbital analysis was carried out to study various intramolecular interactions that are responsible for the stabilization of the molecule.

  4. An optical overview of poly[μ(2)-L-alanine-μ(3)-nitrato-sodium(I)] crystals.

    PubMed

    Gallegos-Loya, E; Orrantia-Borunda, E; Duarte-Moller, A

    2012-01-01

    Single crystals of the semiorganic materials, L-alanine sodium nitrate (LASN) and D-alanine sodium nitrate (DASN), were grown from an aqueous solution by slow-evaporation technique. X-ray diffraction (XRD) studies were carried for the doped grown crystals. The absorption of these grown crystals was analyzed using UV-Vis-NIR studies, and it was found that these crystals possess minimum absorption from 200 to 1100 nm. An infrared (FTIR) spectrum of single crystal has been measured in the 4000-400 cm(-1) range. The assignment of the observed vibrational modes to corresponding symmetry type has been performed. A thermogravimetric study was carried out to determine the thermal properties of the grown crystal. The efficiency of second harmonic generation was obtained by a variant of the Kurtz-Perry method.

  5. Intramolecular vibrations in low-frequency normal modes of amino acids: L-alanine in the neat solid state.

    PubMed

    Zhang, Feng; Wang, Houng-Wei; Tominaga, Keisuke; Hayashi, Michitoshi

    2015-03-26

    This paper presents a theoretical analysis of the low-frequency phonons of L-alanine by using the solid-state density functional theory at the Γ point. We are particularly interested in the intramolecular vibrations accessing low-frequency phonons via harmonic coupling with intermolecular vibrations. A new mode-analysis method is introduced to quantify the vibrational characteristics of such intramolecular vibrations. We find that the torsional motions of COO(-) are involved in low-frequency phonons, although COO(-) is conventionally assumed to undergo localized torsion. We also find the broad distributions of intramolecular vibrations relevant to important functional groups of amino acids, e.g., the COO(-) and NH3(+) torsions, in the low-frequency phonons. The latter finding is illustrated by the concept of frequency distribution of vibrations. These findings may lead to immediate implications in other amino acid systems.

  6. Molecular dynamics simulations of mutated Mycobacterium tuberculosis L-alanine dehydrogenase to illuminate the role of key residues.

    PubMed

    Ling, Baoping; Bi, Siwei; Sun, Min; Jing, Zhihong; Li, Xiaoping; Zhang, Rui

    2014-05-01

    L-Alanine dehydrogenase from Mycobacterium tuberculosis (L-MtAlaDH) catalyzes the NADH-dependent interconversion of l-alanine and pyruvate, and it is considered to be a potential target for the treatment of tuberculosis. The experiment has verified that amino acid replacement of the conserved active-site residues which have strong stability and no great changes in biological evolutionary process, such as His96 and Asp270, could lead to inactive mutants [Ågren et al., J. Mol. Biol. 377 (2008) 1161-1173]. However, the role of these conserved residues in catalytic reaction still remains unclear. Based on the crystal structures, a series of mutant structures were constructed to investigate the role of the conserved residues in enzymatic reaction by using molecular dynamics simulations. The results show that whatever the conserved residues were mutated, the protein can still convert its conformation from open state to closed state as long as NADH is present in active site. Asp270 maintains the stability of nicotinamide ring and ribose of NADH through hydrogen bond interactions, and His96 is helpful to convert the protein conformation by interactions with Gln271, whereas, they would lead to the structural rearrangement in active site and lose the catalytic activity when they were mutated. Additionally, we deduce that Met301 plays a major role in catalytic reaction due to fixing the nicotinamide ring of NADH to prevent its rotation, and we propose that Met301 would be mutated to the hydrophobic residue with large steric hindrance in side chain to test the activity of the protein in future experiment.

  7. Enantioselective Collision-Activated Dissociation of Gas-Phase Tryptophan Induced by Chiral Recognition of Protonated l-Alanine Peptides

    NASA Astrophysics Data System (ADS)

    Fujihara, Akimasa; Matsuyama, Hiroki; Tajiri, Michiko; Wada, Yoshinao; Hayakawa, Shigeo

    2017-06-01

    Enantioselective dissociation in the gas phase is important for enantiomeric enrichment and chiral transmission processes in molecular clouds regarding the origin of homochirality in biomolecules. Enantioselective collision-activated dissociation (CAD) of tryptophan (Trp) and the chiral recognition ability of l-alanine peptides ( l-Ala n ; n = 2-4) were examined using a linear ion trap mass spectrometer. CAD spectra of gas-phase heterochiral H+( d-Trp)( l-Ala n ) and homochiral H+( l-Trp)( l-Ala n ) noncovalent complexes were obtained as a function of the peptide size n. The H2O-elimination product was observed in CAD spectra of both heterochiral and homochiral complexes for n = 2 and 4, and in homochiral H+( l-Trp)( l-Ala3), indicating that the proton is attached to the l-alanine peptide, and H2O loss occurs from H+( l-Ala n ) in the noncovalent complexes. H2O loss did not occur in heterochiral H+( d-Trp)( l-Ala3), where NH3 loss and (H2O + CO) loss were the primary dissociation pathways. In heterochiral H+( d-Trp)( l-Ala3), the protonation site is the amino group of d-Trp, and NH3 loss and (H2O + CO) loss occur from H+( d-Trp). l-Ala peptides recognize d-Trp through protonation of the amino group for peptide size n = 3. NH3 loss and (H2O + CO) loss from H+( d-Trp) proceeds via enantioselective CAD in gas-phase heterochiral H+( d-Trp)( l-Ala3) at room temperature, whereas l-Trp dissociation was not observed in homochiral H+( l-Trp)( l-Ala3). These results suggest that enantioselective dissociation induced by chiral recognition of l-Ala peptides through protonation could play an important role in enantiomeric enrichment and chiral transmission processes of amino acids.

  8. Self-Assembly, Supramolecular Organization, and Phase Behavior of L-Alanine Alkyl Esters (n = 9-18) and Characterization of Equimolar L-Alanine Lauryl Ester/Lauryl Sulfate Catanionic Complex.

    PubMed

    Sivaramakrishna, D; Swamy, Musti J

    2015-09-08

    A homologous series of l-alanine alkyl ester hydrochlorides (AEs) bearing 9-18 C atoms in the alkyl chain have been synthesized and characterized with respect to self-assembly, supramolecular structure, and phase transitions. The CMCs of AEs bearing 11-18 C atoms were found to range between 0.1 and 10 mM. Differential scanning calorimetric (DSC) studies showed that the transition temperatures (Tt), enthalpies (ΔHt) and entropies (ΔSt) of AEs in the dry state exhibit odd-even alternation, with the odd-chain-length compounds having higher Tt values, but the even-chain-length homologues showing higher values of ΔHt and ΔSt. In DSC measurements on hydrated samples, carried out at pH 5.0 and pH 10.0 (where they exist in cationic and neutral forms, respectively), compounds with 13-18 C atoms in the alkyl chain showed sharp gel-to-liquid crystalline phase transitions, and odd-even alternation was not seen in the thermodynamic parameters. The molecular structure, packing properties, and intermolecular interactions of AEs with 9 and 10 C atoms in the alkyl chain were determined by single crystal X-ray diffraction, which showed that the alkyl chains are packed in a tilted interdigitated bilayer format. d-Spacings obtained from powder X-ray diffraction studies exhibited a linear dependence on the alkyl chain length, suggesting that the other AEs also adopt an interdigitated bilayer structure. Turbidimetric, fluorescence spectroscopic, and isothermal titration calorimetric (ITC) studies established that in aqueous dispersions l-alanine lauryl ester hydrochloride (ALE·HCl) and sodium dodecyl sulfate (SDS) form an equimolar complex. Transmission electron microscopic and DSC studies indicate that the complex exists as unilamellar liposomes, which exhibit a sharp phase transition at ∼39 °C. The aggregates were disrupted at high pH, suggesting that the catanionic complex would be useful to develop a base-labile drug delivery system. ITC studies indicated that ALE·HCl forms

  9. Heterogeneity of L-alanine transport systems in brush-border membrane vesicles from rat placenta during late gestation.

    PubMed Central

    Alonso-Torre, S R; Serrano, M A; Medina, J M; Alvarado, F

    1992-01-01

    The placental uptake of L-alanine was studied by using purified brush-border membrane vesicles from rat trophoblasts. Saturation curves were carried out at 37 degrees C in buffers containing 100 mM (zero-trans)-NaSCN, -NaCl, -KSCN, -KCl, or -N-methyl-D-glucamine gluconate. The uncorrected uptake results were fitted by non-linear regression analysis to an equation involving one diffusional component either one or two saturable Michaelian transport terms. In the presence of NaCl, two distinct L-alanine transport systems were distinguished, named respectively System 1 (S-1; Vm1 about 760 pmol/s per mg of protein; KT1 = 0.5 mM) and System 2 (S-2; Vm2 about 1700 pmol/s per mg; KT2 = 9 mM). In contrast, in the presence of K+ (KCl = KSCN) or in the absence of any alkali-metal ions (N-methyl-D-glucamine gluconate), only one saturable system was apparent, which we identify as S-2. When Na+ is present, S-1, but not S-2, appears to be rheogenic, since its maximal transport capacity significantly increases in the presence of an inside-negative membrane potential, created either by replacing Cl- with the permeant anion thiocyanate (NaSCN > NaCl) or by applying an appropriate K+ gradient and valinomycin. alpha-(Methylamino)isobutyrate (methyl-AIB) appears to be a substrate of S-1, but not of S-2. For reasons that remain to be explained, however, methyl-AIB inhibits S-2. We conclude that S-1 represents a truly Na(+)-dependent mechanism, where Na+ behaves as an obligatory activator, whereas S-2 cannot discriminate between Na+ and K+, although its activity is higher in the presence of alkali-metal ions than in their absence (Na+ = K+ > N-methyl-D-glucammonium ion). S-2 appears to be fully developed 2 days before birth, whereas S-1 undergoes a capacity-type activation between days 19.5 and 21.5 of gestation, i.e. its apparent Vmax. nearly doubles, whereas its KT remains constant. PMID:1445280

  10. l-glutamine and l-alanine supplementation increase glutamine-glutathione axis and muscle HSP-27 in rats trained using a progressive high-intensity resistance exercise.

    PubMed

    Leite, Jaqueline Santos Moreira; Raizel, Raquel; Hypólito, Thaís Menezes; Rosa, Thiago Dos Santos; Cruzat, Vinicius Fernandes; Tirapegui, Julio

    2016-08-01

    In this study we investigated the chronic effects of oral l-glutamine and l-alanine supplementation, either in their free or dipeptide form, on glutamine-glutathione (GLN-GSH) axis and cytoprotection mediated by HSP-27 in rats submitted to resistance exercise (RE). Forty Wistar rats were distributed into 5 groups: sedentary; trained (CTRL); and trained supplemented with l-alanyl-l-glutamine, l-glutamine and l-alanine in their free form (GLN+ALA), or free l-alanine (ALA). All trained animals were submitted to a 6-week ladder-climbing protocol. Supplementations were offered in a 4% drinking water solution for 21 days prior to euthanasia. Plasma glutamine, creatine kinase (CK), myoglobin (MYO), and erythrocyte concentration of reduced GSH and glutathione disulfide (GSSG) were measured. In tibialis anterior skeletal muscle, GLN-GSH axis, thiobarbituric acid reactive substances (TBARS), and the expression of heat shock factor 1 (HSF-1), 27-kDa heat shock protein (HSP-27), and glutamine synthetase were determined. In CRTL animals, high-intensity RE reduced muscle glutamine levels and increased GSSG/GSH rate and TBARS, as well as augmented plasma CK and MYO levels. Conversely, l-glutamine-supplemented animals showed an increase in plasma and muscle levels of glutamine, with a reduction in GSSG/GSH rate, TBARS, and CK. Free l-alanine administration increased plasma glutamine concentration and lowered muscle TBARS. HSF-1 and HSP-27 were high in all supplemented groups when compared with CTRL (p < 0.05). The results presented herein demonstrate that l-glutamine supplemented with l-alanine, in both a free or dipeptide form, improve the GLN-GSH axis and promote cytoprotective effects in rats submitted to high-intensity RE training.

  11. The effect of β-N-methylamino-L-alanine (BMAA) on oxidative stress response enzymes of the macrophyte Ceratophyllum demersum.

    PubMed

    Esterhuizen-Londt, M; Pflugmacher, S; Downing, T G

    2011-04-01

    Cyanobacteria are known to produce bioactive secondary metabolites such as hepatotoxins, cytotoxins and neurotoxins. The newly recognized neurotoxin β-N-methylamino-L-alanine (BMAA) is a naturally occurring non-protein amino acid found in the majority of cyanobacterial genera tested. Evidence that exists for implication of BMAA in neurodegenerative disorders relies on bioaccumulation and biomagnification from symbiotic cyanobacteria. Uptake and accumulation of free BMAA by various non-symbiotic organisms, including aquatic macrophytes, has been documented but to date limited evidence of ecotoxicology exists. We therefore investigated the effect of BMAA on the oxidative stress responses of the macrophyte, Ceratophyllum demersum. Markers for oxidative stress in this study are the antioxidative enzymes superoxide dismutase, catalase, guaiacol peroxidase, glutathione peroxidase and glutathione reductase. We found that BMAA had an inhibitory effect on all the oxidative stress response enzymes tested in plants exposed to BMAA. However enzymes not related to oxidative stress response were not affected by BMAA in in vitro experiments. Binding studies in the presence of BMAA showed reduced enzyme specific activity over time compared to the control. This study shows that BMAA causes oxidative stress indirectly as it inhibits antioxidant enzymes required to combat reactive oxygen species that cause damage to cells. Further investigations are required to fully understand the inhibitory effect of BMAA on these enzymes. Copyright © 2011 Elsevier Ltd. All rights reserved.

  12. Equilibrium Dynamics of β-N-Methylamino-L-Alanine (BMAA) and Its Carbamate Adducts at Physiological Conditions

    PubMed Central

    Zimmerman, David; Goto, Joy J.; Krishnan, Viswanathan V

    2016-01-01

    Elevated incidences of Amyotrophic Lateral Sclerosis/Parkinsonism Dementia complex (ALS/PDC) is associated with β-methylamino-L-alanine (BMAA), a non-protein amino acid. In particular, the native Chamorro people living in the island of Guam were exposed to BMAA by consuming a diet based on the cycad seeds. Carbamylated forms of BMAA are glutamate analogues. The mechanism of neurotoxicity of the BMAA is not completely understood, and BMAA acting as a glutamate receptor agonist may lead to excitotoxicity that interferes with glutamate transport systems. Though the interaction of BMAA with bicarbonate is known to produce carbamate adducts, here we demonstrate that BMAA and its primary and secondary adducts coexist in solution and undergoes a chemical exchange among them. Furthermore, we determined the rates of formation/cleavage of the carbamate adducts under equilibrium conditions using two-dimensional proton exchange NMR spectroscopy (EXSY). The coexistence of the multiple forms of BMAA at physiological conditions adds to the complexity of the mechanisms by which BMAA functions as a neurotoxin. PMID:27513925

  13. The effect of exogenous β-N-methylamino-l-alanine (BMAA) on the diatoms Phaeodactylum tricornutum and Thalassiosira weissflogii.

    PubMed

    Lage, Sandra; Ström, Linnea; Godhe, Anna; Rydberg, Sara

    2016-09-01

    β-N-methylamino-l-alanine (BMAA), a non-protein amino acid with neurodegenerative features, is known to be produced by cyanobacteria, diatoms and a dinoflagellate. BMAA research has intensified over the last decade, and knowledge has been gained about its bioaccumulation in aquatic and terrestrial ecosystems, toxic effects in model organisms and neurotoxicity in vivo and in vitro. Nevertheless, knowledge of the actual physiological role of BMAA in the producing species or of the ecological factors that regulate BMAA production is still lacking. A few studies propose that BMAA functions to signal nitrogen depletion in cyanobacteria. To investigate whether BMAA might have a similar role in diatoms, two diatom species - Phaeodactylum tricornutum and Thalassiosira weissflogii - were exposed to exogenous BMAA at environmental relevant concentrations, i.e. 0.005, 0.05 and 0.5μM. BMAA was taken up in a concentration dependent manner in both species in the BMAA free fraction and in the protein fraction of T. weissflogii. As a result of the treatments, the diatom cells at some of the time points and at some of the BMAA concentrations exhibited lower concentrations of chlorophyll a and protein, in comparison to controls. At the highest (0.5μM) concentration of BMAA, extracellular ammonia was found in the media of both species at all time points. These results suggest that BMAA interferes with nitrogen metabolism in diatoms, possibly by inhibiting ammonium assimilation via the GS/GOGAT pathway.

  14. Quantitative proteomics analysis of zebrafish exposed to sub-lethal dosages of β-methyl-amino-L-alanine (BMAA)

    PubMed Central

    Frøyset, Ann Kristin; Khan, Essa Ahsan; Fladmark, Kari Espolin

    2016-01-01

    The non-protein amino acid β-methylamino-L-alanine (BMAA) is a neurotoxin present in microalgae and shown to accumulate in the food web. BMAA has been linked to the complex neurodegenerative disorder of Guam and to increased incidents sporadic ALS. Two main neurotoxic routes are suggested; an excitotoxic by acting as an agonist towards glutamate receptors and a metabolic by misincorporating into cellular proteins. We have used zebrafish, an increasingly used model for neurodegenerative diseases, to further identify signaling components involved in BMAA-induced toxicity. Zebrafish embryos were exposed to sub-lethal dosages of BMAA and a label-free proteomics analysis was conducted on larvae 4 days post fertilization. The exposed larvae showed no developmental abnormalities, but a reduced heart rate and increased expression of GSK3 isoforms. Search towards a reviewed database containing 2968 entries identified 480 proteins. Only 17 of these were regulated 2-fold or more in the exposed larvae. Seven of these proteins could be associated to glutamate receptor signaling and recycling. The remaining nine have all been linked to disturbance in protein homeostasis, reactive oxygen species (ROS) development or neuronal cell death. We also found that BMAA influenced the endocannabinoid system by up-regulation of fatty acid amide hydrolase (FAAH) and that FAAH inhibitor URB597 reduced the BMAA effect on heart rate and GSK3 expression. PMID:27404450

  15. Reaction Pathways and Kinetics of a Cyanobacterial Neurotoxin β-N-Methylamino-L-Alanine (BMAA) during Chlorination.

    PubMed

    Chen, Yi-Ting; Chen, Wan-Ru; Liu, Zhi-Quan; Lin, Tsair-Fuh

    2017-02-07

    β-N-Methylamino-L-alanine (BMAA), a probable cause of the amyotrophic lateral sclerosis/parkinsonism-dementia complex (ALS/PDC), or Alzheimer's disease, has been identified in more than 20 cyanobacterial genera. However, its removal and fate in drinking water has never been reported before. In this study, the reaction of BMAA with chlorine, a common drinking-water oxidant/disinfectant, was investigated. A liquid chromatograph coupled with a triple quadrupole mass spectrometer was employed to quantify BMAA and its intermediates. Upon chlorination, four chlorinated intermediates, each with one or two chlorines, were identified. The disappearance of BMAA caused by chlorine follows a second-order reaction, with the rate constant k1 is 5.0 × 10(4) M(-1) s(-1) at pH ∼7.0. The chlorinated intermediates were found to further react with free chlorine, exhibiting a second-order rate constant k3 = 16.8 M(-1) s(-1). After all free chlorine was consumed, the chlorinated intermediates autodecomposed slowly with a first order rate constant k2 = 0.003 min(-1); when a reductant was added, these chlorinated intermediates were then reduced back to BMAA. The results as described shed a useful light on the reactivity, appearance, and removal of BMAA in the chlorination process of a drinking-water system.

  16. Equilibrium Dynamics of β-N-Methylamino-L-Alanine (BMAA) and Its Carbamate Adducts at Physiological Conditions.

    PubMed

    Zimmerman, David; Goto, Joy J; Krishnan, Viswanathan V

    2016-01-01

    Elevated incidences of Amyotrophic Lateral Sclerosis/Parkinsonism Dementia complex (ALS/PDC) is associated with β-methylamino-L-alanine (BMAA), a non-protein amino acid. In particular, the native Chamorro people living in the island of Guam were exposed to BMAA by consuming a diet based on the cycad seeds. Carbamylated forms of BMAA are glutamate analogues. The mechanism of neurotoxicity of the BMAA is not completely understood, and BMAA acting as a glutamate receptor agonist may lead to excitotoxicity that interferes with glutamate transport systems. Though the interaction of BMAA with bicarbonate is known to produce carbamate adducts, here we demonstrate that BMAA and its primary and secondary adducts coexist in solution and undergoes a chemical exchange among them. Furthermore, we determined the rates of formation/cleavage of the carbamate adducts under equilibrium conditions using two-dimensional proton exchange NMR spectroscopy (EXSY). The coexistence of the multiple forms of BMAA at physiological conditions adds to the complexity of the mechanisms by which BMAA functions as a neurotoxin.

  17. The use of L-serine to prevent β-methylamino-L-alanine (BMAA)-induced proteotoxic stress in vitro.

    PubMed

    Main, Brendan J; Dunlop, Rachael A; Rodgers, Kenneth J

    2016-01-01

    β-methylamino-L-alanine (BMAA), a non-protein amino acid synthesised by cyanobacteria, has been linked to a complex neurological disorder on Guam and more recently to other cases of sporadic ALS (sALS), however the mechanisms of BMAA toxicity are not completely understood. We have previously demonstrated that BMAA is misincorporated into newly synthesised proteins by human neuroblastoma cells and fibroblasts, resulting in the formation of autofluorescent material and the induction of apoptotic cell death. In the present study we show that BMAA at low levels does not cause an acute toxicity in neuroblastoma cells but increases the expression of the ER stress marker, C/EBP homologous protein (CHOP) and increases the activity of the pro-apoptotic enzyme caspase-3. We also observed an increase in the activity of the lysosomal cysteine proteases cathepsin B and L, characteristic of the accumulation of proteins in the lysosomal system. We were able to prevent these proteotoxic effects in neuroblastoma cells through co-treatment with l-serine suggesting that they resulted from incorporation of BMAA into proteins. Misincorporation provides a possible mechanism whereby BMAA could initiate misfolding, and the accumulation of aggregate-prone proteins in neurons. This build-up of misfolded proteins could explain the long latency period of the disease previously reported on Guam.

  18. Quantitative proteomics analysis of zebrafish exposed to sub-lethal dosages of β-methyl-amino-L-alanine (BMAA).

    PubMed

    Frøyset, Ann Kristin; Khan, Essa Ahsan; Fladmark, Kari Espolin

    2016-07-12

    The non-protein amino acid β-methylamino-L-alanine (BMAA) is a neurotoxin present in microalgae and shown to accumulate in the food web. BMAA has been linked to the complex neurodegenerative disorder of Guam and to increased incidents sporadic ALS. Two main neurotoxic routes are suggested; an excitotoxic by acting as an agonist towards glutamate receptors and a metabolic by misincorporating into cellular proteins. We have used zebrafish, an increasingly used model for neurodegenerative diseases, to further identify signaling components involved in BMAA-induced toxicity. Zebrafish embryos were exposed to sub-lethal dosages of BMAA and a label-free proteomics analysis was conducted on larvae 4 days post fertilization. The exposed larvae showed no developmental abnormalities, but a reduced heart rate and increased expression of GSK3 isoforms. Search towards a reviewed database containing 2968 entries identified 480 proteins. Only 17 of these were regulated 2-fold or more in the exposed larvae. Seven of these proteins could be associated to glutamate receptor signaling and recycling. The remaining nine have all been linked to disturbance in protein homeostasis, reactive oxygen species (ROS) development or neuronal cell death. We also found that BMAA influenced the endocannabinoid system by up-regulation of fatty acid amide hydrolase (FAAH) and that FAAH inhibitor URB597 reduced the BMAA effect on heart rate and GSK3 expression.

  19. The cyanobacterial neurotoxin β-N-methylamino-l-alanine (BMAA) induces neuronal and behavioral changes in honeybees.

    PubMed

    Okle, Oliver; Rath, Lisa; Galizia, C Giovanni; Dietrich, Daniel R

    2013-07-01

    The cyanobacterially produced neurotoxin beta-N-methylamino-l-alanine (BMAA) is thought to induce amyotrophic lateral sclerosis/Parkinsonism dementia complex (ALS/PDC)-like symptoms. However, its mechanism of action and its pathway of intoxication are yet unknown. In vivo animal models suitable for investigating the neurotoxic effect of BMAA with applicability to the human are scarce. Hence, we used the honeybee (Apis mellifera) since its nervous system is relatively simple, yet having cognitive capabilities. Bees fed with BMAA-spiked sugar water had an increased mortality rate and a reduced ability to learn odors in a classical conditioning paradigm. Using (14)C-BMAA we demonstrated that BMAA is biologically available to the bee, and is found in the head, thorax and abdomen with little to no excretion. BMAA is also transferred from one bee to the next via trophallaxis resulting in an exposure of the whole beehive. BMAA bath application directly onto the brain leads to an altered Ca(2+) homeostasis and to generation of reactive oxygen species. These behavioral and physiological observations suggest that BMAA may have effects on bee brains similar to those assumed to occur in humans. Therefore the bee could serve as a surrogate model system for investigating the neurological effects of BMAA.

  20. The Arabidopsis thaliana isogene NIT4 and its orthologs in tobacco encode beta-cyano-L-alanine hydratase/nitrilase.

    PubMed

    Piotrowski, M; Schönfelder, S; Weiler, E W

    2001-01-26

    Nitrilases (nitrile aminohydrolases, EC ) are enzymes that catalyze the hydrolysis of nitriles to the corresponding carbon acids. Among the four known nitrilases of Arabidopsis thaliana, the isoform NIT4 is the most divergent one, and homologs of NIT4 are also known from species not belonging to the Brassicaceae like Nicotiana tabacum and Oryza sativa. We expressed A. thaliana NIT4 as hexahistidine tag fusion protein in Escherichia coli. The purified enzyme showed a strong substrate specificity for beta-cyano-l-alanine (Ala(CN)), an intermediate product of cyanide detoxification in higher plants. Interestingly, not only aspartic acid but also asparagine were identified as products of NIT4-catalyzed Ala(CN) hydrolysis. Asn itself was no substrate for NIT4, indicating that it is not an intermediate but one of two reaction products. NIT4 therefore has both nitrilase and nitrile hydratase activity. Several lines of evidence indicate that the catalytic center for both reactions is the same. The NIT4 homologs of N. tabacum were found to catalyze the same reactions and protein extracts of A. thaliana, N. tabacum and Lupinus angustifolius also converted Ala(CN) to Asp and Asn in vitro. NIT4 may play a role in cyanide detoxification during ethylene biosynthesis because extracts from senescent leaves of A. thaliana showed higher Ala(CN) hydratase/nitrilase activities than extracts from nonsenescent tissue.

  1. New Typical Vector of Neurotoxin β-N-Methylamino-l-Alanine (BMAA) in the Marine Benthic Ecosystem.

    PubMed

    Li, Aifeng; Song, Jialiang; Hu, Yang; Deng, Longji; Ding, Ling; Li, Meihui

    2016-11-04

    The neurotoxin β-N-methylamino-l-alanine (BMAA) has been identified as an environmental factor triggering neurodegenerative diseases such as Amyotrophic Lateral Sclerosis (ALS) and Alzheimer's disease (AD). We investigated the possible vectors of BMAA and its isomers 2,4-diaminobutyric acid (DAB) and N-2(aminoethyl)glycine (AEG) in marine mollusks collected from the Chinese coast. Sixty-eight samples of marine mollusks were collected along the Chinese coast in 2016, and were analyzed by an HILIC-MS/MS (hydrophilic interaction liquid chromatography with tandem quadrupole mass spectrometer) method without derivatization. BMAA was detected in a total of five samples from three species: Neverita didyma, Solen strictus, and Mytilus coruscus. The top three concentrations of free-form BMAA (0.99~3.97 μg·g(-1) wet weight) were detected in N. didyma. DAB was universally detected in most of the mollusk samples (53/68) with no species-specific or regional differences (0.051~2.65 μg·g(-1) wet weight). No AEG was detected in any mollusk samples tested here. The results indicate that the gastropod N. didyma might be an important vector of the neurotoxin BMAA in the Chinese marine ecosystem. The neurotoxin DAB was universally present in marine bivalve and gastropod mollusks. Since N. didyma is consumed by humans, we suggest that the origin and risk of BMAA and DAB toxins in the marine ecosystem should be further investigated in the future.

  2. Cell therapy for skin wound using fibroblast encapsulated poly(ethylene glycol)-poly(L-alanine) thermogel.

    PubMed

    Yun, Eun Jung; Yon, Bora; Joo, Min Kyung; Jeong, Byeongmoon

    2012-04-09

    As a new application of a thermogel, a poly(ethylene glycol)-b-poly(L-alanine) (PEG-L-PA) gel encapsulating fibroblasts was investigated for wound healing. The fibroblasts were encapsulated by the temperature sensitive sol-to-gel transition of the polymer aqueous solution. Under the in vitro three-dimensional (3D) cell culture condition, the PEG-L-PA thermogel was comparable with Matrigel for cell proliferation and was significantly better than Matrigel for collagen types I and III formation. After confirming the excellent 3D microenvironment of the PEG-L-PA thermogel for fibroblasts, in vivo wound healing was investigated by injecting the cell-suspended polymer aqueous solution on incisions of rat skin, where the cell-encapsulated gel was formed in situ. Compared with the phosphate buffered saline treated system and the cell-free PEG-L-PA thermogel, the cell-encapsulated PEG-L-PA thermogel not only accelerated the wound closure but also improved epithelialization and the formation of skin appendages such as keratinocyte layer (epidermis), hair follicles, and sebaceous glands. The results demonstrate the potential of thermogels for cell therapy as an injectable tissue-engineering scaffold.

  3. Dietary exposure and neurotoxicity of the environmental free and bound toxin β-N-methylamino-l-alanine.

    PubMed

    Regueiro, Jorge; Negreira, Noelia; Carreira-Casais, Anxo; Pérez-Lamela, Conchi; Simal-Gándara, Jesús

    2017-10-01

    The growing evidence supporting a link between exposure to the naturally occurring toxin β-N-methylamino-l-alanine (BMAA) and progressive neurodegenerative diseases, has recently arisen the interest of the scientific community. Latest investigations suggest that dietary exposure to this algal toxin may have been largely underestimated. This paper reviews the state of the art regarding BMAA, with special attention paid to its neurotoxicity, its concentration levels in food, and human exposure. As for other environmental toxins, dietary intake is most likely the main route of exposure to BMAA for the general population. However, data concerning BMAA levels in foodstuffs are still scarce. It is concluded that further investigations on dietary intake and potential human health effects are clearly necessary to assess the risks to public health associated with BMAA exposure. Some critical remarks and recommendations on future research in this area are provided, which may help to identify approaches to reduce dietary BMAA exposure. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Growth, structural, spectral, mechanical, thermal and dielectric characterization of phosphoric acid admixtured L-alanine (PLA) single crystals

    NASA Astrophysics Data System (ADS)

    Rose, A. S. J. Lucia; Selvarajan, P.; Perumal, S.

    2011-10-01

    Phosphoric acid admixtured L-alanine (PLA) single crystals were grown successfully by solution method with slow evaporation technique at room temperature. Crystals of size 18 mm × 12 mm × 8 mm have been obtained in 28 days. The grown crystals were colorless and transparent. The solubility of the grown samples has been found out at various temperatures. The lattice parameters of the grown crystals were determined by X-ray diffraction technique. The reflection planes of the sample were confirmed by the powder X-ray diffraction study and diffraction peaks were indexed. Fourier transform infrared (FTIR) studies were used to confirm the presence of various functional groups in the crystals. UV-visible transmittance spectrum was recorded to study the optical transparency of grown crystal. The nonlinear optical (NLO) property of the grown crystal was confirmed by Kurtz-Perry powder technique and a study of its second harmonic generation efficiency in comparison with potassium dihydrogen phosphate (KDP) has been made. The mechanical strength of the crystal was estimated by Vickers hardness test. The grown crystals were subjected to thermo gravimetric and differential thermal analysis (TG/DTA). The dielectric behavior of the sample was also studied.

  5. Growth, structural, spectral, mechanical, thermal and dielectric characterization of phosphoric acid admixtured L-alanine (PLA) single crystals.

    PubMed

    Rose, A S J Lucia; Selvarajan, P; Perumal, S

    2011-10-15

    Phosphoric acid admixtured L-alanine (PLA) single crystals were grown successfully by solution method with slow evaporation technique at room temperature. Crystals of size 18 mm×12 mm×8 mm have been obtained in 28 days. The grown crystals were colorless and transparent. The solubility of the grown samples has been found out at various temperatures. The lattice parameters of the grown crystals were determined by X-ray diffraction technique. The reflection planes of the sample were confirmed by the powder X-ray diffraction study and diffraction peaks were indexed. Fourier transform infrared (FTIR) studies were used to confirm the presence of various functional groups in the crystals. UV-visible transmittance spectrum was recorded to study the optical transparency of grown crystal. The nonlinear optical (NLO) property of the grown crystal was confirmed by Kurtz-Perry powder technique and a study of its second harmonic generation efficiency in comparison with potassium dihydrogen phosphate (KDP) has been made. The mechanical strength of the crystal was estimated by Vickers hardness test. The grown crystals were subjected to thermo gravimetric and differential thermal analysis (TG/DTA). The dielectric behavior of the sample was also studied.

  6. Influence of L-alanine doping on crystalline perfection, SHG efficiency, optical and mechanical properties of KDP single crystals

    NASA Astrophysics Data System (ADS)

    Shakir, Mohd.; Ganesh, V.; Riscob, B.; Maurya, K. K.; Wahab, M. A.; Bhagavannarayana, G.; Kishan Rao, K.

    2011-09-01

    Pure and L-alanine (LA) doped single crystals of potassium dihydrogen orthophosphate (KDP) were grown by slow evaporation solution technique (SEST) in aqueous solution at ambient temperature. Powder X-ray diffraction study was done to confirm the crystal system and lattice parameters of KDP. No additional phases were observed at all doping concentrations (1-7.5 mol%), which was further confirmed by FT-Raman spectroscopy analysis. The influence of LA doping on the crystalline perfection was assessed by high-resolution X-ray diffractometry (HRXRD) analysis. HRXRD studies revealed that the grown crystals could accommodate LA at the interstitial positions in the crystalline matrix of KDP up to some critical concentration without any deterioration in the crystalline perfection. Above this concentration, very low angle structural grain boundaries were developed and it seems that the excess LA above the critical concentration was segregated along the grain boundaries. The SHG efficiency was measured using the Kurtz powder technique. The relative SHG efficiency of the crystals was found to be increased with doping concentration up to 5 mol% and above this it decreases. Optical transmission study also revealed the same behavior with enhancement up to 5 mol% concentration and later decreased. The hardness values were found to be increased by increasing the doping concentration.

  7. β-N-methylamino-L-alanine (BMAA) uptake by the animal model, Daphnia magna and subsequent oxidative stress.

    PubMed

    Esterhuizen-Londt, Maranda; Wiegand, Claudia; Downing, Tim G

    2015-06-15

    β-N-methylamino-l-alanine (BMAA), produced by cyanobacteria, is a neurotoxin implicated in Amyotrophic lateral sclerosis/Parkinsonism dementia complex (ALS/PDC). BMAA concentrations in cyanobacteria are lower than those thought to be necessary to result in neurological damage thus bioaccumulation or biomagnification is required to achieve concentrations able to cause neurodegeneration. Many cyanobacteria produce BMAA and uptake routes into the food web require examination. In this study we investigate the uptake of BMAA by adult phytoplanktivorus Daphnia magna via exposure to dissolved pure BMAA and BMAA containing cyanobacteria, as well as the subsequent oxidative stress response in the daphnia. Free BMAA and protein-associated BMAA were quantified by LC-MS/MS. Dissolved BMAA was taken up and was found as free BMAA in D. magna. No protein-associated BMAA was detected in D. magna after a 24-h exposure period. No BMAA was detectable in D. magna after exposure to BMAA containing cyanobacteria. BMAA inhibited the oxidative stress defence and biotransformation enzymes within 24-h exposure in the tested Daphnia and could therefore impair the oxidant status and the capability of detoxifying other substances in D. magna.

  8. New Typical Vector of Neurotoxin β-N-Methylamino-l-Alanine (BMAA) in the Marine Benthic Ecosystem

    PubMed Central

    Li, Aifeng; Song, Jialiang; Hu, Yang; Deng, Longji; Ding, Ling; Li, Meihui

    2016-01-01

    The neurotoxin β-N-methylamino-l-alanine (BMAA) has been identified as an environmental factor triggering neurodegenerative diseases such as Amyotrophic Lateral Sclerosis (ALS) and Alzheimer’s disease (AD). We investigated the possible vectors of BMAA and its isomers 2,4-diaminobutyric acid (DAB) and N-2(aminoethyl)glycine (AEG) in marine mollusks collected from the Chinese coast. Sixty-eight samples of marine mollusks were collected along the Chinese coast in 2016, and were analyzed by an HILIC-MS/MS (hydrophilic interaction liquid chromatography with tandem quadrupole mass spectrometer) method without derivatization. BMAA was detected in a total of five samples from three species: Neverita didyma, Solen strictus, and Mytilus coruscus. The top three concentrations of free-form BMAA (0.99~3.97 μg·g−1 wet weight) were detected in N. didyma. DAB was universally detected in most of the mollusk samples (53/68) with no species-specific or regional differences (0.051~2.65 μg·g−1 wet weight). No AEG was detected in any mollusk samples tested here. The results indicate that the gastropod N. didyma might be an important vector of the neurotoxin BMAA in the Chinese marine ecosystem. The neurotoxin DAB was universally present in marine bivalve and gastropod mollusks. Since N. didyma is consumed by humans, we suggest that the origin and risk of BMAA and DAB toxins in the marine ecosystem should be further investigated in the future. PMID:27827914

  9. The cyanobacterial neurotoxin beta-N-methylamino-L-alanine (BMAA) induces neuronal and behavioral changes in honeybees

    SciTech Connect

    Okle, Oliver; Rath, Lisa; Galizia, C. Giovanni; Dietrich, Daniel R.

    2013-07-01

    The cyanobacterially produced neurotoxin beta-N-methylamino-L-alanine (BMAA) is thought to induce amyotrophic lateral sclerosis/Parkinsonism dementia complex (ALS/PDC)-like symptoms. However, its mechanism of action and its pathway of intoxication are yet unknown. In vivo animal models suitable for investigating the neurotoxic effect of BMAA with applicability to the human are scarce. Hence, we used the honeybee (Apis mellifera) since its nervous system is relatively simple, yet having cognitive capabilities. Bees fed with BMAA-spiked sugar water had an increased mortality rate and a reduced ability to learn odors in a classical conditioning paradigm. Using {sup 14}C-BMAA we demonstrated that BMAA is biologically available to the bee, and is found in the head, thorax and abdomen with little to no excretion. BMAA is also transferred from one bee to the next via trophallaxis resulting in an exposure of the whole beehive. BMAA bath application directly onto the brain leads to an altered Ca{sup 2+} homeostasis and to generation of reactive oxygen species. These behavioral and physiological observations suggest that BMAA may have effects on bee brains similar to those assumed to occur in humans. Therefore the bee could serve as a surrogate model system for investigating the neurological effects of BMAA. - Highlights: • Investigating of neurotoxic effects of BMAA in honeybees • BMAA impairs ALS markers (ROS, Ca{sup 2+}, learning, memory, odor) in bees. • A method for the observation of ROS development in living bees brain was established. • Honeybees are a suitable model to explore neurodegenerative processes. • Neurotoxic BMAA can be spread in bee populations by trophallaxis.

  10. The effect of exogenous β-N-methylamino-L: -alanine on the growth of Synechocystis PCC6803.

    PubMed

    Downing, Simoné; van de Venter, Maryna; Downing, Timothy G

    2012-01-01

    β-N-Methylamino-L: -alanine (BMAA), a non-proteinogenic amino acid, has been detected in a range of cyanobacteria, including terrestrial, aquatic, free living and endosymbiotic species. The widespread occurrence of cyanobacteria in the environment raises concerns regarding the ecological and toxicological impact of BMAA, and consequently, studies have focussed extensively on the toxicity and environmental impact of BMAA, while no research has addressed the ecophysiological or metabolic role of the compound in cyanobacteria. In this study, both the uptake of exogenous BMAA by and the effect of exogenous BMAA on the growth of Synechocystis PCC6803 were investigated. BMAA was rapidly taken up by the non-diazotrophic cyanobacterium Synechocystis PCC6803 in a concentration dependent manner. The presence of exogenous BMAA resulted in a substantial and concentration-dependent decrease in cell growth and the substantial loss of photosynthetic pigmentation. Similar effects were seen in the presence of the non-proteinogenic amino acid, 2,4-diaminobutyric acid but to a lesser degree than that of BMAA. The effects were reversed when light was decreased from 16 to 10 μmol m(-2) s(-1). Control cultures grown in the presence of L: -arginine, L: -asparagine, L: -glutamate and glycine showed normal or slightly increased growth with no change in pigmentation. The decrease in growth rate coupled to bleaching indicates that BMAA may induce chlorosis in the presence of adequate photosynthetic radiation suggesting a connection between BMAA and the induction of conditions, such as nitrogen or sulphur depletion, that result in growth arrest and the induction of chlorosis.

  11. The natural non-protein amino acid N-β-methylamino-L-alanine (BMAA) is incorporated into protein during synthesis.

    PubMed

    Glover, W Broc; Mash, Deborah C; Murch, Susan J

    2014-11-01

    N-β-methylamino-L-alanine (BMAA) is an amino acid produced by cyanobacteria and accumulated through trophic levels in the environment and natural food webs. Human exposure to BMAA has been linked to progressive neurodegenerative diseases, potentially due to incorporation of BMAA into protein. The insertion of BMAA and other non-protein amino acids into proteins may trigger protein misfunction, misfolding and/or aggregation. However, the specific mechanism by which BMAA is associated with proteins remained unidentified. Such studies are challenging because of the complexity of biological systems and samples. A cell-free in vitro protein synthesis system offers an excellent approach for investigation of changing amino acid composition in protein. In this study, we report that BMAA incorporates into protein as an error in synthesis when a template DNA sequence is used. Bicinchoninic acid assay of total protein synthesis determined that BMAA effectively substituted for alanine and serine in protein product. LC-MS/MS confirmed that BMAA was selectively inserted into proteins in place of other amino acids, but isomers N-(2-aminoethyl)glycine (AEG) and 2,4-diaminobutyric acid (DAB) did not share this characteristic. Incorporation of BMAA into proteins was significantly higher when genomic DNA from post-mortem brain was the template. About half of BMAA in the synthetic proteins was released with denaturation with sodium dodecylsulfonate and dithiothreitol, but the remaining BMAA could only be released by acid hydrolysis. Together these data demonstrate that BMAA is incorporated into the amino acid backbone of proteins during synthesis and also associated with proteins through non-covalent bonding.

  12. Maternal transfer of the cyanobacterial neurotoxin β-N-methylamino-L-alanine (BMAA) via milk to suckling offspring.

    PubMed

    Andersson, Marie; Karlsson, Oskar; Bergström, Ulrika; Brittebo, Eva B; Brandt, Ingvar

    2013-01-01

    The cyanobacterial neurotoxin β-N-methylamino-L-alanine (BMAA) has been implicated in the etiology of neurodegenerative disease and proposed to be biomagnified in terrestrial and aquatic food chains. We have previously shown that the neonatal period in rats, which in humans corresponds to the last trimester of pregnancy and the first few years of age, is a particularly sensitive period for exposure to BMAA. The present study aimed to examine the secretion of (14)C-labeled L- and D-BMAA into milk in lactating mice and the subsequent transfer of BMAA into the developing brain. The results suggest that secretion into milk is an important elimination pathway of BMAA in lactating mothers and an efficient exposure route predominantly for L-BMAA but also for D-BMAA in suckling mice. Following secretion of [(14)C]L-BMAA into milk, the levels of [(14)C]L-BMAA in the brains of the suckling neonatal mice significantly exceeded the levels in the maternal brains. In vitro studies using the mouse mammary epithelial HC11 cell line confirmed a more efficient influx and efflux of L-BMAA than of D-BMAA in cells, suggesting enantiomer-selective transport. Competition experiments with other amino acids and a low sodium dependency of the influx suggests that the amino acid transporters LAT1 and LAT2 are involved in the transport of L-BMAA into milk. Given the persistent neurodevelopmental toxicity following injection of L-BMAA to neonatal rodent pups, the current results highlight the need to determine whether BMAA is enriched mother's and cow's milk.

  13. Global cellular responses to β-methyl-amino-L-alanine (BMAA) by olfactory ensheathing glial cells (OEC).

    PubMed

    Chiu, Alexander S; Braidy, Nady; Marçal, Helder; Welch, Jeffrey H; Gehringer, Michelle M; Guillemin, Gilles J; Neilan, Brett A

    2015-06-01

    This study utilised a proteomics approach to identify any differential protein expression in a glial cell line, rat olfactory ensheathing cells (OECs), treated with the cyanotoxin β-methylamino-l-alanine (BMAA). Five proteins of interest were identified, namely Rho GDP-dissociation inhibitor 1 (RhoGDP1), Nck-associated protein 1 (NCKAP1), voltage-dependent anion-selective channel protein 1 (VDAC1), 3-hydroxyacyl-CoA dehydrogenase type-2 (3hCoAdh2), and ubiquilin-4 (UBQLN4). Four of these candidates, nuclear receptor subfamily 4 group A member 1 (Nur77), cyclophilin A (CyPA), RhoGDP1 and VDAC1, have been reported to be involved in cell growth. A microarray identified UBQLN4, palladin and CyPA, which have been implicated to have roles in excitotoxicity. Moreover, the NCKAP1, UBQLN4, CyPA and 3hCoAdh2 genes have been associated with abnormal protein aggregation. Differential expression of genes involved in mitochondrial activity, Nur77, 3hCoAdh2, VDAC1 and UBQLN4, were also identified. Confirmatory reverse transcription quantitative PCR (RT-qPCR) analysis of transcripts generated from the genes of interest corroborated the differential expression trends identified in the global protein analysis. BMAA induced cell cycle arrest in the G2/M phase of OEC and apoptosis after 48 h at concentrations of 250 μM and 500 μM. Collectively, this work advances our understanding of the mechanism of BMAA-mediated glial-toxicity in vitro.

  14. Development of an analytical procedure for quantifying the underivatized neurotoxin β-N-methylamino-L-alanine in brain tissues.

    PubMed

    Combes, Audrey; El Abdellaoui, Saïda; Vial, Jérome; Lagrange, Emmeline; Pichon, Valérie

    2014-07-01

    The cyanotoxin β-methylamino-L-alanine (BMAA) has received renewed attention as an environmental risk factor for sporadic cases of amyotrophic lateral sclerosis (ALS) (Nunn et al., Brain Res 410:375-379, 1987). The aim of the present study was to develop and to validate an analytical procedure that allows the quantification of native BMAA and of its natural isomer, 2,4 diaminobutyric acid (DAB), in brain tissues. An analytical procedure was previously reported by our group for the determination of underivatized BMAA in environmental samples. It included a step of sample clean-up by solid phase extraction (SPE) with a mixed-mode sorbent and the analyses were performed by LC/MS-MS using hydrophilic interaction chromatography and multiple reactions monitoring scan mode. As brain tissues have a higher lipid content, the crucial step of sample clean-up had been optimized by evaluating the efficiency of the addition of a liquid/liquid extraction step prior to the SPE procedure or alternatively, of washing steps to the SPE extraction procedure. The efficiency was checked by visualizing the complexity of the resulting chromatograms in LC/MS and their performance by using spiked brain samples. The optimized analytical procedure, including a washing step with cyclohexane to the SPE with a recovery yield close to 100%, was validated using the total error approach and allowed the quantification of BMAA in a concentration level ranging from 20 to 1,500 ng/g in brain samples. Finally, the feasibility of implementation of this procedure was verified in human brain samples from two patients who died of ALS.

  15. Synthesis of a molecularly imprinted sorbent for selective solid-phase extraction of β-N-methylamino-L-alanine.

    PubMed

    Svoboda, Pavel; Combes, Audrey; Petit, Julia; Nováková, Lucie; Pichon, Valérie

    2015-11-01

    The aim of the work was to synthesize a molecularly imprinted material for the selective solid-phase extraction (SPE) of β-N-methylamino-L-alanine (L-2-amino-3-methylpropionic acid; BMAA) from cyanobacterial extracts. BMAA and its structural analogs that can be used as template are small, polar and hydrophilic molecules. These molecules are poorly soluble in organic solvents that are commonly used for the synthesis of acrylic-based polymers. Therefore, a sol gel approach was chosen to carry out the synthesis and the resulting sorbents were evaluated with different extraction procedures in order to determine their ability to selectively retain BMAA. The presence of imprinted cavities in the sorbent was demonstrated by comparing elution profiles obtained by using molecularly imprinted silica (MIS) and non-imprinted silica (NIS) as a control. The molecularly imprinted solid-phase extraction (MISPE) procedure was first developed in a pure medium (acetonitrile) and further optimized for the treatment of cyanobacterial samples. It was characterized by high elution recoveries (89% and 77% respectively in pure and in real media).The repeatability of the extraction procedure in pure medium, in real medium and the reproducibility of MIS synthesis all expressed as RSD values of extraction recovery of BMAA were equal to 3%, 12% and 5%, respectively. A MIS capacity of 0.34 µmol/g was measured. The matrix effects, which affected the quantification of BMAA when employing a mixed mode sorbent, were completely removed by adding a clean-up step of the mixed-mode sorbent extract on the MIS.

  16. N-β-Methylamino-L-Alanine and Its Naturally Occurring Isomers in Cyanobacterial Blooms in Lake Winnipeg.

    PubMed

    Bishop, Stephanie L; Kerkovius, Jeff K; Menard, Frederic; Murch, Susan J

    2017-09-30

    Cyanobacterial blooms have affected Lake Winnipeg since the mid-1990s due to an increased phosphorus loading into the lake, which has been exacerbated by stressors such as climate change and eutrophication. Aquatic ecosystems involving cyanobacteria have been found to contain N-β-methylamino-L-alanine (BMAA) and 2,4-diaminobutyric acid (DAB), non-protein amino acids that are associated with neurodegenerative disease, as well as two of the naturally occurring isomers, N-2(amino)ethylglycine (AEG) and β-amino-N-methylalanine (BAMA). We hypothesized that the cyanobacterial bloom in Lake Winnipeg produces BMAA and/or its naturally occurring isomers. Samples of cyanobacteria were collected by the Lake Winnipeg Research Consortium from standard sampling stations and blooms in July and September of 2016 and were analyzed for BMAA, DAB, AEG, and BAMA using previously published validated analytical methods. BMAA and BAMA were found in the highest concentration in the center of the north basin, the deepest and lowest-nitrogen zone of the lake, at an average concentration of 4 μg/g (collected in July and September 2016) and 1.5 mg/g (collected in July 2016), respectively. AEG and DAB were found in the highest concentration in cyanobacterial blooms from the nearshore region of the north basin, the slightly shallower and more nitrogen-rich zone of the lake, at 2.1 mg/g (collected in July 2016) and 0.2 mg/g (collected in July and September 2016), respectively. These findings indicate that the production of non-protein amino acids varies with the depth and nutrient contents of the bloom. It is important to note that we did not measure food or water samples directly and further study of the Lake Winnipeg food web is required to determine whether BMAA bioaccumulation represents an increased risk factor for neurodegenerative disease in the region.

  17. Maternal Transfer of the Cyanobacterial Neurotoxin β-N-Methylamino-L-Alanine (BMAA) via Milk to Suckling Offspring

    PubMed Central

    Andersson, Marie; Karlsson, Oskar; Bergström, Ulrika; Brittebo, Eva B.; Brandt, Ingvar

    2013-01-01

    The cyanobacterial neurotoxin β-N-methylamino-L-alanine (BMAA) has been implicated in the etiology of neurodegenerative disease and proposed to be biomagnified in terrestrial and aquatic food chains. We have previously shown that the neonatal period in rats, which in humans corresponds to the last trimester of pregnancy and the first few years of age, is a particularly sensitive period for exposure to BMAA. The present study aimed to examine the secretion of 14C-labeled L- and D-BMAA into milk in lactating mice and the subsequent transfer of BMAA into the developing brain. The results suggest that secretion into milk is an important elimination pathway of BMAA in lactating mothers and an efficient exposure route predominantly for L-BMAA but also for D-BMAA in suckling mice. Following secretion of [14C]L-BMAA into milk, the levels of [14C]L-BMAA in the brains of the suckling neonatal mice significantly exceeded the levels in the maternal brains. In vitro studies using the mouse mammary epithelial HC11 cell line confirmed a more efficient influx and efflux of L-BMAA than of D-BMAA in cells, suggesting enantiomer-selective transport. Competition experiments with other amino acids and a low sodium dependency of the influx suggests that the amino acid transporters LAT1 and LAT2 are involved in the transport of L-BMAA into milk. Given the persistent neurodevelopmental toxicity following injection of L-BMAA to neonatal rodent pups, the current results highlight the need to determine whether BMAA is enriched mother's and cow's milk. PMID:24194910

  18. Strong water-mediated friction asymmetry and surface dynamics of zwitterionic solids at ambient conditions: L-alanine as a case study

    NASA Astrophysics Data System (ADS)

    Segura, J. J.; Verdaguer, A.; Garzón, L.; Barrena, E.; Ocal, C.; Fraxedas, J.

    2011-03-01

    Water molecules strongly interact with freshly cleaved (011) surfaces of L-alanine single crystals at low relative humidity (below 10%) promoting diffusion of L-alanine molecules. Species mobility is enhanced above ˜40% leading to the formation of two-dimensional islands with long-range order through Ostwald ripening. Scanning force microscopy experiments reveal that both, islands and terraces, are identical in nature (composition and crystallographic structure) but a relevant friction asymmetry appearing upon water-surface interaction evidences that orientation dependent properties exist between them at the molecular level. We interpret this observation as due to water incorporation in the topmost surface crystal structure. Eventually, for high humidity values, surface dissolution and roughening occur.

  19. Strong water-mediated friction asymmetry and surface dynamics of zwitterionic solids at ambient conditions: L-alanine as a case study.

    PubMed

    Segura, J J; Verdaguer, A; Garzón, L; Barrena, E; Ocal, C; Fraxedas, J

    2011-03-28

    Water molecules strongly interact with freshly cleaved (011) surfaces of L-alanine single crystals at low relative humidity (below 10%) promoting diffusion of L-alanine molecules. Species mobility is enhanced above ~40% leading to the formation of two-dimensional islands with long-range order through Ostwald ripening. Scanning force microscopy experiments reveal that both, islands and terraces, are identical in nature (composition and crystallographic structure) but a relevant friction asymmetry appearing upon water-surface interaction evidences that orientation dependent properties exist between them at the molecular level. We interpret this observation as due to water incorporation in the topmost surface crystal structure. Eventually, for high humidity values, surface dissolution and roughening occur.

  20. Dipeptide Nanotubes Containing Unnatural Fluorine-Substituted β(2,3)-Diarylamino Acid and L-Alanine as Candidates for Biomedical Applications.

    PubMed

    Bonetti, Andrea; Pellegrino, Sara; Das, Priyadip; Yuran, Sivan; Bucci, Raffaella; Ferri, Nicola; Meneghetti, Fiorella; Castellano, Carlo; Reches, Meital; Gelmi, Maria Luisa

    2015-09-18

    The synthesis and the structural characterization of dipeptides composed of unnatural fluorine-substituted β(2,3)-diarylamino acid and L-alanine are reported. Depending on the stereochemistry of the β amino acid, these dipeptides are able to self-assemble into proteolytic stable nanotubes. These architectures were able to enter the cell and locate in the cytoplasmic/perinuclear region and represent interesting candidates for biomedical applications.

  1. Transferability and reproducibility in electron-density studies--bond-topological and atomic properties of tripeptides of the type L-alanyl-X-L-alanine.

    PubMed

    Grabowsky, Simon; Kalinowski, Roman; Weber, Manuela; Förster, Diana; Paulmann, Carsten; Luger, Peter

    2009-08-01

    In the last decade three different data bank approaches have been developed that are intended to make electron-density examinations of large biologically important molecules possible. They rely on Bader's concept of transferability of submolecular fragments with retention of their electronic properties. Therefore, elaborate studies on the quantification of transferability in experiment and theory are still very important. Tripeptides of the type L-alanyl-X-L-alanine (X being any of the 20 naturally encoded amino acids) serve as a model case between amino acids and proteins. The two experimental electron-density determinations (L-alanyl-L-histidinyl-L-alanine and L-alanyl-L-phenylalanyl-L-alanine, highly resolved synchrotron X-ray diffraction data sets) performed in this study and theoretical calculations on all 20 different L-alanyl-X-L-alanine molecules contribute to a better estimation of transferability in the peptide case. As a measure of reproducibility and transferability, standard deviations from averaging over bond-topological and atomic properties of atoms or bonds that are considered equal in their chemical environments were calculated. This way, transferability and reproducibility indices were introduced. It can be shown that experimental transferability indices generally slightly exceed experimental reproducibility indices and that these larger deviations can be attributed to chemical effects such as changes in the geometry (bond lengths and angles), the polarization pattern and the neighboring sphere due to crystal packing. These effects can partly be separated from each other and quantified with the help of gas-phase calculations at optimized and experimental geometries. Thus, the degree of transferability can be quantified in very narrow limits taking into account experimental errors and chemical effects.

  2. Polarised Raman and infrared spectral analysis of L-alanine oxalate (C5H9NO6)--a non-linear optical single crystal.

    PubMed

    Krishnakumar, V; Nagalakshmi, R

    2006-06-01

    L-alanine oxalate (C5H9NO6), a promising material for effective frequency conversion, was grown by standard slow evaporation technique. Solubility studies were carried out at different temperatures. Unambiguous assignments of fundamental modes of various molecular groups were made from the recorded infrared and polarised Raman spectra. The non-linear optical property has been confirmed from the optical transmission and fluorescence spectra.

  3. Comparison of the Tastes of L-Alanine and Monosodium Glutamate in C57BL/6J Wild Type and T1r3 Knockout Mice.

    PubMed

    Eddy, Meghan C; Eschle, Benjamin K; Delay, Eugene R

    2017-09-01

    Previous research showed that L-alanine and monosodium L-glutamate elicit similar taste sensations in rats. This study reports the results of behavioral experiments designed to compare the taste capacity of C57BL/6J wild type and T1r3- mice for these 2 amino acids. In conditioned taste aversion (CTA) experiments, wild-type mice exhibited greater sensitivity than knockout mice for both L-amino acids, although knockout mice were clearly able to detect both amino acids at 50 mM and higher concentrations. Generalization of CTA between L-alanine and L-glutamate was bidirectionally equivalent for both mouse genotypes, indicating that both substances elicited similar tastes in both genotypes. This was verified by the discrimination experiments in which both mouse genotypes performed at or near chance levels at 75 and 150 mM. Above 150 mM, discrimination performance improved, suggesting the taste qualities of the 2 L-amino acids are not identical. No differences between knockout and wild-type mice in discrimination ability were detected. These results indicate that while the T1r3 receptor is important for tasting L-alanine and L-glutamate, other receptors are also important for tasting these amino acids. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. Amino acids (L-arginine and L-alanine) passivated CdS nanoparticles: Synthesis of spherical hierarchical structure and nonlinear optical properties

    NASA Astrophysics Data System (ADS)

    Talwatkar, S. S.; Tamgadge, Y. S.; Sunatkari, A. L.; Gambhire, A. B.; Muley, G. G.

    2014-12-01

    CdS nanoparticles (NPs) passivated with amino acids (L-alanine and L-arginine) having spherical hierarchical morphology were synthesized by room temperature wet chemical method. Synthesized NPs were characterized by ultraviolet-visible (UV-vis) spectroscopy to study the variation of band gaps with concentration of surface modifying agents. Increase in band gap has been observed with the increase in concentration of surface modifying agents and was found more prominent for CdS NPs passivated with L-alanine. Powder X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis were carried out for the study of crystal structure and morphology of CdS NPs. The average particle size of CdS NPs calculated from Debye-Scherer formula was found to less than 5 nm and agrees well with those determined from UV-vis spectra and TEM data. Fourier transform infrared (FT-IR) spectroscopy was performed to know the functional groups of the grown NPs. Peaks in FT-IR spectra indicate the formation of CdS NPs and capping with L-alanine and L-arginine. Photoluminescence spectra of these NPs were also studied. Finally, colloidal solution of CdS-PVAc was subjected to Z-scan experiment under low power cw laser illumination to characterize them for third order nonlinear optical properties. CdS-PVAc colloidal solution shows enhanced nonlinear absorption due to RSA and weak FCA on account of two photon absorption processes triggered by thermal effect.

  5. Quantitative determination of the neurotoxin β-N-methylamino-L-alanine (BMAA) by capillary electrophoresis-tandem mass spectrometry.

    PubMed

    Kerrin, Elliott S; White, Robert L; Quilliam, Michael A

    2017-02-01

    Recent reports of the widespread occurrence of the neurotoxin β-N-methylamino-L-alanine (BMAA) in cyanobacteria and particularly seafood have raised concerns for public health. LC-MS/MS is currently the analytical method of choice for BMAA determinations but incomplete separation of isomeric and isobaric compounds, matrix suppression and conjugated forms are plausible limitations. In this study, capillary electrophoresis (CE) coupled with MS/MS has been developed as an alternative method for the quantitative determination of free BMAA. Using a bare fused silica capillary, a phosphate buffer (250 mM, pH 3.0) and UV detection, it was possible to separate BMAA from four isomers, but the limit of detection (LOD) of 0.25 μg mL(-1) proved insufficient for analysis of typical samples. Coupling the CE to a triple quadrupole MS was accomplished using a custom sheath-flow interface. The best separation was achieved with a 5 M formic acid in water/acetonitrile (9:1) background electrolyte. Strong acid hydrolysis of lyophilized samples was used to release BMAA from conjugated forms. Field-amplified stacking after injection was achieved by lowering sample ionic strength with a cation-exchange cleanup procedure. Quantitation was accomplished using isotope dilution with deuterium-labelled BMAA as internal standard. An LOD for BMAA in solution of 0.8 ng mL(-1) was attained, which was equivalent to 16 ng g(-1) dry mass in samples using the specified extraction procedure. This was comparable with LC-MS/MS methods. The method displayed excellent resolution of amino acid isomers and had no interference from matrix components. The presence of BMAA in cycad, mussel and lobster samples was confirmed by CE-MS/MS, but not in an in-house cyanobacterial reference material, with quantitative results agreeing with those from LC-MS/MS. Graphical Abstract CE-MS separation and detection of BMAA, its isomers and the internal standard BMAA-d3.

  6. Cycling time trial performance may be impaired by whey protein and L-alanine intake during prolonged exercise.

    PubMed

    Schroer, Adam B; Saunders, Michael J; Baur, Daniel A; Womack, Christopher J; Luden, Nicholas D

    2014-10-01

    Previous studies reported that adding protein (PRO) to carbohydrate (CHO) solutions enhances endurance performance. The ergogenic effect may be a function of additional protein/amino acid calories, but this has not been examined. In addition, although supplemental L-alanine (ALA) is readily oxidized during exercise, the subsequent impact on metabolism and prolonged endurance performance is unknown. The purpose of this investigation was to independently gauge the impact of whey PRO hydrolysate and ALA supplementation on performance and various physiological parameters. Eight cyclists (age: 22.3 ± 5.6 yr, weight: 70.0 ± 8.0 kg, VO2max: 59.4 ± 4.9 ml · kg(-1) · min(-1)) performed 120 min of constant-load cycling (55% of peak power) followed by a 30-km time trial (TT) under placebo (PLA), PRO, and ALA conditions. Magnitude-based qualitative inferences were applied to evaluate treatment differences and data are presented as percent difference between treatments ± 90% confidence limit. Both ALA (2.1 ± 2.7%) and PRO intake (-2.1 ± 2.2%) possibly harmed performance compared with PLA. Of interest, heart rate was possibly lower with ALA than PLA at 20- (-2.7 ± 3.4%) and 120-min (-1.7 ± 2.9%) of constant-load cycling and the serum interleukin-6 (IL-6) response to 120 min of cycling was likely attenuated with PRO compared with PLA (PLA, 6.6 ± 3.7 fold vs. PRO, 2.9 ± 1.8 fold). In addition, blood glucose levels were lower with PRO than PLA at 20- (-8.8 ± 2.3%; very likely) and 120-min (-4.9 ± 4.6%; likely) of constant-load cycling. Although ALA intake appears to lower HR and PRO ingestion dampens the IL-6 response to exercise, the ingestion of PRO (without CHO) or ALA does not enhance, and may actually impair, performance following prolonged cycling.

  7. Determination of the anti-inflammatory and cytoprotective effects of l-glutamine and l-alanine, or dipeptide, supplementation in rats submitted to resistance exercise.

    PubMed

    Raizel, Raquel; Leite, Jaqueline Santos Moreira; Hypólito, Thaís Menezes; Coqueiro, Audrey Yule; Newsholme, Philip; Cruzat, Vinicius Fernandes; Tirapegui, Julio

    2016-08-01

    We evaluated the effects of chronic oral supplementation with l-glutamine and l-alanine in their free form or as the dipeptide l-alanyl-l-glutamine (DIP) on muscle damage, inflammation and cytoprotection, in rats submitted to progressive resistance exercise (RE). Wistar rats (n 8/group) were submitted to 8-week RE, which consisted of climbing a ladder with progressive loads. In the final 21 d before euthanasia, supplements were delivered in a 4 % solution in drinking water. Glutamine, creatine kinase (CK), lactate dehydrogenase (LDH), TNF-α, specific IL (IL-1β, IL-6 and IL-10) and monocyte chemoattractant protein-1 (MCP-1) levels were evaluated in plasma. The concentrations of glutamine, TNF-α, IL-6 and IL-10, as well as NF-κB activation, were determined in extensor digitorum longus (EDL) skeletal muscle. HSP70 level was assayed in EDL and peripheral blood mononuclear cells (PBMC). RE reduced glutamine concentration in plasma and EDL (P<0·05 v. sedentary group). However, l-glutamine supplements (l-alanine plus l-glutamine (GLN+ALA) and DIP groups) restored glutamine levels in plasma (by 40 and 58 %, respectively) and muscle (by 93 and 105 %, respectively). GLN+ALA and DIP groups also exhibited increased level of HSP70 in EDL and PBMC, consistent with the reduction of NF-κB p65 activation and cytokines in EDL. Muscle protection was also indicated by attenuation in plasma levels of CK, LDH, TNF-α and IL-1β, as well as an increase in IL-6, IL-10 and MCP-1. Our study demonstrates that chronic oral l-glutamine treatment (given with l-alanine or as dipeptide) following progressive RE induces cyprotective effects mediated by HSP70-associated responses to muscle damage and inflammation.

  8. Identification and Partial Characterization of a Novel UDP-N-Acetylenolpyruvoylglucosamine Reductase/UDP-N-Acetylmuramate:l-Alanine Ligase Fusion Enzyme from Verrucomicrobium spinosum DSM 4136T

    PubMed Central

    Naqvi, Kubra F.; Patin, Delphine; Wheatley, Matthew S.; Savka, Michael A.; Dobson, Renwick C. J.; Gan, Han Ming; Barreteau, Hélène; Blanot, Didier; Mengin-Lecreulx, Dominique; Hudson, André O.

    2016-01-01

    The enzymes involved in synthesizing the bacterial cell wall are attractive targets for the design of antibacterial compounds, since this pathway is essential for bacteria and is absent in animals, particularly humans. A survey of the genome of a bacterium that belongs to the phylum Verrucomicrobia, the closest free-living relative to bacteria from the Chlamydiales phylum, shows genetic evidence that Verrucomicrobium spinosum possesses a novel fusion open reading frame (ORF) annotated by the locus tag (VspiD_010100018130). The ORF, which is predicted to encode the enzymes UDP-N-acetylenolpyruvoylglucosamine reductase (MurB) and UDP-N-acetylmuramate:l-alanine ligase (MurC) that are involved in the cytoplasmic steps of peptidoglycan biosynthesis, was cloned. In vivo analyses using functional complementation showed that the fusion gene was able to complement Escherichia coli murB and murC temperature sensitive mutants. The purified recombinant fusion enzyme (MurB/CVs) was shown to be endowed with UDP-N-acetylmuramate:l-alanine ligase activity. In vitro analyses demonstrated that the latter enzyme had a pH optimum of 9.0, a magnesium optimum of 10 mM and a temperature optimum of 44–46°C. Its apparent Km values for ATP, UDP-MurNAc, and l-alanine were 470, 90, and 25 μM, respectively. However, all attempts to demonstrate an in vitro UDP-N-acetylenolpyruvoylglucosamine reductase (MurB) activity were unsuccessful. Lastly, Hidden Markov Model-based similarity search and phylogenetic analysis revealed that this fusion enzyme could only be identified in specific lineages within the Verrucomicrobia phylum. PMID:27047475

  9. Cyanobacterial Blooms and the Occurrence of the neurotoxin beta-N-methylamino-L-alanine (BMAA) in South Florida Aquatic Food Webs.

    PubMed

    Brand, Larry E; Pablo, John; Compton, Angela; Hammerschlag, Neil; Mash, Deborah C

    2010-09-01

    Recent studies demonstrate that most cyanobacteria produce the neurotoxin beta-N-methylamino-L-alanine (BMAA) and that it can biomagnify in at least one terrestrial food chain. BMAA has been implicated as a significant environmental risk in the development of neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and Amyotrophic Lateral Sclerosis (ALS). We examined several blooms of cyanobacteria in South Florida, and the BMAA content of resident animals, including species used as human food. A wide range of BMAA concentrations were found, ranging from below assay detection limits to approximately 7000 μg/g, a concentration associated with a potential long-term human health hazard.

  10. FT-IR and Raman spectroscopic and DFT studies of anti-cancer active molecule N-{(meta-ferrocenyl) Benzoyl} - L-Alanine - Glycine ethyl ester

    NASA Astrophysics Data System (ADS)

    Xavier, T. S.; Kenny, Peter T. M.; Manimaran, D.; Joe, I. Hubert

    2015-06-01

    FT-Raman and FT-IR spectra of N-{(meta-ferrocenyl) Benzoyl} - L-alanine - glycine ethyl ester were recorded in solid phase. The optimized molecular geometry, the vibrational wavenumbers, the infrared intensities and the Raman scattering intensities were calculated by using density functional method(B3LYP) with 6-31G(d, p) basis set. Vibrational assignment of the molecule was done by using potential energy distribution analysis. Natural bond orbital analysis, Mulliken charge analysis and HOMO-LUMO energy were used to elucidate the reasons for intra molecular charge transfer. Docking studies were conducted to predict its anticancer activity.

  11. The effect of 100 MeV oxygen ion on electrical and optical properties of nonlinear optical l-alanine sodium nitrate single crystals

    SciTech Connect

    Ahlam, M. A.; Prakash, A. P. Gnana

    2012-06-05

    Single crystals of nonlinear optical (NLO) L-alanine Sodium Nitrate (LASN) were grown by slow evaporation method. The grown crystals were irradiated by 100 MeV oxygen ions with the cumulative doses of 1Mrad, 6 Mrad and 10 Mrad. The dielectric properties, differential scanning calorimetry (DSC) and second harmonic generation (SHG) of the crystals were studied before and after irradiation. The dielectric constant was found to increase after irradiation. The DSC reveals that the melting point remains unaffected due to irradiation. The SHG efficiency of LASN was found to decrease with increase in radiation dose.

  12. The structure of the O-polysaccharide from the lipopolysaccharide of Providencia stuartii O57 containing an amide of D-galacturonic acid with L-alanine.

    PubMed

    Kocharova, Nina A; Ovchinnikova, Olga G; Bushmarinov, Ivan S; Toukach, Filip V; Torzewska, Agnieszka; Shashkov, Alexander S; Knirel, Yuriy A; Rozalski, Antoni

    2005-03-21

    The O-polysaccharide (O-antigen) was obtained by mild acid degradation of the lipopolysaccharide of Providencia stuartii O57:H29. Studies by sugar and methylation analyses along with (1)H and (13)C NMR spectroscopy, including two-dimensional (1)H,(1)H COSY, TOCSY, ROESY, H-detected (1)H,(13)C HSQC, and HMBC experiments, showed that the polysaccharide contains an amide of D-galacturonic acid with L-alanine and has the following pentasaccharide repeating unit: [formula: see text

  13. Investigation of the nitrogen hyperfine coupling of the second stable radical in γ-irradiated L-alanine crystals by 2D-HYSCORE spectroscopy

    NASA Astrophysics Data System (ADS)

    Maltar-Strmečki, Nadica; Rakvin, Boris

    2012-09-01

    The second stable radical, NH3+C(CH3)COO, R2, in the γ-irradiated single crystal of L-alanine and its fully 15N-enriched analogue were studied by an advanced pulsed EPR technique, 2D-HYSCORE (two-dimensional hyperfine sublevel correlation) spectroscopy at 200 K. The nitrogen hyperfine coupling tensor of the R2 radical was determined from the HYSCORE data and provides new experimental data for improved characterization of the R2 radical in the crystal lattice. The results obtained complement the experimental proton data available for the R2 radical and could lead to increased accuracy and reliability of EPR spectrum simulations.

  14. The effect of 100 MeV oxygen ion on electrical and optical properties of nonlinear optical l-alanine sodium nitrate single crystals

    NASA Astrophysics Data System (ADS)

    Ahlam, M. A.; Prakash, A. P. Gnana

    2012-06-01

    Single crystals of nonlinear optical (NLO) L-alanine Sodium Nitrate (LASN) were grown by slow evaporation method. The grown crystals were irradiated by 100 MeV oxygen ions with the cumulative doses of 1Mrad, 6 Mrad and 10 Mrad. The dielectric properties, differential scanning calorimetry (DSC) and second harmonic generation (SHG) of the crystals were studied before and after irradiation. The dielectric constant was found to increase after irradiation. The DSC reveals that the melting point remains unaffected due to irradiation. The SHG efficiency of LASN was found to decrease with increase in radiation dose.

  15. Determination of the carbon, hydrogen and nitrogen contents of alanine and their uncertainties using the certified reference material L-alanine (NMIJ CRM 6011-a).

    PubMed

    Itoh, Nobuyasu; Sato, Ayako; Yamazaki, Taichi; Numata, Masahiko; Takatsu, Akiko

    2013-01-01

    The carbon, hydrogen, and nitrogen (CHN) contents of alanine and their uncertainties were estimated using a CHN analyzer and the certified reference material (CRM) L-alanine. The CHN contents and their uncertainties, as measured using the single-point calibration method, were 40.36 ± 0.20% for C, 7.86 ± 0.13% for H, and 15.66 ± 0.09% for N; the results obtained using the bracket calibration method were also comparable. The method described in this study is reasonable, convenient, and meets the general requirement of having uncertainties ≤ 0.4%.

  16. Trinucleotide expansions leading to an extended poly-L-alanine segment in the poly (A) binding protein PABPN1 cause fibril formation.

    PubMed

    Scheuermann, Till; Schulz, Barbe; Blume, Alfred; Wahle, Elmar; Rudolph, Rainer; Schwarz, Elisabeth

    2003-12-01

    The nuclear poly(A) binding protein (PABPN1) stimulates poly(A) polymerase and controls the lengths of poly(A) tails during pre-mRNA processing. The wild-type protein possesses 10 consecutive Ala residues immediately after the start methionine. Trinucleotide expansions in the coding sequence result in an extension of the Ala stretch to maximal 17 Ala residues in total. Individuals carrying the trinucleotide expansions suffer from oculopharyngeal muscular dystrophy (OPMD). Intranuclear inclusions consisting predominantly of PABPN1 have been recognized as a pathological hallmark of the genetic disorder. To elucidate the molecular events that lead to disease, recombinant PABPN1, and N-terminal fragments of the protein with varying poly-L-alanine stretches were analyzed. As the full-length protein displayed a strong tendency to aggregate into amorphous deposits, soluble N-terminal fragments were also studied. Expansion of the poly-L-alanine sequence to the maximal length observed in OPMD patients led to an increase of alpha-helical structure. Upon prolonged incubation the protein was found in fibrils that showed all characteristics of amyloid-like fibers. The lag-phase of fibril formation could be reduced by seeding. Structural analysis of the fibrils indicated antiparallel beta-sheets.

  17. Identification of novel inhibitors against Mycobacterium tuberculosis L-alanine dehydrogenase (MTB-AlaDH) through structure-based virtual screening.

    PubMed

    Saxena, Shalini; Devi, Parthiban Brindha; Soni, Vijay; Yogeeswari, Perumal; Sriram, Dharmarajan

    2014-02-01

    Mycobacterium tuberculosis (MTB) the etiological agent of tuberculosis (TB) survives in the human host for decades evading the immune system in a latent or persistent state. The Rv2780 (ald) gene that codes for L-alanine dehydrogenase (L-AlaDH) enzyme catalyzes reversible oxidative deamination of L-alanine to pyruvate and is overexpressed under hypoxic and nutrient starvation conditions in MTB. At present, as there is no suitable drug available to treat dormant tuberculosis; it is essential to identify drug candidates that could potentially treat dormant TB. Availability of crystal structure of MTB L-AlaDH bound with co-factor NAD+ facilitated us to employ structure-based virtual screening approach to obtain new hits from a commercial library of Asinex database using energy-optimized pharmacophore modeling. The resulting pharmacophore consisted of three hydrogen bond donor sites (D) and two hydrogen bond acceptor sites (A). The database compounds with a fitness score more than 1.0 were further subjected to Glide high-throughput virtual screening and docking. Thus, we report the identification of best five hits based on structure-based design and their in vitro enzymatic inhibition studies revealed IC₅₀ values in the range of 35-80 μM.

  18. Kinetic Studies and Mechanism of Hydrogen Peroxide Catalytic Decomposition by Cu(II) Complexes with Polyelectrolytes Derived from L-Alanine and Glycylglycine

    PubMed Central

    Skounas, Spyridon; Methenitis, Constantinos; Pneumatikakis, George; Morcellet, Michel

    2010-01-01

    The catalytic decomposition of hydrogen peroxide by Cu(II) complexes with polymers bearing L-alanine (PAla) and glycylglycine (PGlygly) in their side chain was studied in alkaline aqueous media. The reactions were of pseudo-first order with respect to [H2O2] and [L-Cu(II)] (L stands for PAla or PGlygly) and the reaction rate was increased with pH increase. The energies of activation for the reactions were determined at pH 8.8, in a temperature range of 293–308 K. A suitable mechanism is proposed to account for the kinetic data, which involves the Cu(II)/Cu(I) redox pair, as has been demonstrated by ESR spectroscopy. The trend in catalytic efficiency is in the order PGlygly>PAla, due to differences in modes of complexation and in the conformation of the macromolecular ligands. PMID:20721280

  19. The metabolism of the non-proteinogenic amino acid β-N-methylamino-L-alanine (BMAA) in the cyanobacterium Synechocystis PCC6803.

    PubMed

    Downing, Simoné; Downing, Timothy Grant

    2016-06-01

    The neurotoxic amino acid β-N-methylamino-L-alanine (BMAA) is produced by cyanobacteria under nitrogen starvation conditions and its metabolism is closely associated with cellular nitrogen control. Very little is known regarding the metabolism or biosynthesis of this amino acid in the producing organisms and current knowledge is limited to the spontaneous formation of carbamate adducts in the presence of aqueous carbon dioxide, the rapid removal of free cellular BMAA upon the addition of ammonia to nitrogen-starved cyanobacterial cultures, and the link between cellular nitrogen status and BMAA synthesis. Data presented here show that exogenous BMAA is readily metabolised by cyanobacteria during which, the primary amino group is rapidly transferred to other cellular amino acids. Furthermore, data suggest that BMAA is metabolised in cyanobacteria via a reversible transamination reaction. This study presents novel data on BMAA metabolism in cyanobacteria and provides the first proposed biosynthetic precursor to BMAA biosynthesis in cyanobacteria.

  20. Cyanobacterial Blooms and the Occurrence of the neurotoxin beta-N-methylamino-L-alanine (BMAA) in South Florida Aquatic Food Webs

    PubMed Central

    Brand, Larry E.; Pablo, John; Compton, Angela; Hammerschlag, Neil; Mash, Deborah C.

    2010-01-01

    Recent studies demonstrate that most cyanobacteria produce the neurotoxin beta-N-methylamino-L-alanine (BMAA) and that it can biomagnify in at least one terrestrial food chain. BMAA has been implicated as a significant environmental risk in the development of neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, and Amyotrophic Lateral Sclerosis (ALS). We examined several blooms of cyanobacteria in South Florida, and the BMAA content of resident animals, including species used as human food. A wide range of BMAA concentrations were found, ranging from below assay detection limits to approximately 7000 μg/g, a concentration associated with a potential long-term human health hazard. PMID:21057660

  1. Kinetic Studies and Mechanism of Hydrogen Peroxide Catalytic Decomposition by Cu(II) Complexes with Polyelectrolytes Derived from L-Alanine and Glycylglycine.

    PubMed

    Skounas, Spyridon; Methenitis, Constantinos; Pneumatikakis, George; Morcellet, Michel

    2010-01-01

    The catalytic decomposition of hydrogen peroxide by Cu(II) complexes with polymers bearing L-alanine (PAla) and glycylglycine (PGlygly) in their side chain was studied in alkaline aqueous media. The reactions were of pseudo-first order with respect to [H(2)O(2)] and [L-Cu(II)] (L stands for PAla or PGlygly) and the reaction rate was increased with pH increase. The energies of activation for the reactions were determined at pH 8.8, in a temperature range of 293-308 K. A suitable mechanism is proposed to account for the kinetic data, which involves the Cu(II)/Cu(I) redox pair, as has been demonstrated by ESR spectroscopy. The trend in catalytic efficiency is in the order PGlygly>PAla, due to differences in modes of complexation and in the conformation of the macromolecular ligands.

  2. Studies on optical, mechanical and transport properties of NLO active L-alanine formate single crystal grown by modified Sankaranarayanan Ramasamy (SR) method

    NASA Astrophysics Data System (ADS)

    Justin Raj, C.; Dinakaran, S.; Krishnan, S.; Milton Boaz, B.; Robert, R.; Jerome Das, S.

    2008-04-01

    Bulk single crystals of L-alanine formate of 10 mm diameter and 50 mm length have been grown with an aid of modified Sankaranarayanan-Ramasamy (SR) uniaxial crystal growth method within a period of ten days. The optical properties of the grown crystal were calculated from UV transmission spectral analysis. The second harmonic generation efficiency of the grown crystal was confirmed by Kurtz powder test. In order to determine the mechanical strength of the crystal, Vicker's microhardness test was carried along the growth plane (0 0 1). Dielectric studies reveal that both dielectric constant and dielectric loss decreases with increase in frequency. Photoconductivity study confirms the negative photoconducting nature of the crystal.

  3. Enhancement in second harmonic generation efficiency, laser damage threshold and optical transparency of Mn 2+ doped L-alanine crystals: A correlation with crystalline perfection

    NASA Astrophysics Data System (ADS)

    Kushwaha, S. K.; Rathee, S. P.; Maurya, K. K.; Bhagavannarayana, G.

    2011-08-01

    Effect on crystalline perfection, second harmonic generation (SHG) efficiency, laser damage threshold (LDT) and optical transparency due to Mn 2+ doping in L-alanine crystals has been investigated. The crystalline perfection of pure and doped crystals was evaluated by high-resolution X-ray diffractometry, which revealed the improvement in the crystalline perfection at low and moderate doping concentrations. At moderate and high concentrations, the Mn 2+ ions were found to be incorporated predominantly at the interstitial sites of the crystalline matrix. The actual incorporated amount of dopants in the crystals was analyzed by atomic absorption spectroscopy. The optical transparency, SHG efficiency, and laser damage threshold of the grown crystals with different concentrations of Mn 2+ were investigated. From these studies it is revealed that Mn 2+ doping lead to a considerable enhancement in the measured nonlinear optical properties with a correlation on crystalline perfection.

  4. Chiral recognition in association between antimony potassium tartrate and bis(L-alaninate)ethylenediamine cobalt(III) complexes using electrospray ionization mass spectrometry

    PubMed

    Arakawa; Kobayashi; Ama

    2000-09-01

    The chiral recognition of metal complexes by a quick and sensitive mass spectrometric analysis was investigated. The principle is introduction of an external chiral standard compound and detection of the differential association with two optical isomers. Using electrospray ionization mass spectrometry we detected weak intermolecular association between the external chiral anion bis(mu-L-, D-tartrato)-diantimonate(III), [Sb2(L-, D-tart)2]2- and isomeric bis(L-alaninate) ethylenediamine cobalt(III) complex ions, [Co(L-ala)2(en)]+ in acetonitrile/water solution. The difference in the association with optical isomers of the Co complex was measured. The results were interpreted based on a model of intermolecular interaction involving hydrogen bonding. The prospects of the mass spectrometry method for chiral recognition using the external chiral negative ion [Sb2(L-, D-tart)2]2- was discussed.

  5. Enantioselective Collision-Activated Dissociation of Gas-Phase Tryptophan Induced by Chiral Recognition of Protonated uc(l)-Alanine Peptides

    NASA Astrophysics Data System (ADS)

    Fujihara, Akimasa; Matsuyama, Hiroki; Tajiri, Michiko; Wada, Yoshinao; Hayakawa, Shigeo

    2016-06-01

    Enantioselective dissociation in the gas phase is important for enantiomeric enrichment and chiral transmission processes in molecular clouds regarding the origin of homochirality in biomolecules. Enantioselective collision-activated dissociation (CAD) of tryptophan (Trp) and the chiral recognition ability of uc(l)-alanine peptides (uc(l)-Ala n ; n = 2-4) were examined using a linear ion trap mass spectrometer. CAD spectra of gas-phase heterochiral H+(uc(d)-Trp)(uc(l)-Ala n ) and homochiral H+(uc(l)-Trp)(uc(l)-Ala n ) noncovalent complexes were obtained as a function of the peptide size n. The H2O-elimination product was observed in CAD spectra of both heterochiral and homochiral complexes for n = 2 and 4, and in homochiral H+(uc(l)-Trp)(uc(l)-Ala3), indicating that the proton is attached to the uc(l)-alanine peptide, and H2O loss occurs from H+(uc(l)-Ala n ) in the noncovalent complexes. H2O loss did not occur in heterochiral H+(uc(d)-Trp)(uc(l)-Ala3), where NH3 loss and (H2O + CO) loss were the primary dissociation pathways. In heterochiral H+(uc(d)-Trp)(uc(l)-Ala3), the protonation site is the amino group of uc(d)-Trp, and NH3 loss and (H2O + CO) loss occur from H+(uc(d)-Trp). uc(l)-Ala peptides recognize uc(d)-Trp through protonation of the amino group for peptide size n = 3. NH3 loss and (H2O + CO) loss from H+(uc(d)-Trp) proceeds via enantioselective CAD in gas-phase heterochiral H+(uc(d)-Trp)(uc(l)-Ala3) at room temperature, whereas uc(l)-Trp dissociation was not observed in homochiral H+(uc(l)-Trp)(uc(l)-Ala3). These results suggest that enantioselective dissociation induced by chiral recognition of uc(l)-Ala peptides through protonation could play an important role in enantiomeric enrichment and chiral transmission processes of amino acids.

  6. A comparative study of MP2, B3LYP, RHF and SCC-DFTB force fields in predicting the vibrational spectra of N-acetyl-L-alanine-N'-methyl amide: VA and VCD spectra

    NASA Astrophysics Data System (ADS)

    Bohr, H. G.; Jalkanen, K. J.; Elstner, M.; Frimand, K.; Suhai, S.

    1999-07-01

    Recently we have looked for spectroscopic probes for secondary structural elements in the vibrational spectra of N-acetyl-L-alanine-N'-methyl amide (NALANMA), L-alanine (LA), N-acetyl-L-alanyl-L-alanine-N'-methyl amide (NALALANMA) and L-alanyl-L-alanine (LALA). Our goal has been to identify spectroscopic probes which can be used to identify specific secondary structural elements in peptides, polypeptides and proteins. In this work we present our comparative analysis of the MP2, B3LYP, RHF and SCC-DFTB quantum force fields to predict the vibrational absorption (VA) and vibrational circular dichroism (VCD) spectra of NALANMA. We have utilised MP2/6-31G*, B3LYP/6-31G*, RHF/6-31G* and SCC-DFTB level theory to determine the geometries and Hessians, atomic polar tensors (APT) and atomic axial tensors (AAT) which are required for simulating the VA and VCD spectra. We have also calculated the AAT at the RHF/6-31G** level and utilised the above force fields to document the difference between the RHF and B3LYP methodologies for the calculation of these tensors. The VA and VCD simulations are compared with the experimentally measured spectra for NALANMA.

  7. Structural and Biochemical Analyses of Mycobacterium tuberculosis N-Acetylmuramyl-l-alanine Amidase Rv3717 Point to a Role in Peptidoglycan Fragment Recycling*

    PubMed Central

    Prigozhin, Daniil M.; Mavrici, Daniela; Huizar, John P.; Vansell, Hilary J.; Alber, Tom

    2013-01-01

    Peptidoglycan hydrolases are key enzymes in bacterial cell wall homeostasis. Understanding the substrate specificity and biochemical activity of peptidoglycan hydrolases in Mycobacterium tuberculosis is of special interest as it can aid in the development of new cell wall targeting therapeutics. In this study, we report biochemical and structural characterization of the mycobacterial N-acetylmuramyl-l-alanine amidase, Rv3717. The crystal structure of Rv3717 in complex with a dipeptide product shows that, compared with previously characterized peptidoglycan amidases, the enzyme contains an extra disulfide-bonded β-hairpin adjacent to the active site. The structure of two intermediates in assembly reveal that Zn2+ binding rearranges active site residues, and disulfide formation promotes folding of the β-hairpin. Although Zn2+ is required for hydrolysis of muramyl dipeptide, disulfide oxidation is not required for activity on this substrate. The orientation of the product in the active site suggests a role for a conserved glutamate (Glu-200) in catalysis; mutation of this residue abolishes activity. The product binds at the head of a closed tunnel, and the enzyme showed no activity on polymerized peptidoglycan. These results point to a potential role for Rv3717 in peptidoglycan fragment recycling. PMID:24019530

  8. Structural and biochemical analyses of Mycobacterium tuberculosis N-acetylmuramyl-L-alanine amidase Rv3717 point to a role in peptidoglycan fragment recycling.

    PubMed

    Prigozhin, Daniil M; Mavrici, Daniela; Huizar, John P; Vansell, Hilary J; Alber, Tom

    2013-11-01

    Peptidoglycan hydrolases are key enzymes in bacterial cell wall homeostasis. Understanding the substrate specificity and biochemical activity of peptidoglycan hydrolases in Mycobacterium tuberculosis is of special interest as it can aid in the development of new cell wall targeting therapeutics. In this study, we report biochemical and structural characterization of the mycobacterial N-acetylmuramyl-L-alanine amidase, Rv3717. The crystal structure of Rv3717 in complex with a dipeptide product shows that, compared with previously characterized peptidoglycan amidases, the enzyme contains an extra disulfide-bonded β-hairpin adjacent to the active site. The structure of two intermediates in assembly reveal that Zn(2+) binding rearranges active site residues, and disulfide formation promotes folding of the β-hairpin. Although Zn(2+) is required for hydrolysis of muramyl dipeptide, disulfide oxidation is not required for activity on this substrate. The orientation of the product in the active site suggests a role for a conserved glutamate (Glu-200) in catalysis; mutation of this residue abolishes activity. The product binds at the head of a closed tunnel, and the enzyme showed no activity on polymerized peptidoglycan. These results point to a potential role for Rv3717 in peptidoglycan fragment recycling.

  9. Detection of cyanobacterial neurotoxin β-N-methylamino-l-alanine within shellfish in the diet of an ALS patient in Florida.

    PubMed

    Banack, Sandra Anne; Metcalf, James S; Bradley, Walter G; Cox, Paul Alan

    2014-11-01

    Cyanobacteria produce the neurotoxic amino acid β-N-methylamino-l-alanine (BMAA), which in contaminated marine waters has been found to accumulate in shellfish. Exposure to BMAA has been associated with an increased risk of neurodegenerative disease. Analysis of blinded samples found BMAA to be present in neuroproteins of individuals who died from ALS and ALS/PDC, but generally not in the brains of patients who died of causes unrelated to neurodegeneration or Huntington's disease, an autosomal dominant neurodegenerative disease. We here report support for a link between a patient with ALS and chronic exposure to the cyanobacterial neurotoxin BMAA via shellfish consumption. The patient had frequently eaten lobsters collected in Florida Bay for approximately 30 years. LC-MS/MS analysis of two lobsters which this ALS patient had placed in his freezer revealed BMAA at concentrations of 27 and 4 μg/g, respectively, as well as the presence of 2,4-diaminobutyric acid (DAB), a BMAA isomer. Two additional lobsters recently collected from Florida Bay also contained the neurotoxins BMAA and DAB. These data suggest that invertebrates collected in water where cyanobacterial blooms are present, if consumed, may result in direct human exposure to these neurotoxic amino acids. The data support the assertion that prolonged exposure to BMAA may have played a role in the etiology of ALS in this patient. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Distinguishing the cyanobacterial neurotoxin beta-N-methylamino-L-alanine (BMAA) from its structural isomer 2,4-diaminobutyric acid (2,4-DAB).

    PubMed

    Banack, S A; Downing, T G; Spácil, Z; Purdie, E L; Metcalf, J S; Downing, S; Esterhuizen, M; Codd, G A; Cox, P A

    2010-11-01

    The cyanobacterial neurotoxin beta-N-methylamino-L-alanine (BMAA) has been associated with certain forms of progressive neurodegenerative disease, including sporadic Amyotrophic Lateral Sclerosis and Alzheimer's disease. Reports of BMAA in cyanobacterial blooms from lakes, reservoirs, and other water resources continue to be made by investigators in a variety of laboratories. Recently it was suggested that during analysis BMAA may be confused with its structural isomer 2,4-diaminobutyric acid (2,4-DAB), or that current detection methods may mistake other compounds for BMAA. We here review the evidence that BMAA can be consistently and reliably separated from 2,4-DAB during reversed-phase HPLC, and that BMAA can be confidently distinguished from 2,4-DAB during triple quadrupole LC-MS/MS analysis by i) different retention times, ii) diagnostic product ions resulting from collision-induced dissociation, and iii) consistent ratios between selected reaction monitoring (SRM) transitions. Furthermore, underivatized BMAA can be separated from 2,4-DAB with an amino acid analyzer with post-column visualization using ninhydrin. Other compounds that may be theoretically confused with BMAA during chloroformate derivatization during GC analysis are distinguished due to their different retention times.

  11. Reversed-phase HPLC/FD method for the quantitative analysis of the neurotoxin BMAA (β-N-methylamino-L-alanine) in cyanobacteria.

    PubMed

    Cianca, R C Cervantes; Baptista, M S; Silva, Luís Pinto da; Lopes, V R; Vasconcelos, V M

    2012-03-01

    A method has been developed and optimized in order to detect and quantify the non-protein amino acid β-N-methylamino-L-alanine(BMAA) in cyanobacteria. The novelty of the method is that we have used methanol instead of acetonitrile as the eluent. The method includes extraction with 0.1 M trichloroacetic acid (free BMAA) or protein hydrolysis with 6 M hydrochloric acid (total BMAA), derivatization with AQC (6-aminoquinolyl-N-hydroxysuccinimidyl carbamate) and reversed-phase high-performance liquid chromatography analysis with fluorescence detection (HPLC/FD). Detection limits ranged from 0.35 to 0.75 pg injected, while quantification limits ranged from 1.10 to 2.55 pg injected for total and free BMAA hydrolysis, respectively. The linear response range was up to 850 pmol in both methods, embracing three orders of magnitude. The method was successfully applied to a lyophilized estuarine species of Nostoc (LEGE 06077). All previous published methods for BMAA quantification, using HPLC/FD, have reported the usage of acetonitrile. This is the first report using methanol as the mobile phase. Although the elution strength differs with both solvents, the final method proved efficient for the quantification of BMAA in this complex sample. The method resulted effective, low-priced, and simple, being suitable for routine monitoring of BMAA in cyanobacteria.

  12. Transfer of developmental neurotoxin β-N-methylamino-l-alanine (BMAA) via milk to nursed offspring: Studies by mass spectrometry and image analysis.

    PubMed

    Andersson, Marie; Karlsson, Oskar; Banack, Sandra Anne; Brandt, Ingvar

    2016-09-06

    The cyanobacterial non-proteinogenic amino acid β-N-methylamino-l-alanine (BMAA) is proposed to be involved in the etiology of amyotrophic lateral sclerosis/parkinsonism dementia complex. When administered as single doses to neonatal rats, BMAA gives rise to cognitive and neurodegenerative impairments in the adult animal. Here, we employed mass spectrometry (LC-MS/MS) and autoradiographic imaging to examine the mother-to-pup transfer of BMAA in rats. The results show that unchanged BMAA was secreted into the milk and distributed to the suckling pups. The concentration of BMAA in pup stomach milk and the neonatal liver peaked after 8h, while the concentration in the pup brain increased throughout the study period. About 1 and 6% of the BMAA recovered from adult liver and brain were released following hydrolysis, suggesting that this fraction was associated with protein. No association to milk protein was observed. Injection of rat pups with [methyl-(14)C]-l-BMAA or [carboxyl-(14)C]-l-BMAA resulted in highly similar distribution patterns, indicating no or low metabolic elimination of the methylamino- or carboxyl groups. In conclusion, BMAA is transported as a free amino acid to rat milk and suckling pups. The results strengthen the proposal that mothers' milk could be a source of exposure for BMAA in human infants.

  13. Environmental neurotoxin interaction with proteins: Dose-dependent increase of free and protein-associated BMAA (β-N-methylamino-L-alanine) in neonatal rat brain.

    PubMed

    Karlsson, Oskar; Jiang, Liying; Ersson, Lisa; Malmström, Tim; Ilag, Leopold L; Brittebo, Eva B

    2015-10-26

    β-Methylamino-L-alanine (BMAA) is implicated in the aetiology of neurodegenerative disorders. Neonatal exposure to BMAA induces cognitive impairments and progressive neurodegenerative changes including intracellular fibril formation in the hippocampus of adult rats. It is unclear why the neonatal hippocampus is especially vulnerable and the critical cellular perturbations preceding BMAA-induced toxicity remains to be elucidated. The aim of this study was to compare the level of free and protein-associated BMAA in neonatal rat brain and peripheral tissues after different exposures to BMAA. Ultra-high performance liquid chromatography-tandem mass spectrometry analysis revealed that BMAA passed the neonatal blood-brain barrier and was distributed to all studied brain areas. BMAA was also associated to proteins in the brain, especially in the hippocampus. The level in the brain was, however, considerably lower compared to the liver that is not a target organ for BMAA. In contrast to the liver there was a significantly increased level of protein-association of BMAA in the hippocampus and other brain areas following repeated administration suggesting that the degradation of BMAA-associated proteins may be lower in neonatal brain than in the liver. Additional evidence is needed in support of a role for protein misincorporation in the neonatal hippocampus for long-term effects of BMAA.

  14. Environmental neurotoxin interaction with proteins: Dose-dependent increase of free and protein-associated BMAA (β-N-methylamino-L-alanine) in neonatal rat brain

    PubMed Central

    Karlsson, Oskar; Jiang, Liying; Ersson, Lisa; Malmström, Tim; Ilag, Leopold L.; Brittebo, Eva B.

    2015-01-01

    β-Methylamino-L-alanine (BMAA) is implicated in the aetiology of neurodegenerative disorders. Neonatal exposure to BMAA induces cognitive impairments and progressive neurodegenerative changes including intracellular fibril formation in the hippocampus of adult rats. It is unclear why the neonatal hippocampus is especially vulnerable and the critical cellular perturbations preceding BMAA-induced toxicity remains to be elucidated. The aim of this study was to compare the level of free and protein-associated BMAA in neonatal rat brain and peripheral tissues after different exposures to BMAA. Ultra-high performance liquid chromatography-tandem mass spectrometry analysis revealed that BMAA passed the neonatal blood-brain barrier and was distributed to all studied brain areas. BMAA was also associated to proteins in the brain, especially in the hippocampus. The level in the brain was, however, considerably lower compared to the liver that is not a target organ for BMAA. In contrast to the liver there was a significantly increased level of protein-association of BMAA in the hippocampus and other brain areas following repeated administration suggesting that the degradation of BMAA-associated proteins may be lower in neonatal brain than in the liver. Additional evidence is needed in support of a role for protein misincorporation in the neonatal hippocampus for long-term effects of BMAA. PMID:26498001

  15. Determination of the neurotoxin BMAA (beta-N-methylamino-L-alanine) in cycad seed and cyanobacteria by LC-MS/MS (liquid chromatography tandem mass spectrometry).

    PubMed

    Rosén, Johan; Hellenäs, Karl-Erik

    2008-12-01

    A highly specific method for the analysis of beta-N-methylamino-L-alanine (BMAA) by LC-MS/MS (liquid chromatography tandem mass spectrometry) has been developed and applied for cycad seeds and cyanobacteria. BMAA was analysed as a free fraction or as total BMAA after acidic hydrolysis to release any protein-bound BMAA. Deuterium labelled BMAA was synthesised and used as internal standard. The method comprises HILIC (hydrophilic interaction chromatography) and positive electrospray ionisation of the native compound, i.e. no derivatisation was used. For safe identification five specific product ions (m/z 102, 88, 76, 73 and 44), all derived from a precursor ion of m/z 119 and originating from different parts of the molecule, were detected (typical relative abundance 100%, 16%, 14%, 12% and 22% respectively). Cyanobacteria or muscle tissue was spiked with BMAA (10 to 1000 microg g(-1)) to validate the method (accuracy 95% to 109%, relative standard deviation 1% to 6%). The detection limit for free and total BMAA in tissue was <1 microg g(-1) and <4 microg g(-1) respectively. BMAA was successfully identified and quantified in cycad seeds, whereas previously reported findings of BMAA in samples of cyanobacteria could not be confirmed. Instead, the presence of alpha-,gamma-diamino butyric acid (DAB), an isomer of BMAA, was confirmed in one sample. The possible implications of this finding are discussed.

  16. Early hippocampal cell death, and late learning and memory deficits in rats exposed to the environmental toxin BMAA (β-N-methylamino-L-alanine) during the neonatal period.

    PubMed

    Karlsson, Oskar; Roman, Erika; Berg, Anna-Lena; Brittebo, Eva B

    2011-06-01

    We have reported previously that exposure to the cyanobacterial neurotoxin β-N-methylamino-L-alanine (BMAA) during the neonatal period causes cognitive impairments in adult rats. The aim of this study was to investigate the long-term effects of neonatal BMAA exposure on learning and memory mechanisms and to identify early morphological changes in the neonatal brain. BMAA was injected subcutaneously in rat pups on postnatal days 9-10. BMAA (50 and 200 mg/kg) caused distinct deficits in spatial learning and memory in adult animals but no morphological changes. No impairment of recognition memory was detected, suggesting that neonatal exposure to BMAA preferentially affects neuronal systems that are important for spatial tasks. Histopathological examination revealed early neuronal cell death as determined by TUNEL staining in the hippocampus 24 h after a high dose (600 mg/kg) of BMAA whereas no changes were observed at lower doses (50 and 200 mg/kg). In addition, there was a low degree of neuronal cell death in the retrosplenial and cingulate cortices, areas that are also important for cognitive function. Taken together, these results indicate that BMAA is a developmental neurotoxin inducing long-term changes in cognitive function. The risk posed by BMAA as a potential human neurotoxin merits further consideration, particularly if the proposed biomagnifications in the food chain are confirmed.

  17. Detection of Cyanotoxins, β-N-methylamino-l-alanine and Microcystins, from a Lake Surrounded by Cases of Amyotrophic Lateral Sclerosis

    PubMed Central

    Banack, Sandra Anne; Caller, Tracie; Henegan, Patricia; Haney, James; Murby, Amanda; Metcalf, James S.; Powell, James; Cox, Paul Alan; Stommel, Elijah

    2015-01-01

    A cluster of amyotrophic lateral sclerosis (ALS) has been previously described to border Lake Mascoma in Enfield, NH, with an incidence of ALS approximating 25 times expected. We hypothesize a possible association with cyanobacterial blooms that can produce β-N-methylamino-l-alanine (BMAA), a neurotoxic amino acid implicated as a possible cause of ALS/PDC in Guam. Muscle, liver, and brain tissue samples from a Lake Mascoma carp, as well as filtered aerosol samples, were analyzed for microcystins (MC), free and protein-bound BMAA, and the BMAA isomers 2,4-diaminobutyric acid (DAB) and N-(2-aminoethyl)glycine (AEG). In carp brain, BMAA and DAB concentrations were 0.043 μg/g ± 0.02 SD and 0.01 μg/g ± 0.002 SD respectively. In carp liver and muscle, the BMAA concentrations were 1.28 μg/g and 1.27 μg/g respectively, and DAB was not detected. BMAA was detected in the air filters, as were the isomers DAB and AEG. These results demonstrate that a putative cause for ALS, BMAA, exists in an environment that has a documented cluster of ALS. Although cause and effect have not been demonstrated, our observations and measurements strengthen the association. PMID:25643180

  18. β-N-methylamino-l-alanine (BMAA) and isomers: Distribution in different food web compartments of Thau lagoon, French Mediterranean Sea.

    PubMed

    Réveillon, Damien; Abadie, Eric; Séchet, Véronique; Masseret, Estelle; Hess, Philipp; Amzil, Zouher

    2015-09-01

    The neurotoxin BMAA (β-N-methylamino-l-alanine) and its isomer DAB (2,4-diaminobutyric acid) have been detected in seafood worldwide, including in Thau lagoon (French Mediterranean Sea). A cluster of amyotrophic lateral sclerosis (ALS), a neurodegenerative disease associated with BMAA, has also been observed in this region. Mussels, periphyton (i.e. biofilms attached to mussels) and plankton were sampled between July 2013 and October 2014, and analyzed using HILIC-MS/MS. BMAA, DAB and AEG (N-(2-aminoethyl)glycine) were found in almost all the samples of the lagoon. BMAA and DAB were present at 0.58 and 0.83, 2.6 and 3.3, 4.0 and 7.2 μg g(-1) dry weight in plankton collected with nets, periphyton and mussels, respectively. Synechococcus sp., Ostreococcus tauri, Alexandrium catenella and eight species of diatoms were cultured and screened for BMAA and analogs. While Synechococcus sp., O. tauri and A. catenella did not produce BMAA under our culture conditions, four diatoms species contained both BMAA and DAB. Hence, diatoms may be a source of BMAA for mussels. Unlike other toxins produced by microalgae, BMAA and DAB were detected in significant amounts in tissues other than digestive glands in mussels.

  19. β-N-Methylamino-L-alanine (BMAA) perturbs alanine, aspartate and glutamate metabolism pathways in human neuroblastoma cells as determined by metabolic profiling.

    PubMed

    Engskog, Mikael K R; Ersson, Lisa; Haglöf, Jakob; Arvidsson, Torbjörn; Pettersson, Curt; Brittebo, Eva

    2017-02-04

    β-Methylamino-L-alanine (BMAA) is a non-proteinogenic amino acid that induces long-term cognitive deficits, as well as an increased neurodegeneration and intracellular fibril formation in the hippocampus of adult rodents following short-time neonatal exposure and in vervet monkey brain following long-term exposure. It has also been proposed to be involved in the etiology of neurodegenerative disease in humans. The aim of this study was to identify metabolic effects not related to excitotoxicity or oxidative stress in human neuroblastoma SH-SY5Y cells. The effects of BMAA (50, 250, 1000 µM) for 24 h on cells differentiated with retinoic acid were studied. Samples were analyzed using LC-MS and NMR spectroscopy to detect altered intracellular polar metabolites. The analysis performed, followed by multivariate pattern recognition techniques, revealed significant perturbations in protein biosynthesis, amino acid metabolism pathways and citrate cycle. Of specific interest were the BMAA-induced alterations in alanine, aspartate and glutamate metabolism and as well as alterations in various neurotransmitters/neuromodulators such as GABA and taurine. The results indicate that BMAA can interfere with metabolic pathways involved in neurotransmission in human neuroblastoma cells.

  20. Beta-N-methylamino-l-alanine: LC-MS/MS Optimization, Screening of Cyanobacterial Strains and Occurrence in Shellfish from Thau, a French Mediterranean Lagoon

    PubMed Central

    Réveillon, Damien; Abadie, Eric; Séchet, Véronique; Brient, Luc; Savar, Véronique; Bardouil, Michèle; Hess, Philipp; Amzil, Zouher

    2014-01-01

    β-N-methylamino-l-alanine (BMAA) is a neurotoxic non-protein amino acid suggested to be involved in neurodegenerative diseases. It was reported to be produced by cyanobacteria, but also found in edible aquatic organisms, thus raising concern of a widespread human exposure. However, the chemical analysis of BMAA and its isomers are controversial, mainly due to the lack of selectivity of the analytical methods. Using factorial design, we have optimized the chromatographic separation of underivatized analogues by a hydrophilic interaction chromatography coupled to tandem mass spectrometry (HILIC-MS/MS) method. A combination of an effective solid phase extraction (SPE) clean-up, appropriate chromatographic resolution and the use of specific mass spectral transitions allowed for the development of a highly selective and sensitive analytical procedure to identify and quantify BMAA and its isomers (in both free and total form) in cyanobacteria and mollusk matrices (LOQ of 0.225 and 0.15 µg/g dry weight, respectively). Ten species of cyanobacteria (six are reported to be BMAA producers) were screened with this method, and neither free nor bound BMAA could be found, while both free and bound DAB were present in almost all samples. Mussels and oysters collected in 2009 in the Thau Lagoon, France, were also screened, and bound BMAA and its two isomers, DAB and AEG, were observed in all samples (from 0.6 to 14.4 µg/g DW), while only several samples contained quantifiable free BMAA. PMID:25405857

  1. Protein association of the neurotoxin and non-protein amino acid BMAA (β-N-methylamino-L-alanine) in the liver and brain following neonatal administration in rats.

    PubMed

    Karlsson, Oskar; Jiang, Liying; Andersson, Marie; Ilag, Leopold L; Brittebo, Eva B

    2014-04-07

    The environmental neurotoxin β-N-methylamino-L-alanine (BMAA) is not an amino acid that is normally found in proteins. Our previous autoradiographic study of (3)H-labeled BMAA in adult mice unexpectedly revealed a tissue distribution similar to that of protein amino acids. The aim of this study was to characterize the distribution of free and protein-bound BMAA in neonatal rat tissues following a short exposure using autoradiographic imaging and ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The autoradiographic imaging of (14)C-L-BMAA demonstrated a distinct uptake of radioactivity that was retained following acid extraction in tissues with a high rate of cell turnover and/or protein synthesis. The UHPLC-MS/MS analysis conclusively demonstrated a dose-dependent increase of protein-associated BMAA in neonatal rat tissues. The level of protein-associated BMAA in the liver was more than 10 times higher than that in brain regions not fully protected by the blood-brain barrier which may be due to the higher rate of protein synthesis in the liver. In conclusion, this study demonstrated that BMAA was associated with rat proteins suggesting that BMAA may be misincorporated into proteins. However, protein-associated BMAA seemed to be cleared over time, as none of the samples from adult rats had any detectable free or protein-associated BMAA.

  2. Beta-N-methylamino-L-alanine: LC-MS/MS optimization, screening of cyanobacterial strains and occurrence in shellfish from Thau, a French Mediterranean lagoon.

    PubMed

    Réveillon, Damien; Abadie, Eric; Séchet, Véronique; Brient, Luc; Savar, Véronique; Bardouil, Michèle; Hess, Philipp; Amzil, Zouher

    2014-11-17

    β-N-methylamino-L-alanine (BMAA) is a neurotoxic non-protein amino acid suggested to be involved in neurodegenerative diseases. It was reported to be produced by cyanobacteria, but also found in edible aquatic organisms, thus raising concern of a widespread human exposure. However, the chemical analysis of BMAA and its isomers are controversial, mainly due to the lack of selectivity of the analytical methods. Using factorial design, we have optimized the chromatographic separation of underivatized analogues by a hydrophilic interaction chromatography coupled to tandem mass spectrometry (HILIC-MS/MS) method. A combination of an effective solid phase extraction (SPE) clean-up, appropriate chromatographic resolution and the use of specific mass spectral transitions allowed for the development of a highly selective and sensitive analytical procedure to identify and quantify BMAA and its isomers (in both free and total form) in cyanobacteria and mollusk matrices (LOQ of 0.225 and 0.15 µg/g dry weight, respectively). Ten species of cyanobacteria (six are reported to be BMAA producers) were screened with this method, and neither free nor bound BMAA could be found, while both free and bound DAB were present in almost all samples. Mussels and oysters collected in 2009 in the Thau Lagoon, France, were also screened, and bound BMAA and its two isomers, DAB and AEG, were observed in all samples (from 0.6 to 14.4 µg/g DW), while only several samples contained quantifiable free BMAA.

  3. Pore Diameter Dependence and Segmental Dynamics of Poly-Z-L-lysine and Poly-L-alanine Confined in 1D Nanocylindrical Geometry

    NASA Astrophysics Data System (ADS)

    Tuncel, Eylul; Suzuki, Yasuhito; Iossifidis, Agathaggelos; Steinhart, Martin; Butt, Hans-Jurgen; Floudas, George; Duran, Hatice

    Structure formation, thermodynamic stability, phase and dynamic behaviors of polypeptides are strongly affected by confinement. Since understanding the changes in these behaviors will allow their rational design as functional devices with tunable properties, herein we investigated Poly-Z-L-lysine (PZLL) and Poly-L-alanine (PAla) homopolypeptides confined in nanoporous alumina containing aligned cylindrical nanopores as a function of pore size by differential scanning calorimetry (DSC), Fourier Transform Infrared Spectroscopy, Solid-state NMR, X-ray diffraction, Dielectric spectroscopy(DS). Bulk PZLL exhibits a glass transition temperature (Tg) at about 301K while PZLL nanorods showed slightly lower Tg (294K). The dynamic investigation by DS also revealed a decrease (4K) in Tg between bulk and PZLL nanorods. DS is a very sensitive probe of the local and global secondary structure relaxation through the large dipole to study effect of confinement. The results revealed that the local segmental dynamics, associated with broken hydrogen bonds, and segmental dynamics speed-up on confinement.

  4. Characterization of a meso-chiral isomer of a hexanuclear Cu(II) cage from racemization of the L-alanine Schiff base.

    PubMed

    Rajesh, Chinnaiyan Mahalingam; Ray, Manabendra

    2014-09-14

    We are reporting structural characterization of two new hexanuclear cages (H3O)2[Cu3(μ3-OH)(μ3-NH3)(0.5)(L)3]2·8H2O (1) and (H3O)2[Cu3(μ3-OH)(μ3-H2O)(0.5)(L)3]2·8H2O (1a) where L(2-) is the dianionic form of the Schiff base of L-alanine and salicylaldehyde. The complex 1 has two C3 symmetric hydroxo bridged trinuclear halves joined by an ammonia or water molecule at the center through H-bonding. Each of the trinuclear halves is enantiopure but of opposite chirality to the other half, making the hexanuclear unit a meso isomer. Temperature dependent magnetic measurements showed the presence of ferromagnetic interactions among trinuclear Cu(II) units, a rare occurrence among trinuclear Cu(II) complexes. Characterization of the LiHL showed it to be enantiopure. Addition of a base, monitored using optical rotation, showed that racemization occurs as a result of base addition. The racemization depends on the base as well as the temperature. Base or Cu(II) induced racemization of amino acid derivatives has been indicated in a number of cases in the past but structural characterization of the products or formation of this type of chiral hexanuclear architecture was never reported. Structures of the complex and the ligand have a number of interesting H-bonding situations.

  5. Nepenthes insignis uses a C2-portion of the carbon skeleton of L-alanine acquired via its carnivorous organs, to build up the allelochemical plumbagin.

    PubMed

    Rischer, Heiko; Hamm, Andreas; Bringmann, Gerhard

    2002-03-01

    Tropical pitcher plants (Nepenthes) catch animals in their specialized cup-shaped leaves, digest the prey by secreting enzymes, and actively take up the resulting compounds. The benefit of this behaviour is the ability to grow and compete in nutrient-poor habitats. Our present in vitro study shows that not only the nitrogen of alanine fed to the carnivorous organs is used by the plant but that in addition intact C2-units derived from C-2 and C-3 of stable isotope labelled L-alanine serve as building blocks, here exemplarily for the synthesis of the secondary metabolite plumbagin, a potent allelochemical. This result adds a new facet to the benefit of carnivory for plants. The availability of plumbagin by a de novo synthesis probably enhances the plants' fitness in their defence against phytophagous and pathogenic organisms. A missing specific uptake or CoA activation mechanism might be the reason that acetate fed to the pitchers was not incorporated into the naphthoquinone plumbagin. The dihydronaphthoquinone glucosides rossoliside and plumbaside A, here isolated for the first time from Nepenthes, by contrast, showed no incorporation after feeding of any of the two precursors, suggesting these compounds to be storage forms with probably very low turnover rates.

  6. Physical gelation of binary mixtures of hydrocarbons mediated by n-lauroyl-L-alanine and characterization of their thermal and mechanical properties.

    PubMed

    Bhattacharya, Santanu; Pal, Asish

    2008-04-24

    Fatty acid amides, such as n-lauroyl-L-alanine, gelate both aliphatic and aromatic hydrocarbon solvents efficiently. In addition this compound is found to gelate the binary solvent mixtures comprised of aromatic hydrocarbon, e.g., toluene and aliphatic hydrocarbons, e.g., n-heptane. Scanning electron microscopy and atomic force microscopy show that the fiber thickness of the gel assembly increases progressively in the binary mixture of n-heptane and toluene with increasing percentage of toluene. The self-assembly patterns of the gels in individual solvents, n-heptane and toluene, are however different. The toluene gel consists of predominantly one type of morphological species, while n-heptane gel has more than one species leading to the polymorphic nature of the gel. The n-heptane gel is thermally more stable than the toluene gel as evident from the measurement using differential scanning calorimetry. The thermal stability of the gels prepared in the binary mixture of n-heptane and toluene is dependent on the composition of solvent mixture. Rheology of the gels shows that they are shear-thinning material and show characteristic behavior of soft viscoelastic solid. For the gels prepared from binary solvent mixture of toluene and n-heptane, with incorporation of more toluene in the binary mixture, the gel becomes a more viscoelastic solid. The time sweep rheology experiment demonstrates that the gel made in n-heptane has faster gel formation kinetics than that prepared in toluene.

  7. Structural, vibrational spectroscopic studies and quantum chemical calculations of n-(2,4-dinitrophenyl)-L-alanine methyl ester by density functional theory

    NASA Astrophysics Data System (ADS)

    Govindarasu, K.; Kavitha, E.

    2015-05-01

    In this paper, the vibrational wavenumbers of N-(2,4-dinitrophenyl)-L-alanine methyl ester (abbreviated as Dnp-ala-ome) were obtained from ab initio studies based on the density functional theory approach with B3LYP and M06-2X/6-31G(d,p) level of theories. The optimized geometry and structural features of the most potential nonlinear optical crystal Dnp-ala-ome and the vibrational spectral investigations have been thoroughly described with the FT-Raman and FT-IR spectra supported by the DFT computations. FT-IR (4000-400 cm-1) and FT-Raman spectra (3500-50 cm-1) in the solid phase and the UV-Vis spectra that dissolved in ethanol were recorded in the range of 200-800 nm. The Natural population analysis and natural bond orbital (NBO) analysis have also been carried out to analyze the effects of intramolecular charge transfer, intramolecular and hyperconjugative interactions on the geometries. The effects of frontier orbitals, HOMO and LUMO, transition of electron density transfer have also been discussed. The first order hyperpolarizability (β0) and related properties (β, α0 and Δα) of Dnp-ala-ome were calculated. In addition, molecular electrostatic potential (MEP) was investigated using theoretical calculations. The chemical reactivity and thermodynamic properties (heat capacity, entropy and enthalpy) of at different temperature are calculated.

  8. 3D culture of tonsil-derived mesenchymal stem cells in poly(ethylene glycol)-poly(L-alanine-co-L-phenyl alanine) thermogel.

    PubMed

    Park, Min Hee; Yu, Yeonsil; Moon, Hyo Jung; Ko, Du Young; Kim, Han Su; Lee, Hyukjin; Ryu, Kyung Ha; Jeong, Byeongmoon

    2014-11-01

    Poly(ethylene glycol)-poly(L-alanine-co-L-phenyl alanine) (PEG-PAF) aqueous solutions undergo sol-to-gel transition as the temperature increases. The transition is driven by the micelle aggregation involving the partial dehydration of the PEG block and the partial increase in β-sheet content of the PAF block. Tonsil-tissue-derived mesenchymal stem cells (TMSCs), a new stem cell resource, are encapsulated through the sol-to-gel transition of the TMSC-suspended PEG-PAF aqueous solutions. The encapsulated TMSCs are in vitro 3D cultured by using induction media supplemented with adipogenic, osteogenic, or chondrogenic factors, where the TMSCs preferentially undergo chondrogenesis with high expressions of type II collagen and sulfated glycosaminoglycan. As a feasibility study of the PEG-PAF thermogel for injectable tissue engineering, the TMSCs encapsulated in hydrogels are implanted in the subcutaneous layer of mice by injecting the TMSC suspended PEG-PAF aqueous solution. The in vivo studies also prove that TMSCs undergo chondrogenesis with high expression of the chondrogenic biomarkers. This study suggests that the TMSCs can be an excellent resource of MSCs, and the thermogelling PEG-PAF is a promising injectable tissue engineering scaffold, particularly for chondrogenic differentiation of the stem cells. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Analysis of β-N-methylamino-L-alanine (BMAA) in spirulina-containing supplements by liquid chromatography-tandem mass spectrometry

    PubMed Central

    2014-01-01

    Over the last decade the amino acid beta-N-methylamino-L-alanine (BMAA) has come under intense scrutiny. International laboratory and epidemiological research continues to support the hypothesis that environmental exposure to BMAA (e.g., through dietary practices, water supply) can promote the risk of various neurodegenerative diseases. A wide variety of cyanobacteria spp. have previously been reported to produce BMAA, with production levels dependent upon species, strain and environmental conditions. Since spirulina (Arthrospira spp.) is a member of the cyanobacteria phylum frequently consumed via dietary supplements, the presence of BMAA in such products may have public health implications. In the current work, we have analyzed ten spirulina-containing samples for the presence of BMAA; six pure spirulina samples from two separate raw materials suppliers, and four commercially-available multi-ingredient products containing 1.45 g of spirulina per 8.5 g serving. Because of controversy surrounding the measurement of BMAA, we have used two complementary liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods: one based on reversed phase LC (RPLC) with derivatization and the other based on hydrophilic interaction LC (HILIC). Potential matrix effects were corrected for by internal standardization using a stable isotope labeled BMAA standard. BMAA was not detected at low limits of detection (80 ng/g dry weight) in any of these product samples. Although these results are reassuring, BMAA analyses should be conducted on a wider sample selection and, perhaps, as part of ongoing spirulina production quality control testing and specifications. PMID:25120905

  10. Near-IR laser generation of a high-energy conformer of L-alanine and the mechanism of its decay in a low-temperature nitrogen matrix.

    PubMed

    Nunes, Cláudio M; Lapinski, Leszek; Fausto, Rui; Reva, Igor

    2013-03-28

    Monomers of L-alanine (ALA) were isolated in cryogenic nitrogen matrices at 14 K. Two conformers were identified for the compound trapped from the gas-phase into the solid nitrogen environment. The potential energy surface (PES) of ALA was theoretically calculated at the MP2 and QCISD levels. Twelve minima were located on this PES. Seven low-energy conformers fall within the 0-10 kJ mol(-1) range and should be appreciably populated in the equilibrium gas phase prior to deposition. Observation of only two forms in the matrices is explained in terms of calculated barriers to conformational rearrangements. All conformers with the O=C-O-H moiety in the cis orientation are separated by low barriers and collapse to the most stable form I during deposition of the matrix onto the low-temperature substrate. The second observed form II has the O=C-O-H group in the trans orientation. The remaining trans forms have very high relative energies (between 24 and 30 kJ mol(-1)) and are not populated. The high-energy trans form VI, that differs from I only by rotation of the OH group, was found to be separated from other conformers by barriers that are high enough to open a perspective for its stabilization in a matrix. The form VI was photoproduced in situ by narrow-band near-infrared irradiation of the samples at 6935-6910 cm(-1), where the first overtone of the OH stretching vibration in form I appears. The photogenerated form VI decays in N2 matrices back to conformer I with a characteristic decay time of ∼15 min. The mechanism of the VI → I relaxation is rationalized in terms of the proton tunneling.

  11. Analysis of β-N-methylamino-L-alanine (BMAA) in spirulina-containing supplements by liquid chromatography-tandem mass spectrometry.

    PubMed

    McCarron, Pearse; Logan, Alan C; Giddings, Sabrina D; Quilliam, Michael A

    2014-01-01

    Over the last decade the amino acid beta-N-methylamino-L-alanine (BMAA) has come under intense scrutiny. International laboratory and epidemiological research continues to support the hypothesis that environmental exposure to BMAA (e.g., through dietary practices, water supply) can promote the risk of various neurodegenerative diseases. A wide variety of cyanobacteria spp. have previously been reported to produce BMAA, with production levels dependent upon species, strain and environmental conditions. Since spirulina (Arthrospira spp.) is a member of the cyanobacteria phylum frequently consumed via dietary supplements, the presence of BMAA in such products may have public health implications. In the current work, we have analyzed ten spirulina-containing samples for the presence of BMAA; six pure spirulina samples from two separate raw materials suppliers, and four commercially-available multi-ingredient products containing 1.45 g of spirulina per 8.5 g serving. Because of controversy surrounding the measurement of BMAA, we have used two complementary liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods: one based on reversed phase LC (RPLC) with derivatization and the other based on hydrophilic interaction LC (HILIC). Potential matrix effects were corrected for by internal standardization using a stable isotope labeled BMAA standard. BMAA was not detected at low limits of detection (80 ng/g dry weight) in any of these product samples. Although these results are reassuring, BMAA analyses should be conducted on a wider sample selection and, perhaps, as part of ongoing spirulina production quality control testing and specifications.

  12. Selective brain uptake and behavioral effects of the cyanobacterial toxin BMAA (beta-N-methylamino-L-alanine) following neonatal administration to rodents.

    PubMed

    Karlsson, Oskar; Lindquist, Nils Gunnar; Brittebo, Eva B; Roman, Erika

    2009-06-01

    Cyanobacteria are extensively distributed in terrestrial and aquatic environments all over the world. Most cyanobacteria can produce the neurotoxin beta-N-methylamino-L-alanine (BMAA), which has been detected in several water systems and could accumulate in food chains. The aim of the study was to investigate the transfer of BMAA to fetal and neonatal brains and the effects of BMAA on the development of behavioral characteristics during the brain growth spurt (BGS) in rodents. Pregnant and neonatal mice were given an injection of (3)H-BMAA on gestational day 14 and postnatal day (PND) 10, respectively, and processed for tape-section autoradiography. The study revealed transplacental transfer of (3)H-BMAA and a significant uptake in fetal mouse brain. The radioactivity was specifically located in the hippocampus, striatum, brainstem, spinal cord and cerebellum of 10-day-old mice. The effect of repeated BMAA treatment (200 or 600 mg/kg s.c.) during BGS on rat behavior was also studied. BMAA treatment on PND 9-10 induced acute alterations, such as impaired locomotor ability and hyperactivity, in the behavior of neonatal rats. Furthermore, rats given the high dose of BMAA failed to habituate to the test environment when tested at juvenile age. In conclusion, the results demonstrated that BMAA was transferred to the neonatal brain and induced significant changes in the behavior of neonatal rats following administration during BGS. The observed behavioral changes suggest possible cognitive impairment. Increased information on the long-term effects of BMAA on cognitive function following fetal and neonatal exposure is required for assessment of the risk to children's health.

  13. Systematic detection of BMAA (β-N-methylamino-l-alanine) and DAB (2,4-diaminobutyric acid) in mollusks collected in shellfish production areas along the French coasts.

    PubMed

    Réveillon, Damien; Séchet, Véronique; Hess, Philipp; Amzil, Zouher

    2016-02-01

    The neurotoxin β-N-methylamino-l-alanine (BMAA) is naturally present in some microalgal species in the marine environment. The accumulation of BMAA has widely been observed in filter-feeding bivalves that are known to consume primary producers constituting the base of complex aquatic food webs. This study was performed to assess the occurrence of BMAA and isomers in mollusks collected from nine representative shellfish production areas located on the three French coasts (Channel, Atlantic and Mediterranean sites). The use of a highly selective and sensitive HILIC-MS/MS method, with D5DAB as internal standard, revealed the systematic detection of BMAA and DAB, in concentrations ranging from 0.20 to 6.7 μg g(-1) dry weight of digestive gland tissues of mollusks. While we detected BMAA in four strains of diatoms in a previous study, here BMAA was only detected in one diatom species previously not investigated out of the 23 microalgal species examined (belonging to seven classes). The concentrations of BMAA and DAB in mussels and oysters were similar at different sampling locations and despite the high diversity of phytoplankton populations that mollusks feed on at these locations. Only small variations of BMAA and DAB levels were observed and these were not correlated to any of the phytoplankton species reported. Therefore, extensive research should be performed on both origin and metabolism of BMAA in shellfish. The levels observed in this study are similar to those found in other studies in France or elsewhere. A previous study had related such levels to a cluster of Amyotrophic Lateral Sclerosis in the South of France; hence the widespread occurrence of BMAA in shellfish from all coasts in France found in this study suggests the need for further epidemiological and toxicological studies to establish the levels that are relevant for a link between the consumption of BMAA-containing foodstuffs and neurodegenerative diseases.

  14. Liquid chromatographic determination of the cyanobacterial toxin beta-n-methylamino-L-alanine in algae food supplements, freshwater fish, and bottled water.

    PubMed

    Scott, Peter M; Niedzwiadek, Barbara; Rawn, Dorothea F K; Lau, Ben P-Y

    2009-08-01

    Beta-N-Methylamino-L-alanine (BMAA) is a neurotoxin originally found in cycad seeds and now known to be produced by many species of freshwater and marine cyanobacteria. We developed a method for its determination in blue-green algae (BGA) food supplements, freshwater fish, and bottled water by using a strong cation-exchange, solid-phase extraction column for cleanup after 0.3 M trichloroacetic acid extraction of BGA supplements and fish. Bottled water was applied directly onto the solid-phase extraction column. For analysis of carbonated water, sonication and pH adjustment to 1.5 were needed. To determine protein-bound BMAA, the protein pellet left after extraction of the BGA supplement and fish was hydrolyzed by boiling with 6 M hydrochloric acid; BMAA was cleaned up on a C18 column and a strong cation-exchange, solid-phase extraction column. Determination of BMAA was by liquid chromatography of the fluorescent derivative formed with 9-fluorenylmethyl chloroformate. The method was validated by recovery experiments using spiking levels of 1.0 to 10 microg/g for BGA supplements, 0.5 to 5.0 microg/g for fish, and 0.002 microg/g for bottled water; mean recoveries were in the range of 67 to 89% for BGA supplements and fish, and 59 to 92% for bottled water. Recoveries of BMAA from spiked extracts of hydrolyzed protein from BGA supplements and fish ranged from 66 to 83%. The cleanup developed provides a useful method for surveying foods and supplements for BMAA and protein-bound BMAA.

  15. A Highly Active and Negatively Charged Streptococcus pyogenes Lysin with a Rare d-Alanyl-l-Alanine Endopeptidase Activity Protects Mice against Streptococcal Bacteremia

    PubMed Central

    Lood, Rolf; Raz, Assaf; Molina, Henrik; Euler, Chad W.

    2014-01-01

    Bacteriophage endolysins have shown great efficacy in killing Gram-positive bacteria. PlyC, a group C streptococcal phage lysin, represents the most efficient lysin characterized to date, with a remarkably high specificity against different streptococcal species, including the important pathogen Streptococcus pyogenes. However, PlyC is a unique lysin, in terms of both its high activity and structure (two distinct subunits). We sought to discover and characterize a phage lysin active against S. pyogenes with an endolysin architecture distinct from that of PlyC to determine if it relies on the same mechanism of action as PlyC. In this study, we identified and characterized an endolysin, termed PlyPy (phage lysin from S. pyogenes), from a prophage infecting S. pyogenes. By in silico analysis, PlyPy was found to have a molecular mass of 27.8 kDa and a pI of 4.16. It was active against a majority of group A streptococci and displayed high levels of activity as well as binding specificity against group B and C streptococci, while it was less efficient against other streptococcal species. PlyPy showed the highest activity at neutral pH in the presence of calcium and NaCl. Surprisingly, its activity was not affected by the presence of the group A-specific carbohydrate, while the activity of PlyC was partly inhibited. Additionally, PlyPy was active in vivo and could rescue mice from systemic bacteremia. Finally, we developed a novel method to determine the peptidoglycan bond cleaved by lysins and concluded that PlyPy exhibits a rare d-alanyl-l-alanine endopeptidase activity. PlyPy thus represents the first lysin characterized from Streptococcus pyogenes and has a mechanism of action distinct from that of PlyC. PMID:24637688

  16. β-N-Methylamino-L-alanine exposure alters defense against oxidative stress in aquatic plants Lomariopsis lineata, Fontinalis antipyretica, Riccia fluitans and Taxiphyllum barbieri.

    PubMed

    Contardo-Jara, Valeska; Funke, Marc Sebastian; Peuthert, Anja; Pflugmacher, Stephan

    2013-02-01

    Four different aquatic plants, the Pteridophyte Lomariopsis lineata and the Bryophytes Fontinalis antipyretica, Riccia fluitans and Taxiphyllum barbieri, were tested for their capacity to absorb the neurotoxin β-N-Methylamino-L-alanine (BMAA) from water and thus their possible applicability in a "Green Liver System". After exposure to 10 and 100 μg L(-1) BMAA for 1, 3, 7 and 14 days exposure concentration of medium and tissue were analyzed by LC-MS/MS. The amount removed by the plants within only 1 day was equal to the biological degradation of 14 days. Comparing the "BMAA-removal" capacity of the 4 tested aquatic plants R. fluitans, L. lineata and T. barbieri turned out to be most effective in cleaning the water from this cyanobacterial toxin by up to 97% within 14 days. Activity of the antioxidant enzymes peroxidase (POD) and catalase (CAT), as well as biotransformation enzyme glutathione S-transferase (GST) was compared between exposed and control plants to determine possible harmful effects induced by BMAA. Whereas the Bryophytes displayed increased POD activity and subsequent adaptation when exposed to the lower concentration, as well as partly inhibited antioxidant response at the higher applied BMAA concentration, the Pteridophyte L. lineata reacted with increased POD activity during the whole experiment and increased GST activity after longer exposure for 14 days. To give a recommendation of the suitability of an aquatic plant to be used for sustainable phytoremediation of contaminated water, testing of removal capacity of specific contaminants as well as studying general physiological parameters giving hint on survivability in such environments has to be combined. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. A critical review of the postulated role of the non-essential amino acid, β-N-methylamino-L-alanine, in neurodegenerative disease in humans.

    PubMed

    Chernoff, N; Hill, D J; Diggs, D L; Faison, B D; Francis, B M; Lang, J R; Larue, M M; Le, T-T; Loftin, K A; Lugo, J N; Schmid, J E; Winnik, W M

    2017-01-01

    The compound BMAA (β-N-methylamino-L-alanine) has been postulated to play a significant role in four serious neurological human diseases: Amyotrophic Lateral Sclerosis/Parkinsonism Dementia Complex (ALS/PDC) found on Guam, and ALS, Parkinsonism, and dementia that occur globally. ALS/PDC with symptoms of all three diseases first came to the attention of the scientific community during and after World War II. It was initially associated with cycad flour used for food because BMAA is a product of symbiotic cycad root-dwelling cyanobacteria. Human consumption of flying foxes that fed on cycad seeds was later suggested as a source of BMAA on Guam and a cause of ALS/PDC. Subsequently, the hypothesis was expanded to include a causative role for BMAA in other neurodegenerative diseases including Alzheimer's disease (AD) through exposures attributed to proximity to freshwaters and/or consumption of seafood due to its purported production by most species of cyanobacteria. The hypothesis that BMAA is the critical factor in the genesis of these neurodegenerative diseases received considerable attention in the medical, scientific, and public arenas. This review examines the history of ALS/PDC and the BMAA-human disease hypotheses; similarities and differences between ALS/PDC and the other diseases with similar symptomologies; the relationship of ALS/PDC to other similar diseases, studies of BMAA-mediated effects in lab animals, inconsistencies and data gaps in the hypothesis; and other compounds and agents that were suggested as the cause of ALS/PDC on Guam. The review concludes that the hypothesis of a causal BMAA neurodegenerative disease relationship is not supported by existing data.

  18. β-N-methylamino-l-alanine causes neurological and pathological phenotypes mimicking Amyotrophic Lateral Sclerosis (ALS): the first step towards an experimental model for sporadic ALS.

    PubMed

    de Munck, Estefanía; Muñoz-Sáez, Emma; Miguel, Begoña G; Solas, M Teresa; Ojeda, Irene; Martínez, Ana; Gil, Carmen; Arahuetes, Rosa Ma

    2013-09-01

    β-N-methylamino-l-alanine (L-BMAA) is a neurotoxic amino acid that has been related to various neurodegenerative diseases. The aim of this work was to analyze the biotoxicity produced by L-BMAA in vivo in rats, trying to elucidate its physiopathological mechanisms and to search for analogies between the found effects and pathologies like Amyotrophic Lateral Sclerosis (ALS). Our data demonstrated that the neurotoxic effects in vivo were dosage-dependent. For evaluating the state of the animals, a neurological evaluation scale was developed as well as a set of functional tests. Ultrastructural cell analysis of spinal motoneurons has revealed alterations both in endoplasmic reticulum and mitochondria. Since GSK3β could play a role in some neuropathological processes, we analyzed the alterations occurring in GSK3β levels in L-BMAA treated rats, we have observed an increase in the active form of GSK3β levels in lumbar spinal cord and motor cerebral cortex. On the other hand, (TAR)-DNA-binding protein 43 (TDP-43) increased in L-BMAA treated animals. Our results indicated that N-acetylaspartate (NAA) declined in animals treated with L-BMAA, and the ratio of N-acetylaspartate/choline (NAA/Cho), N-acetylaspartate/creatine (NAA/Cr) and N-acetylaspartate/choline+creatine (NAA/Cho+Cr) tended to decrease in lumbar spinal cord and motor cortex. This project offers some encouraging results that could help establishing the progress in the development of an animal model of sporadic ALS and L-BMAA could be a useful tool for this purpose. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Phase matching, X-Ray topography, optical and thermal analysis of L-alanine cadmium chloride monohydrate: a nonlinear optical material

    NASA Astrophysics Data System (ADS)

    Krishna, Anuj; Vijayan, N.; Riscob, B.; Gour, B. S.; Haranath, D.; Philip, J.; Verma, S.; Jayalakshmy, M. S.; Bhagavannarayana, G.; Halder, S. K.

    2014-03-01

    A potential semiorganic nonlinear optical material, L-alanine cadmium chloride monohydrate has been successfully synthesised and single crystals have been grown by slow evaporation solution growth technique at room temperature by using double distilled water as the solvent. The lattice dimensions of the grown crystal have been analysed by adopting powder X-ray diffraction technique and found that it crystallised in monoclinic system with space group C2. The crystalline perfection of the as-grown crystal has been assessed by high resolution X-ray diffraction and X-ray topography techniques and observed that the quality of the grown specimen is reasonably good. Its optical properties were examined by UV-Vis and photoluminescence techniques and found that there is no absorption in the entire visible range. Its functional groups were identified from FT-Raman and observed that there is no incorporation of other impurities during crystallisation. Its relative second harmonic generation efficiency has been tested with different particle size by Kurtz powder technique and found that within the coherence length the title compound is phase matchable. Its various thermal properties like thermal conductivity, specific heat, thermal effusivity, etc. have been evaluated by photopyroelectric technique and compared with other organic and inorganic materials. To confirm its piezoelectric response, its piezoelectric charge coefficient was measured using piezometer and found low. Its optical homogeneity as well as birefringence measurement of the grown specimen has been carried out by interferometric technique. The surface defects of the grown LACCM single crystal were analysed with etching at room temperature using water as an etchant.

  20. Differential effect of beta-N-oxalylamino-L-alanine, the Lathyrus sativus neurotoxin, and (+/-)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate on the excitatory amino acid and taurine levels in the brain of freely moving rats.

    PubMed

    La Bella, V; Piccoli, F

    2000-05-01

    We studied the effect of beta-oxalylamino-L-alanine, a glutamate analog present in Lathyrus sativus seeds and implicated in the etiopathogenesis of neurolathyrism, and (+/-)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate on the extracellular levels of aspartate, glutamate and taurine in the primary motor cortex of freely moving rats. We found that while both neurotoxins increase the level of aspartate and glutamate, only (+/-)-alpha(-amino-3-hydroxy-5-methylisoxazole-4-propionate is able to modulate the level of taurine. GYKI-52466, a non-competitive non-NMDA antagonist, inhibited beta-oxalylamino-L-alanine-induced increase of aspartate, but not that of glutamate. Conversely, this antagonist proved to be very efficient in blocking the stimulating effect of (+/-)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate on all three amino acids. We suggest that beta-oxalylamino-L-alanine increases the level of glutamate in vivo by a mechanism not connected to its effect on the non-NMDA receptors, which might involve the inhibition of glutamate transport. This would allow the excitatory neurotransmitter to reach a concentration sufficient to stimulate the non-NMDA receptors, which in their turn mediate the specific release of aspartate. Although the role of aspartate as a neurotransmitter is still under discussion, it might indeed amplify the excitotoxic cascade through its action on NMDA receptors. We speculate that this sequence of events might represent an important step in the molecular cascade leading to the appearance of the selective motoneuron degeneration in neurolathyrism.

  1. ALS-linked SOD1 in glial cells enhances ß-N-Methylamino L-Alanine (BMAA)-induced toxicity in Drosophila

    PubMed Central

    Islam, Rafique; Zhang, Bing

    2012-01-01

    Environmental factors have been implicated in the etiology of a number of neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). However, the role of environmental agents in ALS remains poorly understood. To this end, we used transgenic fruit flies (Drosophila melanogaster) to explore the interaction between mutant superoxide dismutase 1 (SOD1) and chemicals such as ß-N-methylamino L-alanine (BMAA), the herbicide agent paraquat, and superoxide species. We expressed ALS-linked human SOD1 (hSOD1A4V, and hSOD1G85R), hSOD1wt as well as the Drosophila native SOD1 (dSOD1) in motoneurons (MNs) or in glial cells alone and simultaneously in both types of cells. We then examined the effect of BMAA (3 mM), paraquat (20 mM), and hydrogen peroxide (H2O2, 1%) on the lifespan of SOD1-expressing flies. Our data show that glial expression of mutant and wild type hSOD1s reduces the ability of flies to climb. Further, we show that while all three chemicals significantly shorten the lifespan of flies, mutant SOD1 does not have a significant additional effect on the lifespan of flies fed on paraquat, but further shortens the lifespan of flies fed on H2O2. Finally, we show that BMAA shows a dramatic cell-type specific effect with mutant SOD1. Flies with expression of mutant hSOD1 in MNs survived longer on BMAA compared to control flies. In contrast, BMAA significantly shortened the lifespan of flies expressing mutant hSOD1 in glia. Consistent with a neuronal protection role, flies expressing these mutant hSOD1s in both MNs and glia also lived longer. Hence, our studies reveal a synergistic effect of mutant SOD1 with H2O2 and novel roles for mutant hSOD1s in neurons to reduce BMAA toxicity and in glia to enhance the toxicity of BMAA in flies. PMID:24627764

  2. ALS-linked SOD1 in glial cells enhances ß-N-Methylamino L-Alanine (BMAA)-induced toxicity in Drosophila.

    PubMed

    Islam, Rafique; Kumimoto, Emily L; Bao, Hong; Zhang, Bing

    2012-01-01

    Environmental factors have been implicated in the etiology of a number of neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). However, the role of environmental agents in ALS remains poorly understood. To this end, we used transgenic fruit flies (Drosophila melanogaster) to explore the interaction between mutant superoxide dismutase 1 (SOD1) and chemicals such as ß-N-methylamino L-alanine (BMAA), the herbicide agent paraquat, and superoxide species. We expressed ALS-linked human SOD1 (hSOD1A4V, and hSOD1G85R), hSOD1wt as well as the Drosophila native SOD1 (dSOD1) in motoneurons (MNs) or in glial cells alone and simultaneously in both types of cells. We then examined the effect of BMAA (3 mM), paraquat (20 mM), and hydrogen peroxide (H2O2, 1%) on the lifespan of SOD1-expressing flies. Our data show that glial expression of mutant and wild type hSOD1s reduces the ability of flies to climb. Further, we show that while all three chemicals significantly shorten the lifespan of flies, mutant SOD1 does not have a significant additional effect on the lifespan of flies fed on paraquat, but further shortens the lifespan of flies fed on H2O2. Finally, we show that BMAA shows a dramatic cell-type specific effect with mutant SOD1. Flies with expression of mutant hSOD1 in MNs survived longer on BMAA compared to control flies. In contrast, BMAA significantly shortened the lifespan of flies expressing mutant hSOD1 in glia. Consistent with a neuronal protection role, flies expressing these mutant hSOD1s in both MNs and glia also lived longer. Hence, our studies reveal a synergistic effect of mutant SOD1 with H2O2 and novel roles for mutant hSOD1s in neurons to reduce BMAA toxicity and in glia to enhance the toxicity of BMAA in flies.

  3. Antiferromagnetic spin chain behavior and a transition to 3D magnetic order in Cu(D,L-alanine)2: Roles of H-bonds

    NASA Astrophysics Data System (ADS)

    Calvo, Rafael; Sartoris, Rosana P.; Calvo, Hernán L.; Chagas, Edson F.; Rapp, Raul E.

    2016-05-01

    We study the spin chain behavior, a transition to 3D magnetic order and the magnitudes of the exchange interactions for the metal-amino acid complex Cu(D,L-alanine)2•H2O, a model compound to investigate exchange couplings supported by chemical paths characteristic of biomolecules. Thermal and magnetic data were obtained as a function of temperature (T) and magnetic field (B0). The magnetic contribution to the specific heat, measured between 0.48 and 30 K, displays above 1.8 K a 1D spin-chain behavior that can be fitted with an intrachain antiferromagnetic (AFM) exchange coupling constant 2J0=(-2.12±0.08) cm-1 (defined as ℋex(i,i+1) = -2J0SiṡSi+1), between neighbor coppers at 4.49 Å along chains connected by non-covalent and H-bonds. We also observe a narrow specific heat peak at 0.89 K indicating a phase transition to a 3D magnetically ordered phase. Magnetization curves at fixed T = 2, 4 and 7 K with B0 between 0 and 9 T, and at T between 2 and 300 K with several fixed values of B0 were globally fitted by an intrachain AFM exchange coupling constant 2J0=(-2.27±0.02) cm-1 and g = 2.091±0.005. Interchain interactions J1 between coppers in neighbor chains connected through long chemical paths with total length of 9.51 Å cannot be estimated from magnetization curves. However, observation of the phase transition in the specific heat data allows estimating the range 0.1≤|2J1|≤0.4 cm-1, covering the predictions of various approximations. We analyze the magnitudes of 2J0 and 2J1 in terms of the structure of the corresponding chemical paths. The main contribution in supporting the intrachain interaction is assigned to H-bonds while the interchain interactions are supported by paths containing H-bonds and carboxylate bridges, with the role of the H-bonds being predominant. We compare the obtained intrachain coupling with studies of compounds showing similar behavior and discuss the validity of the approximations allowing to calculate the interchain

  4. L-Alanyl-L-alanine in the zwitterionic state: structures determined in the presence of explicit water molecules and with continuum models using density functional theory

    NASA Astrophysics Data System (ADS)

    Knapp-Mohammady, M.; Jalkanen, K. J.; Nardi, F.; Wade, R. C.; Suhai, S.

    1999-01-01

    The structures and relative energies for L-alanyl-L-alanine (LALA) in the presence of explicit water molecules have been determined by using the density functional theory (DFT) Becke3-Lee-Yang-Parr functional and the 6-31G * basis set (B3LYP/6-31G *). In aqueous solution the dominant state of LALA is the zwitterionic form, while its neutral form is dominant in vacuo. Attempts to locate or determine a gas-phase zwitterionic species failed. That is, on the B3LYP/6-31G * potential energy surface, there is no barrier to proton transfer from the positively charged ammonium group to the negatively charged carboxylate group, or from the ammonium group to the adjacent carbonyl oxygen and from the amide nitrogen to the carboxylate group. To stabilize the zwitterion, we modelled the system by adding explicit water molecules and by placing the zwitterion within a sphere surrounded by a medium with a dielectric constant of 78.5, that is, within the Onsager continuum model, where the recommended cavity radius is obtained from a solute volume calculation. The zwitterionic species is only stable in the presence of water at the B3LYP/6-31G * level. This makes it imperative to include water molecules to model the zwitterionic species of LALA, peptides and amino acids at the B3LYP/6-31G * level. Finally, the zwitterionic structure stabilized by explicit water molecules has also been modelled within the Onsager theory. Here the Onsager model represents the effects due to the bulk water and the explicit water molecules stand for the effect due to direct H-bonding between the zwitterion and the solvent, that is, the first solvation shell. We used molecular dynamics simulations utilizing the CHARMm force field to produce structural input for the subsequent quantum-mechanical simulations. The structures determined using various methods to model the LALA zwitterionic form in aqueous solution were compared. We were able to find additional stable structures for LALA by adding water

  5. N- Trichloro- and dichloroacetyl amino acids and compounds of amino acids with halogeno acetic acids: 35Cl nuclear quadrupole resonance spectroscopy; crystal structure of N- trichloroacetyl- glycine, - DL-alanine, and - L-alanine

    NASA Astrophysics Data System (ADS)

    Dou, Shi-qi; Kehrer, Armin; Ofial, Armin R.; Weiss, Alarich

    1995-02-01

    The crystal structures of N- trichloroacetyl- glycine ( N- TCA- G), N-trichloroacetyl-dl-alanine ( N-TCA- dl-A ), and N-trichloroacetyl- l-alanine ( N-TCA- l-A ) were determined. In addition, the 35Cl NQR spectra of these N-trichloroacetyl amino acids, of N-trichloroacetyl- l-valine ( N-TCA- l-V ), and of N- dichloroacetyl- glycine and - L-alanine were measured, mostly as a function of temperature. Compounds of glycine and L-alanine with chlorodifluoroacetic acid, of glycine and L-leucine with monochloroacetic acid, of glycine and L-leucine with dichloroacetic acid, and of glycine and L-leucine with trichloroacetic acid were also studied using 35Cl NQR. The structures (in picometres and degrees) were found to be as follows. N- TCA- G: Pna2 1, Z = 8, a = 1641, b = 1002, c = 1018. N-TCA- dl-A : {C2}/{c}, Z = 8, a = 3280, b = 556, c = 1031, β = 96.68. N-TCA- l-A: P1 , Z = 2, a = 967, b = 949, c = 619, α = 74.97, β = 74.20, γ = 61.20. The 35Cl NQR frequencies (ν) were observed in the range 35-41 MHz, and decrease with increasing temperature. Some of the resonances bleach out at a temperature ( Tb) far below the melting temperature; this provides information about the crystal structures at 77 K. No phase transitions were observed by differential thermal analysis between 77 and 295 K. The crystal structures are discussed in connection with the NQR results, and conclusions are drawn about the structures of the compounds for which only 35Cl NQR data are available.

  6. Quantum yields of decomposition and homo-dimerization of solid L-alanine induced by 7.2 eV Vacuum ultraviolet light irradiation: an estimate of the half-life of L-alanine on the surface of space objects.

    PubMed

    Izumi, Yudai; Nakagawa, Kazumichi

    2011-08-01

    One of the leading hypotheses regarding the origin of prebiotic molecules on primitive Earth is that they formed from inorganic molecules in extraterrestrial environments and were delivered by meteorites, space dust and comets. To evaluate the availability of extraterrestrial amino acids, it is necessary to examine their decomposition and oligomerization rates as induced by extraterrestrial energy sources, such as vacuum ultraviolet (VUV) and X-ray photons and high energy particles. This paper reports the quantum yields of decomposition ((8.2 ± 0.7) × 10(-2) photon(-1)) and homo-dimerization ((1.2 ± 0.3) × 10(-3) photon(-1)) and decomposition of the dimer (0.24 ± 0.06 photon(-1)) of solid L-alanine (Ala) induced by VUV light with an energy of 7.2 eV. Using these quantum yields, the half-life of L-Ala on the surface of a space object in the present earth orbit was estimated to be about 52 days, even when only photons with an energy of 7.2 eV emitted from the present Sun were considered. The actual half-life of solid L-Ala on the surface of a space object orbit around the present day Earth would certainly be much shorter than our estimate, because of the added effect of photons and particles of other energies. Thus, we propose that L-Ala needs to be shielded from solar VUV in protected environments, such as the interior of a meteorite, within a time scale of days after synthesis to ensure its arrival on the primitive Earth.

  7. Structure of the O-polysaccharide of Proteus vulgaris O44: a new O-antigen that contains an amide of D-glucuronic acid with L-alanine.

    PubMed

    Toukach, Filip V; Perepelov, Andrei V; Bartodziejska, Beata; Shashkov, Alexander S; Blaszczyk, Aleksandra; Arbatsky, Nikolay P; Rozalski, Antoni; Knirel, Yuriy A

    2003-06-23

    The O-polysaccharide of Proteus vulgaris O44, strain PrK 67/57 was studied by 1H and 13C NMR spectroscopy, including 2D COSY, TOCSY, ROESY, H-detected 1H, 13C HMQC, HMQC-TOCSY and HMBC experiments. The polysaccharide was found to contain an amide of D-glucuronic acid with L-alanine [D-GlcA6(L-Ala)], and the following structure of the linear pentasaccharide repeating unit was established: [structure: see text]. The structural data of the O-polysaccharide and the results of serological studies with P. vulgaris O44 O-antiserum showed that the strain studied is unique among Proteus bacteria, which is in agreement with its classification in a separate Proteus serogroup, O44.

  8. Energetics of the molecular interactions of L-alanine and L-serine with xylitol, D-sorbitol, and D-mannitol in aqueous solutions at 298.15 K

    NASA Astrophysics Data System (ADS)

    Mezhevoi, I. N.; Badelin, V. G.

    2013-04-01

    Integral enthalpies of dissolution Δsol H m of L-alanine and L-serine are measured via the calorimetry of dissolution in aqueous solutions of xylitol, D-sorbitol, and D-mannitol. Standard enthalpies of dissolution (Δsol H ○) and the transfer (Δtr H ○) of amino acids from water to binary solvent are calculated from the experimental data. Using the McMillan-Mayer theory, enthalpy coefficients of pairwise interactions h xy of amino acids with molecules of polyols are calculated that are negative. The obtained results are discussed within the theory of the prevalence of different types of interactions in mixed solutions and the effect of the structural features of interacting biomolecules on the thermochemical parameters of dissolution of amino acids.

  9. Prolonged continuous intravenous infusion of the dipeptide L-alanine- L-glutamine significantly increases plasma glutamine and alanine without elevating brain glutamate in patients with severe traumatic brain injury

    PubMed Central

    2014-01-01

    Introduction Low plasma glutamine levels are associated with worse clinical outcome. Intravenous glutamine infusion dose- dependently increases plasma glutamine levels, thereby correcting hypoglutaminemia. Glutamine may be transformed to glutamate which might limit its application at a higher dose in patients with severe traumatic brain injury (TBI). To date, the optimal glutamine dose required to normalize plasma glutamine levels without increasing plasma and cerebral glutamate has not yet been defined. Methods Changes in plasma and cerebral glutamine, alanine, and glutamate as well as indirect signs of metabolic impairment reflected by increased intracranial pressure (ICP), lactate, lactate-to-pyruvate ratio, electroencephalogram (EEG) activity were determined before, during, and after continuous intravenous infusion of 0.75 g L-alanine-L-glutamine which was given either for 24 hours (group 1, n = 6) or 5 days (group 2, n = 6) in addition to regular enteral nutrition. Lab values including nitrogen balance, urea and ammonia were determined daily. Results Continuous L-alanine-L-glutamine infusion significantly increased plasma and cerebral glutamine as well as alanine levels, being mostly sustained during the 5 day infusion phase (plasma glutamine: from 295 ± 62 to 500 ± 145 μmol/ l; brain glutamine: from 183 ± 188 to 549 ± 120 μmol/ l; plasma alanine: from 327 ± 91 to 622 ± 182 μmol/ l; brain alanine: from 48 ± 55 to 89 ± 129 μmol/ l; p < 0.05, ANOVA, post hoc Dunn’s test). Plasma glutamate remained unchanged and cerebral glutamate was decreased without any signs of cerebral impairment. Urea and ammonia were significantly increased within normal limits without signs of organ dysfunction (urea: from 2.7 ± 1.6 to 5.5 ± 1.5 mmol/ l; ammonia: from 12 ± 6.3 to 26 ± 8.3 μmol/ l; p < 0.05, ANOVA, post hoc Dunn’s test). Conclusions High dose L-alanine-L-glutamine infusion (0

  10. Elucidation of matrix effects and performance of solid-phase extraction for LC-MS/MS analysis of β-N-methylamino-L-alanine (BMAA) and 2,4-diaminobutyric acid (DAB) neurotoxins in cyanobacteria.

    PubMed

    Li, Aifeng; Fan, Hua; Ma, Feifei; McCarron, Pearse; Thomas, Krista; Tang, Xianghai; Quilliam, Michael A

    2012-03-07

    A liquid chromatography-mass spectrometry (LC-MS/MS) method using hydrophilic interaction liquid chromatography (HILIC) was developed for the analysis of neurotoxins β-N-methylamino-L-alanine (BMAA) and 2,4-diaminobutyric acid (DAB), using multiple reaction monitoring (MRM) scan mode. Oasis-MCX and Strata-X-C polymeric cation-exchange cartridges were used to clean extracts of cyanobacterial cultures, including two strains of Microcystis aeruginosa and one strain of Nostoc sp. The performance of the solid-phase extraction (SPE) cartridges for BMAA and DAB were evaluated using mixed standards and spiked cyanobacterial extracts, which demonstrated recoveries of BMAA and DAB ranging from 66% to 91%. Matrix effects in LC-MS/MS were evaluated, and while there was no effect on BMAA quantitation, suppression of DAB was found. Full scan (Q1) and enhanced product ion (EPI) monitoring showed that the DAB suppression may be due to closely eluting compounds, including lysine, histidine, arginine and three other compounds with [M + H](+) m/z of 88, 164 and 191. The procedures developed allow the sensitive and effective analysis of trace BMAA and DAB levels in cyanobacteria. While DAB was confirmed to be present, no BMAA was found in the cyanobacterial samples tested in the present study.

  11. Improved detection of β-N-methylamino-L-alanine using N-hydroxysuccinimide ester of N-butylnicotinic acid for the localization of BMAA in blue mussels (Mytilus edulis).

    PubMed

    Andrýs, Rudolf; Zurita, Javier; Zguna, Nadezda; Verschueren, Klaas; De Borggraeve, Wim M; Ilag, Leopold L

    2015-05-01

    β-N-Methylamino-L-alanine (BMAA) is an important non-protein amino acid linked to neurodegenerative diseases, specifically amyotrophic lateral sclerosis (ALS). Because it can be transferred and bioaccumulated higher up the food chain, it poses significant public health concerns; thus, improved detection methods are of prime importance for the identification and management of these toxins. Here, we report the successful use of N-hydroxysuccinimide ester of N-butylnicotinic acid (C4-NA-NHS) for the efficient separation of BMAA from its isomers and higher sensitivity in detecting BMAA compared to the current method of choice using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) derivatization. Implementation of this efficient method allowed localization of BMAA in the non-visceral tissues of blue mussels, suggesting that more efficient depuration may be required to remove this toxin prior to consumption. This is a crucial method in establishing the absence or presence of the neurotoxic amino acid BMAA in food, environmental or biomedical samples.

  12. Determination of the neurotoxins BMAA (beta-N-methylamino-L-alanine) and DAB (alpha-,gamma-diaminobutyric acid) by LC-MSMS in Dutch urban waters with cyanobacterial blooms.

    PubMed

    Faassen, Elisabeth J; Gillissen, Frits; Zweers, Hans A J; Lürling, Miquel

    2009-01-01

    We aimed to determine concentrations of the neurotoxic amino acids beta-N-methylamino-L-alanine (BMAA) and alpha-,gamma-diaminobutyric acid (DAB) in mixed species scum material from Dutch urban waters that suffer from cyanobacterial blooms. BMAA and DAB were analysed in scum material without derivatization by LC-MSMS (liquid chromatography coupled to tandem mass spectrometry) using hydrophilic interaction chromatography (HILIC). Our method showed high selectivity, good recovery of added compounds after sample extraction (86% for BMAA and 85% for DAB), acceptable recovery after sample hydrolysation (70% for BMAA and 56% for DAB) and acceptable precision. BMAA and DAB could be detected at an injected amount of 0.34 pmol. Free BMAA was detected in nine of the 21 sampled locations with a maximum concentration of 42 microg/g DW. Free DAB was detected in two locations with a maximum concentration of 4 microg/g DW. No protein-associated forms were detected. This study is the first to detect underivatized BMAA in cyanobacterial scum material using LC-MSMS. Ubiquity of BMAA in cyanobacteria scums of Dutch urban waters could not be confirmed, where BMAA and DAB concentrations were relatively low; however, co-occurrence with other cyanobacterial neurotoxins might pose a serious health risk including chronic effects from low-level doses.

  13. LC-MS/MS determination of the isomeric neurotoxins BMAA (beta-N-methylamino-L-alanine) and DAB (2,4-diaminobutyric acid) in cyanobacteria and seeds of Cycas revoluta and Lathyrus latifolius.

    PubMed

    Krüger, Thomas; Mönch, Bettina; Oppenhäuser, Steven; Luckas, Bernd

    2010-01-01

    Since diverse taxa of cyanobacteria has been linked to biosynthesis of BMAA, a controversy has arisen about the detection of neurotoxic amino acids in cyanobacteria. In this context, a novel LC-MS/MS method was developed for the unambiguous determination of beta-N-methylamino-L-alanine (BMAA) and 2,4-diaminobutyric acid (DAB) in cyanobacteria and selected plant seeds. Both neurotoxic and non-proteinogenic amino acids were analyzed without derivatization considering the total concentration of the free and protein-bound form. The investigation of overall 62 cyanobacterial samples of worldwide origin by application of this method revealed the absence of BMAA, whereas seeds of Cycas revoluta contained 6.96 microg g(-1) of free BMAA. In contrast, the isomer DAB was confirmed in 16 cyanobacterial samples in concentrations of 0.07-0.83 microg g(-1),whereof one sample is distributed as nutritional supplement. In addition, seeds of Lathyrus latifolius contained 4.21 microg g(-1) of free DAB. Limits of detection were for BMAA<1.0 microg g(-1) in the cyanobacterial matrix and<0.14 microg g(-1) in angiosperm seeds. DAB exhibits higher sensitivities of <0.06 microg g(-1) in cyanobacteria and <0.008 microg g(-1) in angiosperm seeds. The highly specific analysis method with increased detection sensitivity eliminates the disadvantages of derivatization-based methods to be discussed.

  14. Retention of the cyanobacterial neurotoxin beta-N-methylamino-l-alanine in melanin and neuromelanin-containing cells--a possible link between Parkinson-dementia complex and pigmentary retinopathy.

    PubMed

    Karlsson, Oskar; Berg, Cecilia; Brittebo, Eva B; Lindquist, Nils Gunnar

    2009-02-01

    beta-N-methylamino-l-alanine (BMAA), a neurotoxic amino acid produced by cyanobacteria, has been suggested to be involved in the etiology of a neurodegenerative disease complex which includes Parkinson-dementia complex (PDC). In PDC, neuromelanin-containing neurons in substantia nigra are degenerated. Many PDC patients also have an uncommon pigmentary retinopathy. The aim of this study was to investigate the distribution of (3)H-BMAA in mice and frogs, with emphasis on pigment-containing tissues. Using autoradiography, a distinct retention of (3)H-BMAA was observed in melanin-containing tissues such as the eye and neuromelanin-containing neurons in frog brain. Analysis of the binding of (3)H-BMAA to Sepia melanin in vitro demonstrated two apparent binding sites. In vitro-studies with synthetic melanin revealed a stronger interaction of (3)H-BMAA with melanin during synthesis than the binding to preformed melanin. Long-term exposure to BMAA may lead to bioaccumulation in melanin- and neuromelanin-containing cells causing high intracellular levels, and potentially changed melanin characteristics via incorporation of BMAA into the melanin polymer. Interaction of BMAA with melanin may be a possible link between PDC and pigmentary retinopathy.

  15. Quality measures of imaging mass spectrometry aids in revealing long-term striatal protein changes induced by neonatal exposure to the cyanobacterial toxin β-N-methylamino-L-alanine (BMAA).

    PubMed

    Karlsson, Oskar; Bergquist, Jonas; Andersson, Malin

    2014-01-01

    Many pathological processes are not directly correlated to dramatic alterations in protein levels. The changes in local concentrations of important proteins in a subset of cells or at specific loci are likely to play a significant role in disease etiologies, but the precise location might be unknown, or the concentration might be too small to be adequately sampled for traditional proteomic techniques. Matrix-assisted laser desorption ionization (MALDI) imaging mass spectrometry (IMS) is a unique analytical method that combines analysis of multiple molecular species and of their distribution in a single platform. As reproducibility is essential for successful biomarker discovery, it is important to systematically assess data quality in biologically relevant MALDI IMS experiments. In the present study, we applied four simple tools to study the reproducibility for individual sections, within-group variation, and between-group variation of data acquired from brain sections of 21 animals divided into three treatment groups. We also characterized protein changes in distinct regions of the striatum from six-month-old rats treated neonatally (postnatal days 9-10) with the cyanobacterial toxin β-N-methylamino-l-alanine (BMAA), which has been implicated in neurodegenerative diseases. The results showed that optimized experimental settings can yield high-quality MALDI IMS data with relatively low variation (14% to 15% coefficient of variance) that allow the characterization of subtle changes in protein expression in various subregions of the brain. This was further exemplified by the dose-dependent reduction of myelin basic protein in the caudate putamen and the nucleus accumbens of adult rats neonatally treated with BMAA (150 and 460 mg/kg). The reduction in myelin basic protein was confirmed through immunohistochemistry and indicates that developmental exposure to BMAA may induce structural effects on axonal growth and/or directly on the proliferation of oligodendrocytes

  16. 2.0A resolution crystal structures of the ternary complexes of human phenylalanine hydroxylase catalytic domain with tetrahydrobiopterin and 3-(2-thienyl)-L-alanine or L-norleucine: substrate specificity and molecular motions related to substrate binding.

    PubMed

    Andersen, Ole Andreas; Stokka, Anne J; Flatmark, Torgeir; Hough, Edward

    2003-10-31

    The crystal structures of the catalytic domain of human phenylalanine hydroxylase (hPheOH) in complex with the physiological cofactor 6(R)-L-erythro-5,6,7,8-tetrahydrobiopterin (BH(4)) and the substrate analogues 3-(2-thienyl)-L-alanine (THA) or L-norleucine (NLE) have been determined at 2.0A resolution. The ternary THA complex confirms a previous 2.5A structure, and the ternary NLE complex shows that similar large conformational changes occur on binding of NLE as those observed for THA. Both structures demonstrate that substrate binding triggers structural changes throughout the entire protomer, including the displacement of Tyr138 from a surface position to a buried position at the active site, with a maximum displacement of 20.7A for its hydroxyl group. Two hinge-bending regions, centred at Leu197 and Asn223, act in consort upon substrate binding to create further large structural changes for parts of the C terminus. Thus, THA/L-Phe binding to the active site is likely to represent the epicentre of the global conformational changes observed in the full-length tetrameric enzyme. The carboxyl and amino groups of THA and NLE are positioned identically in the two structures, supporting the conclusion that these groups are of key importance in substrate binding, thus explaining the broad non-physiological substrate specificity observed for artificially activated forms of the enzyme. However, the specific activity with NLE as the substrate was only about 5% of that with THA, which is explained by the different affinities of binding and different catalytic turnover.

  17. ApoSOD1 lacking dismutase activity neuroprotects motor neurons exposed to beta-methylamino-L-alanine through the Ca2+/Akt/ERK1/2 prosurvival pathway

    PubMed Central

    Petrozziello, Tiziana; Secondo, Agnese; Tedeschi, Valentina; Esposito, Alba; Sisalli, MariaJosè; Scorziello, Antonella; Di Renzo, Gianfranco; Annunziato, Lucio

    2017-01-01

    Amyotrophic lateral sclerosis (ALS) is a severe human adult-onset neurodegenerative disease affecting lower and upper motor neurons. In >20% of cases, the familial form of ALS is caused by mutations in the gene encoding Cu,Zn-superoxide dismutase (SOD1). Interestingly, administration of wild-type SOD1 to SOD1G93A transgenic rats ameliorates motor symptoms through an unknown mechanism. Here we investigated whether the neuroprotective effects of SOD1 are due to the Ca2+-dependent activation of such prosurvival signaling pathway and not to its catalytic activity. To this aim, we also examined the mechanism of neuroprotective action of ApoSOD1, the metal-depleted state of SOD1 that lacks dismutase activity, in differentiated motor neuron-like NSC-34 cells and in primary motor neurons exposed to the cycad neurotoxin beta-methylamino-L-alanine (L-BMAA). Preincubation of ApoSOD1 and SOD1, but not of human recombinant SOD1G93A, prevented cell death in motor neurons exposed to L-BMAA. Moreover, ApoSOD1 elicited ERK1/2 and Akt phosphorylation in motor neurons through an early increase of intracellular Ca2+ concentration ([Ca2+]i). Accordingly, inhibition of ERK1/2 by siMEK1 and PD98059 counteracted ApoSOD1- and SOD1-induced neuroprotection. Similarly, transfection of the dominant-negative form of Akt in NSC-34 motor neurons and treatment with the selective PI3K inhibitor LY294002 prevented ApoSOD1- and SOD1-mediated neuroprotective effects in L-BMAA-treated motor neurons. Furthermore, ApoSOD1 and SOD1 prevented the expression of the two markers of L-BMAA-induced ER stress GRP78 and caspase-12. Collectively, our data indicate that ApoSOD1, which is devoid of any catalytic dismutase activity, exerts a neuroprotective effect through an early activation of Ca2+/Akt/ERK1/2 pro-survival pathway that, in turn, prevents ER stress in a neurotoxic model of ALS. PMID:28085149

  18. L-alanine-glyoxylate aminotransferase II of rat kidney and liver mitochondria possesses cysteine S-conjugate beta-lyase activity: a contributing factor to the nephrotoxicity/hepatotoxicity of halogenated alkenes?

    PubMed Central

    Cooper, Arthur J L; Krasnikov, Boris F; Okuno, Etsuo; Jeitner, Thomas M

    2003-01-01

    Several halogenated alkenes are metabolized in part to cysteine S-conjugates, which are mitochondrial toxicants of kidney and, to a lesser extent, other organs. Toxicity is due to cysteine S-conjugate beta-lyases, which convert the cysteine S-conjugate into pyruvate, ammonia and a reactive sulphur-containing fragment. A section of the human population is exposed to halogenated alkenes. To understand the health effects of such exposure, it is important to identify cysteine S-conjugate beta-lyases that contribute to mitochondrial damage. Mitochondrial aspartate aminotransferase [Cooper, Bruschi, Iriarte and Martinez-Carrion (2002) Biochem. J. 368, 253-261] and mitochondrial branched-chain aminotransferase [Cooper, Bruschi, Conway and Hutson (2003) Biochem. Pharmacol. 65, 181-192] exhibit beta-lyase activity toward S -(1,2-dichlorovinyl)-L-cysteine (the cysteine S-conjugate of trichloroethylene) and S -(1,1,2,2-tetrafluoroethyl)-L-cysteine (the cysteine S-conjugate of tetrafluoroethylene). Turnover leads to eventual inactivation of these enzymes. Here we report that mitochondrial L-alanine-glyoxylate aminotransferase II, which, in the rat, is most active in kidney, catalyses cysteine S-conjugate beta-lyase reactions with S -(1,1,2,2-tetrafluoroethyl)-L-cysteine, S -(1,2-dichlorovinyl)-L-cysteine and S -(benzothiazolyl-L-cysteine); turnover leads to inactivation. Previous workers showed that the reactive-sulphur-containing fragment released from S -(1,1,2,2-tetrafluoroethyl)-L-cysteine and S -(1,2-dichlorovinyl)-L-cysteine is toxic by acting as a thioacylating agent - particularly of lysine residues in nearby proteins. Toxicity, however, may also involve 'self-inactivation' of key enzymes. The present findings suggest that alanine-glyoxylate aminotransferase II may be an important factor in the well-established targeting of rat kidney mitochondria by toxic halogenated cysteine S-conjugates. Previous reports suggest that alanine-glyoxylate aminotransferase II is absent

  19. Equilibrated diet restores the effects of early age choline-deficient feeding on rat brain antioxidant status and enzyme activities: the role of homocysteine, L-phenylalanine and L-alanine.

    PubMed

    Liapi, Charis; Feskou, Irini; Zarros, Apostolos; Carageorgiou, Haris; Galanopoulou, Panagiota; Tsakiris, Stylianos

    2008-09-01

    Choline is an essential nutrient that seems to be involved in a wide variety of metabolic reactions and functions, that affect the developing brain. The aim of this study was to: (a)examine the effects of early age choline deficient diet (CDD) administration on the total antioxidant status (TAS) and the activities of acetylcholinesterase (AChE), (Na(+),K(+))-ATPase and Mg(2+)-ATPase in the rat brain, (b)investigate the effect of feeding restoration into an equilibrated diet on the above parameters, and (c)study the role of homocysteine (Hcy), L: -phenylalanine (Phe) and L: -alanine (Ala) in certain of the above effects. Male and female Wistar rats were continuously kept off choline (Ch) during their gestational period of life, as well as during the first 6 weeks of their post-gestational life. The animals were sacrificed by decapitation and their whole brains were rapidly removed and homogenated. Their enzyme activities were measured spectrophotometrically. Moreover, in vitro experiments were conducted in order to estimate the effects of Hcy (0.3 mM), Phe (1.2 mM) and/or Ala (1.2 mM) on the above parameters. The administration of CDD led to a statistically significant decrease of the rat brain TAS (-29%, p < 0.001) and to a significant increase of both AChE (+20%, p < 0.001) and (Na(+),K(+))-ATPase (+35%, p < 0.001) activities. Mg(2+)-ATPase activity was found unaltered. Equilibrated diet, administered to early age CDD-treated rats of both sexes for an additional period of 18 weeks, restored the above parameters to control levels. Moreover, the in vitro experiments showed that Hcy could simulate these changes (at least under the examined in vitro conditions), while both Phe and Ala act protectively against the CDD-induced effects on the examined rat brain enzyme activities. The effects of early age CDD-feeding on the examined parameters are proved to be reversible through restoration to equilibrated diet, while our data suggest a role for Hcy (as a causative

  20. Crystal structure of the ternary complex of the catalytic domain of human phenylalanine hydroxylase with tetrahydrobiopterin and 3-(2-thienyl)-L-alanine, and its implications for the mechanism of catalysis and substrate activation.

    PubMed

    Andersen, Ole Andreas; Flatmark, Torgeir; Hough, Edward

    2002-07-26

    Phenylalanine hydroxylase catalyzes the stereospecific hydroxylation of L-phenylalanine, the committed step in the degradation of this amino acid. We have solved the crystal structure of the ternary complex (hPheOH-Fe(II).BH(4).THA) of the catalytically active Fe(II) form of a truncated form (DeltaN1-102/DeltaC428-452) of human phenylalanine hydroxylase (hPheOH), using the catalytically active reduced cofactor 6(R)-L-erythro-5,6,7,8-tetrahydrobiopterin (BH(4)) and 3-(2-thienyl)-L-alanine (THA) as a substrate analogue. The analogue is bound in the second coordination sphere of the catalytic iron atom with the thiophene ring stacking against the imidazole group of His285 (average interplanar distance 3.8A) and with a network of hydrogen bonds and hydrophobic contacts. Binding of the analogue to the binary complex hPheOH-Fe(II).BH(4) triggers structural changes throughout the entire molecule, which adopts a slightly more compact structure. The largest change occurs in the loop region comprising residues 131-155, where the maximum r.m.s. displacement (9.6A) is at Tyr138. This loop is refolded, bringing the hydroxyl oxygen atom of Tyr138 18.5A closer to the iron atom and into the active site. The iron geometry is highly distorted square pyramidal, and Glu330 adopts a conformation different from that observed in the hPheOH-Fe(II).BH(4) structure, with bidentate iron coordination. BH(4) binds in the second coordination sphere of the catalytic iron atom, and is displaced 2.6A in the direction of Glu286 and the iron atom, relative to the hPheOH-Fe(II).BH(4) structure, thus changing its hydrogen bonding network. The active-site structure of the ternary complex gives new insight into the substrate specificity of the enzyme, notably the low affinity for L-tyrosine. Furthermore, the structure has implications both for the catalytic mechanism and the molecular basis for the activation of the full-length tetrameric enzyme by its substrate. The large conformational change, moving

  1. Innovative effect of illite on improved microbiological conversion of L-tyrosine to 3,4 dihydroxy phenyl L-alanine (L-DOPA) by Aspergillus oryzae ME2 under acidic reaction conditions.

    PubMed

    Sikander, Ali; Ikram-ul-Haq

    2006-11-01

    In the present investigation, the previous ultraviolet irradiated mutant strain of Aspergillus oryzae UV-7 was further improved in terms of 3,4 dihydroxy phenyl L-alanine (L-DOPA) activity after chemical mutagenesis through 1-methyl 3-nitro 1-nitroso guanidine (MNNG = 250-1500 microg/ml) treatment (0-30 min). Among several mutant variants, the one that produced a larger amount of L-DOPA from L-tyrosine was designated to as ME2 and it was made 2-deoxy-D-glucose-resistant by growing it at various concentrations of 2 dg (0.01-0.025 %, w/v) in Vogel's agar medium. Relatively better production of L-DOPA (> 0.60 mg/ml) was obtained when 2.0% (w/v) glucose was used as a carbon source in the mycelium production medium and the tyrosinase activity increased constitutively (1.08 mg/ml), which resulted in a greater production of L-DOPA. At optimum pH0 (pH 6.0) and reaction time (60 min), more than 65% sugar was utilized for cell mass formation. The maximum conversion of L-tyrosine to L-DOPA (0.428 mg/ml) was achieved 60 min after the biochemical reaction. Mould mycelium was used for microbiological conversion of L-tyrosine to L-DOPA because tyrosinases, beta-carboxylases, and tyrosine hydroxylases are intracellular enzymes. The effect of illite (1.0 x 10(6)-6.0 x 10(6) M) on biochemical conversion of L-tyrosine to L-DOPA by Aspergillus oryzae ME(2 )was also carried out. Best results of L-DOPA biosynthesis were observed when the concentration of illite was 3.5 x 10(-6) M (1.686 mg/ml L-DOPA produced with 1.525 mg/ml consumption of L-tyrosine). It was noted that the addition of illite not only increased enzyme activity but also enhanced the permeability of cell membrane to facilitate the secretion of enzymes into the reaction broth. The comparison of kinetic parameters showed the ability of mutant to yield L-DOPA (i.e., Yp/x 7.360 +/- 0.04 mg/mg). When the culture grown on various illite concentrations was monitored for Qp, Qs, and qp, there was significant enhancement (p < 0

  2. Computation of energy interaction parameters as well as electric dipole intensity parameters for the absorption spectral study of the interaction of Pr(III) with L-phenylalanine, L-glycine, L-alanine and L-aspartic acid in the presence and absence of Ca 2+ in organic solvents

    NASA Astrophysics Data System (ADS)

    Moaienla, T.; Singh, Th. David; Singh, N. Rajmuhon; Devi, M. Indira

    2009-10-01

    Studying the absorption difference and comparative absorption spectra of the interaction of Pr(III) and Nd(III) with L-phenylalanine, L-glycine, L-alanine and L-aspartic acid in the presence and absence of Ca 2+ in organic solvents, various energy interaction parameters like Slater-Condon ( FK), Racah ( Ek), Lande factor ( ξ4f), nephelauxetic ratio ( β), bonding ( b1/2), percentage-covalency ( δ) have been evaluated applying partial and multiple regression analysis. The values of oscillator strength ( P) and Judd-Ofelt electric dipole intensity parameter Tλ ( λ = 2, 4, 6) for different 4f-4f transitions have been computed. On analysis of the variation of the various energy interaction parameters as well as the changes in the oscillator strength ( P) and Tλ values reveal the mode of binding with different ligands.

  3. Transfer Partial Molar Isentropic Compressibilities of ( l-Alanine/ l-Glutamine/Glycylglycine) from Water to 0.512 {mol} \\cdot {kg}^{-1} Aqueous {KNO}3/0.512 {mol} \\cdot {kg}^{-1} Aqueous {K}2{SO}4 Solutions Between 298.15 K and 323.15 K

    NASA Astrophysics Data System (ADS)

    Riyazuddeen; Gazal, Umaima

    2013-03-01

    Speeds of sound of ( l-alanine/ l-glutamine/glycylglycine + 0.512 {mol}\\cdot {kg}^{-1} aqueous {KNO}3/0.512 {mol}\\cdot {kg}^{-1} aqueous {K}2{SO}4) systems have been measured for several molal concentrations of amino acid/peptide at different temperatures: T = (298.15 to 323.15) K. Using the speed-of-sound and density data, the parameters, partial molar isentropic compressibilities φ _{kappa }0 and transfer partial molar isentropic compressibilities Δ _{tr} φ _{kappa }0, have been computed. The trends of variation of φ _{kappa }0 and Δ _{tr} φ _{kappa }0 with changes in molal concentration of the solute and temperature have been discussed in terms of zwitterion-ion, zwitterion-water dipole, ion-water dipole, and ion-ion interactions operative in the systems.

  4. Ruthenium-Nitrosyl Complexes with Glycine, l-Alanine, l-Valine, l-Proline, d-Proline, l-Serine, l-Threonine, and l-Tyrosine: Synthesis, X-ray Diffraction Structures, Spectroscopic and Electrochemical Properties, and Antiproliferative Activity

    PubMed Central

    2014-01-01

    The reactions of [Ru(NO)Cl5]2– with glycine (Gly), l-alanine (l-Ala), l-valine (l-Val), l-proline (l-Pro), d-proline (d-Pro), l-serine (l-Ser), l-threonine (l-Thr), and l-tyrosine (l-Tyr) in n-butanol or n-propanol afforded eight new complexes (1–8) of the general formula [RuCl3(AA–H)(NO)]−, where AA = Gly, l-Ala, l-Val, l-Pro, d-Pro, l-Ser, l-Thr, and l-Tyr, respectively. The compounds were characterized by elemental analysis, electrospray ionization mass spectrometry (ESI-MS), 1H NMR, UV–visible and ATR IR spectroscopy, cyclic voltammetry, and X-ray crystallography. X-ray crystallography studies have revealed that in all cases the same isomer type (from three theoretically possible) was isolated, namely mer(Cl),trans(NO,O)-[RuCl3(AA–H)(NO)], as was also recently reported for osmium analogues with Gly, l-Pro, and d-Pro (see Z. Anorg. Allg. Chem.2013, 639, 1590–1597). Compounds 1, 4, 5, and 8 were investigated by ESI-MS with regard to their stability in aqueous solution and reactivity toward sodium ascorbate. In addition, cell culture experiments in three human cancer cell lines, namely, A549 (nonsmall cell lung carcinoma), CH1 (ovarian carcinoma), and SW480 (colon carcinoma), were performed, and the results are discussed in conjunction with the lipophilicity of compounds. PMID:24555845

  5. Effects of L-Alanine and Inosine Germinants on the Elasticity of Bacillus anthracis Spores

    DTIC Science & Technology

    2010-01-22

    surface of dormant Bacillus anthracis spores consists of a multilayer of protein coats and a thick peptidoglycan layer that allow the cells to resist...spore coat and the peptidoglycan cortex that protects the spore core, which would change the mechanical properties of the cell. Spores treated with lower

  6. β-N-Methylamino-L-alanine (BMAA) uptake by the aquatic macrophyte Ceratophyllum demersum.

    PubMed

    Esterhuizen, M; Pflugmacher, S; Downing, T G

    2011-01-01

    Free-living freshwater cyanobacteria contain BMAA in both free cellular and protein-associated forms. Free BMAA released on bloom collapse or during cellular turnover creates a potential source of the non-proteinogenic amino acid for bioaccumulation and biomagnification in aquatic ecosystems. Uptake of free amino acids is well documented in macrophytes and the potential for aquatic macrophytes to bioaccumulate BMAA therefore poses a potential threat where such macrophytes constitute a food source in an ecosystem. BMAA uptake and accumulation by the aquatic macrophyte Ceratophyllum demersum was therefore investigated. Rapid uptake of significant amounts of BMAA was observed in C. demersum. Both free and protein-associated BMAA were observed with protein association following accumulation of free BMAA. The protein association suggests potential biomaccumulation by aquatic macrophytes and offers a possibility of phytoremediation for BMAA removal.

  7. Excitotoxic potential of the cyanotoxin β-methyl-amino-L-alanine (BMAA) in primary human neurons.

    PubMed

    Chiu, Alexander S; Gehringer, Michelle M; Braidy, Nady; Guillemin, Gilles J; Welch, Jeffrey H; Neilan, Brett A

    2012-11-01

    The toxicity of the cyanobacterial modified amino acid, BMAA, has been described in rat, mouse and leech neurons. Particular emphasis has been placed on the potential ability of BMAA to induce neuronal damage via excitotoxic mechanisms. Here we present data indicating that the effects observed on lower organisms are also evident in a human model. Our data indicates that BMAA induces increased intracellular Ca²⁺ influx, DNA damage, mitochondrial activity, lactate dehydrogenase (LDH) release and generation of reactive oxygen species (ROS). The amelioration of LDH release in the presence of the N-methyl-D-aspartate (NMDA) receptor antagonist MK801 indicates that the neurotoxic effects of BMAA are mediated via NMDA receptor activation. Additionally, we have shown that BMAA induces the expression of neuronal nitric oxide synthase (nNOS) and caspase-3 indicating that it can stimulate apoptosis in human neurons, presumably via activation of NMDA receptors.

  8. Analysis of β-N-methylamino-L-alanine (L-BMAA) neurotoxicity in rat cerebellum.

    PubMed

    Muñoz-Sáez, Emma; de Munck García, Estefanía; Arahuetes Portero, Rosa Ma; Martínez, Ana; Solas Alados, Ma Teresa; Miguel, Begoña Gómez

    2015-05-01

    Due to its structural similarity to glutamate, L-BMAA could be a trigger for neurodegenerative disorders caused by changes in the intracellular medium, such as increased oxidative stress, mitochondrial dysfunction, impaired synthesis and protein degradation and the imbalance of some enzymes. It is also important to note that according to some published studies, L-BMAA will be incorporated into proteins, causing the alteration of protein homeostasis. Neuronal cells are particularly prone to suffer damage in protein folding and protein accumulation because they have not performed cellular division. In this work, we will analyse the cerebellum impairment triggered by L-BMAA in treated rats. The cerebellum is one of the most important subcortical motor centres and ensures that movements are performed with spatial and temporal precision. Cerebellum damage caused by L-BMAA can contribute to motor impairment. To characterize this neurodegenerative pathology, we first carried out ultrastructure analysis in Purkinje cells showing altered mitochondria, endoplasmic reticulum (ER), and Golgi apparatus (GA). We then performed biochemical assays of GSK3 and TDP-43 in cerebellum, obtaining an increase of both biomarkers with L-BMAA treatment and, finally, performed autophagy studies that revealed a higher level of these processes after treatment. This work provides evidence of cerebellar damage in rats after treatment with L-BMAA. Three months after treatment, affected rats cannot restore the normal functions of the cerebellum regarding motor coordination and postural control. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Chiral effects on helicity studied via the energy landscape of short (D, L)-alanine peptides.

    PubMed

    Neelamraju, Sridhar; Oakley, Mark T; Johnston, Roy L

    2015-10-28

    The homochirality of natural amino acids facilitates the formation of regular secondary structures such as α-helices and β-sheets. Here, we study the relationship between chirality and backbone structure for the example of hexa-alanine. The most stable stereoisomers are identified through global optimisation. Further, the energy landscape, a database of connected low-energy local minima and transition points, is constructed for various neutral and zwitterionic stereoisomers of hexa-alanine. Three order parameters for partial helicity are applied and metric disconnectivity graphs are presented with partial helicity as a metric. We also apply the Zimm-Bragg model to derive average partial helicities for Ace-(L-Ala)6-NHMe, Ace-(D-Ala-L-Ala)3-NHMe, and Ace-(L-Ala)3-(D-Ala)3-NHMe from the database of local minima and compare with previous studies.

  10. Neurochemical and neurobehavioral effects of neonatal administration of beta-N-methylamino-L-alanine and 3,3'-iminodipropionitrile.

    PubMed

    Dawson, R; Marschall, E G; Chan, K C; Millard, W J; Eppler, B; Patterson, T A

    1998-01-01

    Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that is characterized by a loss of motor neurons in the spinal cord, brain stem, and cortex. The present study examined the neurochemical and neurobehavioral consequences of the neonatal administration of IDPN and BMAA, two neurotoxins previously considered as experimental models of ALS. Sprague-Dawley rat pups (male and female) were injected SC with IDPN or BMAA. The following treatment groups (n = 5-14 per group) were studied; IDPN [100 mg/kg on postnatal days (PNDs) 2, 4, and 6], BMAA-A (500 mg/kg PND 5 only), BMAA-B (500 mg/kg PND 2 and 5), and BMAA-C (100 mg/kg PND 2 and 5). Neurobehavioral testing was performed and the rats were sacrificed at 101 days of age. Monoamine and amino acid content was measured by HPLC in brain regions and the spinal cord. IDPN treatment impaired the righting reflex and decreased forepaw suspension times. BMAA-A and BMAA-B males exhibited an increase in open field behavior. The hindlimb splay of BMAA-A females was increased. Other significant behavioral and endocrine effects were also seen with neonatal IDPN or BMAA treatment. IDPN females had increased spinal cord content of norepinephrine (NE), serotonin, and 5-hydroxyindoleacetic acid (5-HIAA). IDPN males had no alterations in spinal cord content of NE or Glu, but serotonin and 5-HIAA content were increased. BMAA-A and BMAA-B males also had elevated spinal cord 5-HIAA content whereas females were unaffected. Glu and Asp content in the spinal cord was elevated in the female BMAA-C group. Monoamines were also altered in the cerebellum, mediobasal hypothalamus, and hippocampus by IDPN and BMAA treatment. alpha 2-Adrenergic binding sites were increased in the spinal cord by IDPN and in the cerebellum by BMAA treatment. The results of this study clearly demonstrated that both IDPN and BMAA given neonatally can produce changes in motor function and spinal cord neurochemistry, although the pattern of the effects is both treatment and sex dependent. Neonatal exposure to either IDPN or BMAA resulted in permanent changes in adult neurochemistry that may be related to reorganizational effects induced by toxin-mediated neuroplasticity in developing neurons.

  11. Growth, structural, spectral, mechanical and dielectric characterization of RbCl-doped L-alanine hydrogen chloride monohydrate single crystals

    NASA Astrophysics Data System (ADS)

    Lucia Rose, A. S. J.; Selvarajan, P.; Perumal, S.

    2011-02-01

    Pure (undoped) and RbCl-doped LAHC single crystals were grown successfully by the solution method with the slow evaporation technique at room temperature. The grown crystals were colourless and transparent. The solubility of the grown samples were found out at various temperatures. The lattice parameters of the grown crystals were determined by the single crystal X-ray diffraction technique and the diffracting planes were indentified by recording the powder X-ray diffraction pattern. UV-visible transmittance studies were carried out for the grown samples. Chemical analysis and atomic absorption studies indicate the presence of rubidium in the doped LAHC crystals. Nonlinear optical studies reveal that the SHG efficiency increases when the LAHC crystal is doped with rubidium chloride (RbCl). From microhardness studies, it is observed that the RbCl-doped LAHC crystal is harder than the pure sample. It is observed that the dielectric properties of the LAHC crystal are altered when it is doped with rubidium chloride.

  12. Failure to Detect the Neurotoxin Beta-n-methylamino-l-alanine in Samples Collected during an Avian Vacuolar Myelinopathy (AVM) Epornitic in J. Strom Thurmond Lake

    DTIC Science & Technology

    2015-08-01

    and Alzheimer ???s Disease (AD). This compound was previously detected in epiphytic alga and vegetation samples collected from a reservoir with...was used because it was the most plentiful species in the study region. Treatment hydrilla, which supports epiphytic colonies of H. aetokthonos, was...August 2015 4 Extract preparation. A methanol extract was prepared from both the treatment and control hydrilla collections according to a

  13. Expression of a Clostridium perfringens genome-encoded putative N-acetylmuramoyl-L-alanine amidase as a potential antimicrobial to control the bacterium

    USDA-ARS?s Scientific Manuscript database

    Clostridium perfringens is a Gram-positive, spore-forming anaerobic bacterium that plays a substantial role in non-foodborne human, animal and avian diseases as well as human foodborne disease. Previously discovered C. perfringens bacteriophage lytic enzyme amino acid sequences were utilized to iden...

  14. Validation of the analytical procedure for the determination of the neurotoxin β-N-methylamino-L-alanine in complex environmental samples.

    PubMed

    Combes, Audrey; El Abdellaoui, Saïda; Sarazin, Cédric; Vial, Jérome; Mejean, Annick; Ploux, Olivier; Pichon, Valérie

    2013-04-10

    The neurotoxic l-2-amino-3-methylaminopropionic acid (BMAA) was hypothesized to be involved in sporadic cases of amyotrophic lateral sclerosis (ALS). Studies highlighting a possible implication of environmental factors in the incidence of sporadic ALS have become more numerous over recent years. Over the past years, the most widely used method for quantifying BMAA was based on the derivatization of this polar and basic molecule with a fluorescent compound (6-aminoquinolonyl-N-hydroxysuccinimidyl, 6-AQC). This derivatization allows the retention of the conjugate by reversed-phase liquid chromatography and its detection by fluorescence. Nevertheless, recent findings have shown that this method applied to complex samples may cause false positive responses. We therefore developed an analytical procedure for the determination of underivatized BMAA at trace level in complex environmental matrices (river water, cyanobacteria and biofilm) using solid-phase extraction (SPE) based on mixed mode sorbent to concentrate and clean up real samples. Analyzes were performed by hydrophilic interaction chromatography (HILIC) coupled to electrospray ionization and tandem mass spectrometry used in multiple reaction monitoring scan mode. Analytical procedures were validated for the different natural samples using the total error approach. BMAA can be quantified by these reliable and highly selective analytical methods in a range of only a few ng mL(-1) in river water and a few ng mg(-1) dry weight in cyanobacteria and biofilm matrices.

  15. Excess of L-Alanine in Amino Acids Synthesized in a Plasma Torch Generated by a Hypervelocity Meteorite Impact Reproduced in the Laboratory

    NASA Technical Reports Server (NTRS)

    Managadze, George G.; Engle, Michael H.; Getty, Stephanie A.; Wurz, Peter; Brinckerhoff, William B.; Shokolov, Anatoly; Sholin, Gennady; Terent'ev, Sergey A.; Chumikov, Alexander E.; Skalkin, Alexander S

    2016-01-01

    We present a laboratory reproduction of hypervelocity impacts of a carbon containing meteorite on a mineral substance representative of planetary surfaces. The physical conditions of the resulting impact plasma torch provide favorable conditions for abiogenic synthesis of protein amino acids: We identified glycine and alanine, and in smaller quantities serine, in the produced material. Moreover, we observe breaking of alanine mirror symmetry with L excess, which coincides with the bioorganic world. Therefore the selection of L-amino acids for the formation of proteins for living matter could have been the result from plasma processes occurring during the impact meteorites on the surface. This indicates that the plasma torch from meteorite impacts could play an important role in the formation of biomolecular homochirality. Thus, meteorite impacts possibly were the initial stage of this process and promoted conditions for the emergence of a living matter.

  16. Characterization of LytA-Like N-Acetylmuramoyl-l-Alanine Amidases from Two New Streptococcus mitis Bacteriophages Provides Insights into the Properties of the Major Pneumococcal Autolysin

    PubMed Central

    Romero, Patricia; López, Rubens; García, Ernesto

    2004-01-01

    Two new temperate bacteriophages exhibiting a Myoviridae (φB6) and a Siphoviridae (φHER) morphology have been isolated from Streptococcus mitis strains B6 and HER 1055, respectively, and partially characterized. The lytic phage genes were overexpressed in Escherichia coli, and their encoded proteins were purified. The lytAHER and lytAB6 genes are very similar (87% identity) and appeared to belong to the group of the so-called typical LytA amidases (atypical LytA displays a characteristic two-amino-acid deletion signature). although they exhibited several differential biochemical properties with respect to the pneumococcal LytA, e.g., they were inhibited in vitro by sodium deoxycholate and showed a more acidic pH for optimal activity. However, and in sharp contrast with the pneumococcal LytA, a short dialysis of LytAHER or LytAB6 resulted in reversible deconversion to the low-activity state (E-form) of the fully active phage amidases (C-form). Comparison of the amino acid sequences of LytAHER and LytAB6 with that of the pneumococcal amidase suggested that Val317 might be responsible for at least some of the peculiar properties of S. mitis phage enzymes. Site-directed mutagenesis that changed Val317 in the pneumococcal LytA amidase to a Thr residue (characteristic of LytAB6 and LytAHER) produced a fully active pneumococcal enzyme that differs from the parental one only in that the mutant amidase can reversibly recover the low-activity E-form upon dialysis. This is the first report showing that a single amino acid residue is involved in the conversion process of the major S. pneumoniae autolysin. Our results also showed that some lysogenic S. mitis strains possess a lytA-like gene, something that was previously thought to be exclusive to Streptococcus pneumoniae. Moreover, the newly discovered phage lysins constitute a missing link between the typical and atypical pneumococcal amidases known previously. PMID:15576771

  17. Excess of L-alanine in amino acids synthesized in a plasma torch generated by a hypervelocity meteorite impact reproduced in the laboratory

    NASA Astrophysics Data System (ADS)

    Managadze, George G.; Engel, Michael H.; Getty, Stephanie; Wurz, Peter; Brinckerhoff, William B.; Shokolov, Anatoly G.; Sholin, Gennady V.; Terent'ev, Sergey A.; Chumikov, Alexander E.; Skalkin, Alexander S.; Blank, Vladimir D.; Prokhorov, Vyacheslav M.; Managadze, Nina G.; Luchnikov, Konstantin A.

    2016-10-01

    We present a laboratory reproduction of hypervelocity impacts of a carbon containing meteorite on a mineral substance representative of planetary surfaces. The physical conditions of the resulting impact plasma torch provide favorable conditions for abiogenic synthesis of protein amino acids: We identified glycine and alanine, and in smaller quantities serine, in the produced material. Moreover, we observe breaking of alanine mirror symmetry with L excess, which coincides with the bioorganic world. Therefore the selection of L-amino acids for the formation of proteins for living matter could have been the result from plasma processes occurring during the impact meteorites on the surface. This indicates that the plasma torch from meteorite impacts could play an important role in the formation of biomolecular homochirality. Thus, meteorite impacts possibly were the initial stage of this process and promoted conditions for the emergence of a living matter.

  18. Recombinant Expression of a Genome-encoded N-acetylmuramoyl-L-alanine Amidase that Synergistically Lyses Listeria monocytogenes Biofilms with a Protease

    USDA-ARS?s Scientific Manuscript database

    Listeria monocytogenes plays a significant role in human food-borne disease caused by eating food contaminated with the bacterium and although incidence is low it is a leading cause of life-threatening, bacterial food-borne disease in humans. L. monocytogenes serotypes 1/2a and 4b can form mixed-cu...

  19. Structural analysis and mutant growth properties reveal distinctive enzymatic and cellular roles for the three major L-alanine transaminases of Escherichia coli.

    PubMed

    Peña-Soler, Esther; Fernandez, Francisco J; López-Estepa, Miguel; Garces, Fernando; Richardson, Andrew J; Quintana, Juan F; Rudd, Kenneth E; Coll, Miquel; Vega, M Cristina

    2014-01-01

    In order to maintain proper cellular function, the metabolism of the bacterial microbiota presents several mechanisms oriented to keep a correctly balanced amino acid pool. Central components of these mechanisms are enzymes with alanine transaminase activity, pyridoxal 5'-phosphate-dependent enzymes that interconvert alanine and pyruvate, thereby allowing the precise control of alanine and glutamate concentrations, two of the most abundant amino acids in the cellular amino acid pool. Here we report the 2.11-Å crystal structure of full-length AlaA from the model organism Escherichia coli, a major bacterial alanine aminotransferase, and compare its overall structure and active site composition with detailed atomic models of two other bacterial enzymes capable of catalyzing this reaction in vivo, AlaC and valine-pyruvate aminotransferase (AvtA). Apart from a narrow entry channel to the active site, a feature of this new crystal structure is the role of an active site loop that closes in upon binding of substrate-mimicking molecules, and which has only been previously reported in a plant enzyme. Comparison of the available structures indicates that beyond superficial differences, alanine aminotransferases of diverse phylogenetic origins share a universal reaction mechanism that depends on an array of highly conserved amino acid residues and is similarly regulated by various unrelated motifs. Despite this unifying mechanism and regulation, growth competition experiments demonstrate that AlaA, AlaC and AvtA are not freely exchangeable in vivo, suggesting that their functional repertoire is not completely redundant thus providing an explanation for their independent evolutionary conservation.

  20. Structure-based design of a new series of D-glutamic acid based inhibitors of bacterial UDP-N-acetylmuramoyl-L-alanine:D-glutamate ligase (MurD).

    PubMed

    Tomasić, Tihomir; Zidar, Nace; Sink, Roman; Kovac, Andreja; Blanot, Didier; Contreras-Martel, Carlos; Dessen, Andréa; Müller-Premru, Manica; Zega, Anamarija; Gobec, Stanislav; Kikelj, Danijel; Masic, Lucija Peterlin

    2011-07-14

    MurD ligase is one of the key enzymes participating in the intracellular steps of peptidoglycan biosynthesis and constitutes a viable target in the search for novel antibacterial drugs to combat bacterial drug-resistance. We have designed, synthesized, and evaluated a new series of D-glutamic acid-based Escherichia coli MurD inhibitors incorporating the 5-benzylidenethiazolidin-4-one scaffold. The crystal structure of 16 in the MurD active site has provided a good starting point for the design of structurally optimized inhibitors 73-75 endowed with improved MurD inhibitory potency (IC(50) between 3 and 7 μM). Inhibitors 74 and 75 showed weak activity against Gram-positive Staphylococcus aureus and Enterococcus faecalis. Compounds 73-75, with IC(50) values in the low micromolar range, represent the most potent D-Glu-based MurD inhibitors reported to date.

  1. Modified triglycine sulphate (TGS) single crystals for pyroelectric infrared detector applications

    NASA Technical Reports Server (NTRS)

    Banan, M.; Lal, R. B.; Batra, Ashok

    1992-01-01

    Effects of caesium and cerium, L-alanine, and caesium plus L-alanine impurities on ferroelectric and pyroelectric properties of TGS crystals are investigated. Dielectric constant and loss, pyroelectric coefficient, spontaneous polarization, and coercive field measurements of these modified crystals, as a function of temperature, are reported. Caesium and cerium did not affect the electrical properties of TGS crystals significantly, whereas L-alanine- and, especially, Cs + L-alanine-doped TGS crystals exhibited promising improvements in pyroelectric properties, up to 48 C, as compared to pure TGS crystals.

  2. Studies on Escherichia coli enzymes involved in the synthesis of uridine diphosphate-N-acetyl-muramyl-pentapeptide.

    PubMed

    Lugtenberg, E J

    1972-04-01

    The specific activities of l-alanine:d-alanine racemase, d-alanine:d-alanine ligase, and the l-alanine, d-glutamic acid, meso-diaminopimelic acid, and d-alanyl-d-alanine adding enzymes were followed during growth of Escherichia coli. The specific activities were nearly independent of the growth phase. d-Alanine:d-alanine ligase was inhibited by d-alanyl-d-alanine, d-cycloserine, glycine, and glycyl-glycine. l-Alanine:d-alanine racemase was found to be sensitive to d-cycloserine, glycine, and glycyl-glycine. The l-alanine adding enzyme was inhibited by glycine and glycyl-glycine.

  3. Modified triglycine sulphate (TGS) single crystals for pyroelectric infrared detector applications

    NASA Technical Reports Server (NTRS)

    Banan, M.; Lal, R. B.; Batra, Ashok

    1992-01-01

    Effects of caesium and cerium, L-alanine, and caesium plus L-alanine impurities on ferroelectric and pyroelectric properties of TGS crystals are investigated. Dielectric constant and loss, pyroelectric coefficient, spontaneous polarization, and coercive field measurements of these modified crystals, as a function of temperature, are reported. Caesium and cerium did not affect the electrical properties of TGS crystals significantly, whereas L-alanine- and, especially, Cs + L-alanine-doped TGS crystals exhibited promising improvements in pyroelectric properties, up to 48 C, as compared to pure TGS crystals.

  4. Man-Materiel Systems. Questionnaire and Interview Design (Subjective Testing Techniques). Volume I

    DTIC Science & Technology

    1975-07-25

    paragraph H-10, appendix H). o 4-19 ’*~ mS ’ ■ » I TECOM Pan 602-1. Vol I (5) Method» of Ranking. There are several methods of wording...Background of participants 3-4 Basic multipla choica quastion 4-12 Bias r • • • 5-3. 9-2. Laading quaations 5-3. L adad words 5-4...quaationnaira daalgn 2-1 Mathoda of ranking 4-20 Mlddla catagorlaa 4-9. 4-31 Multipla cholca quaatlona 4-12 Basic aultipla cholca 4-12 Exaaplaa

  5. Software Process Development and Enactment: Concepts and Definitions

    DTIC Science & Technology

    1992-09-01

    desirable to simultaneously plan multipla Instantlations to reduce the amount of planning and improve the efficiency of Instantlation, Evolution: The act of...refinement of the process definition before the responsibility to enact is transferred. For exampe, Mr. Jones may delegate his approval authority to Ms . Doe

  6. An Analysis of the Computer System Chargeback Concept in the Naval Industrial Fund Environment.

    DTIC Science & Technology

    1983-06-01

    resource is a single, s-raightforward economic cn, in contrast to multipla , pa-rtially noneconomic goals for other staff ac-ivities. Howev-_, this...at -the- same ti- ms the NIF act ivit-y and its parent command are preparing a II budget (which conta-r~s the anticipated work to be performed for

  7. National Dam Safety Program. Lake Thunderhead Dam (MO 10007), Grand - Chariton Basin, Putnam County, Missouri. Phase I Inspection Report.

    DTIC Science & Technology

    1980-05-01

    1965 by Howard Construction Co., Sedalia, Mo. According to Ms . Quigley, Unionville City Clerk, this project was financed by a loan from the U.S.D.A...to accomplish the d;I=ernz rcquired it will be neoessary to use a multipla sta4e well point instaflsto=. where separate rows of well "oints are drien

  8. An Experimental Brain Missile Wound: Ascertaining Pathophysiology and Evaluating Treatments to Lower Mortality and Morbidity

    DTIC Science & Technology

    1991-06-04

    a soldier might get a brain wound as well as another wound (eg femoral artery) leading to significant blood loss. Multipla fragment wounds are...cerebral circulation in health and disease. Circ Res 34:749-760, 1974 91. Lassen NA, Christensen MS : Physiology of cerebral blood flow. Br J Anesthesiol 48

  9. Substrate Specificity of the Aspartate:Alanine Antiporter (AspT) of Tetragenococcus halophilus in Reconstituted Liposomes*

    PubMed Central

    Sasahara, Ayako; Nanatani, Kei; Enomoto, Masaru; Kuwahara, Shigefumi; Abe, Keietsu

    2011-01-01

    The aspartate:alanine antiporter (AspT) of the lactic acid bacterium Tetragenococcus halophilus is a member of the aspartate:alanine exchanger (AAEx) transporter family. T. halophilus AspT catalyzes the electrogenic exchange of l-aspartate1− with l-alanine0. Although physiological functions of AspT were well studied, l-aspartate1−:l-alanine0 antiport mechanisms are still unsolved. Here we report that the binding sites of l-aspartate and l-alanine are independently present in AspT by means of the kinetic studies. We purified His6-tagged T. halophilus AspT and characterized its kinetic properties when reconstituted in liposomes (Km = 0.35 ± 0.03 mm for l-aspartate, Km = 0.098 ± 0 mm for d-aspartate, Km = 26 ± 2 mm for l-alanine, Km = 3.3 ± 0.2 mm for d-alanine). Competitive inhibition by various amino acids of l-aspartate or l-alanine in self-exchange reactions revealed that l-cysteine selectively inhibited l-aspartate self-exchange but only weakly inhibited l-alanine self-exchange. Additionally, l-serine selectively inhibited l-alanine self-exchange but barely inhibited l-aspartate self-exchange. The aspartate analogs l-cysteine sulfinic acid, l-cysteic acid, and d-cysteic acid competitively and strongly inhibited l-aspartate self-exchange compared with l-alanine self-exchange. Taken together, these kinetic data suggest that the putative binding sites of l-aspartate and l-alanine are independently located in the substrate translocation pathway of AspT. PMID:21719707

  10. Substrate specificity of the aspartate:alanine antiporter (AspT) of Tetragenococcus halophilus in reconstituted liposomes.

    PubMed

    Sasahara, Ayako; Nanatani, Kei; Enomoto, Masaru; Kuwahara, Shigefumi; Abe, Keietsu

    2011-08-19

    The aspartate:alanine antiporter (AspT) of the lactic acid bacterium Tetragenococcus halophilus is a member of the aspartate:alanine exchanger (AAEx) transporter family. T. halophilus AspT catalyzes the electrogenic exchange of L-aspartate(1-) with L-alanine(0). Although physiological functions of AspT were well studied, L-aspartate(1-):L-alanine(0) antiport mechanisms are still unsolved. Here we report that the binding sites of L-aspartate and L-alanine are independently present in AspT by means of the kinetic studies. We purified His(6)-tagged T. halophilus AspT and characterized its kinetic properties when reconstituted in liposomes (K(m) = 0.35 ± 0.03 mm for L-aspartate, K(m) = 0.098 ± 0 mm for D-aspartate, K(m) = 26 ± 2 mm for L-alanine, K(m) = 3.3 ± 0.2 mm for D-alanine). Competitive inhibition by various amino acids of L-aspartate or L-alanine in self-exchange reactions revealed that L-cysteine selectively inhibited L-aspartate self-exchange but only weakly inhibited L-alanine self-exchange. Additionally, L-serine selectively inhibited L-alanine self-exchange but barely inhibited L-aspartate self-exchange. The aspartate analogs L-cysteine sulfinic acid, L-cysteic acid, and D-cysteic acid competitively and strongly inhibited L-aspartate self-exchange compared with L-alanine self-exchange. Taken together, these kinetic data suggest that the putative binding sites of L-aspartate and L-alanine are independently located in the substrate translocation pathway of AspT.

  11. Synthesis of isotopically labeled versions of L-MTP-PE (mifamurtide) and MDP.

    PubMed

    Li, Yuexian; Plesescu, Mihaela; Prakash, Shimoga R

    2013-01-01

    L-MTP-PE (1), an immunomodulator and its metabolite MDP (4) were synthesized from labeled l-alanine and its protected derivative, respectively. The key intermediate product for the labeled L-MTP-PE synthesis, [(13) C3 ,D4 ]-alanyl-cephalin (2A), was synthesized from [(13) C3 ,D4 ]-l-alanine (3A) in three steps. The key intermediate product for labeled MDP synthesis, amine 11, was prepared from [(13) C3 ,(15) N]-Boc-l-alanine (5A) in two steps.

  12. Alanine increases blood pressure during hypotension

    NASA Technical Reports Server (NTRS)

    Conlay, L. A.; Maher, T. J.; Wurtman, R. J.

    1990-01-01

    The effect of L-alanine administration on blood pressure (BP) during haemorrhagic shock was investigated using anesthetized rats whose left carotid arteries were cannulated for BP measurement, blood removal, and drug administration. It was found that L-alanine, in doses of 10, 25, 50, 100, and 200 mg/kg, increased the systolic BP of hypotensive rats by 38 to 80 percent (while 100 mg/kg pyruvate increased BP by only 9.4 mmhg, not significantly different from saline). The results suggest that L-alanine might influence cardiovascular function.

  13. Alanine increases blood pressure during hypotension

    NASA Technical Reports Server (NTRS)

    Conlay, L. A.; Maher, T. J.; Wurtman, R. J.

    1990-01-01

    The effect of L-alanine administration on blood pressure (BP) during haemorrhagic shock was investigated using anesthetized rats whose left carotid arteries were cannulated for BP measurement, blood removal, and drug administration. It was found that L-alanine, in doses of 10, 25, 50, 100, and 200 mg/kg, increased the systolic BP of hypotensive rats by 38 to 80 percent (while 100 mg/kg pyruvate increased BP by only 9.4 mmhg, not significantly different from saline). The results suggest that L-alanine might influence cardiovascular function.

  14. Encapsulation of Bacterial Spores in Nanoorganized Polyelectrolyte Shells (Postprint)

    DTIC Science & Technology

    2009-05-27

    2,6-Pyridine dicarboxylic acid (DPA, 99%) and terbium chloride hexahydrate (TbCl3, 99.9%) were also pur- chased from Sigma-Aldrich. L-Alanine (L-Ala...germination induction by L-alanine exposure. DPArelease ismonitoredover timebymeasuring the fluorescence emission of DPA when bound to terbium ions...the onset of germination within the population. Following the addition of a soluble germinant, the fluorescent DPA- terbium complex was detected almost

  15. Regulation of the ald gene encoding alanine dehydrogenase by AldR in Mycobacterium smegmatis.

    PubMed

    Jeong, Ji-A; Baek, Eun-Young; Kim, Si Wouk; Choi, Jong-Soon; Oh, Jeong-Il

    2013-08-01

    The regulatory gene aldR was identified 95 bp upstream of the ald gene encoding L-alanine dehydrogenase in Mycobacterium smegmatis. The AldR protein shows sequence similarity to the regulatory proteins of the Lrp/AsnC family. Using an aldR deletion mutant, we demonstrated that AldR serves as both activator and repressor for the regulation of ald gene expression, depending on the presence or absence of L-alanine. The purified AldR protein exists as a homodimer in the absence of L-alanine, while it adopts the quaternary structure of a homohexamer in the presence of L-alanine. The binding affinity of AldR for the ald control region was shown to be increased significantly by L-alanine. Two AldR binding sites (O1 and O2) with the consensus sequence GA-N₂-ATC-N₂-TC and one putative AldR binding site with the sequence GA-N₂-GTT-N₂-TC were identified upstream of the ald gene. Alanine and cysteine were demonstrated to be the effector molecules directly involved in the induction of ald expression. The cellular level of L-alanine was shown to be increased in M. smegmatis cells grown under hypoxic conditions, and the hypoxic induction of ald expression appears to be mediated by AldR, which senses the intracellular level of alanine.

  16. MultipLa--a tool for the combined overall estimation of various types of manual handling tasks.

    PubMed

    Karlheinz, Schaub; Max, Bierwirth; Michaela, Kugler; Ralph, Bruder

    2012-01-01

    In the 1990ies the German Federal Institute for Occupational Safety and Health (FIOSH) published "Key Indicator Methods" (KIM) for the evaluation of manual material handling tasks. These methods served as a national German implementation of the EU Manual Handling Directive (90/269/EEC). These methods allow the evaluation of individual handling tasks like lifting or pushing. KIM tools do not allow evaluating complex handling tasks like a combined lifting and pushing task. With respect to the needs at shop floor level (e.g. logistics), MultipLa tries to bridge that gap by means of an EXCEL based worksheet using the KIM philosophy. In the past several algorithms for a risk assessment had been developed. At the moment MultipLa is in a test phase at several automotive OEMs.

  17. Mathematical Model of Metabolism and Electrophysiology of Amino Acid and Glucose Stimulated Insulin Secretion: In Vitro Validation Using a β-Cell Line

    PubMed Central

    Salvucci, Manuela; Neufeld, Zoltan; Newsholme, Philip

    2013-01-01

    We integrated biological experimental data with mathematical modelling to gain insights into the role played by L-alanine in amino acid-stimulated insulin secretion (AASIS) and in D-glucose-stimulated insulin secretion (GSIS), details important to the understanding of complex β-cell metabolic coupling relationships. We present an ordinary differential equations (ODEs) based simplified kinetic model of core metabolic processes leading to ATP production (glycolysis, TCA cycle, L-alanine-specific reactions, respiratory chain, ATPase and proton leak) and Ca2+ handling (essential channels and pumps in the plasma membrane) in pancreatic β-cells and relate these to insulin secretion. Experimental work was performed using a clonal rat insulin-secreting cell line (BRIN-BD11) to measure the consumption or production of a range of important biochemical parameters (D-glucose, L-alanine, ATP, insulin secretion) and Ca2+ levels. These measurements were then used to validate the theoretical model and fine-tune the parameters. Mathematical modelling was used to predict L-lactate and L-glutamate concentrations following D-glucose and/or L-alanine challenge and Ca2+ levels upon stimulation with a non metabolizable L-alanine analogue. Experimental data and mathematical model simulations combined suggest that L-alanine produces a potent insulinotropic effect via both a stimulatory impact on β-cell metabolism and as a direct result of the membrane depolarization due to Ca2+ influx triggered by L-alanine/Na+ co-transport. Our simulations indicate that both high intracellular ATP and Ca2+ concentrations are required in order to develop full insulin secretory responses. The model confirmed that K+ATP channel independent mechanisms of stimulation of intracellular Ca2+ levels, via generation of mitochondrial coupling messengers, are essential for promotion of the full and sustained insulin secretion response in β-cells. PMID:23520444

  18. The Shock and Vibration Digest. Volume 14, Number 8

    DTIC Science & Technology

    1982-08-01

    MS 38677, J. Energy Resources Tech., Trans. ASME, IM (1). PP 47-52 (Mar 1982) 4 figs, 7 refs Key Words: Offshore structures, Wave forces, Submerged...hipt ara pratantad. A ttatittical mathod of multipla linear regret- tion wet utad for data prooattlng. Calculated and meatured ratuitt ware...Waterways Experiment Station, Vicksburg, MS , Rept. No. WES-MP-C-77-11-3, 36 pp (Nov 1981) AD-A109 814 Key Wordi: Concrete», Nondettructlve tatti

  19. Better Management of Private Pension Plan Data Can Reduce Costs and Improve ERISA Administration.

    DTIC Science & Technology

    1981-10-19

    benefit payable to any partlcioe nt to be o rsd" . . U.Sl. M091 I’M"W~IS Ms 31-0nosarl is51632 67 APPENDIX V APPENDIX V 5500-K Annual Return/Report of...c) 0 Multiemployer plan (d) [] Multipla -emplayer-collectively-bargained plan (e) E] Multiple-employer plan (other) 5 (a) (I) Mam of plan 10

  20. Aircraft Crash Survival Design Guide. Volume 1. Design Criteria and Checklists

    DTIC Science & Technology

    1989-12-01

    50th 99 percentile dummy (Reference 36) it, Test 1 and a clad 95th-percentile dummy in Test 2. Dynamic testing of multipla -occupant seats shnuld be...Idiyn nir-rf l ATFl rAr T nflrTn Rubbins, D. H.., et al, uEVELUOI’IIE I Ali,’u TEa , I ING ur ilIURlMIU JLLMI nLJI IN, SYST[ MS , Highway Safety Research

  1. Effects of Competition and Mode of Fire on Physiological Responses, Psychological Stress Reactions, and Shooting Performance

    DTIC Science & Technology

    1991-07-01

    during baseline day and record-fire day. 113 Table S Analysis of Variance of Mean Heart Rates Source $$ df MS F p Total 3089.334 23 Between 1204.334 11...Sensation aaakin92 Resond Phe a•t•M1 level .A ArLouna£l. Hillsdale, NJ: Erlbaum. Zuckerman, M., & Lubin, B. (1965). Manal Igt£rthe Multipla Affect Adat

  2. Nonlinear Analysis of Frame Structures Subjected to Blast Overpressures

    DTIC Science & Technology

    1977-05-01

    Ms . Marie Mitchell of Aumann & Whitney for technical typing and to Messrs. V. Kald, A. Maggio and F. Wendling for preparing the art- work contained in...commnonly referred to as " ms points"). Consequently, the model has a limited number of the strctue’snormal modes of vibration. The nature of these...exterior members, as shown in Figure 14b. In general, multipla intermediate mass points are utilized as a more accurate representation of the local

  3. Oxidative Activation of Bacillus cereus Spores

    PubMed Central

    Cochran, Stuart A.; Ordal, Z. John

    1973-01-01

    A study was made of the activation of Bacillus cereus strain T spores by using the oxidizing agent sodium perborate. The degree of activation was measured with constant germination conditions by using L-alanine, inosine, adenosine, and L-alanine plus adenosine as germination stimulants. The germinal response following the various treatments was compared with the responses obtained with heat activation. It was concluded that the optimal time for activation with 30 mM sodium perborate at room temperature was about 4 hr. If the exposure time was greatly extended, the spores would germinate spontaneously. When the perborate treatment followed heat activation, the germinal response to L-alanine was stimulated, to inosine retarded and without apparent effect for adenosine or L-alanine plus adenosine. Results of experiments designed to demonstrate deactivation by slow oxidation showed that spores activated with sodium perborate were not deactivated by slow oxidation, whereas those activated by heat were. A deactivation study using mercaptoethanol as the deactivation agent showed that both methods of activation could be deactivated after a 24-hr exposure, but this deactivation was reversible by extending the exposure to mercaptoethanol. The results of heat-sensitivity studies revealed that about 70% of the sodium perborate-activated spores were heat sensitive after 60 min in a germination menstruum of L-alanine plus adenosine, whereas similarly treated heat-activated and nonactivated spores were about 99.99% heat sensitive, respectively. PMID:4632848

  4. Involvement of alanine racemase in germination of Bacillus cereus spores lacking an intact exosporium.

    PubMed

    Venir, Elena; Del Torre, Manuela; Cunsolo, Vincenzo; Saletti, Rosaria; Musetti, Rita; Stecchini, Mara Lucia

    2014-02-01

    The L-alanine mediated germination of food isolated Bacillus cereus DSA 1 spores, which lacked an intact exosporium, increased in the presence of D-cycloserine (DCS), which is an alanine racemase (Alr) inhibitor, reflecting the activity of the Alr enzyme, capable of converting L-alanine to the germination inhibitor D-alanine. Proteomic analysis of the alkaline extracts of the spore proteins, which include exosporium and coat proteins, confirmed that Alr was present in the B. cereus DSA 1 spores and matched to that encoded by B. cereus ATCC 14579, whose spore germination was strongly affected by the block of conversion of L- to D-alanine. Unlike ATCC 14579 spores, L-alanine germination of B. cereus DSA 1 spores was not affected by the preincubation with DCS, suggesting a lack of restriction in the reactant accessibility.

  5. Chemical shift tensor determination using magnetically oriented microcrystal array (MOMA): 13C solid-state CP NMR without MAS

    NASA Astrophysics Data System (ADS)

    Kusumi, R.; Kimura, F.; Song, G.; Kimura, T.

    2012-10-01

    Chemical shift tensors for the carboxyl and methyl carbons of L-alanine crystals were determined using a magnetically oriented microcrystal array (MOMA) prepared from a microcrystalline powder sample of L-alanine. A MOMA is a single-crystal-like composite in which microcrystals are aligned three-dimensionally in a matrix resin. The single-crystal rotation method was applied to the MOMA to determine the principal values and axes of the chemical shift tensors. The result showed good agreement with the literature data for the single crystal of L-alanine. This demonstrates that the present technique is a powerful tool for determining the chemical shift tensor of a crystal from a microcrystal powder sample.

  6. Functional Characterization of a Melittin Analog Containing a Non-natural Tryptophan Analog

    PubMed Central

    Gosavi, Pallavi M.; Moroz, Yurii S.; Angevine, Christopher E.; Chavis, Amy E.; Reiner, Joseph E.; Korendovych, Ivan V.; Caputo, Gregory A.

    2015-01-01

    Tryptophan (Trp) is a naturally occurring amino acid, which exhibits fluorescence emission properties that are dependent on the polarity of the local environment around the Trp side chain. However, this sensitivity also complicates interpretation of fluorescence emission data. A non-natural analogue of tryptophan, β-(1-azulenyl)-L-alanine, exhibits fluorescence insensitive to local solvent polarity and does not impact the structure or characteristics of several peptides examined. In this study we investigated the effect of replacing Trp with β-(1-azulenyl)-L-alanine in the well-known bee-venom peptide melittin. This peptide provides a model framework for investigating the impact of replacing Trp with β-(1-azulenyl)-L- alanine in a functional peptide system that undergoes significant shifts in Trp fluorescence emission upon binding to lipid bilayers. Microbiological methods including assessment of the antimicrobial activity by minimal inhibitory concentration (MIC) assays and bacterial membrane permeability assays indicated little difference between the Trp and the β-(1-azulenyl)-L-alanine-substituted versions of melittin. Circular dichroism spectroscopy showed both that peptides adopted the expected α-helical structures when bound to phospholipid bilayers and electrophysiological analysis indicated that both created membrane disruptions leading to significant conductance increases across model membranes. Both peptides exhibited a marked protection of the respective fluorophores when bound to bilayers indicating a similar membrane-bound topology. As expected, while fluorescence quenching and CD indicate the peptides are stably bound to lipid vesicles, the peptide containing β-(1-azulenyl)-L-alanine exhibited no fluorescence emission shift upon binding while the natural Trp exhibited >10 nm shift in emission spectrum barycenter. Taken together, the β-(1-azulenyl)-L-alanine can serve as a solvent insensitive alternative to Trp that does not have significant

  7. Glutamine and alanine-induced differential expression of intracellular IL-6, IL-8, and TNF-α in LPS-stimulated monocytes in human whole-blood.

    PubMed

    Raspé, C; Czeslick, E; Weimann, A; Schinke, C; Leimert, A; Kellner, P; Simm, A; Bucher, M; Sablotzki, A

    2013-04-01

    To investigate the effects of the commonly-used immunomodulators l-glutamine, l-alanine, and the combination of both l-alanyl-l-glutamine (Dipeptamin(®)) on intracellular expression of IL-6, IL-8, and TNF-α during endotoxemia, lipopolysaccharide (LPS)-stimulated human monocytes in a whole blood system were investigated by flow cytometry. Whole blood of twenty-seven healthy volunteers was stimulated with LPS and incubated with three different amino acid solutions (1. l-glutamine, 2. l-alanine, 3. l-alanyl-l-glutamine, each concentration 2 mM, 5 mM, incubation time 3 h). CD14(+) monocytes were phenotyped in whole-blood and intracellular expression of cytokines was assessed by flow cytometry. Our investigations showed for the first time in whole blood probes, imitating best physiologically present cellular interactions, that l-glutamine caused a dose-independent inhibitory effect on IL-6 and TNF-α production in human monocytes stimulated with LPS. However, l-alanine had contrary effects on IL-6 expression, significantly upregulating expression of IL-6 in LPS-treated monocytes. The impact of l-alanine on the expression of TNF-α was comparable with glutamine. Neither amino acid was able to affect IL-8 production in LPS-stimulated monocytes. The combination of both did not influence significantly IL-6 and IL-8 expression in monocytes during endotoxemia, however strongly reduced TNF-α production. For the regulation of TNF-α, l-glutamine, l-alanine and the combination of both show a congruent and exponentiated downregulating effect during endotoxemia, for the modulation of IL-6, l-glutamine and l-alanine featured opposite regulation leading to a canceling impact of each other when recombining both amino acids.

  8. Role of the gerI Operon of Bacillus cereus 569 in the Response of Spores to Germinants

    PubMed Central

    Clements, Mark O.; Moir, Anne

    1998-01-01

    Bacillus cereus 569 (ATCC 10876) germinates in response to inosine or to l-alanine, but the most rapid germination response is elicited by a combination of these germinants. Mutants defective in their germination response to either inosine or to l-alanine were isolated after Tn917-LTV1 mutagenesis and enrichment procedures; one class of mutant could not germinate in response to inosine as a sole germinant but still germinated in response to l-alanine, although at a reduced rate; another mutant germinated normally in response to inosine but was slowed in its germination response to l-alanine. These mutants demonstrated that at least two signal response pathways are involved in the triggering of germination. Stimulation of germination in l-alanine by limiting concentrations of inosine and stimulation of germination in inosine by low concentrations of l-alanine were still detectable in these mutants, suggesting that such stimulation is not dependent on complete functionality of both these germination loci. Two transposon insertions that affected inosine germination were found to be located 2.2 kb apart on the chromosome. This region was cloned and sequenced, revealing an operon of three open reading frames homologous to those in the gerA and related operons of Bacillus subtilis. The individual genes of this gerI operon have been named gerIA, gerIB, and gerIC. The GerIA protein is predicted to possess an unusually long, charged, N-terminal domain containing nine tandem copies of a 13-amino-acid glutamine- and serine-rich sequence. PMID:9852021

  9. EFFECT OF SPORULATION MEDIUM ON HEAT RESISTANCE, CHEMICAL COMPOSITION, AND GERMINATION OF BACILLUS MEGATERIUM SPORES1

    PubMed Central

    Levinson, Hillel S.; Hyatt, Mildred T.

    1964-01-01

    Levinson, Hillel S. (U.S. Army Natick Laboratories, Natick, Mass.), and Mildred T. Hyatt. Effect of sporulation medium on heat resistance, chemical composition, and germination of Bacillus megaterium spores. J. Bacteriol. 87:876–886. 1964.—Bacillus megaterium spores, grown on variously supplemented media, had varying concentrations of P, Ca, Mn, or dipicolinic acid. Supplementation with CaCl2 yielded spores with increased heat resistance; addition of l-glutamate, l-proline, or increase of the phosphate concentration yielded spores with reduced heat resistance. Germination characteristics depended on both the sporulation medium and the germinant (glucose, l-alanine, l-leucine, or KNO3); pronounced differences were demonstrable with glucose and l-alanine, which trigger germination via different metabolic pathways. An increase in CaCl2 during sporulation yielded spores with increased germination in glucose but not in l-alanine. Germination in l-alanine was optimal with spores produced on media containing 0.1 mm MnCl2, but germination of such spores was minimal in glucose. An increase in the sporulation medium phosphate decreased the initial germination rate in glucose, but not in l-alanine. Spores produced in CaCl2-supplemented media had increased heat-activation requirements (increased dormancy) for germination induced by l-alanine, and decreased heat-shock requirements for glucose-induced germination. An increase of sporulation phosphate yielded spores with reduced dormancy for germination induced by l-alanine, but with unchanged dormancy on the other germinants. Spores produced with added l-glutamate had reduced dormancy for glucose-induced germination, and increased dormancy for germination induced by l-alanine. Addition of CaCl2 or l-glutamate to the sporulation medium yielded spores with increased sensitivity to “ionic germination” (with KI). Spores from synthetic medium were incapacitated for full postgerminative development, as shown by repression of

  10. Murine Macrophages Kill the Vegetative Form of Bacillus anthracis

    DTIC Science & Technology

    2005-08-18

    inhibitor of the germination of B. anthracis and Bacillus cereus spores. It converts L-alanine to D-alanine, an isomer that is not recognized by...nation of Bacillus cereus spores in response to L-alanine and to inosine: the roles of gerL and gerQ operons. Microbiology 148:2089–2095. 5. Dixon, T...anthracis. J. Appl. Bacteriol. 62:269–273. 32. Todd, S. J., A. J. Moir, M. J. Johnson, and A. Moir. 2003. Genes of Bacillus cereus and Bacillus anthracis

  11. Binding region of alanopine dehydrogenase predicted by unbiased molecular dynamics simulations of ligand diffusion.

    PubMed

    Gohlke, Holger; Hergert, Ulrike; Meyer, Tatu; Mulnaes, Daniel; Grieshaber, Manfred K; Smits, Sander H J; Schmitt, Lutz

    2013-10-28

    Opine dehydrogenases catalyze the reductive condensation of pyruvate with L-amino acids. Biochemical characterization of alanopine dehydrogenase from Arenicola marina revealed that this enzyme is highly specific for L-alanine. Unbiased molecular dynamics simulations with a homology model of alanopine dehydrogenase captured the binding of L-alanine diffusing from solvent to a putative binding region near a distinct helix-kink-helix motif. These results and sequence comparisons reveal how mutations and insertions within this motif dictate the L-amino acid specificity.

  12. Inhibition of small-intestinal sugar and amino acid transport by the enterotoxin of Shigella dysenteriae I.

    PubMed

    Binder, H J; Whiting, D S

    1977-05-01

    The enterotoxin of Shigella dysenteriae I produces fluid and electrolyte secretion in the rabbit ileum. These present studies were designed to evaluate nonelectrolyte transport in rabbit ileal mucosa exposed to Shigella enterotoxin. Both 10 mM galactose and 5 mM L-alanine absorptions were significantly impaired in enterotoxin-exposed ileal mucosa compared with control mucosa. L-Alanine influx was not imparied in two other secretory processes: that induced by cholera enterotoxin and hyperosmolarity. These studies provide evidence that both surgar and amino acid absorptions are diminished in the small intestine by the enterotoxin of S. dysenteriae I.

  13. Inhibition of small-intestinal sugar and amino acid transport by the enterotoxin of Shigella dysenteriae I.

    PubMed Central

    Binder, H J; Whiting, D S

    1977-01-01

    The enterotoxin of Shigella dysenteriae I produces fluid and electrolyte secretion in the rabbit ileum. These present studies were designed to evaluate nonelectrolyte transport in rabbit ileal mucosa exposed to Shigella enterotoxin. Both 10 mM galactose and 5 mM L-alanine absorptions were significantly impaired in enterotoxin-exposed ileal mucosa compared with control mucosa. L-Alanine influx was not imparied in two other secretory processes: that induced by cholera enterotoxin and hyperosmolarity. These studies provide evidence that both surgar and amino acid absorptions are diminished in the small intestine by the enterotoxin of S. dysenteriae I. PMID:324910

  14. Characterization and properties of an LL-oligopeptidase from sporulating cells of Bacillus sphaericus.

    PubMed Central

    Vacheron, M J; Guinand, M; Michel, G

    1981-01-01

    An LL-oligopeptidase was characterized in the cell cytoplasm of sporulating Bacillus sphaericus 9602. Its activity showed a threefold increase throughout sporulation. The enzyme has lytic activity on various LL-dipeptides, especially on dipeptides with N-terminal L-alanine. Lytic activity was also found on some tripeptides and larger peptides which contain the sequence L-Ala-L-Ala. The role of this oligopeptidase in relation to sporulation may be to supply the cell with L-alanine for the biosynthesis of the peptide chains of the spore cortex. PMID:7007343

  15. Unusual substrate specificity of the peptidoglycan MurE ligase from Erysipelothrix rhusiopathiae.

    PubMed

    Patin, Delphine; Turk, Samo; Barreteau, Hélène; Mainardi, Jean-Luc; Arthur, Michel; Gobec, Stanislav; Mengin-Lecreulx, Dominique; Blanot, Didier

    2016-02-01

    Erysipelothrix rhusiopathiae is a Gram-positive bacterium pathogenic to many species of birds and mammals, including humans. The main feature of its peptidoglycan is the presence of l-alanine at position 3 of the peptide stem. In the present work, we cloned the murE gene from E. rhusiopathiae and purified the corresponding protein as His6-tagged form. Enzymatic assays showed that E. rhusiopathiae MurE was indeed an l-alanine-adding enzyme. Surprisingly, it was also able, although to a lesser extent, to add meso-diaminopimelic acid, the amino acid found at position 3 in many Gram-negative bacteria, Bacilli and Mycobacteria. Sequence alignment of MurE enzymes from E. rhusiopathiae and Escherichia coli revealed that the DNPR motif that is characteristic of meso-diaminopimelate-adding enzymes was replaced by HDNR. The role of the latter motif in the interaction with l-alanine and meso-diaminopimelic acid was demonstrated by site-directed mutagenesis experiments and the construction of a homology model. The overexpression of the E. rhusiopathiae murE gene in E. coli resulted in the incorporation of l-alanine at position 3 of the peptide part of peptidoglycan.

  16. Electron Spin Relaxation in Irradiated Solids.

    DTIC Science & Technology

    1996-03-01

    the development and use of ELDOR techniques to study the spectral diffusion in irradiated L-alanine and other irradiated organic solids. Pulsed STELDOR...and pulsed two-frequency ELDOR methods were developed and the details of the implementation is reported. The assignment of relaxation times that gave

  17. Amino acid uptake by liver of genetically obese Zucker rats.

    PubMed Central

    Ruiz, B; Felipe, A; Casado, J; Pastor-Anglada, M

    1991-01-01

    Alanine and glutamine uptake by the liver of 50-52-day-old genetically obese Zucker rats and their lean littermates has been studied. The net uptake in vivo of L-alanine is 2-fold higher in the obese animals. No significant change in L-glutamine net balance was found. We also studied the Na(+)-dependent uptake of L-alanine and L-glutamine into plasma-membrane vesicles isolated from either obese- or lean-rat livers. Vmax. values of both L-alanine and L-glutamine transport were 2-fold higher in those preparations from obese rats. No change in Km was observed. As suggested by inhibition studies, this seemed to be mediated by an enhancement of the activities of systems A, ASC and N. We conclude that the liver of the obese Zucker rat is extremely efficient in taking up neutral amino acids from the afferent blood, which results in an enhanced net uptake of L-alanine in vivo. The changes in transport activities at the plasma-membrane level might contribute to increase amino acid disposal by liver, probably for lipogenic purposes, as recently reported by Terrettaz & Jeanrenaud [Biochem. J. (1990) 270, 803-807]. PMID:1684102

  18. Synthesis, characterization, and biocompatible properties of alanine-grafted chitosan copolymers.

    PubMed

    Park, Gyu Han; Kang, Min-Sil; Knowles, Jonathan C; Gong, Myoung-Seon

    2016-04-01

    In order to overcome major problems regarding the lack of affinity to solvents and limited reactivity of the free amines of chitosan, introduction of appropriate spacer arms having terminal amine function is considered of interest. L-Alanine-N-carboxyanhydride was grafted onto chitosan via anionic ring-opening polymerization. The chemical and structural characterizations of L-alanine-grafted chitosan (Ala-g-Cts) were confirmed through Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy ((1)H NMR). In addition, the viscoelastic properties of Ala-g-Cts were examined by means of a rotational viscometer, and thermal analysis was carried out with a thermogravimetric analyzer and differential scanning calorimetry. Morphological changes in the chitosan L-alanine moiety were determined by x-ray diffraction. To determine the feasibility of using these films as biomedical materials, we investigated the effects of their L-alanine content on physical and mechanical properties. The biodegradation results of crosslinked Ala-g-Cts films were evaluated in phosphate-buffered solution containing lysozyme at 37℃. Proliferation of MC3T3-E1 cells on crosslinked Ala-g-Cts films was also investigated with use of the CCK-8 assay.

  19. Application of In Vivo Induced Antigen Technology (IVIAT) to Bacillus anthracis

    PubMed Central

    Rollins, Sean M.; Peppercorn, Amanda; Young, John S.; Drysdale, Melissa; Baresch, Andrea; Bikowski, Margaret V.; Ashford, David A.; Quinn, Conrad P.; Handfield, Martin; Hillman, Jeffrey D.; Lyons, C. Rick; Koehler, Theresa M.; Calderwood, Stephen B.; Ryan, Edward T.

    2008-01-01

    In vivo induced antigen technology (IVIAT) is an immuno-screening technique that identifies bacterial antigens expressed during infection and not during standard in vitro culturing conditions. We applied IVIAT to Bacillus anthracis and identified PagA, seven members of a N-acetylmuramoyl-L-alanine amidase autolysin family, three P60 family lipoproteins, two transporters, spore cortex lytic protein SleB, a penicillin binding protein, a putative prophage holin, respiratory nitrate reductase NarG, and three proteins of unknown function. Using quantitative real-time PCR comparing RNA isolated from in vitro cultured B. anthracis to RNA isolated from BALB/c mice infected with virulent Ames strain B. anthracis, we confirmed induced expression in vivo for a subset of B. anthracis genes identified by IVIAT, including L-alanine amidases BA3767, BA4073, and amiA (pXO2-42); the bacteriophage holin gene BA4074; and pagA (pXO1-110). The exogenous addition of two purified putative autolysins identified by IVIAT, N-acetylmuramoyl-L-alanine amidases BA0485 and BA2446, to vegetative B. anthracis cell suspensions induced a species-specific change in bacterial morphology and reduction in viable bacterial cells. Many of the proteins identified in our screen are predicted to affect peptidoglycan re-modeling, and our results support significant cell wall structural remodeling activity during B. anthracis infection. Identification of L-alanine amidases with B. anthracis specificity may suggest new potential therapeutic targets. PMID:18350160

  20. Application of in vivo induced antigen technology (IVIAT) to Bacillus anthracis.

    PubMed

    Rollins, Sean M; Peppercorn, Amanda; Young, John S; Drysdale, Melissa; Baresch, Andrea; Bikowski, Margaret V; Ashford, David A; Quinn, Conrad P; Handfield, Martin; Hillman, Jeffrey D; Lyons, C Rick; Koehler, Theresa M; Calderwood, Stephen B; Ryan, Edward T

    2008-03-19

    In vivo induced antigen technology (IVIAT) is an immuno-screening technique that identifies bacterial antigens expressed during infection and not during standard in vitro culturing conditions. We applied IVIAT to Bacillus anthracis and identified PagA, seven members of a N-acetylmuramoyl-L-alanine amidase autolysin family, three P60 family lipoproteins, two transporters, spore cortex lytic protein SleB, a penicillin binding protein, a putative prophage holin, respiratory nitrate reductase NarG, and three proteins of unknown function. Using quantitative real-time PCR comparing RNA isolated from in vitro cultured B. anthracis to RNA isolated from BALB/c mice infected with virulent Ames strain B. anthracis, we confirmed induced expression in vivo for a subset of B. anthracis genes identified by IVIAT, including L-alanine amidases BA3767, BA4073, and amiA (pXO2-42); the bacteriophage holin gene BA4074; and pagA (pXO1-110). The exogenous addition of two purified putative autolysins identified by IVIAT, N-acetylmuramoyl-L-alanine amidases BA0485 and BA2446, to vegetative B. anthracis cell suspensions induced a species-specific change in bacterial morphology and reduction in viable bacterial cells. Many of the proteins identified in our screen are predicted to affect peptidoglycan re-modeling, and our results support significant cell wall structural remodeling activity during B. anthracis infection. Identification of L-alanine amidases with B. anthracis specificity may suggest new potential therapeutic targets.

  1. Redox self-sufficient whole cell biotransformation for amination of alcohols.

    PubMed

    Klatte, Stephanie; Wendisch, Volker F

    2014-10-15

    Whole cell biotransformation is an upcoming tool to replace common chemical routes for functionalization and modification of desired molecules. In the approach presented here the production of various non-natural (di)amines was realized using the designed whole cell biocatalyst Escherichia coli W3110/pTrc99A-ald-adh-ta with plasmid-borne overexpression of genes for an l-alanine dehydrogenase, an alcohol dehydrogenase and a transaminase. Cascading alcohol oxidation with l-alanine dependent transamination and l-alanine dehydrogenase allowed for redox self-sufficient conversion of alcohols to the corresponding amines. The supplementation of the corresponding (di)alcohol precursors as well as amino group donor l-alanine and ammonium chloride were sufficient for amination and redox cofactor recycling in a resting buffer system. The addition of the transaminase cofactor pyridoxal-phosphate and the alcohol dehydrogenase cofactor NAD(+) was not necessary to obtain complete conversion. Secondary and cyclic alcohols, for example, 2-hexanol and cyclohexanol were not aminated. However, efficient redox self-sufficient amination of aliphatic and aromatic (di)alcohols in vivo was achieved with 1-hexanol, 1,10-decanediol and benzylalcohol being aminated best. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. User-Friendly, Syntax Directed Input to a Computer Aided Design System.

    DTIC Science & Technology

    1983-06-01

    indepen- dern-. oblems arise in both compu:er aided design and in software development as a result of multipla types cf computz , mUtiple languages...Base CONLAN. Ease CONLAN is defined cy three i- ms , a set of object types and cperations, syntax, and a comPuta-IoL model. It is defined with Primitive...ycsjum on Computer Hardware= DescrT:--c-: -Lanquaqes. ~ p. =-3’EEET73 28. H1Il, F. J., and Petezzcn, J. R., DjZt4- S Lt-= Ms : Hardware O~gan iza,,i.n cand

  3. A Multiple Bridge for Elimination of Contact-Resistance Errors in Resistance Strain-Gage Measurements

    DTIC Science & Technology

    1946-03-01

    g@ge. ‘ ,, 3. If’&’ ms a,b or h)k are used and a m&ing-coil galva- nometersis the’detector, an appreciable &Gsistance is introductid ‘into this...denoglnator because]it would oontrihuto only third-order % ms .” I;merting equation (39) into the identity- . . iGl ( )‘iG2””b ‘Gl”- ‘G2 (40) (37) may...measurement of alternating strains through slip .rings. --- Ii .,+- ● A A s r r Rh s Two-pole multipla -” position switch R Single-pole multiple

  4. An Analysis of the Effectiveness of the Problem Solving Skills for Managers Training Package--USCG

    DTIC Science & Technology

    1984-03-01

    OH--. I tO I M I I S I I i I w -31 1 C5 1 *- 1 * 1 . l 1 . . -n.. II I I (f) * a , p U U) 1 0014 I In 1 M 1 I -I IC4 I faI (i0d I " mS It mII I I I I...visor "Passing -0.29 92 .769t h_ Buck" 0.0030 H{(A3) Multipla -choic 0.13,49Qua st loan air’s 2.73 35 .010, score 0.0030 H (A4) Subo;dina.. P

  5. ARPA/NRL X-Ray Laser Program - Semiannual Technical Report to Defense Advanced Research Projects Agency

    DTIC Science & Technology

    1975-03-01

    creased line shifts. The (sparse) data16 available on line shifts with multipla M vacancies indicate that an emission-absorption line overlap fortunately...photon (23) 102 ^ümk^^HäiiM,,- ..■^.Ma^fc.^a»aa.t^«fcMif ^a.^ r^^aM^&^-^^a^^^ amik^c^a ummäiiütä&ä^ ms *^ ’UIUVWWIIWW^I.^IM.IPP^WWIUVMJ i4.li...Cavity from a plasma gun or a duoplasmatron injectBa iui.u operation at Lyman-cv at a reduced gcln coefficient Ms been suggested [120], [167], and

  6. Efficiency Analysis of the Electronic Mail System (INFOMAIL) on the Defense Data Network.

    DTIC Science & Technology

    1984-12-01

    the provider of the standard interface. Also the procurement of multipla pieces of equipment .-ith their installation into a user’s facility further...i’Y,: ms provided low cost but effective access to the network rasources. i improve the efficiency of the fkC’s interface with the netwcrk rc -,uirrs...PERSONAL AUTHOR(S) Kevin R. Kavanaugh, BS, Capt, USAF r13. TYPE OF REPORT 13b. TIME COVERED FRO4 DATE OF REPORT Yr, h. Day, f 5 PAGE COUNT * MS Thesis

  7. Role of H{sub 2}O{sub 2} on the kinetics of low-affinity high-capacity Na{sup +}-dependent alanine transport in SHR proximal tubular epithelial cells

    SciTech Connect

    Pinto, Vanda; Pinho, Maria Joao; Jose, Pedro A.; Soares-da-Silva, Patricio

    2010-07-30

    Research highlights: {yields} H{sub 2}O{sub 2} in excess is required for the presence of a low-affinity high-capacity component for the Na{sup +}-dependent [{sup 14}C]-L-alanine uptake in SHR PTE cells only. {yields} It is suggested that Na{sup +} binding in renal ASCT2 may be regulated by ROS in SHR PTE cells. -- Abstract: The presence of high and low sodium affinity states for the Na{sup +}-dependent [{sup 14}C]-L-alanine uptake in immortalized renal proximal tubular epithelial (PTE) cells was previously reported (Am. J. Physiol. 293 (2007) R538-R547). This study evaluated the role of H{sub 2}O{sub 2} on the Na{sup +}-dependent [{sup 14}C]-L-alanine uptake of ASCT2 in immortalized renal PTE cells from Wistar Kyoto rat (WKY) and spontaneously hypertensive rat (SHR). Na{sup +} dependence of [{sup 14}C]-L-alanine uptake was investigated replacing NaCl with an equimolar concentration of choline chloride in vehicle- and apocynin-treated cells. Na{sup +} removal from the uptake solution abolished transport activity in both WKY and SHR PTE cells. Decreases in H{sub 2}O{sub 2} levels in the extracellular medium significantly reduced Na{sup +}-K{sub m} and V{sub max} values of the low-affinity high-capacity component in SHR PTE cells, with no effect on the high-affinity low-capacity state of the Na{sup +}-dependent [{sup 14}C]-L-alanine uptake. After removal of apocynin from the culture medium, H{sub 2}O{sub 2} levels returned to basal values within 1 to 3 h in both WKY and SHR PTE cells and these were found stable for the next 24 h. Under these experimental conditions, the Na{sup +}-K{sub m} and V{sub max} of the high-affinity low-capacity state were unaffected and the low-affinity high-capacity component remained significantly decreased 1 day but not 4 days after apocynin removal. In conclusion, H{sub 2}O{sub 2} in excess is required for the presence of a low-affinity high-capacity component for the Na{sup +}-dependent [{sup 14}C]-L-alanine uptake in SHR PTE cells only

  8. Modelling the effect of a heat shock and germinant concentration on spore germination of a wild strain of Bacillus cereus.

    PubMed

    Collado, J; Fernández, A; Rodrigo, M; Martínez, A

    2006-01-15

    The effect of different concentrations of L-alanine on the germination kinetics of a strain of Bacillus cereus isolated from liquid egg after heat shock during sporulation was studied. Germination at 30 degrees C and was followed by spectrophotometry. The higher the concentration of L-alanine within the range 100-1 mM the faster was the germination obtained. On the other hand, the application of a heat shock had an effect on the germination producing a diminution on the germination kinetic rates. The Weibull distribution function, a model that has been used for describing inactivation kinetics , was used for modelling germination experimental data. Results indicated that the Weibull distribution function model produced a good description of experimental data.

  9. Halogenated DOPA in a Marine Adhesive Protein

    PubMed Central

    Sun, Cheng Jun; Srivastava, Aasheesh; Reifert, Jack R.; Waite, J. Herbert

    2009-01-01

    The sandcastle worm Phragmatopoma californica, a marine polychaete, constructs a tube-like shelter by cementing together sand grains using a glue secreted from the building organ in its thorax. The glue is a mixture of post-translationally modified proteins, notably the cement proteins Pc-1 and Pc-2 with the amino acid, 3,4-dihydroxyphenyl-L-alanine (DOPA). Significant amounts of a halogenated derivative of DOPA were isolated from the worm cement following partial acid hydrolysis and capture of catecholic amino acids by phenylboronate affinity chromatography. Analysis by tandem mass spectrometry and 1H NMR indicates the DOPA derivative to be 2-chloro-4, 5-dihydroxyphenyl-L-alanine. The potential roles of 2-chloro-DOPA in chemical defense and underwater adhesion are considered. PMID:20126508

  10. Addition of amino acids and dipeptides to fullerene C{sub 60} giving rise to monoadducts

    SciTech Connect

    Romanova, V.S.; Tsyryapkin, V.A.; Vol`pin, M.E.

    1994-12-01

    The authors have developed a general method for the direct addition of amino acids and dipeptides of various structures to fullerene C{sub 60}. In all cases the addition involves the amino group. The reaction proceeds when the solutions of fullerene and an amino acid (or dipeptide) are mixed at 50-100 {degrees}C. The fullerene derivatives of the following amino acids and dipeptides have been obtained: glycine, p-aminobenzoic acid, {omega}-aminocaproic acid, L-proline, L-alanine, L-alanyl-Lalanine, D,L-alanyl-D,L-alanine, glycyl-L-valine. The adduct of methyl L-ananinate with C{sub 60} was also prepared.

  11. Aromatic radiofluorination with (/sup 18/F)fluorine gas: 6-(/sup 18/F)fluoro-L-dopa

    SciTech Connect

    Firnau, G.; Chirakal, R.; Garnett, E.S.

    1984-11-01

    A new synthesis is described for the routine production of 3,4-dihydroxy-6-(/sup 18/F)fluoro-phenyl-L-alanine (6-(/sup 18/F)fluoro-L-dopa). The reaction between (/sup 18/F)fluorine gas and 3,4-dihydroxyphenyl-L-alanine (L-dopa) in liquid hydrogen fluoride gave 2-, 5-, and 6-(/sup 18/F)fluoro-L-dopa. 6-(/sup 18/F)Fluoro-L-dopa was isolated by reverse-phase high-pressure liquid chromatography. From 100 mCi (/sup 18/F)F/sub 2/, the method produces 3 mCi of 6-(/sup 18/F)fluoro-L-dopa at the end of synthesis.

  12. Nitrile-synthesizing enzyme: Gene cloning, overexpression and application for the production of useful compounds.

    PubMed

    Kumano, Takuto; Takizawa, Yuko; Shimizu, Sakayu; Kobayashi, Michihiko

    2016-09-12

    One of the nitrile-synthesizing enzymes, β-cyano-L-alanine synthase, catalyzes β-cyano-L-alanine (β-CNAla) from potassium cyanide and O-acetyl-L-serine or L-cysteine. We have identified this enzyme from Pseudomonas ovalis No. 111. In this study, we cloned the β-CNAla synthase gene and expressed it in Escherichia coli and Rhodococcus rhodochrous. Furthermore, we carried out co-expression of β-CNAla synthase with nitrilase or nitrile hydratases in order to synthesize aspartic acid and asparagine from KCN and O-acetyl-L-serine. This strategy can be used for the synthesis of labeled amino acids by using a carbon-labeled KCN as a substrate, resulting in an application for positron emission tomography.

  13. R76 in transmembrane domain 3 of the aspartate:alanine transporter AspT is involved in substrate transport.

    PubMed

    Suzuki, Satomi; Nanatani, Kei; Abe, Keietsu

    2016-01-01

    The L-aspartate:L-alanine antiporter of Tetragenococcus halophilus (AspT) possesses an arginine residue (R76) within the GxxxG motif in the central part of transmembrane domain 3 (TM3)-a residue that has been estimated to transport function. In this study, we carried out amino acid substitutions of R76 and used proteoliposome reconstitution for analyzing the transport function of each substitution. Both l-aspartate and l-alanine transport assays showed that R76K has higher activity than the AspT-WT (R76), whereas R76D and R76E have lower activity than the AspT-WT. These results suggest that R76 is involved in AspT substrate transport.

  14. The 8-amino-7-oxopelargonate synthase from Bacillus sphaericus. Purification and preliminary characterization of the cloned enzyme overproduced in Escherichia coli.

    PubMed Central

    Ploux, O; Marquet, A

    1992-01-01

    The 8-amino-7-oxopelargonate synthase [6-carboxyhexanoyl-CoA:L-alanine carboxyhexanoyltransferase (decarboxylating); EC 2.3.1.47] from Bacillus sphaericus involved in biotin biosynthesis was purified from an Escherichia coli overproducing strain. The purification afforded an electrophoretically homogeneous enzyme with a specific activity of 0.67 unit/mg. The purified enzyme is a monomer of 41 kDa. N-Terminal sequencing of the first 14 amino acid residues showed complete agreement with the predicted sequence from the bioF gene. The pure enzyme showed the characteristic absorption band (425 nm) of pyridoxal 5'-phosphate-dependent enzymes. Furthermore, the holoenzyme was resolved during an affinity step yielding the inactive apoenzyme, which recovered activity and the 425 nm-absorption band on dialysis against pyridoxal 5'-phosphate. Km values for L-alanine and pimeloyl-CoA were respectively 3 mM and 1 microM. Images Fig. 1. PMID:1575677

  15. Asymmetric adsorption by quartz - A model for the prebiotic origin of optical activity

    NASA Technical Reports Server (NTRS)

    Bonner, W. M.; Kavasmaneck, P. R.; Martin, F. S.; Flores, J. J.

    1975-01-01

    One mechanism previously proposed for the abiotic accumulation of molecules of one chirality in nature is asymmetric adsorption on the chiral surfaces of optically active quartz crystals. Earlier literature in this field is reviewed, with the conclusion that previous investigations of this phenomenon, using optical rotation criteria, have afforded ambiguous results. We now have studied the adsorption of radioactive D- and L-alanine on powdered d- and l-quartz, using change in radioactivity level as a criterion for both gross and differential adsorption, d-Quartz preferentially adsorbed D-alanine from anhydrous dimethyl-formamide solution, and l-quartz L-alanine. The differential adsorption varied between 1.0 and 1.8%. The implications of these observations are discussed from the viewpoint of early chemical evolution and the origin of optically active organic compounds in nature.

  16. First-principles studies of pure and fluorine substituted alanines

    NASA Astrophysics Data System (ADS)

    Ahmad, Sardar; Vaizie, Hamide; Rahnamaye Aliabad, H. A.; Ahmad, Rashid; Khan, Imad; Ali, Zahid; Jalali-Asadabadi, S.; Ahmad, Iftikhar; Khan, Amir Abdullah

    2016-05-01

    This paper communicates the structural, electronic and optical properties of L-alanine, monofluoro and difluoro substituted alanines using density functional calculations. These compounds exist in orthorhombic crystal structure and the calculated structural parameters such as lattice constants, bond angles and bond lengths are in agreement with the experimental results. L-alanine is an indirect band gap insulator, while its fluorine substituted compounds (monofluoroalanine and difluoroalanine) are direct band gap insulators. The substitution causes reduction in the band gap and hence these optically tailored direct wide band gap materials have enhanced optical properties in the ultraviolet (UV) region of electromagnetic spectrum. Therefore, optical properties like dielectric function, refractive index, reflectivity and energy loss function are also investigated. These compounds have almost isotropic nature in the lower frequency range while at higher energies, they have a significant anisotropic nature.

  17. Asymmetric adsorption by quartz - A model for the prebiotic origin of optical activity

    NASA Technical Reports Server (NTRS)

    Bonner, W. M.; Kavasmaneck, P. R.; Martin, F. S.; Flores, J. J.

    1975-01-01

    One mechanism previously proposed for the abiotic accumulation of molecules of one chirality in nature is asymmetric adsorption on the chiral surfaces of optically active quartz crystals. Earlier literature in this field is reviewed, with the conclusion that previous investigations of this phenomenon, using optical rotation criteria, have afforded ambiguous results. We now have studied the adsorption of radioactive D- and L-alanine on powdered d- and l-quartz, using change in radioactivity level as a criterion for both gross and differential adsorption, d-Quartz preferentially adsorbed D-alanine from anhydrous dimethyl-formamide solution, and l-quartz L-alanine. The differential adsorption varied between 1.0 and 1.8%. The implications of these observations are discussed from the viewpoint of early chemical evolution and the origin of optically active organic compounds in nature.

  18. [Raman scattering study of DL-alanine].

    PubMed

    Gong, Yan; Wang, Wen-qing

    2006-01-01

    Studies of Raman vibration spectra are useful to obtaining information on biomolecular crystals. The cell dimensions of the L- and DL-alanine crystals are nearly identical, and both structures belong to the orthorhombic system, but the space group is P2(1) 2(1) 2(1) for the L-isomer, and Pna2(1) for the racemate crystal. The Raman spectrum of L-alanine has been measured by many authors. The present work is focusing on the Raman scattering study of DL-alanine powder. Based on the analysis of the differences between DL-alanine and L-alanine Raman spectra, the authors obtained indispensable information on hydrogen bond and the motion of the molecular conformation in alanine crystals.

  19. Probing crystal packing of uniformly (13)C-enriched powder samples using homonuclear dipolar coupling measurements.

    PubMed

    Mollica, Giulia; Dekhil, Myriam; Ziarelli, Fabio; Thureau, Pierre; Viel, Stéphane

    2015-02-01

    The relationship between the crystal packing of powder samples and long-range (13)C-(13)C homonuclear dipolar couplings is presented and illustrated for the case of uniformly (13)C-enriched L-alanine and L-histidine·HCl·H2O. Dipolar coupling measurement is based on the partial reintroduction of dipolar interactions by spinning the sample slightly off-magic-angle, while the coupling of interest for a given spin pair is isolated with a frequency-selective pulse. A cost function is used to correlate the so-derived dipolar couplings to trial crystal structures of the samples under study. This procedure allowed for the investigation of the l-alanine space group and L-histidine·HCl·H2O space group and unit-cell parameters.

  20. Inter and intra plant variability of enzyme profiles including various phosphoesterases and sulfatase of six wastewater treatment plants.

    PubMed

    Fischer, Klaus; Wolff, Bert; Emmerling, Christoph

    2013-06-01

    Biodegradation of organic wastewater constituents by activated sludge microorganisms is based on enzymatic processes. It is supposed that wastewater treatment plants (WWTP) differ in their enzymatic fingerprints. To determine such fingerprints, activated sludges from nine aerated tanks of six WWTPs were repeatedly sampled and analyzed for the activities of l-alanine aminopeptidase, esterase, α- and β-glucosidase, alkaline phosphatase, phosphodiesterase, phosphotriesterase, and sulfatase. In one WWTP the enzymatic activities and their variations within 1 week were assayed in various process stages. Mostly the enzymatic profiles were dominated by l-alanine aminopeptidase, followed by alkaline phosphatase. They differed in variable contributions of esterase, phosphodiesterase, α- and β-glucosidase. The sulfatase activity was generally low. For the first time phosphotriesterase activity was detected in various samples, but with limited analytical validity. Particle mass-related activities of individual enzymes varied between plants by factors 2-4 and up to 11, when related to suspension volumes.

  1. Substrate specificity and some physicochemical properties of autolytic enzymes of the bacterium Lysobacter sp. XL 1.

    PubMed

    Tsfasman, I M; Sitkin, B V; Lysanskaya, V Ya; Stepnaya, O A; Kulaev, I S

    2007-07-01

    The substrate specificity of autolytic enzymes of the bacterium Lysobacter sp. XL 1 has been established. The periplasmic enzyme A8, the cytosolic enzyme A1, and the enzyme A10 solubilized from the cell walls and membranes with Triton X-100 exhibit glucosaminidase activity; the cytosolic enzyme A4 and the enzyme A9 solubilized from the cell walls and membranes with LiCl exhibit the muramidase activity. The cytosolic enzymes A3 and A6 have N-acetylmuramoyl-L-alanine amidase activity, and the enzyme A5 exhibits the diaminopimelinoyl-alanine endopeptidase activity. Some physicochemical properties of the most active autolytic cytosolic enzymes of Lysobacter sp. XL 1 (endopeptidases A5 and A7 and N-acetylmuramoyl-L-alanine amidase A6) were studied. The enzymes exhibit maximal activity over a wide range of buffer concentrations in weakly alkaline medium and moderate temperatures. The investigated enzymes are comparatively thermolabile proteins.

  2. A silaproline-containing dipeptide.

    PubMed

    Vivet, B; Cavelier, F; Martinez, J; Didierjean, C; Marraud, M; Aubry, A

    2000-12-01

    The silaproline-containing dipeptide N-(3, 3-dimethyl-1-pivaloyl-1-aza-3-sila-5-cyclopentylcarbonyl)-L- alanine isopropylamide, C(17)H(33)N(3)O(3)Si, has two independent molecules in the asymmetric unit and each adopts a beta-II folded conformation, where the amide on the terminal C interacts intramolecularly with the pivaloyl O atom. The five-membered silaproline ring is C(beta)-puckered, an infrequent conformation for the homologous proline ring.

  3. Monitoring of shrimp and farmed fish sold in Canada for cyanobacterial toxins.

    PubMed

    Niedzwiadek, Barbara; Scott, Peter M; Lau, Ben P-Y

    2012-01-01

    Sixty-one samples of shrimp and 32 samples of farmed fish collected from retail markets across Canada were analyzed for cyanobacterial toxins, including microcystins, paralytic shellfish poisons (saxitoxins), cylindrospermopsin, and β-N-methylamino-L-alanine, using established methods of analysis. None of these toxins were detected in any of the samples. Some shrimp samples screened for paralytic shellfish poisons showed the presence of unknown peaks in the chromatogram after periodate oxidation.

  4. Presynaptic Modulation of the Hippocampal Mossy Fiber Synapse

    DTIC Science & Technology

    1990-09-14

    effects of the neurotoxic amino acids BOAA and beta-N-methylamino-L-alanine ( BMAA ) on the release of both glutamate and dynorphin A(1-8) from...hippocampal mossy fiber synaptosomes. Our interest in these amino acids arose from the recent suggestion that BOAA and BMAA exert their neurotoxic effects on...the central nervous system by increasing the release of glutamate. We found that the non-NMDA receptor agonist BOAA but not BMAA , an NMDA agonist

  5. The Aspergillus nidulans Proline Permease as a Model for Understanding the Factors Determining Substrate Binding and Specificity of Fungal Amino Acid Transporters*

    PubMed Central

    Gournas, Christos; Evangelidis, Thomas; Athanasopoulos, Alexandros; Mikros, Emmanuel; Sophianopoulou, Vicky

    2015-01-01

    Amino acid uptake in fungi is mediated by general and specialized members of the yeast amino acid transporter (YAT) family, a branch of the amino acid polyamine organocation (APC) transporter superfamily. PrnB, a highly specific l-proline transporter, only weakly recognizes other Put4p substrates, its Saccharomyces cerevisiae orthologue. Taking advantage of the high sequence similarity between the two transporters, we combined molecular modeling, induced fit docking, genetic, and biochemical approaches to investigate the molecular basis of this difference and identify residues governing substrate binding and specificity. We demonstrate that l-proline is recognized by PrnB via interactions with residues within TMS1 (Gly56, Thr57), TMS3 (Glu138), and TMS6 (Phe248), which are evolutionary conserved in YATs, whereas specificity is achieved by subtle amino acid substitutions in variable residues. Put4p-mimicking substitutions in TMS3 (S130C), TMS6 (F252L, S253G), TMS8 (W351F), and TMS10 (T414S) broadened the specificity of PrnB, enabling it to recognize more efficiently l-alanine, l-azetidine-2-carboxylic acid, and glycine without significantly affecting the apparent Km for l-proline. S253G and W351F could transport l-alanine, whereas T414S, despite displaying reduced proline uptake, could transport l-alanine and glycine, a phenotype suppressed by the S130C mutation. A combination of all five Put4p-ressembling substitutions resulted in a functional allele that could also transport l-alanine and glycine, displaying a specificity profile impressively similar to that of Put4p. Our results support a model where residues in these positions determine specificity by interacting with the substrates, acting as gating elements, altering the flexibility of the substrate binding core, or affecting conformational changes of the transport cycle. PMID:25572393

  6. Biomagnification of cycad neurotoxins in flying foxes: implications for ALS-PDC in Guam.

    PubMed

    Banack, Sandra Anne; Cox, Paul Alan

    2003-08-12

    Beta-methylamino-L-alanine (BMAA) occurs in higher levels in museum specimens of the Guamanian flying fox than in the cycad seeds the flying foxes feed on, confirming the hypothesis that cycad neurotoxins are biomagnified within the Guam ecosystem. Consumption of a single flying fox may have resulted in an equivalent BMAA dose obtained from eating 174 to 1,014 kg of processed cycad flour. Traditional feasting on flying foxes may be related to the prevalence of neuropathologic disease in Guam.

  7. Neurogenin1 Expression and Function in the Developing Mouse Cerebellum

    DTIC Science & Technology

    2011-12-14

    natural Cre recombinase from Bacteriophage P1 at the predicted 38.5 kDa size by SDS-PAGE Western blot (manufacturer’s technical information). (7) 1...L-glutamine, taurine , putrescine, L-alanine, and carnosine. The antibody has weak cross reactivity to β-alanine and ε-aminocaproic acid (all...cell lineages. Many studies of bHLH factors have highlighted the combinatorial nature of these proteins in their specification of neuronal subtypes

  8. Enzymic synthesis of γ-coniceine in Conium maculatum chloroplasts and mitochondria.

    PubMed

    Roberts, M F

    1981-08-01

    Further studies of the transaminase responsible for the first committed step in alkaloid formation in Conium maculatum have shown the L-alanine: 5-ketooctanal transaminase to occur in both the mitochondria and chloroplast. Experiments suggest that these enzymes are the isoenzymes Transaminase A and B respectively previously isolated by the author. It is suggested that the chloroplast enzyme is normally responsible for alkaloid production.

  9. Purification and characterization of selenocysteine beta-lyase from Citrobacter freundii.

    PubMed Central

    Chocat, P; Esaki, N; Tanizawa, K; Nakamura, K; Tanaka, H; Soda, K

    1985-01-01

    The purification and characterization of bacterial selenocysteine beta-lyase, an enzyme which specifically catalyzes the cleavage of L-selenocysteine to L-alanine and Se0, are presented. The enzyme, purified to near homogeneity from Citrobacter freundii, is monomeric with a molecular weight of ca. 64,000 and contains 1 mol of pyridoxal 5'-phosphate as a cofactor per mol of enzyme. L-Selenocysteine is the sole substrate (Km, 0.95 mM). L-Cysteine is a competitive inhibitor of the enzyme (Ki, 0.65 mM). The enzyme also catalyzes the alpha, beta elimination of beta-chloro-L-alanine to form NH3, pyruvate, and Cl- and is irreversibly inactivated during the reaction. The physicochemical properties, e.g., amino acid composition and subunit structure, of the bacterial enzyme are fairly different from those of the pig liver enzyme (Esaki et al., J. Biol. Chem. 257:4386-4391, 1982). However, the catalytic properties of both enzymes, e.g., substrate specificity and inactivation by the substrate or a mechanism-based inactivator, beta-chloro-L-alanine, are very similar. PMID:2991201

  10. Characterization of alanine catabolism in Pseudomonas aeruginosa and its importance for proliferation in vivo.

    PubMed

    Boulette, Megan L; Baynham, Patricia J; Jorth, Peter A; Kukavica-Ibrulj, Irena; Longoria, Aissa; Barrera, Karla; Levesque, Roger C; Whiteley, Marvin

    2009-10-01

    The opportunistic pathogen Pseudomonas aeruginosa causes a variety of infections in immunocompromised individuals, including individuals with the heritable disease cystic fibrosis. Like the carbon sources metabolized by many disease-causing bacteria, the carbon sources metabolized by P. aeruginosa at the host infection site are unknown. We recently reported that l-alanine is a preferred carbon source for P. aeruginosa and that two genes potentially involved in alanine catabolism (dadA and dadX) are induced during in vivo growth in the rat peritoneum and during in vitro growth in sputum (mucus) collected from the lungs of individuals with cystic fibrosis. The goals of this study were to characterize factors required for alanine catabolism in P. aeruginosa and to assess the importance of these factors for in vivo growth. Our results reveal that dadA and dadX are arranged in an operon and are required for catabolism of l-alanine. The dad operon is inducible by l-alanine, d-alanine, and l-valine, and induction is dependent on the transcriptional regulator Lrp. Finally, we show that a mutant unable to catabolize dl-alanine displays decreased competitiveness in a rat lung model of infection.

  11. Biological activities of indoleacetylamino acids and their use as auxins in tissue culture.

    PubMed

    Hangarter, R P; Peterson, M D; Good, N E

    1980-05-01

    THE AUXIN ACTIVITIES OF A NUMBER OF INDOLEACETYLAMINO ACID CONJUGATES HAVE BEEN DETERMINED IN THREE TEST SYSTEMS: growth of tomato hypocotyl explants (Lycopersicon esculentum Mill. cv. Marglobe); growth of tobacco callus cultures (Nicotiana tabacum L. cv. Wisconsin 38); and ethylene production from pea stems (Pisum sativum L. cv. Alaska). The activities of the conjugates differ greatly depending on the amino acid moiety. Indoleacetyl-l-alanine supports rapid callus growth from the tomato hypocotyls while inhibiting growth of shoots and roots. Indoleacetylglycine behaves in a similar manner but is somewhat less effective in supporting callus growth and in inhibiting shoot formation. The other amino acid conjugates tested (valine, leucine, aspartic acid, threonine, methionine, phenylalanine, and proline) support shoot formation without supporting root formation or much callus growth. The tobacco callus system, which forms abundant shoots in the presence or absence of free indoleacetic acid, produces only rapid undifferentiated growth in the presence of indoleacetyl-l-alanine and indoleacetylglycine. The other conjugates inhibit shoot formation weakly if at all. Most of the conjugates induce sustained ethylene production from the pea stems but at rates well below the initial rates observed with free indoleacetic acid. Many, but not all of the effects of conjugates such as indoleacetyl-l-alanine can be mimicked by frequent renewals of the supply of free indoleacetic acid.

  12. Biological Activities of Indoleacetylamino Acids and Their Use as Auxins in Tissue Culture 1

    PubMed Central

    Hangarter, Roger P.; Peterson, Michael D.; Good, Norman E.

    1980-01-01

    The auxin activities of a number of indoleacetylamino acid conjugates have been determined in three test systems: growth of tomato hypocotyl explants (Lycopersicon esculentum Mill. cv. Marglobe); growth of tobacco callus cultures (Nicotiana tabacum L. cv. Wisconsin 38); and ethylene production from pea stems (Pisum sativum L. cv. Alaska). The activities of the conjugates differ greatly depending on the amino acid moiety. Indoleacetyl-l-alanine supports rapid callus growth from the tomato hypocotyls while inhibiting growth of shoots and roots. Indoleacetylglycine behaves in a similar manner but is somewhat less effective in supporting callus growth and in inhibiting shoot formation. The other amino acid conjugates tested (valine, leucine, aspartic acid, threonine, methionine, phenylalanine, and proline) support shoot formation without supporting root formation or much callus growth. The tobacco callus system, which forms abundant shoots in the presence or absence of free indoleacetic acid, produces only rapid undifferentiated growth in the presence of indoleacetyl-l-alanine and indoleacetylglycine. The other conjugates inhibit shoot formation weakly if at all. Most of the conjugates induce sustained ethylene production from the pea stems but at rates well below the initial rates observed with free indoleacetic acid. Many, but not all of the effects of conjugates such as indoleacetyl-l-alanine can be mimicked by frequent renewals of the supply of free indoleacetic acid. Images PMID:16661279

  13. Development of fast disintegrating compressed tablets using amino acid as disintegration accelerator: evaluation of wetting and disintegration of tablet on the basis of surface free energy.

    PubMed

    Fukami, Jinichi; Ozawa, Asuka; Yoshihashi, Yasuo; Yonemochi, Etsuo; Terada, Katsuhide

    2005-12-01

    A fast disintegrating compressed tablet was formulated using amino acids, such as L-lysine HCl, L-alanine, glycine and L-tyrosine as disintegration accelerator. The tablets having the hardness of about 4 kgf were prepared and the effect of amino acids on the wetting time and disintegration time in the oral cavity of tablets was examined on the basis of surface free energy of amino acids. The wetting time of the tablets increased in the order of L-lysine HCl, L-alanine, glycine and L-tyrosine, whereas the disintegration time in the oral cavity of the tablets increased in the order of L-alanine, glycine, L-lysine HCl and L-tyrosine. These behaviors were well analyzed by the introduction of surface free energy. When the polar component of amino acid was large value or the dispersion component was small value, faster wetting of tablet was observed. When the dispersion component of amino acid was large value or the dispersion component was small value, faster disintegration of tablet was observed, expect of L-tyrosine tablet. The fast disintegration of tablets was explained by the theory presented by Matsumaru.

  14. Investigation of gamma radiation effect on chemical properties and surface morphology of some nonlinear optical (NLO) single crystals

    NASA Astrophysics Data System (ADS)

    Ahlam, M. A.; Ravishankar, M. N.; Vijayan, N.; Govindaraj, G.; Siddaramaiah; Gnana Prakash, A. P.

    2012-05-01

    The effect of Co-60 gamma irradiation on L-alanine cadmium chloride (LACC), L-alanine doped potassium dihydrogen orthophosphate (KDP) and L-arginine doped KDP nonlinear optical (NLO) single crystals were studied in doses ranging from 100 krad to 6 Mrad. The crystals were grown by slow evaporation method at room temperature. The effects of gamma irradiation on the chemical, surface morphology, DC electrical conductivity, thermal and mechanical properties of the grown crystals have been studied. The functional groups of unirradiated and irradiated crystals have been identified and confirmed by Fourier transform infrared (FTIR) studies. Scanning electron microscopy (SEM) of irradiated crystals shows some morphological changes in the crystals. The dc conductivity of LACC and L-alanine doped KDP crystals were found to increase with increase in radiation dose whereas in case of L-arginine doped KDP crystals, the dc conductivity was found to decrease with increase in radiation dose. Differential scanning calorimetry (DSC) thermograms reveals that there is no significant change in the melting point of the crystals after irradiation and the crystals does not decompose as a result of irradiation. The mechanical behavior of both unirradiated and irradiated crystals is explained with the indentation effects using Vicker's microhardness tester. The Vicker's hardness number HV and Mayer's index 'n' has been estimated and confirms that LACC belong to the hard materials.

  15. The impact of synthetic analogs of histidine on copper(II) and nickel(II) coordination properties to an albumin-like peptide. Possible leads towards new metallodrugs.

    PubMed

    Zawisza, Izabela; Mital, Mariusz; Polkowska-Nowakowska, Agnieszka; Bonna, Arkadiusz; Bal, Wojciech

    2014-10-01

    The purpose of our research was to obtain peptidomimetics possessing Cu(II) and Ni(II) binding properties, which would be useful for biomedical applications. In this context we used potentiometry, UV-VIS and CD spectroscopies to characterize the Cu(II) and Ni(II) binding properties of pentapeptide analogs of the N-terminal sequence of histatin 5. The peptides investigated had a general sequence DSXAK-am (am stands for C-terminal amide), with X including His and its three synthetic analogs, (4-thiazolyl)-L-alanine (1), (2-pyridyl)-L-alanine (2), and (pyrazol-1-yl)-L-alanine (3). The heterocyclic nitrogens present in these analogs were significantly more acidic than that of the His imidazole. We found that DSXAK-am peptides were able to bind Cu(II) and Ni(II) and form 4N complexes in a cooperative fashion, with similar affinities. These results indicate that acidic heterocyclic amino acids provide a viable alternative for histidine in peptidomimetics designed for metal ion binding.

  16. Effects of high-salinity seawater acclimation on the levels of D-alanine in the muscle and hepatopancreas of kuruma prawn, Marsupenaeus japonicus.

    PubMed

    Yoshikawa, Naoko; Yokoyama, Masahumi

    2015-12-10

    Changes in D- and L-alanine contents were determined in the muscle and hepatopancreas of kuruma prawn Marsupenaeus japonicus, during acclimation from seawater containing 100% salinity to artificial seawater containing 150% salinity. In the hepatopancreas, contents of both amino acids increased by approximately threefold. The activity of alanine racemase, which catalyzes the interconversion of D- and L-alanine, also increased in the high-salinity seawater. In addition, the expression of the gene encoding alanine racemase increased in the hepatopancreas with an increase in the alanine racemase activity. These data indicate that the biosynthesis of D- and L-alanine is controlled by the gene expression level of alanine racemase, and D-alanine in the hepatopancreas functions as a major osmolyte for isosmotic regulation. In contrast, the content of D-alanine and alanine racemase activity did not change in the muscle during hyper-osmotic acclimation. Therefore, we suggest that D-alanine, which exists in the several tissues of M. japonicus, is considered to be utilized in some different physiological phenomena in different tissues.

  17. Partial enzymatic elimination and quantification of sarcosine from alanine using liquid chromatography-tandem mass spectrometry.

    PubMed

    Burton, Casey; Gamagedara, Sanjeewa; Ma, Yinfa

    2013-04-01

    Since sarcosine and D,L-alanine co-elute on reversed-phase high-performance liquid chromatography (HPLC) columns and the tandem mass spectrometer cannot differentiate them due to equivalent parent and fragment ions, derivatization is often required for analysis of sarcosine in LC/MS systems. This study offers an alternative to derivatization by employing partial elimination of sarcosine by enzymatic oxidation. The decrease in apparent concentration from the traditionally merged sarcosine-alanine peak associated with the enzymatic elimination has been shown to be proportional to the total sarcosine present (R(2) = 0.9999), allowing for determinations of urinary sarcosine. Sarcosine oxidase was shown to eliminate only sarcosine in the presence of D,L-alanine, and was consequently used as the selective enzyme. This newly developed technique has a method detection limit of 1 μg/L (parts per billion) with a linear range of 3 ppb-1 mg/L (parts per million) in urine matrices. The method was further validated through spiked recoveries of real urine samples, as well as the analysis of 35 real urine samples. The average recoveries for low, middle, and high sarcosine concentration spikes were 111.7, 90.8, and 90.1 %, respectively. In conclusion, this simple enzymatic approach coupled with HPLC/MS/MS is able to resolve sarcosine from D,L-alanine leading to underivatized quantification of sarcosine.

  18. Response of Bacillus Spores to Combinations of Germinative Compounds

    PubMed Central

    Foerster, Harold F.; Foster, J. W.

    1966-01-01

    Foerster, Harold F. (University of Texas, Austin), and J. W. Foster. Response of Bacillus spores to combinations of germinative compounds. J. Bacteriol. 91:1168–1177. 1966.—Spores of 21 strains of Bacillus megaterium and 25 other strains representing 13 species of Bacillus were produced under standardized conditions. The germination of a washed spore suspension of each strain was measured as a response to various combinations of 30 different germinative compounds. The strains were first typed with respect to their response to “primary” germination compounds, i.e., glucose, l-alanine, inosine, and l-alanine-inosine mixture, and also Na+ and K+. The second stage was the determination of the response to various organic and inorganic anions and cations, each strain being supplied with the “primary” compounds best for it. Marked differences in germination patterns were observed among species and strains of the same species. No relation to established taxonomic lines was evident. A nonspecific requirement for ions was found for all strains, but not all ions were effective. A striking degree of interchangeability of germinative chemicals was found. “Fractional germination” was very common. A mixture of l-alanine and inosine and various ions was the best germinative solution for most strains. Some anomalous germination patterns were encountered. Those studied included a strain whose cells lysed spontaneously upon germination and other strains for which l-leucine had striking germinative powers. PMID:4956331

  19. Biological activities of indoleacetylamino acids and their use as auxins in tissue culture

    SciTech Connect

    Hangarter, R.P.; Peterson, M.D.; Good, N.E.

    1980-05-01

    The auxin activities of a number of indoleacetylamino acid conjugates have been determined in three test systems: growth of tomato hypocotyl explants (Lycopersicon esculentum Mill. cv. Marglobe); growth of tobacco callus cultures (Nicotiana tabacum L. cv. Wisconsin 38); and ethylene production from pea stems (Pisum sativum L. cv. Alaska). The activities of the conjugates differ greatly depending on the amino acid moiety. Indoleacetyl-L-alanine supports rapid callus growth from the tomato hypocotyls while inhibiting growth of shoots and roots. Indoleacetlyglycine behaves in a similar manner but is somewhat less effective in supporting callus growth and in inhibiting growth of shoots and roots. Indoleacetylglycine behaves in a similar manner but is somewhat less effective in supporting callus growth and in inhibiting shoot formation. The other amino acid conjugates tested (valine, leucine, aspartic acid, threonine, methionine, phenylalanine, and proline) support shoot formation without supporting root formation or much callus growth. The tobacco callus system, which forms abundant shoots in the presence or absence of free indoleacetic acid, produces only rapid undifferentiated growth in the presence of indoleacetyl-L-alanine and indoleacetylglycine. The other conjugates inhibit shoot formatin weakly if at all. Most of the conjugates induce sustained ethylene production from the pea stems but at rates well below the initial rates observed with free indoleacetic acid. Many, but not all of the effects of conjugates such as indoleacetyl-L-alanine can be mimicked by frequent renewals of the supply of free indoleacetic acid.

  20. Inhibition of Alanine Aminotransferase in Silico and in Vivo Promotes Mitochondrial Metabolism to Impair Malignant Growth*

    PubMed Central

    Beuster, Gregor; Zarse, Kim; Kaleta, Christoph; Thierbach, René; Kiehntopf, Michael; Steinberg, Pablo; Schuster, Stefan; Ristow, Michael

    2011-01-01

    Cancer cells commonly exhibit increased nonoxidative d-glucose metabolism whereas induction of mitochondrial metabolism may impair malignant growth. We have first used an in silico method called elementary mode analysis to identify inhibition of ALAT (l-alanine aminotransferase) as a putative target to promote mitochondrial metabolism. We then experimentally show that two competitive inhibitors of ALAT, l-cycloserine and β-chloro-l-alanine, inhibit l-alanine production and impair d-glucose uptake of LLC1 Lewis lung carcinoma cells. The latter inhibition is linked to an initial energy deficit, as quantified by decreased ATP content, which is then followed by an activation of AMP-activated protein kinase and subsequently increased respiration rates and mitochondrial production of reactive oxygen species, culminating in ATP replenishment in ALAT-inhibited LLC1 cells. Moreover, we observe altered phosphorylation of p38 MAPK (mitogen-activated protein kinase 14), ERK (extracellular signal-regulated kinase 1/2), and Rb1 (retinoblastoma 1) proteins, as well as decreased expression of Cdc25a (cell decision cycle 25 homolog A) and Cdk4 (cyclin-dependent kinase 4). Importantly, these sequelae of ALAT inhibition culminate in similarly reduced anchorage-dependent and anchorage-independent growth rates of LLC1 cells, together suggesting that inhibition of ALAT efficiently impairs cancer growth by counteracting the Warburg effect due to compensatory activation of mitochondrial metabolism. PMID:21540181

  1. Deficiency in l-Serine Deaminase Interferes with One-Carbon Metabolism and Cell Wall Synthesis in Escherichia coli K-12▿

    PubMed Central

    Zhang, Xiao; El-Hajj, Ziad W.; Newman, Elaine

    2010-01-01

    Escherichia coli K-12 provided with glucose and a mixture of amino acids depletes l-serine more quickly than any other amino acid even in the presence of ammonium sulfate. A mutant without three 4Fe4S l-serine deaminases (SdaA, SdaB, and TdcG) of E. coli K-12 is unable to do this. The high level of l-serine that accumulates when such a mutant is exposed to amino acid mixtures starves the cells for C1 units and interferes with cell wall synthesis. We suggest that at high concentrations, l-serine decreases synthesis of UDP-N-acetylmuramate-l-alanine by the murC-encoded ligase, weakening the cell wall and producing misshapen cells and lysis. The inhibition by high l-serine is overcome in several ways: by a large concentration of l-alanine, by overproducing MurC together with a low concentration of l-alanine, and by overproducing FtsW, thus promoting septal assembly and also by overexpression of the glycine cleavage operon. S-Adenosylmethionine reduces lysis and allows an extensive increase in biomass without improving cell division. This suggests that E. coli has a metabolic trigger for cell division. Without that reaction, if no other inhibition occurs, other metabolic functions can continue and cells can elongate and replicate their DNA, reaching at least 180 times their usual length, but cannot divide. PMID:20729359

  2. Deficiency in L-serine deaminase interferes with one-carbon metabolism and cell wall synthesis in Escherichia coli K-12.

    PubMed

    Zhang, Xiao; El-Hajj, Ziad W; Newman, Elaine

    2010-10-01

    Escherichia coli K-12 provided with glucose and a mixture of amino acids depletes L-serine more quickly than any other amino acid even in the presence of ammonium sulfate. A mutant without three 4Fe4S L-serine deaminases (SdaA, SdaB, and TdcG) of E. coli K-12 is unable to do this. The high level of L-serine that accumulates when such a mutant is exposed to amino acid mixtures starves the cells for C(1) units and interferes with cell wall synthesis. We suggest that at high concentrations, L-serine decreases synthesis of UDP-N-acetylmuramate-L-alanine by the murC-encoded ligase, weakening the cell wall and producing misshapen cells and lysis. The inhibition by high L-serine is overcome in several ways: by a large concentration of L-alanine, by overproducing MurC together with a low concentration of L-alanine, and by overproducing FtsW, thus promoting septal assembly and also by overexpression of the glycine cleavage operon. S-Adenosylmethionine reduces lysis and allows an extensive increase in biomass without improving cell division. This suggests that E. coli has a metabolic trigger for cell division. Without that reaction, if no other inhibition occurs, other metabolic functions can continue and cells can elongate and replicate their DNA, reaching at least 180 times their usual length, but cannot divide.

  3. Purification and gene cloning of alpha-methylserine aldolase from Ralstonia sp. strain AJ110405 and application of the enzyme in the synthesis of alpha-methyl-L-serine.

    PubMed

    Nozaki, Hiroyuki; Kuroda, Shinji; Watanabe, Kunihiko; Yokozeki, Kenzo

    2008-12-01

    By screening microorganisms that are capable of assimilating alpha-methyl-DL-serine, we detected alpha-methylserine aldolase in Ralstonia sp. strain AJ110405, Variovorax paradoxus AJ110406, and Bosea sp. strain AJ110407. A homogeneous form of this enzyme was purified from Ralstonia sp. strain AJ110405, and the gene encoding the enzyme was cloned and expressed in Escherichia coli. The enzyme appeared to be a homodimer consisting of identical subunits, and its molecular mass was found to be 47 kDa. It contained 0.7 to 0.8 mol of pyridoxal 5'-phosphate per mol of subunit and could catalyze the interconversion of alpha-methyl-L-serine to L-alanine and formaldehyde in the absence of tetrahydrofolate. Formaldehyde was generated from alpha-methyl-L-serine but not from alpha-methyl-D-serine, L-serine, or D-serine. Alpha-methyl-L-serine synthesis activity was detected when L-alanine was used as the substrate. In contrast, no activity was detected when D-alanine was used as the substrate. In the alpha-methyl-L-serine synthesis reaction, the enzymatic activity was inhibited by an excess amount of formaldehyde, which was one of the substrates. We used cells of E. coli as a whole-cell catalyst to express the gene encoding alpha-methylserine aldolase and effectively obtained a high yield of optically pure alpha-methyl-L-serine using L-alanine and formaldehyde.

  4. Small Arms Handbook WS - 1

    DTIC Science & Technology

    1966-01-01

    single and multiple moving targets. sound targets And a combination of sound and multipla mc~ving targets. Tests are conducted at tile end of these...therefore, are Lalled "active" syste ms . ’A~.tve ’ nfrarcd systents are ous~.e;stible to dote~~tion by a properly equipped enemy. d. Filtered infrared tight...Sim u e nt n% ,IiI withl the d vic’ how i it’ F iu re 5. ms ytmI*n isdI -rhis ~oxwit M.14 or M. Rifle $-anl be ugcq an all Rifie sqa~i TA"I’w c of F

  5. Microwave Heating of Crystals with Gold Nanoparticles and Synovial Fluid under Synthetic Skin Patches

    PubMed Central

    2017-01-01

    Gout is a disease with elusive treatment options. Reduction of the size of l-alanine crystals as a model crystal for gouty tophi with the use of a monomode solid-state microwave was examined as a possible therapeutic aid. The effect of microwave heating on l-alanine crystals in the presence of gold nanoparticles (Au NPs) in solution and synovial fluid (SF) in a plastic pouch through a synthetic skin patch was investigated. In this regard, three experimental paradigms were employed: Paradigm 1 includes the effect of variable microwave power (5–10 W) and variable heating time (5–60 s) and Au NPs in water (20 nm size, volume of 10 μL) in a plastic pouch (1 × 2 cm2 in size). Paradigm 2 includes the effect of a variable volume of 20 nm Au NPs in a variable volume of SF up to 100 μL in a plastic pouch at a constant microwave power (10 W) for 30 s. Paradigm 3 includes the effect of constant microwave power (10 W) and microwave heating time (30 s), constant volume of Au NPs (100 μL), and variable size of Au NPs (20–200 nm) placed in a plastic pouch through a synthetic skin patch. In these experiments, an average of 60–100% reduction in the size of an l-alanine crystal (initial size = 450 μm) without damage to the synthetic skin or increasing the temperature of the samples beyond the physiological range was reported. PMID:28983527

  6. Microwave Heating of Crystals with Gold Nanoparticles and Synovial Fluid under Synthetic Skin Patches.

    PubMed

    McLemore, Gabrielle L; Toker, Salih; Boone-Kukoyi, Zainab; Ajifa, Hillary; Lansiquot, Carisse; Nwawulu, Chinenye; Onyedum, Stanley; Kioko, Bridgit M; Aslan, Kadir

    2017-09-30

    Gout is a disease with elusive treatment options. Reduction of the size of l-alanine crystals as a model crystal for gouty tophi with the use of a monomode solid-state microwave was examined as a possible therapeutic aid. The effect of microwave heating on l-alanine crystals in the presence of gold nanoparticles (Au NPs) in solution and synovial fluid (SF) in a plastic pouch through a synthetic skin patch was investigated. In this regard, three experimental paradigms were employed: Paradigm 1 includes the effect of variable microwave power (5-10 W) and variable heating time (5-60 s) and Au NPs in water (20 nm size, volume of 10 μL) in a plastic pouch (1 × 2 cm(2) in size). Paradigm 2 includes the effect of a variable volume of 20 nm Au NPs in a variable volume of SF up to 100 μL in a plastic pouch at a constant microwave power (10 W) for 30 s. Paradigm 3 includes the effect of constant microwave power (10 W) and microwave heating time (30 s), constant volume of Au NPs (100 μL), and variable size of Au NPs (20-200 nm) placed in a plastic pouch through a synthetic skin patch. In these experiments, an average of 60-100% reduction in the size of an l-alanine crystal (initial size = 450 μm) without damage to the synthetic skin or increasing the temperature of the samples beyond the physiological range was reported.

  7. Enzymatic resolution for the preparation of enantiomerically enriched D-beta-heterocyclic alanine derivatives using Escherichia coli aromatic L-amino acid transaminase.

    PubMed

    Cho, Byung-Kwan; Park, Hyung-Yeon; Seo, Joo-Hyun; Kinnera, Koteshwar; Lee, Bon-Su; Kim, Byung-Gee

    2004-11-20

    An enzymatic resolution was carried out for the preparation of enriched beta-heterocyclic D-alanine derivatives using Escherichia coli aromatic L-amino acid transaminase. The excess of pyrazole, imidazole, or 1,2,4-triazole reacted with methyl-2-acetamidoacrylate in acetonitrile in the presence of potassium carbonate at 60 degrees C, directly leading to make the potassium salt of the corresponding N-acetyl-beta-heterocyclic alanine derivatives. After the acidic deprotection of the N-acetyl group, 10 mM of racemic pyrazolylalanine, triazolylalanine, and imidazolylalanine were resolved to D-pyrazolylalanine, D-triazolylalanine, and D-imidazolylalanine with 46% (85% ee), 42% (72% ee), and 48% (95% ee) conversion yield in 18 h, respectively, using E. coli aromatic L-amino acid transaminase (EC 2.6.1.5). Although the three beta-heterocyclic L-alanine derivatives have similar molecular structures, they showed different reaction rates and enantioselectivities. The relative reactivities of the transaminase toward the beta-heterocyclic L-alanine derivatives could be explained by the relationship between the substrate binding energy (E, kcal/mol) to the enzyme active site and the distance (delta, A) from the nitrogen of alpha-amino group of the substrates to the C4' carbon of PLP-Lys258 Schiff base. As the ratio of the substrate binding energy (E) to the distance (delta) becomes indicative value of k(cat)/K(M) of the enzyme to the substrate, the relative reactivities of the beta-heterocyclic L-alanine derivatives were successfully correlated with E/delta, and the relationship was confirmed by our experiments.

  8. Analysis of the Effects of a gerP Mutation on the Germination of Spores of Bacillus subtilis

    PubMed Central

    Butzin, Xuan Yi; Troiano, Anthony J.; Coleman, William H.; Griffiths, Keren K.; Doona, Christopher J.; Feeherry, Florence E.; Wang, Guiwen; Li, Yong-qing

    2012-01-01

    As previously reported, gerP Bacillus subtilis spores were defective in nutrient germination triggered via various germinant receptors (GRs), and the defect was eliminated by severe spore coat defects. The gerP spores' GR-dependent germination had a longer lag time between addition of germinants and initiation of rapid release of spores' dipicolinic acid (DPA), but times for release of >90% of DPA from individual spores were identical for wild-type and gerP spores. The gerP spores were also defective in GR-independent germination by DPA with its associated Ca2+ divalent cation (CaDPA) but germinated better than wild-type spores with the GR-independent germinant dodecylamine. The gerP spores exhibited no increased sensitivity to hypochlorite, suggesting that these spores have no significant coat defect. Overexpression of GRs in gerP spores did lead to faster germination via the overexpressed GR, but this was still slower than germination of comparable gerP+ spores. Unlike wild-type spores, for which maximal nutrient germinant concentrations were between 500 μM and 2 mM for l-alanine and ≤10 mM for l-valine, rates of gerP spore germination increased up to between 200 mM and 1 M l-alanine and 100 mM l-valine, and at 1 M l-alanine, the rates of germination of wild-type and gerP spores with or without all alanine racemases were almost identical. A high pressure of 150 MPa that triggers spore germination by activating GRs also triggered germination of wild-type and gerP spores identically. All these results support the suggestion that GerP proteins facilitate access of nutrient germinants to their cognate GRs in spores' inner membrane. PMID:22904285

  9. How stable is a collagen triple helix? An ab initio study on various collagen and beta-sheet forming sequences.

    PubMed

    Pálfi, Villo K; Perczel, András

    2008-07-15

    Collagen forms the well characterized triple helical secondary structure, stabilized by interchain H-bonds. Here we have investigated the stability of fully optimized collagen triple helices and beta-pleated sheets by using first principles (ab initio and DFT) calculations so as to determine the secondary structure preference depending on the amino acid composition. Models composed of a total of 18 amino acid residues were studied at six different amino acid compositions: (i) L-alanine only, (ii) glycine only, (iii) L-alanines and glycine, (iv) L-alanines and D-alanine, (v) L-prolines with glycine, (vi) L-proline, L-hydroxyproline, and glycine. The last two, v and vi, were designed to mimic the core part of collagen. Furthermore, ii, iii, and iv model the binding and/or recognition sites of collagen. Finally, i models the G-->A replacement, rare in collagen. All calculated structures show great resemblance to those determined by X-ray crystallography. Calculated triple helix formation affinities correlate well with experimentally determined stabilities derived from melting point (T(m)) data of different collagen models. The stabilization energy of a collagen triple helical structure over that of a beta-pleated sheet is 2.1 kcal mol(-1) per triplet for the [(-Pro-Hyp-Gly-)(2)](3) collagen peptide. This changes to 4.8 kcal mol(-1) per triplet of destabilization energy for the [(-Ala-Ala-Gly-)(2)](3) sequence, known to be disfavored in collagen. The present study proves that by using first principles methods for calculating stabilities of supramolecular complexes, such as collagen and beta-pleated sheets, one can obtain stability data in full agreement with experimental observations, which envisage the applicability of QM in molecular design.

  10. [Enzymetic synthesis and characterization of a carnosine analogue in non-aqueous solvent].

    PubMed

    Zhou, Xiaohua; Su, Xiali; Lu, Yao

    2009-12-01

    Carnosine (beta-Ala-L-His) has high antioxidant activity, and it is widely used in biology, chemical engineering, medicine and other fields. Its analogue syntheised in non-aqueous solvent and catalyzed by enzymes is high-effective but low-price, so it has great prospect. Here, we synthesized a carnosine analogue imidazole 4(5)-alanylamide-5(4)-carboxylic acid with imidazole-4,5-dicarboxylic acid and L-Alanine as substrates, alpha-chymotrypsin as catalyst in tetrahydrofuran (THF) solvent. Based on the orthogonal experiments, the optimized synthetic conditions are 4,5-dicarboxylic acid: L-alanine = 1:3 (m/m), alpha-chymotrypsin: substrates (4,5-dicarboxyl acid and L-alanine) = 1:200 (m/m), pH 8 phosphate buffer:THF = 1.6:10 (V/V), reaction temperature 35 degrees C, time 1.5 h. We separated the product with silica gel G60 thin-layer chromatography (TLC), and a new spot appeared at Rf (ratio to front) = 0.81; then the new spot was purified and characterized with UV spectra, high performance liquid chromatogram (HPLC) and 13C NMR (13C nuclear magnetic resonance). The UV spectra shows a new absorption peak at 310 nm, and the peak in 253 nm is largely strengthened; HPLC reserve times are all 4.5 min at 253 nm, 310 nm, 330 nm; 13C NMR shows 8 carbons. Combing with the catalytic mechanism of alpha-chymotrypsin, structure of the analogue is confirmed, i.e., imidazole 4(5)-alanylamide-5(4)-carboxylic acid.

  11. Mechanistic and Evolutionary Insights from the Reciprocal Promiscuity of Two Pyridoxal Phosphate-dependent Enzymes*

    PubMed Central

    Soo, Valerie W. C.; Yosaatmadja, Yuliana; Squire, Christopher J.

    2016-01-01

    Enzymes that utilize the cofactor pyridoxal 5′-phosphate play essential roles in amino acid metabolism in all organisms. The cofactor is used by proteins that adopt at least five different folds, which raises questions about the evolutionary processes that might explain the observed distribution of functions among folds. In this study, we show that a representative of fold type III, the Escherichia coli alanine racemase (ALR), is a promiscuous cystathionine β-lyase (CBL). Furthermore, E. coli CBL (fold type I) is a promiscuous alanine racemase. A single round of error-prone PCR and selection yielded variant ALR(Y274F), which catalyzes cystathionine β-elimination with a near-native Michaelis constant (Km = 3.3 mm) but a poor turnover number (kcat ≈10 h−1). In contrast, directed evolution also yielded CBL(P113S), which catalyzes l-alanine racemization with a poor Km (58 mm) but a high kcat (22 s−1). The structures of both variants were solved in the presence and absence of the l-alanine analogue, (R)-1-aminoethylphosphonic acid. As expected, the ALR active site was enlarged by the Y274F substitution, allowing better access for cystathionine. More surprisingly, the favorable kinetic parameters of CBL(P113S) appear to result from optimizing the pKa of Tyr-111, which acts as the catalytic acid during l-alanine racemization. Our data emphasize the short mutational routes between the functions of pyridoxal 5′-phosphate-dependent enzymes, regardless of whether or not they share the same fold. Thus, they confound the prevailing model of enzyme evolution, which predicts that overlapping patterns of promiscuity result from sharing a common multifunctional ancestor. PMID:27474741

  12. Metabolic Effects of Insulin and IGFs on Gilthead Sea Bream (Sparus aurata) Muscle Cells

    PubMed Central

    Montserrat, Núria; Capilla, Encarnación; Navarro, Isabel; Gutiérrez, Joaquim

    2012-01-01

    Primary cultures of gilthead sea bream myocytes were performed in order to examine the relative metabolic function of insulin compared with IGF-I and IGF-II (insulin-like growth factors, IGFs) at different stages in the cell culture. In these cells, the in vitro effects of insulin and IGFs on 2-deoxyglucose (2-DG) and l-alanine uptake were studied in both myocytes (day 4) and small myotubes (day 9). 2-DG uptake in gilthead sea bream muscle cells was increased in the presence of insulin and IGFs in a time dependent manner and along with muscle cell differentiation. On the contrary, l-alanine uptake was also stimulated by insulin and IGFs but showed an inverse pattern, being the uptake higher in small myocytes than in large myotubes. The results of preincubation with inhibitors (PD-98059, wortmannin, and cytochalasin B) on 2-DG uptake indicated that insulin and IGFs stimulate glucose uptake through the same mechanisms, and evidenced that mitogenesis activator protein kinase (MAPK) and PI3K–Akt transduction pathways mediate the metabolic function of these peptides. In the same way, we observed that GLUT4 protein synthesis was stimulated in the presence of insulin and IGFs in gilthead sea bream muscle cells in a different manner at days 4 or 9 of the culture. In summary we describe here, for the first time, the effects of insulin and IGFs on 2-DG and l-alanine uptake in primary culture of gilthead sea bream muscle cells. We show that both MAPK and PI3K–Akt transduction pathways are needed in order to control insulin and IGFs actions in these cells. Moreover, changes in glucose uptake can be explained by the action of the GLUT4 transporter, which is stimulated in the presence of insulin and IGFs throughout the cell culture. PMID:22654873

  13. Food color, flavor, and conditioned avoidance among red-winged blackbirds.

    PubMed

    Werner, Scott J; Kimball, Bruce A; Provenza, Frederick D

    2008-01-28

    The relationship between food flavors and postingestive feedback enables mammalian herbivores to procure nutrients and avoid toxins within ever-changing environments. We conducted four experiments with red-winged blackbirds (Agelaius phoeniceus) in captivity to determine the relative roles of color and flavor cues paired with negative postingestive feedback. We first conducted baseline tests to assess preferences for colors and flavors. All blackbirds preferred red- to blue-colored food, and they preferred umami- (l-alanine) flavored to bitter/astringent food (tannic acid). We observed no difference in consumption of salty (NaCl) vs sour (citric acid) foods during baseline tests (i.e., neutral flavors). We then conditioned experimentally naïve blackbirds with intraperitoneal injections of lithium chloride (LiCl) to avoid food treated with red and l-alanine, or red and NaCl (n=30 birds per conditioning group). Subsequent to conditioning with LiCl, three test groups were established from each conditioned group to evaluate color and flavor preferences, and preferences for novel color-flavor pairings (e.g., red/tannic acid vs blue/l-alanine). Blackbirds avoided red and salty food throughout the 4-day test. Avoidance conditioned with LiCl extinguished for preferred flavors, but not for colors, of food. Conditioning affected indifference for the otherwise preferred flavor and avoidance for the otherwise neutral flavor. Relative to the neutral-flavor conditioning group, the group conditioned with a preferred flavor exhibited stronger conditioned avoidance of colored food. Unlike conditioned flavor avoidance, birds were conditioned to avoid red food only when blue food was made familiar prior to conditioning. Collectively, these results illustrate that blackbirds used affective processes (flavor-feedback relationships) to shift preference for both novel and familiar flavors, and cognitive associations (colors) to avoid food, subsequent to toxin exposure. We discuss the

  14. Electron transport and electrochemical proton gradient in membrane vesicles of Clostridium thermoautotrophicum.

    PubMed Central

    Hugenholtz, J; Ljungdahl, L G

    1989-01-01

    Membrane vesicles of Clostridium thermoautotrophicum containing carbon monoxide dehydrogenase generated a proton motive force when exposed to CO. This proton motive force, with a value of -140 mV, consisted of only an electrical potential at pH 7.5 and above and of an electrical potential and pH gradient at a lower pH. The proton motive force drove the uptake of L-alanine by the vesicles to a concentration of 300 times that of the medium. PMID:2708323

  15. Reduced Acid Dissociation of Amino-Acids at the Surface of Water

    PubMed Central

    2017-01-01

    We use surface-specific intensity vibrational sum-frequency generation and attenuated total reflection spectroscopy to probe the ionization state of the amino-acids l-alanine and l-proline at the air/water surface and in the bulk. The ionization state is determined by probing the vibrational signatures of the carboxylic acid group, representing the nondissociated acid form, and the carboxylate anion group, representing the dissociated form, over a wide range of pH values. We find that the carboxylic acid group deprotonates at a significantly higher pH at the surface than in the bulk. PMID:28177623

  16. Analytical protocol for identification of BMAA and DAB in biological samples.

    PubMed

    Spácil, Zdenek; Eriksson, Johan; Jonasson, Sara; Rasmussen, Ulla; Ilag, Leopold L; Bergman, Birgitta

    2010-01-01

    Beta-N-methylamino-L-alanine (BMAA) is a non-protein amino acid, thought to be inflicting neurodegenerative diseases related to ALS/PDC in human beings. Due to conflicting data concerning the presence of BMAA in various biological matrixes, we present a robust and sensitive method for high confidence identification of BMAA after derivatization by 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC). The efficient sample pretreatment in combination with LC-MS/MS SRM enables chromatographic separation of BMAA from the isomer 2,3-diaminobutyric acid (DAB). The method is applicable for selective BMAA/DAB detection in various biological samples ranging from a prokaryotic cyanobacterium to eukaryotic fish.

  17. Effect of static magnetic field on endospore germination.

    PubMed

    Wu, Wen Jie; Liu, Si Li; Yung, Pun To

    2017-02-01

    This work investigated the effect of static magnetic field (SMF) on Bacillus atrophaeus endospore germination. Germination was triggered by L-alanine in 1.3-T SMF and characterized by ion release, Ca(2+) -dipicolinic acid release, and water influx. These events were monitored by electrical conductivity, Tb-DPA fluorescence, and optical density, respectively. Culturability of endospore germinated in SMF exposure was evaluated by CFU enumeration. Results indicated that 1.3-T SMF failed to significantly affect endospore germination and culturability, suggesting that the three aforementioned processes were not sensitive to SMF. Bioelectromagnetics. 38:121-127, 2017. © 2016 Wiley Periodicals, Inc.

  18. DFT calculation analysis of terahertz time-domain spectra of polyalanines

    NASA Astrophysics Data System (ADS)

    Itoh, Koichi; Ikeda, Atuko; Iwamoto, Toshiyuki; Nishizawa, Seizi

    2011-12-01

    Density functional theory (DFT) calculation was applied to simulate the far infrared (far-IR) spectra in the 700-0 cm -1 region of α-helical L-alanine oligomer models with the number of peptide bonds ( n) of 24-8. The simulation for the model with n = 24 is in reasonable agreement with the dichroic IR spectra in the 700-60 cm -1 region already reported [K. Itoh and T. Shimanouchi, Biopolymers 9 (1970) 383], indicating the high reliability of the calculation. Terahertz (THz) time-domain spectroscopy was used to measure the far-IR spectra in the 160 - ca. 5 cm -1 region for poly- L-alanine in powder and film states. On treatment of the α-helical poly- L-alanine film with formic acid for 5 min a parallel band at 127 cm -1 and perpendicular bands at 116 and 82 cm -1 shift to 116, 109 and 73 cm -1, respectively, with concomitant intensity diminution, and on further treatment for 1 h the bands disappear and the far-IR spectrum in the region of 160 - ca. 5 cm -1 becomes almost transparent. On the other hand, the film treated with formic acid for 1 h still gives rise to the amides I and II bands due the α-helical structure with appreciable intensity. The calculated frequencies and intensities of bands corresponding to the observed bands at 127, 116 and 82 cm -1 decrease with decreasing the number of peptides bonds from 24 to 8, suggesting that the observed frequency lowering and intensity diminution are due to the decrease in the average number of the L-alanine residues forming the α-helix. After the treatment for 1 h the average number becomes too small to give the far-IR bands, resulting in the almost transparent spectral feature. The simulation also predicted the appearance of the accordion-like modes of the α-helical rod at 23 ( n = 24), 26.5 ( n = 20), 32 ( n = 16), 39 ( n = 12) and 48.5 cm -1 ( n = 8) and the bending modes at 14 ( n = 24), 19 ( n = 20) and 27 cm -1 ( n = 16). The observation of these modes, which should be called as "collective modes" in the

  19. Reduced Acid Dissociation of Amino-Acids at the Surface of Water.

    PubMed

    Strazdaite, Simona; Meister, Konrad; Bakker, Huib J

    2017-03-15

    We use surface-specific intensity vibrational sum-frequency generation and attenuated total reflection spectroscopy to probe the ionization state of the amino-acids l-alanine and l-proline at the air/water surface and in the bulk. The ionization state is determined by probing the vibrational signatures of the carboxylic acid group, representing the nondissociated acid form, and the carboxylate anion group, representing the dissociated form, over a wide range of pH values. We find that the carboxylic acid group deprotonates at a significantly higher pH at the surface than in the bulk.

  20. Lysis of Escherichia coli by Glycine Is Potentiated by Pyridoxine Starvation

    PubMed Central

    Dempsey, Walter B.

    1973-01-01

    Pyridoxineless mutants of Escherichia coli are lysed in a few hours when starved for pyridoxine in a glucose minimal medium containing glycine at 10 mM. The lysis is prevented equally well by l-alanine and by d-alanine when either is present at 0.1 mM. The lysis is potentiated by 0.5 mM l-methionine. The peculiar susceptibility of E. coli B to glycine-mediated lysis during starvation for pyridoxine suggests that the starvation reduces the availability of some normal antagonist of glycine, presumably alanine. PMID:4583221

  1. The mussel thread cuticle, a biological granular composite coating

    NASA Astrophysics Data System (ADS)

    Holten-Andersen, Niels; Birkedal, Henrik; Lee, Kaa Yee C.; Waite, J. Herbert

    2009-03-01

    The cuticle of mussel byssal threads is a peculiar natural granular composite coating that combines high extensibility with high stiffness and hardness. In this study fluorescence microscopy and elemental analysis were exploited to show that the 3, 4-dihydroxyphenyl-L-alanine (dopa) residues of mussel foot protein-1 co-localize with Fe and Ca distributions in the cuticle of Mytilus galloprovincials mussel byssal threads. Removal of Fe and Ca from the cuticle by chelation results in a 50% reduction in hardness. Dopa-metal complexes may be a significant source of stability as cross-links in the composite cuticles.

  2. Polymerization of amino acids under primitive earth conditions.

    NASA Technical Reports Server (NTRS)

    Flores, J. J.; Ponnamperuma, C.

    1972-01-01

    Small amounts of peptides were obtained when equal amounts of methane and ammonia were reacted with vaporized aqueous solutions of C14-labeled glycine, L-alanine, L-aspartic acid, L-glutamic acid and L-threonine in the presence of a continuous spark discharge in a 24-hr cyclic process. The experiment was designed to demonstrate the possibility of peptide synthesis under simulated primeval earth conditions. It is theorized that some dehydration-condensation processes may have taken place, with ammonium cyanide, the hydrogencyanide tetramer or aminonitriles as intermediate products, during the early chemical evolution of the earth.

  3. Synthesis and characterization of bis-thiourea having amino acid derivatives

    NASA Astrophysics Data System (ADS)

    Fakhar, Imran; Yamin, Bohari M.; Hasbullah, Siti Aishah

    2016-11-01

    In this article four new symmetric bis-thiourea derivatives having amino acid linkers were reported with good yield. Isophthaloyl dichloride was used as spacer and L-alanine, L-aspartic acid, L-phenylalanine and L-glutamic acid were used as linkers. Bis-thiourea derivatives were prepared from relatively stable isophthaloyl isothiocyanate intermediate. Newly synthesized bis-thiourea derivatives were characterized by FTIR, H-NMR, 13C-NMR and CHNS-O elemental analysis techniques. Characterization data was in good agreement with the expected derivatives, hence confirmed the synthesis of four new derivatives of bis-thiourea having amino acids.

  4. Higher plants contain L-asparate oxidase, the first enzyme of the Escherichia coli quinolinate synthetase system.

    PubMed

    Hosokawa, Y; Mitchell, E; Gholson, R K

    1983-02-28

    Cotton callus cells contain an L-aspartate oxidase which does not appear to be active with D-aspartate, L-glutamate or D- or L-alanine. The enzyme requires for activity a dialyzable cofactor with an apparent molecular weight of 1,050. Since L-aspartate oxidase is the first enzyme of the pathway for de novo synthesis of the pyridine ring in Escherichia coli, this finding suggests that higher plants may use the L-aspartate-dihydroxyacetone phosphate pathway for de novo pyridine nucleotide biosynthesis.

  5. A method to assess the bacterial content of refrigerated meat.

    PubMed Central

    Perez de Castro, B; Asensio, M A; Sanz, B; Ordoñez, J A

    1988-01-01

    A new method has been developed to estimate the levels of gram-negative bacteria on refrigerated meat. The method is based on the aminopeptidase activity of these bacteria, which cleaves L-alanine-p-nitroanilide to yield p-nitroaniline, which is easily determined spectrophotometrically. This method allows the determination of levels around 10(6) to 10(7) CFU cm-2 in about 3 h. Because of the yellow color of p-nitroaniline, bacterial loads around 10(7) CFU cm-2 develop a color intense enough to be detected with the naked eye. PMID:3415222

  6. Inorganic nitrogen assimilation by the photosynthetic bacterium Rhodopseudomonas capsulata.

    PubMed Central

    Johansson, B C; Gest, H

    1976-01-01

    The photosynthetic bacterium Rhodopseudomonas capsulata lacks glutamate dehydrogenase and normally uses the glutamine synthetase/glutamate synthase sequence of reactions for assimilation of N2 and ammonia. The glutamine synthetase in cell-free extracts of the organism is completely sedimented by centrifugation at 140,000 X g for 2 h, is inhibited by L-alanine but not by adenosine 5'-monophosphate, and exhibits two apparent Km values for ammonia (ca. 13 muM and 1 mM). PMID:10281

  7. Alpha-helical hydrophobic polypeptides form proton-selective channels in lipid bilayers

    NASA Technical Reports Server (NTRS)

    Oliver, A. E.; Deamer, D. W.

    1994-01-01

    Proton translocation is important in membrane-mediated processes such as ATP-dependent proton pumps, ATP synthesis, bacteriorhodopsin, and cytochrome oxidase function. The fundamental mechanism, however, is poorly understood. To test the theoretical possibility that bundles of hydrophobic alpha-helices could provide a low energy pathway for ion translocation through the lipid bilayer, polyamino acids were incorporated into extruded liposomes and planar lipid membranes, and proton translocation was measured. Liposomes with incorporated long-chain poly-L-alanine or poly-L-leucine were found to have proton permeability coefficients 5 to 7 times greater than control liposomes, whereas short-chain polyamino acids had relatively little effect. Potassium permeability was not increased markedly by any of the polyamino acids tested. Analytical thin layer chromatography measurements of lipid content and a fluorescamine assay for amino acids showed that there were approximately 135 polyleucine or 65 polyalanine molecules associated with each liposome. Fourier transform infrared spectroscopy indicated that a major fraction of the long-chain hydrophobic peptides existed in an alpha-helical conformation. Single-channel recording in both 0.1 N HCl and 0.1 M KCl was also used to determine whether proton-conducting channels formed in planar lipid membranes (phosphatidylcholine/phosphatidylethanolamine, 1:1). Poly-L-leucine and poly-L-alanine in HCl caused a 10- to 30-fold increase in frequency of conductive events compared to that seen in KCl or by the other polyamino acids in either solution. This finding correlates well with the liposome observations in which these two polyamino acids caused the largest increase in membrane proton permeability but had little effect on potassium permeability. Poly-L-leucine was considerably more conductive than poly-L-alanine due primarily to larger event amplitudes and, to a lesser extent, a higher event frequency. Poly-L-leucine caused two

  8. Biosynthesis of pyrrolnitrin. Incorporation of 13C, 15N double-labelled D- and L-tryptophan.

    PubMed

    Zhou, P; Mocek, U; Siesel, B; Floss, H G

    1992-01-01

    Experiments on the incorporation of D- and L-[alanine-3-13C,2-15N]tryptophan into the antibiotic pyrrolnitrin in Pseudomonas aureofaciens confirmed earlier conclusions about the conversion of L-tryptophan into pyrrolnitrin. They also demonstrated that a fraction of the D isomer is incorporated without breakage of the 15N-carbon bond, consistent with the operation of a second pathway from D-tryptophan to pyrrolnitrin. Cell-free experiments confirmed the conversion of 3-(o-aminophenyl)pyrrole into aminopyrrolnitrin but failed to detect enzymatic oxidation of the latter to pyrrolnitrin.

  9. Growth and study of triglycine sulfate (TGS) crystals in low-G for infrared detector applications

    NASA Technical Reports Server (NTRS)

    Lal, R. B.; Batra, A. K.; Aggarwal, M. D.; Wilcox, W. R.; Trolinger, J. D.

    1991-01-01

    Experiments on growth of TGS crystals using (010) and (001) oriented disc shape seeds in the low gravity environment aboard Spacelab-3 are presented. The holographic interferograms reconstructed on the ground demonstrated diffusion limited growth. The morphology of the crystals grown was similar to that of crystals grown on earth, except the faces were not fully developed and planar. The device quality of these crytals is considered to be comparable with the best crystals grown on earth. Better infrared detector characteristics were obtained by doping TGS with Cs and L-alanine simultaneously on the ground. Crystals grown on (010) poled seeds show improved morphology and pyroelectric properties.

  10. Amplification of Diverse Catalytic Properties of Evolving Molecules in a Simulated Hydrothermal Environment

    NASA Astrophysics Data System (ADS)

    Yokoyama, Shinnosuke; Koyama, Akihiro; Nemoto, Atsushi; Honda, Hajime; Imai, Ei-Ichi; Hatori, Kuniyuki; Matsuno, Koichiro

    2003-12-01

    We observed chemical evolution in a mixture of four amino acids, glycine, L-alanine, L-valine and L-aspartic acid, circulated through a flow reactor simulating the thermodynamic conditions of a hydrothermal environment. These monomers form peptides with tertiary structures and potential catalytic functions. The HPLC profile of synthesized oligomers varied with each particular run, but the products were found to separate into distinct clusters when more than one hundred runs were compared statistically. This observation suggests that chemical evolution on the early Earth had stochastic aspects that must be understood in order to develop useful models of prebiotic evolution.

  11. Neurotoxic flying foxes as dietary items for the Chamorro people, Marianas Islands.

    PubMed

    Banack, Sandra Anne; Murch, Susan J; Cox, Paul Alan

    2006-06-15

    Fanihi -- flying foxes (Pteropus mariannus mariannus, Pteropodidae) -- are a highly salient component of the traditional Chamorro diet. A neurotoxic, non-protein amino acid, beta-methylamino-l-alanine (BMAA) accumulates in flying foxes, which forage on the seeds of Cycas micronesica (Cycadaceae) in Guam's forests. BMAA occurs throughout flying fox tissues both as a free amino acid and in a protein-bound form. It is not destroyed by cooking. Protein-bound BMAA also remains in cycad flour which has been washed and prepared by the Chamorro people as tortillas, dumplings, and thickened soups. Other animals that forage on cycad seeds may also provide BMAA inputs into the traditional Chamorro diet.

  12. The Effects of the Toxic Cyanobacterium Limnothrix (Strain AC0243) on Bufo marinus Larvae

    PubMed Central

    Daniels, Olivia; Fabbro, Larelle; Makiela, Sandrine

    2014-01-01

    Limnothrix (strain AC0243) is a cyanobacterium, which has only recently been identified as toxin producing. Under laboratory conditions, Bufo marinus larvae were exposed to 100,000 cells mL−1 of Limnothrix (strain AC0243) live cultures for seven days. Histological examinations were conducted post mortem and revealed damage to the notochord, eyes, brain, liver, kidney, pancreas, gastrointestinal tract, and heart. The histopathological results highlight the toxicological impact of this strain, particularly during developmental stages. Toxicological similarities to β-N-Methylamino-l-alanine are discussed. PMID:24662524

  13. Midbrain dopamine function in schizophrenia and depression: a post-mortem and positron emission tomographic imaging study.

    PubMed

    Howes, Oliver D; Williams, Matthew; Ibrahim, Kemal; Leung, Garret; Egerton, Alice; McGuire, Philip K; Turkheimer, Federico

    2013-11-01

    Elevated in vivo markers of presynaptic striatal dopamine activity have been a consistent finding in schizophrenia, and include a large effect size elevation in dopamine synthesis capacity. However, it is not known if the dopaminergic dysfunction is limited to the striatal terminals of dopamine neurons, or is also evident in the dopamine neuron cell bodies, which mostly originate in the substantia nigra. The aim of our studies was therefore to determine whether dopamine synthesis capacity is altered in the substantia nigra of people with schizophrenia, and how this relates to symptoms. In a post-mortem study, a semi-quantitative analysis of tyrosine hydroxylase staining was conducted in nigral dopaminergic cells from post-mortem tissue from patients with schizophrenia (n = 12), major depressive disorder (n = 13) and matched control subjects (n = 13). In an in vivo imaging study, nigral and striatal dopaminergic function was measured in patients with schizophrenia (n = 29) and matched healthy control subjects (n = 29) using (18)F-dihydroxyphenyl-L-alanine ((18)F-DOPA) positron emission tomography. In the post-mortem study we found that tyrosine hydroxylase staining was significantly increased in nigral dopaminergic neurons in schizophrenia compared with both control subjects (P < 0.001) and major depressive disorder (P < 0.001). There was no significant difference in tyrosine hydroxylase staining between control subjects and patients with major depressive disorder, indicating that the elevation in schizophrenia is not a non-specific indicator of psychiatric illness. In the in vivo imaging study we found that (18)F-dihydroxyphenyl-L-alanine uptake was elevated in both the substantia nigra and in the striatum of patients with schizophrenia (effect sizes = 0.85, P = 0.003 and 1.14, P < 0.0001, respectively) and, in the voxel-based analysis, was elevated in the right nigra (P < 0.05 corrected for family wise-error). Furthermore, nigral (18)F-dihydroxyphenyl-L-alanine

  14. Heteronuclear dipolar recoupling in multiple-spin system under fast magic-angle spinning.

    PubMed

    Chou, Fang-Chieh; Huang, Shing-Jong; Chan, Jerry C C

    2009-03-01

    We show that the C-REDOR sequence can be modified according to the framework of rotary-REDOR to realize heteronuclear recoupling in multiple-spin systems. Because of the inherent favorable properties of C-REDOR with respect to rf inhomogeneity, our approach is anticipated to find useful applications in biological research. Furthermore, active rotor synchronization of the windowless C-REDOR is implemented by an ad hoc shortening of the pulse elements. Numerical simulations and experiments measured for [U-(13)C,(15)N]-L-alanine are used to validate our approach.

  15. Alpha-helical hydrophobic polypeptides form proton-selective channels in lipid bilayers

    NASA Technical Reports Server (NTRS)

    Oliver, A. E.; Deamer, D. W.

    1994-01-01

    Proton translocation is important in membrane-mediated processes such as ATP-dependent proton pumps, ATP synthesis, bacteriorhodopsin, and cytochrome oxidase function. The fundamental mechanism, however, is poorly understood. To test the theoretical possibility that bundles of hydrophobic alpha-helices could provide a low energy pathway for ion translocation through the lipid bilayer, polyamino acids were incorporated into extruded liposomes and planar lipid membranes, and proton translocation was measured. Liposomes with incorporated long-chain poly-L-alanine or poly-L-leucine were found to have proton permeability coefficients 5 to 7 times greater than control liposomes, whereas short-chain polyamino acids had relatively little effect. Potassium permeability was not increased markedly by any of the polyamino acids tested. Analytical thin layer chromatography measurements of lipid content and a fluorescamine assay for amino acids showed that there were approximately 135 polyleucine or 65 polyalanine molecules associated with each liposome. Fourier transform infrared spectroscopy indicated that a major fraction of the long-chain hydrophobic peptides existed in an alpha-helical conformation. Single-channel recording in both 0.1 N HCl and 0.1 M KCl was also used to determine whether proton-conducting channels formed in planar lipid membranes (phosphatidylcholine/phosphatidylethanolamine, 1:1). Poly-L-leucine and poly-L-alanine in HCl caused a 10- to 30-fold increase in frequency of conductive events compared to that seen in KCl or by the other polyamino acids in either solution. This finding correlates well with the liposome observations in which these two polyamino acids caused the largest increase in membrane proton permeability but had little effect on potassium permeability. Poly-L-leucine was considerably more conductive than poly-L-alanine due primarily to larger event amplitudes and, to a lesser extent, a higher event frequency. Poly-L-leucine caused two

  16. The phenylthiourea is a competitive inhibitor of the enzymatic oxidation of DOPA by phenoloxidase.

    PubMed

    Ryazanova, Alexandra D; Alekseev, Alexander A; Slepneva, Irina A

    2012-02-01

    Phenoloxidase is a key enzyme of melanization catalyzing the oxidation of phenols. Phenylthiourea (PTU) is the well-known and widely used inhibitor of phenoloxidase. However, the mechanism of its action is not quite clear. In the present work, the effect of PTU on the enzymatic oxidation of 3-(3,4-dihydroxyphenyl)-l-alanine (DOPA) by phenoloxidase was studied by spectrophotometric methods. The inhibition constant of PTU was estimated as 0.21 ± 0.09 µM and the competitive type of inhibition was determined for this reaction.

  17. Altered Muscle Metabolism in Rats After Thermal Injury

    DTIC Science & Technology

    1982-12-01

    by Herndon et a-ketoglutarate. 600 mM L -alanine, 0.18 mM NADH. 1.2 U/ml al." Briefly, this procedure consists of anesthetizing the rat (50 mg lactate...whole homogenates of the gastrocnemius muscle 9 sec and the abdomen for 3 sec in 980C water. Saline (20 ml) was to oxidize pyruvate- l -"C to "CO, was...the same time Econofluor (New England Nuclear, Boston. Mass.) and 10% metha- of day. nol. Oleate- l -’C oxidation rates by whole gastrocnemius homoge

  18. Polymerization of amino acids under primitive earth conditions.

    NASA Technical Reports Server (NTRS)

    Flores, J. J.; Ponnamperuma, C.

    1972-01-01

    Small amounts of peptides were obtained when equal amounts of methane and ammonia were reacted with vaporized aqueous solutions of C14-labeled glycine, L-alanine, L-aspartic acid, L-glutamic acid and L-threonine in the presence of a continuous spark discharge in a 24-hr cyclic process. The experiment was designed to demonstrate the possibility of peptide synthesis under simulated primeval earth conditions. It is theorized that some dehydration-condensation processes may have taken place, with ammonium cyanide, the hydrogencyanide tetramer or aminonitriles as intermediate products, during the early chemical evolution of the earth.

  19. Oral Delivery of Propofol with Methoxymethylphosphonic Acid as the Delivery Vehicle.

    PubMed

    Wei, Yonggang; Qiu, Guanpeng; Lei, Bailin; Qin, Linlin; Chu, Hongzhu; Lu, Yonghua; Zhu, Guozhi; Gao, Qiu; Huang, Qingping; Qian, Guofei; Liao, Pengfei; Luo, Xinfeng; Zhang, Xiaowei; Zhang, Chen; Li, Yao; Zheng, Suxin; Yu, Yan; Tang, Pingming; Ni, Jia; Yan, Pangke; Zhou, Yi; Li, Pan; Huang, Xia; Gong, Aisheng; Liu, Jianyu

    2017-10-12

    Phosphonamidate 3a of methoxymethylphosphonic acid (MMPA) with propofol (1) and l-alanine ethyl ester was found to be an efficient scaffold for the oral delivery of compound 1. The synthesis and evaluation of MMPA based phosphonamidates of compound 1, HSK3486 (2), and other phenolic drugs revealed the general application of MMPA as the effective delivery vehicle for phenolic drugs. On the basis of plasma concentrations of compound 1 and SN38 (14), the oral bioavailability of compound 3a and 15 in beagle dogs was found to be 97.6% and 34.1%, respectively.

  20. Role of Lipotropes in Mammary Carcinogenesis.

    DTIC Science & Technology

    1997-09-01

    6 1. Experimental M ethods ......................................... 6 2. R esults...Pyridoxine HC1 0.022 Calcium phosphate, 4.5 Riboflavin 0.022 dibasic L -Alanine 3.5 Thiamine HC1 0.022 L -Arginine HC1 12.1 Glycine 23.3 L -Asparagine 6.0 L ...histidine HC1.H 20 4.5 L -Aspartic acid 3.5 L -isoleucine 8.2 L -Cystine 3.5 L -leucine 11.1 L -Glutamic acid 40.0 L -lysine HC1 18.0 Mineral mix, 35.0 L

  1. Growth and study of triglycine sulfate (TGS) crystals in low-G for infrared detector applications

    NASA Technical Reports Server (NTRS)

    Lal, R. B.; Batra, A. K.; Aggarwal, M. D.; Wilcox, W. R.; Trolinger, J. D.

    1991-01-01

    Experiments on growth of TGS crystals using (010) and (001) oriented disc shape seeds in the low gravity environment aboard Spacelab-3 are presented. The holographic interferograms reconstructed on the ground demonstrated diffusion limited growth. The morphology of the crystals grown was similar to that of crystals grown on earth, except the faces were not fully developed and planar. The device quality of these crytals is considered to be comparable with the best crystals grown on earth. Better infrared detector characteristics were obtained by doping TGS with Cs and L-alanine simultaneously on the ground. Crystals grown on (010) poled seeds show improved morphology and pyroelectric properties.

  2. Decrystallization of Crystals Using Gold "Nano-Bullets" and the Metal-Assisted and Microwave-Accelerated Decrystallization Technique.

    PubMed

    Thompson, Nishone; Boone-Kukoyi, Zainab; Shortt, Raquel; Lansiquot, Carisse; Kioko, Bridgit; Bonyi, Enock; Toker, Salih; Ozturk, Birol; Aslan, Kadir

    2016-10-18

    Gout is caused by the overproduction of uric acid and the inefficient metabolism of dietary purines in humans. Current treatments of gout, which include anti-inflammatory drugs, cyclooxygenase-2 inhibitors, and systemic glucocorticoids, have harmful side-effects. Our research laboratory has recently introduced an innovative approach for the decrystallization of biological and chemical crystals using the Metal-Assisted and Microwave-Accelerated Evaporative Decrystallization (MAMAD) technique. In the MAMAD technique, microwave energy is used to heat and activate gold nanoparticles that behave as "nano-bullets" to rapidly disrupt the crystal structure of biological crystals placed on planar surfaces. In this study, crystals of various sizes and compositions were studied as models for tophaceous gout at different stages (i.e., uric acid as small crystals (~10-100 μm) and l-alanine as medium (~300 μm) and large crystals (~4400 μm). Our results showed that the use of the MAMAD technique resulted in the reduction of the size and number of uric acid and l-alanine crystals up to >40% when exposed to intermittent microwave heating (up to 20 W power at 8 GHz) in the presence of 20 nm gold nanoparticles up to 120 s. This study demonstrates that the MAMAD technique can be potentially used as an alternative therapeutic method for the treatment of gout by effective decrystallization of large crystals, similar in size to those that often occur in gout.

  3. Decrystallization of Crystals Using Gold “Nano-Bullets” and the Metal-Assisted and Microwave-Accelerated Decrystallization Technique

    PubMed Central

    Thompson, Nishone; Boone-Kukoyi, Zainab; Shortt, Raquel; Lansiquot, Carisse; Kioko, Bridgit; Bonyi, Enock; Toker, Salih; Ozturk, Birol; Aslan, Kadir

    2017-01-01

    Gout is caused by the overproduction of uric acid and the inefficient metabolism of dietary purines in humans. Current treatments of gout, which include anti-inflammatory drugs, cyclooxygenase-2 inhibitors, and systemic glucocorticoids, have harmful side-effects. Our research laboratory has recently introduced an innovative approach for the decrystallization of biological and chemical crystals using the Metal-Assisted and Microwave-Accelerated Evaporative Decrystallization (MAMAD) technique. In the MAMAD technique, microwave energy is used to heat and activate gold nanoparticles that behave as “nano-bullets” to rapidly disrupt the crystal structure of biological crystals placed on planar surfaces. In this study, crystals of various sizes and compositions were studied as models for tophaceous gout at different stages (i.e., uric acid as small crystals (~10–100 μm) and L-alanine as medium (~300 μm) and large crystals (~4400 μm). Our results showed that the use of the MAMAD technique resulted in the reduction of the size and number of uric acid and L-alanine crystals up to >40% when exposed to intermittent microwave heating (up to 20 W power at 8 GHz) in the presence of 20 nm gold nanoparticles up to 120 s. This study demonstrates that the MAMAD technique can be potentially used as an alternative therapeutic method for the treatment of gout by effective decrystallization of large crystals, similar in size to those that often occur in gout. PMID:27763557

  4. Detection of Cyanotoxins in Algae Dietary Supplements

    PubMed Central

    Roy-Lachapelle, Audrey; Solliec, Morgan; Bouchard, Maryse F.; Sauvé, Sébastien

    2017-01-01

    Algae dietary supplements are marketed worldwide as natural health products. Although their proprieties have been claimed as beneficial to improve overall health, there have been several previous reports of contamination by cyanotoxins. These products generally contain non-toxic cyanobacteria, but the methods of cultivation in natural waters without appropriate quality controls allow contamination by toxin producer species present in the natural environment. In this study, we investigated the presence of total microcystins, seven individual microcystins (RR, YR, LR, LA, LY, LW, LF), anatoxin-a, dihydroanatoxin-a, epoxyanatoxin-a, cylindrospermopsin, saxitoxin, and β-methylamino-l-alanine in 18 different commercially available products containing Spirulina or Aphanizomenon flos-aquae. Total microcystins analysis was accomplished using a Lemieux oxidation and a chemical derivatization using dansyl chloride was needed for the simultaneous analysis of cylindrospermopsin, saxitoxin, and β-methylamino-l-alanine. Moreover, the use of laser diode thermal desorption (LDTD) and ultra-high performance liquid chromatography (UHPLC) both coupled to high resolution mass spectrometry (HRMS) enabled high performance detection and quantitation. Out of the 18 products analyzed, 8 contained some cyanotoxins at levels exceeding the tolerable daily intake values. The presence of cyanotoxins in these algal dietary supplements reinforces the need for a better quality control as well as consumer’s awareness on the potential risks associated with the consumption of these supplements. PMID:28245621

  5. Identification of a Vibrio cholerae chemoreceptor that senses taurine and amino acids as attractants

    PubMed Central

    Nishiyama, So-ichiro; Takahashi, Yohei; Yamamoto, Kentaro; Suzuki, Daisuke; Itoh, Yasuaki; Sumita, Kazumasa; Uchida, Yumiko; Homma, Michio; Imada, Katsumi; Kawagishi, Ikuro

    2016-01-01

    Vibrio cholerae, the etiological agent of cholera, was found to be attracted by taurine (2-aminoethanesulfonic acid), a major constituent of human bile. Mlp37, the closest homolog of the previously identified amino acid chemoreceptor Mlp24, was found to mediate taxis to taurine as well as L-serine, L-alanine, L-arginine, and other amino acids. Methylation of Mlp37 was enhanced upon the addition of taurine and amino acids. Isothermal titration calorimetry demonstrated that a purified periplasmic fragment of Mlp37 binds directly to taurine, L-serine, L-alanine and L-arginine. Crystal structures of the periplamic domain of Mlp37 revealed that L-serine and taurine bind to the membrane-distal PAS domain in essentially in the same way. The structural information was supported by characterising the in vivo properties of alanine-substituted mutant forms of Mlp37. The fact that the ligand-binding domain of the L-serine complex had a small opening, which would accommodate a larger R group, accounts for the broad ligand specificity of Mlp37 and allowed us to visualise ligand binding to Mlp37 with fluorescently labelled L-serine. Taken together, we conclude that Mlp37 serves as the major chemoreceptor for taurine and various amino acids. PMID:26878914

  6. A serendipitous discovery of antifreeze protein-specific activity in C-linked antifreeze glycoprotein analogs.

    PubMed

    Eniade, Adewale; Purushotham, Madhusudhan; Ben, Robert N; Wang, J B; Horwath, Kathleen

    2003-01-01

    Structurally diverse carbon-linked (C-linked) analogs of antifreeze glycoprotein (AFGP) have been prepared via linear or convergent solid phase synthesis. These analogs range in molecular weight from approx 1.5-4.1 KDa and do not possess the beta-D-galactose-1,3-alpha-D-N-acetylgalactosamine carbohydrate moiety or the L-threonine-L-alanine-L-alanine polypeptide backbone native to the AFGP wild-type. Despite these dramatic structural modifications, the 2.7-KDa and 4.1-KDa analogs possess antifreeze protein-specific activity as determined by recrystallization-inhibition (RI) and thermal hysteresis (TH) assays. These analogs are weaker than the wild-type in their activity, but nanoliter osmometry indicates that these compounds are binding to ice and affecting a localized freezing point depression. This is the first example of a C-linked AFGP analog that possesses TH and RI activity and suggests that the rational design and synthesis of chemically and biologically stable AFGP analogs is a feasible and worthwhile endeavor. Given the low degree of TH activity, these compounds may prove useful for the protection of cells during freezing and thawing cycles.

  7. delta-Aminolevulinic acid formation. Purification and properties of alanine:4,5-dioxovalerate, aminotransferase and isolation of 4,5-dioxovalerate from Clostridium tetanomorphum.

    PubMed

    Bajkowski, A S; Friedmann, H C

    1982-03-10

    L-Alanine:4,5-dioxovalerate aminotransferase, the enzyme that catalyzes the transamination between alanine and 4,5-dioxovalerate to yield delta-aminolevulinate and pyruvate, has been purified from extracts Clostridium tetanomorphum by acetone precipitation and successive tetanomorphum by acetone precipitation and successive chromatography on Sephadex G-150, hydroxyapatite, Octyl-Sepharose, and SP-Sephadex C-50. The enzyme is pure by the criterion of disc gel electrophoresis with varying polyacrylamide concentrations. It is dimeric, and has an apparent molecular weight of 111,000. Each molecule contains 2 molecules of pyridoxal 5-phosphate. The apparent Km values for 4,5-dioxovalerate and L-alanine are 0.26 and 1.96 mM, respectively. In addition to alanine, glutamate also is an effective amino group donor. The enzyme is inhibited by various keto acids as well as by inhibitors of pyridoxal phosphate-containing enzymes. It was possible to show that 4,5-dioxovalerate is formed by cultures of C. tetanomorphum when grown in the presence of 0.2 M levulinate, an inhibitor of 5-aminolevulinate dehydratase.

  8. Functional analysis of all aminotransferase proteins inferred from the genome sequence of Corynebacterium glutamicum.

    PubMed

    Marienhagen, Jan; Kennerknecht, Nicole; Sahm, Hermann; Eggeling, Lothar

    2005-11-01

    Twenty putative aminotransferase (AT) proteins of Corynebacterium glutamicum, or rather pyridoxal-5'-phosphate (PLP)-dependent enzymes, were isolated and assayed among others with L-glutamate, L-aspartate, and L-alanine as amino donors and a number of 2-oxo-acids as amino acceptors. One outstanding AT identified is AlaT, which has a broad amino donor specificity utilizing (in the order of preference) L-glutamate > 2-aminobutyrate > L-aspartate with pyruvate as acceptor. Another AT is AvtA, which utilizes L-alanine to aminate 2-oxo-isovalerate, the L-valine precursor, and 2-oxo-butyrate. A second AT active with the L-valine precursor and that of the other two branched-chain amino acids, too, is IlvE, and both enzyme activities overlap partially in vivo, as demonstrated by the analysis of deletion mutants. Also identified was AroT, the aromatic AT, and this and IlvE were shown to have comparable activities with phenylpyruvate, thus demonstrating the relevance of both ATs for L-phenylalanine synthesis. We also assessed the activity of two PLP-containing cysteine desulfurases, supplying a persulfide intermediate. One of them is SufS, which assists in the sulfur transfer pathway for the Fe-S cluster assembly. Together with the identification of further ATs and the additional analysis of deletion mutants, this results in an overview of the ATs within an organism that may not have been achieved thus far.

  9. Amino Acid Transport in Mycobacterium smegmatis

    PubMed Central

    Yabu, Kunihiko

    1970-01-01

    The transport of d-alanine, d-glutamic acid, and d-valine in Mycobacterium smegmatis was compared quantitatively with that of their l-isomers. It appeared that the uptake of d-alanine was mediated by an active process displaying saturation kinetics characteristic of enzyme function, whereas the uptake of d-glutamic acid was accomplished by a passive process showing diffusion kinetics. Both processes were involved in the uptake of l-alanine, l-glutamic acid, d-valine, and l-valine. d-Valine competed with l-valine for entry into the cell through a single active process. d-Alanine and l-alanine also utilized the same active process, but the d-isomer could not enter the cell through the passive process. The passive process exhibited characteristics of diffusion, but was sensitive to sulfhydryl-blocking reagents and showed competition among structurally related amino acids. These last findings suggested that the passive process is a facilitated diffusion. PMID:5437732

  10. Antifungal activity of DNA-lipid complexes and DNA-lipid films against Candida species.

    PubMed

    Inoue, Y; Fukushima, T; Hayakawa, T; Ogura, R; Kaminishi, H; Miyazaki, K; Okahata, Y

    2006-01-01

    In this study amphiphilic lipids, DNA-lipid complexes, and DNA-lipid films were prepared, and their antifungal activity against Candida species was examined. The amphiphilic lipids were synthesized from a reaction of glycine or L-alanine with n-alkyl alcohol in the presence of p-toluene sulfonic acid. DNA-lipid complexes, which were prepared by the simple mixing of DNA and amphiphilic lipids, were insoluble in water. Self-standing, water-insoluble DNA-lipid films were prepared by casting the DNA-lipid complexes from a chloroform/ethanol solution. The antifungal activities of the lipids and DNA-lipid complexes against the Candida species were evaluated by minimum inhibitory concentrations (MICs); those of DNA-lipid films were evaluated by the disk diffusion method. The seven kinds of lipids, DNA-lipid complexes, and DNA-lipid films showed antifungal activity, and no differences were seen in the antifungal activities between glycine and L-alanine derivatives. The lipids, DNA-lipid complexes, and DNA-lipid films, which have shorter alkyl chain length in lipids, showed antifungal activity against all Candida species. However, the effect of antifungal activity against Candida species decreased with increased alkyl chain length in lipids. In this study, it was found that lipids, DNA-lipid complexes, and films with a decyl or dodecyl group exhibit more favorable antifungal activity. (c) 2005 Wiley Periodicals, Inc

  11. Equilibria and absorption spectra of tryptophanase.

    PubMed

    Metzler, C M; Viswanath, R; Metzler, D E

    1991-05-25

    Tryptophanase (tryptophan: indole-lyase) from Escherichia coli has been isolated in the holoenzyme form and its absorption spectra and acid-base chemistry have been reevaluated. Apoenzyme has been prepared by dialysis against sodium phosphate and L-alanine and molar absorptivities of the coenzyme bands have been estimated by readdition of pyridoxal 5'-phosphate. The spectrophotometric titration curve, whose midpoint is at pH 7.6 in 0.1 M potassium phosphate buffers, indicates some degree of cooperativity in dissociation of a pair of protons. Resolution of the computed spectra of individual ionic forms of the enzyme with lognormal distribution curves shows that band shapes are similar to those of model Schiff bases and of aspartate aminotransferase. Using molar areas from the latter we estimated amounts of individual tautomeric species. In addition to ketoenamine and enolimine or covalent adduct the high pH form also appears to contain approximately 18% of a species with a dipolar ionic ring (protonated on the ring nitrogen and with phenolate -O-). We suggest that this may be the catalytically active form of the coenzyme in tryptophanase. The equilibrium between tryptophanase and L-alanine has also been reevaluated.

  12. Temperature effects in first-principles solid state calculations of the chemical shielding tensor made simple

    SciTech Connect

    Monserrat, Bartomeu Needs, Richard J.; Pickard, Chris J.

    2014-10-07

    We study the effects of atomic vibrations on the solid-state chemical shielding tensor using first principles density functional theory calculations. At the harmonic level, we use a Monte Carlo method and a perturbative expansion. The Monte Carlo method is accurate but computationally expensive, while the perturbative method is computationally more efficient, but approximate. We find excellent agreement between the two methods for both the isotropic shift and the shielding anisotropy. The effects of zero-point quantum mechanical nuclear motion are important up to relatively high temperatures: at 500 K they still represent about half of the overall vibrational contribution. We also investigate the effects of anharmonic vibrations, finding that their contribution to the zero-point correction to the chemical shielding tensor is small. We exemplify these ideas using magnesium oxide and the molecular crystals L-alanine and β-aspartyl-L-alanine. We therefore propose as the method of choice to incorporate the effects of temperature in solid state chemical shielding tensor calculations using the perturbative expansion within the harmonic approximation. This approach is accurate and requires a computational effort that is about an order of magnitude smaller than that of dynamical or Monte Carlo approaches, so these effects might be routinely accounted for.

  13. The antineoplastic effect of carnosine is accompanied by induction of PDK4 and can be mimicked by L-histidine.

    PubMed

    Letzien, Ulrike; Oppermann, Henry; Meixensberger, Jürgen; Gaunitz, Frank

    2014-04-01

    Carnosine (β-alanyl-L-histidine) is a naturally occurring dipeptide that shows antineoplastic effects in cell culture as well as in animal experiments. Since its mode of action and the targets at the molecular level have not yet been elucidated, we performed qRT-PCR experiments with RNA isolated from glioblastoma cell lines treated with carnosine, β-alanine, L-alanine, L-histidine and the dipeptide L-alanine-L-histidine. The experiments identified a strong induction of expression of the gene encoding pyruvate dehydrogenase 4 (PDK4) under the influence of carnosine and L-histidine, but not by the other substances employed. In addition, inhibition of cell viability was only detected in cells treated with carnosine and L-histidine, with the latter showing a significantly stronger effect than carnosine. Since the tumor cells expressed the tissue form of carnosinase (CN2) but almost no serum carnosinase (CN1), we conclude that cleavage by CN2 is a prerequisite for the antineoplastic effect of carnosine. In addition, enhanced expression of PDK4 under the influence of carnosine/L-histidine opens a new perspective for the interpretation of the ergogenic potential of dietary β-alanine supplementation and adds a new contribution to a growing body of evidence that single amino acids can regulate key metabolic pathways important in health and disease.

  14. A Better Understanding of Protein Structure and Function by the Synthesis and Incorporation of Selenium- and Tellurium Containing Tryptophan Analogs

    SciTech Connect

    Helmey, Sherif Samir; Rice, Ambrose Eugene; Hatch, Duane Michael; Silks, Louis A.; Marti-Arbona, Ricardo

    2016-08-17

    Unnatural heavy metal-containing amino acid analogs have shown to be very important in the analysis of protein structure, using methods such as X-ray crystallography, mass spectroscopy, and NMR spectroscopy. Synthesis and incorporation of selenium-containing methionine analogs has already been shown in the literature however with some drawbacks due to toxicity to host organisms. Thus synthesis of heavy metal tryptophan analogs should prove to be more effective since the amino acid tryptophan is naturally less abundant in many proteins. For example, bioincorporation of β-seleno[3,2-b]pyrrolyl-L-alanine ([4,5]SeTrp) and β-selenolo[2,3-b]pyrrolyl-L-alanine ([6,7]SeTrp) has been shown in the following proteins without structural or catalytic perturbations: human annexin V, barstar, and dihydrofolate reductase. The reported synthesis of these Se-containing analogs is currently not efficient for commercial purposes. Thus a more efficient, concise, high-yield synthesis of selenotryptophan, as well as the corresponding, tellurotryptophan, will be necessary for wide spread use of these unnatural amino acid analogs. This research will highlight our progress towards a synthetic route of both [6,7]SeTrp and [6,7]TeTrp, which ultimately will be used to study the effect on the catalytic activity of Lignin Peroxidase (LiP).

  15. [Mechanism of metabolic and ionic germination of "Bacillus licheniformis" spores treated with hydrogen peroxide (author's transl)].

    PubMed

    Cerf, O

    1977-01-01

    Spores of Bacillus licheniformis 109-2A0 lost their refractility and absorbancy at 640 nm in the presence of metabolizable molecules (L-alanine). The same occurred with spores treated with 4.4 mol/1 hydrogen peroxide, pH 2.0, at 65 degrees C, even after 5 min of treatment. In addition, these transformations could be promoted after 2 min of treatment by inorganic ions (KI). This possibility occurs following a kinetics of activation. Thermodynamic parameters showed this activation to be combined with a molecular re-organization. Loss of refractility or absorbancy, induced by L-ala or KI, was inhibited by inhibitors of membrane functions or of L-alanine dehydrogenase, enzyme of which a noticeable activity was demonstrated in treated spores. Only 10% of spore calcium leaked during the treatment. Therefore loss of refractility or absorbancy caused by molecules metabolizable or not seemed to correspond to a physiological germination. The first even of the metabolic, as well as or the ionic germination could well be a modification of the spore membrane proton-motive force.

  16. A 1-year study of the activities of seven hydrolases in a communal wastewater treatment plant: trends and correlations.

    PubMed

    Kreutz, Jennifer Anna; Böckenhüser, Ina; Wacht, Marion; Fischer, Klaus

    2016-08-01

    The activities of seven hydrolytic enzymes (L-alanine aminopeptidase, esterase, α-and β-glucosidase, phosphomonoesterase, phosphodiesterase, sulfatase) were monitored during 1 year in parallel and serial treatment units of the biological stage of a communal wastewater treatment plant. The spatial homogeneity of enzyme activities was high (coefficients of variation <10 % for the entire treatment stage). A significant difference between aerated and stirred tanks was not observed. Temperature seemed not to exert a direct influence. Long periods with comparably constant activities were interrupted by a few strong, short-time rises. The mean enzyme activities followed the sequence sulfatase < α-glucosidase < phosphodiesterase ≈ β-glucosidase≈esterase < phosphomonoesterase < L-alanine aminopeptidase. The enzyme activities correlated among themselves at different levels. Very strong (r > 0.8) and highly significant (p < 0.01) correlations between the activities of both glucosidases, both phosphoesterases, and between phosphomonoesterase and both glucosidases were ascertained, pointing to the importance of substrate specificity and similarity of metabolic functions. Moderate and strong activity correlations with various wastewater constituents and with process parameters, e.g., concentrations, loads and eliminated amounts of phosphorous, TOC concentrations and loads of the plant effluent, dry matter content of activated sludge, and sludge volume, were found. The esterase activity was least correlated with other enzymes and often showed deviating dependencies on process parameters, raising questions concerning its appropriateness as a sum parameter for enzymatic and heterotrophic activity.

  17. D-Galacturonic Acid: A Highly Reactive Compound in Nonenzymatic Browning. 2. Formation of Amino-Specific Degradation Products.

    PubMed

    Wegener, Steffen; Bornik, Maria-Anna; Kroh, Lothar W

    2015-07-22

    Thermal treatment of aqueous solutions of D-galacturonic acid and L-alanine at pH 3, 5, and 8 led to rapid and more intensive nonenzymatic browning reactions compared to similar solutions of other uronic acids and to Maillard reactions of reducing sugars. The hemiacetal ring structures of uronic acids had a high impact on browning behavior and reaction pathways. Besides reductic acid (1,2-dihydroxy-2-cyclopenten-1-one), 4,5-dihydroxy-2-cyclopenten-1-one (DHCP), furan-2-carboxaldehyde, and norfuraneol (4-hydroxy-5-methyl-3-(2H)-furanone) could be detected as typical products of nonenzymatic uronic acid browning reactions. 2-(2-Formyl-1H-pyrrole-1-yl)propanoic acid (FPA) and 1-(1-carboxyethyl)-3-hydroxypyridin-1-ium (HPA) were identified as specific reaction products of uronic acids with amine participation like l-alanine. In contrast, the structurally related D-galacturonic acid methyl ester showed less browning activity and degradation under equal reaction conditions. Pectin-specific degradation products such as 5-formyl-2-furanoic acid and 2-furanoic acid were found but could not be verified for d-galacturonic acid monomers alone.

  18. X-ray diffraction study of nanocrystalline and amorphous structure within major and minor ampullate dragline spider silks

    SciTech Connect

    Sampath, Sujatha; Isdebski, Thomas; Jenkins, Janelle E.; Ayon, Joel V.; Henning, Robert W.; Orgel, Joseph P.R.O.; Antipoa, Olga; Yarger, Jeffery L.

    2012-07-25

    Synchrotron X-ray micro-diffraction experiments were carried out on Nephila clavipes (NC) and Argiope aurantia (AA) major (MA) and minor ampullate (MiA) fibers that make up dragline spider silk. The diffraction patterns show a semi-crystalline structure with {beta}-poly(L-alanine) nanocrystallites embedded in a partially oriented amorphous matrix. A superlattice reflection 'S' diffraction ring is observed, which corresponds to a crystalline component larger in size and is poorly oriented, when compared to the {beta}-poly(L-alanine) nanocrystallites that are commonly observed in dragline spider silks. Crystallite size, crystallinity and orientation about the fiber axis have been determined from the wide-angle X-ray diffraction (WAXD) patterns. In both NC and AA, the MiA silks are found to be more highly crystalline, when compared with the corresponding MA silks. Detailed analysis on the amorphous matrix shows considerable differences in the degree of order of the oriented amorphous component between the different silks studied and may play a crucial role in determining the mechanical properties of the silks.

  19. Accessory cell function of liver granuloma macrophages of Schistosoma mansoni-infected mice.

    PubMed Central

    Schook, L B; Wellhausen, S R; Boros, D L; Niederhuber, J E

    1983-01-01

    In murine schistosomiasis mansoni, the inflammatory macrophage comprises 30% of the granuloma which forms around parasite eggs in the tissue. These granuloma macrophages (GR-Mphi) displayed dense Fc and C3 receptors, and about 50% expressed H-2I region-encoded determinants (Ia antigens). These GR-Mphi were able to effectively reconstitute the burro erythrocyte-specific immunoglobulin M and G antibody response of primed macrophage-depleted spleen cells. However, in contrast to splenic macrophages, GR-Mphi gave only minimal reconstitution of the primary immunoglobulin M response. The reconstitution of the T-cell proliferative response to L-glutamic60-L-alanine30-L-tyrosine10, an antigen under Ir gene control, was also observed when GR-Mphi were added to purified lymph node T-cells. The addition of a monoclonal antibody recognizing a determinant on the Ia complex effectively blocked L-glutamic60-L-alanine30-L-tyrosine10 presentation by GR-Mphi. These studies demonstrated that inflammatory GR-Mphi could function as antigen-presenting cells and that this accessory function was mediated by H-2I region gene products. PMID:6605931

  20. Chiral resolution of salbutamol in plasma sample by a new chiral ligand-exchange chromatography method after its extraction with nano-sized imprinted polymer.

    PubMed

    Alizadeh, Taher; Shamkhali, Amir Naser

    2016-01-15

    A new chromatographic procedure, based upon chiral ligand-exchange principal, was developed for the resolution of salbutamol enantiomers. The separation was carried out on a C18 column. (l)-Alanine and Cu(2+) were applied as chiral resolving agent and complexing ion, respectively. The kind of copper salt had definitive effect on the enantioseparation. Density functional theory (DFT) was used to substantiate the effect of various anions, accompanying Cu(2+), on the formation of ternary complexes, assumed to be created during separation process. The DFT results showed that the anion kind had huge effect on the stability difference between two corresponding diastereomeric complexes and their chemical structures. It was shown that the extent of participation of the chiral selector in the ternary diastereomeric complexes formation was managed by the anion kind, affecting thus the enantioseparation efficiency of the developed method. Water/methanol (70:30) mixture containing (l)-alanine-Cu(2+) (4:1) was found to be the best mobile phase for salbutamol enantioseparation. In order to analyze sulbutamol enantiomers in plasma samples, racemic salbutamol was first extracted from the samples via nano-sized salbutamol-imprinted polymer and then enantioseparated by the developed method.

  1. Synthesis of deuterium-labelled halogen derivatives of L-tryptophan catalysed by tryptophanase.

    PubMed

    Winnicka, Elżbieta; Szymańska, Jolanta; Kańska, Marianna

    2016-06-01

    The isotopomers of halogen derivatives of l-tryptophan (l-Trp) (4'-F-, 7'-F-, 5'-Cl- and 7'-Br-l-Trp), specifically labelled with deuterium in α-position of the side chain, were obtained by enzymatic coupling of the corresponding halogenated derivatives of indole with S-methyl-l-cysteine in (2)H2O, catalysed by enzyme tryptophanase (EC 4.1.99.1). The positional deuterium enrichment of the resulting tryptophan derivatives was controlled using (1)H NMR. In accordance with the mechanism of the lyase reaction, a 100% deuterium labelling was observed in the α-position; the chemical yields were between 23 and 51%. Furthermore, β-F-l-alanine, synthesized from β-F-pyruvic acid by the l-alanine dehydrogenase reaction, has been tested as a coupling agent to obtain the halogenated deuterium-labelled derivatives of l-Trp. The chemical yield (∼30%) corresponded to that as observed with S-methyl-l-cysteine but the deuterium label was only 63%, probably due to the use of a not completely deuterated incubation medium.

  2. Influence of l-pyroglutamic acid on the color formation process of non-enzymatic browning reactions.

    PubMed

    Wegener, Steffen; Kaufmann, Martin; Kroh, Lothar W

    2017-10-01

    Heating aqueous d-glucose model reactions with l-glutamine and l-alanine yielded similar colored solutions. However, size-exclusion chromatography (SEC) revealed that both non-enzymatic browning reactions proceeded differently. Due to a fast occurring cyclization of l-glutamine to pyroglutamic acid, the typical amino-carbonyl reaction was slowed down. However, l-glutamine and l-alanine model reactions showed the same browning index. Closer investigations could prove that l-pyroglutamic acid was able to influence non-enzymatic browning reactions. SEC analyses of d-glucose model reactions with and without l-pyroglutamic acid revealed an increase of low molecular colored compounds in the presence of l-pyroglutamic acid. Polarimetric measurements showed a doubling of d-glucose mutarotation velocity and HPLC analyses of d-fructose formation during thermal treatment indicated a tripling of aldose-ketose transformation in the presence of l-pyroglutamic acid, which are signs of a faster proceeding non-enzymatic browning process. 2-Pyrrolidone showed no such behavior, thus the additional carboxylic group should be responsible for the observed effects. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Analysis of the germination proteins in Alicyclobacillus acidoterrestris spores subjected to external factors.

    PubMed

    Porębska, Izabela; Sokołowska, Barbara

    2017-01-01

    The presence of Alicyclobacillus acidoterrestris, a thermoacidophilic and spore-forming bacterium, in pasteurized acidic juices poses a serious problem for the processing industry. Therefore, the use of other more effective techniques, such as high hydrostatic pressure (HHP) and supercritical carbon dioxide (SCCD), is considered for preserving juices in order to inactivate these bacteria, while reducing the loss of nutrients and sensory quality of juices. On the other hand, HHP and SCCD when combined with a moderately elevated temperature can induce germination of bacterial spores, making them more vulnerable to inactivation. The spore germination can be also induced by nutrients, such as L-alanine or a mixture of asparagine, glucose, fructose and potassium ions (AGFK). The aim of this work was to determine whether applying activating agents: HHP, SCCD and nutrient germinants (L-alanine and the AGFK mixture), could influence the number of spores which start to germinate and how this affects the proteins involved in the spore germination. SDS-PAGE was used to resolve proteins isolated from the A. acidoterrestris spores. The results that were obtained indicate that the germination of A. acidoterrestris spores treated with HHP, SCCD and nutrient germinants reflect the number of spores which start to germinate. The SDS-PAGE data indicated changes in the level of selected proteins occurring when subjected to the germination activating factors as well as noticeable differences in those proteins' molecular weights.

  4. Reducing lactate secretion by ldhA Deletion in L-glutamate- producing strain Corynebacterium glutamicum GDK-9

    PubMed Central

    Zhang, Dalong; Guan, Dan; Liang, Jingbo; Guo, Chunqian; Xie, Xixian; Zhang, Chenglin; Xu, Qingyang; Chen, Ning

    2014-01-01

    L-lactate is one of main byproducts excreted in to the fermentation medium. To improve L-glutamate production and reduce L-lactate accumulation, L-lactate dehydrogenase-encoding gene ldhA was knocked out from L-glutamate producing strain Corynebacterium glutamicum GDK-9, designated GDK-9ΔldhA. GDK-9ΔldhA produced approximately 10.1% more L-glutamate than the GDK-9, and yielded lower levels of such by-products as α-ketoglutarate, L-lactate and L-alanine. Since dissolved oxygen (DO) is one of main factors affecting L-lactate formation during L-glutamate fermentation, we investigated the effect of ldhA deletion from GDK-9 under different DO conditions. Under both oxygen-deficient and high oxygen conditions, L-glutamate production by GDK-9ΔldhA was not higher than that of the GDK-9. However, under micro-aerobic conditions, GDK-9ΔldhA exhibited 11.61% higher L-glutamate and 58.50% lower L-alanine production than GDK-9. Taken together, it is demonstrated that deletion of ldhA can enhance L-glutamate production and lower the unwanted by-products concentration, especially under micro-aerobic conditions. PMID:25763057

  5. Bacteriocin (Hemolysin) of Streptococcus zymogenes

    PubMed Central

    Basinger, Scott F.; Jackson, Robert W.

    1968-01-01

    The sensitivity of Streptococcus faecalis (ATTC 8043) to S. zymogenes X-14 bacteriocin depends greatly on its physiological age. Sensitivity decreases from the mid-log phase on and is completely lost in the stationary phase. The sensitivity of erythrocytes to the hemolytic capacity of the bacteriocin showed considerable species variation. The order of increasing sensitivity was goose < sheep < dog < horse < human < rabbit. However, when red cell stromata were used as inhibitors of hemolysis in a standard system employing rabbit erythrocytes the order of increasing effectiveness was sheep < rabbit < human < horse < goose. When rabbit cells were used in varying concentrations with a constant hemolysin concentration, there was a lag of about 30 min, which for a given hemolysin preparation was constant for all red cell concentrations. Furthermore, the rate of hemolysis increased with increasing red cell concentration. If red cells are held constant and lysin varied, the time to reach half-maximal lysis varies directly with lysin but is not strictly proportional. Bacterial membranes were one to three orders of magnitude more effective than red cell stromata as inhibitors. The order of increasing effectiveness seems to be Escherichia coli < Bacillus megaterium < S. faecalis < Micrococcus lysodeikticus. In addition to membranes, a d-alanine containing glycerol teichoic acid, trypsin in high concentration, and deoxyribonuclease also inhibited hemolysis. Ribonuclease, d-alanine, l-alanine, dl-alanyl-dl-alanine, N-acetyl-d-alanine, N-acetyl-l-alanine did not inhibit hemolysis. PMID:4972910

  6. Detection of Cyanotoxins in Algae Dietary Supplements.

    PubMed

    Roy-Lachapelle, Audrey; Solliec, Morgan; Bouchard, Maryse F; Sauvé, Sébastien

    2017-02-25

    Algae dietary supplements are marketed worldwide as natural health products. Although their proprieties have been claimed as beneficial to improve overall health, there have been several previous reports of contamination by cyanotoxins. These products generally contain non-toxic cyanobacteria, but the methods of cultivation in natural waters without appropriate quality controls allow contamination by toxin producer species present in the natural environment. In this study, we investigated the presence of total microcystins, seven individual microcystins (RR, YR, LR, LA, LY, LW, LF), anatoxin-a, dihydroanatoxin-a, epoxyanatoxin-a, cylindrospermopsin, saxitoxin, and β-methylamino-l-alanine in 18 different commercially available products containing Spirulina or Aphanizomenon flos-aquae. Total microcystins analysis was accomplished using a Lemieux oxidation and a chemical derivatization using dansyl chloride was needed for the simultaneous analysis of cylindrospermopsin, saxitoxin, and β-methylamino-l-alanine. Moreover, the use of laser diode thermal desorption (LDTD) and ultra-high performance liquid chromatography (UHPLC) both coupled to high resolution mass spectrometry (HRMS) enabled high performance detection and quantitation. Out of the 18 products analyzed, 8 contained some cyanotoxins at levels exceeding the tolerable daily intake values. The presence of cyanotoxins in these algal dietary supplements reinforces the need for a better quality control as well as consumer's awareness on the potential risks associated with the consumption of these supplements.

  7. Cyanogenesis - a general phenomenon in the lepidoptera

    SciTech Connect

    Witthohn, K.; Naumann, C.M.

    1987-08-01

    There are two different pathways known to be used for the detoxification of hydrocyanic acid in insects, viz., rhodanese and ..beta..-cyano-L-alanine synthase. The authors consider the latter to be indicative for cyanogenesis, while rhodanese might, in general, play a more important role in sulfur transfer for protein synthesis. This paper reports on the distribution of ..beta..-cyano-L-alanine (BCA) in the Lepidoptera. First reports of cyanogenesis are presented for the following families: Papilionidae, Pieridae, Lycaenidae, Hesperiidae, Lymantriidae, Arctiidae, Notodontidae, Megalopygidae, Limacodidae, Cymatophoridae, Noctuidae, Geometridae, and Yponomeutidae. New and old records for three other families, the Nymphalidae, Zygaenidae, and Heterogynidae, are included to complete the present state of knowledge. Special emphasis has been laid on the Nymphalidae, where BCA has been detected in eight subfamilies. Taxonomic, geographic, and seasonal variation has been found in a number of cases. In all cases observed so far, the source of cyanogenesis in the Lepidoptera is most probably the cyanoglucosides linamarin and lotaustralin, although cyanogenesis based on mustard oil glucosides and cyclopentenoid glucosides might occur as well. BCA has been found in both cryptic and aposematic species, including taxa such as the Pieridae, Danainae, Ithomiinae, and Arctiidae, where the defensive biology is believed to be linked with other compounds, like mustard oil glucosides, cardenolides, or pyrrolizidinie alkaloids. The ecological interaction and significance of such secondary compounds is not yet understood.

  8. Cysteine sulfinate desulfinase, a NIFS-like protein of Escherichia coli with selenocysteine lyase and cysteine desulfurase activities. Gene cloning, purification, and characterization of a novel pyridoxal enzyme.

    PubMed

    Mihara, H; Kurihara, T; Yoshimura, T; Soda, K; Esaki, N

    1997-09-05

    Selenocysteine lyase (EC 4.4.1.16) exclusively decomposes selenocysteine to alanine and elemental selenium, whereas cysteine desulfurase (NIFS protein) of Azotobacter vinelandii acts indiscriminately on both cysteine and selenocysteine to produce elemental sulfur and selenium respectively, and alanine. These proteins exhibit some sequence homology. The Escherichia coli genome contains three genes with sequence homology to nifS. We have cloned the gene mapped at 63.4 min in the chromosome and have expressed, purified to homogeneity, and characterized the gene product. The enzyme comprises two identical subunits with 401 amino acid residues (Mr 43,238) and contains pyridoxal 5'-phosphate as a coenzyme. The enzyme catalyzes the removal of elemental sulfur and selenium atoms from L-cysteine, L-cystine, L-selenocysteine, and L-selenocystine to produce L-alanine. Because L-cysteine sulfinic acid was desulfinated to form L-alanine as the preferred substrate, we have named this new enzyme cysteine sulfinate desulfinase. Mutant enzymes having alanine substituted for each of the four cysteinyl residues (Cys-100, Cys-176, Cys-323, and Cys-358) were all active. Cys-358 corresponds to Cys-325 of A. vinelandii NIFS, which is conserved among all NIFS-like proteins and catalytically essential (Zheng, L., White, R. H., Cash, V. L., and Dean, D. R. (1994) Biochemistry 33, 4714-4720), is not required for cysteine sulfinate desulfinase. Thus, the enzyme is distinct from A. vinelandii NIFS in this respect.

  9. Substrate Availability of Mutant SPT Alters Neuronal Branching and Growth Cone Dynamics in Dorsal Root Ganglia

    PubMed Central

    Jun, Byung Kyu; Chandra, Ankush; Kuljis, Dika; Schmidt, Brian P.

    2015-01-01

    Serine palmitoyltransferase (SPT) is a key enzyme in the first step of sphingolipid biosynthesis. Mutations in the SPTLC1 gene that encodes for SPT subunits cause hereditary sensory neuropathy type 1. However, little is understood about how mutant SPT regulates mechanisms of sensory neuron and axonal growth. Using transgenic mice overexpressing the C133W SPT mutant, we found that mutant dorsal root ganglia (DRG) during growth in vitro exhibit increased neurite length and branching, coinciding with elevated expression of actin-cross-linking proteins at the neuronal growth cone, namely phosphorylated Ezrin/Radixin/Moesin. In addition, inhibition of SPT was able to reverse the mutant phenotype. Because mutant SPT preferentially uses l-alanine over its canonical substrate l-serine, we also investigated the effects of substrate availability on DRG neurons. Supplementation with l-serine or removal of l-alanine independently restored normal growth patterns in mutant SPTLC1C133W DRG. Therefore, we report that substrate availability and selectivity of SPT influence the regulation of neurite growth in DRG neurons. SIGNIFICANCE STATEMENT Hereditary sensory neuropathy type 1 is an autosomal-dominant disorder that leads to a sensory neuropathy due to mutations in the serine palmitoyltransferase (SPT) enzyme. We investigated how mutant SPT and substrate levels regulate neurite growth. Because SPT is an important enzyme in the synthesis of sphingolipids, our data are of broader significance to other peripheral and metabolic disorders. PMID:26446223

  10. D-amino acid-induced expression of D-amino acid oxidase in the yeast Schizosaccharomyces pombe.

    PubMed

    Takahashi, Shouji; Okada, Hirotsune; Abe, Katsumasa; Kera, Yoshio

    2012-12-01

    We investigated D-amino acid oxidase (DAO) induction in the popular model yeast Schizosaccharomyces pombe. The product of the putative DAO gene of the yeast expressed in E. coli displayed oxidase activity to neutral and basic D-amino acids, but not to an L-amino acid or acidic D-amino acids, showing that the putative DAO gene encodes catalytically active DAO. DAO activity was weakly detected in yeast cells grown on a culture medium without D-amino acid, and was approximately doubled by adding D-alanine. The elimination of ammonium chloride from culture medium induced activity by up to eight-fold. L-Alanine also induced the activity, but only by about half of that induced by D-alanine. The induction by D-alanine reached a maximum level at 2 h cultivation; it remained roughly constant until cell growth reached a stationary phase. The best inducer was D-alanine, followed by D-proline and then D-serine. Not effective were N-carbamoyl-D,L-alanine (a better inducer of DAO than D-alanine in the yeast Trigonopsis variabilis), and both basic and acidic D-amino acids. These results showed that S. pombe DAO could be a suitable model for analyzing the regulation of DAO expression in eukaryotic organisms.

  11. Quantification of amino acids in fermentation media by isocratic HPLC analysis of their α-hydroxy acid derivatives.

    PubMed

    Pleissner, Daniel; Wimmer, Reinhard; Eriksen, Niels T

    2011-01-01

    In this paper we describe a novel method for quantification of amino acids. First, α-hydroxy acid derivatives of amino acids were formed after reaction with dinitrogen trioxide by the van Slyke reaction. Second, the α-hydroxy acid derivatives were separated on an Aminex HPX-87H column (Bio-Rad) eluted isocratically with 5 mM H(2)SO(4) and quantified by refractive index detection. We were able to measure the reaction products of 13 of the 20 classical amino acids: glycine, l-alanine, l-valine, l-leucine, l-isoleucine, l-methionine, l-serine, l-threonine, l-asparagine, l-glutamine, l-aspartic acid, l-glutamic acid, and l-proline. We obtained linear relationships between the product peak areas and initial amino acid concentration, whereby the concentrations of these amino acids could be quantified on the basis of the quantification of their products. The method can be used to analyze amino acids in parallel with other small molecules, such as sugars or short chain fatty acids, and was used for parallel quantification of glycine, l-alanine, or l-glutamic acid, and glucose uptake in cultures of the heterotrophic dinoflagellate Crypthecodinium cohnii . The method can also be used to quantify other amines, as demonstrated by detection of Tris (2-amino-2-(hydroxymethyl)propane-1,3-diol).

  12. Synthesis of nano-sized stereoselective imprinted polymer by copolymerization of (S)-2-(acrylamido) propanoic acid and ethylene glycol dimethacrylate in the presence of racemic propranolol and copper ion.

    PubMed

    Alizadeh, Taher; Bagherzadeh, Azam; Shamkhali, Amir Nasser

    2016-06-01

    A new chiral functional monomer of (S)-2-(acrylamido) propanoic acid was obtained by reaction of (l)-alanine with acryloyl chloride. The resulting monomer was characterized by FT-IR and HNMR and then utilized for the preparation of chiral imprinted polymer (CIP). This was carried out by copolymerization of (l)-alanine-derived chiral monomer and ethylene glycol dimethacrylate, in the presence of racemic propranolol and copper nitrate, via precipitation polymerization technique, resulting in nano-sized networked polymer particles. The polymer obtained was characterized by scanning electron microscopy and FT-IR. The non-imprinted polymer was also synthesized and used as blank polymer. Density functional theory (DFT) was also employed to optimize the structures of two diasterometric ternary complexes, suspected to be created in the pre-polymerization step, by reaction of optically active isomers of propranolol, copper ion and (S)-2-(acrylamido) propanoic acid. Relative energies and other characteristics of the described complexes, calculated by the DFT, predicted the higher stability of (S)-propranolol involved complex, compared to (R)-propranolol participated complex. Practical batch extraction test which employed CIP as solid phase adsorbent, indicated that the CIP recognized selectively (S)-propranolol in the racemic mixture of propranolol; whereas, the non-imprinted polymer (NIP) showed no differentiation capability between two optically active isomers of propranolol.

  13. Structural evolution of amino acid crystals under stress from a non-empirical density functional

    NASA Astrophysics Data System (ADS)

    Sabatini, Riccardo; Küçükbenli, Emine; Kolb, Brian; Thonhauser, T.; de Gironcoli, Stefano

    2012-10-01

    Use of the non-local correlation functional vdW-DF (from ‘van der Waals density functional’ Dion M et al 2004 Phys. Rev. Lett. 92 246401) has become a popular approach for including van der Waals interactions within density functional theory. In this work, we extend the vdW-DF theory and derive the corresponding stress tensor in a fashion similar to the LDA and GGA approach, which allows for a straightforward implementation in any electronic structure code. We then apply our methodology to investigate the structural evolution of amino acid crystals of glycine and l-alanine under pressure up to 10 GPa—with and without van der Waals interactions—and find that for an accurate description of intermolecular interactions and phase transitions in these systems, the inclusion of van der Waals interactions is crucial. For glycine, calculations including the vdW-DF (vdW-DF-c09x) functional are found to systematically overestimate (underestimate) the crystal lattice parameters, yet the stability ordering of the different polymorphs is determined accurately, at variance with the GGA case. In the case of l-alanine, our vdW-DF results agree with recent experiments that question the phase transition reported for this crystal at 2.3 GPa, as the a and c cell parameters happen to become equal but no phase transition is observed.

  14. Structure of supersaturated solution and crystal nucleation induced by diffusion

    NASA Astrophysics Data System (ADS)

    Ooshima, Hiroshi; Igarashi, Koichi; Iwasa, Hideo; Yamamoto, Ren

    2013-06-01

    The effect of a seed crystal on nucleation of L-alanine from a quiescent supersaturated solution was investigated. When a seed crystal was not used, nucleation did not occur at least for 5 h. When a seed crystal was introduced into the supersaturated solution with careful attention to avoid convection of the solution, fine crystals appeared at the place far from the seed crystal. At that time, there was no convection at the place that fine crystals appeared. Namely, there was no possibility that those fine crystals came from the surface of seed crystal. We supposed that nucleation was induced by directional diffusion of solute molecules caused by growth of the seed crystal. In order to prove this hypothesis, we designed an experiment using an apparatus composed of two compartments divided by a dialysis membrane that L-alanine molecules could freely permeate. Two supersaturated solutions having a supersaturation ratio of 1.2 and a smaller ratio were placed in the two compartments in the absence of seed crystals. This apparatus allowed the directional diffusion of solute molecules between two solutions. Nucleation occurred within 30 min. The frequency of nucleation among 7-times repeated experiments was in proportion to the difference of supersaturation ratio between the two solutions. This result poses a new mechanism of the secondary nucleation that the directional diffusion caused by growth of existing crystals induces nucleation.

  15. Temperature effects in first-principles solid state calculations of the chemical shielding tensor made simple

    NASA Astrophysics Data System (ADS)

    Monserrat, Bartomeu; Needs, Richard J.; Pickard, Chris J.

    2014-10-01

    We study the effects of atomic vibrations on the solid-state chemical shielding tensor using first principles density functional theory calculations. At the harmonic level, we use a Monte Carlo method and a perturbative expansion. The Monte Carlo method is accurate but computationally expensive, while the perturbative method is computationally more efficient, but approximate. We find excellent agreement between the two methods for both the isotropic shift and the shielding anisotropy. The effects of zero-point quantum mechanical nuclear motion are important up to relatively high temperatures: at 500 K they still represent about half of the overall vibrational contribution. We also investigate the effects of anharmonic vibrations, finding that their contribution to the zero-point correction to the chemical shielding tensor is small. We exemplify these ideas using magnesium oxide and the molecular crystals L-alanine and β-aspartyl-L-alanine. We therefore propose as the method of choice to incorporate the effects of temperature in solid state chemical shielding tensor calculations using the perturbative expansion within the harmonic approximation. This approach is accurate and requires a computational effort that is about an order of magnitude smaller than that of dynamical or Monte Carlo approaches, so these effects might be routinely accounted for.

  16. Solvation and hydrogen bonding in alanine- and glycine-containing dipeptides probed using solution- and solid-state NMR spectroscopy.

    PubMed

    Bhate, Manasi P; Woodard, Jaie C; Mehta, Manish A

    2009-07-15

    The NMR chemical shift is a sensitive reporter of peptide secondary structure and its solvation environment, and it is potentially rich with information about both backbone dihedral angles and hydrogen bonding. We report results from solution- and solid-state (13)C and (15)N NMR studies of four zwitterionic model dipeptides, L-alanyl-L-alanine, L-alanyl-glycine, glycyl-L-alanine, and glycyl-glycine, in which we attempt to isolate structural and environmental contributions to the chemical shift. We have mapped hydrogen-bonding patterns in the crystalline states of these dipeptides using the published crystal structures and correlated them with (13)C and (15)N magic angle spinning chemical shift data. To aid in the interpretation of the solvated chemical shifts, we performed ab initio quantum chemical calculations to determine the low-energy conformers and their chemical shifts. Assuming low energy barriers to interconversion between thermally accessible conformers, we compare the Boltzmann-averaged chemical shifts with the experimentally determined solvated-state shifts. The results allow us to correlate the observed differences in chemical shifts between the crystalline and solvated states to changes in conformation and hydrogen bonding that occur upon solvation.

  17. Gene cloning of alpha-methylserine aldolase from Variovorax paradoxus and purification and characterization of the recombinant enzyme.

    PubMed

    Nozaki, Hiroyuki; Kuroda, Shinji; Watanabe, Kunihiko; Yokozeki, Kenzo

    2008-10-01

    The alpha-methylserine aldolase gene from Variovorax paradoxus strains AJ110406, NBRC15149, and NBRC15150 was cloned and expressed in Escherichia coli. Formaldehyde release activity from alpha-methyl-L-serine was detected in the cell-free extract of E.coli expressing the gene from three strains. The recombinant enzyme from V. paradoxus NBRC15150 was purified. The Vmax and Km of the enzyme for the formaldehyde release reaction from alpha-methyl-L-serine were 1.89 micromol min(-1) mg(-1) and 1.2 mM respectively. The enzyme was also capable of catalyzing the synthesis of alpha-methyl-L-serine and alpha-ethyl-L-serine from L-alanine and L-2-aminobutyric acid respectively, accompanied by hydroxymethyl transfer from formaldehyde. The purified enzyme also catalyzed alanine racemization. It contained 1 mole of pyridoxal 5'-phosphate per mol of the enzyme subunit, and exhibited a specific spectral peak at 429 nm. With L-alanine and L-2-aminobutyric acid as substrates, the specific peak, assumed to be a result of the formation of a quinonoid intermediate, increased at 498 nm and 500 nm respectively.

  18. METABOLIC CHARACTERIZATION OF THE GENUS BRUCELLA I.

    PubMed Central

    Meyer, Margaret E.; Cameron, H. S.

    1961-01-01

    Meyer, Margaret E. (University of California, Davis), and H. S. Cameron. Metabolic characterization of the genus Brucella. I. Statistical evaluation of the oxidative rates by which type I of each species can be identified. J. Bacteriol. 82:387–395. 1961.—The oxidative uptake rates on 11 amino acid and seven carbohydrate substrates were determined for 75 strains of brucellae that had been identified by the conventional determinative methods as Brucella melitensis type I, Brucella abortus type I, or Brucella suis type I. By calculating the standard deviation of the oxidative rates, it was demonstrated that a metabolic pattern that is characteristic and definitive for each of the species was formed by their differential oxidative utilization of substrate groups, and that qualitative as well as quantitative metabolic differences exist among the Brucella species. B. melitensis oxidized l-alanine, l-asparagine, and l-glutamic acid, but not l-arginine, dl-citrulline, l-lysine, dl-ornithine, l-arabinose, d-galactose, d-ribose, or d-xylose. B. abortus differed qualitatively from B. melitensis in that it oxidized the carbohydrate substrates. B. suis differed quantitatively from both of these species in its consistently low oxidative rates of l-alanine, l-asparagine, and l-glutamic acid, and its high rates of utilization of the carbohydrate substrates. It differed qualitatively in that it oxidized the four amino acid substrates that are components of the urea cycle. PMID:13770011

  19. Synthesis of thiourea-tethered C-glycosyl amino acids via isothiocyanate-amine coupling.

    PubMed

    Barghash, Reham F; Massi, Alessandro; Dondoni, Alessandro

    2009-08-21

    A new class of C-glycosyl amino acids displaying a thiourea segment as a linker has been designed and synthesized by addition of peracetylated glycosylmethyl isothiocyanates to an amine-functionalized amino acid (N(alpha)-Fmoc-beta-amino-l-alanine). Three pairs of compounds with alpha- and beta-galacto, alpha- and beta-gluco, and alpha- and beta-manno configuration have been prepared with yields ranging between 70 and 75%. The orthogonal set of protective groups (O-acetyl in the carbohydrate moiety and N-Fmoc in the amino acid residue) makes these compounds suitable substrates for the co-translational modification of natural peptides. The couplings of model hydroxy-free and perbenzylated glycosylmethyl isothiocyanates with the above N(alpha)-Fmoc-beta-amino-l-alanine and the N(alpha)-Boc-protected analogue have been carried out as well, thus broadening the scope of the coupling reaction. Nevertheless, there are limitations of this isothiocyanate-amine coupling in complex systems, and these are briefly discussed.

  20. Use of Rasch analysis to refine a patient-reported questionnaire on satisfaction with communication of the multiple sclerosis diagnosis.

    PubMed

    Solari, A; Grzeda, M; Giordano, A; Mattarozzi, K; D'Alessandro, R; Simone, A; Tesio, L

    2014-08-01

    The Comunicazione medico-paziente nella Sclerosi Multipla - Revised (COSM-R) is a patient self-assessed questionnaire probing the moment of multiple sclerosis (MS) diagnosis disclosure (section 1, five items) and following period (section 2, 15 items). This study examined COSM-R dimensionality and measurement properties through Rasch analysis (partial-credit model) and proposed a revised questionnaire. Cross-sectional COSM-R data were obtained from 1068 people with MS (PwMS, 1065 questionnaires) participating in four studies (102 centres). Mean age was 40 years (range 17-73); 70% were women; 53% were from Northern, 25% from Central, and 21% from Southern Italy. Unidimensionality was not confirmed for COSM-R section 1, but was for section 2 after removal of three items. The revised instrument (COSM-S, Shortened) consisted of the original five-item checklist (section 1), modified by removing the table grouping of three items, and 12 of the original 15 section 2 items, which could now be summed and transformed into an interval scale. Scores were higher for items assessing emotional satisfaction than for those assessing informational satisfaction. The proposed COSM-S is a composite measure of satisfaction with MS diagnosis communication with improved metric properties over the original COSM-R, and whose section 2 satisfies Rasch model expectations. © The Author(s) 2014.

  1. Development and validation of a patient self-assessed questionnaire on satisfaction with communication of the multiple sclerosis diagnosis.

    PubMed

    Solari, A; Mattarozzi, K; Vignatelli, L; Giordano, A; Russo, P M; Uccelli, M Messmer; D'Alessandro, R

    2010-10-01

    We describe the development and clinical validation of a patient self-administered tool assessing the quality of multiple sclerosis diagnosis disclosure. A multiple sclerosis expert panel generated questionnaire items from the Doctor's Interpersonal Skills Questionnaire, literature review, and interviews with neurology inpatients. The resulting 19-item Comunicazione medico-paziente nella Sclerosi Multipla (COSM) was pilot tested/debriefed on seven patients with multiple sclerosis and administered to 80 patients newly diagnosed with multiple sclerosis. The resulting revised 20-item version (COSM-R) was debriefed on five patients with multiple sclerosis, field tested/debriefed on multiple sclerosis patients, and field tested on 105 patients newly diagnosed with multiple sclerosis participating in a clinical trial on an information aid. The hypothesized monofactorial structure of COSM-R section 2 was tested on the latter two groups. The questionnaire was well accepted. Scaling assumptions were satisfactory in terms of score distributions, item-total correlations and internal consistency. Factor analysis confirmed section 2's monofactorial structure, which was also test-retest reliable (intraclass correlation coefficient [ICC] 0.73; 95% CI 0.54-0.85). Section 1 had only fair test-retest reliability (ICC 0.45; 95% CI 0.12-0.69), and three items had 8-21% missed responses. COSM-R is a brief, easy-to-interpret MS-specific questionnaire for use as a health care indicator.

  2. Lipid metabolism in pigs fed supplemental conjugated linoleic acid and/or dietary arginine.

    PubMed

    Go, Gwangwoong; Wu, Guoyao; Silvey, David T; Choi, Seongho; Li, Xilong; Smith, Stephen B

    2012-10-01

    We proposed that the combination of conjugated linoleic acid (CLA) and arginine would decrease adiposity by depressing lipid synthesis in liver and adipose tissues of growing pigs. Pigs were allotted to treatments in a 2 × 2 factorial design with two lipids (CLA or canola oil) and two amino acids [L-arginine or L-alanine (isonitrogenous control)]; supplements were provided from 80 to 110 kg body weight (approximately 4 weeks). Treatment groups (n = 4) were: control (2.05% L-alanine plus 1% canola oil); CLA (2.05% L-alanine plus 1% CLA); arginine (1.0% L-arginine plus 1.0% canola oil); arginine plus CLA (1.0% arginine plus 1.0% CLA). Arginine increased backfat thickness (P = 0.07) in the absence or presence of CLA, and arginine supplementation increased subcutaneous and retroperitoneal adipocyte volume, especially in combination with dietary CLA (interaction P = 0.001). Arginine increased palmitate incorporation into total lipids by over 60% in liver (P = 0.07). Dietary CLA increased palmitate incorporation into lipids in longissimus muscle by over 100% (P = 0.01), and CLA increased longissimus muscle lipid by nearly 20%. CLA increased glucose oxidation to CO(2) by over 80% in retroperitoneal and subcutaneous adipose tissues (P = 0.04), and doubled palmitate oxidation to CO(2) in intestinal duodenal mucosal cells (P = 0.07). Arginine supplementation decreased muscle pH at 45 min postmortem (P = 0.001), indicating elevated early postmortem glycolysis, and CLA and arginine independently increased PGC-1α gene expression in longissimus muscle. CLA but not arginine depressed mTOR gene expression in intestinal duodenal mucosal cells. CLA decreased serum insulin by 50% (P = 0.02) but increased serum triacylglycerols by over 40%. CLA supplementation increased (P ≤ 0.01) total saturated fatty acids in liver and adipose tissue. In conclusion, neither CLA nor arginine depressed tissue lipid synthesis in growing/finishing pigs, and in fact dietary CLA promoted elevated

  3. Responses of single facial taste fibers in the sea catfish, Arius felis, to amino acids.

    PubMed

    Michel, W; Caprio, J

    1991-07-01

    1. Taste buds in catfish are found not only within the oropharyngeal cavity, as in mammals, but are also located along the external body surface of the animal from the barbels and lips to the caudal fin. Because these taste buds are innervated by the facial (cranial VII) nerve, the extraoral taste system of catfish is analogous to the mammalian taste system of the anterior two-thirds of the tongue, which contains taste buds innervated by the chorda tympani nerve, and of the soft palate and nasoincisor ducts, which contain taste buds innervated by the greater superficial petrosal nerve. 2. The majority of information concerning the specificity of individual taste fibers in vertebrates has been obtained primarily in mammals to stimuli representing the four basic human taste qualities (i.e., salty, sweet, sour, and bitter). In the present report, we examine the evidence for gustatory fiber types within the stimulus class of amino acids, compounds known to be especially relevant gustatory stimuli for catfish and other teleosts. 3. Action potentials were recorded from 60 individual facial taste neurons obtained from 28 sea catfish (Arius felis). Stimuli were 10(-4) M concentrations of L-alanine, D-alanine, glycine, L-proline, L-histidine, and L-arginine, compounds selected from an original stimulus list of 28 amino acids. Responses were quantified as the number of action potentials evoked at various time intervals from the first 0.5 s up to 10 s of response time. 4. The spontaneous activity of 42 fully characterized neurons was 0.8 +/- 2.1 SD spikes/3 s. The average rate of spike discharge increased 50-fold during stimulation with the most effective amino acid (42 +/- 31 spikes/3 s, mean +/- SD). The majority of the sampled neurons were not narrowly tuned to the amino acid stimulants tested (mean breadth of responsiveness, H = 0.60; range 0-0.95). 5. Hierarchical cluster analysis of the fully characterized neurons identified two large and two small groups of cells. The

  4. The Clostridium botulinum GerAB germination protein is located in the inner membrane of spores.

    PubMed

    Alberto, François; Botella, Lucien; Carlin, Fréderic; Nguyen-The, Christophe; Broussolle, Véronique

    2005-12-15

    Clostridium botulinum dormant spores germinate in presence of l-alanine via a specific receptor composed of GerAA, GerAB and GerAC proteins. In Bacillus subtilis spores, GerAA and GerAC proteins were located in the inner membrane of the spore. We studied the location of the GerAB protein in C. botulinum spore fractions by Western-blot analysis, using an antipeptidic antibody. The protein GerAB was in vitro translated and used to confirm the specificity of the antibodies. GerAB was not present in a coat and spore outer membrane fraction but was present in a fraction of decoated spores containing inner membrane. These results strongly suggest that the protein GerAB is located in the inner membrane of the spore.

  5. Investigation of antibacterial mechanism and identification of bacterial protein targets mediated by antibacterial medicinal plant extracts.

    PubMed

    Yong, Ann-Li; Ooh, Keng-Fei; Ong, Hean-Chooi; Chai, Tsun-Thai; Wong, Fai-Chu

    2015-11-01

    In this paper, we investigated the antibacterial mechanism and potential therapeutic targets of three antibacterial medicinal plants. Upon treatment with the plant extracts, bacterial proteins were extracted and resolved using denaturing gel electrophoresis. Differentially-expressed bacterial proteins were excised from the gels and subjected to sequence analysis by MALDI TOF-TOF mass spectrometry. From our study, seven differentially expressed bacterial proteins (triacylglycerol lipase, N-acetylmuramoyl-L-alanine amidase, flagellin, outer membrane protein A, stringent starvation protein A, 30S ribosomal protein s1 and 60 kDa chaperonin) were identified. Additionally, scanning electron microscope study indicated morphological damages induced on bacterial cell surfaces. To the best of our knowledge, this represents the first time these bacterial proteins are being reported, following treatments with the antibacterial plant extracts. Further studies in this direction could lead to the detailed understanding of their inhibition mechanism and discovery of target-specific antibacterial agents. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. REDOR with a relative full-echo reference

    NASA Astrophysics Data System (ADS)

    Mehta, Anil K.; Cegelski, Lynette; O'Connor, Robert D.; Schaefer, Jacob

    2003-07-01

    REDOR and REDOR-like 13C{ 19F} and 2H{ 19F} NMR experiments have been performed on lyophilized whole cells of Staphylococcus aureus. The bacteria were grown to maturity on media containing L-[ 13C3]alanine or L-[methyl- d3]alanine, and then complexed with the 4-fluorobiphenyl derivative of chloroeremomycin, an analogue of the widely used antibiotic, vancomycin. The position of the 19F of the drug bound in the bacterial cell wall was determined relative to L-alanine 13C and 2H labels in the peptidoglycan peptide stem that was closest to the fluorinated biphenyl moiety of the drug. These determinations were made by dipolar recoupling methods that do not require an absolute measurement of the REDOR full echo (the signal observed without rotor-synchronized dephasing pulses) of the labels in the peptide stem.

  7. Studies on Hydrogen Production by Photosynthetic Bacteria after Anaerobic Fermentation of Starch by a Hyperthermophile, Pyrococcus furiosus

    NASA Astrophysics Data System (ADS)

    Sugitate, Toshihiro; Fukatsu, Makoto; Ishimi, Katsuhiro; Kohno, Hideki; Wakayama, Tatsuki; Nakamura, Yoshihiro; Miyake, Jun; Asada, Yasuo

    In order to establish the sequential hydrogen production from waste starch using a hyperthermophile, Pyrococcus furiosus, and a photosynthetic bacterium, basic studies were done. P. furiosus produced hydrogen and acetate by anaerobic fermentation at 90°C. A photosynthetic bacterium, Rhodobacter sphaeroides RV, was able to produce hydrogen from acetate under anaerobic and light conditions at 30°C. However, Rb. sphaeroides RV was not able to produce hydrogen from acetate in the presence of sodium chloride that was essential for the growth and hydrogen production of P. furiosus although it produced hydrogen from lactate at a reduced rate with 1% sodium chloride. A newly isolated strain, CST-8, from natural environment was, however, able to produce hydrogen from acetate, especially with 3 mM L-alanine and in the presence of 1% sodium chloride. The sequential hydrogen production with P. furiosus and salt-tolerant photosynthetic bacteria could be probable at least in the laboratory experiment scale.

  8. Double-quantum homonuclear rotary resonance: Efficient dipolar recovery in magic-angle spinning nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Nielsen, N. C.; Bildsøe, H.; Jakobsen, H. J.; Levitt, M. H.

    1994-08-01

    We describe an efficient method for the recovery of homonuclear dipole-dipole interactions in magic-angle spinning NMR. Double-quantum homonuclear rotary resonance (2Q-HORROR) is established by fulfilling the condition ωr=2ω1, where ωr is the sample rotation frequency and ω1 is the nutation frequency around an applied resonant radio frequency (rf) field. This resonance can be used for double-quantum filtering and measurement of homonuclear dipolar interactions in the presence of magic-angle spinning. The spin dynamics depend only weakly on crystallite orientation allowing good performance for powder samples. Chemical shift effects are suppressed to zeroth order. The method is demonstrated for singly and doubly 13C labeled L-alanine.

  9. Amine-tethered adsorbents based on three-dimensional macroporous silica for CO(2) capture from simulated flue gas and air.

    PubMed

    Liu, Fa-Qian; Wang, Lei; Huang, Zhao-Ge; Li, Chao-Qin; Li, Wei; Li, Rong-Xun; Li, Wei-Hua

    2014-03-26

    New covalently tethered CO2 adsorbents are synthesized through the in situ polymerization of N-carboxyanhydride (NCA) of l-alanine from amine-functionalized three-dimensional (3D) interconnected macroporous silica (MPS). The interconnected macropores provide low-resistant pathways for the diffusion of CO2 molecules, while the abundant mesopores ensure the high pore volume. The adsorbents exhibit high molecular weight (of up to 13058 Da), high amine loading (more than 10.98 mmol N g(-1)), fast CO2 capture kinetics (t1/2 < 1 min), high adsorption capacity (of up to 3.86 mmol CO2 g(-1) in simulated flue gas and 2.65 mmol CO2 g(-1) in simulated ambient air under 1 atm of dry CO2), as well as good stability over 120 adsorption-desorption cycles, which allows the overall CO2 capture process to be promising and sustainable.

  10. Alkaloids from cyanobacteria with diverse powerful bioactivities.

    PubMed

    Vasas, G; Borbely, G; Nánási, P; Nánási, P P

    2010-09-01

    Alkaloid containing plants represent a heterogeneous group both taxonomically and chemically, a basic nitrogen being the unifying factor for the various classes. As most alkaloids are extremely toxic, organisms containing them do not feature strongly in medicine but they have always been important in the allopathic system. Typical alkaloids are derived from plant sources, they are basic, they contain one or more nitrogen, and they usually have marked physiological actions in humans or other mammalian species. This review will present various alkaloids generated by cyanobacteria, highlighting their complex structures, powerful bioactivities, and pharmacological properties. The main groups of cyanobacterial alkaloids include the neuromuscular transmission blocker anatoxins, the ion channel blocker saxitoxins, the degenerated amino acid β-methylamino-L-alanine, the protein synthesis inhibitor guanidine alkaloid cylindrospermopsins, and cyanobacterial indol alkaloids with antiviral, antifungal, and cytotoxic activity.

  11. Inhibitors of alanine racemase enzyme: a review.

    PubMed

    Azam, Mohammed Afzal; Jayaram, Unni

    2016-08-01

    Alanine racemase is a fold type III PLP-dependent amino acid racemase enzyme catalysing the conversion of l-alanine to d-alanine utilised by bacterial cell wall for peptidoglycan synthesis. As there are no known homologs in humans, it is considered as an excellent antibacterial drug target. The standard inhibitors of this enzyme include O-carbamyl-d-serine, d-cycloserine, chlorovinyl glycine, alaphosphin, etc. d-Cycloserine is indicated for pulmonary and extra pulmonary tuberculosis but therapeutic use of drug is limited due to its severe toxic effects. Toxic effects due to off-target affinities of cycloserine and other substrate analogs have prompted new research efforts to identify alanine racemase inhibitors that are not substrate analogs. In this review, an updated status of known inhibitors of alanine racemase enzyme has been provided which will serve as a rich source of structural information and will be helpful in generating selective and potent inhibitor of alanine racemase.

  12. Locating hydrogen atoms in single crystal and uniaxially aligned amino acids by solid-state NMR

    NASA Astrophysics Data System (ADS)

    Gross, Benjamin J.; McDermott, Ann E.

    2007-03-01

    We demonstrate a novel method to locate hydrogen atoms in amino acids, which involves measuring the C αH α bond vector geometry through orientationally dependent dipolar coupling frequencies measured by Lee-Goldburg cross polarization (LGCP). A 2D LGCP experiment is used to measure the polar angle of the C αH α bond vector in a single crystal of the model compound L-alanine. It is also demonstrated that by coupling the 13C α1H α LGCP experiment to a 13C α15N REDOR experiment, one can determine the complete three-dimensional geometry of the C αH α and C αN vectors in a single crystal. These measurements allow for location of hydrogen atoms in crystalline biological macromolecules.

  13. Radiolysis of alanine adsorbed in a clay mineral

    SciTech Connect

    Aguilar-Ovando, Ellen Y.; Negron-Mendoza, Alicia

    2013-07-03

    Optical activity in molecules is a chemical characteristic of living beings. In this work, we examine the hypothesis of the influence of different mineral surfaces on the development of a specific chirality in organic molecules when subjected to conditions simulating the primitive Earth during the period of chemical evolution. By using X-ray diffraction techniques and HPLC/ELSD to analyze aqueous suspensions of amino acids adsorbed on minerals irradiated in different doses with a cobalt-60 gamma source, the experiments attempt to prove the hypothesis that some solid surfaces (like clays and meteorite rocks) may have a concentration capacity and protective role against external sources of ionizing radiation (specifically {gamma}-ray) for some organic compounds (like some amino acids) adsorbed on them. Preliminary results show a slight difference in the adsorption and radiolysis of the D-and L-alanine.

  14. Deuterium isotope effect on 13C chemical shifts of tetrabutylammonium salts of Schiff bases amino acids.

    PubMed

    Rozwadowski, Z

    2006-09-01

    Deuterium isotope effects on 13C chemical shift of tetrabutylammonium salts of Schiff bases, derivatives of amino acids (glycine, L-alanine, L-phenylalanine, L-valine, L-leucine, L-isoleucine and L-methionine) and various ortho-hydroxyaldehydes in CDCl3 have been measured. The results have shown that the tetrabutylammonium salts of the Schiff bases amino acids, being derivatives of 2-hydroxynaphthaldehyde and 3,5-dibromosalicylaldehyde, exist in the NH-form, while in the derivatives of salicylaldehyde and 5-bromosalicylaldehyde a proton transfer takes place. The interactions between COO- and NH groups stabilize the proton-transferred form through a bifurcated intramolecular hydrogen bond. Copyright (c) 2006 John Wiley & Sons, Ltd.

  15. Anti-cooperative supramolecular polymerization: a new K 2–K model applied to the self-assembly of perylene bisimide dye proceeding via well-defined hydrogen-bonded dimers† †Electronic supplementary information (ESI) available: Synthesis and characterization, NMR and UV/Vis experiments, VPO and ITC measurements, derivation of the K 2–K model. See DOI: 10.1039/c5sc03759j Click here for additional data file.

    PubMed Central

    Gershberg, Jana; Fennel, Franziska; Rehm, Thomas H.; Lochbrunner, Stefan

    2016-01-01

    A perylene bisimide dye bearing amide functionalities at the imide positions derived from amino acid l-alanine and a dialkoxy-substituted benzyl amine self-assembles into tightly bound dimers by π–π-stacking and hydrogen bonding in chloroform. In less polar or unpolar solvents like toluene and methylcyclohexane, and in their mixtures, these dimers further self-assemble into extended oligomeric aggregates in an anti-cooperative process in which even numbered aggregates are highly favoured. The stepwise transition from dimers into oligomers can not be properly described by conventional K 2–K model, and thus a new K 2–K aggregation model has been developed, which interpretes the present anti-cooperative supramolecular polymerization more appropriately. The newly developed K 2–K model will be useful to describe self-assembly processes of a plethora of other π-conjugated molecules that are characterized by a favored dimer species. PMID:28966774

  16. Rapid scan electron paramagnetic resonance at 1.0 GHz of defect centers in γ-irradiated organic solids.

    PubMed

    Shi, Yilin; Rinard, George A; Quine, Richard W; Eaton, Sandra S; Eaton, Gareth R

    2016-02-01

    The radicals in six (60)Co γ-irradiated solids: malonic acid, glycylglycine, 2,6 di-t-butyl 4-methyl phenol, L-alanine, dimethyl malonic acid, and 2-amino isobutyric acid, were studied by rapid scan electron paramagnetic resonance at L-band (1.04 GHz) using a customized Bruker Elexsys spectrometer and a locally-designed dielectric resonator. Sinusoidal scans with widths up to 18.2 mT were generated with the recently described coil driver and Litz wire coils. Power saturation curves showed that the rapid scan signals saturated at higher powers than did conventional continuous wave signals. The rapid scan data were deconvolved and background subtracted to obtain absorption spectra. For the same data acquisition time the signal-to-noise for the absorption spectra obtained in rapid scans were 23 to 37 times higher than for first-derivative spectra obtained by conventional continuous wave electron paramagnetic resonance.

  17. BMAA inhibits nitrogen fixation in the cyanobacterium Nostoc sp. PCC 7120.

    PubMed

    Berntzon, Lotta; Erasmie, Sven; Celepli, Narin; Eriksson, Johan; Rasmussen, Ulla; Bergman, Birgitta

    2013-08-21

    Cyanobacteria produce a range of secondary metabolites, one being the neurotoxic non-protein amino acid β-N-methylamino-L-alanine (BMAA), proposed to be a causative agent of human neurodegeneration. As for most cyanotoxins, the function of BMAA in cyanobacteria is unknown. Here, we examined the effects of BMAA on the physiology of the filamentous nitrogen-fixing cyanobacterium Nostoc sp. PCC 7120. Our data show that exogenously applied BMAA rapidly inhibits nitrogenase activity (acetylene reduction assay), even at micromolar concentrations, and that the inhibition was considerably more severe than that induced by combined nitrogen sources and most other amino acids. BMAA also caused growth arrest and massive cellular glycogen accumulation, as observed by electron microscopy. With nitrogen fixation being a process highly sensitive to oxygen species we propose that the BMAA effects found here may be related to the production of reactive oxygen species, as reported for other organisms.

  18. Previous studies underestimate BMAA concentrations in cycad flour.

    PubMed

    Cheng, Ran; Banack, Sandra Anne

    2009-01-01

    The traditional diet of the Chamorro people of Guam has high concentrations of the neurotoxin BMAA, beta-methyl-amino-L-alanine, in cycad tortillas and from animals that feed on cycad seeds. We measured BMAA concentration in washed cycad flour and compared different extraction methods used by previous researchers in order to determine how much BMAA may have been unaccounted for in prior research. Samples were analyzed with AQC precolumn derivatization using HPLC-FD detection and verified with UPLC-UV, UPLC-MS, and triple quadrupole LC/MS/MS. Although previous workers had studied only the free amino acid component of BMAA in washed cycad flour, we detected significant levels of protein-associated BMAA in washed cycad flour. These data support a link between ALS/PDC and exposure to BMAA.

  19. Amyotrophic lateral sclerosis and environmental factors

    PubMed Central

    Bozzoni, Virginia; Pansarasa, Orietta; Diamanti, Luca; Nosari, Guido; Cereda, Cristina; Ceroni, Mauro

    2016-01-01

    Summary Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder that affects central and peripheral motor neuron cells. Its etiology is unknown, although a relationship between genetic background and environmental factors may play a major role in triggering the neurodegeneration. In this review, we analyze the role of environmental factors in ALS: heavy metals, electromagnetic fields and electric shocks, pesticides, β-N-methylamino-L-alanine, physical activity and the controversial role of sports. The literature on the single issues is analyzed in an attempt to clarify, as clearly as possible, whether each risk factor significantly contributes to the disease pathogenesis. After summarizing conflicting observations and data, the authors provide a final synthetic statement. PMID:27027889

  20. Morphometric and neurochemical alterations found in l-BMAA treated rats.

    PubMed

    de Munck, Estefanía; Muñoz-Sáez, Emma; Miguel, Begoña G; Solas, M Teresa; Martínez, Ana; Arahuetes, Rosa M

    2015-05-01

    Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive muscle paralysis that reflects the motoneurons' degeneration. Several studies support the relationship between β-N-methylamino-l-alanine (l-BMAA), a neurotoxic amino acid produced by cyanobacteria and diatoms, and the sporadic occurrence of ALS and other neurodegenerative diseases. Therefore, the study of its neurotoxicity mechanisms has assumed great relevance in recent years. Recently, our research team has proposed a sporadic ALS animal model by l-BMAA administration in rats, which displays many pathophysiological features of human ALS. In this paper, we deepen the characterization of this model corroborating the occurrence of alterations present in ALS patients such as decreased muscle volume, thinning of the motor cortex, enlarged brain's lateral ventricles, and alteration of both bulbar nuclei and neurotransmitters' levels. Therefore, we conclude that l-BMAA treated rats could be a good model which mimics degenerative features that ALS causes in humans.

  1. Diatoms: a novel source for the neurotoxin BMAA in aquatic environments.

    PubMed

    Jiang, Liying; Eriksson, Johan; Lage, Sandra; Jonasson, Sara; Shams, Shiva; Mehine, Martin; Ilag, Leopold L; Rasmussen, Ulla

    2014-01-01

    Amyotrophic lateral sclerosis (ALS) or Lou Gehrig's disease is a neurological disorder linked to environmental exposure to a non-protein amino acid, β-N-methylamino-L-alanine (BMAA). The only organisms reported to be BMAA-producing, are cyanobacteria--prokaryotic organisms. In this study, we demonstrate that diatoms--eukaryotic organisms--also produce BMAA. Ultra-high-performance liquid chromatography coupled with tandem mass spectrometry revealed the occurrence of BMAA in six investigated axenic diatom cultures. BMAA was also detected in planktonic field samples collected on the Swedish west coast that display an overrepresentation of diatoms relative to cyanobacteria. Given the ubiquity of diatoms in aquatic environments and their central role as primary producers and the main food items of zooplankton, the use of filter and suspension feeders as livestock fodder dramatically increases the risk of human exposure to BMAA-contaminated food.

  2. Multiple neurotoxic items in the Chamorro diet link BMAA with ALS/PDC.

    PubMed

    Banack, Sandra Anne; Murch, Susan J

    2009-01-01

    Beta-methyl-amino-L-alanine, (BMAA), is found in multiple components of the traditional Chamorro diet of Guam and this confounds epidemiological analysis based on a single dietary item. However, using hair as a non-invasive measure of BMAA exposure may help determine risks for developing motor neuron disease. BMAA found in brain tissues of patients with ALS/PDC and not generally in controls suggests that BMAA crosses the blood-brain barrier in patients with disease and is associated with neurodegenerative disease. An examination of frozen versus fixed autopsy tissue from ALS/PDC patients suggests that earlier studies of BMAA in ALS/PDC patients based on fixed tissues may have underestimated the concentration of BMAA in brain tissues. We suggest that the Chamorro people are exposed to chronically low levels of BMAA in the diet and that further research is needed to understand chronic BMAA toxicity.

  3. Screening for non-protein amino acids in seeds of the Guam cycad, Cycas circinalis, by an improved GC-MS method.

    PubMed

    Oh, C H; Brownson, D M; Mabry, T J

    1995-02-01

    The non-protein amino acid, beta-N-methyl-amino-L-alanine (L-BMAA) from Cycas circinalis seeds, has been implicated as a causative agent of amyotrophic lateral sclerosis-Parkinsonism dementia complex (ALS-PDC), a disease known from Guam and other areas in the western Pacific. We analyzed C. circinalis seeds for additional free non-protein amino acids by a recently developed GC-MS method. The samples were prepared by water extraction of seed flour. The amino acids present in the extract were derivatized by N(O,S)-isobutyloxycarbonylation of the amine functional groups and then tert-butyldimethylsilylation of the carboxyl functional groups. Peaks for a total of seventeen derivatives of non-protein amino acids were detected by GC-MS. In addition to L-BMAA, four other non-protein amino acids were identified as beta-alanine, gamma-amino-butyric acid, pyroglutamic acid, and alpha-aminoadipic acid.

  4. Transition-density-fragment interaction approach for exciton-coupled circular dichroism spectra

    NASA Astrophysics Data System (ADS)

    Fujimoto, Kazuhiro J.

    2010-09-01

    A transition-density-fragment interaction (TDFI) method for exciton-coupled circular dichroism (ECCD) spectra is proposed. The TDFI method was previously developed for excitation-energy transfer, which led to the successful estimation of the electronic coupling energy between donor and accepter molecules in xanthorhodopsin [K. J. Fujimoto and S. Hayashi, J. Am. Chem. Soc. 131, 14152 (2009)]. In the present study, the TDFI scheme is extended to the ECCD spectral calculation based on the matrix method and is applied to a dimerized retinal (all-trans N-retinylidene-L-alanine Schiff base) chromophore. Compared with the dipole-dipole and transition charge from ESP methods, TDFI has a much improved description of the electronic coupling. In addition, the matrix method combined with TDFI can reduce the computational costs compared with the full quantum-mechanical calculation. These advantages of the present method make it possible to accurately evaluate the CD Cotton effects observed in experiment.

  5. Supramolecular gelators based on benzenetricarboxamides for ionic liquids.

    PubMed

    Ishioka, Yumi; Minakuchi, Nami; Mizuhata, Minoru; Maruyama, Tatsuo

    2014-02-21

    Supramolecular gelators comprising 1,3,5-benzenetricarboxylic acids and amino acid methyl esters (glycine, L-alanine, L-valine, L-leucine, L-methionine, and L-phenylalanine) for ionic liquids were developed. Ten types of ionic liquids were gelated using the above-mentioned gelators at relatively low concentrations. Field emission-scanning electron microscopy and confocal laser scanning microscopy analyses revealed that these gelators self-assembled into an entangled fibrous structure in ionic liquids, leading to the gelation of the ionic liquids. Comparison studies, involving compounds analogous to the gelators, and Fourier transform infrared spectroscopy measurements suggested that hydrogen bonding played a key role in the self-assembly of the gelator molecules. The ionogels displayed reversible thermal transition characteristics and viscoelastic properties typical of a gel. The gelation of the ionic liquids studied under a wide range of gelator concentrations did not affect the intrinsic conductivity of the ionic liquids.

  6. Biochemistry, genetics and regulation of bacilysin biosynthesis and its significance more than an antibiotic.

    PubMed

    Özcengiz, Gülay; Öğülür, İsmail

    2015-12-25

    Bacillus subtilis has the capacity to produce more than two dozen bioactive compounds with an amazing variety of chemical structures. Among them, bacilysin is a non-ribosomally synthesized dipeptide antibiotic consisting of l-alanine residue at the N terminus and a non-proteinogenic amino acid, l-anticapsin, at the C terminus. In spite of its simple structure, it is active against a wide range of bacteria and fungi. As a potent antimicrobial agent, we briefly review the biochemistry and genetics as well as the regulation of bacilysin biosynthesis within the frame of peptide pheromones-based control of secondary activities. Biological functions of bacilysin in the producer B. subtilis beyond its antimicrobial activity as well as potential biotechnological use of the biosynthetic enzyme l-amino acid ligase (Lal) are also discussed.

  7. FORMATION OF “PROTOPLASTS” OF STAPHYLOCOCCUS AUREUS WITH A FUNGAL N-ACETYLHEXOSAMINIDASE1

    PubMed Central

    Hash, John H.; Wishnick, Marcia; Miller, Philip A.

    1964-01-01

    Hash, John H. (Lederle Laboratories, Pearl River, N.Y.), Marcia Wishnick, and Philip A. Miller. Formation of “protoplasts” of Staphylococcus aureus with a fungal N-acetylhexosaminidase. J. Bacteriol. 87:432–437. 1964.—“Protoplasts” of Staphylococcus aureus were obtained when cells were treated with a fungal N-acetyl-hexosaminidase in hypertonic sucrose solution. The “protoplasts” were sensitive to osmotic shock, and were free of amino sugars and rigid cell walls. They were unable to regenerate cell walls and form colonies. They may be true protoplasts. Osmotic barriers in the “protoplasts” were preserved, and the “protoplasts” incorporated C14-l-alanine at about 60% of the rate of intact cells. Images PMID:14151068

  8. Structure-based design, synthesis and biological evaluation of novel β-secretase inhibitors containing a pyrazole or thiazole moiety as the P3 ligand

    PubMed Central

    Brindisi, Margherita; Yen, Yu-Chen; Xu, Xiaoming; Huang, Xiangping; Devasamudram, Thippeswamy; Bilcer, Geoffrey; Lei, Hui; Koelsch, Gerald; Mesecar, Andrew; Tang, Jordan

    2014-01-01

    We describe structure-based design, synthesis and biological evaluation of a series of novel inhibitors bearing a pyrazole (compounds 3a-h ) or a thiazole moiety (compounds 4a-e) as the P3 ligand. We have also explored Boc-β-amino-L-alanine as a novel P2 ligand. A number of inhibitors have displayed β-secretase inhibitory potency. Inhibitor 4c has shown po tent BACE1 inhibitory activity, Ki = 0.25 nM, cellular EC50 of 194 nM and displayed good selectivity over BACE2. A model of 4c was created based upon the X-ray structure of 2-bound β-Secretase which revealed critical interactions in the active site. PMID:25537272

  9. On the vibrational behavior of single- and double-walled carbon nanotubes under the physical adsorption of biomolecules in the aqueous environment: a molecular dynamics study.

    PubMed

    Ajori, S; Ansari, R; Darvizeh, M

    2016-03-01

    The adsorption of biomolecules on the walls of carbon nanotubes (CNTs) in an aqueous environment is of great importance in the field of nanobiotechnology. In this study, molecular dynamics (MD) simulations were performed to understand the mechanical vibrational behavior of single- and double-walled carbon nanotubes (SWCNTs and DWCNTs) under the physical adsorption of four important biomolecules (L-alanine, guanine, thymine, and uracil) in vacuum and an aqueous environment. It was observed that the natural frequencies of these CNTs in vacuum reduce under the physical adsorption of biomolecules. In the aqueous environment, the natural frequency of each pure CNT decreased as compared to its natural frequency in vacuum. It was also found that the frequency shift for functionalized CNTs as compared to pure CNTs in the aqueous environment was dependent on the radius and the number of walls of the CNT, and could be positive or negative.

  10. Fenton degradation of Cartap hydrochloride: identification of the main intermediates and the degradation pathway.

    PubMed

    Tian, Kaixun; Ming, Cuixiang; Dai, Youzhi; Honore Ake, Kouassi Marius

    2015-01-01

    The advanced oxidation of Cartap hydrochloride (Cartap) promoted by the Fenton system in an aqueous medium was investigated. Based on total organic carbon, chemical oxygen demand and high-performance liquid chromatography, the oxidation of Cartap is quite efficient by the Fenton system. Its long chain is easily destroyed, but the reaction does not proceed to complete mineralization. Ion chromatography detection indicated the formation of acetic acid, propionic acid, formic acid, nitrous acid and sulfuric acid in the reaction mixtures. Further evidence of nitrogen monoxide and sulfur dioxide formation was obtained by using a flue gas analyzer. Monitoring by gas chromatograph-mass spectrometer demonstrated the formation of oxalic acid, ethanol, carbon dioxide, and L-alanine ethylamide. Based on these experimental results, plausible degradation pathways for Cartap mineralization in an aqueous medium by the Fenton system are proposed.

  11. Sequence of Events During Germination of Putrefactive Anaerobe 3679 Spores1

    PubMed Central

    Uehara, Minoru; Frank, Hilmer A.

    1967-01-01

    The sequence of changes during germination of putrefactive anaerobe 3679h spores was studied under aerobic conditions in a solution containing l-alanine and sodium pyrophosphate. Evidence that specific changes occurred in two distinct regions of the spore is given by data on several criteria that were used to measure germination. During the initial stage of germination, the absorbancy decreased, dipicolinic acid was released, the spores lost their resistance to heat and toxic chemicals, and the spore periphery (cortex) darkened gradually under phase-contrast microscopy. The final stage of germination was characterized by changes in the central spore region (core), notably phase darkening of the spore center and stainability with mercurochrome, and by a slight additional absorbancy decrease. Images PMID:4166552

  12. Sequence of events during germination of putrefactive anaerobe 3679 spores.

    PubMed

    Uehara, M; Frank, H A

    1967-09-01

    The sequence of changes during germination of putrefactive anaerobe 3679h spores was studied under aerobic conditions in a solution containing l-alanine and sodium pyrophosphate. Evidence that specific changes occurred in two distinct regions of the spore is given by data on several criteria that were used to measure germination. During the initial stage of germination, the absorbancy decreased, dipicolinic acid was released, the spores lost their resistance to heat and toxic chemicals, and the spore periphery (cortex) darkened gradually under phase-contrast microscopy. The final stage of germination was characterized by changes in the central spore region (core), notably phase darkening of the spore center and stainability with mercurochrome, and by a slight additional absorbancy decrease.

  13. Rapid scan electron paramagnetic resonance at 1.0 GHz of defect centers in γ-irradiated organic solids

    PubMed Central

    Shi, Yilin; Rinard, George A.; Quine, Richard W.; Eaton, Sandra S.; Eaton, Gareth R.

    2016-01-01

    The radicals in six 60Co γ-irradiated solids: malonic acid, glycylglycine, 2,6 di-t-butyl 4-methyl phenol, L-alanine, dimethyl malonic acid, and 2-amino isobutyric acid, were studied by rapid scan electron paramagnetic resonance at L-band (1.04 GHz) using a customized Bruker Elexsys spectrometer and a locally-designed dielectric resonator. Sinusoidal scans with widths up to 18.2 mT were generated with the recently described coil driver and Litz wire coils. Power saturation curves showed that the rapid scan signals saturated at higher powers than did conventional continuous wave signals. The rapid scan data were deconvolved and background subtracted to obtain absorption spectra. For the same data acquisition time the signal-to-noise for the absorption spectra obtained in rapid scans were 23 to 37 times higher than for first-derivative spectra obtained by conventional continuous wave electron paramagnetic resonance. PMID:26834505

  14. Diatoms: A Novel Source for the Neurotoxin BMAA in Aquatic Environments

    PubMed Central

    Lage, Sandra; Jonasson, Sara; Shams, Shiva; Mehine, Martin; Ilag, Leopold L.; Rasmussen, Ulla

    2014-01-01

    Amyotrophic lateral sclerosis (ALS) or Lou Gehrig’s disease is a neurological disorder linked to environmental exposure to a non-protein amino acid, β-N-methylamino-L-alanine (BMAA). The only organisms reported to be BMAA-producing, are cyanobacteria – prokaryotic organisms. In this study, we demonstrate that diatoms – eukaryotic organisms – also produce BMAA. Ultra-high-performance liquid chromatography coupled with tandem mass spectrometry revealed the occurrence of BMAA in six investigated axenic diatom cultures. BMAA was also detected in planktonic field samples collected on the Swedish west coast that display an overrepresentation of diatoms relative to cyanobacteria. Given the ubiquity of diatoms in aquatic environments and their central role as primary producers and the main food items of zooplankton, the use of filter and suspension feeders as livestock fodder dramatically increases the risk of human exposure to BMAA-contaminated food. PMID:24392143

  15. The Transition from Stiff to Compliant Materials in Squid Beaks

    NASA Astrophysics Data System (ADS)

    Miserez, Ali; Schneberk, Todd; Sun, Chengjun; Zok, Frank W.; Waite, J. Herbert

    2008-03-01

    The beak of the Humboldt squid Dosidicus gigas represents one of the hardest and stiffest wholly organic materials known. As it is deeply embedded within the soft buccal envelope, the manner in which impact forces are transmitted between beak and envelope is a matter of considerable scientific interest. Here, we show that the hydrated beak exhibits a large stiffness gradient, spanning two orders of magnitude from the tip to the base. This gradient is correlated with a chemical gradient involving mixtures of chitin, water, and His-rich proteins that contain 3,4-dihydroxyphenyl-L-alanine (dopa) and undergo extensive stabilization by histidyl-dopa cross-link formation. These findings may serve as a foundation for identifying design principles for attaching mechanically mismatched materials in engineering and biological applications.

  16. The transition from stiff to compliant materials in squid beaks.

    PubMed

    Miserez, Ali; Schneberk, Todd; Sun, Chengjun; Zok, Frank W; Waite, J Herbert

    2008-03-28

    The beak of the Humboldt squid Dosidicus gigas represents one of the hardest and stiffest wholly organic materials known. As it is deeply embedded within the soft buccal envelope, the manner in which impact forces are transmitted between beak and envelope is a matter of considerable scientific interest. Here, we show that the hydrated beak exhibits a large stiffness gradient, spanning two orders of magnitude from the tip to the base. This gradient is correlated with a chemical gradient involving mixtures of chitin, water, and His-rich proteins that contain 3,4-dihydroxyphenyl-L-alanine (dopa) and undergo extensive stabilization by histidyl-dopa cross-link formation. These findings may serve as a foundation for identifying design principles for attaching mechanically mismatched materials in engineering and biological applications.

  17. BMAA Inhibits Nitrogen Fixation in the Cyanobacterium Nostoc sp. PCC 7120

    PubMed Central

    Berntzon, Lotta; Erasmie, Sven; Celepli, Narin; Eriksson, Johan; Rasmussen, Ulla; Bergman, Birgitta

    2013-01-01

    Cyanobacteria produce a range of secondary metabolites, one being the neurotoxic non-protein amino acid β-N-methylamino-L-alanine (BMAA), proposed to be a causative agent of human neurodegeneration. As for most cyanotoxins, the function of BMAA in cyanobacteria is unknown. Here, we examined the effects of BMAA on the physiology of the filamentous nitrogen-fixing cyanobacterium Nostoc sp. PCC 7120. Our data show that exogenously applied BMAA rapidly inhibits nitrogenase activity (acetylene reduction assay), even at micromolar concentrations, and that the inhibition was considerably more severe than that induced by combined nitrogen sources and most other amino acids. BMAA also caused growth arrest and massive cellular glycogen accumulation, as observed by electron microscopy. With nitrogen fixation being a process highly sensitive to oxygen species we propose that the BMAA effects found here may be related to the production of reactive oxygen species, as reported for other organisms. PMID:23966039

  18. A complex-polarization-propagator protocol for magneto-chiral axial dichroism and birefringence dispersion.

    PubMed

    Cukras, Janusz; Kauczor, Joanna; Norman, Patrick; Rizzo, Antonio; Rikken, Geert L J A; Coriani, Sonia

    2016-05-21

    A computational protocol for magneto-chiral dichroism and magneto-chiral birefringence dispersion is presented within the framework of damped response theory, also known as complex polarization propagator theory, at the level of time-dependent Hartree-Fock and time-dependent density functional theory. Magneto-chiral dichroism and magneto-chiral birefringence spectra in the (resonant) frequency region below the first ionization threshold of R-methyloxirane and l-alanine are presented and compared with the corresponding results obtained for both the electronic circular dichroism and the magnetic circular dichroism. The additional information content yielded by the magneto-chiral phenomena, as well as their potential experimental detectability for the selected species, is discussed.

  19. Processing of mussel adhesive protein analog thin films by matrix assisted pulsed laser evaporation

    NASA Astrophysics Data System (ADS)

    Cristescu, R.; Patz, T.; Narayan, R. J.; Menegazzo, N.; Mizaikoff, B.; Mihaiescu, D. E.; Messersmith, P. B.; Stamatin, I.; Mihailescu, I. N.; Chrisey, D. B.

    2005-07-01

    Mussel adhesive proteins are a new class of biologically-derived materials that possess unique biocompatibility, bioactivity, and adhesion properties. We have demonstrated successful thin film growth of 3,4-dihydroxyphenyl- L-alanine modified poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (DOPA modified- PEO-PPO-PEO) block copolymer, a mussel adhesive protein analog, using matrix assisted pulsed laser evaporation. We have demonstrated that the main functional groups of the mussel adhesive protein analog are present in the transferred film. The effect of increasing of chain length of the mussel adhesive protein analog on film structure was also examined. These novel polymer thin films could have numerous medical and technological applications if their thin film properties are similar to what is found in bulk. This is the first report of successful MAPLE deposition of this material as thin films.

  20. MAPLE deposition of biomaterial multilayers

    NASA Astrophysics Data System (ADS)

    Califano, Valeria; Bloisi, Francesco; Vicari, Luciano R. M.; Colombi, Paolo; Bontempi, Elza; Depero, Laura E.

    2008-09-01

    Double layers of polyethylene glycol (PEG) and 3-(3,4-dihydroxyphenyl)-2-methyl- L-alanine (m-DOPA) thin films were obtained by matrix assisted pulsed laser evaporation (MAPLE) technique, by depositing a first layer of m-DOPA on Si substrate and a second layer of PEG on top of it. The films were characterized by low angle X-ray diffraction (LAXRD), X-ray reflectivity (XRR), atomic force microscopy (AFM), and micro-Raman spectroscopy. From these analyses it resulted that PEG was deposited without any relevant damage both in terms of chemical structure and molecular weight. Furthermore, PEG chains were mostly in the extended conformation, although PEG micelles appeared.

  1. The influence of manufacture on the free D-amino acid content of Cheddar cheese.

    PubMed

    Csapó, J; Varga-Visi, E; Lóki, K; Albert, Cs

    2006-06-01

    The changes in the concentration and those of composition of alanine, aspartic acid and glutamic acid enantiomers were investigated during manufacture of Cheddar cheese. The amount of D-alanine increased continuously during ripening following the liberation of L-alanine originated from the proteolysis of milk proteins. There was slightly more D-aspartic and D-glutamic acid in the dry matter of curd after pressing than before pressurization. The D-amino acid content and the ratio of the D-enantiomers related to the total amount of free amino acids differed significantly among cheeses produced with different single-strain starters. The D-amino acid composition changed during manufacture, but the influence of the strain selection was not significant on the D-amino acid pattern.

  2. Design of chiral monochloro-s-triazine reagents for the liquid chromatographic separation of amino acid enantiomers.

    PubMed

    Brückner, H; Wachsmann, M

    2003-05-23

    A series of chiral derivatizing reagents (CDRs) was synthesized by nucleophilic replacement of one chlorine atom in cyanuric chloride (2,4,6-trichloro-1,3,5-triazine; s-triazine) by alkoxy (methoxy, butoxy, 1,1,1-trifluoroethoxy) or aryloxy groups (phenoxy, nitrophenoxy, phenylphenoxy, 4-methylcoumaryloxy), and displacement of a second chlorine by L-alanine amide, L-phenylalanine amide, L-proline tert.-butyl ester, or Boc-L-lysine tert.-butyl ester. Further, CDRs were investigated in which two chlorine atoms in cyanuric chloride were substituted consecutively by L-valine amide and L-phenylalanine amide. The resulting CDRs having a remaining reactive chlorine were tested for their capability of derivatizing DL-amino acids followed by liquid chromatographic separation of the resulting diastereomers.

  3. Maintaining network security: how macromolecular structures cross the peptidoglycan layer.

    PubMed

    Scheurwater, Edie M; Burrows, Lori L

    2011-05-01

    Peptidoglycan plays a vital role in bacterial physiology, maintaining cell shape and resisting cellular lysis from high internal turgor pressures. Its integrity is carefully maintained by controlled remodeling during growth and division by the coordinated activities of penicillin-binding proteins, lytic transglycosylases, and N-acetylmuramyl-l-alanine amidases. However, its small pore size (∼2 nm) and covalently closed structure make it a formidable barrier to the assembly of large macromolecular cell-envelope-spanning complexes involved in motility and secretion. Here, we review the strategies used by Gram-negative bacteria to assemble such macromolecular complexes across the peptidoglycan layer, while preserving its essential structural role. In addition, we discuss evidence that suggests that peptidoglycan can be integrated into cell-envelope-spanning complexes as a structural and functional extension of their architecture.

  4. Crystallization and preliminary X-ray analysis of an alanine dehydrogenase from Bacillus megaterium WSH-002.

    PubMed

    Lu, Xiaoyun; Yi, Qiufen; Zhang, Guofang; Zhu, Xianming; Zhou, Honggang; Dong, Hui

    2013-08-01

    Alanine dehydrogenase (L-AlaDH) from Bacillus megaterium WSH-002 catalyses the NAD⁺-dependent interconversion of L-alanine and pyruvate. The enzyme was expressed in Escherichia coli BL21 (DE3) cells and purified with a His6 tag by Ni²⁺-chelating affinity chromatography for X-ray crystallographic analysis. Crystals were grown in a solution consisting of 0.1 M HEPES pH 8.0, 12%(w/v) polyethylene glycol 8000, 8%(v/v) ethylene glycol at a concentration of 15 mg ml⁻¹ purified protein. The crystal diffracted to 2.35 Å resolution and belonged to the trigonal space group R32, with unit-cell parameters a = b = 125.918, c = 144.698 Å.

  5. Exploration of interactions between bioactive solutes and vitamin B9 in aqueous medium by physico-chemical contrivances

    NASA Astrophysics Data System (ADS)

    Nath Roy, Mahendra; Chakraborti, Palash; Ekka, Deepak

    2014-09-01

    Molecular interaction prevailing in α-amino acids (glycine, L-alanine, L-valine) and aqueous solution of folic acid (FA) has been reported by physico-chemical properties as density (ρ), viscosity (η), refractive index (nD) and ultrasonic speed (u) at 298.15 K. The extent of interaction (solute-solvent interaction) is expressed in terms of the limiting apparent molar volume (φ0V), viscosity B-coefficient, molar refraction (RM) and limiting apparent molar adiabatic compressibility (φ0K). The trends in transfer volumes, Δφ0V, have been interpreted in terms of solute-cosolute interactions on the basis of a co-sphere overlap model. The role of the cosolute (FA), and the contribution of solute-solute and solute-solvent interactions to the solution complexes, has also been analysed through the derived properties.

  6. Synergism between hydrogen sulfide (H(2)S) and nitric oxide (NO) in vasorelaxation induced by stonustoxin (SNTX), a lethal and hypotensive protein factor isolated from stonefish Synanceja horrida venom.

    PubMed

    Liew, H C; Khoo, H E; Moore, P K; Bhatia, M; Lu, J; Moochhala, S M

    2007-04-10

    Stonustoxin (SNTX) is a 148 kDa, dimeric, hypotensive and lethal protein factor isolated from the venom of the stonefish Synanceja horrida. SNTX (10-320 ng/ml) progressively causes relaxation of endothelium-intact, phenylephrine (PE)-precontracted rat thoracic aortic rings. The SNTX-induced vasorelaxation was inhibited by L-N(G)-nitro arginine methyl ester (L-NAME), suggesting that nitric oxide (NO) contributes to the SNTX-induced response. Interestingly, D, L-proparglyglycine (PAG) and beta-cyano-L-alanine (BCA), irreversible and competitive inhibitors of cystathionine-gamma-lyase (CSE) respectively, also inhibited SNTX-induced vasorelaxation, indicating that H(2)S may also play a part in the effect of SNTX. The combined use of L-NAME with PAG or BCA showed that H(2)S and NO act synergistically in effecting SNTX-induced vasorelaxation.

  7. In vitro digestion of gliadin by gastrointestinal enzymes and by pyrrolidonecarboxylate peptidase.

    PubMed

    Caldwell, K A

    1980-02-01

    The enzymatic hydrolysis of whole gliadin has been studied in vitro using sequential treatments by pepsin, trypsin, and pancreatin. Amino-terminal pyroglutamic acid-peptides were formed at each stage of the digestion process and the concentration of these peptides increased as the hydrolysis proceeded. Digests were further fractionated on columns of AG 50W-X8 or SE-Sephadex. Enzymic digests and selected column fractions were analyzed with pyrrolidonecarboxylate peptidase. Each digest or fraction was degraded further by this peptidase. Enzyme activity was greatest towards peptic-tryptic-pancreatic digests, peptic-tryptic digests, peptic digests, and undigested gliadin, in that order. The stability of lysosomal membranes to synthetic L-pyroglutamic acid, L-pyroglutamyl-L-alanine, L-pyroglutamyl-L-proline, and to selected fractions of the enzymic digests was tested. Each treatment ruptured lysosomal membranes. Findings are discussed in relation to the normal catabolism of gliadin and the alterations that may occur in certain pathological states.

  8. How similar is the electronic structures of β-lactam and alanine?

    NASA Astrophysics Data System (ADS)

    Chatterjee, Subhojyoti; Ahmed, Marawan; Wang, Feng

    2016-02-01

    The C1s spectra of β-lactam i.e. 2-azetidinone (C3H5NO), a drug and L-alanine (C3H7NO2), an amino acid, exhibit striking similarities, which may be responsible for the competition between 2-azetidinone and the alanyl-alanine moiety in biochemistry. The present study is to reveal the degree of similarities and differences between their electronic structures of the two model molecular pairs. It is found that the similarities in C1s and inner valence binding energy spectra are due to their bonding connections but other properties such as ring structure (in 2-azetidinone) and chiral carbon (alanine) can be very different. Further, the inner valence region of ionization potential greater than 18 eV for 2-azetidinone and alanine is also significantly similar. Finally the strained lactam ring exhibits more chemical reactivity measured at all non-hydrogen atoms by Fukui functions with respect to alanine.

  9. Vibrational averages along thermal lines

    NASA Astrophysics Data System (ADS)

    Monserrat, Bartomeu

    2016-01-01

    A method is proposed for the calculation of vibrational quantum and thermal expectation values of physical properties from first principles. Thermal lines are introduced: these are lines in configuration space parametrized by temperature, such that the value of any physical property along them is approximately equal to the vibrational average of that property. The number of sampling points needed to explore the vibrational phase space is reduced by up to an order of magnitude when the full vibrational density is replaced by thermal lines. Calculations of the vibrational averages of several properties and systems are reported, namely, the internal energy and the electronic band gap of diamond and silicon, and the chemical shielding tensor of L-alanine. Thermal lines pave the way for complex calculations of vibrational averages, including large systems and methods beyond semilocal density functional theory.

  10. Novel electrochemical method for the characterization of the degree of chirality in chiral polyaniline.

    PubMed

    Feng, Zhang; Li, Ma; Yan, Yang; Jihai, Tang; Xiao, Li; Wanglin, Li

    2013-01-01

    A novel method to indicate the degree of chirality in polyaniline (PANI) was developed. The (D-camphorsulfonic acid)- and (HCl)-PANI-based electrodes exhibited significantly different electrochemical performances in D- and L-Alanine (Ala) aqueous solution, respectively, which can be used for the characterization the optical activity of chiral PANI. Cyclic voltammogram, tafel, and open circuit potential of PANI-based electrodes were measured within D- and L-Ala electrolyte solution, respectively. The open circuit potentials under different reacting conditions were analyzed by Doblhofer model formula, in which [C(+)](poly1)/[C(+)](poly2) was used as a parameter to characterize the degree of chirality in chiral PANI. The results showed that [C(+)](poly1)/[C(+)](poly2) can be increased with increasing concentrations of (1S)-(+)- and (1R)-(-)-10-camphorsulfonic acid. In addition, we detected that appropriate response time and lower temperature are necessary to improve the degree of chirality.

  11. The CHAP domain: a large family of amidases including GSP amidase and peptidoglycan hydrolases.

    PubMed

    Bateman, Alex; Rawlings, Neil D

    2003-05-01

    Cleavage of peptidoglycan plays an important role in bacterial cell division, cell growth and cell lysis. Here, we reveal that several known peptidoglycan amidases fall into a family, which includes many proteins of previously unknown function. The family includes two different peptidoglycan cleavage activities: L-muramoyl-L-alanine amidase and D-alanyl-glycyl endopeptidase activity. The family includes the amidase portion of the bifunctional glutathionylspermidine synthase/amidase enzyme from bacteria and pathogenic trypanosomes. The glutathionylspermidine synthase is thought to be a key component of the alternative pathway in trypanosomes for protection from oxygen-radical damage and has been proposed as a potential drug target. The CHAP (cysteine, histidine-dependent amidohydrolases/peptidases) domain is often found in association with other domains that cleave peptidoglycan. The large number of multifunctional hydrolases suggests that they might act in a cooperative manner to cleave specialized substrates.

  12. Metals and the integrity of a biological coating: the cuticle of mussel byssus.

    PubMed

    Holten-Andersen, Niels; Mates, Thomas E; Toprak, Muhammet S; Stucky, Galen D; Zok, Frank W; Waite, J Herbert

    2009-04-09

    The cuticle of mussel byssal threads is a robust natural coating that combines high extensibility with high stiffness and hardness. In this study, fluorescence microscopy and elemental analysis were exploited to show that the 3,4-dihydroxyphenyl-L-alanine (dopa) residues of mussel foot protein-1 colocalize with Fe and Ca distributions in the cuticle of Mytilus galloprovincialis mussel byssal threads. Chelated removal of Fe and Ca from the cuticle of intact threads resulted in a 50% reduction in cuticle hardness, and thin sections subjected to the same treatment showed a disruption of cuticle integrity. Dopa-metal complexes may provide significant interactions for the integrity of composite cuticles deformed under tension.

  13. First observation of natural circular dichroism spectra in the extreme ultraviolet region using a polarizing undulator-based optical system and its polarization characteristics.

    PubMed

    Tanaka, Masahito; Yagi-Watanabe, Kazutoshi; Kaneko, Fusae; Nakagawa, Kazumichi

    2009-07-01

    Natural circular dichroism (CD) spectra in the extreme ultraviolet (EUV) region down to a wavelength of 80 nm have been observed for the first time, using an alanine thin film deposited on sodium salicylate coated glass as a sample. Calibrated EUV-CD spectra of L-alanine exhibited a large negative peak at around 120 nm and a positive CD signal below 90 nm, which were roughly predicted by theoretical calculations. A CD measurement system with an Onuki-type polarizing undulator was used to obtain the EUV-CD spectra. This CD system, the development of which took five years, can be used to observe even weak natural CD spectra. The polarization characteristics of this system were also evaluated in order to calibrate the recorded CD spectra.

  14. Kinetics of acid hydrolysis and reactivity of some antibacterial hydrophilic iron(II) imino-complexes

    NASA Astrophysics Data System (ADS)

    Shaker, Ali Mohamed; Nassr, Lobna Abdel-Mohsen Ebaid; Adam, Mohamed Shaker Saied; Mohamed, Ibrahim Mohamed Abdelhalim

    2015-05-01

    Kinetic study of acid hydrolysis of some hydrophilic Fe(II) Schiff base amino acid complexes with antibacterial properties was performed using spectrophotometry. The Schiff base ligands were derived from sodium 2-hydroxybenzaldehyde-5-sulfonate and glycine, L-alanine, L-leucine, L-isoleucine, DL-methionine, DL-serine, or L-phenylalanine. The reaction was studied in aqueous media under conditions of pseudo-first order kinetics. Moreover, the acid hydrolysis was studied at different temperatures and the activation parameters were calculated. The general rate equation was suggested as follows: rate = k obs [Complex], where k obs = k 2 [H+]. The evaluated rate constants and activation parameters are consistent with the hydrophilicity of the investigated complexes.

  15. 1-Deoxysphingolipids Encountered Exogenously and Made de Novo: Dangerous Mysteries inside an Enigma*

    PubMed Central

    Duan, Jingjing; Merrill, Alfred H.

    2015-01-01

    The traditional backbones of mammalian sphingolipids are 2-amino, 1,3-diols made by serine palmitoyltransferase (SPT). Many organisms additionally produce non-traditional, cytotoxic 1-deoxysphingoid bases and, surprisingly, mammalian SPT biosynthesizes some of them, too (e.g. 1-deoxysphinganine from l-alanine). These are rapidly N-acylated to 1-deoxy-“ceramides” with very uncommon biophysical properties. The functions of 1-deoxysphingolipids are not known, but they are certainly dangerous as contributors to sensory and autonomic neuropathies when elevated by inherited SPT mutations, and they are noticeable in diabetes, non-alcoholic steatohepatitis, serine deficiencies, and other diseases. As components of food as well as endogenously produced, these substances are mysteries within an enigma. PMID:25947379

  16. The Stability of Right- and Left-Handed Alpha-Helices as a Function of Monomer Chirality

    SciTech Connect

    Lins, Roberto D.; Ferreira, Ricardo

    2006-10-01

    A few years ago Milton, Milton and Kent1 described the total synthesis of the enzyme HIV-1 protease starting from D-amino acids. They found2 that the α-helices of the synthetic D-protease are left-handed, in contrast with the α-helices of the standard (L-amino acids) proteins, which are, of course, right-handed3. At present it is possible to study the stabilities of homochiral and mixed protein structures with the help of computer simulation techniques4,5. For example, using molecular mechanics calculations with the AMBER force field it was possible to show that DL-alanine in right-handed α-helices is 21.3 ± 3.4 kcal mol-1 less stable than right-handed α-helices made from L-alanine6. In the present paper we describe very accurate calculations which gives strong support to these findings.

  17. Preparation and application of abietic acid-derived optically active helical polymers and their chiral hydrogels.

    PubMed

    Yao, Fei; Zhang, Dongyue; Zhang, Chaohong; Yang, Wantai; Deng, Jianping

    2013-02-01

    A novel chiral monomer N-propargyl abietamide, M1, was synthesized from abietic acid and catalytically polymerized with (nbd)Rh+B-(C6H5)4 (nbd=norbornadiene), providing polymer [poly(1)] with a molecular weight of 13,000-36,000 at a yield of 59-84%. Poly(1) did not form stable helices in tetrahydrofuran at room temperature whereas copolymerization of M1 and the achiral N-propargylamide monomer, M2, led to the formation of helical optically active copolymers as indicated by circular dichroism studies, UV-vis spectroscopy, and specific optical rotation measurements. Hydrogels were prepared based on an optically active helical copolymer, poly(M1(0.32)-co-M2(0.68)) that exhibited enantioselective recognition toward l-alanine. The novel chiral polymers derived from abietic acid are expected to find applications in such areas as chiral recognition, chiral resolution, and chiral catalysis.

  18. Synthesis, characterization of α-amino acid Schiff base derived Ru/Pt complexes: Induces cytotoxicity in HepG2 cell via protein binding and ROS generation

    NASA Astrophysics Data System (ADS)

    Alsalme, Ali; Laeeq, Sameen; Dwivedi, Sourabh; Khan, Mohd. Shahnawaz; Al Farhan, Khalid; Musarrat, Javed; Khan, Rais Ahmad

    2016-06-01

    We have synthesized two new complexes of platinum (1) and ruthenium (2) with α-amino acid, L-alanine, and 2,3-dihydroxybenzaldehyde derived Schiff base (L). The ligand and both complexes were characterized by using elemental analysis and several other spectroscopic techniques viz; IR, 1H, 13C NMR, EPR, and ESI-MS. Furthermore, the protein-binding ability of synthesized complexes was monitored by UV-visible, fluorescence and circular dichroism techniques with a model protein, human serum albumin (HSA). Both the PtL2 and RuL2 complexes displayed significant binding towards HSA. Also, in vitro cytotoxicity assay for both complexes was carried out on human hepatocellular carcinoma cancer (HepG2) cell line. The results showed concentration-dependent inhibition of cell viability. Moreover, the generation of reactive oxygen species was also evaluated, and results exhibited substantial role in cytotoxicity.

  19. Structure-based design, synthesis and biological evaluation of novel β-secretase inhibitors containing a pyrazole or thiazole moiety as the P3 ligand.

    PubMed

    Ghosh, Arun K; Brindisi, Margherita; Yen, Yu-Chen; Xu, Xiaoming; Huang, Xiangping; Devasamudram, Thippeswamy; Bilcer, Geoffrey; Lei, Hui; Koelsch, Gerald; Mesecar, Andrew D; Tang, Jordan

    2015-02-01

    We describe structure-based design, synthesis, and biological evaluation of a series of novel inhibitors bearing a pyrazole (compounds 3a-h) or a thiazole moiety (compounds 4a-e) as the P3 ligand. We have also explored Boc-β-amino-l-alanine as a novel P2 ligand. A number of inhibitors have displayed β-secretase inhibitory potency. Inhibitor 4c has shown potent BACE1 inhibitory activity, Ki=0.25nM, cellular EC50 of 194nM, and displayed good selectivity over BACE2. A model of 4c was created based upon the X-ray structure of 2-bound β-secretase which revealed critical interactions in the active site.

  20. Cyanobacterial blooms and biomagnification of the neurotoxin BMAA in South Florida coastal waters

    NASA Astrophysics Data System (ADS)

    Brand, L.; Mash, D.

    2008-12-01

    Blooms of cyanobacteria have developed in Florida Bay, Biscayne Bay and other coastal waters of South Florida. It has recently been shown that virtually all cyanobacteria produce the potent neurotoxin, beta-N- methylamino-L-alanine (BMAA). Studies in Guam indicate that BMAA can biomagnify up the food chain from cyanobacteria to human food and humans. Recent studies in Guam and on human brains in North America suggest an association between BMAA and neurodegenerative diseases such as Alzheimer's, Parkinson's, and Amyotrophic Lateral Sclerosis (ALS). A variety of organisms from South Florida coastal waters are being analyzed for BMAA content to determine if BMAA is biomagnifying in these food chains and if it is a potential human health hazard. Some have extremely high concentrations of BMAA.

  1. Analysis of the E. coli NifS CsdB protein at 2.0 A reveals the structural basis for perselenide and persulfide intermediate formation.

    PubMed

    Lima, Christopher D

    2002-02-01

    The Escherichia coli NifS CsdB protein is a member of the homodimeric pyridoxal 5'-phosphate (PLP)-dependent family of enzymes. These enzymes are capable of decomposing cysteine or selenocysteine into L-alanine and sulfur or selenium, respectively. E. coli NifS CsdB has a high specificity for L-selenocysteine in comparison to l-cysteine, suggesting a role for this enzyme is selenium metabolism. The 2.0 A crystal structure of E. coli NifS CsdB reveals a high-resolution view of the active site of this enzyme in apo-, persulfide, perselenide, and selenocysteine-bound intermediates, suggesting a mechanism for the stabilization of the enzyme persulfide and perselenide intermediates during catalysis, a necessary intermediate in the formation of sulfur and selenium containing metabolites. Copyright 2002 Elsevier Science Ltd.

  2. Probing micro-solvation in "numbers": the case of neutral dipeptides in water.

    PubMed

    Takis, Panteleimon G; Papavasileiou, Konstantinos D; Peristeras, Loukas D; Melissas, Vasilios S; Troganis, Anastassios N

    2013-05-21

    How many solvent molecules and in what way do they interact directly with biomolecules? This is one of the most challenging questions regarding a deep understanding of biomolecular functionalism and solvation. We herein present a novel NMR spectroscopic study, achieving for the first time the quantification of the directly interacting water molecules with several neutral dipeptides. Our proposed method is supported by both molecular dynamics simulations and density functional theory calculations, advanced analysis of which allowed the identification of the direct interactions between solute-solvent molecules in the zwitterionic L-alanyl-L-alanine dipeptide-water system. Beyond the quantification of dipeptide-water molecule direct interactions, this NMR technique could be useful for the determination and elucidation of small to moderate bio-organic molecular groups' direct interactions with various polar solvent molecules, shedding light on the biomolecular micro-solvation processes and behaviour in various solvents.

  3. In Vitro Destruction of Streptococcus pneumoniae Biofilms with Bacterial and Phage Peptidoglycan Hydrolases▿

    PubMed Central

    Domenech, Mirian; García, Ernesto; Moscoso, Miriam

    2011-01-01

    Host- and phage-coded cell wall hydrolases have been used to fight Streptococcus pneumoniae growing as planktonic cells in vitro as well as in animal models. Until now, however, the usefulness of these enzymes in biofilm-grown pneumococci has gone untested. The antipneumococcal activity of different cell wall hydrolases produced by S. pneumoniae and a number of its phages was examined in an in vitro biofilm model. The major pneumococcal autolysin LytA, an N-acetylmuramoyl-l-alanine amidase, showed the greatest efficiency in disintegrating S. pneumoniae biofilms. The phage-encoded lysozymes Cpl-1 and Cpl-7 were also very efficient. Biofilms formed by the close pneumococcal relatives Streptococcus pseudopneumoniae and Streptococcus oralis were also destroyed by the phage endolysins but not by the S. pneumoniae autolysin LytA. A cooperative effect of LytA and Cpl-1 in the disintegration of S. pneumoniae biofilms was recorded. PMID:21746941

  4. Investigation of biomolecules trapped in fluid inclusions inside halite crystals by Raman spectroscopy.

    PubMed

    Osterrothová, Kateřina; Jehlička, Jan

    2011-12-01

    Raman spectroscopy was tested for the identification of biomolecules (glycine, L-alanine, β-alanine, L-serine, and γ-aminobutyric acid) trapped in fluid inclusions inside halite model crystals. The investigated biomolecules represent important targets for future astrobiological missions. We know from terrestrial conditions that organic molecules and microorganisms can be sealed within fluid inclusions and can survive intact even for hundreds of millions of years. Raman spectroscopy is currently being miniaturized for future extraterrestrial planetary exploration (ExoMars 2018). Raman spectroscopy has shown the ability to detect investigated aminoacids nondestructively without any sample preparation, in short measurement times, and in relatively low concentrations. The number of registered Raman bands of investigated aminoacids and their intensity clearly correlate with the given concentration of biomolecules within fluid inclusions. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. Acquisition of Raman spectra of amino acids using portable instruments: outdoor measurements and comparison.

    PubMed

    Culka, A; Jehlička, J; Edwards, H G M

    2010-12-01

    Raman spectra of 13 amino acids: L-alanine, β-alanine, L-asparagine, L-aspartic acid, L-glutamic acid, L-glutamine, glycine, L-methionine, L-proline, L-serine, L-threonine, L-tryptophan and L-tyrosine were acquired outdoors using two portable Raman instruments from the Ahura and Delta Nu manufacturers, both with 785 nm laser excitation. Both instruments provide quality Raman spectra with nevertheless a variable dependence upon the prevailing experimental conditions. The data acquired in these experiments will inform the selection of suitable Raman spectrometers for the in-field detection of biomolecules of relevance to the search for life signatures spectroscopically in terrestrial extreme environments and in extraterrestrial exploration, especially of planetary surfaces and subsurfaces using robotic instrumentation. Copyright © 2010 Elsevier B.V. All rights reserved.

  6. Chemical activation of a high-affinity glutamate transporter in human erythrocytes and its implications for malaria-parasite-induced glutamate uptake.

    PubMed

    Winterberg, Markus; Rajendran, Esther; Baumeister, Stefan; Bietz, Sven; Kirk, Kiaran; Lingelbach, Klaus

    2012-04-12

    Human erythrocytes have a low basal permeability to L-glutamate and are not known to have a functional glutamate transporter. Here, treatment of human erythrocytes with arsenite was shown to induce the uptake of L-glutamate and D-aspartate, but not that of D-glutamate or L-alanine. The majority of the arsenite-induced L-glutamate influx was via a high-affinity, Na(+)-dependent system showing characteristics of members of the "excitatory amino acid transporter" (EAAT) family. Western blots and immunofluorescence assays revealed the presence of a member of this family, EAAT3, on the erythrocyte membrane. Erythrocytes infected with the malaria parasite Plasmodium falciparum take up glutamate from the extracellular environment. Although the majority of uptake is via a low-affinity Na(+)-independent pathway there is, in addition, a high-affinity uptake component, raising the possibility that the parasite activates the host cell glutamate transporter.

  7. Polypeptides in alpha-helix conformation perform as diodes.

    PubMed

    Cristancho, Dahiyana; Seminario, Jorge M

    2010-02-14

    Molecules that resemble a semiconductor diode depletion zone are those with an intrinsic electric dipole, which were suggested as potential electronic devices. However, so far, no single molecule has met such a goal because any electron donor-acceptor linker strongly diminishes any possibility of diode behavior. We find an intrinsic diode behavior in polypeptides such as poly(L-alanine) and polyglycine in alpha-helix conformation, explained in terms of molecular orbital theory using ab initio methods. The application of an antiparallel electric field with respect to the molecular dipole yields a gradual increase in current through the junction because the valence and conduction orbitals approach each other reducing their gap as the bias increases. However, a parallel field makes the gap energy increase, avoiding the pass of the electrons.

  8. Investigation of biomolecules trapped in fluid inclusions inside halite crystals by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Osterrothová, Kateřina; Jehlička, Jan

    2011-12-01

    Raman spectroscopy was tested for the identification of biomolecules (glycine, L-alanine, β-alanine, L-serine, and γ-aminobutyric acid) trapped in fluid inclusions inside halite model crystals. The investigated biomolecules represent important targets for future astrobiological missions. We know from terrestrial conditions that organic molecules and microorganisms can be sealed within fluid inclusions and can survive intact even for hundreds of millions of years. Raman spectroscopy is currently being miniaturized for future extraterrestrial planetary exploration (ExoMars 2018). Raman spectroscopy has shown the ability to detect investigated aminoacids nondestructively without any sample preparation, in short measurement times, and in relatively low concentrations. The number of registered Raman bands of investigated aminoacids and their intensity clearly correlate with the given concentration of biomolecules within fluid inclusions.

  9. Theoretical investigation of the optical and EPR parameters for VO 2+ion in some complexes

    NASA Astrophysics Data System (ADS)

    Kalfaoğlu, Emel; Karabulut, Bünyamin

    2012-04-01

    The molecular orbital coefficients and the EPR parameters of trisodium citrate dihydrate, sodium hydrogen oxalate monohydrate, potassium d-gluconate monohydrate and L-Alanine vanadyl complexes are calculated theoretically. Two d-d transition spectra and EPR parameters for the VO2+ complex are calculated theoretically by using crystal-field theory. The calculated g and A paramaters have indicated that paramagnetic center is axially symmetric. Having the relations of g∥A⊥ for VO2+ ions, it can be concluded that VO2+ ions are located in distorted octahedral sites (C4v) elongated along the z-axis and the ground state of the paramagnetic electron is dxy.

  10. Chirality Amplification in Tactoids of Lyotropic Chromonic Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Peng, Chenhui; Lavrentovich, Oleg

    2014-03-01

    We demonstrate an effective chirality amplification based on the long-range forces, extending over the scales of tens of micrometers, much larger than the single molecule (nanometer) scale. The mechanism is rooted in the long-range elastic nature of orientational order in lyotropic chromonic liquid crystals (LCLCs) that represent water solutions of achiral disc-like molecules. Minute quantities of chiral molecules such as amino acid L-alanine and limonene added to the droplets of LCLC lead to chiral amplification characterized by an increase of optical activity by a factor of 103 - 104. This effect allows one to discriminate and detect the absolute configuration of chiral molecules in an aqueous system, thus opening new possibilities in biosensing and other biological applications.

  11. Crystal growth, structural and thermal studies of amino acids admixtured L-arginine phosphate monohydrate single crystals

    NASA Astrophysics Data System (ADS)

    Anandan, P.; Saravanan, T.; Parthipan, G.; Kumar, R. Mohan; Bhagavannarayana, G.; Ravi, G.; Jayavel, R.

    2011-05-01

    To study the improved characteristics of L-arginine phosphate monohydrate (LAP) crystals, amino acids mixed LAP crystals have been grown by slow cooling method. Amino acids like glycine, L-alanine, and L-valine have been selected for doping. Optical quality bulk crystals have been harvested after a typical growth period of about twenty days. The effect of amino acids in the crystal lattice and molecular vibrational frequencies of various functional groups in the crystals have been studied using X-ray powder diffraction and Fourier Transform infrared (FTIR) analyses respectively. Thermal behavior of the amino acids mixed LAP crystals have been studied from the TG and DTG analyses. High-resolution X-ray diffraction studies have been carried out to find the crystalline nature. Optical transmission studies have been carried out by UV-vis spectrophotometer. The cut off wavelength is below 240 nm for the grown crystals.

  12. N-( p-Ethynylbenzoyl) derivatives of amino acid and dipeptide methyl esters - Synthesis and structural study

    NASA Astrophysics Data System (ADS)

    Eißmann, Frank; Weber, Edwin

    2011-11-01

    A series of N-( p-ethynylbenzoyl) derivatives ( 1-4) of the amino acids glycine and L-alanine as well as the dipeptides glycylglycine and L-alanylglycine has been synthesized via a two-step reaction sequence including the reaction of an appropriate N-( p-bromobenzoyl) precursor with trimethylsilylacetylene followed by deprotection of the trimethylsilyl protecting group, respectively. X-ray crystal structures of the amino acid and dipeptide methyl esters 1-4 are reported. The amide and peptide bonds within each molecular structure are planar and adopt the trans-configuration. The packing structures are governed by N sbnd H⋯O interactions leading to the formation of characteristic strand motifs. Further stabilization results from weaker C sbnd H⋯O and C sbnd H⋯π contacts.

  13. Water structure around peptide fragments in aqueous solutions

    SciTech Connect

    McLain, Sylvia E; Soper, Alan K; Watts, Prof Anthony

    2008-01-01

    The bulk water structure around small peptide fragments - glycyl-L-alanine, glycyl-L-proline and L-alanyl-L-proline - has been determined by a combination of neutron diffraction with isotopic substitution and empirical potential structural refinement techniques. The addition of each of the dipeptides to water yields a decreased water-water coordination in the surrounding water solvent. Additionally both the Ow-Ow radial distribution functions and the water-water spatial density functions in all of the solutions indicate an electrostrictive effect in the second water coordination shell of the bulk water network. This effect is not observed in similar experiments on the amino acid L-proline alone in solution, which is one component of two of the peptides measured here.

  14. Enhanced sensitivity in high-resolution 1H solid-state NMR spectroscopy with DUMBO dipolar decoupling under ultra-fast MAS

    NASA Astrophysics Data System (ADS)

    Salager, Elodie; Stein, Robin S.; Steuernagel, Stefan; Lesage, Anne; Elena, Bénédicte; Emsley, Lyndon

    2009-02-01

    The solid-state NMR 1H homonuclear decoupling sequences in the DUMBO family are shown to be effective at ultra-fast MAS rates of up to 65 kHz. The sequences are applied to model compounds glycine and [2- 13C]- L-alanine as well as the dipeptide β- L-Asp- L-Ala in windowed and continuous phase-modulated versions. They are shown to achieve especially impressive resolution when implemented in a 2D constant-time experiment. At 65 kHz MAS, 1H resolution using homonuclear decoupling is similar to that obtained at lower MAS rates, but peak intensity, and therefore spectral sensitivity, is improved by a factor of 5 over homonuclear-decoupled spectra at 10 kHz MAS.

  15. 1-Deoxysphingolipids Encountered Exogenously and Made de Novo: Dangerous Mysteries inside an Enigma.

    PubMed

    Duan, Jingjing; Merrill, Alfred H

    2015-06-19

    The traditional backbones of mammalian sphingolipids are 2-amino, 1,3-diols made by serine palmitoyltransferase (SPT). Many organisms additionally produce non-traditional, cytotoxic 1-deoxysphingoid bases and, surprisingly, mammalian SPT biosynthesizes some of them, too (e.g. 1-deoxysphinganine from L-alanine). These are rapidly N-acylated to 1-deoxy-"ceramides" with very uncommon biophysical properties. The functions of 1-deoxysphingolipids are not known, but they are certainly dangerous as contributors to sensory and autonomic neuropathies when elevated by inherited SPT mutations, and they are noticeable in diabetes, non-alcoholic steatohepatitis, serine deficiencies, and other diseases. As components of food as well as endogenously produced, these substances are mysteries within an enigma.

  16. ESR study of some gamma irradiated amino acids and condensed 1,4-dihydropyridines

    NASA Astrophysics Data System (ADS)

    Aydın, Murat; Şimşek, Rahime; Gündüz, Miyase Gözde; Şafak, Cihat; Osmanoğlu, Y. Emre

    2013-03-01

    L-alanine methyl ester hydrochloride, 2-aminoisobutyric acid and some condensed 1,4-dihydropyridine derivatives (Compounds R1-R4) were gamma irradiated, the induced free radicals was investigated at room temperature by electron spin resonance techniques. The observed paramagnetic species of amino acids compounds were attributed to the CH3ĊHCOOCH3 and (CH3)2ĊCOOH radicals, respectively. The observed spectra of the 1,4-dihydropyridine derivatives interpreted in terms of some type of amine radical fragments. The spectra were computer simulated and the g values of the radicals and the hyperfine structure constants of the unpaired electron with nearby protons and 14N nucleus were determined. In this study, the observed paramagnetic species were found to be stable at room temperature more than 2 months.

  17. Line-narrowing in proton-detected nitrogen-14 NMR

    NASA Astrophysics Data System (ADS)

    Cavadini, Simone; Vitzthum, Veronika; Ulzega, Simone; Abraham, Anuji; Bodenhausen, Geoffrey

    2010-01-01

    In solids spinning at the magic angle, the indirect detection of single-quantum (SQ) and double-quantum (DQ) 14N spectra ( I = 1) via spy nuclei S = 1/2 such as protons can be achieved in the manner of heteronuclear single- or multiple-quantum correlation (HSQC or HMQC) spectroscopy. The HMQC method relies on the excitation of two-spin coherences of the type T11IT11S and T21IT11S at the beginning of the evolution interval t1. The spectra obtained by Fourier transformation from t1 to ω1 may be broadened by the homogenous decay of the transverse terms of the spy nuclei S. This broadening is mostly due to homonuclear dipolar S- S' interactions between the proton spy nuclei. In this work we have investigated the possibility of inserting rotor-synchronized symmetry-based C or R sequences and decoupling schemes such as Phase-Modulated Lee-Goldburg (PMLG) sequences in the evolution period. These schemes reduce the homonuclear proton-proton interactions and lead to an enhancement of the resolution of both SQ and DQ proton-detected 14N HMQC spectra. In addition, we have investigated the combination of HSQC with symmetry-based sequences and PMLG and shown that the highest resolution in the 14N dimension is achieved by using HSQC in combination with symmetry-based sequences of the R-type. We show improvements in resolution in samples of L-alanine and the tripeptide ala-ala-gly (AAG). In particular, for L-alanine the width of the 14N SQ peak is reduced from 2 to 1.2 kHz, in agreement with simulations. We report accurate measurements of quadrupolar coupling constants and asymmetry parameters for amide 14N in AAG peptide bonds.

  18. Gustatory responsiveness to the 20 proteinogenic amino acids in the spider monkey (Ateles geoffroyi).

    PubMed

    Larsson, Jenny; Maitz, Anna; Hernandez Salazar, Laura Teresa; Laska, Matthias

    2014-03-29

    The gustatory responsiveness of four adult spider monkeys to the 20 proteinogenic amino acids was assessed in two-bottle preference tests of brief duration (1min). We found that Ateles geoffroyi responded with significant preferences for seven amino acids (glycine, l-proline, l-alanine, l-serine, l-glutamic acid, l-aspartic acid, and l-lysine) when presented at a concentration of 100mM and/or 200mM and tested against water. At the same concentrations, the animals significantly rejected five amino acids (l-tryptophan, l-tyrosine, l-valine, l-cysteine, and l-isoleucine) and were indifferent to the remaining tastants. Further, the results show that the spider monkeys discriminated concentrations as low as 0.2mM l-lysine, 2mM l-glutamic acid, 10mM l-proline, 20mM l-valine, 40mM glycine, l-serine, and l-aspartic acid, and 80mM l-alanine from the alternative stimulus, with individual animals even scoring lower threshold values. A comparison between the taste qualities of the proteinogenic amino acids as described by humans and the preferences and aversions observed in the spider monkeys suggests a fairly high degree of agreement in the taste quality perception of these tastants between the two species. A comparison between the taste preference thresholds obtained with the spider monkeys and taste detection thresholds reported in human subjects suggests that the taste sensitivity of A. geoffroyi for the amino acids tested here might match that of Homo sapiens. The results support the assumption that the taste responses of spider monkeys to proteinogenic amino acids might reflect an evolutionary adaptation to their frugivorous and thus protein-poor diet.

  19. Microwave Heating of Synthetic Skin Samples for Potential Treatment of Gout Using the Metal-Assisted and Microwave-Accelerated Decrystallization Technique

    PubMed Central

    2016-01-01

    Physical stability of synthetic skin samples during their exposure to microwave heating was investigated to demonstrate the use of the metal-assisted and microwave-accelerated decrystallization (MAMAD) technique for potential biomedical applications. In this regard, optical microscopy and temperature measurements were employed for the qualitative and quantitative assessment of damage to synthetic skin samples during 20 s intermittent microwave heating using a monomode microwave source (at 8 GHz, 2–20 W) up to 120 s. The extent of damage to synthetic skin samples, assessed by the change in the surface area of skin samples, was negligible for microwave power of ≤7 W and more extensive damage (>50%) to skin samples occurred when exposed to >7 W at initial temperature range of 20–39 °C. The initial temperature of synthetic skin samples significantly affected the extent of change in temperature of synthetic skin samples during their exposure to microwave heating. The proof of principle use of the MAMAD technique was demonstrated for the decrystallization of a model biological crystal (l-alanine) placed under synthetic skin samples in the presence of gold nanoparticles. Our results showed that the size (initial size ∼850 μm) of l-alanine crystals can be reduced up to 60% in 120 s without damage to synthetic skin samples using the MAMAD technique. Finite-difference time-domain-based simulations of the electric field distribution of an 8 GHz monomode microwave radiation showed that synthetic skin samples are predicted to absorb ∼92.2% of the microwave radiation. PMID:27917407

  20. Effects of straight alkyl chain, extra hydroxylated alkyl chain and branched chain amino acids on gastric emptying evaluated using a non-invasive breath test in conscious rats

    PubMed Central

    Uchida, Masayuki; Kobayashi, Orie; Iwasawa, Kaori; Shimizu, Kimiko

    2016-01-01

    Aim: Some amino acids been known to influence gastric emptying. Thus we have evaluated the effects of straight alkyl chain, extra hydroxylated alkyl chain and branched chain amino acids on gastric emptying. Materials and Methods: Gastric emptying was evaluated in rats after feeding with Racol (nutrient formulae) containing [1-13C] acetic acid. Using a breath test, the content of 13CO2 in their expired air was measured by infrared analyzers. Rats were orally administered with test amino acids, while control rats were administered orally with distilled water. Results: The expired 13CO2 content in the expired air increased with time, peaked after about 30 min and decreased thereafter. Among the amino acids having an alkyl chain, l-serine, l-alanine and l-glycine, significantly decreased the 13CO2 content and Cmax, and delayed Tmax, suggesting inhibition and delay of gastric emptying. AUC120 min values of l-alanine and l-glycine also decreased significantly. l-Threonine significantly decreased 13CO2 content and delayed Tmax, but had no influence on Cmax and AUC120 min values, suggesting a delay of gastric emptying. l-Isoleucine and l-leucine and l-valine significantly decreased 13CO2 content, suggesting inhibition of the gastric emptying, but Cmax, Tmax and AUC120 min values were not significantly affected. Conclusion: The results show that the amino acids used in the present study had different effects on gastric emptying. Moreover, it was found that inhibition and delay of gastric emptying were clearly classifiable by analyzing the change in 13CO2 content of the expired air and the Cmax, Tmax and AUC120 min values. PMID:27169776

  1. Characterization of free and alginate-polylysine-alginate microencapsulated Erwinia herbicola for the conversion of ammonia, pyruvate, and phenol into L-tyrosine

    SciTech Connect

    Lloyd-George, I.; Chang, T.M.S.

    1995-12-20

    The whole cell tyrosine phenol-lyase activity of Erwinia herbicola was microencapsulated. The authors studied the use of this for the conversion of ammonia and pyruvate along with phenol or catechol, respectively, into L-tyrosine or dihydroxyphenyl-L-alanine (L-dopa). The reactions are relevant to the development of new methods for the production of L-tyrosine and L-dopa. The growth of E. herbicola at temperatures from 22 C to 32 C is stable, since at these temperatures the cells grow up to the stationary phase and remain there for at least 10 h. At 37 C the cells grow rapidly, but they also enter the death phase rapidly. There is only limited growth of E. herbicola at 42 C. Whole cells of E. herbicola were encapsulated within alginate-polylysine-alginate microcapsules (916 {+-} 100 {micro}m, mean {+-} std. dev.). The TPL activity of the cells catalyzed the production of L-tyrosine or dihydroxyphenol-L-alanine (L-dopa) from ammonia, pyruvate, and phenol or catechol, respectively. In the production of tyrosine, an integrated equation based on an ordered ter-uni rapid equilibrium mechanism can be used to find the kinetic parameters of TPL. In an adequately stirred system, the apparent values of the kinetic parameters of whole cell TPL are equal whether the cells are free or encapsulated. The apparent K{sub M} of tyrosine varies with the amount of whole cells in the system, ranging from 0.2 to 0.3 mM. The apparent K{sub M} for phenol is 0.5 mM. The apparent K{sub M} values for pyruvate and ammonia are an order of magnitude greater for whole cells than they are for the cell free enzyme.

  2. Germination and persistence of Bacillus anthracis and Bacillus thuringiensis in soil microcosms.

    PubMed

    Bishop, A H

    2014-11-01

    Decontaminating large, outdoor spaces of Bacillus anthracis spores presents significant problems, particularly in soil. Proof was sought that the addition of germinant chemicals could cause spores of B. anthracis and Bacillus thuringiensis, a commonly used simulant of the threat agent, to convert to the less resistant vegetative form in a microcosm. Nonsterile plant/soil microcosms were inoculated with spores of B. thuringiensis and two nonpathogenic strains of B. anthracis. A combination of L-alanine (100 mmol l(-1)) and inosine (10 mmol l(-1)) resulted in a 6 log decrease in spore numbers in both strains of B. anthracis over 2 weeks at 22°C; a 3 log decrease in B. anthracis Sterne spore numbers was observed after incubation for 2 weeks at 10°C. Negligible germination nor a decrease in viable count occurred in either strain when the concentration of L-alanine was decreased to 5 mmol l(-1). Germinated spores of B. thuringiensis were able to persist in vegetative form in the microcosms, whereas those of B. anthracis rapidly disappeared. The pleiotropic regulator PlcR, which B. anthracis lacks, does not contribute to the persistence of B. thuringiensis in vegetative form in soil. The principle of adding germinants to soil to trigger the conversion of spores to vegetative form has been demonstrated. Bacillus anthracis failed to persist in vegetative form or resporulate in the microcosms after it had been induced to germinate. The large scale, outdoor decontamination of B. anthracis spores may be facilitated by the application of simple, defined combinations of germinants. © 2014 Crown Copyright. Journal of Applied Microbiology © 2014 Society for Applied Microbiology This article is Published with the permission of the Controller of HMSO and Queen's Printer for Scotland.

  3. Copolymer-grafted silica phase from a cation-anion monomer pair for enhanced separation in reversed-phase liquid chromatography.

    PubMed

    Mallik, Abul K; Qiu, Hongdeng; Takafuji, Makoto; Ihara, Hirotaka

    2014-05-01

    This work reports a new imidazolium and L-alanine derived copolymer-grafted silica stationary phase for ready separation of complex isomers using high-performance liquid chromatography (HPLC). For this purpose, 1-allyl-3-octadecylimidazolium bromide ([AyImC18]Br) and N-acryloyl-L-alanine sodium salt ([AAL]Na) ionic liquids (IL) monomers were synthesized. Subsequently, the bromide counteranion was exchanged with the 2-(acrylamido)propanoate organic counteranion by reacting the [AyImC18]Br with excess [AAL]Na in water. The obtained IL cation-anion monomer pair was then copolymerized on mercaptopropyl-modified silica (Sil-MPS) via a surface-initiated radical chain-transfer reaction. The selective retention behaviors of polycyclic aromatic hydrocarbons (PAHs), including some positional isomers, steroids, and nucleobases were investigated using the newly obtained Sil-poly(ImC18-AAL), and octadecyl silylated silica (ODS) was used as the reference column. Interesting results were obtained for the separation of PAHs, steroids, and nucleobases with the new organic phase. The results showed that the Sil-poly(ImC18-AAL) presented multiple noncovalent interactions, including hydrophobic, π-π, carbonyl-π, and ion-dipole interactions for the separation of PAHs and dipolar compounds. Only pure water was sufficient as the mobile phase for the separation of the nucleobases. Ten nucleosides and bases were separated, using only water as the mobile phase, within a very short time using the Sil-poly(ImC18-AAL), which is otherwise difficult to achieve using conventional hydrophobic columns such as ODS. The combination of electrostatic and hydrophobic interactions are important for the effective separation of such basic compounds without the use of any organic additive as the eluent on the Sil-poly(ImC18-AAL) column.

  4. l-Serine Deficiency Elicits Intracellular Accumulation of Cytotoxic Deoxysphingolipids and Lipid Body Formation*

    PubMed Central

    Esaki, Kayoko; Sayano, Tomoko; Sonoda, Chiaki; Akagi, Takumi; Suzuki, Takeshi; Ogawa, Takuya; Okamoto, Masahiro; Yoshikawa, Takeo; Hirabayashi, Yoshio; Furuya, Shigeki

    2015-01-01

    l-Serine is required to synthesize membrane lipids such as phosphatidylserine and sphingolipids. Nevertheless, it remains largely unknown how a diminished capacity to synthesize l-serine affects lipid homeostasis in cells and tissues. Here, we show that deprivation of external l-serine leads to the generation of 1-deoxysphingolipids (doxSLs), including 1-deoxysphinganine, in mouse embryonic fibroblasts (KO-MEFs) lacking d-3-phosphoglycerate dehydrogenase (Phgdh), which catalyzes the first step in the de novo synthesis of l-serine. A novel mass spectrometry-based lipidomic approach demonstrated that 1-deoxydihydroceramide was the most abundant species of doxSLs accumulated in l-serine-deprived KO-MEFs. Among normal sphingolipid species in KO-MEFs, levels of sphinganine, dihydroceramide, ceramide, and hexosylceramide were significantly reduced after deprivation of external l-serine, whereas those of sphingomyelin, sphingosine, and sphingosine 1-phosphate were retained. The synthesis of doxSLs was suppressed by supplementing the culture medium with l-serine but was potentiated by increasing the ratio of l-alanine to l-serine in the medium. Unlike with l-serine, depriving cells of external l-leucine did not promote the occurrence of doxSLs. Consistent with results obtained from KO-MEFs, brain-specific deletion of Phgdh in mice also resulted in accumulation of doxSLs in the brain. Furthermore, l-serine-deprived KO-MEFs exhibited increased formation of cytosolic lipid bodies containing doxSLs and other sphingolipids. These in vitro and in vivo studies indicate that doxSLs are generated in the presence of a high ratio of l-alanine to l-serine in cells and tissues lacking Phgdh, and de novo synthesis of l-serine is necessary to maintain normal sphingolipid homeostasis when the external supply of this amino acid is limited. PMID:25903138

  5. Defining Multiple Characteristic Raman Bands of α-Amino Acids as Biomarkers for Planetary Missions Using a Statistical Method

    NASA Astrophysics Data System (ADS)

    Rolfe, S. M.; Patel, M. R.; Gilmour, I.; Olsson-Francis, K.; Ringrose, T. J.

    2016-06-01

    Biomarker molecules, such as amino acids, are key to discovering whether life exists elsewhere in the Solar System. Raman spectroscopy, a technique capable of detecting biomarkers, will be on board future planetary missions including the ExoMars rover. Generally, the position of the strongest band in the spectra of amino acids is reported as the identifying band. However, for an unknown sample, it is desirable to define multiple characteristic bands for molecules to avoid any ambiguous identification. To date, there has been no definition of multiple characteristic bands for amino acids of interest to astrobiology. This study examined l-alanine, l-aspartic acid, l-cysteine, l-glutamine and glycine and defined several Raman bands per molecule for reference as characteristic identifiers. Per amino acid, 240 spectra were recorded and compared using established statistical tests including ANOVA. The number of characteristic bands defined were 10, 12, 12, 14 and 19 for l-alanine (strongest intensity band: 832 cm-1), l-aspartic acid (938 cm-1), l-cysteine (679 cm-1), l-glutamine (1090 cm-1) and glycine (875 cm-1), respectively. The intensity of bands differed by up to six times when several points on the crystal sample were rotated through 360 °; to reduce this effect when defining characteristic bands for other molecules, we find that spectra should be recorded at a statistically significant number of points per sample to remove the effect of sample rotation. It is crucial that sets of characteristic Raman bands are defined for biomarkers that are targets for future planetary missions to ensure a positive identification can be made.

  6. Atomic force microscopy study of germination and killing of Bacillus atrophaeus spores.

    PubMed

    Pinzón-Arango, Paola A; Scholl, Geoffrey; Nagarajan, Ramanathan; Mello, Charlene M; Camesano, Terri A

    2009-01-01

    Bacterial spores such as Bacillus atrophaeus are one of the most resistant life forms known and are extremely resistant to chemical and environmental factors in the dormant state. During germination, as bacterial spores progress towards the vegetative state, they become susceptible to anti-sporal agents. B. atrophaeus spores were exposed to the non-nutritive germinant dodecylamine (DDA), a cationic surfactant that can also be used as a killing agent, for up to 60 min, or to the nutrient germinant L-alanine. In kinetic studies, 99% of the spores were killed within 5 min of exposure to DDA. Atomic force microscopy (AFM) can be used as a sensitive tool to assess how the structure of the spore coat changes upon exposure to germinants or killing agents. Changes in cell height and roughness over time of exposure to DDA were examined using AFM. DDA caused the spore height to decrease by >50%, which may have been due to a partial breakdown of the spore coat. Treatment of B. atrophaeus with the nutrient germinant resulted in a decrease in height of spores after 2 h of incubation, from 0.7 +/- 0.1 microm to 0.3 +/- 0.2 microm. However, treatment with L-alanine did not change the surface roughness of the spores, indicating that the changes that occur during germination take place underneath the spore coat. We propose that exposure to DDA at high concentrations causes pores to form in the coat layer, killing B. atrophaeus without the need to fully germinate spores.

  7. Spore germination and germinant receptor genes in wild strains of Bacillus subtilis.

    PubMed

    Alzahrani, O M; Moir, A

    2014-09-01

    To compare the germination of laboratory and wild strains of Bacillus subtilis. The spore germination of B. subtilis 168 (subsp. subtilis) was compared with that of the laboratory strain W23 (subsp. spizizenii) and desert-sourced isolates, including one member of subsp. subtilis (RO-NN-1), strains TU-B-10, RO-E-2, N10 and DV1-B-1, (all subsp. spizizenii), the B. mojavensis strain RO-H-1 and a B. subtilis natto strain. All germinated in L-alanine, although some were slower, and some 10-fold less sensitive to germinant. All germinated in calcium dipicolinate (CaDPA). Germination in asparagine, glucose, fructose + KCl was slow and incomplete in many of the strains, and decoating RO-NN-1 and W23 spores did not restore germination rates. Comparing the sequences of B. subtilis strains 168, RO-NN-1, W23, TU-B-10 and DV1-B-1, the operons encoding GerA, B and K germinant receptors were intact, although the two additional operons yndDEF and yfkQRST had suffered deletions or were absent in several spizizenii strains. Wild strains possess an efficient germination machinery for L-alanine germination. AGFK germination is often less efficient, the gerB genes more diverged, and the two germinant receptor operons of unknown function have been lost from the genome in many subsp. spizizenii strains. The two major subspecies of B. subtilis have conserved GerA receptor function, confirming its importance, at least in the natural environments of these strains. © 2014 The Society for Applied Microbiology.

  8. Glycine restores the anabolic response to leucine in a mouse model of acute inflammation.

    PubMed

    Ham, Daniel J; Caldow, Marissa K; Chhen, Victoria; Chee, Annabel; Wang, Xuemin; Proud, Christopher G; Lynch, Gordon S; Koopman, René

    2016-06-01

    Amino acids, especially leucine, potently stimulate protein synthesis and reduce protein breakdown in healthy skeletal muscle and as a result have received considerable attention as potential treatments for muscle wasting. However, the normal anabolic response to amino acids is impaired during muscle-wasting conditions. Although the exact mechanisms of this anabolic resistance are unclear, inflammation and ROS are believed to play a central role. The nonessential amino acid glycine has anti-inflammatory and antioxidant properties and preserves muscle mass in calorie-restricted and tumor-bearing mice. We hypothesized that glycine would restore the normal muscle anabolic response to amino acids under inflammatory conditions. Relative rates of basal and leucine-stimulated protein synthesis were measured using SUnSET methodology 4 h after an injection of 1 mg/kg lipopolysaccharide (LPS). Whereas leucine failed to stimulate muscle protein synthesis in LPS-treated mice pretreated with l-alanine (isonitrogenous control), leucine robustly stimulated protein synthesis (+51%) in mice pretreated with 1 g/kg glycine. The improvement in leucine-stimulated protein synthesis was accompanied by a higher phosphorylation status of mTOR, S6, and 4E-BP1 compared with l-alanine-treated controls. Despite its known anti-inflammatory action in inflammatory cells, glycine did not alter the skeletal muscle inflammatory response to LPS in vivo or in vitro but markedly reduced DHE staining intensity, a marker of oxidative stress, in muscle cross-sections and attenuated LPS-induced wasting in C2C12 myotubes. Our observations in male C57BL/6 mice suggest that glycine may represent a promising nutritional intervention for the attenuation of skeletal muscle wasting. Copyright © 2016 the American Physiological Society.

  9. The two-component cell lysis genes holWMY and lysWMY of the Staphylococcus warneri M phage varphiWMY: cloning, sequencing, expression, and mutational analysis in Escherichia coli.

    PubMed

    Yokoi, Ken-Ji; Kawahigashi, Nobutaka; Uchida, Maiko; Sugahara, Kazuki; Shinohara, Masayuki; Kawasaki, Ken-Ichi; Nakamura, Shogo; Taketo, Akira; Kodaira, Ken-Ichi

    2005-05-23

    From the genome library of Staphylococcus warneri M, the two successive cell-lysis genes (holWMY and lytWMY) were cloned and characterized. The lytWMY gene encoded a protein (LysWMY), whose calculated molecular mass and pI were 54 kDa and 8.95, respectively. When overproduced in Escherichia coli, lysWMY directed a protein of 45 kDa (smaller than the predicted molecular mass), having N-terminal 13 residues identical with those predicted from DNA. Comparative analysis revealed that LysWMY significantly resembles the putative N-acetylmuramoyl-L-alanine amidases encoded by the staphylococcal phages phi11, 80 alpha, and Twort. Examination of modular organization of LysWMY identified three putative domains CHAP (for D-alanyl-glycyl endopeptidase), amidase (L-muramoyl-L-alanine amidase), and SH3 (cell wall recognition). Gene knockout analysis revealed that each of the two domains of CHAP and amidase was responsible for cell-lytic activity on a zymogram gel. Site-directed mutation of Cys29Ala, His92Ala, or Asn114Ala in the CHAP domain substantially reduced cell-lytic activity, suggesting that this Cys-His-Asn triad is crucial for the enzymatic function. On the other hand, the holWMY gene encoded a protein (HolWMY) with molecular mass and pI of 16 kDa and 4.36; this protein contained two potential transmembrane helices, resembling other predicted holins (a cytoplasmic membrane-disrupting protein) encoded by the S. aureus phage, phi11, 80 alpha, and Twort. Upon mitomycin C exposure of S. warneri M, a prophage (phiWMY) was induced and the virion was examined under electron microscopy. PCR amplification and sequencing revealed the presence of the holWMY-lysWMY genes in the phage genome.

  10. Insulin-releasing and insulin-like activity of Agaricus campestris (mushroom).

    PubMed

    Gray, A M; Flatt, P R

    1998-05-01

    Agaricus campestris (mushroom) has been documented as a traditional treatment for diabetes. Here the administration of mushroom in the diet (62.5 g/kg) and drinking water (2.5 g/l) countered the hyperglycaemia of streptozotocin-diabetic mice. An aqueous extract of mushroom (1 mg/ml) stimulated 2-deoxyglucose transport (2.0-fold), glucose oxidation (1.5-fold) and incorporation of glucose into glycogen (1.8-fold) in mouse abdominal muscle. In acute 20 min tests, 0.25-1 mg/ml aqueous extract of mushroom evoked a stepwise 3.5- to 4.6-fold stimulation of insulin secretion from the BRIN-BD11 pancreatic B-cell line. This effect was abolished by 0.5 mM diazoxide and prior exposure to extract did not affect subsequent stimulation of insulin secretion by 10 mM L-alanine, thereby negating a detrimental effect on cell viability. The effect of extract was potentiated by 16.7 mM glucose, L-alanine (10 mM) and IBMX (1 mM), and a depolarising concentration of KCl (25 mM) did not augment the insulin-releasing activity of mushroom. Activity of the extract was found to be heat stable, acetone soluble and unaltered by exposure to alkali, but decreased with exposure to acid. Dialysis to remove components with molecular mass < 2000 Da caused a 40% reduction in activity. Sequential extraction with solvents revealed insulin-releasing activity to be greatest in polar fractions. Lack of haemagglutinin activity with extract activity indicated that activity was unlikely to be due to a lectin-mediated event. These results demonstrate the presence of antihyperglycaemic, insulin-releasing and insulin-like activity in A. campestris.

  11. Solid-State NMR Study of Paramagnetic Bis(alaninato-κ(2)N,O)copper(II) and Bis(1-amino(cyclo)alkane-1-carboxylato-κ(2)N,O)copper(II) Complexes: Reflection of Stereoisomerism and Molecular Mobility in (13)C and (2)H Fast Magic Angle Spinning Spectra.

    PubMed

    Szalontai, Gábor; Csonka, Róbert; Speier, Gábor; Kaizer, József; Sabolović, Jasmina

    2015-05-18

    Solid-state stereochemistry and mobility of paramagnetic copper(II) complexes formed by aliphatic amino acids (l-alanine, d,l-alanine, 1-amino-2-methyl-alanine) and 1-amino(cyclo)alkane-1-carboxylic acids (alkane = propane, butane, pentane, hexane) as bidentate ligands has been studied by (13)C and (2)H solid-state fast magic angle spinning (MAS) NMR spectroscopy. We examined the prospective method to characterize solid-state paramagnetic compounds in a routine way. Both (13)C and (2)H MAS spectra can distinguish d,l and l,l diastereomers of natural and polydeuterated bis([Dn]alaninato)copper(II) (n = 0, 2, 8) complexes with axial and/or equatorial methyl positions (conformations) primarily due to different Fermi-contact (FC) contributions. The three-bond hyperfine couplings clearly show Karplus-like dependence on the torsional angles which turned out to be a useful assignment aid. Density functional theory calculations of the FC term and crystal structures were also used to aid the final assignments. The correlations obtained for bis(alaninato-κ(2)N,O)copper(II) complexes were successfully used to characterize other complexes. The usefulness of the (2)H MAS spectra of the deuterated complexes was underlined. Even the spectra of the easily exchangeable amine protons contained essential stereochemical information. In the case of a dimer structure of bis(1-aminohexane-1-carboxylato-κ(2)N,O)copper(II) both the (13)C and (2)H resolutions were good enough to confirm the presence of the cis and trans forms in the asymmetric unit. With regard to the internal solid-state motions in the crystal lattice, the obtained quadrupolar tensor parameters were similar for the d,l- and l,l-alaninato isomers and also for the cis-trans forms suggesting similar crystal packing effects, static amine deuterons involved in hydrogen bonding, and fast rotating methyl groups.

  12. Defining Multiple Characteristic Raman Bands of α-Amino Acids as Biomarkers for Planetary Missions Using a Statistical Method.

    PubMed

    Rolfe, S M; Patel, M R; Gilmour, I; Olsson-Francis, K; Ringrose, T J

    2016-06-01

    Biomarker molecules, such as amino acids, are key to discovering whether life exists elsewhere in the Solar System. Raman spectroscopy, a technique capable of detecting biomarkers, will be on board future planetary missions including the ExoMars rover. Generally, the position of the strongest band in the spectra of amino acids is reported as the identifying band. However, for an unknown sample, it is desirable to define multiple characteristic bands for molecules to avoid any ambiguous identification. To date, there has been no definition of multiple characteristic bands for amino acids of interest to astrobiology. This study examined L-alanine, L-aspartic acid, L-cysteine, L-glutamine and glycine and defined several Raman bands per molecule for reference as characteristic identifiers. Per amino acid, 240 spectra were recorded and compared using established statistical tests including ANOVA. The number of characteristic bands defined were 10, 12, 12, 14 and 19 for L-alanine (strongest intensity band: 832 cm(-1)), L-aspartic acid (938 cm(-1)), L-cysteine (679 cm(-1)), L-glutamine (1090 cm(-1)) and glycine (875 cm(-1)), respectively. The intensity of bands differed by up to six times when several points on the crystal sample were rotated through 360 °; to reduce this effect when defining characteristic bands for other molecules, we find that spectra should be recorded at a statistically significant number of points per sample to remove the effect of sample rotation. It is crucial that sets of characteristic Raman bands are defined for biomarkers that are targets for future planetary missions to ensure a positive identification can be made.

  13. The Metabolic Responses to L-Glutamine of Livers from Rats with Diabetes Types 1 and 2

    PubMed Central

    Comar, Jurandir Fernando; de Oliveira, Denise Silva; Bracht, Livia; Kemmelmeier, Fumie Suzuki; Peralta, Rosane Marina; Bracht, Adelar

    2016-01-01

    There are several claims about the beneficial effects of supplementing L-glutamine to both type 1 and type 2 diabetes. The purpose of the present study was to provide detailed knowledge about the fate of this amino acid in the liver, the first organ that receives the compound when ingested orally. The study was done using the isolated perfused rat liver, an experimental system that preserves the microcirculation of the organ and that allows to measured several parameters during steady-state and pre steady-state conditions. L-Glutamine was infused in the portal vein (5 mM) and several parameters were monitored. Livers from type 1 diabetic rats showed an accelerated response to L-glutamine infusion. In consequence of this accelerated response livers from type 1 diabetic rats presented higher rates of ammonia, urea, glucose and lactate output during the first 25–30 minutes following L-glutamine infusion. As steady-state conditions approached, however, the difference between type 1 diabetes and control livers tended to disappear. Measurement of the glycogen content over a period of 100 minutes revealed that, excepting the initial phase of the L-glutamine infusion, the increased glucose output in livers from type 1 diabetic rats was mainly due to accelerated glycogenolysis. Livers from type 2 diabetic rats behaved similarly to control livers with no accelerated glucose output but with increased L-alanine production. L-Alanine is important for the pancreatic β-cells and from this point of view the oral intake of L-glutamine can be regarded as beneficial. Furthermore, the lack of increased glucose output in livers from type 2 diabetic rats is consistent with observations that even daily L-glutamine doses of 30 g do not increase the glycemic levels in well controlled type 2 diabetes patients. PMID:27490892

  14. Inhibition of serine palmitoyltransferase in vitro and long-chain base biosynthesis in intact Chinese hamster ovary cells by. beta. -chloroalanine

    SciTech Connect

    Medlock, K.A.; Merrill, A.H. Jr.

    1988-09-06

    The effects of ..beta..-chloroalanine (..beta..-Cl-alanine) on the serine palmitoyltransferase activity and the de novo biosynthesis of sphinganine and sphingenine were investigated in vitro with rat liver microsomes and in vivo with intact Chinese hamster ovary (CHO) cells. The inhibition in vitro was rapid, irreversible, and concentration and time dependent and apparently involved the active site because inactivation only occurred with ..beta..-Cl-L-alanine and was blocked by L-serine. These are characteristics of mechanism-based (suicide) inhibition. Serine palmitoyltransferase (SPT) was also inhibited when intact CHO cells were incubated with ..beta..-Cl-alanine and this treatment inhibited (/sup 14/C)serine incorporation into long-chain bases by intact cells. The concentration dependence of the loss of SPT activity and of long-chain base synthesis was identical. The effects of ..beta..-Cl-alanine appeared to occur with little perturbation of other cell functions: the cells exhibited no loss in cell viability, (/sup 14/C)serine uptake was not blocked, total lipid biosynthesis from (/sup 14/C)acetic acid was not decreased (nor was the appearance of radiolabel in cholesterol and phosphatidylcholine), and (/sup 3/H)thymidine incorporation into DNA was not affected. There appeared to be little effect on protein synthesis based on the incorporation of (/sup 3/H)leucine, which was only decreased by 14%. Although ..beta..-Cl-L-alanine is known to inhibit other pyridoxal 5'-phosphate dependent enzymes, alanine and aspartate transaminases were not inhibited under these conditions. These results establish the close association between the activity of serine palmitoyltransferase and the cellular rate of long-chain base formation and indicate that ..beta..-Cl-alanine and other mechanism-based inhibitors might be useful to study alterations in cellular long-chain base synthesis.

  15. [Cardioprotective effects of glutamine in patients with ischemic heart disease operated under conditions of extracorporeal blood circulation].

    PubMed

    Lomivorotov, V V; Efremov, S M; Shmyrev, V A; Ponomarev, D N; Sviatchenko, A V; Kniaz'kova, L G

    2012-01-01

    It was conducted a study of glutamine cardioptotective effects during perioperative use in patients with ischemic heart disease, operated under CB. Exclusion criteria were: left ventricular ejection fraction less than 50%, diabetes melitus, myocardial infarction less than 3 months ago, Patients of the study group (n=25) had glutamine (20% solution N(2)-L-alanine-L-glutamine ("Dipeptiven" Fresenius Kabi, Germany); 0.4 g/kg/day. Patients of control group (n=25) received placebo (0.9% NaCl solution). The main indicators were the dynamics of troponin I, as well as central hemodynamics parameters. On the 1-st day after operation the concentration of troponin I was significantly lower in the glutamine-group compared placebo-group (1.280 (0.840-2.230) 2.410 (1.060-6.600) ng/ml; p=0.035). 4 hours after CB in a glutamine-group also had significantly large indicators of cardiac index (2.58 (2.34-2.91) l/min/m2 vs 2.03 (1.76-2.32)) l/min/m2; p=0,002) and stroke index (32.8 (27.8-36.0.) ml/m2 vs 26.1 (22.6-31.8) ml/m2; p=0.023). Systemic vascular resistance index was significantly lower in glutamine-group (1942 (1828-2209) dyn x s/cm(-5)/m2 vs 2456 (2400-3265) dyn x s/cm(-5)/m2; p=0.001). Conclusion. Perioperative use of N(2)-L-alanine-L-glutamine during the first 24 hours ofperioperative period gives cardioprotective effect in patients with ischemic heart disease operated under CB.

  16. Functional Analysis of All Aminotransferase Proteins Inferred from the Genome Sequence of Corynebacterium glutamicum

    PubMed Central

    Marienhagen, Jan; Kennerknecht, Nicole; Sahm, Hermann; Eggeling, Lothar

    2005-01-01

    Twenty putative aminotransferase (AT) proteins of Corynebacterium glutamicum, or rather pyridoxal-5′-phosphate (PLP)-dependent enzymes, were isolated and assayed among others with l-glutamate, l-aspartate, and l-alanine as amino donors and a number of 2-oxo-acids as amino acceptors. One outstanding AT identified is AlaT, which has a broad amino donor specificity utilizing (in the order of preference) l-glutamate > 2-aminobutyrate > l-aspartate with pyruvate as acceptor. Another AT is AvtA, which utilizes l-alanine to aminate 2-oxo-isovalerate, the l-valine precursor, and 2-oxo-butyrate. A second AT active with the l-valine precursor and that of the other two branched-chain amino acids, too, is IlvE, and both enzyme activities overlap partially in vivo, as demonstrated by the analysis of deletion mutants. Also identified was AroT, the aromatic AT, and this and IlvE were shown to have comparable activities with phenylpyruvate, thus demonstrating the relevance of both ATs for l-phenylalanine synthesis. We also assessed the activity of two PLP-containing cysteine desulfurases, supplying a persulfide intermediate. One of them is SufS, which assists in the sulfur transfer pathway for the Fe-S cluster assembly. Together with the identification of further ATs and the additional analysis of deletion mutants, this results in an overview of the ATs within an organism that may not have been achieved thus far. PMID:16267288

  17. Lab-in-a-syringe using gold nanoparticles for rapid colorimetric chiral discrimination of enantiomers.

    PubMed

    Zor, Erhan; Bekar, Nisa

    2017-05-15

    Nanomaterials with different characteristics are offering many ingenious sensing approaches with interest for simple and disposable paper-based (bio)sensing applications. In this study, the colorimetric discrimination of alanine enantiomers is examined and, more importantly, AuNPs-embedded paper-based lab-in-a-syringe (LIS) device is developed as a sensing strategy. The LIS consists of two cellulose acetate membranes: the conjugate pad capturing the analyte and the detection pad signaling the presence of the captured analyte, both are sandwiched between reusable plastic filter holders connected to a disposable syringe. The principle of LIS assay is based on the enantioselective interaction occurring between the inherently chiral AuNPs and enantiomers in the first filter holder, which results in aggregation of AuNPs to give a distinct colour change from red to purple in solution and finally the aggregated AuNPs is kept on the detection pad through vertical-flow operation. AuNPs show an enantioselective recognition response toward L-Alanine and limit of detection (LOD) value is determined as 0.77mM. In addition, we demonstrate the efficiency of the LIS device for detecting L-Alanine in human serum. The proposed LIS assay has some advantages such as useful for naked-eye observation, disposable, not time-consuming, inexpensive, no need of advanced instruments, easy to prepare and easy to handle. In the field, the approach which is the first demonstration of applicability of LIS device to show simple colorimetric enantioselective sensing of chiral species with a fast readout in less than 5min is truly new and may have broad interest in enantiosensing of various chiral molecules. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Effect of Na+ Concentration and Nutritional Factors on the Lag Phase and Exponential Growth Rates of the Marine Bacterium Deleya aesta and of Other Marine Species

    PubMed Central

    Berthelet, Marc; MacLeod, Robert A.

    1989-01-01

    Growth of the marine bacterium Deleya aesta in a succinate minimal medium showed increasingly long lag phases as Na+ was decreased below the optimum (200 to 500 mM). The minimum Na+ concentration permitting growth consistently was 15 mM. Supplementation of the medium with KHCO3 (as a source of CO2) or yeast extract, especially in combination, reduced the lag phase, increased the rate of exponential growth, and allowed growth at 8 mM Na+. KHCO3 did not reduce the lag period but did increase the rate of exponential growth of Deleya venusta, Deleya pacifica, and Alteromonas haloplanktis 214. Yeast extract was active for all three. The effect of yeast extract on D. aesta could be reproduced by a mixture of amino acids approximating its amino acid composition. l-Alanine, l-aspartate, and l-methionine, in combination, were the most effective in reducing the lag phase, although not as effective as the complete mixture. Succinate, l-aspartate, and l-alanine were transported into the cells by largely independent pathways and oxidized at rates which were much lower at 10 than at 200 mM Na+. l-Methionine was transported at a low rate in the absence of Na+ and at a higher rate at 10 mM but was not oxidized. Above 25 mM Na+, the rate of transport of the carbon source was not the rate-limiting step for growth. It is concluded that a combination of transportable carbon sources reduced the lag period and increased the rate of exponential growth because they can be taken up independently and at low Na+ utilized simultaneously. PMID:16347969

  19. Line-narrowing in proton-detected nitrogen-14 NMR.

    PubMed

    Cavadini, Simone; Vitzthum, Veronika; Ulzega, Simone; Abraham, Anuji; Bodenhausen, Geoffrey

    2010-01-01

    In solids spinning at the magic angle, the indirect detection of single-quantum (SQ) and double-quantum (DQ) (14)N spectra (I=1) via spy nuclei S=1/2 such as protons can be achieved in the manner of heteronuclear single- or multiple-quantum correlation (HSQC or HMQC) spectroscopy. The HMQC method relies on the excitation of two-spin coherences of the type T(11)(I)T(11)(S) and T(21)(I)T(11)(S) at the beginning of the evolution interval t(1). The spectra obtained by Fourier transformation from t(1) to omega(1) may be broadened by the homogenous decay of the transverse terms of the spy nuclei S. This broadening is mostly due to homonuclear dipolar S-S' interactions between the proton spy nuclei. In this work we have investigated the possibility of inserting rotor-synchronized symmetry-based C or R sequences and decoupling schemes such as Phase-Modulated Lee-Goldburg (PMLG) sequences in the evolution period. These schemes reduce the homonuclear proton-proton interactions and lead to an enhancement of the resolution of both SQ and DQ proton-detected (14)N HMQC spectra. In addition, we have investigated the combination of HSQC with symmetry-based sequences and PMLG and shown that the highest resolution in the (14)N dimension is achieved by using HSQC in combination with symmetry-based sequences of the R-type. We show improvements in resolution in samples of l-alanine and the tripeptide ala-ala-gly (AAG). In particular, for l-alanine the width of the (14)N SQ peak is reduced from 2 to 1.2 kHz, in agreement with simulations. We report accurate measurements of quadrupolar coupling constants and asymmetry parameters for amide (14)N in AAG peptide bonds.

  20. Role of amino acids as additives on sperm motility, plasma membrane integrity and lipid peroxidation levels at pre-freeze and post-thawed ram semen.

    PubMed

    Sangeeta, Sharon; Arangasamy, A; Kulkarni, S; Selvaraju, S

    2015-10-01

    The possibility of including amino acids for cryopreservation of ram semen to improve the quality of frozen semen was explored in this study in sheep model. 24 samples were collected in triplicate from 8 rams of 2-3 year old Bannur cross bred rams maintained at the Institute Experimental Livestock Unit. Semen was diluted in tris-egg yolk glycerol diluent and made into 7 aliquots as follows: aliquot 1 served as control, "l-alanine" was added at 100 and 135mM in the aliquots 2 and 3, "l-glutamine" was added at 20 and 25mM in the aliquots 4 and 5 and "l-proline" was added at 25 and 50mM in the aliquots 6 and 7, respectively. Diluted semen was filled in 0.25ml French straws and frozen in LN2. Inclusion of "l-proline" and "l-glutamine" in the diluent increased the percent live sperm (P<0.001), total motility (P<0.05) and maintained higher functional membrane and acrosomal integrity (P<0.001) by decreasing lipid peroxidation (P<0.001) compared to the control group. In contrast, "l-alanine" decreased the percentage of total motility, fast progressive spermatozoa and increased (P<0.01) the percentage of immotile spermatozoa. It can be concluded that 20mM "l-glutamine" and 25mM "l-proline" can be used as semen additive to freeze ram semen as they prevented cryoinjuries to sperm and improved the pre-freeze and post-thaw semen characteristics.