Sample records for n-tosyl-l-phenylalanine chloromethyl ketone

  1. Purification of a toxic metalloprotease produced by the pathogenic Photobacterium damselae subsp. piscicida isolated from cobia (Rachycentron canadum).

    PubMed

    Liu, Ping-Chung; Chuang, Wen-Hsiao; Lee, Kuo-Kau

    2011-01-01

    The aim of the present study was to purify and characterize a toxic protease secreted by the pathogenic Photobacterium damselae subsp. piscicida strain CP1 originally isolated from diseased cobia (Rachycentron canadum). The toxin isolated by anion exchange chromatography, was a metalloprotease, inhibited by L-cysteine, ethylenediaminetetraacetic acid (EDTA), ethylene glycol-bis(beta-aminoethyl ether)N,N,N',N'-tetraacetic acid (EGTA), 1,10-phenanthroline, N-tosyl-L-phenylalanine-chloromethyl ketone (TPCK), and N-alpha-p-tosyl-L-lysine-chloromethyl ketone (TLCK), and showed maximal activity at pH 6.0-8.0 and an apparent molecular mass of about 34.3 kDa. The toxin was also completely inhibited by HgCl2, and partially by sodium dodecyl sulfate (SDS) and CuCl2. The extracellular products and the partially purified protease were lethal to cobia with LD50 values of 1.26 and 6.8 microg protein/g body weight, respectively. The addition of EDTA completely inhibited the lethal toxicity of the purified protease, indicating that this metalloprotease was a lethal toxin produced by the bacterium.

  2. Activation of Bt Protoxin Cry1Ac in Resistant and Susceptible Cotton Bollworm.

    PubMed

    Wei, Jizhen; Liang, Gemei; Wang, Bingjie; Zhong, Feng; Chen, Lin; Khaing, Myint Myint; Zhang, Jie; Guo, Yuyuan; Wu, Kongming; Tabashnik, Bruce E

    2016-01-01

    Crystalline (Cry) proteins from Bacillus thuringiensis (Bt) are used extensively for insect control in sprays and transgenic plants, but their efficacy is reduced by evolution of resistance in pests. Here we evaluated reduced activation of Cry1Ac protoxin as a potential mechanism of resistance in the invasive pest Helicoverpa armigera. Based on the concentration killing 50% of larvae (LC50) for a laboratory-selected resistant strain (LF120) divided by the LC50 for its susceptible parent strain (LF), the resistance ratio was 1600 for Cry1Ac protoxin and 1200 for trypsin-activated Cry1Ac toxin. The high level of resistance to activated toxin as well as to protoxin indicates reduced activation of protoxin is not a major mechanism of resistance to Cry1Ac in LF120. For both insect strains, treatment with either the trypsin inhibitor N-a-tosyl-L-lysine chloromethyl ketone (TLCK) or the chymotrypsin inhibitor N-a-tosyl-L-phenylalanine chloromethyl ketone (TPCK) did not significantly affect the LC50 of Cry1Ac protoxin. Enzyme activity was higher for LF than LF120 for trypsin-like proteases, but did not differ between strains for chymotrypsin-like proteases. The results here are consistent with previous reports indicating that reduced activation of protoxin is generally not a major mechanism of resistance to Bt proteins.

  3. Activation of Bt Protoxin Cry1Ac in Resistant and Susceptible Cotton Bollworm

    PubMed Central

    Liang, Gemei; Wang, Bingjie; Zhong, Feng; Chen, Lin; Khaing, Myint Myint; Zhang, Jie; Guo, Yuyuan; Wu, Kongming; Tabashnik, Bruce E.

    2016-01-01

    Crystalline (Cry) proteins from Bacillus thuringiensis (Bt) are used extensively for insect control in sprays and transgenic plants, but their efficacy is reduced by evolution of resistance in pests. Here we evaluated reduced activation of Cry1Ac protoxin as a potential mechanism of resistance in the invasive pest Helicoverpa armigera. Based on the concentration killing 50% of larvae (LC50) for a laboratory-selected resistant strain (LF120) divided by the LC50 for its susceptible parent strain (LF), the resistance ratio was 1600 for Cry1Ac protoxin and 1200 for trypsin-activated Cry1Ac toxin. The high level of resistance to activated toxin as well as to protoxin indicates reduced activation of protoxin is not a major mechanism of resistance to Cry1Ac in LF120. For both insect strains, treatment with either the trypsin inhibitor N-a-tosyl-L-lysine chloromethyl ketone (TLCK) or the chymotrypsin inhibitor N-a-tosyl-L-phenylalanine chloromethyl ketone (TPCK) did not significantly affect the LC50 of Cry1Ac protoxin. Enzyme activity was higher for LF than LF120 for trypsin-like proteases, but did not differ between strains for chymotrypsin-like proteases. The results here are consistent with previous reports indicating that reduced activation of protoxin is generally not a major mechanism of resistance to Bt proteins. PMID:27257885

  4. Synthesis of EF24-tripeptide chloromethyl ketone: a novel curcumin-related anticancer drug delivery system.

    PubMed

    Sun, Aiming; Shoji, Mamoru; Lu, Yang J; Liotta, Dennis C; Snyder, James P

    2006-06-01

    The blood coagulation cascade includes a step in which the soluble protein, factor VIIa (fVIIa), complexes with its transmembrane receptor, tissue factor (TF). The fVIIa/TF protein-protein complex is subsequently drawn into the cell by endocytosis. The observation that TF is aberrantly and abundantly expressed on many cancer cells offers an opportunity to specifically target those cells with an effective anticancer drug. Thus, we propose a new drug delivery system, drug-linker-Phe-Phe-Arg-mk-fVIIa, which can associate with TF on the surface of cancer cells, but release the cytotoxic agent in the cytoplasm. Synthetic procedures have been developed for the preparation of phenylalanine-phenylalanine-arginine chloromethyl ketone, (FFRck) followed by coupling with the cytotoxin EF24 and subsequently fVIIa to give EF-24-FFRmk-fVIIa. When breast cancer cells (MDA-MB-231) and human melanoma cells (RPMI-7951) are treated with the complex, the cells are arrested to a greater extent than EF24 alone by comparison with controls.

  5. A chymotrypsin-like proteinase from the midgut of Tenebrio molitor larvae.

    PubMed

    Elpidina, E N; Tsybina, T A; Dunaevsky, Y E; Belozersky, M A; Zhuzhikov, D P; Oppert, B

    2005-08-01

    A chymotrypsin-like proteinase was isolated from the posterior midgut of larvae of the yellow mealworm, Tenebrio molitor, by ion-exchange and gel filtration chromatography. The enzyme, TmC1, was purified to homogeneity as determined by SDS-PAGE and postelectrophoretic activity detection. TmC1 had a molecular mass of 23.0 kDa, pI of 8.4, a pH optimum of 9.5, and the optimal temperature for activity was 51 degrees C. The proteinase displayed high stability at temperatures below 43 degrees C and in the pH range 6.5-11.2, which is inclusive of the pH of the posterior and middle midgut. The enzyme hydrolyzed long chymotrypsin peptide substrates SucAAPFpNA, SucAAPLpNA and GlpAALpNA and did not hydrolyze short chymotrypsin substrates. Kinetic parameters of the enzymatic reaction demonstrated that the best substrate was SucAAPFpNA, with k(cat app) 36.5 s(-1) and K(m) 1.59 mM. However, the enzyme had a lower K(m) for SucAAPLpNA, 0.5 mM. Phenylmethylsulfonyl fluoride (PMSF) was an effective inhibitor of TmC1, and the proteinase was not inhibited by either tosyl-l-phenylalanine chloromethyl ketone (TPCK) or N(alpha)-tosyl-l-lysine chloromethyl ketone (TLCK). However, the activity of TmC1 was reduced with sulfhydryl reagents. Several plant and insect proteinaceous proteinase inhibitors were active against the purified enzyme, the most effective being Kunitz soybean trypsin inhibitor (STI). The N-terminal sequence of the enzyme was IISGSAASKGQFPWQ, which was up to 67% similar to other insect chymotrypsin-like proteinases and 47% similar to mammalian chymotrypsin A. The amino acid composition of TmC1 differed significantly from previously isolated T. molitor enzymes.

  6. Surface modification of hydroxyapatite nanoparticles by poly( L-phenylalanine) via ROP of L-phenylalanine N-carboxyanhydride (Pha-NCA)

    NASA Astrophysics Data System (ADS)

    Dai, Yanfeng; Xu, Min; Wei, Junchao; Zhang, Haobin; Chen, Yiwang

    2012-01-01

    The surface of hydroxyapatite nanoparticles was modified by poly(L-phenylalanine) via the ring opening polymerization (ROP) of L-phenylalanine N-carboxyanhydride. The preparation procedure was monitored by Fourier transform infrared spectroscopy (FTIR), and the modified hydroxyapatite was characterized by thermal gravimetric analysis (TGA) and X-ray diffraction (XRD). The results showed that the surface grafting amounts of poly(L-phenylalanine) on HA ranging from 20.26% to 38.92% can be achieved by tuning the reaction condition. The XRD patterns demonstrated that the crystalline structure of the modified hydroxyapatite was nearly the same with that of HA, implying that the ROP was an efficient surface modification method. The MTT assay proved that the biocompatibility of modified HA was very good, which showed the potential application of modified HA in bone tissue engineering.

  7. Chiral discrimination in cyclodextrin complexes of amino acid derivatives: beta-cyclodextrin/N-acetyl-L-phenylalanine and N-acetyl-D-phenylalanine complexes.

    PubMed

    Alexander, Jennifer M; Clark, Joanna L; Brett, Tom J; Stezowski, John J

    2002-04-16

    In a systematic study of molecular recognition of amino acid derivatives in solid-state beta-cyclodextrin (beta-CD) complexes, we have determined crystal structures for complexes of beta-cyclodextrin/N-acetyl-L-phenylalanine at 298 and 20 K and for N-acetyl-D-phenylalanine at 298 K. The crystal structures for the N-acetyl-L-phenylalanine complex present disordered inclusion complexes for which the distribution of guest molecules at room temperature is not resolvable; however, they can be located with considerable confidence at low temperature. In contrast, the complex with N-acetyl-D-phenylalanine is well ordered at room temperature. The latter complex presents an example of a complex in this series in which a water molecule is included deeply in the hydrophobic torus of the extended dimer host. In an effort to understand the mechanisms of molecular recognition giving rise to the dramatic differences in crystallographic order in these crystal structures, we have examined the intermolecular interactions in detail and have examined insertion of the enantiomer of the D-complex into the chiral beta-CD complex crystal lattice.

  8. N-(L-2-aminopentanoyl)-L-phenylalanine dihydrate, a hydrophobic dipeptide with a nonproteinogenic residue.

    PubMed

    Görbitz, Carl Henrik; Yadav, Vitthal N

    2013-09-01

    The title dipeptide, better known as L-norvalyl-L-phenylalanine {systematic name: (S)-2-[(S)-2-aminopentanamido]-3-phenylpropanoic acid dihydrate}, C14H20N2O3·2H2O, has a nonproteinogenic N-terminal residue. In the solid state, it takes on a molecular conformation typical for one of the three classes of nanoporous dipeptides, but like two related compounds with a hydrophobic N-terminal residue and a C-terminal L-phenylalanine, it fails to form channels or pores. Instead, the crystal structure is divided into distinct hydrophobic and hydrophilic layers, the latter encompassing cocrystallized water molecules connecting the charged N- and C-terminal groups.

  9. Two types of death of poliovirus-infected cells: caspase involvement in the apoptosis but not cytopathic effect.

    PubMed

    Agol, V I; Belov, G A; Bienz, K; Egger, D; Kolesnikova, M S; Raikhlin, N T; Romanova, L I; Smirnova, E A; Tolskaya, E A

    1998-12-20

    The death of poliovirus-infected cells may occur in two forms: canonical cytopathic effect (CPE) (on productive infections) or apoptosis (when the viral reproduction is hindered by certain drugs or some other restrictive conditions). Morphological manifestations of the CPE and apoptosis, being distinct, share some traits (e.g., chromatin condensation and nuclear deformation). It was shown here that a permeable caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp-(OMe) fluoromethyl ketone (zVAD.fmk), prevented the development of the poliovirus-induced apoptosis on abortive infection. The apoptotic pathway could be dissected by an inhibitor of chymotrypsin-like serine proteases, N-tosyl-l-phenylalanine chloromethyl ketone (TPCK), which prevented the cleavage of DNA to oligonucleosome-sized pieces and nuclear fragmentation but did not suppress cellular shrinkage, cytoplasmic blebbing, and partial chromatin condensation. These results demonstrate that caspase activation is involved in the execution phase of the viral apoptosis and suggest that a nuclear subset of the apoptotic program is under a separate control, involving a TPCK-sensitive event. Neither zVAD.fmk nor TPCK, at the concentrations affecting the apoptotic response, exerted appreciable influence on the virus growth or cellular pathological changes on productive infection, indicating that the pathways leading to the poliovirus-evoked CPE and apoptosis are different. Copyright 1998 Academic Press.

  10. Purification and characterization of chymotrypsin from viscera of vermiculated sailfin catfish, Pterygoplichthys disjunctivus, Weber, 1991.

    PubMed

    Villalba-Villalba, Ana Gloria; Ramírez-Suárez, Juan Carlos; Pacheco-Aguilar, Ramón; Valenzuela-Soto, Elisa Miriam; Lugo-Sánchez, María Elena; Figueroa-Soto, Ciria Guadalupe

    2013-04-01

    Pterygoplichthys disjunctivus viscera chymotrypsin was purified by fractionation with ammonium sulfate (30-70 % saturation), gel filtration, affinity, and ion exchange chromatography. Chymotrypsin molecular weight was approximately 29 kDa according to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), shown a single band in zymogram. Electrofocusing study suggested being an anionic enzyme (pI ≈ 3.9), exhibiting maximal activity at pH 9 and 50 °C, using Suc-Ala-Ala-Pro-Phe-p-nitroanilide (SAAPNA) as substrate. Enzyme was effectively inhibited by phenyl methyl sulfonyl fluoride (PMSF) (99 %), and N-tosyl-L-phenylalanine chloromethyl ketone (TPCK) (94 %). Enzyme activity was affected by the following ions in decreasing order: Hg(2+), Fe(2+), Cu(2+), Li(1+), Mg(2+), K(1+), Mn(2+), while Ca(2+) had no effect. Chymotrypsin activity decreased continuously as NaCl concentration increased (from 0 to 30 %). K m and V max values were 0.72 ± 1.4 mM and 1.15 ± 0.06 μmol/min/mg of protein, respectively (SAAPNA as substrate). Results suggest the enzyme has a potential application where low processing temperatures are needed, such as in fish sauce production.

  11. Regulation of L-phenylalanine ammonia-lyase by L-phenylalanine and nitrogen in Neurospora crassa.

    PubMed Central

    Sikora, L A; Marzluf, G A

    1982-01-01

    Neurospora crassa possesses an inducible L-phenylalanine ammonia-lyase that is expressed only when cells are derepressed for nitrogen in the presence of L-phenylalanine. Enzyme synthesis requires both induction by L-phenylalanine and simultaneous nitrogen catabolite derepression. Carbon limitation in the presence of phenylalanine does not elicit induction of L-phenylalanine ammonia-lyase. Specific induction by L-phenylalanine is required, and other amino acids completely failed to induce any lyase activity. The nit-2 gene is a major regulatory locus which is believed to mediate nitrogen catabolite repression in Neurospora. Mutants of nit-2 fail to express any phenylalanine ammonia-lyase activity under conditions of derepression and induction which lead to good enzyme induction in the wild type and in nit-2 revertants. The loss of lyase activity in nit-2 mutants does not result from inducer exclusion, which suggests that the nit-2 gene product has a direct role in controlling the expression of this enzyme. Substantial amounts of the enzyme were detected in the growth medium as well as in cell extracts. Inhibitors of protein synthesis or RNA synthesis block the induction of L-phenylalanine ammonia-lyase, suggesting that expression of this enzyme is controlled at the level of transcription. PMID:6210688

  12. Studies on activity, distribution, and zymogram of protease, α-amylase, and lipase in the paddlefish Polyodon spathula.

    PubMed

    Ji, H; Sun, H T; Xiong, D M

    2012-06-01

    A series of biochemical determination and electrophoretic observations have been conducted to analyze the activities and characteristics of protease, α-amylase, and lipase of paddlefish Polyodon spathula. The results obtained have been compared with those of bighead carp (Aristichthys nobilis) and hybrid sturgeon (Huso dauricus ♀ × Acipenser schrenki Brandt ♂), in order to increase available knowledge of the physiological characteristics of this sturgeon species and to gain information with regard to its nutrition. Further, a comparative study of enzymatic activity, distribution, and characterization between commercial feed-reared paddlefish (CG) and natural live food-reared (NG) paddlefish was conducted. Results showed that higher proteolytic activity was observed in the pH range 2.5-3.0 and at a pH of 7.0 for paddlefish. Levels of acid protease activity of paddlefish were similar to that of hybrid sturgeon, and significantly higher than that of bighead carp. The inhibition assay of paddlefish showed that the rate of inhibition of tosyl-phenylalanine chloromethyl ketone was approximately 2.6-fold that of tosyl-lysine chloromethyl ketone. There was no significant difference observed for acid protease activity between PG and CG groups, whereas the activity of alkaline protease, α-amylase, and lipase in the PG group were significantly lower than those in the CG group. The substrate sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis further showed that there were certain types of enzymes, especially α-amylase, with similar molecular mass in the paddlefish and hybrid sturgeon. It can be inferred that acid digestion was main mechanism for protein hydrolysis in paddlefish, as reported for other fishes with a stomach. This indicates that the paddlefish requires higher alkaline protease, α-amylase, and lipase activity to digest natural live food.

  13. Therapeutic implication of L-phenylalanine aggregation mechanism and its modulation by D-phenylalanine in phenylketonuria.

    PubMed

    Singh, Virender; Rai, Ratan Kumar; Arora, Ashish; Sinha, Neeraj; Thakur, Ashwani Kumar

    2014-01-27

    Self-assembly of phenylalanine is linked to amyloid formation toxicity in phenylketonuria disease. We are demonstrating that L-phenylalanine self-assembles to amyloid fibrils at varying experimental conditions and transforms to a gel state at saturated concentration. Biophysical methods including nuclear magnetic resonance, resistance by alpha-phenylglycine to fibril formation and preference of protected phenylalanine to self-assemble show that this behaviour of L-phenylalanine is governed mainly by hydrophobic interactions. Interestingly, D-phenylalanine arrests the fibre formation by L-phenylalanine and gives rise to flakes. These flakes do not propagate further and prevent fibre formation by L-phenylalanine. This suggests the use of D-phenylalanine as modulator of L-phenylalanine amyloid formation and may qualify as a therapeutic molecule in phenylketonuria.

  14. Therapeutic implication of L-phenylalanine aggregation mechanism and its modulation by D-phenylalanine in phenylketonuria

    PubMed Central

    Singh, Virender; Rai, Ratan Kumar; Arora, Ashish; Sinha, Neeraj; Thakur, Ashwani Kumar

    2014-01-01

    Self-assembly of phenylalanine is linked to amyloid formation toxicity in phenylketonuria disease. We are demonstrating that L-phenylalanine self-assembles to amyloid fibrils at varying experimental conditions and transforms to a gel state at saturated concentration. Biophysical methods including nuclear magnetic resonance, resistance by alpha-phenylglycine to fibril formation and preference of protected phenylalanine to self-assemble show that this behaviour of L-phenylalanine is governed mainly by hydrophobic interactions. Interestingly, D-phenylalanine arrests the fibre formation by L-phenylalanine and gives rise to flakes. These flakes do not propagate further and prevent fibre formation by L-phenylalanine. This suggests the use of D-phenylalanine as modulator of L-phenylalanine amyloid formation and may qualify as a therapeutic molecule in phenylketonuria. PMID:24464217

  15. Synthesis and analysis of 2-[211At]-L-phenylalanine and 4-[211At]-L-phenylalanine and their uptake in human glioma cell cultures in-vitro.

    PubMed

    Meyer, Geerd J; Walte, Almut; Sriyapureddy, Siva R; Grote, Michaela; Krull, Doris; Korkmaz, Zekiye; Knapp, Wolfram H

    2010-06-01

    2-[211At]-L-phenylalanine and 4-[211At]-L-phenylalanine were prepared from the corresponding iodo and bromo derivatives using the Cu(+)-assisted nucleophilic exchange. 4-[211At]-L-phenylalanine was additionally prepared by destannylation of the BOC-derivatized 4-tributylstannyl-L-phenylalanine. Radiochemical yields of 2-[211At]-L-phenylalanine and 4-[211At]-L-phenylalanine by nucleophilic exchange were 52-74% and 65-85%. Radiochemical yield of 4-[211At]-L-phenylalanine by electrophilic destannylation was 35-50%. HPLC sequence analysis showed that 2-[211At]-L-phenylalanine followed the halogen sequence (FL-phenylalanine eluted between 4-Br-L-phenylalanine and 4-I-L-phenylalanine (FL-phenylalanine and 4-[131I]-L-phenylalanine in DBTRG-05MG glioma cells was inhibited by l-phenylalanine 7-fold and 6-fold, respectively. Copyright 2010 Elsevier Ltd. All rights reserved.

  16. Stereospecificity of phenylalanine plasma kinetics and hydroxylation in man following oral application of a stable isotope-labelled pseudo-racemic mixture of L- and D-phenylalanine.

    PubMed

    Lehmann, W D; Theobald, N; Fischer, R; Heinrich, H C

    1983-03-14

    L-[15N]Phenylalanine and D-[2H5]phenylalanine have been administered orally to two healthy adult volunteers as a pseudo-racemic mixture at a dose of 25 mg/kg each. After oral application, the plasma kinetics of phenylalanine and tyrosine have been followed by the combined use of high pressure liquid chromatography and field desorption mass spectrometry. Additional incubation with D-amino acid oxidase was used to determine the enantiomeric composition of the differently labelled species of phenylalanine and tyrosine. D-Phenylalanine plasma levels show a faster rise to higher maximum values compared to L-phenylalanine (D/L ratio at maximum 3.19, 3.26). L-Phenylalanine is efficiently hydroxylated to L-tyrosine. In contrast, conversion of D-phenylalanine to the L-form with subsequent hydroxylation to L-tyrosine was observed. From the plasma kinetics it is estimated that about 1/3 of the applied dose of 25 mg/kg of D-phenylalanine is converted to the L-isomer. Of the administered dose of L-phenylalanine only very small amounts are excreted into urine as such (0.25%, 0.8%), whereas a substantial amount of the D-phenylalanine dose is found in urine (27.4%, 38.0%).

  17. Amino Acid Isomerization in the Production of l-Phenylalanine from d-Phenylalanine by Bacteria1

    PubMed Central

    Chibata, Ichiro; Tosa, Tetsuya; Sano, Ryujiro

    1965-01-01

    To establish an advantageous method for the production of l-amino acids, microbial isomerization of d- and dl-amino acids to l-amino acids was studied. Screening experiments on a number of microorganisms showed that cell suspensions of Pseudomonas fluorescens and P. miyamizu were capable of isomerizing d- and dl-phenylalanines to l-phenylalanine. Various conditions suitable for isomerization by these organisms were investigated. Cells grown in a medium containing d-phenylalanine showed highest isomerization activity, and almost completely converted d- or dl-phenylalanine into l-phenylalanine within 24 to 48 hr of incubation. Enzymatic studies on this isomerizing system suggested that the isomerization of d- or dl-phenylalanine is not catalyzed by a single enzyme, “amino acid isomerase,” but the conversion proceeds by a two step system as follows: d-pheylalanine is oxidized to phenylpyruvic acid by d-amino acid oxidase, and the acid is converted to l-phenylalanine by transamination or reductive amination. PMID:14339270

  18. Regulation of L-phenylalanine ammonia-lyase from Rhizoctonia solani.

    PubMed Central

    Kalghatgi, K K; Subba Rao, P V

    1976-01-01

    Maximal levels of L-henylalanine ammonia-lyase activity were observed when the mycelial felts of Rhizoctonia solani were grown for 4.5 days on Byrde synthetic medium containing 3.5% glucose and 0.3% L-phenylalanine, Differential centrifugation studies have indicated that the enzyme is localized in the soluble fraction. The time course of induction of L-phenylalanine ammonia-lyase activity by L-phenylalanine showed a lag period of 1 to 1.5 h and reached a maximum around 4 to 6 h after the addition of the inducer to the medium. L-Phenylalanine, L-tyrosine, and L-tryptophan were nearly equally efficient inducers of the enzyme. D-Phenylalanine was as efficient as the L-isomer, whereas D-tyrosine was a poor inducer. Light, gibberellic acid, indole 3-acetic acid, and kinetin had no effect on the induction of L-phenylalanine ammonia-lyase activity. Cycloheximide did not inhibit the uptake of amino acids by the mycelia but completely blocked the incorporation of radioactive amino acids into soluble proteins and the development of L-phenylalanine ammonia-lyase activity. Actinomycin D inhibited both the incorporation of 32P into ribonucleic acid and the enzyme activity. Conclusive evidence for de novo synthesis of L-phenylalanine ammonia-lyase was obtained by the incorporation of radioactive amino acids into the enzyme. Electrophoretic analysis of the purified preparation showed a single protein band that coincided with radioactivity and L-phenylalanine ammonia-lyase activity. Glucose and intermediates of the tricarboxylic acid cycle, like citric acid, alpha-ketoglutaric acid, and succinic acid, and the metabolites of L-phenylalanine, like o-coumaric acid, o-hydroxyphenylacetic acid, and protocatechuic acid, significantly repressed L-phenylalanine ammonia-lyase activity. The observed repression was not relieved by cyclic adenosine 5'-triphosphate. Images PMID:1262311

  19. Hydrogen bonding pattern in N-benzoyl(- DL-)- L-phenylalanines as revealed by solid-state NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Potrzebowski, M. J.; Schneider, C.; Tekely, P.

    1999-11-01

    The nature of the hydrogen bonding pattern has been investigated in N-benzoyl- DL-phenylalanine ( 1) and N-benzoyl- L-phenylalanine ( 2) polymorphes by solid-state NMR spectroscopy. It has been shown that the multiple resonances of carboxyl carbon in 2 are directly connected to different types of hydrogen bonding. The differences in intermolecular distances of carboxyl groups involved in different types of hydrogen bonding have been visualized by the 2D exchange and 1D ODESSA experiments. Potential applications of such a new approach include the exploration of intermolecular distances in hydrogen bonded compounds with singly labeled biomolecules.

  20. Highly Enantioselective Three-Component Direct Mannich Reactions of Unfunctionalized Ketones Catalyzed by Bifunctional Organocatalysts

    PubMed Central

    Guo, Qunsheng; Zhao, John Cong-Gui

    2013-01-01

    A highly stereoselective three-component direct Mannich reaction between aromatic aldehydes, p-toluenesulfonamide, and unfunctionalized ketones was achieved through an enolate mechanism for the first time with a bifunctional quinidine thiourea catalyst. The corresponding N-tosylated β-aminoketones were obtained in high yields and excellent diastereo- and enantioselectivities (up to >99:1 dr and >99% ee). PMID:23343472

  1. Preparation of l-phenylalanine-imprinted solid-phase extraction sorbent by Pickering emulsion polymerization and the selective enrichment of l-phenylalanine from human urine.

    PubMed

    Li, Ji; Hu, Xiaoling; Guan, Ping; Zhang, Xiaoyan; Qian, Liwei; Zhang, Nan; Du, Chunbao; Song, Renyuan

    2016-05-01

    A novel l-phenylalanine molecularly imprinted solid-phase extraction sorbent was synthesized by the combination of Pickering emulsion polymerization and ion-pair dummy template imprinting. Compared to other polymerization methods, the molecularly imprinted polymers thus prepared exhibit a high specific surface, large pore diameter, and appropriate particle size. The key parameters for solid-phase extraction were optimized, and the result indicated that the molecularly imprinted polymer thus prepared exhibits a good recovery of 98.9% for l-phenylalanine. Under the optimized conditions of the procedure, an analytical method for l-phenylalanine was well established. By comparing the performance of the molecularly imprinted polymer and a commercial reverse-phase silica gel, the obtained molecularly imprinted polymer as an solid-phase extraction sorbent is more suitable, exhibiting high precision (relative standard deviation 3.2%, n = 4) and a low limit of detection (60.0 ± 1.9 nmol·L(-1) ) for the isolation of l-phenylalanine. Based on these results, the combination of the Pickering emulsion polymerization and ion-pair dummy template imprinting is effective for preparing selective solid-phase extraction sorbents for the separation of amino acids and organic acids from complex biological samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Synthesis and Explosion Hazards of 4-Azido-l-phenylalanine.

    PubMed

    Richardson, Mark B; Brown, Derek B; Vasquez, Carlos A; Ziller, Joseph W; Johnston, Kevin M; Weiss, Gregory A

    2018-04-20

    A reliable, scalable, cost-effective, and chromatography-free synthesis of 4-azido-l-phenylalanine beginning from l-phenylalanine is described. Investigations into the safety of the synthesis reveal that the Ullman-like Cu(I)-catalyzed azidation step does not represent a significant risk. The isolated 4-azido-l-phenylalanine product, however, exhibits previously undocumented explosive characteristics.

  3. Synthesis and properties of poly(L-lactide)-b-poly (L-phenylalanine) hybrid copolymers.

    PubMed

    Planellas, Marc; Puiggalí, Jordi

    2014-07-29

    Hybrid materials constituted by peptides and synthetic polymers have nowadays a great interest since they can combine the properties and functions of each constitutive block, being also possible to modify the final characteristics by using different topologies. Poly(l-lactide-b-l-phenylalanine) copolymers with various block lengths were synthesized by sequential ring-opening polymerization of l-lactide and the N-carboxyanhydride of l-phenylalanine. The resulting block copolymers were characterized by NMR spectrometry, IR spectroscopy, gel permeation chromatography, MALDI-TOF and UV-vis, revealing the successful incorporation of the polyphenylalanine (PPhe) peptide into the previously formed poly(l-lactide) (PLLA) polymer chain. X-ray diffraction and DSC data also suggested that the copolymers were phase-separated in domains containing either crystalline PLLA or PPhe phases. A peculiar thermal behavior was also found by thermogravimetric analysis when polyphenylalanine blocks were incorporated into polylactide.

  4. Induction of L-phenylalanine ammonia-lyase during utilization of phenylalanine as a carbon or nitrogen source in Rhodotorula glutinis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Marusich, W.C.; Jensen, R.A.; Zamir, L.O.

    Rhodotorula glutinis is a convenient source of L-phenylalanine ammonia-lyase, an enzyme that is useful as a biochemical reagent in the assay of L-phenylalanine. There have been previous descriptions of induced lyase production in complex medium where induction occurs late in exponential growth, suggesting a role in secondary metabolism such as is the case in higher plants. A higher specific activity of L-phenylalanine ammonia-lyase (sixfold higher than in complex medium) can be obtained during midexponential growth in a defined medium containing L-phenylalanine as the sole source of carbon. L-phenylalanine will also induce lyase synthesis during exponential growth in minimal medium inmore » which L-phenylalanine is the sole source of nitrogen. The appearance of lyase in complex medium supplemented with L-phenylalanine is probably triggered fortuitously by exhaustion late in growth of a prime source of nitrogen. In this study, R. glutinis appeared to express a single lyase enzyme, regardless of whether induction was nitrogen signaled or carbon signaled. Thin-layer chromatographic analysis of ether extracts prepared fom cultures induced with doubly labeled (U-/sup 14/C; ring-4-/sup 3/H) L-phenylalanine provided evidence of a catabolic sequence containing cinnamic acid, benzoic acid, and 4-hydroxybenzoic acid as degradative intermediates. 3,4-Dihydroxybenzoic acid was not identified as a catabolic intermediate.« less

  5. Induction of L-phenylalanine ammonia-lyase during utilization of phenylalanine as a carbon or nitrogen source in Rhodotorula glutinis.

    PubMed Central

    Marusich, W C; Jensen, R A; Zamir, L O

    1981-01-01

    Rhodotorula glutinis is a convenient source of L-phenylalanine ammonia-lyase, an enzyme that is useful as a biochemical reagent in the assay of L-phenylalanine. There have been previous descriptions of induced lyase production in complex medium where induction occurs late in exponential growth, suggesting a role in secondary metabolism such as is the case in higher plants. A higher specific activity of L-phenylalanine ammonia-lyase (sixfold higher than a complex medium) can be obtained during midexponential growth in a defined medium containing L-phenylalanine as the sole source of carbon. L-Phenylalanine will also induce lyase synthesis during exponential growth in minimal in which L-phenylalanine is the sole source of nitrogen. The appearance of lyase in complex medium supplemented with L-phenylalanine is probably triggered fortuitously by exhaustion late in growth of a prime source of nitrogen. In this study, R. glutinis appeared to express a single lyase enzyme, regardless of whether induction was nitrogen signaled or carbon signaled. Thin-layer chromatographic analysis of ether extracts prepared from cultures induced with doubly labeled (U-14C; ring-4-3H) L-phenylalanine provided evidence of a catabolic sequence containing cinnamic acid, benzoic acid, and 4-hydroxybenzoic acid as degradative intermediates. 3,4-Dihydroxybenzoic acid was not identified as a catabolic intermediate. PMID:7195398

  6. Reduction of L-phenylalanine in protein hydrolysates using L-phenylalanine ammonia-lyase from Rhodosporidium toruloides.

    PubMed

    Castañeda, María Teresita; Adachi, Osao; Hours, Roque Alberto

    2015-10-01

    L-Phenylalanine ammonia-lyase (PAL, EC 4.3.1.25) from Rhodosporidium toruloides was utilized to remove L-phenylalanine (L-Phe) from different commercial protein hydrolysates. A casein acid hydrolysate (CAH, L-Phe ~2.28 %) was employed as a model substrate. t-Cinnamic acid resulting from deamination of L-Phe was extracted, analyzed at λ = 290 nm, and used for PAL activity determination. Optimum reaction conditions, optimized using successive Doehlert design, were 35 mg mL(-1) of CAH and 800 mU mL(-1) of PAL, while temperature and pH were 42 °C and 8.7, respectively. Reaction kinetics of PAL with CAH was determined under optimized conditions. Then, removal of L-Phe from CAH was tested. Results showed that more than 92 % of initial L-Phe was eliminated. Similar results were obtained with other protein hydrolysates. These findings demonstrate that PAL is a useful biocatalyst for L-Phe removal from protein hydrolysates, which can be evaluated as potential ingredients in foodstuffs for PKU patients.

  7. A new approach for quantitative analysis of L-phenylalanine using a novel semi-sandwich immunometric assay.

    PubMed

    Kubota, Kazuyuki; Mizukoshi, Toshimi; Miyano, Hiroshi

    2013-10-01

    Here, we describe a novel method for L-phenylalanine analysis using a sandwich-type immunometric assay approach for use as a new method for amino acid analysis. To overcome difficulties of the preparation of high-affinity and selectivity monoclonal antibodies against L-phenylalanine and the inability to use sandwich-type immunometric assays due to their small molecular weight, three procedures were examined. First, amino groups of L-phenylalanine were modified by "N-Fmoc-L-cysteine" (FC) residues and the derivative (FC-Phe) was used as a hapten. Immunization of mice with bovine serum albumin/FC-Phe conjugate successfully yielded specific monoclonal anti-FC-Phe antibodies. Second, a new derivatization reagent, "biotin linker conjugate of FC-Phe N-succinimidyl ester" (FC(Biotin)-NHS), was synthesized to convert L-phenylalanine to FC-(Biotin)-Phe as a hapten structure. The biotin moiety linked to the thiol group of cysteine formed a second binding site for streptavidin/horseradish peroxidase (HRP) conjugates for optical detection. Third, a new semi-sandwich-type immunometric assay was established using pre-derivatized L-phenylalanine, the monoclonal anti-FC-Phe antibody, and streptavidin/HRP conjugate (without second antibody). Using the new "semi-sandwich" immunometric assay system, a detection limit of 35 nM (60 amol per analysis) and a detection range of 0.1-20 μM were attained using a standard L-phenylalanine solution. Rat plasma samples were analyzed to test reliability. Intra-day assay precision was within 6% of the coefficient of variation; inter-day variation was 0.1%. The recovery rates were from 92.4 to 123.7%. This is the first report of the quantitative determination of L-phenylalanine using a reliable semi-sandwich immunometric assay approach and will be applicable to the quantitative determination of other amino acids.

  8. Synthesis and Properties of Poly(l-lactide)-b-poly (l-phenylalanine) Hybrid Copolymers

    PubMed Central

    Planellas, Marc; Puiggalí, Jordi

    2014-01-01

    Hybrid materials constituted by peptides and synthetic polymers have nowadays a great interest since they can combine the properties and functions of each constitutive block, being also possible to modify the final characteristics by using different topologies. Poly(l-lactide-b-l-phenylalanine) copolymers with various block lengths were synthesized by sequential ring-opening polymerization of l-lactide and the N-carboxyanhydride of l-phenylalanine. The resulting block copolymers were characterized by NMR spectrometry, IR spectroscopy, gel permeation chromatography, MALDI-TOF and UV-vis, revealing the successful incorporation of the polyphenylalanine (PPhe) peptide into the previously formed poly(l-lactide) (PLLA) polymer chain. X-ray diffraction and DSC data also suggested that the copolymers were phase-separated in domains containing either crystalline PLLA or PPhe phases. A peculiar thermal behavior was also found by thermogravimetric analysis when polyphenylalanine blocks were incorporated into polylactide. PMID:25075980

  9. N-valproyl-L-phenylalanine as new potential antiepileptic drug: synthesis, characterization and in vitro studies on stability, toxicity and anticonvulsant efficacy.

    PubMed

    De Caro, Viviana; Scaturro, Anna Lisa; Sutera, Flavia Maria; Avellone, Giuseppe; Schiera, Gabriella; Ferrantelli, Evelina; Carafa, Maria; Rizzo, Valerio; Carletti, Fabio; Sardo, Pierangelo; Giannola, Libero Italo

    2014-01-01

    Valproic acid (VPA) is considered first-line drug in treatment of generalized idiopathic seizures such as absence, generalized tonic-clonic and myoclonic seizures. Among major antiepileptic drugs, VPA is also considered effective in childhood epilepsies and infantile spasms. Due to its broad activity, VPA acts as a mood stabilizer in bipolar disorder and it is useful in migraine prophylaxis. Despite its long-standing usage, severe reactions to VPA, such as liver toxicity and teratogenicity, are reported. To circumvent side effects due to structural characteristics of VPA, we synthesized in good yield a new VPA-aminoacid conjugate, the N-valproyl-L-Phenylalanine, and characterized by FT-IR, MS, (13)C and (1)H- NMR analyses. The Log D(pH7.4) value (0.19) indicated that new molecule was potentially able to cross biological membranes. The resistance to chemical and enzymatic hydrolysis of N-valproyl-L-phenylalanine was also assessed. All trials suggested that the compound, at the pH conditions of the entire gastro-intestinal tract, remained unmodified. Furthermore, the new compound did not undergo enzymatic cleavage both in plasma and in cerebral medium up to 24 h. The toxicity assay on primary cultures of astrocytes indicated that the synthetized conjugate was less toxic than both free VPA and L-Phenylalanine. In this paper, the anticonvulsant activity of the new compound against epileptic burst discharges evoked in vitro in rat hippocampal slices was also evaluated. These preliminary results underline that N-valproyl-L-phenylalanine as new potential antiepileptic agent could represent a good candidate to further investigations.

  10. Identification of the Allosteric Site for Phenylalanine in Rat Phenylalanine Hydroxylase*

    PubMed Central

    Zhang, Shengnan; Fitzpatrick, Paul F.

    2016-01-01

    Liver phenylalanine hydroxylase (PheH) is an allosteric enzyme that requires activation by phenylalanine for full activity. The location of the allosteric site for phenylalanine has not been established. NMR spectroscopy of the isolated regulatory domain (RDPheH(25–117) is the regulatory domain of PheH lacking residues 1–24) of the rat enzyme in the presence of phenylalanine is consistent with formation of a side-by-side ACT dimer. Six residues in RDPheH(25–117) were identified as being in the phenylalanine-binding site on the basis of intermolecular NOEs between unlabeled phenylalanine and isotopically labeled protein. The location of these residues is consistent with two allosteric sites per dimer, with each site containing residues from both monomers. Site-specific variants of five of the residues (E44Q, A47G, L48V, L62V, and H64N) decreased the affinity of RDPheH(25–117) for phenylalanine based on the ability to stabilize the dimer. Incorporation of the A47G, L48V, and H64N mutations into the intact protein increased the concentration of phenylalanine required for activation. The results identify the location of the allosteric site as the interface of the regulatory domain dimer formed in activated PheH. PMID:26823465

  11. Detection of L-phenylalanine using molecularly imprinted solid-phase extraction and flow injection electrochemiluminescence.

    PubMed

    Lu, Juanjuan; Ge, Shenguang; Wan, Fuwei; Yu, Jinghua

    2012-01-01

    A novel flow injection electrochemiluminescence method combined with molecularly imprinted solid-phase extraction was developed for the determination of L-phenylalanine, in which ${\\rm{Ru(bpy}})_3^{2 + }$ was used as the luminophor and indium tin oxide glass was modified as the working electrode. Molecularly imprinted polymers, synthesized by self-assembly with functional monomer and crossing linker, were used for the selective extraction of L-phenylalanine. In order to overcome the drawbacks of traditional electrochemiluminescence cells such as high IR drop, high over-potential and so on, a novel electrochemiluminescence cell was developed. The enhanced electrochemiluminescence intensity was linearly related with the concentration of L-phenylalanine in the range from 1.0×10(-7) to 5.0×10(-5) g/mL with a detection limit of 2.59×10(-8) g/mL. The relative standard deviation for the determination of 1.0×10(-6) g/mL L-phenylalanine was 1.2% (n=11). The method showed higher sensitivity and good repeatability, and was successfully applied for the determination of L-phenylalanine in egg white, chicken and serum samples. A possible mechanism for the enhanced electrochemiluminescence response on indium tin oxide glass is proposed. Copyright © 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. The thermodynamic parameters of solution of L-phenylalanine in water

    NASA Astrophysics Data System (ADS)

    Kustov, A. V.; Korolev, V. P.

    2007-02-01

    The heat effects of solution of L-phenylalanine in water were measured over wide concentration and temperature ranges. The enthalpies of solution of L-phenylalanine were found to be independent of the content of the amino acid in solution over the concentration range studied. The standard enthalpies, heat capacities, and entropies of solution of the amino acid and the solubility of L-phenylalanine over the temperature range studied were calculated.

  13. Site-specific incorporation of 4-iodo-L-phenylalanine through opal suppression.

    PubMed

    Kodama, Koichiro; Nakayama, Hiroshi; Sakamoto, Kensaku; Fukuzawa, Seketsu; Kigawa, Takanori; Yabuki, Takashi; Kitabatake, Makoto; Takio, Koji; Yokoyama, Shigeyuki

    2010-08-01

    A variety of unique codons have been employed to expand the genetic code. The use of the opal (UGA) codon is promising, but insufficient information is available about the UGA suppression approach, which facilitates the incorporation of non-natural amino acids through suppression of the UGA codon. In this study, the UGA codon was used to incorporate 4-iodo-l-phenylalanine into position 32 of the Ras protein in an Escherichia coli cell-free translation system. The undesired incorporation of tryptophan in response to the UGA codon was completely repressed by the addition of indolmycin. The minor amount (3%) of contaminating 4-bromo-l-phenylalanine in the building block 4-iodo-l-phenylalanine led to the significant incorporation of 4-bromo-l-phenylalanine (21%), and this problem was solved by using a purified 4-iodo-l-phenylalanine sample. Optimization of the incubation time was also important, since the undesired incorporation of free phenylalanine increased during the cell-free translation reaction. The 4-iodo-l-phenylalanine residue can be used for the chemoselective modification of proteins. This method will contribute to advancements in protein engineering studies with non-natural amino acid substitutions.

  14. Spectroscopic characterization of Cu(II) complex of L-phenylalanine and D, L-tryptophan

    NASA Astrophysics Data System (ADS)

    Altun, Özlen; Bilcen, Selin

    2010-02-01

    In this work, the reactions involving L-phenylalanine and D, L-tryptophan in the presence of Cu(II) ion were studied. Optimum conditions for the reactions were established as pH 7 and λ = 641 nm. When the reaction was kinetic, it was observed that the following rate formula was found as dA/ An = k dt and k = 3.2 × 10 -4 s -1, according to absorbance measurements. Using a perpetual change curve, the ratio of [Cu]/[Cu] + L-phenylalanine + [ D, L-tryptophan] was found 1:1:1. According to this result, one molecule of L-phenylalanine and one molecule of D, L-tryptophan react with one molecule Cu(II) ion.

  15. (+/-)-3-[4-(2-dimethylamino-1-methylethoxy)-phenyl]-1H-pyrazolo[3,4- B]pyridine-1-acetic acid (Y-25510) stimulates production of IL-1 beta and IL-6 at the level of messenger RNA expression in cultured human monocytes.

    PubMed

    Kusuhara, H; Komatsu, H; Hisadome, M; Ikeda, Y

    1996-12-01

    (+/-)-3-[4-(2-Dimethylamino-1-methylethoxy)phenyl]-1H-pyrazolo[3, 4-b]pyridine-1-acetic acid (Y-25510) stimulated the mRNA expression for interleukin-1 beta (IL-1 beta), and enhanced the expression induced by lipopolysaccharide (LPS) in cultured human peripheral blood mononuclear cells (PBMC) and THP-1 cells, a cell-line derived from human monocytic leukemia. Y-25510 also stimulated the mRNA expression for IL-6 in both types of the cells, however, the stimulation required the presence of LPS. In THP-1 cells, the stimulation of IL-1 beta mRNA expression by Y-25510 was suppressed by cycloheximide, an inhibitor of protein synthesis. This phenomenon indicates that the stimulation requires de norv protein synthesis. In contrast, the stimulation of mRNA expression for IL-6 by Y-25510 was not suppressed by cycloheximide but suppressed by N alpha-p-tosyl-L-phenylalanine chloromethyl ketone (TPCK), an inhibitor of nuclear transcription factor-kappa B (NF-kappa B) activation, in the presence of LPS, suggesting that the stimulation requires NF-kappa activation. These results demonstrate that Y-25510 stimulates the mRNA expression for IL-1 beta and IL-6 by different mechanisms. Dexamethasone suppressed the LPS-induced expression of mRNA for IL-1 beta and IL-6 in THP-1 cells, whereas the drug never suppressed the mRNA expression for these cytokines in the presence of Y-25510. The result indicates that Y-25510 stimulates the mRNA expression for IL-1 beta and IL-6 by different mechanisms from those of LPS.

  16. Trypsin from the pyloric caeca of bluefish (Pomatomus saltatrix).

    PubMed

    Klomklao, Sappasith; Benjakul, Soottawat; Visessanguan, Wonnop; Kishimura, Hideki; Simpson, Benjamin K

    2007-12-01

    Trypsin was purified from the pyloric caeca of bluefish (Pomatomus saltatrix) by ammonium sulfate precipitation, acetone precipitation and soybean trypsin inhibitor-Sepharose 4B affinity chromatography. Bluefish trypsin migrated as a single band using both sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and native-PAGE and had a molecular mass of 28 kDa. The optima pH and temperature for the hydrolysis of benzoyl-dl-arginine-p-nitroanilide (BAPNA) were 9.5 and 55 degrees C, respectively. The enzyme was stable over a broad pH range (7 to 12), but was unstable at acidic pH, and at temperatures greater than 40 degrees C. The enzyme was inhibited by specific trypsin inhibitors: soybean trypsin inhibitor (SBTI), N-p-tosyl-l-lysine chloromethyl ketone (TLCK) and the serine protease inhibitor phenylmethyl sulfonylfluoride (PMSF). CaCl2 partially protected trypsin against activity loss at 40 degrees C, but NaCl (0 to 30%) decreased the activity in a concentration dependent manner. The N-terminal amino acid sequence of trypsin was determined as IVGGYECKPKSAPVQVSLNL and was highly homologous to other known vertebrate trypsins.

  17. Proteinase K-catalyzed synthesis of linear and star oligo(L-phenylalanine) conjugates.

    PubMed

    Ageitos, Jose M; Baker, Peter J; Sugahara, Michihiro; Numata, Keiji

    2013-10-14

    Chemoenzymatic synthesis of peptides is a green and clean chemical reaction that offers high yields without using organic synthesis and serves as an alternative to traditional peptide synthesis methods. This report describes the chemoenzymatic synthesis of oligo(L-phenylalanine) mediated by proteinase K from Tritirachium album, which is one of the most widely used proteases in molecular biological studies. The synthesized linear oligo-phenylalanine showed a unique self-assembly in aqueous solutions. To further functionalize linear oligo(L-phenylalanine) as a low-molecular-weight gelator, it was cosynthesized with tris(2-aminoethyl)amine to obtain star-oligo(L-phenylalanine), which was bioconjugated to demonstrate its self-assembly into fluorescent fibers. The self-assembled fibers of star-oligo(L-phenylalanine) formed fibrous networks with various branching ratios, which depended on the molecular weights and molecular aspect ratios of star-oligo(L-phenylalanine). This is the first study to demonstrate that proteinase K is a suitable enzyme for chemoenzymatic cosynthesis of oligopeptides and star-shaped heteropeptides.

  18. Synthesis of d- and l-Phenylalanine Derivatives by Phenylalanine Ammonia Lyases: A Multienzymatic Cascade Process.

    PubMed

    Parmeggiani, Fabio; Lovelock, Sarah L; Weise, Nicholas J; Ahmed, Syed T; Turner, Nicholas J

    2015-04-07

    The synthesis of substituted d-phenylalanines in high yield and excellent optical purity, starting from inexpensive cinnamic acids, has been achieved with a novel one-pot approach by coupling phenylalanine ammonia lyase (PAL) amination with a chemoenzymatic deracemization (based on stereoselective oxidation and nonselective reduction). A simple high-throughput solid-phase screening method has also been developed to identify PALs with higher rates of formation of non-natural d-phenylalanines. The best variants were exploited in the chemoenzymatic cascade, thus increasing the yield and ee value of the d-configured product. Furthermore, the system was extended to the preparation of those l-phenylalanines which are obtained with a low ee  value using PAL amination.

  19. Synthesis of d- and l-Phenylalanine Derivatives by Phenylalanine Ammonia Lyases: A Multienzymatic Cascade Process**

    PubMed Central

    Parmeggiani, Fabio; Lovelock, Sarah L; Weise, Nicholas J; Ahmed, Syed T; Turner, Nicholas J

    2015-01-01

    The synthesis of substituted d-phenylalanines in high yield and excellent optical purity, starting from inexpensive cinnamic acids, has been achieved with a novel one-pot approach by coupling phenylalanine ammonia lyase (PAL) amination with a chemoenzymatic deracemization (based on stereoselective oxidation and nonselective reduction). A simple high-throughput solid-phase screening method has also been developed to identify PALs with higher rates of formation of non-natural d-phenylalanines. The best variants were exploited in the chemoenzymatic cascade, thus increasing the yield and ee value of the d-configured product. Furthermore, the system was extended to the preparation of those l-phenylalanines which are obtained with a low ee value using PAL amination. PMID:25728350

  20. Reactions of aqueous L-methionine, L-phenylalanine, L-methionyl-L-phenylalanine, L-phenylalanyl-L-methionine and their mixtures with H atoms during steady radiolysis at pH 6. 5. [Gamma radiation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mee, L.K.; Adelstein, S.J.; Steinhart, C.M.

    Phenylalanine, methionine, and their mixtures, methionyl phenylalanine, phenylalnyl methionine, and mixtures of each dipeptide with phenylalanine were reacted with radiolytically generated H atoms in aqueous solution at pH 6.5. When methionine is irradiated alone, G(-methionine) = 2.0; the principal amino acid product is ..cap alpha..-amino-n-butyric acid. The initial destruction of phenylalanine, irradiated alone, is very low, G(-phenylalanine) approximately 0.15, and it decreases with dose. In mixtures of phenylalanine and methionine, radiolytic destruction of phenylalanine is potentiated, with a maximum potentiation at a phenylalanine:methionine ratio of 2 : 1. Repair reactions are postulated to account for the low initial yield ofmore » phenylalanine, its decrease with dose, and potentiation of destruction in mixtures with methionine. The destruction of the phenylalanyl and methionyl residues in the irradiated dipeptides is similar to that found for the loss of phenylalanine and methionine in 1 : 1 mixtures of the free amino acids; the destruction of residues in 1 : 1 mixtures of either dipeptide with phenylalanine is similar to that found in mixtures of phenylalanine:methionine at a ratio of 2 : 1. Thus, it is apparent already in simple mixtures of the divalent sulfur-containing methionine and the aromatic phenylalanine that kinetic interactions occur between these two kinds of amino acids which are not revealed by irradiation of these residues separately. The behavior of the dipeptides does not provide any evidence for intramolecular transfer of radical site.« less

  1. Synthesis of D- and L-phenylalanine derivatives by phenylalanine ammonia lyases: a multienzymatic cascade process.

    PubMed

    Parmeggiani, Fabio; Lovelock, Sarah L; Weise, Nicholas J; Ahmed, Syed T; Turner, Nicholas J

    2015-04-07

    The synthesis of substituted D-phenylalanines in high yield and excellent optical purity, starting from inexpensive cinnamic acids, has been achieved with a novel one-pot approach by coupling phenylalanine ammonia lyase (PAL) amination with a chemoenzymatic deracemization (based on stereoselective oxidation and nonselective reduction). A simple high-throughput solid-phase screening method has also been developed to identify PALs with higher rates of formation of non-natural D-phenylalanines. The best variants were exploited in the chemoenzymatic cascade, thus increasing the yield and ee value of the D-configured product. Furthermore, the system was extended to the preparation of those L-phenylalanines which are obtained with a low ee value using PAL amination. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Polymorphism and Modulation of Para-Substituted l-Phenylalanine.

    PubMed

    Sögütoglu, Leyla-Cann; Lutz, Martin; Meekes, Hugo; de Gelder, René; Vlieg, Elias

    2017-12-06

    The crystal structure of para -methyl-l-phenylalanine at 230 K resembles that of the para-fluorinated analogue from the literature but is commensurately modulated with seven molecules in the asymmetric unit ( Z ' = 7). At 100 K, the superstructure loses its modulation, leading to a unit cell with Z ' = 1, with clear disorder in the phenyl ring orientations. The methyl-substituent in para -methyl-l-phenylalanine has, in contrast to fluorine, no polar interactions with protons of neighboring molecules, which might allow for the well-defined modulation of the crystal structure at 230 K.

  3. Hidden overflow pathway to L-phenylalanine in Pseudomonas aeruginosa.

    PubMed Central

    Fiske, M J; Whitaker, R J; Jensen, R A

    1983-01-01

    Pseudomonas aeruginosa is representative of a large group of pseudomonad bacteria that possess coexisting alternative pathways to L-phenylalanine (as well as to L-tyrosine). These multiple flow routes to aromatic end products apparently account for the inordinate resistance of P. aeruginosa to end product analogs. Manipulation of carbon source nutrition produced a physiological state of sensitivity to p-fluorophenylalanine and m-fluorophenylalanine, each a specific antimetabolite of L-phenylalanine. Analog-resistant mutants obtained fell into two classes. One type lacked feedback sensitivity of prephenate dehydratase and was the most dramatic excretor of L-phenylalanine. The presence of L-tyrosine curbed phenylalanine excretion to one-third, a finding explained by potent early-pathway regulation of 3-deoxy-D-arabinoheptulosonate 7-phosphate (DAHP) synthase-Tyr (a DAHP synthase subject to allosteric inhibition by L-tyrosine). The second class of regulatory mutants possessed a completely feedback-resistant DAHP synthase-Tyr, the major species (greater than 90%) of two isozymes. Deregulation of DAHP synthase-Tyr resulted in the escape of most chorismate molecules produced into an unregulated overflow route consisting of chorismate mutase (monofunctional), prephenate aminotransferase, and arogenate dehydratase. In the wild type the operation of the overflow pathway is restrained by factors that restrict early-pathway flux. These factors include the highly potent feedback control of DAHP synthase isozymes by end products as well as the strikingly variable abilities of different carbon source nutrients to supply the aromatic pathway with beginning substrates. Even in the wild type, where all allosteric regulation in intact, some phenylalanine overflow was found on glucose-based medium, but not on fructose-based medium. This carbon source-dependent difference was much more exaggerated in each class of regulatory mutants. PMID:6132913

  4. Electrospray ionization mass spectrometry of mixtures of triterpene glycosides with L-phenylalanine

    NASA Astrophysics Data System (ADS)

    Lekar, A. V.; Vetrova, E. V.; Borisenko, N. I.; Yakovishin, L. A.; Grishkovets, V. I.; Borisenko, S. N.

    2011-09-01

    Electrospray-ionization mass spectrometry (ESI-MS) was used to investigate for the first time the molecular complexation of L-phenylalanine with hederagenin 3-O- α- L-rhamnopyranosyl-(1 → 2)-O- α- L-arabinopyranoside ( α-hederin) and its 28-O- α- L-rhamnopyranosyl-(1 → 4)-O-β- D-glucopyranosyl-(1 → 6)-O-β- D-glucopyranosyl ester (hederasaponin C). The glycoside/ L-phenylalanine complexes with a 1:1 molar ratio turned out to be most stable. The structures of the glycosides and L-phenylalanine have been concluded to have an impact on the complexation process.

  5. Enantioselective binding of L, D-phenylalanine to ct DNA

    NASA Astrophysics Data System (ADS)

    Zhang, Lijin; Xu, Jianhua; Huang, Yan; Min, Shungeng

    2009-10-01

    The enantioselective binding of L, D-phenylalanine to calf thymus DNA was studied by absorption, circular dichroism, fluorescence quenching, viscosity, salt effect and emission experiments. The results obtained from absorption, circular dichroism, fluorescence quenching and viscosity experiments excluded the intercalative binding and salt effect experiments did not support electrostatic binding. So the binding of L, D-phenylalanine to ct DNA should be groove binding. Furthermore, the emission spectra revealed that the binding is enantioselective.

  6. Enantioselective binding of L,D-phenylalanine to ct DNA.

    PubMed

    Zhang, Lijin; Xu, Jianhua; Huang, Yan; Min, Shungeng

    2009-10-15

    The enantioselective binding of L,D-phenylalanine to calf thymus DNA was studied by absorption, circular dichroism, fluorescence quenching, viscosity, salt effect and emission experiments. The results obtained from absorption, circular dichroism, fluorescence quenching and viscosity experiments excluded the intercalative binding and salt effect experiments did not support electrostatic binding. So the binding of l,d-phenylalanine to ct DNA should be groove binding. Furthermore, the emission spectra revealed that the binding is enantioselective.

  7. Terahertz spectra of l-phenylalanine and its monohydrate.

    PubMed

    Pan, Tingting; Li, Shaoping; Zou, Tao; Yu, Zheng; Zhang, Bo; Wang, Chenyang; Zhang, Jianbing; He, Mingxia; Zhao, Hongwei

    2017-05-05

    The low-frequency vibrational property of l-phenylalanine (l-Phe) and l-phenylalanine monohydrate (l-Phe·H 2 O) has been investigated by terahertz time-domain spectroscopy (THz-TDS) at room and low temperature ranging from 0.5 to 4.5THz. Distinctive THz absorption spectra of the two compounds were observed. Density functional theory (DFT) calculations based on the crystal structures have been performed to simulate the vibrational modes of l-Phe and l-Phe·H 2 O and the results agree well with the experimental observations. The study indicates that the characterized features of l-Phe mainly originate from the collective vibration of molecules. And the characterized features of l-Phe·H 2 O mainly come from hydrogen bond interactions between l-Phe and water molecules. l-Phe and l-Phe·H 2 O were also verified by differential scanning calorimetry and thermogravimetry (DSC-TG) and powder X-ray diffraction (PXRD) examinations. Copyright © 2017. Published by Elsevier B.V.

  8. Terahertz spectra of L-phenylalanine and its monohydrate

    NASA Astrophysics Data System (ADS)

    Pan, Tingting; Li, Shaoping; Zou, Tao; Yu, Zheng; Zhang, Bo; Wang, Chenyang; Zhang, Jianbing; He, Mingxia; Zhao, Hongwei

    2017-05-01

    The low-frequency vibrational property of L-phenylalanine (L-Phe) and L-phenylalanine monohydrate (L-Phe·H2O) has been investigated by terahertz time-domain spectroscopy (THz-TDS) at room and low temperature ranging from 0.5 to 4.5 THz. Distinctive THz absorption spectra of the two compounds were observed. Density functional theory (DFT) calculations based on the crystal structures have been performed to simulate the vibrational modes of L-Phe and L-Phe·H2O and the results agree well with the experimental observations. The study indicates that the characterized features of L-Phe mainly originate from the collective vibration of molecules. And the characterized features of L-Phe·H2O mainly come from hydrogen bond interactions between L-Phe and water molecules. L-Phe and L-Phe·H2O were also verified by differential scanning calorimetry and thermogravimetry (DSC-TG) and powder X-ray diffraction (PXRD) examinations.

  9. Enzymological Basis for Growth Inhibition by l-Phenylalanine in the Cyanobacterium Synechocystis sp. 29108

    PubMed Central

    Hall, Geraldine C.; Jensen, Roy A.

    1980-01-01

    The pattern of allosteric control in the biosynthetic pathway for aromatic amino acids provides a basis to explain vulnerability to growth inhibition by l-phenylalanine (0.2 mM or greater) in the unicellular cyanobacterium Synechocystis sp. 29108. We attribute growth inhibition to the hypersensitivity of 3-deoxy-d-arabinoheptulosonate 7-phosphate synthase to feedback inhibition by l-phenylalanine. Hyperregulation of this initial enzyme of aromatic biosynthesis depletes the supply of precursors needed for biosynthesis of l-tyrosine and l-tryptophan. Consistent with this mechanism is the total reversal of phenylalanine inhibition by a combination of tyrosine and tryptophan. Inhibited cultures also contained decreased levels of phycocyanin pigments, a characteristic previously correlated with amino acid starvation in cyanobacteria. l-Phenylalanine is a potent noncompetitive inhibitor (with both substrates) of 3-deoxy-d-arabinoheptulosonate 7-phosphate synthase, whereas l-tyrosine is a very weak inhibitor. Prephenate dehydratase also displays allosteric sensitivity to phenylalanine (inhibition) and to tyrosine (activation). Both 2-fluoro and 4-fluoro derivatives of phenylalanine were potent analog antimetabolites, and these were used in addition to l-phenylalanine as selective agents for resistant mutants. Mutants were isolated which excreted both phenylalanine and tyrosine, the consequence of an altered 3-deoxy-d-arabinoheptulosonate 7-phosphate synthase no longer sensitive to feedback inhibition. Simultaneous insensitivity to l-tyrosine suggests that l-tyrosine acts as a weak analog mimic of l-phenylalanine at a common binding site. Prephenate dehydratase in the regulatory mutants was unaltered. Surprisingly, in view of the lack of regulation in the tyrosine branchlet of the pathway, such mutants excrete more phenylalanine than tyrosine, indicating that l-tyrosine activation dominates l-phenylalanine inhibition of prephenate dehydratase in vivo. In mutant Phe r19 the

  10. 40 CFR 721.4925 - Methyl n-butyl ketone.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Methyl n-butyl ketone. 721.4925... Substances § 721.4925 Methyl n-butyl ketone. (a) Chemical substance and significant new use subject to reporting. (1) The chemical substance methyl n-butyl ketone, CAS Number 591-78-6, is subject to reporting...

  11. 40 CFR 721.4925 - Methyl n-butyl ketone.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Methyl n-butyl ketone. 721.4925... Substances § 721.4925 Methyl n-butyl ketone. (a) Chemical substance and significant new use subject to reporting. (1) The chemical substance methyl n-butyl ketone, CAS Number 591-78-6, is subject to reporting...

  12. 123/125I-labelled 2-iodo-L: -phenylalanine and 2-iodo-D: -phenylalanine: comparative uptake in various tumour types and biodistribution in mice.

    PubMed

    Kersemans, Veerle; Cornelissen, Bart; Kersemans, Ken; Bauwens, Matthias; Dierckx, Rudi A; De Spiegeleer, Bart; Mertens, John; Slegers, Guido

    2006-08-01

    In vitro in the R1M cell model and in vivo in the R1M tumour-bearing athymic model, both [(123)I]-2-iodo-L: -phenylalanine and [(123)I]-2-iodo-D: -phenylalanine have shown promising results as tumour diagnostic agents for SPECT. In order to compare these two amino acid analogues and to examine whether the observed characteristics could be generalised, both isomers were evaluated in various tumour models. Transport type characterisation in vitro in A549, A2058, C6, C32, Capan2, EF43fgf4, HT29 and R1M cells with [(123)I]-2-iodo-L: -phenylalanine was performed using the method described by Shotwell et al. Subsequently, [(123)I]-2-iodo-L: -phenylalanine and [(123)I]-2-iodo-D: -phenylalanine tumour uptake and biodistribution were evaluated using dynamic planar imaging and/or dissection in A549, A2058, C6, C32, Capan2, EF43fgf4, HT29 and R1M inoculated athymic mice. Two-compartment blood modelling of the imaging results was performed. In vitro testing demonstrated that [(123)I]-2-iodo-L: -phenylalanine was transported in all tumour cell lines by LAT1. In all tumour models, the two amino acid analogues showed the same general biodistribution characteristics: high and specific tumour uptake and renal tracer clearance. Two-compartment modelling revealed that the D: -isomer showed a faster blood clearance together with a faster distribution to the peripheral compartment in comparison with [(123)I]-2-iodo-L: -phenylalanine. [(123)I]-2-iodo-L: -phenylalanine and its D: -isomer are promising tumour diagnostic agents for dynamic planar imaging. They showed a high and similar uptake in all tested tumours. [(123)I]-2-iodo-D: -phenylalanine showed better tracer characteristics concerning radiation dose to other organs.

  13. Enhancement of L-phenylalanine production by engineered Escherichia coli using phased exponential L-tyrosine feeding combined with nitrogen source optimization.

    PubMed

    Yuan, Peipei; Cao, Weijia; Wang, Zhen; Chen, Kequan; Li, Yan; Ouyang, Pingkai

    2015-07-01

    Nitrogen source optimization combined with phased exponential L-tyrosine feeding was employed to enhance L-phenylalanine production by a tyrosine-auxotroph strain, Escherichia coli YP1617. The absence of (NH4)2SO4, the use of corn steep powder and yeast extract as composite organic nitrogen source were more suitable for cell growth and L-phenylalanine production. Moreover, the optimal initial L-tyrosine level was 0.3 g L(-1) and exponential L-tyrosine feeding slightly improved L-phenylalanine production. Nerveless, L-phenylalanine production was greatly enhanced by a strategy of phased exponential L-tyrosine feeding, where exponential feeding was started at the set specific growth rate of 0.08, 0.05, and 0.02 h(-1) after 12, 32, and 52 h, respectively. Compared with exponential L-tyrosine feeding at the set specific growth rate of 0.08 h(-1), the developed strategy obtained a 15.33% increase in L-phenylalanine production (L-phenylalanine of 56.20 g L(-1)) and a 45.28% decrease in L-tyrosine supplementation. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  14. Interaction of L-Phenylalanine with a Phospholipid Monolayer at the Water-Air Interface.

    PubMed

    Griffith, Elizabeth C; Perkins, Russell J; Telesford, Dana-Marie; Adams, Ellen M; Cwiklik, Lukasz; Allen, Heather C; Roeselová, Martina; Vaida, Veronica

    2015-07-23

    The interaction of L-phenylalanine with a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) monolayer at the air-water interface was explored using a combination of experimental techniques and molecular dynamics (MD) simulations. By means of Langmuir trough methods and Brewster angle microscopy, L-phenylalanine was shown to significantly alter the interfacial tension and the surface domain morphology of the DPPC film. In addition, confocal microscopy was used to explore the aggregation state of L-phenylalanine in the bulk aqueous phase. Finally, MD simulations were performed to gain molecular-level information on the interactions of L-phenylalanine and DPPC at the interface. Taken together, these results show that L-phenylalanine intercalates into a DPPC film at the air-water interface, thereby affecting the surface tension, phase morphology, and ordering of the DPPC film. The results are discussed in the context of biological systems and the mechanism of diseases such as phenylketonuria.

  15. The genetic incorporation of p-azidomethyl-l-phenylalanine into proteins in yeast.

    PubMed

    Supekova, Lubica; Zambaldo, Claudio; Choi, Seihyun; Lim, Reyna; Luo, Xiaozhou; Kazane, Stephanie A; Young, Travis S; Schultz, Peter G

    2018-05-15

    The noncanonical amino acid p-azidomethyl-l-phenylalanine can be genetically incorporated into proteins in bacteria, and has been used both as a spectroscopic probe and for the selective modification of proteins by alkynes using click chemistry. Here we report identification of Escherichia coli tyrosyl tRNA synthetase mutants that allow incorporation of p-azidomethyl-l-phenylalanine into proteins in yeast. When expressed together with the cognate E. coli tRNA CUA Tyr , the new mutant tyrosyl tRNA synthetases directed robust incorporation of p-azidomethyl-l-phenylalanine into a model protein, human superoxide dismutase, in response to the UAG amber nonsense codon. Mass spectrometry analysis of purified superoxide dismutase proteins confirmed the efficient site-specific incorporation of p-azidomethyl-l-phenylalanine. This work provides an additional tool for the selective modification of proteins in eukaryotic cells. Copyright © 2018 Elsevier Ltd. All rights reserved.

  16. Anomalous conformer dependent S 1 lifetime of L-phenylalanine

    NASA Astrophysics Data System (ADS)

    Hashimoto, Takayo; Takasu, Yuichi; Yamada, Yuji; Ebata, Takayuki

    2006-04-01

    The fluorescence lifetimes were measured for six conformers of L-phenylalanine cooled in a supersonic jet. It was found that the S 1 state lifetimes differ by a factor of three among the conformers. Especially, the most stable conformer (intramolecular hydrogen-bonded form) in S 0 had the shortest lifetime. Time-dependent DFT calculation suggested an importance of the mixing of the nπ ∗ character to S 1(ππ ∗) in this conformer dependent dynamics.

  17. Cross-linked enzyme aggregates of phenylalanine ammonia lyase: novel biocatalysts for synthesis of L-phenylalanine.

    PubMed

    Cui, Jian-Dong; Zhang, Si; Sun, Li-Mei

    2012-06-01

    Cross-linked enzyme aggregates of phenylalanine ammonia lyase (PAL-CLEAs) from Rhodotorula glutinis were prepared. The effects of the type of aggregating agent, its concentration, and that of cross-linking agent were studied. PAL-CLEAs production was most effective using ammonium sulfate (40 % saturation), followed by cross-linking for 1 h with 0.2 % (v/v) glutaraldehyde. Moreover, the storage and operational stability of the resulting PAL-CLEAs were also investigated. Compared to the free enzyme, the PAL-CLEAs exhibited the expected increased stability of the enzyme against various deactivating conditions such as pH, temperature, denaturants, and organic solvents and showed higher storage stability than its soluble counterpart. Additionally, the reusability of PAL-CLEAs with respect to the biotransformation of L-phenylalanine was evaluated. PAL-CLEAs could be recycled at least for 12 consecutive batch reactions without dramatic activity loss, which should dramatically increase the commercial potential of PAL for synthesis of L: -phenylalanine. To the best of our knowledge, this is the first report of immobilization of PAL as cross-linked enzyme aggregates.

  18. Poly(styrene-co-N-methacryloyl-l-phenylalanine methyl ester)-functionalized magnetic nanoparticles as sorbents for the analysis of sodium benzoate in beverages.

    PubMed

    Ji, Shilei; Li, Nan; Qi, Li; Wang, Minglin

    2017-01-01

    In this study, poly(styrene-co-N-methacryloyl-l-phenylalanine methyl ester)-functionalized magnetic nanoparticles were constructed and used as magnetic solid-phase extraction sorbents for analysis of food preservatives in beverages. To prepare the poly(amino acid)-based sorbents, N-methacryloyl-l-phenylalanine methyl ester, and styrene served as the functional monomers and modified onto the magnetic nanoparticles via free radical polymerization. Interestingly, compared with propylparaben and potassium sorbate, the proposed poly(amino acid)-based sorbents showed a good selectivity to sodium benzoate. The adsorption capacity of the sorbents to sodium benzoate was 6.08 ± 0.31 mg/g. Moreover, the fast adsorption equilibrium could be reached within 5 min. Further, the resultant poly(amino acid)-based sorbents were applied in the analysis of sodium benzoate in real beverage samples. The results proved that the proposed magnetic solid-phase extraction sorbents have a great potential for the analysis of preservatives in food samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Sensitive, Site-Specific, and Stable Vibrational Probe of Local Protein Environments: 4-Azidomethyl-L-Phenylalanine

    PubMed Central

    Bazewicz, Christopher G.; Liskov, Melanie T.; Hines, Kevin J.; Brewer, Scott H.

    2013-01-01

    We have synthesized the unnatural amino acid (UAA), 4-azidomethyl-Lphenylalanine (pN3CH2Phe), to serve as an effective vibrational reporter of local protein environments. The position, extinction coefficient, and sensitivity to local environment of the azide asymmetric stretch vibration of pN3CH2Phe are compared to the vibrational reporters: 4-cyano-L-phenylalanine (pCNPhe) and 4-azido-L-phenylalanine (pN3Phe). This UAA was genetically incorporated in a site-specific manner utilizing an engineered, orthogonal aminoacyl-tRNA synthetase in response to an amber codon with high efficiency and fidelity into two distinct sites in superfolder green fluorescent protein (sfGFP). This allowed for the dependence of the azide asymmetric stretch vibration of pN3CH2Phe to different protein environments to be measured. The photo-stability of pN3CH2Phe was also measured relative to the photoreactive UAA, pN3Phe. PMID:23865850

  20. Palladium-catalyzed three-component reaction of N-tosyl hydrazones, isonitriles and amines leading to amidines.

    PubMed

    Dai, Qiang; Jiang, Yan; Yu, Jin-Tao; Cheng, Jiang

    2015-12-04

    A palladium-catalyzed three-component reaction between N-tosyl hydrazones, aryl isonitriles and amines was developed, leading to amidines in moderate to good yields. This procedure features the rapid construction of amidine frameworks with high diversity and complexity. Ketenimines serve as intermediates, which encounter nucleophilic attack by amines to produce amidines.

  1. Missense Mutations in the N-Terminal Domain of Human Phenylalanine Hydroxylase Interfere with Binding of Regulatory Phenylalanine

    PubMed Central

    Gjetting, Torben; Petersen, Marie; Guldberg, Per; Güttler, Flemming

    2001-01-01

    Hyperphenylalaninemia due to a deficiency of phenylalanine hydroxylase (PAH) is an autosomal recessive disorder caused by >400 mutations in the PAH gene. Recent work has suggested that the majority of PAH missense mutations impair enzyme activity by causing increased protein instability and aggregation. In this study, we describe an alternative mechanism by which some PAH mutations may render PAH defective. Database searches were used to identify regions in the N-terminal domain of PAH with homology to the regulatory domain of prephenate dehydratase (PDH), the rate-limiting enzyme in the bacterial phenylalanine biosynthesis pathway. Naturally occurring N-terminal PAH mutations are distributed in a nonrandom pattern and cluster within residues 46–48 (GAL) and 65–69 (IESRP), two motifs highly conserved in PDH. To examine whether N-terminal PAH mutations affect the ability of PAH to bind phenylalanine at the regulatory domain, wild-type and five mutant (G46S, A47V, T63P/H64N, I65T, and R68S) forms of the N-terminal domain (residues 2–120) of human PAH were expressed as fusion proteins in Escherichia coli. Binding studies showed that the wild-type form of this domain specifically binds phenylalanine, whereas all mutations abolished or significantly reduced this phenylalanine-binding capacity. Our data suggest that impairment of phenylalanine-mediated activation of PAH may be an important disease-causing mechanism of some N-terminal PAH mutations, which may explain some well-documented genotype-phenotype discrepancies in PAH deficiency. PMID:11326337

  2. Rational design of aminoacyl-tRNA synthetase specific for p-acetyl-L-phenylalanine.

    PubMed

    Sun, Renhua; Zheng, Heng; Fang, Zhengzhi; Yao, Wenbing

    2010-01-01

    The Methanococcus jannaschii tRNA(Tyr)/tyrosyl-tRNA synthetase pair has been engineered to incorporate unnatural amino acids into proteins in Escherichia coli site-specifically. In order to add other unnatural amino acids into proteins by this approach, the amino acid binding site of M. jannaschii tyrosyl-tRNA synthetase need to be mutated. The crystal structures of M. jannaschii tyrosyl-tRNA synthetase and its mutations were determined, which provided an opportunity to design aminoacyl-tRNA synthetases specific for other unnatural amino acids. In our study, we attempted to design aminoacyl-tRNA synthetases being able to deliver p-acetyl-L-phenylalanine into proteins. p-Acetyl-L-phenylalanine was superimposed on tyrosyl in M. jannaschii tyrosyl-tRNA synthetase-tyrosine complex. Tyr32 needed to be changed to non-polar amino acid with shorter side chain, Val, Leu, Ile, Gly or Ala, in order to reduce steric clash and provide hydrophobic environment to acetyl on p-acetyl-L-phenylalanine. Asp158 and Ile159 would be changed to specific amino acids for the same reason. So we designed 60 aminoacyl-tRNA synthetases. Binding of these aminoacyl-tRNA synthetases with p-acetyl-L-phenylalanine indicated that only 15 of them turned out to be able to bind p-acetyl-L-phenylalanine with reasonable poses. Binding affinity computation proved that the mutation of Tyr32Leu and Asp158Gly benefited p-acetyl-L-phenylalanine binding. And two of the designed aminoacyl-tRNA synthetases had considerable binding affinities. They seemed to be very promising to be able to incorporate p-acetyl-L-phenylalanine into proteins in E. coli. The results show that the combination of homology modeling and molecular docking is a feasible method to filter inappropriate mutations in molecular design and point out beneficial mutations. Copyright 2009 Elsevier Inc. All rights reserved.

  3. Evaluation of the neuronal apoptotic pathways involved in cytoskeletal disruption-induced apoptosis.

    PubMed

    Jordà, Elvira G; Verdaguer, Ester; Jimenez, Andrés; Arriba, S Garcia de; Allgaier, Clemens; Pallàs, Mercè; Camins, Antoni

    2005-08-01

    The cytoskeleton is critical to neuronal functioning and survival. Cytoskeletal alterations are involved in several neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. We studied the possible pathways involved in colchicine-induced apoptosis in cerebellar granule neurons (CGNs). Although colchicine evoked an increase in caspase-3, caspase-6 and caspase-9 activation, selective caspase inhibitors did not attenuate apoptosis. Inhibitors of other cysteine proteases such as PD150606 (a calpain-specific inhibitor), Z-Phe-Ala fluoromethyl ketone (a cathepsins-inhibitors) and N(alpha)-p-tosyl-l-lysine chloromethyl ketone (serine-proteases inhibitor) also had no effect on cell death/apoptosis induced by colchicine. However, BAPTA-AM 10 microM (intracellular calcium chelator) prevented apoptosis mediated by cytoskeletal alteration. These data indicate that calcium modulates colchicine-induced apoptosis in CGNs. PARP-1 inhibitors did not prevent apoptosis mediated by colchicine. Finally, colchicine-induced apoptosis in CGNs was attenuated by kenpaullone, a cdk5 inhibitor. Kenpaullone and indirubin also prevented cdk5/p25 activation mediated by colchicine. These findings indicate that cytoskeletal alteration can compromise cdk5 activation, regulating p25 formation and suggest that cdk5 inhibitors attenuate apoptosis mediated by cytoskeletal alteration. The present data indicate the potential therapeutic value of drugs that prevent the formation of p25 for the treatment of neurodegenerative disorders.

  4. A novel chiral separation material: polymerized organogel formed by chiral gelators for the separation of D- and L-phenylalanine.

    PubMed

    Fu, Xinjian; Yang, Yang; Wang, Ningxia; Wang, Hong; Yang, Yajiang

    2007-01-01

    N-Stearine-N'-stearyl-L-phenylalanine, a chiral compound, was synthesized and used as a gelator for the gelation of polymerizable solvents, such as ss-hydroxyethyl methacrylate (HEMA), styrene, etc. The scanning electron microscope (SEM) images of the gelator aggregates show fibril-like helices, typical chiral aggregates with diameters of 100-200 nm. The solvent molecules were immobilized by capillary forces in the three-dimensional network structures of the organogels. The HEMA organogels containing crosslinker polyethylene glycol dimethacrylates (PEG200DMA) were subsequently polymerized by in situ UV irradiation. A porous polymerized organogels were obtained after removal of gelator aggregates through ethanol extraction. The chiral separation of D- and L-phenylalanine was carried out by the adsorption of the polymerized organogels. The adsorption efficiency of L-phenylalanine on the polymerized organogels was found to be dependent on the concentration of the gelator and crosslinker. (c) 2007 John Wiley & Sons, Ltd.

  5. Expanding the utility of 4-cyano-L-phenylalanine as a vibrational reporter of protein environments.

    PubMed

    Bazewicz, Christopher G; Lipkin, Jacob S; Smith, Emily E; Liskov, Melanie T; Brewer, Scott H

    2012-09-06

    The ability to genetically incorporate amino acids modified with spectroscopic reporters site-specifically into proteins with high efficiency and fidelity has greatly enhanced the ability to probe local protein structure and dynamics. Here, we have synthesized the unnatural amino acid (UAA), 4-cyano-L-phenylalanine (pCNPhe), containing the nitrile vibrational reporter and three isotopomers ((15)N, (13)C, (13)C(15)N) of this UAA to enhance the ability of pCNPhe to study local protein environments. Each pCNPhe isotopic variant was genetically incorporated in an efficient, site-specific manner into superfolder green fluorescent protein (sfGFP) in response to an amber codon with high fidelity utilizing an engineered, orthogonal aminoacyl-tRNA synthetase. The isotopomers of 4-cyano-L-phenylalanine permitted the nitrile symmetric stretch vibration of these UAAs to be unambiguously assigned utilizing the magnitude and direction of the isotopic shift of this vibration. The sensitivity of the nitrile symmetric stretching frequency of each isotopic variant to the local environment was measured by individually incorporating the probes into two distinct local environments of sfGFP. The UAAs were also utilized in concert to probe multiple local environments in sfGFP simultaneously to increase the utility of 4-cyano-L-phenylalanine.

  6. Preparation of imprinted cryogel cartridge for chiral separation of l-phenylalanine.

    PubMed

    Akgönüllü, Semra; Yavuz, Handan; Denizli, Adil

    2017-06-01

    l-Phe-imprinted cryogel cartridge was prepared for the chiral separation of l-Phe. N-Methacryloyl l-phenylalanine (MAPA) was used as a functional monomer for complexing with l-Phe. The selectivity of the membranes was investigated by using d-Phe, l-Trp, and d-Trp as competitor molecules. The PHEMAPA-l-Trp membranes were 6.4, 4.3, and 5.5 times more selective for l-Phe than d-Phe, l-Trp, and d-Trp, respectively. The PHEMAPA-l-Phe cryogel cartridge was incorporated into the fast protein liquid chromatography (FPLC) equipment and was able to separate D,l-Phe racemic mixture efficiently. The PHEMAPA-l-Phe membranes were shown to be reusable many times without significant loss of the adsorption capacity.

  7. Bacterial conversion of phenylalanine and aromatic carboxylic acids into dihydrodiols.

    PubMed Central

    Wegst, W; Tittmann, U; Eberspächer, J; Lingens, F

    1981-01-01

    Strain E of chloridazon-degrading bacteria, when grown on L-phenylalanine accumulates cis-2,3-dihydro-2,3-dihydroxyphenylalanine. In experiments with resting cells and during growth the bacterium converts the aromatic carboxylic acids phenylacetate, phenylpropionate, phenylbutyrate and phenyl-lactate into the corresponding cis-2,3-dihydrodiol compounds. The amino acids L-phenylalanine, N-acetyl-L-phenylalanine and t-butyloxycarbonyl-L-phenylalanine were also transformed into dihydrodiols. All seven dihydrodiols, thus obtained, were characterized both by conventional analytical techniques and by the ability to serve as substrates for a cis-dihydrodiol dehydrogenase. PMID:7306016

  8. L-Phenylalanine and L-tyrosine catabolism by selected Streptomyces species

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pometto, A.L. III; Crawford, D.L.

    L-Phenylalanine and L-tyrosine were completely catabolized through homogentisate by Streptomyces setonii 75Vi2 but only partially degraded by Streptomyces badius 252, Streptomyces sioyaensis P5, Streptomyces viridosporus T7A, and Streptomyces sp. strain V7. Intermediates of catabolism were confirmed by the thin-layer, gas, and high-pressure liquid chromatography. Homogentisate 1,2-dioxygenase was present in all cell extracts.

  9. L-Phenylalanine and L-tyrosine catabolism by selected Streptomyces species.

    PubMed Central

    Pometto, A L; Crawford, D L

    1985-01-01

    L-Phenylalanine and L-tyrosine were completely catabolized through homogentisate by Streptomyces setonii 75Vi2 but only partially degraded by Streptomyces badius 252, Streptomyces sioyaensis P5, Streptomyces viridosporus T7A, and Streptomyces sp. strain V7. Intermediates of catabolism were confirmed by thin-layer, gas, and high-pressure liquid chromatography. Homogentisate 1,2-dioxygenase was present in all cell extracts. PMID:3994376

  10. Intramolecular interactions of L-phenylalanine revealed by inner shell chemical shift

    NASA Astrophysics Data System (ADS)

    Ganesan, Aravindhan; Wang, Feng

    2009-07-01

    Intramolecular interactions of the functional groups, carboxylic acid, amino, and phenyl in L-phenylalanine have been revealed through inner shell chemical shift. The chemical shift and electronic structures are studied using its derivatives, 2-phenethylamine (PEA) and 3-phenylpropionic acid (PPA), through substitutions of the functional groups on the chiral carbon Cα, i.e., carboxylic acid (-COOH) and amino (-NH2) groups. Inner shell ionization spectra of L-phenylalanine are simulated using density functional theory based B3LYP/TZVP and LB94/et-pVQZ models, which achieve excellent agreement with the most recently available synchrotron sourced x-ray photoemission spectroscopy of L-phenylalanine (Elettra, Italy). The present study reveals insight into behavior of the peptide bond (CO-NH) through chemical shift of the C1-Cα-Cβ(-Cγ) chain and intramolecular interactions with phenyl. It is found that the chemical shift of the carbonyl C1(=O) site exhibits an apparently redshift (smaller energy) when interacting with the phenyl aromatic group. Removal of the amino group (-NH2) from L-phenylalanine (which forms PPA) brings this energy on C1 close to that in L-alanine (δ <0.01 eV). Chemical environment of Cα and Cβ exhibits more significant differences in L-alanine than in the aromatic species, indicating that the phenyl group indeed affects the peptide bond in the amino acid fragment. No direct evidences are found that the carbonyl acid and amino group interact with the phenyl ring through conventional hydrogen bonds.

  11. Myricetin down-regulates phorbol ester-induced cyclooxygenase-2 expression in mouse epidermal cells by blocking activation of nuclear factor kappa B.

    PubMed

    Lee, Kyung Mi; Kang, Nam Joo; Han, Jin Hee; Lee, Ki Won; Lee, Hyong Joo

    2007-11-14

    Abnormal expression of cyclooxygenase-2 (COX-2) has been implicated in the development of cancer. There are multiple lines of evidence that red wine exerts chemopreventive effects, and 3,5,4'-trihydroxy- trans-stilbene (resveratrol), which is a non-flavonoid polyphenol found in red wine, has been reported to be a natural chemopreventive agent. However, other phytochemicals might contribute to the cancer-preventive activities of red wine, and the flavonol content of red wines is about 30 times higher than that of resveratrol. Here we report that 3,3',4',5,5',7-hexahydroxyflavone (myricetin), one of the major flavonols in red wine, inhibits 12-O-tetradecanoylphorbol-13-acetate (phorbol ester)-induced COX-2 expression in JB6 P+ mouse epidermal (JB6 P+) cells by suppressing activation of nuclear factor kappa B (NF-kappaB). Myricetin at 10 and 20 microM inhibited phorbol ester-induced upregulation of COX-2 protein, while resveratrol at the same concentration did not exert significant effects. The phorbol ester-induced production of prostaglandin E 2 was also attenuated by myricetin treatment. Myricetin inhibited both COX-2 and NF-kappaB transactivation in phorbol ester-treated JB6 P+ cells, as determined using a luciferase assay. Myricetin blocked the phorbol ester-stimulated DNA binding activity of NF-kappaB, as determined using an electrophoretic mobility shift assay. Moreover, TPCK (N-tosyl-l-phenylalanine chloromethyl ketone), a NF-kappaB inhibitor, significantly attenuated COX-2 expression and NF-kappaB promoter activity in phorbol ester-treated JB6 P+ cells. In addition, red wine extract inhibited phorbol ester-induced COX-2 expression and NF-kappaB transactivation in JB6 P+ cells. Collectively, these data suggest that myricetin contributes to the chemopreventive effects of red wine through inhibition of COX-2 expression by blocking the activation of NF-kappaB.

  12. Influence of additive L-phenylalanine on stabilization of metastable α-form of L-glutamic acid in cooling crystallization

    NASA Astrophysics Data System (ADS)

    Quang, Khuu Chau; Nhan, Le Thi Hong; Huyen, Trinh Thi Thanh; Tuan, Nguyen Anh

    2017-09-01

    The influence of additive amino acid L-phenylalanine on stabilization of metastable α-form of L-glutamic acid was investigated in cooling crystallization. The present study found that the additive L-phenylalanine could be used to stabilize the pure metastable α-form in L-glutamic acid crystallization, where the additive concentration of 0.05-0.1 (g/L) was sufficient to stabilize the 100% wt metastable α-form in solid product at L-glutamic acid concentration of 30-45 (g/L). Additionally, the present results indicated that the adsorption of additive L-phenylalanine on the (001) surface of α-form was more favorable than that of the β-form molecular, so the nucleation sites of stable β-form was occupied by additive molecular, which resulted in inhibition of nucleation and growth of β-form, allowing stabilization of metastable α-form.

  13. Chloromethyl-oxirane and chloromethyl-thiirane in liquid phase: A joint experimental and quantum chemical study

    NASA Astrophysics Data System (ADS)

    Campetella, M.; Bencivenni, L.; Caminiti, R.; Zazza, C.; Di Trapani, S.; Martino, A.; Gontrani, L.

    2016-07-01

    The X-ray diffraction spectra of liquid chloromethyl-oxirane (ClMO) and chloromethyl-thiirane (ClMT) have been recorded for the first time. The interpretation of X-ray measurements was based on ab initio molecular dynamics simulations at finite temperature conditions. Both liquids show conformational equilibrium, which is discussed in terms of Gauche-2, Gauche-1 and Cis structures. The occurrence of the various forms estimated from X-ray and AIMD data has been compared with spectroscopy data from the literature, with the FTIR spectra of the liquids newly recorded in this work, and with theoretical in vacuo calculations.

  14. Novel strategy for phenyllactic acid biosynthesis from phenylalanine by whole cell recombinant Escherichia coli coexpressing L-phenylalanine oxidase and L-lactate dehydrogenase.

    PubMed

    Zhang, Jianzhi; Li, Xi

    2018-01-01

    To enhance the efficiency of phenyllactic acid (PLA) production from L-phenylalanine (L-Phe) by introducing a novel artificial pathway into Escherichia coli RESULTS: The production of PLA from L-Phe by recombinant E. coli (ldh-lpox) coexpressing L-phenylalanine oxidase and L-lactate dehydrogenase was studied. The new PLA synthesis pathway was confirmed to be efficient in recombinant E. coli. Subsequently, two different biocatalyst processes were carried out and optimized for PLA production. In the whole cell biosynthesis process at high cell density using collected recombinant cells as catalyst, at optimal conditions (L-Phe 6 g/l, pH 7.5, 35 °C, CDW 24.5 g/l and 200 rpm), the recombinant E. coli (ldh-lpox) produced 1.62 g PLA/l with a conversion of 28% from L-Phe. Similarly, during the two-temperature-stage fermentation process in flasks using IPTG-induced cells, the temperature in the second stage was increased to 35 °C to benefit the biocatalyst process, and comparable phenyllactic acid production of 1.47 g/l was obtained from 12 g L-Phe/l. Recombinant E. coli (ldh-lpox) was efficient in PLA production realizing a high titer of several folds compared with studies using L-Phe as substrate.

  15. Glycomacropeptide in children with phenylketonuria: does its phenylalanine content affect blood phenylalanine control?

    PubMed

    Daly, A; Evans, S; Chahal, S; Santra, S; MacDonald, A

    2017-08-01

    In phenylketonuria (PKU), there are no data available for children with respect to evaluating casein glycomacropeptide (CGMP) as an alternative to phenylalanine-free protein substitutes [Phe-free L-amino acid (AA)]. CGMP contains a residual amount of phenylalanine, which may alter blood phenylalanine control. In a prospective 6-month pilot study, we investigated the effect on blood phenylalanine control of CGMP-amino acid (CGMP-AA) protein substitute in 22 PKU subjects (13 boys, nine girls), median age (range) 11 years (6-16 years). Twelve received CGMP-AA and nine received Phe-free L-AA, (1 CGMP-AA withdrawal). Subjects partially or wholly replaced Phe-free L-AA with CGMP-AA. If blood phenylalanine exceeded the target range, the CGMP-AA dose was reduced and replaced with Phe-free L-amino acids. The control group remained on Phe-free L-AAs. Phenylalanine, tyrosine and Phe : Tyr ratio concentrations were compared with the results for the previous year. In the CGMP-AA group, there was a significant increase in blood phenylalanine concentrations (pre-study, 275 μmol L -1 ; CGMP-AA, 317 μmol L -1 ; P = 0.02), a decrease in tyrosine concentrations (pre-study, 50 μmol L -1 ; CGMP-AA, 40 μmol L -1 ; P = 0.03) and an increase in Phe : Tyr ratios (pre-study, Phe : Tyr 4.9:1; CGMP-AA, Phe : Tyr 8:1; P = 0.02). In the control group there was a non-significant fall in phenylalanine concentrations (pre-study 325μmol/L: study 280μmol/L [p = 0.9], and no significant changes for tyrosine or phe/tyr ratios [p = 0.9]. Children taking the CGMP-AA found it more acceptable to L-AA. Blood phenylalanine control declined with CGMP-AA but, by titrating the dose of CGMP-AA, blood phenylalanine control remained within target range. The additional intake of phenylalanine may have contributed to the change in blood phenylalanine concentration. CGMP-AA use requires careful monitoring in children. © 2017 The British Dietetic Association Ltd.

  16. A potentiometric chiral sensor for L-Phenylalanine based on crosslinked polymethylacrylic acid-polycarbazole hybrid molecularly imprinted polymer.

    PubMed

    Chen, Yu; Chen, Lei; Bi, Ruilin; Xu, Lan; Liu, Yan

    2012-11-19

    A novel chiral molecularly imprinted polymer (MIP) sensor for L-Phenylalanine has been developed, which is constructed by electrochemically driven cross-linking a pendant polymer precursor, poly[2-(N-carbazolyl)ethyl methacrylate-co-meth-acrylic acid]s (PCEMMAs). In this MIP sensing material, the recognition sites, the insulating polymethylacrylic acid (PMAA), were covalently bonded to the conducting polycarbazole which could be used as signal transfer interface between recognition layer and electrode. The mole ratio of copolymerizing monomers, 2-(N-carbazolyl) ethyl methacrylate:methylacrylic acid (CE:MAA), and the scanning cycles of electropolymerization were adjusted during the preparation of MIP sensing material. The optimized conditions, CE:MAA=3:2 and 20 scanning cycles, were obtained. And then the properties of MIP films were characterized by atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS) and water contact angle. Open circuit potential-time technique was used to estimate the enantioselectivity of the MIP sensor. The results indicate that the promising sensor preferentially responses L-Phenylalanine (L-Phe) over D-Phenylalanine (D-Phe) with a selectivity coefficient K(D)(L)=5.75×10(-4) and the limit of detection (LOD) is 1.37μM, which reveals its good enantioselectivity and sensitivity. Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.

  17. The de novo engineering of pyrrolysyl-tRNA synthetase for genetic incorporation of L-phenylalanine and its derivatives.

    PubMed

    Wang, Yane-Shih; Russell, William K; Wang, Zhiyong; Wan, Wei; Dodd, Lindsey E; Pai, Pei-Jing; Russell, David H; Liu, Wenshe R

    2011-03-01

    Using evolved pyrrolysyl-tRNA synthetase-tRNA(CUA)(Pyl) pairs, L-phenylalanine, p-iodo-L-phenylalanine and p-bromo-L-phenylalanine have been genetically incorporated into proteins at amber mutation sites in E. coli.

  18. Enhancement of  l-phenylalanine production in Escherichia coli by heterologous expression of Vitreoscilla hemoglobin.

    PubMed

    Wu, Wei-Bin; Guo, Xiao-Lei; Zhang, Ming-Liang; Huang, Qing-Gen; Qi, Feng; Huang, Jian-Zhong

    2018-05-01

    l-Phenylalanine is an important amino acid that is widely used in the production of food flavors and pharmaceuticals. Generally, l-phenylalanine production by engineered Escherichia coli requires a high rate of oxygen supply. However, the coexpression of Vitreoscilla hemoglobin gene (vgb), driven bya tac promoter, with the genes encoding 3-deoxy-d-arabinoheptulosonate-7-phosphate synthetase (aroF) and feedback-resistant chorismate mutase/prephenate dehydratase (pheA fbr ), led to increased productivity and decreased demand for aeration by E. coli CICC10245. Shake-flask studies showed that vgb-expressing strains displayed higher rates of oxygen uptake, and l-phenylalanine production under standard aeration conditions was increased. In the aerobic fermentation process, cell growth, l-phenylalanine production, and glucose consumption by the recombinant E. coli strain PAPV, which harbored aroF, pheA fbr , and tac-vgb genes, were increased compared to that in the strain harboring only aroF and pheA fbr (E. coli strain PAP), especially under oxygen-limited conditions. The vgb-expressing strain PAPV produced 21.9% more biomass and 16.6% more l-phenylalanine, while consuming only approximately 5% more glucose after 48 H of fermentation. This study demonstrates a method to enhance the l-phenylalanine production by E. coli using less intensive and thus more economical aeration conditions. © 2017 International Union of Biochemistry and Molecular Biology, Inc.

  19. 27 CFR 21.118 - Methyl n-butyl ketone.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Methyl n-butyl ketone. 21.118 Section 21.118 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU....118 Methyl n-butyl ketone. (a) Acidity (as acetic acid). 0.02 percent by weight, maximum. (b) Color...

  20. 27 CFR 21.118 - Methyl n-butyl ketone.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Methyl n-butyl ketone. 21.118 Section 21.118 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU....118 Methyl n-butyl ketone. (a) Acidity (as acetic acid). 0.02 percent by weight, maximum. (b) Color...

  1. Genetic Incorporation of Twelve meta-Substituted Phenylalanine Derivatives Using A Single Pyrrolysyl-tRNA Synthetase

    PubMed Central

    Wang, Yane-Shih; Fang, Xinqiang; Chen, Hsueh-Ying; Wu, Bo; Wang, Zhiyong U.; Hilty, Christian; Liu, Wenshe R.

    2012-01-01

    When coexpressed with its cognate amber suppressing tRNACUAPyl, a pyrrolysyl-tRNA synthetase mutant N346A/C348A is able to genetically incorporate twelve meta-substituted phenylalanine derivatives into proteins site-specifically at amber mutation sites in Escherichia coli. These genetically encoded noncanonical amino acids resemble phenylalanine in size and contain diverse bioorthogonal functional groups such as halide, trifluoromethyl, nitrile, nitro, ketone, alkyne, and azide moieties. The genetic installation of these functional groups in proteins provides multiple ways to site-selectively label proteins with biophysical and biochemical probes for their functional investigations. We demonstrate that a genetically incorporated trifluoromethyl group can be used as a sensitive 19F NMR probe to study protein folding/unfolding, and that genetically incorporated reactive functional groups such as ketone, alkyne, and azide moieties can be applied to site-specifically label proteins with florescent probes. This critical discovery allows the synthesis of proteins with diverse bioorthogonal functional groups for a variety of basic studies and biotechnology development using a single recombinant expression system. PMID:23138887

  2. L-Phenylalanine Transport in Saccharomyces cerevisiae: Participation of GAP1, BAP2, and AGP1

    PubMed Central

    Sáenz, Daniel A.; Chianelli, Mónica S.; Stella, Carlos A.

    2014-01-01

    We focused on the participation of GAP1, BAP2, and AGP1 in L-phenylalanine transport in yeast. In order to study the physiological functions of GAP1, BAP2, and AGP1 in L-phenylalanine transport, we examined the kinetics, substrate specificity, and regulation of these systems, employing isogenic haploid strains with the respective genes disrupted individually and in combination. During the characterization of phenylalanine transport, we noted important regulatory phenomena associated with these systems. Our results show that Agp1p is the major transporter of the phenylalanine in a gap1 strain growing in synthetic media with leucine present as an inducer. In a wild type strain grown in the presence of leucine, when ammonium ion was the nitrogen source, Bap2p is the principal phenylalanine carrier. PMID:24701347

  3. Self-assembling N-(9-Fluorenylmethoxycarbonyl)-l-Phenylalanine hydrogel as novel drug carrier.

    PubMed

    Snigdha, Kirti; Singh, Brijesh K; Mehta, Abijeet Singh; Tewari, R P; Dutta, P K

    2016-12-01

    Supramolecular hydrogel as a novel drug carrier was prepared from N-(9-Fluorenylmethoxycarbonyl) (Fmoc) modified l-phenylalanine. Its different properties like stability at different pH, temperature and rheology were evaluated in reference to salicylic acid (SA) as a model drug, entrapped in the supramolecular hydrogel network. The release behaviour of SA drug in supramolecular hydrogel was investigated by UV-vis spectroscopy. The influence of hydrogelator, pH values of the accepting media, temperature and concentration of SA drug on the release behaviour was investigated under static conditions. The results indicated that the release rate of SA in the supramolecular hydrogels was slightly retarded with an increase of the hydrogelator concentration. Also, the release rates of SA increased with an increase of temperature and its concentration. Furthermore, the release behaviour of SA was found to be different at various pH values in buffers. The study of the release kinetics indicated that the release behaviour of SA from the carrier was in accord with the Peppas model and the diffusion controlled mechanism involved in the Fickian model. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Bis(chloromethyl)ether (BCME)

    Integrated Risk Information System (IRIS)

    Bis ( chloromethyl ) ether ( BCME ) ; CASRN 542 - 88 - 1 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments f

  5. Chloromethyl methyl ether (CMME)

    Integrated Risk Information System (IRIS)

    Chloromethyl methyl ether ( CMME ) ; CASRN 107 - 30 - 2 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments fo

  6. Novel Scheme for Biosynthesis of Aryl Metabolites from l-Phenylalanine in the Fungus Bjerkandera adusta

    PubMed Central

    Lapadatescu, Carmen; Giniès, Christian; Le Quéré, Jean-Luc; Bonnarme, Pascal

    2000-01-01

    Aryl metabolite biosynthesis was studied in the white rot fungus Bjerkandera adusta cultivated in a liquid medium supplemented with l-phenylalanine. Aromatic compounds were analyzed by gas chromatography-mass spectrometry following addition of labelled precursors (14C- and 13C-labelled l-phenylalanine), which did not interfere with fungal metabolism. The major aromatic compounds identified were benzyl alcohol, benzaldehyde (bitter almond aroma), and benzoic acid. Hydroxy- and methoxybenzylic compounds (alcohols, aldehydes, and acids) were also found in fungal cultures. Intracellular enzymatic activities (phenylalanine ammonia lyase, aryl-alcohol oxidase, aryl-alcohol dehydrogenase, aryl-aldehyde dehydrogenase, lignin peroxidase) and extracellular enzymatic activities (aryl-alcohol oxidase, lignin peroxidase), as well as aromatic compounds, were detected in B. adusta cultures. Metabolite formation required de novo protein biosynthesis. Our results show that l-phenylalanine was deaminated to trans-cinnamic acid by a phenylalanine ammonia lyase and trans-cinnamic acid was in turn converted to aromatic acids (phenylpyruvic, phenylacetic, mandelic, and benzoylformic acids); benzaldehyde was a metabolic intermediate. These acids were transformed into benzaldehyde, benzyl alcohol, and benzoic acid. Our findings support the hypothesis that all of these compounds are intermediates in the biosynthetic pathway from l-phenylalanine to aryl metabolites. Additionally, trans-cinnamic acid can also be transformed via β-oxidation to benzoic acid. This was confirmed by the presence of acetophenone as a β-oxidation degradation intermediate. To our knowledge, this is the first time that a β-oxidation sequence leading to benzoic acid synthesis has been found in a white rot fungus. A novel metabolic scheme for biosynthesis of aryl metabolites from l-phenylalanine is proposed. PMID:10742235

  7. Isolation and Synthetic Diversification of Jadomycin 4-Amino-l-phenylalanine.

    PubMed

    Martinez-Farina, Camilo F; Robertson, Andrew W; Yin, Huimin; Monro, Susan; McFarland, Sherri A; Syvitski, Raymond T; Jakeman, David L

    2015-06-26

    Streptomyces venezuelae ISP5230 was grown in the presence of phenylalanine analogues to observe whether they could be incorporated into novel jadomycin structures. It was found that the bacteria successfully produced jadomycins incorporating 4-aminophenylalanine enantiomers. Upon isolation and characterization of jadomycin 4-amino-l-phenylalanine (1), it was synthetically derivatized, using activated succinimidyl esters, to yield a small jadomycin amide library. These are the first examples of oxazolone-ring-containing jadomycins that have incorporated an amino functionality subsequently used for derivatization.

  8. Co-expression of five genes in E coli for L-phenylalanine in Brevibacterium flavum

    PubMed Central

    Wu, Yong-Qing; Jiang, Pei-Hong; Fan, Chang-Sheng; Wang, Jian-Gang; Shang, Liang; Huang, Wei-Da

    2003-01-01

    AIM: To study the effect of co-expression of ppsA, pckA, aroG, pheA and tyrB genes on the production of L-phenylalanine, and to construct a genetic engineering strain for L-phenylalanine. METHODS: ppsA and pckA genes were amplified from genomic DNA of E. coli by polymerase chain reaction, and then introduced into shuttle vectors between E coli and Brevibacterium flavum to generate constructs pJN2 and pJN5. pJN2 was generated by inserting ppsA and pckA genes into vector pCZ; whereas pJN5 was obtained by introducing ppsA and pckA genes into pCZ-GAB, which was originally constructed for co-expression of aroG, pheA and tyrB genes. The recombinant plasmids were then introduced into B. flavum by electroporation and the transformants were used for L-phenylalanine fermentation. RESULTS: Compared with the original B. flavum cells, all the transformants were showed to have increased five enzyme activities specifically, and have enhanced L-phenylalanine biosynthesis ability variably. pJN5 transformant was observed to have the highest elevation of L-phenylalanine production by a 3.4-fold. Co-expression of ppsA and pckA increased activity of DAHP synthetase significantly. CONCLUSION: Co-expression of ppsA and pckA genes in B. flavum could remarkably increase the expression of DAHP synthetase; Co-expression of ppsA, pckA, aroG, pheA and tyrB of E. coli in B. flavum was a feasible approach to construct a strain for phenylalanine production. PMID:12532463

  9. Ionization state of L-phenylalanine at the air-water interface.

    PubMed

    Griffith, Elizabeth C; Vaida, Veronica

    2013-01-16

    The ionization state of organic molecules at the air-water interface and the related problem of the surface pH of water have significant consequences on the catalytic role of the surface in chemical reactions and are currently areas of intense research and controversy. In this work, infrared reflection-absorption spectroscopy (IRRAS) is used to identify changes in the ionization state of L-phenylalanine in the surface region versus the bulk aqueous solution. L-phenylalanine has the unique advantage of possessing two different hydrophilic groups, a carboxylic acid and an amine base, which can deprotonate and protonate respectively depending on the ionic environment they experience at the water surface. In this work, the polar group vibrations in the surface region are identified spectroscopically in varying bulk pH solutions, and are subsequently compared with the ionization state of the polar groups of molecules residing in the bulk environment. The polar groups of L-phenylalanine at the surface transition to their deprotonated state at bulk pH values lower than the molecules residing in the bulk, indicating a decrease in their pK(a) at the surface, and implying an enhanced hydroxide ion concentration in the surface region relative to the bulk.

  10. Combination of aerobic exercise and an arginine, alanine, and phenylalanine mixture increases fat mobilization and ketone body synthesis.

    PubMed

    Ueda, Keisuke; Sanbongi, Chiaki; Takai, Shoko; Ikegami, Shuji; Fujita, Satoshi

    2017-07-01

    During exercise, blood levels of several hormones increase acutely. We hypothesized that consumption of a specific combination of amino acids (arginine, alanine, and phenylalanine; A-mix) may be involved in secretion of glucagon, and when combined with exercise may promote fat catabolism. Ten healthy male volunteers were randomized in a crossover study to ingest either A-mix (3 g/dose) or placebo (3 g of dextrin/dose). Thirty minutes after ingesting, each condition subsequently performed workload trials on a cycle ergometer at 50% of maximal oxygen consumption for 1 h. After oral intake of A-mix, the concentrations of plasma ketone bodies and adrenalin during and post-exercise were significantly increased. The area under the curve for glycerol and glucagon was significantly increased in the post-exercise by A-mix administration. These results suggest that pre-exercise ingestion of A-mix causes a shift of energy source from carbohydrate to fat combustion by increasing secretion of adrenalin and glucagon.

  11. L-phenylalanine binding and domain organization in human phenylalanine hydroxylase: a differential scanning calorimetry study.

    PubMed

    Thórólfsson, Matthías; Ibarra-Molero, Beatriz; Fojan, Peter; Petersen, Steffen B; Sanchez-Ruiz, Jose M; Martínez, Aurora

    2002-06-18

    Human phenylalanine hydroxylase (hPAH) is a tetrameric enzyme that catalyzes the hydroxylation of L-phenylalanine (L-Phe) to L-tyrosine; a dysfunction of this enzyme causes phenylketonuria. Each subunit in hPAH contains an N-terminal regulatory domain (Ser2-Ser110), a catalytic domain (Asp112-Arg410), and an oligomerization domain (Ser411-Lys452) including dimerization and tetramerization motifs. Two partially overlapping transitions are seen in differential scanning calorimetry (DSC) thermograms for wild-type hPAH in 0.1 M Na-Hepes buffer, 0.1 M NaCl, pH 7.0. Although these transitions are irreversible, studies on their scan-rate dependence support that the equilibrium thermodynamics analysis is permissible in this case. Comparison with the DSC thermograms for truncated forms of the enzyme, studies on the protein and L-Phe concentration effects on the transitions, and structure-energetic calculations based on a modeled structure support that the thermal denaturation of hPAH occurs in three stages: (i) unfolding of the four regulatory domains, which is responsible for the low-temperature calorimetric transition; (ii) unfolding of two (out of the four) catalytic domains, which is responsible for the high-temperature transition; and (iii) irreversible protein denaturation, which is likely responsible for the observed exothermic distortion in the high-temperature side of the high-temperature transition. Stages 1 and 2 do not appear to be two-state processes. We present an approach to the analysis of ligand effects on DSC transition temperatures, which is based on the general binding polynomial formalism and is not restricted to two-state transitions. Application of this approach to the L-Phe effect on the DSC thermograms for hPAH suggests that (i) there are no binding sites for L-Phe in the regulatory domains; therefore, contrary to the common belief, the activation of PAH by L-Phe seems to be the result of its homotropic cooperative binding to the active sites. (ii

  12. Infrared Spectra of the 1-Chloromethyl-1-methylallyl and 1-Chloromethyl-2-methylallyl Radicals Isolated in Solid para-Hydrogen.

    PubMed

    Amicangelo, Jay C; Lee, Yuan-Pern

    2017-11-22

    The reaction of chlorine atoms (Cl) with isoprene (2-methyl-1,3-butadiene, C 5 H 8 ) in solid para-hydrogen (p-H 2 ) matrices at 3.2 K was studied using infrared (IR) spectroscopy. Mixtures of C 5 H 8 and Cl 2 were codeposited in p-H 2 at 3.2 K, followed by irradiation with ultraviolet light at 365 nm to induce the photodissociation of Cl 2 and the subsequent reaction of the Cl atoms with C 5 H 8 . Upon 365 nm photolysis, a multitude of new lines appeared in the IR spectrum, and, based on the secondary photolysis behavior, it was determined that the majority of the new lines belong to two distinct chemical species, designated as set A (intense lines at 1237.9, 807.8, and 605.6/608.2 cm -1 , and several other weaker lines) and set B (intense lines at 942.4, 1257.7, 796.7/798.5, 667.9, and 569.7 cm -1 , and several other weaker lines). Quantum-chemical calculations were performed at the B3PW91/6-311++G(2d,2p) level for ·C 5 H 7 and the four possible isomers of the ·C 5 H 8 Cl radicals, produced from the addition of the Cl atom to the four distinct sites of carbon atoms in C 5 H 8 , to determine the relative energetics and predict IR spectra for each radical. The newly observed lines of sets A and B are assigned to the 1-chloromethyl-2-methylallyl radical (addition to carbon 4) and the 1-chloromethyl-1-methylallyl radical (addition to carbon 1) according to comparison with predicted IR spectra of possible products. The 1-chloromethyl-2-methylallyl radical and 1-chloromethyl-1-methylallyl radicals were predicted to be the most stable, with the latter ∼8 kJ mol -1 lower in energy than the former. The ratio of the 1-chloromethyl-1-methylallyl to the 1-chloromethyl-2-methylallyl radicals is estimated to be (1.2 ± 0.5):1.0, indicating that the two radicals are produced in approximately equal amounts. The exclusive production of the radicals involving the addition of the Cl atom to the two terminal carbons of isoprene is analogous to what was previously observed for

  13. Highly efficient drug delivery nanosystem via L-phenylalanine triggering based on supramolecular polymer micelles.

    PubMed

    Dong, Haiqing; Li, Yongyong; Wen, Huiyun; Xu, Meng; Liu, Lijian; Li, Zhuoquan; Guo, Fangfang; Shi, Donglu

    2011-03-16

    An intelligent drug delivery nanosystem has been developed based on biodegradable supramolecular polymer micelles (SMPMs). The drug release can be triggered from SMPMs responsively by a bioactive agent, L-phenylalanine in a controlled fashion. The SMPMs are constructed from ethylcellulose-graft-poly(ε-caprolactone) (EC-g-PCL) and α-cyclodextrin (α-CD) derivate via host-guest and hydrophobic interactions. It has been found that these SMPMs have disassembled rapidly in response to an additional L-phenylalanine, due to great affinity discrepancy to α-CD between L-phenylalanine and PCL. Experiments have been carried out on trigger-controlled in vitro drug release of the SMPMs loaded with a model porphyrin based photosensitizer THPP. The result shows that the SMPMs released over 85% THPP in 6 h, which is two orders magnitudes faster than that of control. Also investigated is the photodynamic therapy (PDT) of THPP-loaded SMPMs with and without L-phenylalanine on MCF-7 carcinoma cell line. An effective trigger-concentration dependent lethal effect has been found showing promise in clinical photodynamic therapy. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Calcium Sensing Receptors Mediate Local Inhibitory Reflexes Evoked by L-Phenylalanine in Guinea Pig Jejunum.

    PubMed

    Gwynne, Rachel M; Ly, Kenny D K N; Parry, Laura J; Bornstein, Joel C

    2017-01-01

    Amino acids applied to the mucosa evoke inhibitory reflexes in guinea-pig jejunum, but the receptors involved in sensory transduction are still unclear. One promising candidate is the extracellular calcium sensing receptor (CaSR), which is expressed by mucosal enteroendocrine cells and is preferentially activated by aromatic L-amino acids. We tested this by applying various amino acids to the mucosa and recording the resulting inhibitory junction potentials (IJPs) in nearby circular smooth muscle via intracellular recording. The CaSR is stereospecific and L-Phenylalanine evoked a significantly larger response than D-Phenylalanine when both were applied to the same site. The same pattern was seen with L- and D-Tryptophan, another aromatic amino acid. The CaSR is preferentially activated by aromatic amino acids and responses to L-Leucine and L-Lysine were significantly lower than those to L-Phenylalanine applied to the same site. Responses to L-Phenylalanine were dose-dependently suppressed by blockade of the CaSR with NPS2143, a CaSR antagonist, and mimicked by mucosal application of cinacalcet, a CaSR agonist. Responses to cinacalcet had similar pharmacology to that of responses to L-Phenylalanine, in that each requires both P2 purinoreceptors and 5-HT receptors. L-Glutamate evoked IJPs similar to those produced by L-Phenylalanine and these were depressed by blockade of P2 receptors and 5-HT 3 plus 5-HT 4 receptors, but NPS2143 was ineffective. The AMPA receptor antagonists DNQX (10 μM) and CNQX (10 μM) reduced IJPs evoked by L-Glutamate by 88 and 79% respectively, but neither BAY367260 (mGluR5 antagonist) nor 2APV (NMDA antagonist) affected IJPs evoked by L-Glutamate. We conclude that local inhibitory reflexes evoked by aromatic L-amino acids in guinea pig jejunum involve activation of CaSRs which triggers release of ATP and 5-HT from the mucosa. L-Glutamate also evokes inhibitory reflexes, via a pathway that does not involve CaSRs. It is likely there are

  15. Improving the Production of L-Phenylalanine by Identifying Key Enzymes Through Multi-Enzyme Reaction System in Vitro

    PubMed Central

    Ding, Dongqin; Liu, Yongfei; Xu, Yiran; Zheng, Ping; Li, Haixing; Zhang, Dawei; Sun, Jibin

    2016-01-01

    L-Phenylalanine (L-Phe) is an important amino acid used in both food and medicinal applications. We developed an in vitro system that allowed a direct, quantitative investigation of phenylalanine biosynthesis in E. coli. Here, the absolute concentrations of six enzymes (AroK, AroL, AroA, AroC, PheA and TyrB) involved in the shikimate (SHIK) pathway were determined by a quantitative proteomics approach and in vitro enzyme titration experiments. The reconstitution of an in vitro reaction system for these six enzymes was established and their effects on the phenylalanine production were tested. The results showed that the yield of phenylalanine increased 3.0 and 2.1 times when the concentrations of shikimate kinase (AroL) and 5-enolpyruvoyl shikimate 3-phosphate (EPSP) synthase (AroA) were increased 2.5 times. Consistent results were obtained from in vivo via the overexpression of AroA in a phenylalanine-producing strain, and the titer of phenylalanine reached 62.47 g/l after 48 h cultivation in a 5-liter jar fermentor. Our quantitative findings provide a practical method to detect the potential bottleneck in a specific metabolic pathway to determine which gene products should be targeted to improve the yield of the desired product. PMID:27558633

  16. [Microbial synthesis of deuterium labelled L-phenylalanine with different levels of isotopic enrichment by facultative methylotrophic bacterium Brevibacterium methylicum with RMP assimilation of carbon].

    PubMed

    Mosin, O V; Shvets, V I; Skladnev, D A; Ignatov, I

    2014-01-01

    The preparative microbial synthesis of amino acids labelled with stable isotopes, including deuterium ( 2 H), suitable for biomedical applications by methylotrophic bacteria was studied using L-phenylalanine as example. This amino acid is secreted by Gram-negative aerobic facultative methylotrophic bacteria Brevibacterium methylicum, assimilating methanol via ribulose-5-monophosphate (RMP) cycle of assimilation of carbon, The data on adaptation of L-phenylalanine secreted by methylotrophic bacterium В. methylicum to the maximal concentration of deuterium in the growth medium with 98% 2 Н 2 O and 2% [ 2 Н]methanol, and biosynthesis of deuterium labelled L-phenylalanine With different levels of enrichment are presented. The strain was adapted by means of plating initial cells on firm (2% agarose) minimal growth media with an increasing gradient of 2 Н 2 O concentration from 0; 24.5; 49.0; 73.5 up to 98% 2 Н 2 O followed by subsequent selection of separate colonies stable to the action of 2 Н 2 O. These colonies were capable to produce L-phenylalanine. L-phenylalanine was extracted from growth medium by extraction with isopropanol with the subsequent crystallization in ethanol (output 0.65 g/l). The developed method of microbial synthesis allows to obtain deuterium labelled L-phenylalanine with different levels of isotopic enrichment, depending on concentration of 2 Н 2 O in growth media, from 17% (on growth medium with 24,5% 2 Н 2 O) up to 75% (on growth medium with 98% 2 Н 2 O) of deuterium in the molecule that is confirmed with the data of the electron impact (EI) mass- spectrometry analysis of methyl ethers of N-dimethylamino(naphthalene)-5-sulfochloride (dansyl) phenylalanine in these experimental conditions.

  17. Oxidation of L-phenylalanine by diperiodatoargentate(III) in aqueous alkaline medium. A Mechanistic approach

    NASA Astrophysics Data System (ADS)

    Lamani, S. D.; Veeresh, T. M.; Nandibewoor, S. T.

    2009-12-01

    The kinetics of oxidation of L-phenylalanine (L-Phe) by diperiodatoargentate(III) (DPA) in alkaline medium at a constant ionic strength of 0.25 mol/dm-3 has been studied spectrophotometrically. The reaction between DPA and L-phenylalanine in alkaline medium exhibits 1: 1 stoichiometry (L-phenylalanine: DPA). The reaction shows first order in [DPA] and has less than unit order dependence each in both [L-Phe] and [Alkali] and retarding effect of [IO{4/-}] under the reaction conditions. The active species of DPA is understood to be as monoperiodatoargentate(III) (MPA). The reaction is shown to proceed via a MPA-L-Phe complex, which decomposes in a rate-determining step to give intermediates followed by a fast step to give the products. The products were identified by spot and spectroscopic studies. The reaction constants involved in the different steps of the mechanisms were calculated. The activation parameters with respect to slow step of the mechanism were computed and discussed. The thermodynamic quantities were also determined for the reaction.

  18. Syntheses of halogen derivatives of L-tryptophan, L-tyrosine and L-phenylalanine labeled with hydrogen isotopes.

    PubMed

    Pająk, Małgorzata; Pałka, Katarzyna; Winnicka, Elżbieta; Kańska, Marianna

    2016-01-01

    Halogenated, labeled with tritium and doubly with deuterium and tritium, derivatives of L-tryptophan, i.e. 5'-bromo-[2-(3)H]-, 5'-bromo-[2-(2)H/(3)H]-, 5'-fluoro-[2-(3)H]-5'-fluoro-[2-(2)H/(3)H]-, 6'-fluoro-[2-(3)H]-, 6'-fluoro-[2-(2)H/(3)H]-L-tryptophan, as well as, L-tyrosine, i.e. 3'-fluoro-[2-(3)H]-, 3'-fluoro-[2-(2)H/(3)H]-, 3'-chloro-[2-(3)H]-, and 3'-chloro-[2-(2)H/(3)H]-L-tyrosine, and also L-phenylalanine, i.e. 2'-fluoro-[(3S)-(3)H]-, 2'-fluoro-[(3S)-(2)H/(3) H]-, 2'-chloro-[(3S)-(3)H]-, 2'-chloro-[(3S)-(2)H/(3)H]-, 4'-chloro-[(3S)-(3)H]-, and 4'-chloro-[(3S)-(2)H/(3)H]-L-phenylalanine were synthesized using enzymatic methods. Isotopomers of L-tryptophan were synthesized by coupling of halogenated indoles with S-methyl-L-cysteine carried out in deuteriated or tritiated incubation media. Labeled halogenated derivatives of L-tyrosine were obtained by the enzymatically supported exchange between halogenated L-tyrosine and isotopic water. Labeled halogenated isotopologues of L-Phe were synthesized by the enzymatic addition of ammonia to halogenated cinnamic acid. As a source of hydrogen tritiated water (HTO) and heavy water (D2O) with addition of HTO were used. Copyright © 2015 John Wiley & Sons, Ltd.

  19. Improvement of constraint-based flux estimation during L-phenylalanine production with Escherichia coli using targeted knock-out mutants.

    PubMed

    Weiner, Michael; Tröndle, Julia; Albermann, Christoph; Sprenger, Georg A; Weuster-Botz, Dirk

    2014-07-01

    Fed-batch production of the aromatic amino acid L-phenylalanine was studied with recombinant Escherichia coli strains on a 15 L-scale using glycerol as carbon source. Flux Variability Analysis (FVA) was applied for intracellular flux estimation to obtain an insight into intracellular flux distribution during L-phenylalanine production. Variability analysis revealed great flux uncertainties in the central carbon metabolism, especially concerning malate consumption. Due to these results two recombinant strains were genetically engineered differing in the ability of malate degradation and anaplerotic reactions (E. coli FUS4.11 ΔmaeA pF81kan and E. coli FUS4.11 ΔmaeA ΔmaeB pF81kan). Applying these malic enzyme knock-out mutants in the standardized L-phenylalanine production process resulted in almost identical process performances (e.g., L-phenylalanine concentration, production rate and byproduct formation). This clearly highlighted great redundancies in central metabolism in E. coli. Uncertainties of intracellular flux estimations by constraint-based analyses during fed-batch production of L-phenylalanine were drastically reduced by application of the malic enzyme knock-out mutants. © 2014 Wiley Periodicals, Inc.

  20. Design of a recombinant Escherichia coli for producing L-phenylalanine from glycerol.

    PubMed

    Thongchuang, Mayura; Pongsawasdi, Piamsook; Chisti, Yusuf; Packdibamrung, Kanoktip

    2012-10-01

    A recombinant Escherichia coli was engineered to produce the commercially important amino acid L-phenylalanine (L-Phe) using glycerol as the carbon source. Compared to the conventionally used glucose and sucrose, glycerol is a less expensive carbon source. As phenylalanine dehydrogenase (PheDH) activity is involved in the last step of L-Phe synthesis in E. coli, a phenylalanine dehydrogenase gene (phedh) from the thermotolerant Bacillus lentus was cloned into pRSFDuet-1 (pPheDH) and expressed in E. coli BL21(DE3). The resulting clone had a limited ability to produce L-Phe from glycerol, possibly because of a poor glycerol uptake by the cell, or an inability to excrete L-Phe, or both. Therefore, yddG gene encoding an aromatic amino acid exporter and glpF gene encoding a glycerol transport facilitator were coexpressed with the phedh in a reengineered E. coli. In a glycerol medium, the maximum L-Phe production rates of the clones pPY (phedh and yddG genes) and pPYF (phedh, yddG and glpF genes) were 1.4- and 1.8-fold higher than the maximum production rate of the pPheDH clone. The better producing pPYF clone was further evaluated in a 5 l stirred-tank fermenter (37 °C, an aeration rate of 1 vvm, an agitation speed of 400 rpm). In the fermenter, the maximum concentration of L-Phe (366 mg/l) was achieved in a much shorter period compared to in the shake flasks. In the latter, the highest titer of L-Phe was only 76 % of the maximum value attained in the fermenter.

  1. Growth and characterization of novel organic 3-Hydroxy Benzaldehyde-N-methyl 4 Stilbazolium Tosylate crystals for NLO applications.

    PubMed

    Jagannathan, K; Umarani, P; Ratchagar, V; Ramesh, V; Kalainathan, S

    2016-01-15

    The 3-Hydroxy Benzaldehyde-N-methyl 4-Stilbazolium Tosylate (3- HBST) is a new organic NLO crystal and it is a new derivative in stilbazolium tosylate family. In this work we have synthesized 3-HBST and the single crystal was grown by conventional slow cooling method. The structure and lattice parameters of the grown crystal were determined by the single crystal X-ray diffraction (XRD) technique and it is exhibiting good crystalline nature which is observed from the powder XRD. In order to check the crystalline quality the rocking curve was recorded using multi crystal X-ray diffractometer. The functional groups were identified from both FTIR and NMR spectral analyses. The π-π* and n-π* optical transition energy levels were estimated from the absorption peaks. The NLO property was confirmed by measuring relative SHG efficiency by Kurtz powder test; it shows 24 times higher SHG efficiency than that of urea. In order to test the mechanical stability the Vickers and Knoop micro hardness measurement were carried out and found that the micro hardness number decreases with increasing load. The melting point was determined from Differential Scanning Colorimetry (DSC). Copyright © 2015 Elsevier B.V. All rights reserved.

  2. One-Pot Enzymatic Synthesis of D-Arylalanines Using Phenylalanine Ammonia Lyase and L-Amino Acid Deaminase.

    PubMed

    Zhu, Longbao; Feng, Guoqiang; Ge, Fei; Song, Ping; Wang, Taotao; Liu, Yi; Tao, Yugui; Zhou, Zhemin

    2018-06-08

    The phenylalanine ammonia-lyase (AvPAL) from Anabaena variabilis catalyzes the amination of substituent trans-cinnamic acid (t-CA) to produce racemic D,L-enantiomer arylalanine mixture owing to its low stereoselectivity. To produce high optically pure D-arylalanine, a modified AvPAL with high D-selectivity is expected. Based on the analyses of catalytic mechanism and structure, the Asn347 residue in the active site was proposed to control stereoselectivity. Therefore, Asn347 was mutated to construct mutant AvPAL-N347A, the stereoselectivity of AvPAL-N347A for D-enantiomer arylalanine was 2.3-fold higher than that of wild-type AvPAL (WtPAL). Furthermore, the residual L-enantiomer product in reaction solution could be converted into the D-enantiomer product through stereoselective oxidation by PmLAAD and nonselective reduction by reducing agent NH 3 BH 3 . At optimal conditions, the conversion rate of t-CA and optical purity (enantiomeric excess (ee D )) of D-phenylalanine reached 82% and exceeded 99%, respectively. The two enzymes displayed activity toward a broad range of substrate and could be used to efficiently synthesize D-arylalanine with different groups on the phenyl ring. Among these D-arylalanines, the yield of m-nitro-D-phenylalanine was highest and reached 96%, and the ee D exceeded 99%. This one-pot synthesis using AvPAL and PmLAAD has prospects for industrial application.

  3. Intramolecular interactions of L-phenylalanine: Valence ionization spectra and orbital momentum distributions of its fragment molecules.

    PubMed

    Ganesan, Aravindhan; Wang, Feng; Falzon, Chantal

    2011-02-01

    Intramolecular interactions between fragments of L-phenylalanine, i.e., phenyl and alaninyl, have been investigated using dual space analysis (DSA) quantum mechanically. Valence space photoelectron spectra (PES), orbital energy topology and correlation diagram, as well as orbital momentum distributions (MDs) of L-phenylalanine, benzene and L-alanine are studied using density functional theory methods. While fully resolved experimental PES of L-phenylalanine is not yet available, our simulated PES reproduces major features of the experimental measurement. For benzene, the simulated orbital MDs for 1e(1g) and 1a(2u) orbitals also agree well with those measured using electron momentum spectra. Our theoretical models are then applied to reveal intramolecular interactions of the species on an orbital base, using DSA. Valence orbitals of L-phenylalanine can be essentially deduced into contributions from its fragments such as phenyl and alaninyl as well as their interactions. The fragment orbitals inherit properties of their parent species in energy and shape (ie., MDs). Phenylalanine orbitals show strong bonding in the energy range of 14-20 eV, rather than outside of this region. This study presents a competent orbital based fragments-in-molecules picture in the valence space, which supports the fragment molecular orbital picture and building block principle in valence space. The optimized structures of the molecules are represented using the recently developed interactive 3D-PDF technique. Copyright © 2010 Wiley Periodicals, Inc.

  4. Metabolic engineering of Escherichia coli for production of 2-Phenylethylacetate from L-phenylalanine.

    PubMed

    Guo, Daoyi; Zhang, Lihua; Pan, Hong; Li, Xun

    2017-08-01

    In order to meet the need of consumer preferences for natural flavor compounds, microbial synthesis method has become a very attractive alternative to the chemical production. The 2-phenylethanol (2-PE) and its ester 2-phenylethylacetate (2-PEAc) are two extremely important flavor compounds with a rose-like odor. In recent years, Escherichia coli and yeast have been metabolically engineered to produce 2-PE. However, a metabolic engineering approach for 2-PEAc production is rare. Here, we designed and expressed a 2-PEAc biosynthetic pathway in E. coli. This pathway comprised four steps: aminotransferase (ARO8) for transamination of L-phenylalanine to phenylpyruvate, 2-keto acid decarboxylase KDC for the decarboxylation of the phenylpyruvate to phenylacetaldehyde, aldehyde reductase YjgB for the reduction of phenylacetaldehyde to 2-PE, alcohol acetyltransferase ATF1 for the esterification of 2-PE to 2-PEAc. Using the engineered E. coli strain for shake flasks cultivation with 1 g/L L-phenylalanine, we achieved co-production of 268 mg/L 2-PEAc and 277 mg/L 2-PE. Our results suggest that approximately 65% of L-phenylalanine was utilized toward 2-PEAc and 2-PE biosynthesis and thus demonstrate potential industrial applicability of this microbial platform. © 2017 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

  5. Nucleation kinetics from metastable zone widths for sonocrystallization of l-phenylalanine.

    PubMed

    Hazi Mastan, T; Lenka, Maheswata; Sarkar, Debasis

    2017-05-01

    This study investigates the effect of ultrasound on metastable zone width (MSZW) during crystallization of l-phenylalanine from aqueous solution. The solubility of l-phenylalanine in water was measured gravimetrically in the temperature range of 293.15-333.15K. The MSZW was measured by conventional polythermal method for four different cooling rates at five different saturation temperatures in absence and presence of ultrasound. The MSZW increased with increase in cooling rates and decreased with increase in saturation temperature. The application of ultrasound considerably reduced the MSZW for all the experiments. The obtained MSZW data are analysed using four different approaches to calculate various nucleation parameters. In presence of ultrasound, the apparent nucleation order decreased and nucleation rate constant increased significantly. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Sodium sulfite pH-buffering effect for improved xylose-phenylalanine conversion to N-(1-deoxy-d-xylulos-1-yl)-phenylalanine during an aqueous Maillard reaction.

    PubMed

    Cui, Heping; Duhoranimana, Emmanuel; Karangwa, Eric; Jia, Chengsheng; Zhang, Xiaoming

    2018-04-25

    The yield of the Maillard reaction intermediate (MRI), prepared in aqueous medium, is usually unsatisfactory. However, the addition of sodium sulfite could improve the conversion of xylose-phenylalanine (Xyl-Phe) to the MRI (N-(1-deoxy-d-xylulos-1-yl)-phenylalanine) in aqueous medium. Sodium sulfite (Na 2 SO 3 ) showed a significant pH-buffering effect during the Maillard reaction, which accounted for its facilitation of the N-(1-deoxy-d-xylulos-1-yl)-phenylalanine yield. The results revealed that the pH could be maintained at a relatively high level (above 7.0) for an optimized pH-buffering effect when Na 2 SO 3 (4.0%) was added before the reaction of Xyl-Phe. Thus, the conversion of Xyl-Phe to N-(1-deoxy-d-xylulos-1-yl)-phenylalanine increased from 47.23% to 74.86%. Furthermore, the addition moment of Na 2 SO 3 and corresponding solution pH were crucial factors in regulating the pH-buffering effect of Na 2 SO 3 on N-(1-deoxy-d-xylulos-1-yl)-phenylalanine yield. Based on the pH-buffering effect of Na 2 SO 3 and maintaining the optimal pH 7.4 relatively stable, the conversion of Xyl-Phe to N-(1-deoxy-d-xylulos-1-yl)-phenylalanine was successfully improved. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Novel ketone diet enhances physical and cognitive performance

    PubMed Central

    Murray, Andrew J.; Knight, Nicholas S.; Cole, Mark A.; Cochlin, Lowri E.; Carter, Emma; Tchabanenko, Kirill; Pichulik, Tica; Gulston, Melanie K.; Atherton, Helen J.; Schroeder, Marie A.; Deacon, Robert M. J.; Kashiwaya, Yoshihiro; King, M. Todd; Pawlosky, Robert; Rawlins, J. Nicholas P.; Tyler, Damian J.; Griffin, Julian L.; Robertson, Jeremy; Veech, Richard L.; Clarke, Kieran

    2016-01-01

    Ketone bodies are the most energy-efficient fuel and yield more ATP per mole of substrate than pyruvate and increase the free energy released from ATP hydrolysis. Elevation of circulating ketones via high-fat, low-carbohydrate diets has been used for the treatment of drug-refractory epilepsy and for neurodegenerative diseases, such as Parkinson’s disease. Ketones may also be beneficial for muscle and brain in times of stress, such as endurance exercise. The challenge has been to raise circulating ketone levels by using a palatable diet without altering lipid levels. We found that blood ketone levels can be increased and cholesterol and triglycerides decreased by feeding rats a novel ketone ester diet: chow that is supplemented with (R)-3-hydroxybutyl (R)-3-hydroxybutyrate as 30% of calories. For 5 d, rats on the ketone diet ran 32% further on a treadmill than did control rats that ate an isocaloric diet that was supplemented with either corn starch or palm oil (P < 0.05). Ketone-fed rats completed an 8-arm radial maze test 38% faster than did those on the other diets, making more correct decisions before making a mistake (P < 0.05). Isolated, perfused hearts from rats that were fed the ketone diet had greater free energy available from ATP hydrolysis during increased work than did hearts from rats on the other diets as shown by using [31P]-NMR spectroscopy. The novel ketone diet, therefore, improved physical performance and cognitive function in rats, and its energy-sparing properties suggest that it may help to treat a range of human conditions with metabolic abnormalities.—Murray, A. J., Knight, N. S., Cole, M. A., Cochlin, L. E., Carter, E., Tchabanenko, K., Pichulik, T., Gulston, M. K., Atherton, H. J., Schroeder, M. A., Deacon, R. M. J., Kashiwaya, Y., King, M. T., Pawlosky, R., Rawlins, J. N. P., Tyler, D. J., Griffin, J. L., Robertson, J., Veech, R. L., Clarke, K. Novel ketone diet enhances physical and cognitive performance. PMID:27528626

  8. Global Metabolic Profiling of Plasma Shows that Three-Year Mild-Caloric Restriction Lessens an Age-Related Increase in Sphingomyelin and Reduces L-leucine and L-phenylalanine in Overweight and Obese Subjects.

    PubMed

    Kim, Minjoo; Lee, Sang-Hyun; Lee, Jong Ho

    2016-12-01

    The effect of weight loss from long-term, mild-calorie diets (MCD) on plasma metabolites is unknown. This study was to examine whether MCD-induced weight reduction caused changes in the extended plasma metabolites. Overweight and obese subjects aged 40-59 years consumed a MCD (approximately 100 kcal/day deficit, n =47) or a weight-maintenance diet (control, n =47) in a randomized, controlled design with a three-year clinical intervention period and plasma samples were analyzed by using UPLC-LTQ-Orbitrap mass spectrometry. The three-year MCD intervention resulted in weight loss (-8.87%) and significant decreases in HOMA-IR and TG. The three-year follow-up of the MCD group showed reductions in the following 13 metabolites: L-leucine; L-phenylalanine; 9 lysoPCs; PC (18:0/20:4); and SM (d18:0/16:1). The three-year MCD group follow-up identified increases in palmitic amide, oleamide, and PC (18:2/18:2). Considering the age-related alterations in the identified metabolites, the MCD group showed a greater decrease in L-leucine, L-phenylalanine, and SM (d18:0/16:1) compared with those of the control group. Overall, the change (Δ) in BMI positively correlated with the ΔTG, ΔHOMA-IR, ΔL-leucine, and ΔSM (d18:0/16:1). The ΔHOMA-IR positively correlated with ΔTG, ΔL-leucine, ΔL-phenylalanine, and ΔSM (d18:0/16:1). The weight loss resulting from three-year mild-caloric restriction lessens the age-related increase in SM and reduces L-leucine and L-phenylalanine in overweight and obese subjects. These changes were coupled with improved insulin resistance (ClinicalTrials.gov: NCT02081898).

  9. The thermodynamic characteristics of solution of L-α-histidine and L-α-phenylalanine in water at 273 373 K

    NASA Astrophysics Data System (ADS)

    Kustov, A. V.; Korolev, V. P.

    2008-11-01

    The solubility of L-phenylalanine and L-histidine in water at 298.15 and 318.15 K and the heat effects of solution of the amino acids at 328.15 K were determined. These results and the data obtained earlier were used to calculate all the standard thermodynamic functions of solution of the amino acids and the solubilities of L-phenylalanine and L-histidine over the temperature range 273 373 K. The selection of the form of the Δsol H o = f( T) dependence had a negligible effect on the free energies of solution and solubilities of the amino acids. This selection primarily influenced the entropy and heat capacity characteristics of the process.

  10. The in vivo anti-fibrotic function of calcium sensitive receptor (CaSR) modulating poly(p-dioxanone-co-l-phenylalanine) prodrug.

    PubMed

    Wang, Bing; Wen, Aiping; Feng, Chengmin; Niu, Lijing; Xiao, Xin; Luo, Le; Shen, Chengyi; Zhu, Jiang; Lei, Jun; Zhang, Xiaoming

    2018-06-01

    In present study, the apoptosis induction and proliferation suppression effects of l-phenylalanine (l-Phe) on fibroblasts were confirmed. The action sites of l-Phe on fibroblasts suppression were deduced to be calcium sensitive receptor (CaSR) which could cause the release of endoplasmic reticulum (ER) Ca 2+ stores; disruption of intracellular Ca 2+ homeostasis triggers cell apoptosis via the ER or mitochondrial pathways. The down-regulation of CaSR were observed after the application of l-Phe, and the results those l-Phe triggered the increasing of intracellular Ca 2+ concentration and calcineurin expression, and then the apoptosis and increasing G1 fraction of fibroblasts have verified our deduction. Hence, l-Phe could be seen as a kind of anti-fibrotic drugs for the crucial participation of fibroblast in the occurrence of fibrosis. And then, poly(p-dioxanone-co-l-phenylalanine) (PDPA) which could prolong the in-vivo anti-fibrotic effect of l-Phe for the sustained release of l-Phe during its degradation could be treated as anti-fibrotic polymer prodrugs. Based on the above, the in vivo anti-fibrotic function of PDPA was evaluated in rabbit ear scarring, rat peritoneum lipopolysaccharide, and rat sidewall defect/cecum abrasion models. PDPA reduced skin scarring and suppressed peritoneal fibrosis and post operation adhesion as well as secretion of transforming growth factor-β1 in injured tissue. These results indicate that PDPA is an effective agent for preventing fibrosis following tissue injury. We have previously demonstrated that poly(p-dioxanone-co-l-phenylalanine) (PDPA) could induce apoptosis to fibroblast and deduced that the inhibitory effect comes from l-phenylalanine. In present study, the inhibition mechanism of l-phenylalanine on fibroblast proliferation was demonstrated. The calcium sensitive receptor (CaSR) was found to be the action site. The CaSR was downregulated after the application of l-phenylalanine, and then the ER Ca 2+ stores were released

  11. Radiosynthesis and biological evaluation of N-(2-[18F]fluoropropionyl)-3,4-dihydroxy-l-phenylalanine as a PET tracer for oncologic imaging.

    PubMed

    Tang, Caihua; Nie, Dahong; Tang, Ganghua; Gao, Siyuan; Liu, Shaoyu; Wen, Fuhua; Tang, Xiaolan

    2017-07-01

    Several 11 C and 18 F labeled 3,4-dihydroxy-l-phenylalanine (l-DOPA) analogues have been used for neurologic and oncologic diseases, especially for brain tumors and neuroendocrine tumors PET imaging. However, 18 F-labeled N-substituted l-DOPA analogues have not been reported so far. In the current study, radiosynthesis and biological evaluation of a new 18 F-labeled l-DOPA analogue, N-(2-[ 18 F]fluoropropionyl)-3,4-dihydroxy-l-phenylalanine ([ 18 F]FPDOPA) for tumor PET imaging are performed. The synthesis of [ 18 F]FPDOPA was via a two-step reaction sequence from 4-nitrophenyl-2-[ 18 F]fluoropropionate ([ 18 F]NFP). The biodistribution of [ 18 F]FPDOPA was determined in normal Kunming mice. In vitro competitive inhibition and protein incorporation experiments were performed with SPC-A-1 lung adenocarcinoma cell lines. PET/CT studies of [ 18 F]FPDOPA were conducted in C6 rat glioma and SPC-A-1 human lung adenocarcinoma and H460 human large cell lung cancer-bearing nude mice. [ 18 F]FPDOPA was prepared with a decay-corrected radiochemical yield of 28±5% and a specific activity of 50±15GBq/μmol (n=10) within 125min. In vitro cell experiments showed that [ 18 F]FPDOPA uptake in SPC-A-1 cells was primarily transported through Na + -independent system L, with Na + -dependent system B 0,+ and system ASC partly involved in it. Biodistribution data in mice showed that renal-bladder route was the main excretory system of [ 18 F]FPDOPA. PET imaging demonstrated intense accumulation of [ 18 F]FPDOPA in several tumor xenografts, with (8.50±0.40)%ID/g in C6 glioma, (6.30±0.12)%ID/g in SPC-A-1 lung adenocarcinoma, and (6.50±0.10)%ID/g in H460 large cell lung cancer, respectively. A novel N-substituted 18 F-labeled L-DOPA analogue [ 18 F]FPDOPA is synthesized and evaluated in vitro and in vivo. The results support that [ 18 F]FPDOPA seems to be a potential PET tracer for tumor imaging, especially be a better potential PET tracer than [ 18 F]fluoro-2-deoxy-d-glucose ([ 18 F

  12. Synthesis and biological evaluation of N-(carbobenzyloxy)-l-phenylalanine and N-(carbobenzyloxy)-l-aspartic acid-β-benzyl ester derivatives as potent topoisomerase IIα inhibitors.

    PubMed

    Han, Xiaoyan; Zhong, Yifan; Zhou, Guan; Qi, Hui; Li, Shengbin; Ding, Qiang; Liu, Zhenming; Song, Yali; Qiao, Xiaoqiang

    2017-06-15

    A new series of thirteen N-(carbobenzyloxy)-l-phenylalanine and N-(carbobenzyloxy)-l-aspartic acid-β-benzyl ester compounds were synthesized and evaluated for antiproliferative activity against four different human cancer cell lines: cervical cancer (HeLa), lung cancer (A549), gastric cancer (MGC-803) and breast cancer (MCF-7) as well as topoisomerase I and IIα inhibitory activity. Compounds (5a, 5b, 5e, 8a, 8b) showed significant antiproliferative activity with low IC 50 values against the four cancer cell lines. Equally, compounds 5a, 5b, 5e, 5f, 8a, 8d, 8e and 8f showed topoisomerase IIα inhibitory activity at 100μM with 5b, 5e, 8f exhibiting potential topoisomerase IIα inhibitory activity compared to positive control at 100μM and 20μM, respectively. Conversely compounds 5e, 5f, 5g and 8a showed weaker topoisomerase I inhibitory activity compared to positive control at 100μM. Compound 5b exhibited the most potent topoisomerase IIα inhibitory activity at low concentration and better antiproliferative activity against the four human cancer cell lines. The molecular interactions between compounds 5a-5g, 8a-8f and the topoisomerase IIα (PDB ID: 1ZXM) were further investigated through molecular docking. The results indicated that these compounds could serve as promising leads for further optimization as novel antitumor agents. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Sensitive, site-specific, and stable vibrational probe of local protein environments: 4-azidomethyl-L-phenylalanine.

    PubMed

    Bazewicz, Christopher G; Liskov, Melanie T; Hines, Kevin J; Brewer, Scott H

    2013-08-01

    We have synthesized the unnatural amino acid (UAA), 4-azidomethyl-L-phenylalanine (pN₃CH₂Phe), to serve as an effective vibrational reporter of local protein environments. The position, extinction coefficient, and sensitivity to local environment of the azide asymmetric stretch vibration of pN₃CH₂Phe are compared to the vibrational reporters: 4-cyano-L-phenylalanine (pCNPhe) and 4-azido-L-phenylalanine (pN₃Phe). This UAA was genetically incorporated in a site-specific manner utilizing an engineered, orthogonal aminoacyl-tRNA synthetase in response to an amber codon with high efficiency and fidelity into two distinct sites in superfolder green fluorescent protein (sfGFP). This allowed for the dependence of the azide asymmetric stretch vibration of pN₃CH₂Phe to different protein environments to be measured. The photostability of pN₃CH₂Phe was also measured relative to the photoreactive UAA, pN₃Phe.

  14. Structural study, NCA, FT-IR, FT-Raman spectral investigations, NBO analysis, thermodynamic functions of N-acetyl-l-phenylalanine.

    PubMed

    Raja, B; Balachandran, V; Revathi, B

    2015-03-05

    The FT-IR and FT-Raman spectra of N-acetyl-l-phenylalanine were recorded and analyzed. Natural bond orbital analysis has been carried out for various intramolecular interactions that are responsible for the stabilization of the molecule. HOMO-LUMO energy gap has been computed with the help of density functional theory. The statistical thermodynamic functions (heat capacity, entropy, vibrational partition function and Gibbs energy) were obtained for the range of temperature 100-1000K. The polarizability, first hyperpolarizability, anisotropy polarizability invariant has been computed using quantum chemical calculations. The infrared and Raman spectra were also predicted from the calculated intensities. Comparison of the experimental and theoretical spectra values provides important information about the ability of the computational method to describe the vibrational modes. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Catalyzed and Electrocatalyzed Oxidation of l-Tyrosine and l-Phenylalanine to Dopachrome by Nanozymes.

    PubMed

    Hou, Jianwen; Vázquez-González, Margarita; Fadeev, Michael; Liu, Xia; Lavi, Ronit; Willner, Itamar

    2018-06-13

    Catalyzed oxygen insertion into C-H bonds represents a continuous challenge in chemistry. Particularly, driving this process at ambient temperature and aqueous media represents a "holy grail" in catalysis. We report on the catalyzed cascade transformations of l-tyrosine or l-phenylalanine to dopachrome in the presence of l-ascorbic acid/H 2 O 2 as oxidizing mixture and CuFe-Prussian Blue-like nanoparticles, Fe 3 O 4 nanoparticles or Au nanoparticles as catalysts. The process involves the primary transformation of l-tyrosine to l-DOPA that is further oxidized to dopachrome. The transformation of l-phenylalanine to dopachrome in the presence of CuFe-Prussian Blue-like nanoparticles and l-ascorbic acid/H 2 O 2 involves in the first step the formation of l-tyrosine and, subsequently, the operation of the catalytic oxidation cascade of l-tyrosine to l-DOPA and dopachrome. Electron spin resonance experiments demonstrate that ascorbate radicals and hydroxyl radicals play cooperative functions in driving the different oxygen-insertion processes. In addition, the aerobic elecrocatalyzed oxidation of l-tyrosine to dopachrome in the presence of naphthoquinone-modified Fe 3 O 4 nanoparticles and l-ascorbic acid is demonstrated. In this system, magnetic-field attraction of the naphthoquinone-modified Fe 3 O 4 nanoparticles onto the electrode allows the quinone-mediated electrocatalyzed reduction of O 2 to H 2 O 2 (bias potential -0.5 V vs SCE). The electrogenerated H 2 O 2 is then utilized to promote the transformation of l-tyrosine to dopachrome in the presence of l-ascorbic acid and Fe 3 O 4 catalyst.

  16. Improving the extraction of l-phenylalanine by the use of ionic liquids as adjuvants in aqueous biphasic systems.

    PubMed

    Yang, Hongpeng; Chen, Li; Zhou, Cunshan; Yu, Xiaojie; Yagoub, Abu ElGasim A; Ma, Haile

    2018-04-15

    Polyethylene glycol (PEG) is widely used in the polymer-salt systems. However, the low polarity of the PEG-rich phase limits the application of aqueous biphasic systems (ABS). To overcome this disadvantage, a small quantity of ionic liquid (IL) was used as an adjuvant in ABS to enlarge the polarity range. Therefore, an innovative study involving addition of 4wt% imidazolium-based ILs to the PEG 600/NaH 2 PO 4 ABS, aiming at controlling the phase behavior and extraction ability, was carried out. The phase diagrams, the tie-lines and the partitioning behavior of l-phenylalanine and ILs were studied in these systems. The results reveal that l-phenylalanine preferentially partitions for the PEG-rich phase. The addition of 4wt% IL to ABS controls the partitioning behavior of l-phenylalanine, which depends on the type of IL employed. Moreover, it is verified that increasing temperature lead to a decrease in the partition coefficient of l-phenylalanine. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Stable Isotope-Assisted Metabolic Profiling Reveals Growth Mode Dependent Differential Metabolism and Multiple Catabolic Pathways of l-Phenylalanine in Rubrivivax benzoatilyticus JA2.

    PubMed

    Mekala, Lakshmi Prasuna; Mohammed, Mujahid; Chintalapati, Sasikala; Chintalapati, Venkata Ramana

    2018-01-05

    Anoxygenic phototrophic bacteria are metabolically versatile and survive under different growth modes using diverse organic compounds, yet their metabolic diversity is largely unexplored. In the present study, we employed stable-isotope-assisted metabolic profiling to unravel the l-phenylalanine catabolism in Rubrivivax benzoatilyticus JA2 under varying growth modes. Strain JA2 grows under anaerobic and aerobic conditions by utilizing l-phenylalanine as a nitrogen source. Furthermore, ring-labeled 13 C 6 -phenylalanine feeding followed by liquid chromatography-mass spectrometry exometabolite profiling revealed 60 labeled metabolic features (M + 6, M + 12, and M + 18) derived solely from l-phenylalanine, of which 11 were identified, 7 putatively identified, and 42 unidentified under anaerobic and aerobic conditions. However, labeled metabolites were significantly higher in aerobic compared to anaerobic conditions. Furthermore, detected metabolites and enzyme activities indicated multiple l-phenylalanine catabolic routes mainly Ehrlich, homogentisate-dependent melanin, benzenoid, and unidentified pathways operating under anaerobic and aerobic conditions in strain JA2. Interestingly, the study indicated l-phenylalanine-dependent and independent benzenoid biosynthesis in strain JA2 and a differential flux of l-phenylalanine to Ehrlich and benzenoid pathways under anaerobic and aerobic conditions. Additionally, unidentified labeled metabolites strongly suggest the presence of unknown phenylalanine catabolic routes in strain JA2. Overall, the study uncovered the l-phenylalanine catabolic diversity in strain JA2 and demonstrated the potential of stable isotope-assisted metabolomics in unraveling the hidden metabolic repertoire.

  18. Preparation of N-(2-alkoxyvinyl)sulfonamides from N-tosyl-1,2,3-triazoles and Subsequent Conversion to Substituted Phthalans and Phenethylamines.

    PubMed

    Bennett, John M; Shapiro, Jonathan D; Choinski, Krystina N; Mei, Yingbin; Aulita, Sky M; Dominguez, Giovanny M; Majireck, Max M

    2018-01-03

    Decomposition of N-tosyl-1,2,3-triazoles with rhodium(II) acetate dimer in the presence of alcohols forms synthetically versatile N-(2-alkoxyvinyl)sulfonamides, which react under a variety of conditions to afford useful N- and O-containing compounds. Acid-catalyzed addition of alcohols or thiols to N-(2-alkoxyvinyl)sulfonamide-containing phthalans provides access to ketals and thioketals, respectively. Selective reduction of the vinyl group in N-(2-alkoxyvinyl)sulfonamide-containing phthalans via hydrogenation yields the corresponding phthalan in good yield, whereas reduction with sodium bis(2-methoxyethoxy)aluminumhydride generates a ring-opened phenethylamine analogue. Because the N-(2-alkoxyvinyl)sulfonamide functional group is synthetically versatile, but often hydrolytically unstable, this protocol emphasizes key techniques in preparing, handling, and reacting these pivotal substrates in several useful transformations.

  19. Identification of a plastidial phenylalanine exporter that influences flux distribution through the phenylalanine biosynthetic network

    PubMed Central

    Widhalm, Joshua R.; Gutensohn, Michael; Yoo, Heejin; Adebesin, Funmilayo; Qian, Yichun; Guo, Longyun; Jaini, Rohit; Lynch, Joseph H.; McCoy, Rachel M.; Shreve, Jacob T.; Thimmapuram, Jyothi; Rhodes, David; Morgan, John A.; Dudareva, Natalia

    2015-01-01

    In addition to proteins, L-phenylalanine is a versatile precursor for thousands of plant metabolites. Production of phenylalanine-derived compounds is a complex multi-compartmental process using phenylalanine synthesized predominantly in plastids as precursor. The transporter(s) exporting phenylalanine from plastids, however, remains unknown. Here, a gene encoding a Petunia hybrida plastidial cationic amino-acid transporter (PhpCAT) functioning in plastidial phenylalanine export is identified based on homology to an Escherichia coli phenylalanine transporter and co-expression with phenylalanine metabolic genes. Radiolabel transport assays show that PhpCAT exports all three aromatic amino acids. PhpCAT downregulation and overexpression result in decreased and increased levels, respectively, of phenylalanine-derived volatiles, as well as phenylalanine, tyrosine and their biosynthetic intermediates. Metabolic flux analysis reveals that flux through the plastidial phenylalanine biosynthetic pathway is reduced in PhpCAT RNAi lines, suggesting that the rate of phenylalanine export from plastids contributes to regulating flux through the aromatic amino-acid network. PMID:26356302

  20. Identification of a plastidial phenylalanine exporter that influences flux distribution through the phenylalanine biosynthetic network

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Widhalm, Joshua R.; Gutensohn, Michael; Yoo, Heejin

    In addition to proteins, L-phenylalanine is a versatile precursor for thousands of plant metabolites. Production of phenylalanine-derived compounds is a complex multi-compartmental process using phenylalanine synthesized predominantly in plastids as precursor. The transporter(s) exporting phenylalanine from plastids, however, remains unknown. Here, a gene encoding a Petunia hybrida plastidial cationic amino-acid transporter (PhpCAT) functioning in plastidial phenylalanine export is identified based on homology to an Escherichia coli phenylalanine transporter and co-expression with phenylalanine metabolic genes. Radiolabel transport assays show that PhpCAT exports all three aromatic amino acids. PhpCAT downregulation and overexpression result in decreased and increased levels, respectively, of phenylalanine-derived volatiles,more » as well as phenylalanine, tyrosine and their biosynthetic intermediates. Metabolic flux analysis reveals that flux through the plastidial phenylalanine biosynthetic pathway is reduced in PhpCAT RNAi lines, suggesting that the rate of phenylalanine export from plastids contributes to regulating flux through the aromatic amino-acid network.« less

  1. Identification of a plastidial phenylalanine exporter that influences flux distribution through the phenylalanine biosynthetic network

    DOE PAGES

    Widhalm, Joshua R.; Gutensohn, Michael; Yoo, Heejin; ...

    2015-09-10

    In addition to proteins, L-phenylalanine is a versatile precursor for thousands of plant metabolites. Production of phenylalanine-derived compounds is a complex multi-compartmental process using phenylalanine synthesized predominantly in plastids as precursor. The transporter(s) exporting phenylalanine from plastids, however, remains unknown. Here, a gene encoding a Petunia hybrida plastidial cationic amino-acid transporter (PhpCAT) functioning in plastidial phenylalanine export is identified based on homology to an Escherichia coli phenylalanine transporter and co-expression with phenylalanine metabolic genes. Radiolabel transport assays show that PhpCAT exports all three aromatic amino acids. PhpCAT downregulation and overexpression result in decreased and increased levels, respectively, of phenylalanine-derived volatiles,more » as well as phenylalanine, tyrosine and their biosynthetic intermediates. Metabolic flux analysis reveals that flux through the plastidial phenylalanine biosynthetic pathway is reduced in PhpCAT RNAi lines, suggesting that the rate of phenylalanine export from plastids contributes to regulating flux through the aromatic amino-acid network.« less

  2. Sorafenib tosylate, Ribavirn and Sofosbuvir combination therapy for HCV virus infected patients with decompensated liver cancer.

    PubMed

    Munir, Bushra; Ahmed, Bilal; Kiran, Shumaila; Jalal, Fatima; Zahoor, Muhammad Kashif; Shehzadi, Saba; Oranab, Sadaf; Kamran, Sayed Kashif; Ghaffar, Abdul

    2017-11-01

    Hepatitis C is the most common health problem worldwide and is major cause of death due to proliferation of hepatocellular carcinoma. The medicines available for HCV treatment overcome up-to 95% complications of HCV. However, liver cancer needs some additional care. Normally Sorafenib tosylate 200 mg is recommended for liver cancer. There is no such trial in which this drug could effectively be used in combination of direct acting antivirals for HCV. The study was conducted for HCV patients (n=30) with liver cancer having decompensated stage. Combination of Sorafenib tosylate, Ribavirn and Sofosbuvir were used for the pharmacokinetics of these medicines. Child pugh score less then 7 (CP A) in adults during treatment phase (received 12 weeks of Sorafenib tosylate 200 mg, Ribavirn and Sofosbuvir 400 mg once daily) have no side effect while child pugh score 7-9 (CP B) have evidence of hypertension. The main efficiency end point sustained virology response with overcoming liver cancer as well in 12 weeks after end treatment (SVR-LLC 12). Mean pharmacokinetic exposure to Sorafenib tosylate 200 mg, Ribavirn and Sofosbuvir at week 8th was 2.1, 1.5,1.2 times greater in CP B than in CP A. Adverse effects (AEs) were observed in 12 out of 30 patients but not severe as lethal for life. Treatment with Sorafenib tosylate, Ribavirn and Sofosbuvir for twelve weeks was harmless and well accepted, 100 % patients achieve (SVR LLC 12) with 10-fold cure rate more than previous ones. The combination therapy of Sorafenib tosylate, Ribavirn and Sofosbuvir was found helpful for the management of decompensated liver cancer.

  3. The self-assembling zwitterionic form of L-phenylalanine at neutral pH.

    PubMed

    Mossou, Estelle; Teixeira, Susana C M; Mitchell, Edward P; Mason, Sax A; Adler-Abramovich, Lihi; Gazit, Ehud; Forsyth, V Trevor

    2014-03-01

    The title zwitterion (2S)-2-azaniumyl-1-hydroxy-3-phenylpropan-1-olate, C9H11NO2, also known as L-phenylalanine, was characterized using synchrotron X-rays. It crystallized in the monoclinic space group P21 with four molecules in the asymmetric unit. The 0.62 Å resolution structure is assumed to be closely related to the fibrillar form of phenylalanine, as observed by electron microscopy and electron diffraction. The structure exists in a zwitterionic form in which π-π stacking and hydrogen-bonding interactions are believed to form the basis of the self-assembling properties.

  4. Thermodynamics of the complex formation of copper(II) with L-phenylalanine in aqueous ethanol solutions

    NASA Astrophysics Data System (ADS)

    Burov, D. M.; Ledenkov, S. F.; Vandyshev, V. N.

    2013-05-01

    Constants of the acid dissociation and complexation of L-phenylalanine (HPhe) with copper(II) ions are determined by potentiometry in aqueous ethanol solutions containing 0 to 0.7 molar fraction of alcohol. Changes in the Gibbs energy for the transfer from water to a binary solvent of L-phenylalanine, Phe- anion, and [CuPhe]+ complex are calculated. It is found that the weakening of solvation of the ligand donor groups in solvents with high ethanol contents is accompanied by an increase in the stability of [CuPhe]+ complex.

  5. Preparation of "dummy" l-phenylalanine molecularly imprinted microspheres by using ionic liquid as a template and functional monomer.

    PubMed

    Li, Ji; Hu, Xiaoling; Guan, Ping; Song, Dongmen; Qian, Liwei; Du, Chunbao; Song, Renyuan; Wang, Chaoli

    2015-07-07

    In this study, dummy imprinting technology was employed for the preparation of l-phenylalanine-imprinted microspheres. Ionic liquids were utilized as both a "dummy" template and functional monomer, and 4-vinylpyridine and ethylene glycol dimethacrylate were used as the assistant monomer and cross-linker, respectively, for preparing a surface-imprinted polymer on poly(divinylbenzene) microspheres. By the results obtained by theoretical investigation, the interaction between the template and monomer complex was improved as compared with that between the template and the traditional l-phenylalanine-imprinted polymer. The batch experiments indicated that the imprinting factor reached 2.5. Scatchard analysis demonstrated that the obtained "dummy" molecularly imprinted microspheres exhibited an affinity of 77.4 M·10 -4 , significantly higher that of a traditional polymer directly prepared by l-phenylalanine, which is in agreement with theoretical results. Competitive adsorption experiments also showed that the molecularly imprinted polymer with the dummy template effectively isolated l-phenylalanine from l-histidine and l-tryptophan with separation factors of 5.68 and 2.68, respectively. All these results demonstrated that the polymerizable ionic liquid as the dummy template could enhance the affinity and selectivity of molecularly imprinted polymer, thereby promoting the development of imprinting technology for biomolecules. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. 21 CFR 201.21 - Declaration of presence of phenylalanine as a component of aspartame in over-the-counter and...

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... acids are so combined to form aspartame (1-methyl N-L-α-aspartyl-L-phenylalanine), they produce an... 21 Food and Drugs 4 2013-04-01 2013-04-01 false Declaration of presence of phenylalanine as a...: GENERAL LABELING General Labeling Provisions § 201.21 Declaration of presence of phenylalanine as a...

  7. 21 CFR 201.21 - Declaration of presence of phenylalanine as a component of aspartame in over-the-counter and...

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... acids are so combined to form aspartame (1-methyl N-L-α-aspartyl-L-phenylalanine), they produce an... 21 Food and Drugs 4 2012-04-01 2012-04-01 false Declaration of presence of phenylalanine as a...: GENERAL LABELING General Labeling Provisions § 201.21 Declaration of presence of phenylalanine as a...

  8. 21 CFR 201.21 - Declaration of presence of phenylalanine as a component of aspartame in over-the-counter and...

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... acids are so combined to form aspartame (1-methyl N-L-α-aspartyl-L-phenylalanine), they produce an... 21 Food and Drugs 4 2011-04-01 2011-04-01 false Declaration of presence of phenylalanine as a...: GENERAL LABELING General Labeling Provisions § 201.21 Declaration of presence of phenylalanine as a...

  9. 21 CFR 201.21 - Declaration of presence of phenylalanine as a component of aspartame in over-the-counter and...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... acids are so combined to form aspartame (1-methyl N-L-α-aspartyl-L-phenylalanine), they produce an... 21 Food and Drugs 4 2010-04-01 2010-04-01 false Declaration of presence of phenylalanine as a...: GENERAL LABELING General Labeling Provisions § 201.21 Declaration of presence of phenylalanine as a...

  10. 21 CFR 201.21 - Declaration of presence of phenylalanine as a component of aspartame in over-the-counter and...

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... acids are so combined to form aspartame (1-methyl N-L-α-aspartyl-L-phenylalanine), they produce an... 21 Food and Drugs 4 2014-04-01 2014-04-01 false Declaration of presence of phenylalanine as a...: GENERAL LABELING General Labeling Provisions § 201.21 Declaration of presence of phenylalanine as a...

  11. 29 CFR 1926.1106 - Methyl chloromethyl ether.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Toxic and Hazardous Substances § 1926.1106 Methyl chloromethyl ether. Note: The requirements applicable to construction work under this...

  12. Polarized optical absorption and photoluminescence measurements in single-crystal thin films of 4'-dimethylamino-N-methyl-4-stilbazolium tosylate

    NASA Astrophysics Data System (ADS)

    Bhowmik, Achintya K.; Xu, Jianjun; Thakur, Mrinal

    1999-11-01

    Single-crystal thin films of the anhydrous (red) and the hydrated (orange) phases of the organic salt 4'-dimethylamino-N-methyl-4-stilbazolium tosylate were grown by a modification of the shear method. The optical absorption coefficients of the films were measured with light polarized along and normal to the dipole/molecular axis at both resonant and off-resonant wavelengths, and a strong dichroism was observed at the resonant wavelengths. The absorption measurements are important considering potential applications of these films (red phase) in high-speed single-pass thin-film electro-optic modulators [M. Thakur, J. Xu, A. Bhowmik, and L. Zhou, Appl. Phys. Lett. 74, 635 (1999)] and other photonic devices. Highly polarized photoluminescence (PL) has been observed in these films. The PL efficiencies of the red- and orange-phase single-crystal films were measured to be about 12% and 14%, respectively, which are significantly higher than the maximum PL efficiency measured in solution (3%).

  13. 29 CFR 1910.1006 - Methyl chloromethyl ether.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 6 2011-07-01 2011-07-01 false Methyl chloromethyl ether. 1910.1006 Section 1910.1006 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS (CONTINUED) Toxic and Hazardous...

  14. 29 CFR 1926.1108 - bis-Chloromethyl ether.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Toxic and Hazardous Substances § 1926.1108 bis-Chloromethyl ether. Note: The requirements applicable to construction work under this section are identical to...

  15. Taming tosyl azide: the development of a scalable continuous diazo transfer process.

    PubMed

    Deadman, Benjamin J; O'Mahony, Rosella M; Lynch, Denis; Crowley, Daniel C; Collins, Stuart G; Maguire, Anita R

    2016-04-07

    Heat and shock sensitive tosyl azide was generated and used on demand in a telescoped diazo transfer process. Small quantities of tosyl azide were accessed in a 'one pot' batch procedure using shelf stable, readily available reagents. For large scale diazo transfer reactions tosyl azide was generated and used in a telescoped flow process, to mitigate the risks associated with handling potentially explosive reagents on scale. The in situ formed tosyl azide was used to rapidly perform diazo transfer to a range of acceptors, including β-ketoesters, β-ketoamides, malonate esters and β-ketosulfones. An effective in-line quench of sulfonyl azides was also developed, whereby a sacrificial acceptor molecule ensured complete consumption of any residual hazardous diazo transfer reagent. The telescoped diazo transfer process with in-line quenching was used to safely prepare over 21 g of an α-diazocarbonyl in >98% purity without any column chromatography.

  16. 40 CFR 721.5585 - 4,4′-(1-methylethylidene)bisphenol, polymer with (chloromethyl)oxirane and a diamine (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., polymer with (chloromethyl)oxirane and a diamine (generic). 721.5585 Section 721.5585 Protection of...-methylethylidene)bisphenol, polymer with (chloromethyl)oxirane and a diamine (generic). (a) Chemical substance and...-methylethylidene)bisphenol, polymer with (chloromethyl) oxirane and a diamine (PMN P-97-0916) is subject to...

  17. 40 CFR 721.5585 - 4,4′-(1-methylethylidene)bisphenol, polymer with (chloromethyl)oxirane and a diamine (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., polymer with (chloromethyl)oxirane and a diamine (generic). 721.5585 Section 721.5585 Protection of...-methylethylidene)bisphenol, polymer with (chloromethyl)oxirane and a diamine (generic). (a) Chemical substance and...-methylethylidene)bisphenol, polymer with (chloromethyl) oxirane and a diamine (PMN P-97-0916) is subject to...

  18. 40 CFR 721.5585 - 4,4′-(1-methylethylidene)bisphenol, polymer with (chloromethyl)oxirane and a diamine (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., polymer with (chloromethyl)oxirane and a diamine (generic). 721.5585 Section 721.5585 Protection of...-methylethylidene)bisphenol, polymer with (chloromethyl)oxirane and a diamine (generic). (a) Chemical substance and...-methylethylidene)bisphenol, polymer with (chloromethyl) oxirane and a diamine (PMN P-97-0916) is subject to...

  19. 40 CFR 721.5585 - 4,4′-(1-methylethylidene)bisphenol, polymer with (chloromethyl)oxirane and a diamine (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., polymer with (chloromethyl)oxirane and a diamine (generic). 721.5585 Section 721.5585 Protection of...-methylethylidene)bisphenol, polymer with (chloromethyl)oxirane and a diamine (generic). (a) Chemical substance and...-methylethylidene)bisphenol, polymer with (chloromethyl) oxirane and a diamine (PMN P-97-0916) is subject to...

  20. Effects of a common worldwide drink (Beer) on L-Phenylalanine and L-Tyrosine fibrillar assemblies

    NASA Astrophysics Data System (ADS)

    Banik, Debasis; Banerjee, Pavel; Sabeehuddin, Ghazi; Sarkar, Nilmoni

    2017-11-01

    In this letter, small amount of beer [0.42-2.08% (v/v)] is employed to investigate the fibril inhibition kinetics of 1 mM L-Phenylalanine and L-Tyrosine (relevant to disease condition) using Fluorescence Lifetime imaging Microscopy (FLIM), Field Emission Scanning Electron Microscopy (FESEM) and High Resolution Transmission Electron Microscopic (HR-TEM) techniques. Our results indicate that 1.67 and 0.42% of beer is sufficient for effective breakdown of L-Phe and L-Tyr assemblies, respectively. Quantitative information about fibril inhibition is obtained from Fluorescence Correlation Spectroscopic (FCS) measurements. We have shown that the morphology of L-Phe changes to L-Tyr in presence of 2,2‧-Bipyridine-3,3‧-diol (BP(OH)2).

  1. The use of a food supplementation with D-phenylalanine, L-glutamine and L-5-hydroxytriptophan in the alleviation of alcohol withdrawal symptoms.

    PubMed

    Jukić, Tomislav; Rojc, Bojan; Boben-Bardutzky, Darja; Hafner, Mateja; Ihan, Alojz

    2011-12-01

    We described the use of a food supplementation with D-phenylalanine, L-glutamine and L-5-hydroxytriptophan in the alleviation of alcohol withdrawal symptoms in patients starting a detoxification therapy. Since abstinence from ethanol causes a hypodopaminergic and a hypoopioidergic environment in the reword system circuits, manifesting with withdrawal symptoms, food supplements that contains D-phenylalanine a peptidase inhibitor (of opioide inactivation) and L-amino-acids (for dopamine synthesis) were used to replenish a lack in neurotransmitters and alleviate the symptoms of alcohol withdrawal. 20 patients suffering from alcohol addictions starting a detoxification therapy have been included in a prospective, randomized, double blind study. The patients have been randomly devided in two groups. One group recieved for a period of 40 days a food supplement containing D-phenylalanine, L-glutamine and L-5-hydroxytriptophan (investigation group), and the control (placebo) group. On the first day of hospitalization the patients performed a SCL-90-R test, and blood samples were taken for measuring liver enzymes, total bilirubin, unbound cortisol and lymphocyte populations. The same was done on the 40th day of hospitalization. During the therapy a significant decrease in SCL-90-R psychiatric symptoms scores and a significant increase in CD4 lymphocyte count was observed in the investigation group. The cortisol values were significantly, but equally decreased in both groups, the same was with the liver enzymes and the total bilirubin values. We conclude that abstinence causes a major stress for the patients. The use of food supplement containing D-phenylalanine, L-glutamine and L-5-hydroxytriptophan alleviates the withdrawal symptoms and causes a rise in CD4 lymphocyte population, but it dose not affect the serum cortisol levels, which are probably more affected by liver inflammation and the liver restitution.

  2. 29 CFR 1910.1006 - Methyl chloromethyl ether.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 6 2014-07-01 2013-07-01 true Methyl chloromethyl ether. 1910.1006 Section 1910.1006 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS (CONTINUED) Toxic and Hazardous Substances § 1910.1006...

  3. 29 CFR 1910.1008 - bis-Chloromethyl ether.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 6 2011-07-01 2011-07-01 false bis-Chloromethyl ether. 1910.1008 Section 1910.1008 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS (CONTINUED) Toxic and Hazardous Substances § 1910.1008...

  4. 29 CFR 1910.1008 - bis-Chloromethyl ether.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 6 2014-07-01 2013-07-01 true bis-Chloromethyl ether. 1910.1008 Section 1910.1008 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS (CONTINUED) Toxic and Hazardous Substances § 1910.1008...

  5. Amino acid N-malonyltransferases from mung beans. Action on 1-aminocyclopropane-1-carboxylic acid and D-phenylalanine.

    PubMed

    Guo, L; Phillips, A T; Arteca, R N

    1993-12-05

    1-Aminocyclopropane-1-carboxylate (ACC) N-malonyltransferase from etiolated mung bean hypocotyls was examined for its relationship to D-phenylalanine N-malonyltransferase and other enzymes which transfer malonyl groups from malonyl-CoA to D-amino acids. Throughout a 3600-fold purification the ratio of D-phenylalanine N-malonyltransferase activity to ACC N-malonyltransferase activity was unchanged. Antibodies raised against purified ACC N-malonyltransferase 55-kDa protein were also able to precipitate all D-phenylalanine-directed activity from partially purified mung bean extracts. The irreversible inhibitors phenylglyoxal and tetranitromethane reduced malonyltransferase activity towards D-phenylalanine to the same extent as that for ACC. In addition, several other D-amino acids, particularly D-tryptophan and D-tyrosine, were able to inhibit action towards both ACC and D-phenylalanine. These lines of evidence suggest that a single enzyme is capable of promoting malonylation of both ACC and D-phenylalanine. Km values for D-phenylalanine and malonyl-CoA were found to be 48 and 43 microM, respectively; these values are 10-fold lower than the corresponding values when ACC was substrate. Coenzyme A was a noncompetitive (mixed type) product inhibitor towards malonyl-CoA at both unsaturated and saturated ACC concentrations. The enzyme was also inhibited uncompetitively at high concentrations of malonyl-CoA. We propose that the enzyme follows an Ordered Bi-Bi reaction pathway, with the amino acid substrate being bound initially.

  6. Activation of phenylalanine hydroxylase by phenylalanine does not require binding in the active site.

    PubMed

    Roberts, Kenneth M; Khan, Crystal A; Hinck, Cynthia S; Fitzpatrick, Paul F

    2014-12-16

    Phenylalanine hydroxylase (PheH), a liver enzyme that catalyzes the hydroxylation of excess phenylalanine in the diet to tyrosine, is activated by phenylalanine. The lack of activity at low levels of phenylalanine has been attributed to the N-terminus of the protein's regulatory domain acting as an inhibitory peptide by blocking substrate access to the active site. The location of the site at which phenylalanine binds to activate the enzyme is unknown, and both the active site in the catalytic domain and a separate site in the N-terminal regulatory domain have been proposed. Binding of catecholamines to the active-site iron was used to probe the accessibility of the active site. Removal of the regulatory domain increases the rate constants for association of several catecholamines with the wild-type enzyme by ∼2-fold. Binding of phenylalanine in the active site is effectively abolished by mutating the active-site residue Arg270 to lysine. The k(cat)/K(phe) value is down 10⁴ for the mutant enzyme, and the K(m) value for phenylalanine for the mutant enzyme is >0.5 M. Incubation of the R270K enzyme with phenylalanine also results in a 2-fold increase in the rate constants for catecholamine binding. The change in the tryptophan fluorescence emission spectrum seen in the wild-type enzyme upon activation by phenylalanine is also seen with the R270K mutant enzyme in the presence of phenylalanine. Both results establish that activation of PheH by phenylalanine does not require binding of the amino acid in the active site. This is consistent with a separate allosteric site, likely in the regulatory domain.

  7. Activation of Phenylalanine Hydroxylase by Phenylalanine Does Not Require Binding in the Active Site

    PubMed Central

    2015-01-01

    Phenylalanine hydroxylase (PheH), a liver enzyme that catalyzes the hydroxylation of excess phenylalanine in the diet to tyrosine, is activated by phenylalanine. The lack of activity at low levels of phenylalanine has been attributed to the N-terminus of the protein’s regulatory domain acting as an inhibitory peptide by blocking substrate access to the active site. The location of the site at which phenylalanine binds to activate the enzyme is unknown, and both the active site in the catalytic domain and a separate site in the N-terminal regulatory domain have been proposed. Binding of catecholamines to the active-site iron was used to probe the accessibility of the active site. Removal of the regulatory domain increases the rate constants for association of several catecholamines with the wild-type enzyme by ∼2-fold. Binding of phenylalanine in the active site is effectively abolished by mutating the active-site residue Arg270 to lysine. The kcat/Kphe value is down 104 for the mutant enzyme, and the Km value for phenylalanine for the mutant enzyme is >0.5 M. Incubation of the R270K enzyme with phenylalanine also results in a 2-fold increase in the rate constants for catecholamine binding. The change in the tryptophan fluorescence emission spectrum seen in the wild-type enzyme upon activation by phenylalanine is also seen with the R270K mutant enzyme in the presence of phenylalanine. Both results establish that activation of PheH by phenylalanine does not require binding of the amino acid in the active site. This is consistent with a separate allosteric site, likely in the regulatory domain. PMID:25453233

  8. Interaction of N-benzoyl-D-phenylalanine and related compounds with the sulphonylurea receptor of beta-cells.

    PubMed

    Schwanstecher, C; Meyer, M; Schwanstecher, M; Panten, U

    1998-03-01

    1. The structure activity relationships for the insulin secretagogues N-benzoyl-D-phenylalanine (NBDP) and related compounds were examined at the sulphonylurea receptor level by use of cultured HIT-T15 and mouse pancreatic beta-cells. The affinities of these compounds for the sulphonylurea receptor were compared with their potencies for K(ATP)-channel inhibition. In addition, the effects of cytosolic nucleotides on K(ATP)-channel inhibition by NBDP were investigated. 2. NBDP displayed a dissociation constant for binding to the sulphonylurea receptor (K(D) value) of 11 microM and half-maximally effective concentrations of K(ATP)-channel inhibition (EC50 values) between 2 and 4 microM (in the absence of cytosolic nucleotides or presence of 0.1 mM GDP or 1 mM ADP). 3. In the absence of cytosolic nucleotides or presence of GDP (0.1 mM) maximally effective concentrations of NBDP (0.1-1 mM) reduced K(ATP)-channel activity to 47% and 44% of control, respectively. In the presence of ADP (1 mM), K(ATP)-channel activity was completely suppressed by 0.1 mM NBDP. 4. The L-isomer of N-benzoyl-phenylalanine displayed a 20 fold lower affinity and an 80 fold lower potency than the D-isomer. 5. Introduction of a p-nitro substituent in the D-phenylalanine moiety of NBDP did not decrease lipophilicity but lowered affinity and potency by more than 30 fold. 6. Introduction of a p-amino substituent in the D-phenylalanine moiety of NBDP (N-benzoyl-p-amino-D-phenylalanine, NBADP) reduced lipophilicity and lowered affinity and potency by about 10 fold. This loss of affinity and potency was compensated for by formation of the phenylpropionic acid derivative of NBADP. A similar difference in affinity was observed for the sulphonylurea carbutamide and its phenylpropionic acid derivative. 7. Replacing the benzene ring in the D-phenylalanine moiety of NBDP by a cyclohexyl ring increased lipophilicity, and the K(D) and EC50 values were slightly lower than for NBDP. Exchange of both benzene rings

  9. Interaction of N-benzoyl-D-phenylalanine and related compounds with the sulphonylurea receptor of β-cells

    PubMed Central

    Schwanstecher, Christina; Meyer, Miriam; Schwanstecher, Mathias; Panten, Uwe

    1998-01-01

    The structure activity relationships for the insulin secretagogues N-benzoyl-D-phenylalanine (NBDP) and related compounds were examined at the sulphonylurea receptor level by use of cultured HIT-T15 and mouse pancreatic β-cells. The affinities of these compounds for the sulphonylurea receptor were compared with their potencies for KATP-channel inhibition. In addition, the effects of cytosolic nucleotides on KATP-channel inhibition by NBDP were investigated.NBDP displayed a dissociation constant for binding to the sulphonylurea receptor (KD value) of 11 μM and half-maximally effective concentrations of KATP-channel inhibition (EC50 values) between 2 and 4 μM (in the absence of cytosolic nucleotides or presence of 0.1 mM GDP or 1 mM ADP).In the absence of cytosolic nucleotides or presence of GDP (0.1 mM) maximally effective concentrations of NBDP (0.1–1 mM) reduced KATP-channel activity to 47% and 44% of control, respectively. In the presence of ADP (1 mM), KATP-channel activity was completely suppressed by 0.1 mM NBDP.The L-isomer of N-benzoyl-phenylalanine displayed a 20 fold lower affinity and an 80 fold lower potency than the D-isomer.Introduction of a p-nitro substituent in the D-phenylalanine moiety of NBDP did not decrease lipophilicity but lowered affinity and potency by more than 30 fold.Introduction of a p-amino substituent in the D-phenylalanine moiety of NBDP (N-benzoyl-p-amino-D-phenylalanine, NBADP) reduced lipophilicity and lowered affinity and potency by about 10 fold. This loss of affinity and potency was compensated for by formation of the phenylpropionic acid derivative of NBADP. A similar difference in affinity was observed for the sulphonylurea carbutamide and its phenylpropionic acid derivative.Replacing the benzene ring in the D-phenylalanine moiety of NBDP by a cyclohexyl ring increased lipophilicity, and the KD and EC50 values were slightly lower than for NBDP. Exchange of both benzene rings in NBDP by cyclohexyl rings

  10. Electrochemical determination of L-phenylalanine at polyaniline modified carbon electrode based on β-cyclodextrin incorporated carbon nanotube composite material and imprinted sol-gel film.

    PubMed

    Hu, Yu-fang; Zhang, Zhao-hui; Zhang, Hua-bin; Luo, Li-juan; Yao, Shou-zhuo

    2011-04-15

    A sensitive and selective electrochemical sensor based on a polyaniline modified carbon electrode for the determination of L-phenylalanine has been proposed by utilizing β-cyclodextrin (β-CD) incorporated multi-walled carbon nanotube (MWNT) and imprinted sol-gel film. The electrochemical behavior of the sensor towards L-phenylalanine was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and amperometric i-t curve. The surface morphologies of layer-by-layer assembly electrodes were displayed by scanning electron microscope (SEM). The response mechanism of the imprinted sensor for L-phenylalanine was based on the inclusion interaction of β-CD and molecular recognition capacity of the imprinted film for L-phenylalanine. A linear calibration plot was obtained covering the concentration range from 5.0 × 10(-7) to 1.0 × 10(-4) mol L(-1) with a detection limit of 1.0 × 10(-9) mol L(-1). With excellent sensitivity, selectivity, stability, reproducibility and recovery, the electrochemical imprinted sensor was used to detect L-phenylalanine in blood plasma samples successfully. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Differential metabolism of L-phenylalanine in the formation of aromatic volatiles in melon (Cucumis melo L.) fruit.

    PubMed

    Gonda, Itay; Davidovich-Rikanati, Rachel; Bar, Einat; Lev, Shery; Jhirad, Pliaa; Meshulam, Yuval; Wissotsky, Guy; Portnoy, Vitaly; Burger, Joseph; Schaffer, Arthur A; Tadmor, Yaakov; Giovannoni, James J; Fei, Zhangjun; Fait, Aaron; Katzir, Nurit; Lewinsohn, Efraim

    2018-04-01

    Studies on the active pathways and the genes involved in the biosynthesis of L-phenylalanine-derived volatiles in fleshy fruits are sparse. Melon fruit rinds converted stable-isotope labeled L-phe into more than 20 volatiles. Phenylpropanes, phenylpropenes and benzenoids are apparently produced via the well-known phenylpropanoid pathway involving phenylalanine ammonia lyase (PAL) and being (E)-cinnamic acid a key intermediate. Phenethyl derivatives seemed to be derived from L-phe via a separate biosynthetic route not involving (E)-cinnamic acid and PAL. To explore for a biosynthetic route to (E)-cinnamaldehyde in melon rinds, soluble protein cell-free extracts were assayed with (E)-cinnamic acid, CoA, ATP, NADPH and MgSO 4 , producing (E)-cinnamaldehyde in vitro. In this context, we characterized CmCNL, a gene encoding for (E)-cinnamic acid:coenzyme A ligase, inferred to be involved in the biosynthesis of (E)-cinnamaldehyde. Additionally we describe CmBAMT, a SABATH gene family member encoding a benzoic acid:S-adenosyl-L-methionine carboxyl methyltransferase having a role in the accumulation of methyl benzoate. Our approach leads to a more comprehensive understanding of L-phe metabolism into aromatic volatiles in melon fruit. Copyright © 2018 Elsevier Ltd. All rights reserved.

  12. Phosphoenolpyruvate Transporter Enables Targeted Perturbation During Metabolic Analysis of L-Phenylalanine Production With Escherichia coli.

    PubMed

    Tröndle, Julia; Albermann, Christoph; Weiner, Michael; Sprenger, Georg A; Weuster-Botz, Dirk

    2018-05-01

    Usually perturbation of the metabolism of cells by addition of substrates is applied for metabolic analysis of production organisms, but perturbation studies are restricted to the endogenous substrates of the cells under study. The goal of this study is to overcome this limitation by making phosphoenolpyruvate (PEP) available for perturbation studies with Escherichia coli producing L-phenylalanine. A production strain overexpressing a PEP-transporter variant (UhpT-D388C) is applied in a standardized fed-batch production-process on a 42 L-scale. Four parallel short-term perturbation experiments of 20 min are performed with glucose and glycerol as fed-batch carbon sources after rapid media transition of cells from the production-process. PEP is added after 9 min and is immediately consumed by the cells with up to 1.5 mmol g CDW -1  h -1 . L-phenylalanine production rates increased by up to 200% after addition of PEP. This clearly indicates an intracellular PEP-limitation in the L-phenylalanine production strain under study. Thus, it is shown that overexpressing specific transporters for analytical reasons makes exogenous substrates available as perturbation substrates for metabolic analyses of cells sampled from production-processes and thereby allows a very targeted perturbation of whole-cell metabolism. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Thermodynamic Parameters of the Dissolution of 4-Hydroxy-L-Proline and L-Phenylalanine in Mixed Aqueous Solvents at 298 K

    NASA Astrophysics Data System (ADS)

    Smirnov, V. I.; Badelin, V. G.

    2018-01-01

    The enthalpies of solution of 4-hydroxy-L-proline and L-phenylalanine in binary mixed aqueous solvents containing acetonitrile (AN), 1,4-dioxane (1,4-DO), or acetone (AC) at mole fractions of 0 to 0.25 are determined at T = 298.15 K via isothermal calorimetry. The standard enthalpies of solution (Δsol H°) and transfer (Δtr H°) of 4-hydroxy-L-proline and L-phenylalanine from water to mixed aqueous solvents are calculated using the experimental calorimetric data, as are the enthalpy coefficients of paired interactions ( h xy ) between the molecules of the investigated amino acids and the organic solvents. The effects the mixed aqueous solvent composition and the structure of the organic solvent molecules have on the enthalpies of solution and transfer for the investigated amino acids are considered. The correlation between the enthalpy of solution of the amino acids and the electron-donating properties of the organic solvents in the mixed aqueous solvent systems is established.

  14. SO 2 Phototriggered Crystalline Nanomechanical Transduction of Aromatic Rotors in Tosylates: Rationalization via Photocrystallography of [Ru(NH 3 ) 4 SO 2 X]tosylate 2 (X = pyridine, 3-Cl-pyridine, 4-Cl-pyridine)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sylvester, Sven O.; Cole, Jacqueline M.; Waddell, Paul G.

    2014-07-24

    Thermally-reversible solid-state linkage SO2 photoisomers of three complexes in the [Ru(NH3)4SO2X]tosylate2 family are captured in their metastable states using photocrystallography, where X = pyridine (1), 3-Cl-pyridine (2) and 4-Cl-pyridine (3). This photoisomerism only exists in the single-crystal form; accordingly, the nature of the crystalline environment surrounding the photo-active species controls its properties. In particular, the structural role of the tosylate anion needs to be understood against possible chemical influences due to varying the trans ligand, X. The photo-excited geometries, photoconversion levels and thermal stabilities of the photoisomers that form in 1-3 are therefore studied. 1 and 2 yield two photo-isomersmore » at 100 K: the O-bound end-on n1-SO2 Page 1 of 32 ACS Paragon Plus Environment The Journal of Physical Chemistry (MS1) configuration and the side-bound n2-SO2 (MS2), while 3 only exhibits the more thermally stable MS2 geometry. The decay kinetics of the MS2 geometry for 1-3 demonstrate that the greater the free volume of the GS SO2 ligand for a given counterion, the greater the MS2 thermal stability. Furthermore, a rationalization is sought for the SO2 phototriggered molecular rotation of the phenyl ring in the tosylate anion; this is selectively observed in 2, manifesting as nanomechanical molecular transduction. This molecular transduction was not observed in 1, despite the presence of the MS1 geometry due to the close intermolecular interactions between the MS1 SO2 and the neighbouring tosylate ion. The decay of this anionic molecular rotor in 2, however, follows a non-traditional decay pathway, as determined by time-resolved crystallographic analysis; this contrasts with the well-behaved first-order kinetic decay of its MS1 SO2 phototrigger.« less

  15. Ru (III) Catalyzed Oxidation of Aliphatic Ketones by N-Bromosuccinimide in Aqueous Acetic Acid: A Kinetic Study

    PubMed Central

    Giridhar Reddy, P.; Ramesh, K.; Shylaja, S.; Rajanna, K. C.; Kandlikar, S.

    2012-01-01

    Kinetics of Ru (III) catalyzed oxidation of aliphatic ketones such as acetone, ethyl methyl ketone, diethyl ketone, iso-butylmethyl ketone by N-bromosuccinimide in the presence of Hg(II) acetate have been studied in aqueous acid medium. The order of [N-bromosuccinimide] was found to be zero both in catalyzed as well as uncatalyzed reactions. However, the order of [ketone] changed from unity to a fractional one in the presence of Ru (III). On the basis of kinetic features, the probable mechanisms are discussed and individual rate parameters evaluated. PMID:22654610

  16. Non-invasive estimation of 10 B-4-borono-L-phenylalanine-derived boron concentration in tumors by PET using 4-borono-2-18 F-fluoro-phenylalanine.

    PubMed

    Yoshimoto, Mitsuyoshi; Honda, Natsuki; Kurihara, Hiroaki; Hiroi, Kenta; Nakamura, Satoshi; Ito, Masashi; Shikano, Naoto; Itami, Jun; Fujii, Hirofumi

    2018-05-01

    In boron neutron capture therapy (BNCT), 10 B-4-borono-L-phenylalanine (BPA) is commonly used as a 10 B carrier. PET using 4-borono-2- 18 F-fluoro-phenylalanine ( 18 F-FBPA PET) has been performed to estimate boron concentration and predict the therapeutic effects of BNCT; however, the association between tumor uptake of 18 F-FBPA and boron concentration in tumors remains unclear. The present study investigated the transport mechanism of 18 F-FBPA and BPA, and evaluated the utility of 18 F-FBPA PET in predicting boron concentration in tumors. The transporter assay revealed that 2-aminobicyclo-(2.2.1)-heptane-2-carboxylic acid, an inhibitor of the L-type amino acid transporter, significantly inhibited 18 F-FBPA and 14 C-4-borono-L-phenylalanine ( 14 C-BPA) uptake in FaDu and LN-229 human cancer cells. 18 F-FBPA uptake strongly correlated with 14 C-BPA uptake in 7 human tumor cell lines (r = .93; P < .01). PET experiments demonstrated that tumor uptake of 18 F-FBPA was independent of the administration method, and uptake of 18 F-FBPA by bolus injection correlated well with BPA uptake by continuous intravenous infusion. The results of this study revealed that evaluating tumor uptake of 18 F-FBPA by PET was useful for estimating 10 B concentration in tumors. © 2018 The Authors.Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.

  17. In vivo PET evaluation in tumour-bearing rats of 2-[ 18F]fluoromethyl- L-phenylalanine as a new potential tracer for molecular imaging of brain and extra-cranial tumours in humans with PET

    NASA Astrophysics Data System (ADS)

    Kersemans, Ken; Bauwens, Matthias; Lahoutte, Tony; Bossuyt, Axel; Mertens, John

    2007-02-01

    The Na +-independent L-type LAT1 amino acid transport system for large and neutral amino acids has been shown to be expressed higher in tumour tissue relative to normal tissue and has been regarded as a key point for the development of new amino acid based tumour tracers for molecular imaging. We developed a new fluorinated phenylalanine analogue, 2-[ 18F]fluoromethyl- L-phenylalanine, considering that the spatial volume of FCH 3 is comparable with that of the iodine atom in 2-I- L-phenylalanine, of which we have proven that it is taken up excellently in tumours by the LAT1 system. The substrate molecule for radiolabeling, Boc-2-bromomethyl- L-phenylalanine- tButylester, was prepared by radical bromination of Boc-2-methyl- L-phenylalanine- tButylester. [ 18F -] for bromine exchange is performed within 3 min in conditions comparable to the [ 18F]FDG synthesis with a radiochemical yield of at least 85%. After deprotection and semi-preparative HPLC purification, the 2-[ 18F]fluoromethyl- L-phenylalanine is recovered n.c.a. (57%) with a high purity and 3.7 MBq were injected into R1M rhabdomyosarcoma tumour-bearing rats. Imaging was performed with a human PET camera from 5 to 45 min p.i. The tumour/background and tumour/blood ratios obtained from PET acquisition were at least 2.5. DUR values for the tumours were at least about 5. Furthermore, a small tumour implanted near a kidney could be well visualized completely separated from this kidney. Moreover in all tumours the "active" tumour tissue can clearly be differentiated from less active tumour tissue. This proves that 2-[ 18F]fluoromethyl- L-phenylalanine has a great potential as a new tracer for specific tumour diagnosis with PET.

  18. Highly efficient and direct heterocyclization of dipyridyl ketone to N,N-bidentate ligands

    NASA Technical Reports Server (NTRS)

    Wang, Jie; Dyers, Leon Jr; Mason, Richard Jr; Amoyaw, Prince; Bu, Xiu R.

    2005-01-01

    [reaction: see text] Reaction of various aromatic aldehydes with 2,2'-dipyridyl ketone and ammonium acetate in hot acetic acid provides ready access to a series of substituted 1-pyridylimidazo[1,5-a]pyridines, a class of ligands possessing an N,N-bidentate feature, in good yields.

  19. Ketone bodies and brain glutamate and GABA metabolism.

    PubMed

    Daikhin, Y; Yudkoff, M

    1998-01-01

    The effects of ketone bodies on brain metabolism of glutamate and GABA were studied in three different systems: synaptosomes, cultured astrocytes and the whole animal. In synaptosomes the addition of either acetoacetate or 3-OH-butyrate was associated with diminished consumption of glutamate via transamination to aspartate and increased formation of labelled GABA from either L-[2H5-2,3,3,4, 4]glutamine or L-[15N]glutamine. There was no effect of ketone bodies on synaptosomal GABA transamination. An increase of total forebrain GABA and a diminution of aspartate was noted when mice were injected intraperitoneally with 3-OH-butyrate. In cultured astrocytes the addition of acetoacetate to the medium was associated with a significantly enhanced rate of citrate production and with a diminution in the rate of conversion of [15N]glutamate to [15N]aspartate. These data are consistent with the hypothesis that the metabolism of ketone bodies to acetyl-CoA results in a diminution of the pool of brain oxaloacetate, which is consumed in the citrate synthetase reaction (oxaloacetate + acetyl-CoA --> citrate). As less oxaloacetate is available to the aspartate aminotransferase reaction, thereby lowering the rate of glutamate transamination, more glutamate becomes accessible to the glutamate decarboxylase pathway, thereby favoring the synthesis of GABA.

  20. Extending the Scope of GTFR Glucosylation Reactions with Tosylated Substrates for Rare Sugars Synthesis.

    PubMed

    Görl, Julian; Possiel, Christian; Sotriffer, Christoph; Seibel, Jürgen

    2017-10-18

    Functionalized rare sugars were synthesized with 2-, 3-, and 6-tosylated glucose derivatives as acceptor substrates by transglucosylation with sucrose and the glucansucrase GTFR from Streptococcus oralis. The 2- and 3-tosylated glucose derivatives yielded the corresponding 1,6-linked disaccharides (isomaltose analogues), whereas the 6-tosylated glucose derivatives resulted in 1,3-linked disaccharides (nigerose analogue) with high regioselectivity in up to 95 % yield. Docking studies provided insight into the binding mode of the acceptors and suggested two different orientations that were responsible for the change in regioselectivity. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Metabolism of DL-(+/-)-phenylalanine by Aspergillus niger.

    PubMed

    Kishore, G; Sugumaran, M; Vaidyanathan, C S

    1976-10-01

    A fungus capable of degrading DL-phenylalanine was isolated from the soil and identified as Aspergillus niger. It was found to metabolize DL-phenylalanine by a new pathway involving 4-hydroxymandelic acid. D-Amino acid oxidase and L-phenylalanine: 2-oxoglutaric acid aminotransferase initiated the degradation of D- and L-phenylalanine, respectively. Both phenylpyruvate oxidase and phenylpyruvate decarboxylase activities could be demonstrated in the cell-free system. Phenylacetate hydroxylase, which required reduced nicotinamide adenine dinucleotide phosphate, converted phenylacetic acid to 2- and 4-hydroxyphenylacetic acid. Although 4-hydroxyphenylacetate was converted to 4-hydroxymandelate, 2-hydroxyphenylacetate was not utilized until the onset of sporulation. During sporulation, it was converted rapidly into homogentisate and oxidized to ring-cleaved products. 4-Hydroxymandelate was degraded to protocatechuate via 4-hydroxybenzoylformate, 4-hydroxybenzaldehyde, and 4-hydroxybenzoate.

  2. Metabolism of DL-(+/-)-phenylalanine by Aspergillus niger.

    PubMed Central

    Kishore, G; Sugumaran, M; Vaidyanathan, C S

    1976-01-01

    A fungus capable of degrading DL-phenylalanine was isolated from the soil and identified as Aspergillus niger. It was found to metabolize DL-phenylalanine by a new pathway involving 4-hydroxymandelic acid. D-Amino acid oxidase and L-phenylalanine: 2-oxoglutaric acid aminotransferase initiated the degradation of D- and L-phenylalanine, respectively. Both phenylpyruvate oxidase and phenylpyruvate decarboxylase activities could be demonstrated in the cell-free system. Phenylacetate hydroxylase, which required reduced nicotinamide adenine dinucleotide phosphate, converted phenylacetic acid to 2- and 4-hydroxyphenylacetic acid. Although 4-hydroxyphenylacetate was converted to 4-hydroxymandelate, 2-hydroxyphenylacetate was not utilized until the onset of sporulation. During sporulation, it was converted rapidly into homogentisate and oxidized to ring-cleaved products. 4-Hydroxymandelate was degraded to protocatechuate via 4-hydroxybenzoylformate, 4-hydroxybenzaldehyde, and 4-hydroxybenzoate. PMID:10273

  3. The influence of cyclomaltooligosaccharides (cyclodextrins) on the enzymatic decomposition of l-phenylalanine catalyzed by phenylalanine ammonia-lyase.

    PubMed

    Gubica, Tomasz; Pełka, Agnieszka; Pałka, Katarzyna; Temeriusz, Andrzej; Kańska, Marianna

    2011-09-27

    Cyclomaltohexaose (α-cyclodextrin) and cyclomaltoheptaose (β-cyclodextrin) as well as their four methyl ether derivatives, that is, hexakis(2,3-di-O-methyl)cyclomaltohexaose, hexakis(2,3,6-tri-O-methyl)cyclomaltohexaose, heptakis(2,3-di-O-methyl)cyclomaltoheptaose, and heptakis(2,3,6-tri-O-methyl)cyclomaltoheptaose were investigated as the additives in the course of enzymatic decomposition of l-phenylalanine catalyzed by phenylalanine ammonia-lyase. Only a few of those additives behaved like classical inhibitors of the enzymatic reaction under investigation because the values of the Michaelis constants that were obtained, as well as the maximum velocity values depended mostly atypically on the concentrations of those additives. In most cases cyclodextrins caused mixed inhibition, both competitive and noncompetitive, but they also acted as activators for selected concentrations. This atypical behaviour of cyclodextrins is caused by three different and independent effects. The inhibitory effect of cyclodextrins is connected with the decrease of substrate concentration and unfavourable influence on the flexibility of the enzyme molecules. On the other hand, the activating effect is connected with the decrease of product concentration (the product is an inhibitor of the enzymatic reaction under investigation). All these effects are caused by the ability of the cyclodextrins to form inclusion complexes. Copyright © 2011 Elsevier Ltd. All rights reserved.

  4. Purification and characterization of an extracellular trypsin-like protease of Fusarium oxysporum var. lini.

    PubMed

    Barata, Ricardo Andrade; Andrade, Milton Hercules Guerra; Rodrigues, Roberta Dias; Castro, Ieso Miranda

    2002-01-01

    An alkaline serineprotease, capable of hydrolyzing Nalpha-benzoyl- dl arginine p-nitroanilide, was secreted by Fusarium oxysporum var. lini grown in the presence of gelatin as the sole nitrogen and carbon source. The protease was purified 65-fold to electrophoretic homogenity from the culture supernatant in a three-step procedure comprising QSepharose chromatography, affinity chromatography, and FPLC on a MonoQ column. SDS-PAGE analysis of the purified protein indicated an estimated molecular mass of 41 kDa. The protease had optimum activity at a reaction temperature of 45 degrees C and showed a rapid decrease of activity at 48 degrees C. The optimum pH was around 8.0. Characterization of the protease showed that Ca2+ and Mg2+ cations increased the activity, which was not inhibited by EDTA or 1,10-phenanthroline. The enzyme activity on Nalpha-benzoyl-DL arginine p-nitroanilide was inhibited by 4-(2-aminoethyl)-benzenesulfonyl fluoride hydrochloride, p-aminobenzamidine dihydrochloride, aprotinin, 3-4 dichloroisocoumarin, and N-tosyl-L-lysine chloromethyl ketone. The enzyme is also inhibited by substrate concentrations higher than 2.5 x 10(-4)M. The protease had a Michaelis-Menten constant of 0.16 mM and a V(max) of 0.60 mumol released product.min(-1).mg(-1) enzyme when assayed in a non-inhibiting substrate concentration. The activity on Nalpha-benzoyl- dl arginine p-nitroanilide was competitively inhibited by p-aminobenzamidine dihydrochoride. A K(i) value of 0.04 mM was obtained.

  5. Construction and application of novel feedback-resistant 3-deoxy-d-arabino-heptulosonate-7-phosphate synthases by engineering the N-terminal domain for L-phenylalanine synthesis.

    PubMed

    Zhang, Chuanzhi; Kang, Zhen; Zhang, Junli; Du, Guocheng; Chen, Jian; Yu, Xiaobin

    2014-04-01

    3-Deoxy-d-arabino-heptulosonate 7-phosphate synthase (DAHP synthase) encoded by aroF is the first enzyme of the shikimate pathway. In the present study, an AroF variant with a deficiency in residue Ile11 (named AroF*) was shown to be insensitive to l-tyrosine. According to three-dimensional structure analysis, nine AroF variants were constructed with truncation of different N-terminal fragments, and overexpression of the variants AroF(Δ(1-9)) , AroF(Δ(1-10)) , AroF(Δ(1-12)) and, in particular, AroF(Δ(1-11)) significantly increased the accumulation of l-phenylalanine (l-Phe). However, the AroG and AroH variants with similar truncations of the N-terminal fragments decreased the production of l-Phe. By co-overexpressing AroF(Δ(1-11)) and PheA(fbr) , the production of l-Phe was increased from 2.36 ± 0.07 g L(-1) (co-overexpression of the wild-type AroF and PheA(fbr) ) to 4.29 ± 0.06 g L(-1) . The novel variant AroF(Δ(1-11)) showed great potential for the production of aromatic amino acids and their derivatives. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  6. Regulation of Phenylalanine Hydroxylase: Conformational Changes Upon Phenylalanine Binding Detected by H/D Exchange and Mass Spectrometry†

    PubMed Central

    Li, Jun; Dangott, Lawrence J.; Fitzpatrick, Paul F.

    2010-01-01

    Phenylalanine acts as an allosteric activator of the tetrahydropterin-dependent enzyme phenylalanine hydroxylase. Hydrogen/deuterium exchange monitored by mass spectrometry has been used to gain insight into local conformational changes accompanying activation of rat phenylalanine hydroxylase by phenylalanine. Peptides in the regulatory and catalytic domains that lie in the interface between these two domains show large increases in the extent of deuterium incorporation from solvent in the presence of phenylalanine. In contrast, the effects of phenylalanine on the exchange kinetics of a mutant enzyme lacking the regulatory domain are limited to peptides surrounding the binding site for the amino acid substrate. These results support a model in which the N-terminus of the protein acts as an inhibitory peptide, with phenylalanine binding causing a conformational change in the regulatory domain that alters the interaction between the catalytic and regulatory domains. PMID:20307070

  7. On the Metabolism of Exogenous Ketones in Humans

    PubMed Central

    Stubbs, Brianna J.; Cox, Pete J.; Evans, Rhys D.; Santer, Peter; Miller, Jack J.; Faull, Olivia K.; Magor-Elliott, Snapper; Hiyama, Satoshi; Stirling, Matthew; Clarke, Kieran

    2017-01-01

    Background and aims: Currently there is considerable interest in ketone metabolism owing to recently reported benefits of ketosis for human health. Traditionally, ketosis has been achieved by following a high-fat, low-carbohydrate “ketogenic” diet, but adherence to such diets can be difficult. An alternative way to increase blood D-β-hydroxybutyrate (D-βHB) concentrations is ketone drinks, but the metabolic effects of exogenous ketones are relatively unknown. Here, healthy human volunteers took part in three randomized metabolic studies of drinks containing a ketone ester (KE); (R)-3-hydroxybutyl (R)-3-hydroxybutyrate, or ketone salts (KS); sodium plus potassium βHB. Methods and Results: In the first study, 15 participants consumed KE or KS drinks that delivered ~12 or ~24 g of βHB. Both drinks elevated blood D-βHB concentrations (D-βHB Cmax: KE 2.8 mM, KS 1.0 mM, P < 0.001), which returned to baseline within 3–4 h. KS drinks were found to contain 50% of the L-βHB isoform, which remained elevated in blood for over 8 h, but was not detectable after 24 h. Urinary excretion of both D-βHB and L-βHB was <1.5% of the total βHB ingested and was in proportion to the blood AUC. D-βHB, but not L-βHB, was slowly converted to breath acetone. The KE drink decreased blood pH by 0.10 and the KS drink increased urinary pH from 5.7 to 8.5. In the second study, the effect of a meal before a KE drink on blood D-βHB concentrations was determined in 16 participants. Food lowered blood D-βHB Cmax by 33% (Fed 2.2 mM, Fasted 3.3 mM, P < 0.001), but did not alter acetoacetate or breath acetone concentrations. All ketone drinks lowered blood glucose, free fatty acid and triglyceride concentrations, and had similar effects on blood electrolytes, which remained normal. In the final study, participants were given KE over 9 h as three drinks (n = 12) or a continuous nasogastric infusion (n = 4) to maintain blood D-βHB concentrations greater than 1 mM. Both drinks and

  8. Structure of the carboxypeptidase B complex with N-sulfamoyl-L-phenylalanine - a transition state analog of non-specific substrate.

    PubMed

    Akparov, Valery; Timofeev, Vladimir; Khaliullin, Ilyas; Švedas, Vytas; Kuranova, Inna

    2018-03-01

    Carboxypeptidase B (EC 3.4.17.2) (CPB) is commonly used in the industrial insulin production and as a template for drug design. However, its ability to discriminate substrates with hydrophobic, hydrophilic, and charged side chains is not well understood. We report structure of CPB complex with a transition state analog N-sulfamoyl-L-phenylalanine solved at 1.74Å. The study provided an insight into structural basis of CPB substrate specificity. Ligand binding is affected by structure-depended conformational changes of Asp255 in S1'-subsite, interactions with Asn144 and Arg145 in C-terminal binding subsite, and Glu270 in the catalytic center. Side chain of the non-specific substrate analog SPhe in comparison with that of specific substrate analog SArg (reported earlier) not only loses favorable electrostatic interactions and two hydrogen bonds with Asp255 and three fixed water molecules, but is forced to be in the unfavorable hydrophilic environment. Thus, Ser207, Gly253, Tyr248, and Asp255 residues play major role in the substrate recognition by S1'-subsite.

  9. Enzymes produced by halotolerant spore-forming gram-positive bacterial strains isolated from a resting habitat (Restinga de Jurubatiba) in Rio de Janeiro, Brazil: focus on proteases.

    PubMed

    D Santos, Anderson Fragoso; Pacheco, Clarissa Almeida; Valle, Roberta D Santos; Seldin, Lucy; D Santos, André Luis Souza

    2014-12-01

    The screening for hydrolases-producing, halotolerant, and spore-forming gram-positive bacteria from the root, rhizosphere, and non-rhizosphere soil of Blutaparon portulacoides, a plant found in the Restinga de Jurubatiba located at the northern region of Rio de Janeiro State, Brazil, resulted in the isolation of 22 strains. These strains were identified as Halobacillus blutaparonensis (n = 2), Oceanobacillus picturae (n = 5), and Oceanobacillus iheyensis (n = 15), and all showed the ability to produce different extracellular enzymes. A total of 20 isolates (90.9 %) showed activity for protease, 5 (22.7 %) for phytase, 3 (13.6 %) for cellulase, and 2 (9.1 %) for amylase. Some bacterial strains were capable of producing three (13.6 %) or two (9.1 %) distinct hydrolytic enzymes. However, no bacterial strain with ability to produce esterase and DNase was observed. The isolate designated M9, belonging to the species H. blutaparonensis, was the best producer of protease and also yielded amylase and phytase. This strain was chosen for further studies regarding its protease activity. The M9 strain produced similar amounts of protease when grown either without or with different NaCl concentrations (from 0.5 to 10 %). A simple inspection of the cell-free culture supernatant by gelatin-sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed the presence of three major alkaline proteases of 40, 50, and 70 kDa, which were fully inhibited by phenylmethylsulfonyl fluoride (PMSF) and tosyl-L-phenylalanine chloromethyl ketone (TPCK) (two classical serine protease inhibitors). The secreted proteases were detected in a wide range of temperature (from 4 to 45 °C) and their hydrolytic activities were stimulated by NaCl (up to 10 %). The serine proteases produced by the M9 strain cleaved gelatin, casein, albumin, and hemoglobin, however, in different extensions. Collectively, these results suggest the potential use of the M9 strain in biotechnological

  10. Laboratory Studies of Aedes aegypti Attraction to Ketones, Sulfides, and Primary Chloroalkanes Tested Alone and in Combination with L-Lactic Acid.

    PubMed

    Bernier, Ulrich R; Kline, Daniel L; Allan, Sandra A; Barnard, Donald R

    2015-03-01

    The attraction of female Aedes aegypti to single compounds and binary compositions containing L-lactic acid and an additional saturated compound from a set of ketones, sulfides, and chloroalkanes was studied using a triple-cage dual-port olfactometer. These chemical classes were studied because of their structural relation to acetone, dimethyl disulfide, and dichloromethane, which have all been reported to synergize attraction to L-lactic acid. Human odors, carbon dioxide, and the binary mixture of L-lactic acid and CO₂served as controls for comparison of attraction responses produced by the binary mixtures. All tested mixtures that contained chloroalkanes attracted mosquitoes at synergistic levels, as did L-lactic acid and CO₂. Synergism was less frequent in mixtures of L-lactic acid with sulfides and ketones; in the case of ketones, synergistic attraction was observed only for L-lactic acid combined with acetone or butanone. Suppression or inhibition of attraction response was observed for combinations that contained ketones of C7-C12 molecular chain length (optimum in the C8-C10 range). This inhibition effect is similar to that observed previously for specific ranges of carboxylic acids, aldehydes, and alcohols.

  11. Molecular Characterization of a Recombinant Zea mays Phenylalanine Ammonia-Lyase (ZmPAL2) and Its Application in trans-Cinnamic Acid Production from L-Phenylalanine.

    PubMed

    Zang, Ying; Jiang, Ting; Cong, Ying; Zheng, Zhaojuan; Ouyang, Jia

    2015-06-01

    Phenylalanine ammonia-lyase (PAL) is one of the most extensively studied enzymes with its crucial role in secondary phenylpropanoid metabolism of plants. Recently, its demand has been increased for aromatic chemical production, but its applications in trans-cinnamic acid production were not much explored. In the present study, a putative PAL gene from Zea mays designated as ZmPAL2 was expressed and characterized in Escherichia coli BL21 (DE3). The recombinant ZmPAL2 exhibited a high PAL activity (7.14 U/mg) and a weak tyrosine ammonia-lyase activity. The optimal temperature of ZmPAL2 was 55 °C, and the thermal stability results showed that about 50 % of enzyme activity remained after a treatment at 60 °C for 6 h. The recombinant ZmPAL2 is a good candidate for the production of trans-cinnamic acid. The vitro conversion indicated that the recombinant ZmPAL2 could effectively catalyze the L-phenylalanine to trans-cinnamic acid, and the trans-cinnamic acid concentration can reach up to 5 g/l.

  12. Interactions in L-phenylalanine/L-leucine/L-glutamic Acid/L-proline + 2 M aqueous NaCl/2 M NaNO3 systems at different temperatures

    NASA Astrophysics Data System (ADS)

    Riyazuddeen, Imran Khan; Afrin, Sadaf

    2012-12-01

    Density (ρ) and speed of sound ( u) in 2 M aqueous NaCl and 2 M NaNO3 solutions of amino acids: L-phenylalanine, L-leucine, L-glutamic acid, and L-proline have been measured for several molal concentrations of amino acids at different temperatures. The ρ and u data have been used to calculate the values of isothermal compressibility and internal pressure at different temperatures. The trends of variations of κ T and P i with an increase in molal concentration of amino acid and temperature have been discussed in terms of solute-solvent and solute-solute interactions in the systems.

  13. A modern view of phenylalanine ammonia lyase.

    PubMed

    MacDonald, M Jason; D'Cunha, Godwin B

    2007-06-01

    Phenylalanine ammonia lyase (PAL; E.C.4.3.1.5), which catalyses the biotransformation of L-phenylalanine to trans-cinnamic acid and ammonia, was first described in 1961 by Koukol and Conn. Since its discovery, much knowledge has been gathered with reference to the enzyme's catabolic role in microorganisms and its importance in the phenyl propanoid pathway of plants. The 3-dimensional structure of the enzyme has been characterized using X-ray crystallography. This has led to a greater understanding of the mechanism of PAL-catalyzed reactions, including the discovery of a recently described cofactor, 3,5-dihydro-5-methyldiene-4H-imidazol-4-one. In the past 3 decades, PAL has gained considerable significance in several clinical, industrial, and biotechnological applications. The reversal of the normal physiological reaction can be effectively employed in the production of optically pure L-phenylalanine, which is a precursor of the noncalorific sweetener aspartame (L-phenylalanyl-L-aspartyl methyl ester). The enzyme's natural ability to break down L-phenylalanine makes PAL a reliable treatment for the genetic condition phenylketonuria. In this mini-review, we discuss prominent details relating to the physiological role of PAL, the mechanism of catalysis, methods of determination and purification, enzyme kinetics, and enzyme activity in nonaqueous media. Two topics of current study on PAL, molecular biology and crystal structure, are also discussed.

  14. L-leucine, L-methionine, and L-phenylalanine share a Na(+)/K (+)-dependent amino acid transporter in shrimp hepatopancreas.

    PubMed

    Duka, Ada; Ahearn, Gregory A

    2013-08-01

    Hepatopancreatic brush border membrane vesicles (BBMV), made from Atlantic White shrimp (Litopenaeus setiferus), were used to characterize the transport properties of (3)H-L-leucine influx by these membrane systems and how other essential amino acids and the cations, sodium and potassium, interact with this transport system. (3)H-L-leucine uptake by BBMV was pH-sensitive and occurred against transient transmembrane concentration gradients in both Na(+)- and K(+)-containing incubation media, suggesting that either cation was capable of providing a driving force for amino acid accumulation. (3)H-L-leucine uptake in NaCl or KCl media were each three times greater in acidic pH (pH 5.5) than in alkaline pH (pH 8.5). The essential amino acid, L-methionine, at 20 mM significantly (p < 0.0001) inhibited the 2-min uptakes of 1 mM (3)H-L-leucine in both Na(+)- and K(+)-containing incubation media. The residual (3)H-L-leucine uptake in the two media were significantly greater than zero (p < 0.001), but not significantly different from each other (p > 0.05) and may represent an L-methionine- and cation-independent transport system. (3)H-L-leucine influxes in both NaCl and KCl incubation media were hyperbolic functions of [L-leucine], following the carrier-mediated Michaelis-Menten equation. In NaCl, (3)H-L-leucine influx displayed a low apparent K M (high affinity) and low apparent J max, while in KCl the transport exhibited a high apparent K M (low affinity) and high apparent J max. L-methionine or L-phenylalanine (7 and 20 mM) were competitive inhibitors of (3)H-L-leucine influxes in both NaCl and KCl media, producing a significant (p < 0.01) increase in (3)H-L-leucine influx K M, but no significant response in (3)H-L-leucine influx J max. Potassium was a competitive inhibitor of sodium co-transport with (3)H-L-leucine, significantly (p < 0.01) increasing (3)H-L-leucine influx K M in the presence of sodium, but having negligible effect on (3)H-L-leucine influx J

  15. Distinct metabolites for photoreactive L-phenylalanine derivatives in Klebsiella sp. CK6 isolated from rhizosphere of a wild dipterocarp sapling.

    PubMed

    Wang, Lei; Hisano, Wataru; Murai, Yuta; Sakurai, Munenori; Muto, Yasuyuki; Ikemoto, Haruka; Okamoto, Masashi; Murotani, Takashi; Isoda, Reika; Kim, Dongyeop; Sakihama, Yasuko; Sitepu, Irnayuli R; Hashidoko, Yasuyuki; Hatanaka, Yasumaru; Hashimoto, Makoto

    2013-07-16

    Photoaffinity labeling is a reliable analytical method for biological functional analysis. Three major photophores--aryl azide, benzophenone and trifluoromethyldiazirine--are utilized in analysis. Photophore-bearing L-phenylalanine derivatives, which are used for biological functional analysis, were inoculated into a Klebsiella sp. isolated from the rhizosphere of a wild dipterocarp sapling in Central Kalimantan, Indonesia, under nitrogen-limiting conditions. The proportions of metabolites were quite distinct for each photophore. These results indicated that photophores affected substrate recognition in rhizobacterial metabolic pathways, and differential photoaffinity labeling could be achieved using different photophore-containing L-phenylalanine derivatives.

  16. Microbial L-phenylalanine ammonia-lyase. Purification, subunit structure and kinetic properties of the enzyme from Rhizoctonia solani.

    PubMed Central

    Kalghatgi, K K; Subba Rao, P V

    1975-01-01

    1. Phenylalanine ammonia-lyase (EC 4.3.1.5) was purified to homogeneity from the acetone-dried powders of the mycelial felts of the plant pathogenic fungus Rhizoctonia solani. 2. A useful modification in protamine sulphate treatment to get substantial purification of the enzyme in a single-step is described. 3. The purified enzyme shows bisubstrate activity towards L-phenylalanine and L-tyrosine. 4. It is sensitive to carbonyl reagents and the inhibition is not reversed by gel filtration. 5. The molecular weight of the enzyme as determined by Sephadex G-200 chromatography and sucrose-density-gradient centrifugation is around 330000. 6. The enzyme is made up of two pairs of unidentical subunits, with a molecular weight of 70000 (alpha) and 90000 (beta) respectively. 7. Studies on initial velocity versus substrate concentration have shown significant deviations from Michaelis-Menten kinetics. 8. The double-reciprocal plots are biphasic (concave downwards) and Hofstee plots show a curvilinear pattern. 9. The apparent Km value increases from 0.18 mM to as high as 5.0 mM with the increase in the concentration of the substrate and during this process the Vmax, increases by 2-2.5-fold. 10. The value of Hill coefficient is 0.5. 11. Steady-state rates of phenylalanine ammonia-lyase reaction in the presence of inhibitors like D-phenylalanine, cinnamic, p-coumaric, caffeic, dihydrocaffeic and phenylpyruvic acid have shown that only one molecule of each type of inhibitor binds to a molecule of the enzyme. These observations suggest the involvement of negative homotropic interactions in phenylalanine ammonia-lyase. 12. The enzyme could not be desensitized by treatment with HgCl2, p-chloromercuribenzoic acid or by repeated freezing and thawing. PMID:1191266

  17. Improved synthesis of no-carrier-added p-[124I]iodo-L-phenylalanine and p-[131I]iodo-L-phenylalanine for nuclear medicine applications in malignant gliomas.

    PubMed

    Israel, Ina; Brandau, Wolfgang; Farmakis, Georgios; Samnick, Samuel

    2008-04-01

    This work describes the synthesis and the tumor affinity testing of no-carrier-added (n.c.a.) p-[(124)I]iodo-L-phenyalanine ([(124)I]IPA) and n.c.a. p-[(131)I]iodo-l-phenyalanine ([(131)I]IPA) as radiopharmaceuticals for imaging brain tumors with PET and for radionuclid-based therapy, respectively. Parameters for labeling were optimized with regard to the amount of precursor, temperature and time. Thereafter, n.c.a. [(124)I]IPA and n.c.a. [(131)I]IPA were investigated in rat F98 glioma and in primary human A1207 and HOM-T3868 glioblastoma cells in vitro, followed by an in vivo evaluation in CD1 nu/nu mice engrafted with human glioblastoma. No-carrier-added [(124)I]IPA and n.c.a. [(131)I]IPA were obtained in 90+/-6% radiochemical yield and >99% radiochemical purity by iododestannylation of N-Boc-4-(tri-n-butylstannyl)-L-phenylalanine methylester in the presence of chloramine-T, followed by hydrolysis of the protecting groups. The total synthesis time, including the HPLC separation and pharmacological formulation, was less than 60 min and compatible with a clinical routine production. Both amino acid tracers accumulated intensively in rat and in human glioma cells. The radioactivity incorporation in tumor cells following a 15-min incubation at 37 degrees C/pH 7.4 varied from 25% to 42% of the total loaded activity per 10(6) tumor cells (296-540 cpm/1000 cells). Inhibition experiments confirmed that n.c.a. [(124)I]IPA and n.c.a. [(131)I]IPA were taken up into tumor by the sodium-independent L- and ASC-type transporters. Biodistribution and whole-body imaging by a gamma-camera and a PET scanner demonstrated a high targeting level and a prolonged retention of n.c.a. [(124)I]IPA and n.c.a. [(131)I]IPA within the xenotransplanted human glioblastoma and a primarily renal excretion. However, an accurate delineation of the tumors in mice was not possible by our imaging systems. Radioactivity accumulation in the thyroid and in the stomach as a secondary indication of

  18. 21 CFR 173.70 - Chloromethylated aminated styrene-divinylbenzene resin.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Chloromethylated aminated styrene-divinylbenzene resin. 173.70 Section 173.70 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN CONSUMPTION Polymer...

  19. Nuclear magnetic resonance studies of phenylalanine analog interactions with normal and sicklen hemoglobin

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lee, Y.H.

    Several phenylalanine derivatives have been found to inhibit the gelation of deoxygenated sickle hemoglobin (deoxy HbS). Proton and /sup 19/F-NMR techniques were used to monitor the interaction of selected phenylalanine derivatives with the Hb molecule by using fluorine containing phenylalanine derivatives, Hb labeled at the ..beta..93 position with N-(2,2,2-trifluoroethyl) iodoacetamide (IA-F/sub 3/), and by monitoring the relaxation rates of the C2 and C4 histidine protons. The results show that the /sup 19/F spin-spin relaxation times of L-phenylalanin-4-fluorobenzylamide (PheNBz1-F), which has a deoxy HbS antigelling activity comparable to that of the amino acid, tryptophan, are affected much more strongly by interactionmore » with Hb than are those of glycin-4-fluorobenzylamide (GlyNBz1-F). In contrast, it is shown that N-(2,2,5,5-tetramethylpyrrolidin-1-oxy-3-carboxyl)-L-phenylalanine t-butyl ester (SL-Phe) exhibits specific binding to Hb, and an antigelling activity more than two orders of magnitude greater than that of phenylalanine. These results indicate that the fluorine nuclei strongly influenced by the presence of spin label nitroxide are located in a conformation within a few angstroms of the SL-Phe binding site. Proton NMR relaxation measurements of the C2 and C4 proton resonances from the ..beta..2, 4b143 and ..beta..146 histidine residues show significant and selective effects from the binding of SL-Phe to Hb, indicating that the SL-Phe binding site must be close to the side chains of these three residues. The strong antigelation activity of SL-Phe suggests that this binding site may be one of the intermolecular contact sites of importance to the deoxy HbS aggregation process.« less

  20. A study of carbobenzoxy-D-phenylalanine-L-phenylalanine-glycine, an inhibitor of membrane fusion, in phospholipid bilayers with multinuclear magnetic resonance.

    PubMed

    Dentino, A R; Westerman, P W; Yeagle, P L

    1995-05-04

    The anti-viral and membrane fusion inhibitor, carbobenzoxy-D-phenylalanine-L-phenylalanine-glycine (ZfFG), was studied in phospholipid bilayers, where earlier studies had indicated this peptide functioned. Multinuclear magnetic resonance (NMR) studies were performed with isotopically labeled peptide. A peptide labeled in the glycine carboxyl with 13C was synthesized, and the isotropic 13C-NMR chemical shift of that carbon was measured as a function of pH. A pKa of 3.6 for the carboxyl was determined from the peptide bound to a phosphatidylcholine bilayer. ZfFG inhibits the formation by sonication of highly curved, small unilamellar vesicles. Experiments as a function of pH revealed that this ability of ZfFG was governed by a pKa of 3.7. Therefore the protonation state of the carboxyl of ZfFG appeared to regulate the effectiveness of this anti-viral peptide at destabilizing highly curved phospholipid assemblies. Such destabilization had previously been discovered to be related to the mechanism of the anti-fusion and anti-viral activity of this peptide. The location of the carboxyl of ZfFG in the membrane was probed with paramagnetic relaxation enhancement of the 13C spin lattice relaxation of the carboxyl carbon in the glycine of ZfFG (enriched in 13C). Results suggested that this carboxyl is at or above the surface of the phospholipid bilayer. The dynamics of the molecule in the membrane were examined with 2H-NMR studies of ZfFG, deuterated in the alpha-carbon protons of the glycine. When ZfFG was bound to membranes of phosphatidylcholine, a sharp 2H-NMR spectral component was observed, consistent with a disordering of the glycine methylene segment of the peptide. When ZfFG was bound to N-methyl dioleoylphosphatidylethanolamine (N-methyl DOPE) bilayers at temperatures below 30 degrees C, a large quadrupole splitting was observed. These results suggest that ZfFG likely inhibits membrane fusion from the surface of the lipid bilayer, but not by forming a tight

  1. Two-Step Production of Phenylpyruvic Acid from L-Phenylalanine by Growing and Resting Cells of Engineered Escherichia coli: Process Optimization and Kinetics Modeling.

    PubMed

    Hou, Ying; Hossain, Gazi Sakir; Li, Jianghua; Shin, Hyun-Dong; Liu, Long; Du, Guocheng; Chen, Jian

    2016-01-01

    Phenylpyruvic acid (PPA) is widely used in the pharmaceutical, food, and chemical industries. Here, a two-step bioconversion process, involving growing and resting cells, was established to produce PPA from l-phenylalanine using the engineered Escherichia coli constructed previously. First, the biotransformation conditions for growing cells were optimized (l-phenylalanine concentration 20.0 g·L-1, temperature 35°C) and a two-stage temperature control strategy (keep 20°C for 12 h and increase the temperature to 35°C until the end of biotransformation) was performed. The biotransformation conditions for resting cells were then optimized in 3-L bioreactor and the optimized conditions were as follows: agitation speed 500 rpm, aeration rate 1.5 vvm, and l-phenylalanine concentration 30 g·L-1. The total maximal production (mass conversion rate) reached 29.8 ± 2.1 g·L-1 (99.3%) and 75.1 ± 2.5 g·L-1 (93.9%) in the flask and 3-L bioreactor, respectively. Finally, a kinetic model was established, and it was revealed that the substrate and product inhibition were the main limiting factors for resting cell biotransformation.

  2. On the asymmetric adsorption of phenylalanine enantiomers by kaolin.

    NASA Technical Reports Server (NTRS)

    Bonner, W. A.; Flores, J.

    1973-01-01

    The attempt is described to verify a recent report that kaolin adsorbs D- and L-phenylalanine enantiomers to different extents from aqueous solutions at both pH 5.8 and pH 2. No evidence whatsoever could be found for the differential adsorption of D- versus L-phenylalanine by kaolin from either pH 6 or pH 2 solutions.

  3. Two groups of phenylalanine biosynthetic operon leader peptides genes: a high level of apparently incidental frameshifting in decoding Escherichia coli pheL

    PubMed Central

    Gurvich, Olga L.; Näsvall, S. Joakim; Baranov, Pavel V.; Björk, Glenn R.; Atkins, John F.

    2011-01-01

    The bacterial pheL gene encodes the leader peptide for the phenylalanine biosynthetic operon. Translation of pheL mRNA controls transcription attenuation and, consequently, expression of the downstream pheA gene. Fifty-three unique pheL genes have been identified in sequenced genomes of the gamma subdivision. There are two groups of pheL genes, both of which are short and contain a run(s) of phenylalanine codons at an internal position. One group is somewhat diverse and features different termination and 5′-flanking codons. The other group, mostly restricted to Enterobacteria and including Escherichia coli pheL, has a conserved nucleotide sequence that ends with UUC_CCC_UGA. When these three codons in E. coli pheL mRNA are in the ribosomal E-, P- and A-sites, there is an unusually high level, 15%, of +1 ribosomal frameshifting due to features of the nascent peptide sequence that include the penultimate phenylalanine. This level increases to 60% with a natural, heterologous, nascent peptide stimulator. Nevertheless, studies with different tRNAPro mutants in Salmonella enterica suggest that frameshifting at the end of pheL does not influence expression of the downstream pheA. This finding of incidental, rather than utilized, frameshifting is cautionary for other studies of programmed frameshifting. PMID:21177642

  4. Synthesis of CuPF6 -(S)-BINAP loaded resin and its enantioselectivity toward phenylalanine enantiomers.

    PubMed

    Liu, Xiong; Zhou, Wenqi; Xu, Longqi

    2017-09-01

    A type of resin-anchored CuPF 6 -(S)-BINAP was synthesized and identified. The PS-CuPF 6 -(S)-BINAP resin was used to adsorb the phenylalanine enantiomers. The results showed that the adsorption capacity of PS-CuPF 6 -(S)-BINAP resin toward L-phenylalanine was higher than that of resin toward D-phenylalanine. PS-CuPF 6 -(S)-BINAP resin exhibited good enantioselectivity toward L-phenylalanine and D-phenylalanine. The influence of phenylalanine concentration, pH, adsorption time, and temperature on the enantioselectivity of the resin were investigated. The results showed that the enantioselectivity of the resin increased with increasing the phenylalanine concentration, pH, and adsorption time, while it decreased with an increase in temperature. The causes for these influences are discussed. The highest enantioselectivity (α = 2.81) was obtained when the condition of phenylalanine concentration was 0.05 mmol/mL, pH was 8, adsorption time was 12 h, and temperature 5°C. The desorption test for removing D/L-phenylalanine on PS-CuPF 6 -(S)-BINAP resin was also investigated. The desorption ratios of D-phenylalanine and L-phenylalanine at pH of 1 were 95.7% and 94.3%, respectively. This result indicated that the PS-CuPF 6 -(S)-BINAP resin could be regenerated by shaking with an acidic solution. The reusability of the PS-CuPF 6 -(S)-BINAP resin was also assessed and the resin exhibited considerable reusability. © 2017 Wiley Periodicals, Inc.

  5. 40 CFR 721.5560 - Formaldehyde, polymer with (chloromethyl) oxirane and phenol, reaction products with 6H-dibenz[c...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... (chloromethyl) oxirane and phenol, reaction products with 6H-dibenz[c,e][1,2]oxaphosphorin-6-oxide. 721.5560... Substances § 721.5560 Formaldehyde, polymer with (chloromethyl) oxirane and phenol, reaction products with 6H... phenol, reaction products with 6H-dibenz[c,e][1,2]oxaphosphorin-6-oxide. (PMN P-00-991; CAS No. 300371-38...

  6. 40 CFR 721.5560 - Formaldehyde, polymer with (chloromethyl) oxirane and phenol, reaction products with 6H-dibenz[c...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... (chloromethyl) oxirane and phenol, reaction products with 6H-dibenz[c,e][1,2]oxaphosphorin-6-oxide. 721.5560... Substances § 721.5560 Formaldehyde, polymer with (chloromethyl) oxirane and phenol, reaction products with 6H... phenol, reaction products with 6H-dibenz[c,e][1,2]oxaphosphorin-6-oxide. (PMN P-00-991; CAS No. 300371-38...

  7. The measurement of muscle protein synthesis in broilers with a flooding dose technique: use of 15N-labelled phenylalanine, GC-MS and GC-C-IRMS.

    PubMed

    Dänicke, S; Böttcher, W; Simon, O; Jeroch, H

    2001-01-01

    An experiment was carried out to measure fractional muscle protein synthesis rates (k(s)) in broilers with injection of a flooding dose of phenylalanine (1 ml/100 g body weight of 150 mM phenylalanine; 38 atom percent excess (APE) [15N]phenylalanine). K(s) was calculated from the [15N] enrichment in phenylalanine of tissue-free and protein-bound phenylalanine using both gas chromatography mass spectrometry (GC-MS) and gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS) for measurements after a 10 min isotope incorporation period. The tertiary-butyldimethylsilyl (t-BDMS) derivatives of phenylalanine were used for gas chromatographic separation in both systems. GC-MS and GC-C-IRMS were calibrated for a range of 7 to 37 [15N]APE and 0 to 0.62 [15N]APE, respectively, and for sample sizes of 0.45 to 4.5 nmol phenylalanine and 7 to 40 nmol phenylalanine, respectively. Reproducibility of standards as a measure of precision varied from 0.06 to 0.29 [15N]APE and from 0.0004 to 0.0018 [15N]APE in GC-MS and GC-C-IRMS, respectively. K(s) was measured in the m. pectoralis major of broilers fed rye based diets (56%) which were provided either unsupplemented (-) or supplemented (+) with an enzyme preparation containing xylanase. K(s) in breast muscles was significantly increased from 21.8%/d to 23.9%/d due to enzyme supplementation. It can be concluded from the study that the measurement of protein synthesis in broilers with the flooding dose technique can be carried out by using [15N]phenylalanine, GC-MS and GC-C-IRMS.

  8. Simultaneous and selective decarboxylation of L-serine and deamination of L-phenylalanine in an amino acid mixture--a means of separating amino acids for synthesizing biobased chemicals.

    PubMed

    Teng, Yinglai; Scott, Elinor L; Witte-van Dijk, Susan C M; Sanders, Johan P M

    2016-01-25

    Amino acids (AAs) obtained from the hydrolysis of biomass-derived proteins are interesting feedstocks for the chemical industry. They can be prepared from the byproduct of biofuel production and agricultural wastes. They are rich in functionalities needed in petrochemicals, providing the opportunity to save energy, reagents, and process steps. However, their separation is required before they can be applied for further applications. Electrodialysis (ED) is a promising separation method, but its efficiency needs to be improved when separating AAs with similar isoelectric points. Thus, specific conversions are required to form product with different charges. Here we studied the enzymatic conversions which can be used as a means to aid the ED separation of neutral AAs. A model mixture containing L-serine, L-phenylalanine and L-methionine was used. The reactions of L-serine decarboxylase and L-phenylalanine ammonia-lyase were employed to specifically convert serine and phenylalanine into ethanolamine and trans-cinnamic acid. At the isoelectric point of methionine (pH 5.74), the charge of ethanolamine and trans-cinnamic acid are +1 and -1, therefore facilitating potential separation into three different streams by electrodialysis. Here the enzyme kinetics, specificity, inhibition and the operational stabilities were studied, showing that both enzymes can be applied simultaneously to aid the ED separation of neutral AAs. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Treatment of attention deficit disorder with DL-phenylalanine.

    PubMed

    Wood, D R; Reimherr, F W; Wender, P H

    1985-09-01

    Nineteen patients meeting the criteria for attention deficit disorder, residual type (adult hyperactivity), were given a 2-week double-blind crossover of DL-phenylalanine versus placebo. Thirteen subjects completed the study; the mean global rating of improvement approached significance as compared with placebo. A significant improvement was noted on mood and mood lability. The phenylalanine responders were then continued on open drug, but lost all positive benefits within 3 months. A later open trial of L-phenylalanine produced no clinical effect.

  10. [Preparation of L-phenylalanine chiral ligand-exchange chromatographic stationary phase by atom transfer radical polymerization and resolution of racemates].

    PubMed

    Sun, Yang; Xu, Fei; Gong, Bolin

    2011-09-01

    A novel stationary phase was synthesized for chiral ligand-exchange chromatography via atom transfer radical polymerization (ATRP). Glycidyl methacrylate (GMA) was grafted onto the surface of the silica by ATRP using bromoisobutyryl bromide as an initiator, and the organic metal compound formed in the CuCl/2,2'-bipyridine(Bpy) system as a catalyst at room temperature. The chiral stationary phase was then synthesized by grafting L-phenylalanine on the surface of the silica. The stationary phase was characterized by means of elementary analysis and evaluated in detail to determine its separability. The amount of L-phenylalanine on the surface of silica was calculated to be 4.32 mg/m2. The results showed that the good enantioseparations of some DL-amino acids were obtained using ligand-exchange chromatography on the synthesized chiral stationary phase (50 degrees C) with 0.05 mol/L KH2PO4 and 0.1 mmol/L Cu(Ac)2 solution (pH 4.5) as the mobile phase at a flow rate of 1.0 mL/min and a wavelength of 223 nm. The influences of the mobile phase pH, concentration of Cu (II), and temperature of column on the resolution of DL-amino acids by ligand-exchange chromatography were investigated. The results showed that these conditions could affect the resolution of racemates. Compared with the column prepared by radical method using L-phenylalanine directly bonded onto the surface of the silica, the synthesized stationary phase showed a better separation ability, and the DL-aspartic acids and DL-asparagines could be separated at baseline.

  11. Genetic engineering of Escherichia coli to improve L-phenylalanine production.

    PubMed

    Liu, Yongfei; Xu, Yiran; Ding, Dongqin; Wen, Jianping; Zhu, Beiwei; Zhang, Dawei

    2018-01-30

    L-phenylalanine (L-Phe) is an essential amino acid for mammals and applications expand into human health and nutritional products. In this study, a system level engineering was conducted to enhance L-Phe biosynthesis in Escherichia coli. We inactivated the PTS system and recruited glucose uptake via combinatorial modulation of galP and glk to increase PEP supply in the Xllp01 strain. In addition, the HTH domain of the transcription factor TyrR was engineered to decrease the repression on the transcriptional levels of L-Phe pathway enzymes. Finally, proteomics analysis demonstrated the third step of the SHIK pathway (catalyzed via AroD) as the rate-limiting step for L-Phe production. After optimization of the aroD promoter strength, the titer of L-Phe increased by 13.3%. Analysis of the transcriptional level of genes involved in the central metabolic pathways and L-Phe biosynthesis via RT-PCR showed that the recombinant L-Phe producer exhibited a great capability in the glucose utilization and precursor (PEP and E4P) generation. Via systems level engineering, the L-Phe titer of Xllp21 strain reached 72.9 g/L in a 5 L fermenter under the non-optimized fermentation conditions, which was 1.62-times that of the original strain Xllp01. The metabolic engineering strategy reported here can be broadly employed for developing genetically defined organisms for the efficient production of other aromatic amino acids and derived compounds.

  12. The effects of plant growth regulators and L-phenylalanine on phenolic compounds of sweet basil.

    PubMed

    Koca, Nülüfer; Karaman, Şengül

    2015-01-01

    The effects of methyl jasmonate (MeJA), spermine (Spm), epibrassinolide (EBL) and l-phenylalanine on sweet basil (Ocimum basilicum L.) were studied to determine the amount of phenolic compounds and enzymatic activity of phenylalanine ammonia-lyase (PAL). Total phenolic and total flavonoid contents of sweet basils were determined by a spectrophotometer, and individual phenolic compounds and activity of PAL were analysed by HPLC/UV. The highest total phenolic (6.72 mg GAE/g) and total flavonoid contents (0.92 mg QE/g) obtained from 1.0 mM Spm+MeJA application. Rosmarinic acid (RA) and caffeic acid contents significantly enhanced after the applications but no such differences observed in chicoric acid content or PAL activity. RA was the main phenolic acid in all samples and its concentration varied from 1.04 to 2.70 mg/gFW. As a result the combinations of Spm+MeJA and EBL+MeJA can induce secondary metabolites effectively and those interactions play important role in the production of phytochemicals in plants. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Ketone isosteres of 2-N-acetamidosugars as substrates for metabolic cell surface engineering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hang, Howard C.; Bertozzi, Carolyn R.

    2000-08-22

    Novel chemical reactivity can be engendered on cell surfaces by the metabolic incorporation of unnatural sugars into cell surface glycoconjuagtes. 2-N-Acetamido sugars such as GalNAc and GlcNAc are abundant components of cell surface glycoconjugates, and hence attractive targets for metabolic cell surface engineering. Here we report (1) the synthesis of isosteric analogs bearing a ketone group in place of the N-acetamido group, and (2) evaluation of their metabolic incorporation into mammalian cell surface glycans. A ketone isostere of GalNAc was metabolized by CHO cells through the salvage pathway and delivered to O-linked glycoproteins on the cell surface. Its residence atmore » the core position of O-linked glycans is suggested by studies with a-benzyl GalNAc, an inhibitor of O-linked oligosaccharide extension. A mutant CHO cell line lacking endogenous UDP-GalNAc demonstrated enhanced metabolism of the GalNAc analog, suggesting that competition with native intermediates might limits enzymatic transformation in mammalian cells. A ketone isostere of GlcNAc could not be detected on CHO or human cell surfaces after incubation. Thus, the enzymes in the GlcNAc salvage pathway might be less permissive of unnatural substrates than those comprising the GalNAc salvage pathway. Alternatively, high levels of endogenous GlcNAc derivatives might compete with the ketone isostere and prevent its incorporation into oligosaccharides.« less

  14. Trypsin from the digestive system of carp Cirrhinus mrigala: purification, characterization and its potential application.

    PubMed

    Khangembam, Bronson Kumar; Chakrabarti, Rina

    2015-05-15

    Trypsin was purified 35.64-fold with 4.97% recovery from the viscera of carp Cirrhinus mrigala (mrigal) by ammonium sulfate precipitation, ion exchange and affinity chromatography. The purified enzyme was active at a wide range of pH (7.0-9.2) and temperature (10-50°C). The purified enzyme exhibited high thermal stability up to 50°C for 1h. The enzyme activity was stabilized by Ca(+2) (2mM) up to 7h at 40°C. The Km and kcat values of purified enzyme were 0.0672 mM and 92.09/s/mM, respectively. Soybean trypsin inhibitor and phenylmethylsulphonylflouride completely inhibited the enzyme activity. The specific inhibitor of trypsin, N-α-p-tosyl-L-lysine chloromethyl ketone inhibited 99.67% activity. Na(+), K(+) and Li(+) inhibited 20.99 ± 5.25%, 16.53 ± 4.80% and 18.99 ± 1.42% of enzyme activity, respectively. Divalent ions Mg(+2), Zn(+2), Co(+2), Hg(+2) and Cd(+2) inhibited 21.61 ± 2.22%, 31.62 ± 1.78%, 31.62 ± 1.96%, 85.68 ± 1.51% and 47.95 ± 2.13% enzyme activity, respectively. SDS-PAGE showed that the molecular mass of purified enzyme was 21.7 kDa. MALDI-TOF study showed a peptide sequence of AFCGGSLVNENKMHSAGHCYKSRIQV at the N-Terminal. This sequence recorded 76-84% identity with trypsin from Thunnus thynnus and other fish species. This confirmed that the purified protein was trypsin. The purified enzyme has potential applications in detergent and food industry because of its thermal stability and alkaline nature. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Metal-Ion-Mediated Supramolecular Chirality of l-Phenylalanine Based Hydrogels.

    PubMed

    Wang, Fang; Feng, Chuan-Liang

    2018-05-14

    For chiral hydrogels and related applications, one of the critical issues is how to control the chirality of supramolecular systems in an efficient way, including easy operation, efficient transfer of chirality, and so on. Herein, supramolecular chirality of l-phenylalanine based hydrogels can be effectively controlled by using a broad range of metal ions. The degree of twisting (twist pitch) and the diameter of the chiral nanostructures can also be efficiently regulated. These are ascribed to the synergic effect of hydrogen bonding and metal ion coordination. This study may develop a method to design a new class of electronically, optically, and biologically active materials. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Amino acid-functionalized multi-walled carbon nanotubes for improving compatibility with chiral poly(amide-ester-imide) containing L-phenylalanine and L-tyrosine linkages

    NASA Astrophysics Data System (ADS)

    Abdolmaleki, Amir; Mallakpour, Shadpour; Borandeh, Sedigheh

    2013-12-01

    Amino acid functionalized multi-walled carbon nanotubes (f-MWCNTs)/poly(amide-ester-imide) (PAEI) composites were fabricated by solution mixing method. Proper functionalization and mixing strategy of MWCNTs provides the best opportunity for better distribution and bonding of nanoparticles to the polymer matrix. MWCNTs have been chemically modified with L-phenylalanine to improve their compatibility with L-phenylalanine based PAEI. Field emission scanning electron microscopy micrographs of composite revealed that f-MWCNTs made a good interaction with polymer chains by wrapping the polymer around them, and transmission electron microscopy results confirmed well dispersion with nano size of f-MWCNTs in the polymer matrix. In addition, thermal analysis showed good enhancement in thermal properties of composites compared to pure polymer. Thermal stability of the composites containing f-MWCNTs was enhanced due to their good dispersion and improved interfacial interaction between the amino acid based PAEI matrix and f-MWCNTs.

  17. Phenylalanine containing hydrophobic nanospheres for antibody purification.

    PubMed

    Türkmen, Deniz; Denizli, Adil; Oztürk, Nevra; Akgöl, Sinan; Elkak, Assem

    2008-01-01

    In this study, novel hydrophobic nanospheres with an average size of 158 nm utilizing N-methacryloyl-(L)-phenylalanine methyl ester (MAPA) as a hydrophobic monomer were produced by surfactant free emulsion polymerization of 2-hydroxyethyl methacrylate (HEMA) and MAPA conducted in an aqueous dispersion medium. MAPA was synthesized using methacryloyl chloride and L-phenylalanine methyl ester. Specific surface area of the nonporous nanospheres was found to be 1874 m2/g. Poly(HEMA-MAPA) nanospheres were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Average particle size, size distribution, and surface charge measurements were also performed. Elemental analysis of MAPA for nitrogen was estimated as 0.42 mmol/g polymer. Then, poly(HEMA-MAPA) nanospheres were used in the adsorption of immunoglobulin G (IgG) in batch system. Higher adsorption values (780 mg/g) were obtained when the poly (HEMA-MAPA) nanospheres were used from both aqueous solutions and human plasma. The adsorption phenomena appeared to follow a typical Langmuir isotherm. It was observed that IgG could be repeatedly adsorbed and desorbed without significant loss in adsorption amount. These findings show considerable promise for this material as a hydrophobic support in industrial processes.

  18. Effect of N-[(trans-4-isopropylcyclohexyl)-carbonyl]-D-phenylalanine on nutrient catabolism in rat pancreatic islets.

    PubMed

    Malaisse, W J; Sener, A

    1998-09-01

    1. The effect of N-[(trans-4-isopropylcyclohexyl)-carbonyl]-D-phenylalanine (A-4166) on nutrient metabolism was investigated in isolated rat pancreatic islets. 2. At a 10-microM concentration, the meglitinide analogue caused a modest increase in 14CO2 output from islets prelabeled with L-[U-14C]glutamine but failed to affect D-[5-3H]glucose utilization, D-[U-14C]glucose oxidation and conversion into 14C-labeled acidic metabolites and amino acids, L[1-14C]leucine and L-[U-14C]leucine oxidation, the generation of 2-ketoisocaproate and further acidic metabolites from the branched-chain amino acid and the production of 14CO2 by islets prelabeled with [U-14C]palmitate. 3. These findings indicate that the insulinotropic action of A-4166 is not attributable to any sizeable increase in the metabolism of exogenous or endogenous nutrients.

  19. Influence of reagents reacting with metal, thiol and amino sites of catalytic activity and l-phenylalanine inhibition of rat intestinal alkaline phosphatase

    PubMed Central

    Fishman, William H.; Ghosh, Nimai K.

    1967-01-01

    1. Studies on the inactivation of rat intestinal alkaline phosphatase by several metal-binding agents, namely EDTA, 8-hydroxyquinoline, pyridine-2,6-dicarboxylic acid, αα′-bipyridyl, o-phenanthroline and sodium cyanide, indicated the functional role of a metal, probably zinc, in the catalysis. The metal ligands lowered stereospecific uncompetitive inhibition of the enzyme by l-phenylalanine by an extent that paralleled the decline in enzyme activity. 2. The thiol reagents p-hydroxymercuribenzoate, iodoacetamide and iodine inactivated rat intestinal phosphatase. The enzyme could be protected from inactivation by either cysteine or substrate. The l-phenylalanine inhibition remained unchanged only in the presence of moderately inactivating concentrations of the thiol reagents. 3. Inactivation of the enzyme by the amino-group-blocking reagent, O-methylisourea, provided ample evidence for the participation in the catalysis of the ∈-amino group of lysine. At the same time, l-phenylalanine inhibition remained unaltered even when the enzyme was strongly inactivated. This ∈-amino-group-blocked enzyme exhibited no change in migration in starch gel, in contrast with enzyme treated with acetic anhydride, formaldehyde or succinic anhydride. The Michaelis constant of the enzyme was enhanced by such modifications, but the optimum pH remained the same. 4. d-Phenylalanine acted as a competitive or `co-operative' activator for intestinal alkaline phosphatase after it had been modified by acetylation. PMID:16742542

  20. Two-Step Production of Phenylpyruvic Acid from L-Phenylalanine by Growing and Resting Cells of Engineered Escherichia coli: Process Optimization and Kinetics Modeling

    PubMed Central

    Hou, Ying; Hossain, Gazi Sakir; Li, Jianghua; Shin, Hyun-dong; Liu, Long; Du, Guocheng; Chen, Jian

    2016-01-01

    Phenylpyruvic acid (PPA) is widely used in the pharmaceutical, food, and chemical industries. Here, a two-step bioconversion process, involving growing and resting cells, was established to produce PPA from l-phenylalanine using the engineered Escherichia coli constructed previously. First, the biotransformation conditions for growing cells were optimized (l-phenylalanine concentration 20.0 g·L−1, temperature 35°C) and a two-stage temperature control strategy (keep 20°C for 12 h and increase the temperature to 35°C until the end of biotransformation) was performed. The biotransformation conditions for resting cells were then optimized in 3-L bioreactor and the optimized conditions were as follows: agitation speed 500 rpm, aeration rate 1.5 vvm, and l-phenylalanine concentration 30 g·L−1. The total maximal production (mass conversion rate) reached 29.8 ± 2.1 g·L−1 (99.3%) and 75.1 ± 2.5 g·L−1 (93.9%) in the flask and 3-L bioreactor, respectively. Finally, a kinetic model was established, and it was revealed that the substrate and product inhibition were the main limiting factors for resting cell biotransformation. PMID:27851793

  1. Oral and topical L-phenylalanine, clobetasol propionate, and UVA/sunlight--a new study for the treatment of vitiligo.

    PubMed

    Camacho, Francisco; Mazuecos, José

    2002-09-01

    Vitiligo is a hypopigmented skin condition that usually requires a combination of treatment options. To demonstrate the effectiveness of topical and oral L-phenylalanine in combination with light plus 0.025% clobetasol propionate at night. We have performed an open trial on a group of 70 patients with evolutive vitiligo. Participants were treated with oral (100 mg/Kg/day) and topical (gel at 10%) L-phenylalanine, exposed to sunlight (spring-summer) or UVA lamps (autumn-winter), and given 0.025% clobetasol propionate at night. All patients were revisited every 6 months while in the study, with a maximum of 4 revisits. Biochemical studies were performed at the beginning of the treatment and at each revisit. Overall, 90.9% of participants showed improvement, with 68.5% of patients achieving an improvement of 75% or more. This 75% improvement rate was reached 87.9% of the time on the face, 60.4% on the trunk, and 54.6% on the limbs. However, there was a moderate response to the treatment in patients with focal and segmental vitiligo. There was a slight additional improvement in patients receiving UVA lamp light. No biochemical abnormalities were found in any patients. L-phenylalanine in combination with 0.025% clobetasol propionate and sunlight during sunny months or UVA lamps in winter, appears to improve evolutive vitiligo without side effects, and therefore is especially recommended on the face or for children.

  2. L-Phenylalanine preloading reduces the (10)B(n, α)(7)Li dose to the normal brain by inhibiting the uptake of boronophenylalanine in boron neutron capture therapy for brain tumours.

    PubMed

    Watanabe, Tsubasa; Tanaka, Hiroki; Fukutani, Satoshi; Suzuki, Minoru; Hiraoka, Masahiro; Ono, Koji

    2016-01-01

    Boron neutron capture therapy (BNCT) is a cellular-level particle radiation therapy that combines the selective delivery of boron compounds to tumour tissue with neutron irradiation. Previously, high doses of one of the boron compounds used for BNCT, L-BPA, were found to reduce the boron-derived irradiation dose to the central nervous system. However, injection with a high dose of L-BPA is not feasible in clinical settings. We aimed to find an alternative method to improve the therapeutic efficacy of this therapy. We examined the effects of oral preloading with various analogues of L-BPA in a xenograft tumour model and found that high-dose L-phenylalanine reduced the accumulation of L-BPA in the normal brain relative to tumour tissue. As a result, the maximum irradiation dose in the normal brain was 19.2% lower in the L-phenylalanine group relative to the control group. This study provides a simple strategy to improve the therapeutic efficacy of conventional boron compounds for BNCT for brain tumours and the possibility to widen the indication of BNCT to various kinds of other tumours. Copyright © 2015. Published by Elsevier Ireland Ltd.

  3. Synthesis, characterization, and anticancer activity of a series of ketone-N(4)-substituted thiosemicarbazones and their ruthenium(II) arene complexes.

    PubMed

    Su, Wei; Qian, Quanquan; Li, Peiyuan; Lei, Xiaolin; Xiao, Qi; Huang, Shan; Huang, Chusheng; Cui, Jianguo

    2013-11-04

    A series of ketone-N(4)-substituted thiosemicarbazone (TSC) compounds (L1-L9) and their corresponding [(η(6)-p-cymene)Ru(II)(TSC)Cl](+/0) complexes (1-9) were synthesized and characterized by NMR, IR, elemental analysis, and HR-ESI-mass spectrometry. The molecular structures of L4, L9, 1-6, and 9 were determined by single-crystal X-ray diffraction analysis. The compounds were further evaluated for their in vitro antiproliferative activities against the SGC-7901 human gastric cancer, BEL-7404 human liver cancer, and HEK-293T noncancerous cell lines. Furthermore, the interactions of the compounds with DNA were followed by electrophoretic mobility spectrometry studies.

  4. Silica gel promotes reductions of aldehydes and ketones by N-heterocyclic carbene boranes.

    PubMed

    Taniguchi, Tsuyoshi; Curran, Dennis P

    2012-09-07

    N-Heterocyclic carbene boranes (NHC-boranes) such as 1,3-dimethylimidazol-2-ylidine trihydridoborane (diMe-Imd-BH(3)) serve as practical hydride donors for the reduction of aldehydes and ketones in the presence of silica gel. Primary and secondary alcohols are formed in good yields under ambient conditions. Aldehydes are selectively reduced in the presence of ketones. One, two, or even all three of the boron hydrides can be transferred. The process is attractive because all the components are stable and easy to handle and because both the reaction and isolation procedures are convenient.

  5. Integration of E. coli aroG-pheA tandem genes into Corynebacterium glutamicum tyrA locus and its effect on L-phenylalanine biosynthesis

    PubMed Central

    Liu, Dong-Xin; Fan, Chang-Sheng; Tao, Ju-Hong; Liang, Guo-Xin; Gao, Shan-E; Wang, Hai-Jiao; Li, Xin; Song, Da-Xin

    2004-01-01

    AIM: To study the effect of integration of tandem aroG-pheA genes into the tyrA locus of Corynebacterium glutamicum (C. glutamicum) on the production of L-phenylalanine. METHODS: By nitrosoguanidine mutagenesis, five p-fluorophenylalanine (FP)-resistant mutants of C.glutamicum FP were selected. The tyrA gene encoding prephenate dehydrogenase (PDH) of C.glutamicum was amplified by polymerase chain reaction (PCR) and cloned on the plasmid pPR. Kanamycin resistance gene (Km) and the PBF-aroG-pheA-T (GA) fragment of pGA were inserted into tyrA gene to form targeting vectors pTK and pTGAK, respectively. Then, they were transformed into C.glutamicum FP respectively by electroporation. Cultures were screened by a medium containing kanamycin and detected by PCR and phenotype analysis. The transformed strains were used for L-phenylalanine fermentation and enzyme assays. RESULTS: Engineering strains of C.glutamicum (Tyr-) were obtained. Compared with the original strain, the transformed strain C. glutamicum GAK was observed to have the highest elevation of L-phenylalanine production by a 1.71-fold, and 2.9-, 3.36-, and 3.0-fold in enzyme activities of chorismate mutase, prephenate dehydratase and 3-deoxy-D-arabinoheptulosonate-7-phosphate synthase, respectively. CONCLUSION: Integration of tandem aroG-pheA genes into tyrA locus of C. glutamicum chromosome can disrupt tyrA gene and increase the yield of L-phenylalanine production. PMID:15534933

  6. Bovine pancreatic trypsin inhibitor immobilized onto sepharose as a new strategy to purify a thermostable alkaline peptidase from cobia (Rachycentron canadum) processing waste.

    PubMed

    França, Renata Cristina da Penha; Assis, Caio Rodrigo Dias; Santos, Juliana Ferreira; Torquato, Ricardo José Soares; Tanaka, Aparecida Sadae; Hirata, Izaura Yoshico; Assis, Diego Magno; Juliano, Maria Aparecida; Cavalli, Ronaldo Olivera; Carvalho, Luiz Bezerra de; Bezerra, Ranilson Souza

    2016-10-15

    A thermostable alkaline peptidase was purified from the processing waste of cobia (Rachycentron canadum) using bovine pancreatic trypsin inhibitor (BPTI) immobilized onto Sepharose. The purified enzyme had an apparent molecular mass of 24kDa by both sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and mass spectrometry. Its optimal temperature and pH were 50°C and 8.5, respectively. The enzyme was thermostable until 55°C and its activity was strongly inhibited by the classic trypsin inhibitors N-ρ-tosyl-l-lysine chloromethyl ketone (TLCK) and benzamidine. BPTI column allowed at least 15 assays without loss of efficacy. The purified enzyme was identified as a trypsin and the N-terminal amino acid sequence of this trypsin was IVGGYECTPHSQAHQVSLNSGYHFC, which was highly homologous to trypsin from cold water fish species. Using Nα-benzoyl-dl-arginine ρ-nitroanilide hydrochloride (BApNA) as substrate, the apparent km value of the purified trypsin was 0.38mM, kcat value was 3.14s(-1), and kcat/km was 8.26s(-1)mM(-1). The catalytic proficiency of the purified enzyme was 2.75×10(12)M(-1) showing higher affinity for the substrate at the transition state than other fish trypsin. The activation energy (AE) of the BApNA hydrolysis catalyzed by this enzyme was estimated to be 11.93kcalmol(-1) while the resulting rate enhancement of this reaction was found to be approximately in a range from 10(9) to 10(10)-fold evidencing its efficiency in comparison to other trypsin. This new purification strategy showed to be appropriate to obtain an alkaline peptidase from cobia processing waste with high purification degree. According with N-terminal homology and kinetic parameters, R. canadum trypsin may gathers desirable properties of psychrophilic and thermostable enzymes. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Herbivore-induced phenylacetonitrile is biosynthesized from de novo-synthesized L-phenylalanine in the giant knotweed, Fallopia sachalinensis.

    PubMed

    Noge, Koji; Tamogami, Shigeru

    2013-06-19

    Plants emit a series of characteristic volatile blends when damaged by insect feeding. Phenylacetonitrile is one of the volatiles from the leaves of the giant knotweed, Fallopia sachalinensis, infested by the Japanese beetle, Popillia japonica, or treated with exogenous airborne methyl jasmonate (MeJA). We examined the precursor of the nitrile and its origin in this system. L-Phenylalanine was determined to be a precursor of the nitrile in F. sachalinensis leaves, and the phenylalanine was also induced by beetle feeding and MeJA treatment. We also found that exogenous MeJA enhanced the biosynthesis of several amino acids in F. sachalinensis leaves. Copyright © 2013 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  8. Molecular complexes of L-phenylalanine with substituted 1,4-benzoquinones in aqueous medium: Spectral and theoretical investigations

    NASA Astrophysics Data System (ADS)

    Ganesh, K.; El-Mossalamy, E. H.; Satheshkumar, A.; Balraj, C.; Elango, K. P.

    2013-12-01

    Various spectral techniques such as UV-Vis, FT-IR, and fluorescence have been employed to investigate the charge transfer interaction of L-phenylalanine (LPA) with substituted 1,4-benzoquinones (MQ1-4). Kinetic and thermodynamic properties of the complexes were determined in aqueous medium at physiological condition (pH = 7). The interaction of MQ1-4 with L-phenylalanine (LPA) was found to proceed through the formation of donor-acceptor complex, yielding a radical anion. The stoichiometry of the complexes was determined by Jobs continuous variation method and was found to be 1:1 in all the cases. Fluorescence quenching studies showed that the interaction between the donor and the acceptors is spontaneous. The results indicated that the progressive replacement of chlorine atom (-I effect) by methoxy group (+M effect) in the quinone decreased the electron acceptor property of the quinone. The order of the experimentally measured association constant of these complexes was well supported by DFT/B3LYP calculations.

  9. The cathepsin B inhibitor z-FA-CMK induces cell death in leukemic T cells via oxidative stress.

    PubMed

    Liow, K Y; Chow, Sek C

    2018-01-01

    The cathepsin B inhibitor benzyloxycarbonyl-phenylalanine-alanine-chloromethyl ketone (z-FA-CMK) was recently found to induce apoptosis at low concentrations in Jurkat T cells, while at higher concentrations, the cells die of necrosis. In the present study, we showed that z-FA-CMK readily depletes intracellular glutathione (GSH) with a concomitant increase in reactive oxygen species (ROS) generation. The toxicity of z-FA-CMK in Jurkat T cells was completely abrogated by N-acetylcysteine (NAC), suggesting that the toxicity mediated by z-FA-CMK is due to oxidative stress. We found that L-buthionine sulfoximine (BSO) which depletes intracellular GSH through the inhibition of GSH biosynthesis in Jurkat T cells did not promote ROS increase or induce cell death. However, NAC was still able to block z-FA-CMK toxicity in Jurkat T cells in the presence of BSO, indicating that the protective effect of NAC does not involve GSH biosynthesis. This is further corroborated by the protective effect of the non-metabolically active D-cysteine on z-FA-CMK toxicity. Furthermore, in BSO-treated cells, z-FA-CMK-induced ROS increased which remains unchanged, suggesting that the depletion of GSH and increase in ROS generation mediated by z-FA-CMK may be two separate events. Collectively, our results demonstrated that z-FA-CMK toxicity is mediated by oxidative stress through the increase in ROS generation.

  10. A Bio-Catalytic Approach to Aliphatic Ketones

    PubMed Central

    Xiong, Mingyong; Deng, Jin; Woodruff, Adam P.; Zhu, Minshan; Zhou, Jun; Park, Sun Wook; Li, Hui; Fu, Yao; Zhang, Kechun

    2012-01-01

    Depleting oil reserves and growing environmental concerns have necessitated the development of sustainable processes to fuels and chemicals. Here we have developed a general metabolic platform in E. coli to biosynthesize carboxylic acids. By engineering selectivity of 2-ketoacid decarboxylases and screening for promiscuous aldehyde dehydrogenases, synthetic pathways were constructed to produce both C5 and C6 acids. In particular, the production of isovaleric acid reached 32 g/L (0.22 g/g glucose yield), which is 58% of the theoretical yield. Furthermore, we have developed solid base catalysts to efficiently ketonize the bio-derived carboxylic acids such as isovaleric acid and isocaproic acid into high volume industrial ketones: methyl isobutyl ketone (MIBK, yield 84%), diisobutyl ketone (DIBK, yield 66%) and methyl isoamyl ketone (MIAK, yield 81%). This hybrid “Bio-Catalytic conversion” approach provides a general strategy to manufacture aliphatic ketones, and represents an alternate route to expanding the repertoire of renewable chemicals. PMID:22416247

  11. A bio-catalytic approach to aliphatic ketones.

    PubMed

    Xiong, Mingyong; Deng, Jin; Woodruff, Adam P; Zhu, Minshan; Zhou, Jun; Park, Sun Wook; Li, Hui; Fu, Yao; Zhang, Kechun

    2012-01-01

    Depleting oil reserves and growing environmental concerns have necessitated the development of sustainable processes to fuels and chemicals. Here we have developed a general metabolic platform in E. coli to biosynthesize carboxylic acids. By engineering selectivity of 2-ketoacid decarboxylases and screening for promiscuous aldehyde dehydrogenases, synthetic pathways were constructed to produce both C5 and C6 acids. In particular, the production of isovaleric acid reached 32 g/L (0.22 g/g glucose yield), which is 58% of the theoretical yield. Furthermore, we have developed solid base catalysts to efficiently ketonize the bio-derived carboxylic acids such as isovaleric acid and isocaproic acid into high volume industrial ketones: methyl isobutyl ketone (MIBK, yield 84%), diisobutyl ketone (DIBK, yield 66%) and methyl isoamyl ketone (MIAK, yield 81%). This hybrid "Bio-Catalytic conversion" approach provides a general strategy to manufacture aliphatic ketones, and represents an alternate route to expanding the repertoire of renewable chemicals.

  12. The Amino Acid Specificity for Activation of Phenylalanine Hydroxylase Matches the Specificity for Stabilization of Regulatory Domain Dimers

    PubMed Central

    2016-01-01

    Liver phenylalanine hydroxylase is allosterically activated by phenylalanine. The structural changes that accompany activation have not been identified, but recent studies of the effects of phenylalanine on the isolated regulatory domain of the enzyme support a model in which phenylalanine binding promotes regulatory domain dimerization. Such a model predicts that compounds that stabilize the regulatory domain dimer will also activate the enzyme. Nuclear magnetic resonance spectroscopy and analytical ultracentrifugation were used to determine the ability of different amino acids and phenylalanine analogues to stabilize the regulatory domain dimer. The abilities of these compounds to activate the enzyme were analyzed by measuring their effects on the fluorescence change that accompanies activation and on the activity directly. At concentrations of 10–50 mM, d-phenylalanine, l-methionine, l-norleucine, and (S)-2-amino-3-phenyl-1-propanol were able to activate the enzyme to the same extent as 1 mM l-phenylalanine. Lower levels of activation were seen with l-4-aminophenylalanine, l-leucine, l-isoleucine, and 3-phenylpropionate. The ability of these compounds to stabilize the regulatory domain dimer agreed with their ability to activate the enzyme. These results support a model in which allosteric activation of phenylalanine hydroxylase is linked to dimerization of regulatory domains. PMID:26252467

  13. A ketogenic diet increases transport and oxidation of ketone bodies in RG2 and 9L gliomas without affecting tumor growth.

    PubMed

    De Feyter, Henk M; Behar, Kevin L; Rao, Jyotsna U; Madden-Hennessey, Kirby; Ip, Kevan L; Hyder, Fahmeed; Drewes, Lester R; Geschwind, Jean-François; de Graaf, Robin A; Rothman, Douglas L

    2016-08-01

    The dependence of tumor cells, particularly those originating in the brain, on glucose is the target of the ketogenic diet, which creates a plasma nutrient profile similar to fasting: increased levels of ketone bodies and reduced plasma glucose concentrations. The use of ketogenic diets has been of particular interest for therapy in brain tumors, which reportedly lack the ability to oxidize ketone bodies and therefore would be starved during ketosis. Because studies assessing the tumors' ability to oxidize ketone bodies are lacking, we investigated in vivo the extent of ketone body oxidation in 2 rodent glioma models. Ketone body oxidation was studied using (13)C MR spectroscopy in combination with infusion of a (13)C-labeled ketone body (beta-hydroxybutyrate) in RG2 and 9L glioma models. The level of ketone body oxidation was compared with nontumorous cortical brain tissue. The level of (13)C-beta-hydroxybutyrate oxidation in 2 rat glioma models was similar to that of contralateral brain. In addition, when glioma-bearing animals were fed a ketogenic diet, the ketone body monocarboxylate transporter was upregulated, facilitating uptake and oxidation of ketone bodies in the gliomas. These results demonstrate that rat gliomas can oxidize ketone bodies and indicate upregulation of ketone body transport when fed a ketogenic diet. Our findings contradict the hypothesis that brain tumors are metabolically inflexible and show the need for additional research on the use of ketogenic diets as therapy targeting brain tumor metabolism. © The Author(s) 2016. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  14. Protein conformation by EPR spectroscopy using gadolinium tags clicked to genetically encoded p-azido-L-phenylalanine.

    PubMed

    Abdelkader, E H; Feintuch, A; Yao, X; Adams, L A; Aurelio, L; Graham, B; Goldfarb, D; Otting, G

    2015-11-14

    Quantitative cysteine-independent ligation of a Gd(3+) tag to genetically encoded p-azido-L-phenylalanine via Cu(I)-catalyzed click chemistry is shown to deliver an exceptionally powerful tool for Gd(3+)-Gd(3+) distance measurements by double electron-electron resonance (DEER) experiments, as the position of the Gd(3+) ion relative to the protein can be predicted with high accuracy.

  15. Ketones urine test

    MedlinePlus

    Ketone bodies - urine; Urine ketones; Ketoacidosis - urine ketones test; Diabetic ketoacidosis - urine ketones test ... Urine ketones are usually measured as a "spot test." This is available in a test kit that ...

  16. Engineering ..beta..-Oxidation in Yarrowia lipolytica for Methyl Ketone Production

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sanchez i Nogue, Violeta; Ramirez, Kelsey J; Singer, Christine

    Medium- and long-chain methyl ketones are fatty acid-derived compounds that can be used as biofuel blending agents, flavors and fragrances. However, their large-scale production from sustainable feedstocks is currently limited due to the lack of robust microbial biocatalysts. The oleaginous yeast Yarrowia lipolytica is a promising biorefinery platform strain for the production of methyl ketones from renewable lignocellulosic biomass due to its natively high flux towards fatty acid biosynthesis. In this study, we report the metabolic engineering of Y. lipolytica to produce long- and very long-chain methyl ketones. Truncation of peroxisomal ..beta..-oxidation by chromosomal deletion of pot1 resulted in themore » biosynthesis of saturated, mono-, and diunsaturated methyl ketones in the C13-C23 range. Additional overexpression and peroxisomal targeting of a heterologous bacterial methyl ketone biosynthesis pathway yielded an initial titer of 151.5 mg/L of saturated methyl ketones. Dissolved oxygen concentrations in the cultures were found to substantially impact cell morphology and methyl ketone biosynthesis. Bioreactor cultivation under optimized conditions resulted in a titer of 314.8 mg/L of total methyl ketones, representing more than a 6000-fold increase over the parental strain. This work highlights the potential of Y. lipolytica to serve as chassis organism for the biosynthesis of acyl-thioester derived long- and very long-chain methyl ketones.« less

  17. Ketones prevent synaptic dysfunction induced by mitochondrial respiratory complex inhibitors

    PubMed Central

    Kim, Do Young; Vallejo, Johana; Rho, Jong M

    2010-01-01

    Abstract Ketones have previously shown beneficial effects in models of neurodegenerative disorders, particularly against associated mitochondrial dysfunction and cognitive impairment. However, evidence of a synaptic protective effect of ketones remains lacking. We tested the effects of ketones on synaptic impairment induced by mitochondrial respiratory complex (MRC) inhibitors using electrophysiological, reactive oxygen species (ROS) imaging and biochemical techniques. MRC inhibitors dose-dependently suppressed both population spike (PS) and field potential amplitudes in the CA1 hippocampus. Pre-treatment with ketones strongly prevented changes in the PS, whereas partial protection was seen in the field potential. Rotenone (Rot; 100 nmol/L), a MRC I inhibitor, suppressed synaptic function without altering ROS levels and PS depression by Rot was unaffected by antioxidants. In contrast, antioxidant-induced PS recovery against the MRC II inhibitor 3-nitropropionic acid (3-NP; 1 mmol/L) was similar to the synaptic protective effects of ketones. Ketones also suppressed ROS generation induced by 3-NP. Finally, ketones reversed the decreases in ATP levels caused by Rot and 3-NP. In summary, our data demonstrate that ketones can preserve synaptic function in CA1 hippocampus induced by MRC dysfunction, likely through an antioxidant action and enhanced ATP generation. PMID:20374433

  18. Efficient preparation of enantiopure D-phenylalanine through asymmetric resolution using immobilized phenylalanine ammonia-lyase from Rhodotorula glutinis JN-1 in a recirculating packed-bed reactor.

    PubMed

    Zhu, Longbao; Zhou, Li; Huang, Nan; Cui, Wenjing; Liu, Zhongmei; Xiao, Ke; Zhou, Zhemin

    2014-01-01

    An efficient enzymatic process was developed to produce optically pure D-phenylalanine through asymmetric resolution of the racemic DL-phenylalanine using immobilized phenylalanine ammonia-lyase (RgPAL) from Rhodotorula glutinis JN-1. RgPAL was immobilized on a modified mesoporous silica support (MCM-41-NH-GA). The resulting MCM-41-NH-GA-RgPAL showed high activity and stability. The resolution efficiency using MCM-41-NH-GA-RgPAL in a recirculating packed-bed reactor (RPBR) was higher than that in a stirred-tank reactor. Under optimal operational conditions, the volumetric conversion rate of L-phenylalanine and the productivity of D-phenylalanine reached 96.7 mM h⁻¹ and 0.32 g L⁻¹ h⁻¹, respectively. The optical purity (eeD) of D-phenylalanine exceeded 99%. The RPBR ran continuously for 16 batches, the conversion ratio did not decrease. The reactor was scaled up 25-fold, and the productivity of D-phenylalanine (eeD>99%) in the scaled-up reactor reached 7.2 g L⁻¹ h⁻¹. These results suggest that the resolution process is an alternative method to produce highly pure D-phenylalanine.

  19. Efficient Preparation of Enantiopure D-Phenylalanine through Asymmetric Resolution Using Immobilized Phenylalanine Ammonia-Lyase from Rhodotorula glutinis JN-1 in a Recirculating Packed-Bed Reactor

    PubMed Central

    Huang, Nan; Cui, Wenjing; Liu, Zhongmei; Xiao, Ke; Zhou, Zhemin

    2014-01-01

    An efficient enzymatic process was developed to produce optically pure D-phenylalanine through asymmetric resolution of the racemic DL-phenylalanine using immobilized phenylalanine ammonia-lyase (RgPAL) from Rhodotorula glutinis JN-1. RgPAL was immobilized on a modified mesoporous silica support (MCM-41-NH-GA). The resulting MCM-41-NH-GA-RgPAL showed high activity and stability. The resolution efficiency using MCM-41-NH-GA-RgPAL in a recirculating packed-bed reactor (RPBR) was higher than that in a stirred-tank reactor. Under optimal operational conditions, the volumetric conversion rate of L-phenylalanine and the productivity of D-phenylalanine reached 96.7 mM h−1 and 0.32 g L−1 h−1, respectively. The optical purity (ee D) of D-phenylalanine exceeded 99%. The RPBR ran continuously for 16 batches, the conversion ratio did not decrease. The reactor was scaled up 25-fold, and the productivity of D-phenylalanine (ee D>99%) in the scaled-up reactor reached 7.2 g L−1 h−1. These results suggest that the resolution process is an alternative method to produce highly pure D-phenylalanine. PMID:25268937

  20. Solvent-Tuned Self-Assembled Nanostructures of Chiral l/d-Phenylalanine Derivatives of Protoporphyrin IX

    PubMed Central

    Bobe, Mr Sharad R; Al Kobaisi, Mohammad; Bhosale, Sheshanath V; Bhosale, Sidhanath V

    2015-01-01

    Protoporphyrin IX is a naturally occurring amphiphilic porphyrin with a rigid hydrophobic nonpolar core and two polar propionic acid substitutions on the porphyrin ring. This molecule can be modified on the hydrophilic group, which can lead to strengthened π–π-stacking and spontaneous self-assembly into novel nanostructures. Herein, we use l- phenylalanine and d-phenylalanine to modify protoporphyrin IX, and use the two derivatives for solvophobic-controlled self-assembly. Both derivatives possess two important features: 1) the aromatic core of the porphyrin for dispersive interactions and 2) a chiral amino acid to maximize the influence of chirality on selfassembly. These derivatives lead to the formation of a variety of nanostructure morphologies, such as spheres, nanofibers, lamellar structures, and thread-like and spherical shells. Solution-based self-assembly was determined by UV/Vis, fluorescence, and circular dichroism spectroscopy, and the formed nanostructures were characterized by scanning electron microscopy (SEM). Such engineered porphyrin derivatives could have potential applications in energy transport and storage, supramolecular chemistry, materials science, and medicine. PMID:26478848

  1. Solvent-Tuned Self-Assembled Nanostructures of Chiral l/d-Phenylalanine Derivatives of Protoporphyrin IX.

    PubMed

    Bobe, Mr Sharad R; Al Kobaisi, Mohammad; Bhosale, Sheshanath V; Bhosale, Sidhanath V

    2015-08-01

    Protoporphyrin IX is a naturally occurring amphiphilic porphyrin with a rigid hydrophobic nonpolar core and two polar propionic acid substitutions on the porphyrin ring. This molecule can be modified on the hydrophilic group, which can lead to strengthened π-π-stacking and spontaneous self-assembly into novel nanostructures. Herein, we use l- phenylalanine and d-phenylalanine to modify protoporphyrin IX, and use the two derivatives for solvophobic-controlled self-assembly. Both derivatives possess two important features: 1) the aromatic core of the porphyrin for dispersive interactions and 2) a chiral amino acid to maximize the influence of chirality on selfassembly. These derivatives lead to the formation of a variety of nanostructure morphologies, such as spheres, nanofibers, lamellar structures, and thread-like and spherical shells. Solution-based self-assembly was determined by UV/Vis, fluorescence, and circular dichroism spectroscopy, and the formed nanostructures were characterized by scanning electron microscopy (SEM). Such engineered porphyrin derivatives could have potential applications in energy transport and storage, supramolecular chemistry, materials science, and medicine.

  2. Laboratory studies of Aedes aegypti (L.) attraction to ketones, sulfides and primary chloroalkanes tested alone and in combination with l-lactic acid

    USDA-ARS?s Scientific Manuscript database

    The attraction of female Aedes aegypti to single compounds and binary compositions comprised of L-lactic acid and an additional saturated compound from a set of ketones, sulfides, and chloroalkanes was studied using a triple-cage dual-port olfactometer. These chemical classes were studied because o...

  3. Molecular complexes of l-phenylalanine with substituted 1,4-benzoquinones in aqueous medium: spectral and theoretical investigations.

    PubMed

    Ganesh, K; El-Mossalamy, E H; Satheshkumar, A; Balraj, C; Elango, K P

    2013-12-01

    Various spectral techniques such as UV-Vis, FT-IR, and fluorescence have been employed to investigate the charge transfer interaction of L-phenylalanine (LPA) with substituted 1,4-benzoquinones (MQ(1-4)). Kinetic and thermodynamic properties of the complexes were determined in aqueous medium at physiological condition (pH=7). The interaction of MQ(1-4) with L-phenylalanine (LPA) was found to proceed through the formation of donor-acceptor complex, yielding a radical anion. The stoichiometry of the complexes was determined by Jobs continuous variation method and was found to be 1:1 in all the cases. Fluorescence quenching studies showed that the interaction between the donor and the acceptors is spontaneous. The results indicated that the progressive replacement of chlorine atom (-I effect) by methoxy group (+M effect) in the quinone decreased the electron acceptor property of the quinone. The order of the experimentally measured association constant of these complexes was well supported by DFT/B3LYP calculations. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. A different approach to treatment of phenylketonuria: Phenylalanine degradation with recombinant phenylalanine ammonia lyase

    PubMed Central

    Sarkissian, Christineh N.; Shao, Zhongqi; Blain, Françoise; Peevers, Rosalie; Su, Hongsheng; Heft, Robert; Chang, Thomas M. S.; Scriver, Charles R.

    1999-01-01

    Phenylketonuria (PKU), with its associated hyperphenylalaninemia (HPA) and mental retardation, is a classic genetic disease and the first to have an identified chemical cause of impaired cognitive development. Treatment from birth with a low phenylalanine diet largely prevents the deviant cognitive phenotype by ameliorating HPA and is recognized as one of the first effective treatments of a genetic disease. However, compliance with dietary treatment is difficult and when it is for life, as now recommended by an internationally used set of guidelines, is probably unrealistic. Herein we describe experiments on a mouse model using another modality for treatment of PKU compatible with better compliance using ancillary phenylalanine ammonia lyase (PAL, EC 4.3.1.5) to degrade phenylalanine, the harmful nutrient in PKU; in this treatment, PAL acts as a substitute for the enzyme phenylalanine monooxygenase (EC 1.14.16.1), which is deficient in PKU. PAL, a robust enzyme without need for a cofactor, converts phenylalanine to trans-cinnamic acid, a harmless metabolite. We describe (i) an efficient recombinant approach to produce PAL enzyme, (ii) testing of PAL in orthologous N-ethyl-N′-nitrosourea (ENU) mutant mouse strains with HPA, and (iii) proofs of principle (PAL reduces HPA)—both pharmacologic (with a clear dose–response effect vs. HPA after PAL injection) and physiologic (protected enteral PAL is significantly effective vs. HPA). These findings open another way to facilitate treatment of this classic genetic disease. PMID:10051643

  5. PKU: high plasma phenylalanine concentrations are associated with increased prevalence of mood swings.

    PubMed

    Anjema, Karen; van Rijn, Margreet; Verkerk, Paul H; Burgerhof, Johannes G M; Heiner-Fokkema, M Rebecca; van Spronsen, Francjan J

    2011-11-01

    In phenylketonuria, knowledge about the relation between behavior and plasma phenylalanine is scarce. The aim of this study was to determine whether high phenylalanine is associated with disturbed behavior noticed by the patient and or close environment (parents or partners). 48 early treated PKU patients (median age 8.5, range 0-35 years) participated (median phenylalanine concentration in total sample 277 (range 89-1171) μmol/l; and in patients <12 years 238 (range 89-521) μmol/l). After sending blood samples, patients or close environment were interviewed with a standardized questionnaire whether they noticed hyperactivity, annoying behavior, mood swings and introvert or extravert behavior. The interviewer as well as the respondents were blinded with regard to the phenylalanine concentration. Patients reported less deviant behavior compared to close environment. Mood swings were positively associated with phenylalanine concentrations in the total group (P=0.039) and patients <12 years (P=0.042). The relationships between temporary high phenylalanine concentrations and hyperactivity, annoying behavior, introvert and extravert behavior were not statistically significant. there is a positive association between phenylalanine concentrations and mood swings. Copyright © 2011 Elsevier Inc. All rights reserved.

  6. Isolation of an N-acetyl-DL-phenylalanine beta-naphthyl esterase from rabbit peritoneal polymorphonuclear leukocytes.

    PubMed

    Tsung, P; Kegeles, S W; Showell, H J; Becker, E L

    1975-09-22

    An N-acetyl-DL-phenylalanine beta-naphthyl esterase has been purified 26-fold from rabbit peritoneal polymorphonuclear leukocytes. The purified enzyme was inhibited by 10(-7) M p-nitrophenylethyl-5-chloropentylphosphonate. The apparent Km for hydrolysis of N-acetyl-DL-phenylalanine beta-naphthyl ester is 71 muM. Optimal reaction rates were observed at pH 6-8. No divalent cation requirement for the activation of the enzyme activity was observed. The esterase activity was neither inhibited nor stimulated by bacterial factor, complement component C5a, guanosine 3',5'-monophosphate (cyclic GMP) and adenosine 3',5'-monophosphate (cyclic AMP) which are attractants or repellents for polymorphonuclear leukocytes. High chemotactic activity was observed in the partially purified fraction of the enzyme. The chemotactic activity, like the enzyme activity, was completely inhibited by 10(-7) M phosphonate.

  7. D- and L-[123I]-2-I-phenylalanine show a long tumour retention compared with D- and L-[123I]-2-I-tyrosine in R1M rhabdomyosarcoma tumour-bearing Wag/Rij rats.

    PubMed

    Bauwens, Matthias; Lahoutte, Tony; Kersemans, Ken; Caveliers, Vicky; Bossuyt, Axel; Mertens, John

    2007-07-01

    The aim of this study was the comparison of the tumour uptake and the long-term retention of [(123)I]-2-I-L-phenylalanine and [(123)I]-2-I-D-phenylalanine with those of [(123)I]-2-I-L-tyrosine and [(123)I]-2-I-D-tyrosine in R1M rhabdomyosarcoma tumour-bearing rats. The biodistribution of the radioactivity as a function of time in R1M tumour-bearing rats was measured by planar gamma camera imaging (dynamic and static). If dissection was applied, the activity in the tumours and tissues of interest was measured by gamma counting. [(123)I]-2-iodo-L-phenylalanine, [(123)I]-2-iodo-D-phenylalaine, [(123)I]-2-I-L-tyrosine showed a considerable tumour uptake reaching a maximum between 10 and 30 min. At 30 min p.i. the differential uptake ratio values of this uptake were, respectively, 2.1, 2.3, 2.5 and 1.7. The activity in the tumour was shown to be related to a tumour cell uptake and not to an increased blood pool activity. All the tracers showed a clearance from the blood to the bladder without renal retention. At longer times both L- and D- [(123)I]-2-I-tyrosine were cleared for a large part from the tumours and the body. [(123)I]-2-I-L-Phe and [(123)I]-2-I-D-Phe showed a considerable and equal retention in the tumours: as compared with 0.5 h, 91% at 24 h and 80% at 48 h. This was related to the longer retention of activity in the blood pool noticed for these compounds (81% at 24 h and 65% at 48 h). The tumour-to-background ratio increased with 25% at those longer times. At short times all the tracers were taken up to a considerable extent in the tumours. In the R1M-bearing Wag/Rij rat model only [(123)I]-2-I-L-phenylalanine and [(123)I]-2-I-D-phenylalanine showed an especially high retention at long times without any significant difference between the enantiomers. Copyright 2007 John Wiley & Sons, Ltd.

  8. Crystal growth, spectral, structural and optical studies of π-conjugated stilbazolium crystal: 4-bromobenzaldehyde-4'-N'-methylstilbazolium tosylate.

    PubMed

    Krishna Kumar, M; Sudhahar, S; Bhagavannarayana, G; Mohan Kumar, R

    2014-05-05

    Nonlinear optical (NLO) organic compound, 4-bromobenzaldehyde-4'-N'-methylstilbazolium tosylate was synthesized by reflux method. The formation of molecular complex was confirmed from (1)H NMR, FT-IR and FT-Raman spectral analyses. The single crystals were grown by slow evaporation solution growth method and the crystal structure and atomic packing of grown crystal was identified. The morphology and growth axis of grown crystal were determined. The crystal perfection was analyzed using high resolution X-ray diffraction study on (001) plane. Thermal stability, decomposition stages and melting point of the grown crystal were analyzed. The optical absorption coefficient (α) and energy band gap (E(g)) of the crystal were determined using UV-visible absorption studies. Second harmonic generation efficiency of the grown crystal was examined by Kurtz powder method with different particle size using 1064 nm laser. Laser induced damage threshold study was carried out for the grown crystal using Nd:YAG laser. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Engineering β-oxidation in Yarrowia lipolytica for methyl ketone production.

    PubMed

    Hanko, Erik K R; Denby, Charles M; Sànchez I Nogué, Violeta; Lin, Weiyin; Ramirez, Kelsey J; Singer, Christine A; Beckham, Gregg T; Keasling, Jay D

    2018-05-28

    Medium- and long-chain methyl ketones are fatty acid-derived compounds that can be used as biofuel blending agents, flavors and fragrances. However, their large-scale production from sustainable feedstocks is currently limited due to the lack of robust microbial biocatalysts. The oleaginous yeast Yarrowia lipolytica is a promising biorefinery platform strain for the production of methyl ketones from renewable lignocellulosic biomass due to its natively high flux towards fatty acid biosynthesis. In this study, we report the metabolic engineering of Y. lipolytica to produce long- and very long-chain methyl ketones. Truncation of peroxisomal β-oxidation by chromosomal deletion of pot1 resulted in the biosynthesis of saturated, mono-, and diunsaturated methyl ketones in the C 13 -C 23 range. Additional overexpression and peroxisomal targeting of a heterologous bacterial methyl ketone biosynthesis pathway yielded an initial titer of 151.5 mg/L of saturated methyl ketones. Dissolved oxygen concentrations in the cultures were found to substantially impact cell morphology and methyl ketone biosynthesis. Bioreactor cultivation under optimized conditions resulted in a titer of 314.8 mg/L of total methyl ketones, representing more than a 6000-fold increase over the parental strain. This work highlights the potential of Y. lipolytica to serve as chassis organism for the biosynthesis of acyl-thioester derived long- and very long-chain methyl ketones. Copyright © 2018 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  10. Comparison of different mass spectrometry techniques in the measurement of L-[ring-13C6]phenylalanine incorporation into mixed muscle proteins

    PubMed Central

    Zabielski, Piotr; Ford, G. Charles; Persson, X. Mai; Jaleel, Abdul; Dewey, Jerry D.; Nair, K Sreekumaran

    2013-01-01

    Precise measurement of low enrichment of stable isotope labeled amino-acid tracers in tissue samples is a prerequisite in measuring tissue protein synthesis rates. The challenge of this analysis is augmented when small sample size is a critical factor. Muscle samples from human participants following an 8 hour intravenous infusion of L-[ring-13C6]phenylalanine and a bolus dose of L-[ring-13C6]phenylalanine in a mouse were utilized. Liquid Chromatography tandem mass spectrometry (LC/MS/MS), Gas Chromatography tandem mass spectrometry (GC/MS/MS) and Gas Chromatography/Mass spectrometry (GC/MS) were compared to the Gas Chromatography-Combustion-Isotope Ratio mass spectrometry (GC/C/IRMS), to measure mixed muscle protein enrichment of [ring13C6]phenylalanine enrichment. The sample isotope enrichment ranged from 0.0091 to 0.1312 Molar Percent excess (MPE). As compared with GC/C/IRMS, LC/MS/MS, GC/MS/MS and GC/MS showed coefficients of determination of R2 = 0.9962 and R2 = 0.9942, and 0.9217 respectively. However, the precision of measurements (coefficients of variation) for intra-assay are 13.0%, 1.7%, 6.3% and 13.5% and for inter-assay are 9.2%, 3.2%, 10.2% and 25% for GC/C/IRMS, LC/MS/MS, GC/MS/MS and GC/MS respectively. The muscle sample sizes required to obtain these results were 8μg, 0.8μg, 3μg and 3μg for GC/C/IRMS, LC/MS/MS, GC/MS/MS, and GC/MS respectively. We conclude that LC/MS/MS is optimally suited for precise measurements of L-[ring-13C6]phenylalanine tracer enrichment in low abundance and in small quantity samples. PMID:23378099

  11. Mis-Regulation of 3-Deoxy-d-Arabino-Heptulosonate 7-Phosphate Synthetase Does Not Account for Growth Inhibition by Phenylalanine in Agmenellum quadruplicatum

    PubMed Central

    Jensen, Roy A.; Stenmark-Cox, S.; Ingram, Lonnie O.

    1974-01-01

    The growth of the blue-green bacterium, Agmenellum quadruplicatum, is inhibited in the presence of l-phenylalanine. This species has a single, constitutively synthesized 3-deoxy-d-arabino-heptulosonate 7-phosphate (DAHP) synthetase. l-Phenylalanine inhibits DAHP synthetase non-competitively with respect to both substrate reactants. Other aromatic amino acids do not inhibit the activity of DAHP synthetase. A common expectation for branch-point enzymes such as DAHP synthetase is a balanced pattern of feedback control by all of the ultimate end products. It seemed likely that growth inhibition might equate with defective regulation within the branched aromatic pathway. Accordingly, the possibility was examined that mis-regulation of DAHP synthetase by l-phenylalanine in wild-type cells causes starvation for precursors of the other aromatic end products. However, the molecular basis for growth inhibition cannot be attributed to l-phenylalanine inhibition of DAHP synthetase for the following reasons: (i) DAHP synthetase enzymes from l-phenylalanine-resistant mutants are more, rather than less, sensitive to feedback inhibition by l-phenylalanine. (ii) Shikimate not only fails to antagonize inhibition, but is itself inhibitory. (iii) Neither the sensitivity nor the completeness of l-phenylalanine inhibition of the wild-type enzyme in vitro appears sufficient to account for the potent inhibition of growth in vivo by l-phenylalanine. The dominating effect of l-phenylalanine in the control of DAHP synthetase appears to reflect a mechanism that prevents rather than causes growth inhibition by l-phenylalanine. The alteration of the control of DAHP synthetase in mutants selected for resistance to growth inhibition by l-phenylalanine did indicate that the cause for this metabolite vulnerability can be localized within the aromatic amino acid pathway. Apparently, an aromatic intermediate (between shikimate and the end products) accumulates in the presence of l-phenylalanine

  12. Chloromethyl chlorosulfate as a voltage delay inhibitor in lithium cells

    DOEpatents

    Delnick, F.M.

    1993-04-13

    Chloromethyl chlorosulfate (CMCS) is used as a passive film growth inhibitor in electrochemical cells to minimize voltage delay and low-voltage discharge. Film growth on lithium anodes is significantly diminished when CMCS is added to SOCl[sub 2] and SO[sub 2]Cl[sub 2] electrolytes of lithium batteries. The CMCS also has the effect of extending the shelf-life of Li/SOCl[sub 2] and Li/SO[sub 2]Cl[sub 2] batteries.

  13. Chloromethyl chlorosulfate as a voltage delay inhibitor in lithium cells

    DOEpatents

    Delnick, Frank M.

    1993-01-01

    Chloromethyl chlorosulfate (CMCS) is used as a passive film growth inhibitor in electrochemical cells to minimize voltage delay and low-voltage discharge. Film growth on lithium anodes is significantly diminished when CMCS is added to SOCl.sub.2 and SO.sub.2 Cl.sub.2 electrolytes of lithium batteries. The CMCS also has the effect of extending the shelf-life of Li/SOCl.sub.2 and Li/SO.sub.2 Cl.sub.2 batteries.

  14. Ketones blood test

    MedlinePlus

    Acetone bodies; Ketones - serum; Nitroprusside test; Ketone bodies - serum; Ketones - blood; Ketoacidosis - ketones blood test ... fat cells break down in the blood. This test is used to diagnose ketoacidosis . This is a ...

  15. Inhibition of Fibrillar Assemblies of l-Phenylalanine by Crown Ethers: A Potential Approach toward Phenylketonuria.

    PubMed

    Banik, Debasis; Dutta, Rupam; Banerjee, Pavel; Kundu, Sangita; Sarkar, Nilmoni

    2016-08-11

    In this article, our aim is to investigate the interaction of l-phenylalanine (l-Phe) fibrils with crown ethers (CEs). For this purpose, two different CEs (15-Crown-5 (15C5) and 18-Crown-6 (18C6)) were used. Interestingly, we have observed that both CEs have the ability to arrest fibril formation. However, 18C6 was found to be a better candidate compared to 15C5. Field emission scanning electron microscopy and fluorescence lifetime imaging microscopy were used to monitor the fibril-arresting kinetics of CEs. The arresting process was further confirmed by fluorescence correlation spectroscopy and nuclear magnetic resonance studies.

  16. A comparative study of the vibrational spectra of the anticancer drug melphalan and its fundamental molecules 3-phenylpropionic acid and L-phenylalanine

    NASA Astrophysics Data System (ADS)

    Badawi, Hassan M.; Khan, Ibrahim

    2016-04-01

    The structural stability and the vibrational spectra of the anticancer drug melphalan and its parent compounds 3-phenylpropionic acid and L-phenylalanine were investigated by the DFT B3LYP/6-311G** calculations. Melphalan and its fundamental compounds were predicted to exist predominantly in non-planar structures. The vibrational frequencies of the low energy structures of melphalan, 3-phenylpropionic acid, and phenylalanine were computed at the DFT B3LYP level of theory. Complete vibrational assignments of the normal modes of melphalan, 3-phenylpropionic acid, and phenylalanine were provided by combined theoretical and experimental data of the molecules. The experimental infrared spectra of phenylalanine and melphalan show a significantly different pattern of the Cdbnd O stretching mode as compared to those of normal carboxylic acids. A comparison of the 3700-2000 cm-1 infrared spectral region of the three molecules suggests the presence of similar intermolecular H-bonding in their condensed phases. The observed infrared and Raman spectra are consistent with the presence of one predominant melphalan conformation at room temperature.

  17. Binding of D-phenylalanine and D-tyrosine to carboxypeptidase A.

    PubMed

    Christianson, D W; Mangani, S; Shoham, G; Lipscomb, W N

    1989-08-05

    The structures of the complexes of carboxypeptidase A with the amino acids D-phenylalanine and D-tyrosine are reported as determined by x-ray crystallographic methods to a resolution of 2.0 A. In each individual study one molecule of amino acids binds to the enzyme in the COOH-terminal hydrophobic pocket: the carboxylate of the bound ligand salt links with Arg-145, and the alpha-amino group salt links with Glu-270. The carboxylate of Glu-270 must break its hydrogen bond with the native zinc-bound water molecule in order to exploit the latter interaction. This result is in accord with spectroscopic studies which indicate that the binding of D or L amino acids (or analogues thereof) allows for more facile displacement of the metal-bound water by anions (Bicknell, R., Schaffer, A., Bertini, I., Luchinat, C., Vallee, B. L., and Auld, D. S. (1988) Biochemistry 27, 1050-1057). Additionally, we observe a significant movement of the zinc-bound water molecule (approximately 1 A) upon the binding of D-ligands. We propose that this unanticipated movement also contributes to anion sensitivity. The structural results of the current x-ray study correct predictions made in an early model building study regarding the binding of D-phenylalanine (Lipscomb, W. N., Hartsuck, J. A., Reeke, G. N., Jr., Quiocho, F. A., Bethge, P. H., Ludwig, M. L., Steitz, T. A., Muirhead, H., and Coppola, J. C. (1968) Brookhaven Symp. Biol. 21, 24-90).

  18. L-Phenylalanine functionalized silver nanoparticles: Photocatalytic and nonlinear optical applications

    NASA Astrophysics Data System (ADS)

    Nidya, M.; Umadevi, M.; Sankar, Pranitha; Philip, Reji; Rajkumar, Beulah J. M.

    2015-04-01

    An extensive study on the behavior of L-Phenylalanine capped silver nanoparticles (Phe-Ag NPs) in the aqueous phase and in a sol-gel thin film showed different UV/Vis, Transmission Electron Microscope (TEM), Dynamic Light Scattering and Zeta potential profiles. Scanning Electron Microscope (SEM) images of the samples in the sol gel film showed Ag embedded in the SiO2 matrix. Surface Enhanced Raman Spectra (SERS) confirmed that both in the aqueous media and in the sol gel film, the attachment of Phe to the Ag NP surface was through the benzene ring, with the sol-gel film showing a better enhancement. Photocatalytic degradation of crystal violet was measured spectrophotometrically using Phe-Ag NPs as a nanocatalyst under visible light illumination. Intensity-dependent nonlinear optical absorption of Phe-Ag measured using the open aperture Z-scan technique revealed that the material is an efficient optical limiter with potential applications.

  19. Phenylalanine ammonia-lyase. Induction and purification from yeast and clearance in mammals.

    PubMed

    Fritz, R R; Hodgins, D S; Abell, C W

    1976-08-10

    Yeast phenylalanine ammonia-lyase (EC 4.3.1.5) catalyzes the deamination of L-phenylalanine to form trans-cinnamic acid and tyrosine to trans-coumaric acid. Maximal enzyme activity in Rhodotorula glutinis (2 units/g, wet weight, of yeast) was induced in late-log phase (12 to 14 hours) of growth in a culture medium containing 1.0% malt extract, 0.1% yeast extract, and 0.1% L-phenylalanine. A highly purified enzyme was obtained by fractionation with ammonium sulfate and sodium citrate followed by chromatography on DEAE-cellulose and Sephadex G-200. The active preparation yielded a major component on three different polyacrylamide gel electrophoretic systems. Antisera to phenylalanine ammonia-lyase was raised in rabbits and detected by double immunodiffusion. The antigen-antibody complex was enzymatically active in vitro. The biological half-life of the enzyme was approximately 21 hours in several mammalian species (mice without and with BW10232 adenocarcinoma and B16 melanoma, rats, and monkeys) after a single injection; however, upon repeated administration, phenylalanine ammonia-lyase had a much shorter biological half-life. The onset of rapid clearance occurred earlier in tumor-bearing than in nontumor-bearing mice indicating a direct or indirect influence by the tumor on the biological half-life of phenylalanine ammonia-lyase.

  20. n-BuLi as a highly efficient precatalyst for hydrophosphonylation of aldehydes and unactivated ketones.

    PubMed

    Liu, Chengwei; Zhang, Yu; Qian, Qinqin; Yuan, Dan; Yao, Yingming

    2014-12-05

    It was found for the first time that organic alkali metal compounds serve as highly efficient precatalysts for the hydrophosphonylation reactions of aldehydes and unactivated ketones with dialkyl phosphite under mild conditions. For ketone substrates, a reversible reaction was observed, and the influence of catalyst loading and reaction temperature on the reaction equilibrium was studied in detail. Overall, the hydrophosphonylation reactions catalyzed by 0.1 mol % n-BuLi were completed within 5 min for a broad range of substrates and generated a series of α-hydroxy phosphonates in high yields.

  1. Enantioselective Reduction of Ketones Catalyzed by Rare-Earth Metals Complexed with Phenoxy Modified Chiral Prolinols.

    PubMed

    Song, Peng; Lu, Chengrong; Fei, Zenghui; Zhao, Bei; Yao, Yingming

    2018-06-01

    Enantioselective reduction of ketones and α,β-unsaturated ketones by pinacolborane (HBpin) has been well-established by using chiral rare-earth metal catalysts with phenoxy modified prolinols. A number of highly optically active alcohols were obtained from reduction of simple ketones catalyzed by ytterbium complex 1 [L 4 Yb(L 4 H)] (H 2 L 4 = ( S)-2- tert-butyl-6-((2-(hydroxydiphenylmethyl)pyrrolidin-1-yl)methyl)phenol). Moreover, α,β-unsaturated ketones were selectively reduced to a wide range of chiral allylic alcohols with excellent yields, high enantioselectivity, and complete chemoselectivity, catalyzed by a single component chiral ytterbium complex 2 [L 1 Yb(L 1 H)] (H 2 L 1 = ( S)-2,4-di- tert-butyl-6-((2-(hydroxydiphenylmethyl)pyrrolidin-1-yl)methyl)phenol).

  2. Synthesis of Novel Chiral Sulfonamide-Bearing 1,2,4-Triazole-3-thione Analogs Derived from D- and L-Phenylalanine Esters as Potential Anti-Influenza Agents.

    PubMed

    Başaran, Eyüp; Karaküçük-Iyidoğan, Ayşegül; Schols, Dominique; Oruç-Emre, Emine Elçin

    2016-06-01

    Novel enantiopure 1,2,4-trizole-3-thiones containing a benzensulfonamide moiety were synthesized via multistep reaction sequence starting with D-phenylalanine methyl ester and L-phenylalanine ethyl ester as a source of chirality. The chemical structures of all compounds were characterized by elemental analysis, UV, IR, (1) H NMR, (13) C NMR, 2D NMR (HETCOR), and mass spectral data. All compounds were tested in vitro antiviral activity against a broad variety of DNA and RNA viruses and in vitro cytostatic activity against murine leukemia (L1210), human T-lymphocyte (CEM) and human cervix carcinoma (HeLa) cell lines. Although enantiopure 1,2,4-triazole-3-thione analogs in (R) configuration emerged as promising anti-influenza A H1N1 subtype in Madin Darby canine kidney cell cultures (MDCK), their enantiomers exhibited no activity. Especially compounds , , , , and (EC50 : 6.5, 6.1, 2.4, 1.6, 1.7 μM, respectively) had excellent activity against influenza A H1N1 subtype compared to the reference drug ribavirin (EC50 : 8.0 μM). Several compounds have been found to inhibit proliferation of L1210, CEM and HeLa cell cultures with IC50 in the 12-53 μM range. Compound and in (R) configuration were the most active compounds (IC50 : 12-22 μM for and IC50 : 19-23 μM for ). Chirality 28:495-513, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  3. The acetylation of insulin

    PubMed Central

    Lindsay, D. G.; Shall, S.

    1971-01-01

    The acetylation of the free amino groups of insulin was studied by reaction of the hormone with N-hydroxysuccinimide acetate at pH6.9 and 8.5. The products formed were separated by chromatography on DEAE-Sephadex and were characterized by isoelectric focusing, by end-group analysis, by the incorporation of [3H]acetyl groups in the molecule, and by treatment with trypsin that had been treated with 1-chloro-4-phenyl-3-toluene-p-sulphonamidobutan-2-one (`tosylphenylalanyl chloromethyl ketone'). Three monosubstituted products, two disubstituted products and one trisubstituted derivative were prepared. The α-amino groups of the terminal residues and the ∈-amino group of the lysine-B29 were the sites of reaction. Acetylation of any of the free amino groups did not affect the biological activity of insulin. It was demonstrated, however, that substitution at the glycine-A1 amino group by the larger residues, acetoacetyl or thiazolidinecarbonyl, produced a decrease in biological activity. Modification of the lysine-B29 or phenylalanine-B1 amino groups with these larger reagents did not affect the biological activity. Modification of the phenylalanine-B1 amino group by any of the three substituents resulted in a large decrease in the affinity of insulin for anti-insulin antibodies raised in the guinea pig. Modification of the other two amino groups did not affect the reaction with antibody. These observations are correlated with the tertiary structure of insulin. ImagesFig. 4. PMID:5113488

  4. Clearance of phenylalanine ammonia-lyase from normal and tumor-bearing mice.

    PubMed

    Shen, R S; Fritz, R R; Abell, C W

    1977-04-01

    Yeast phenylalanine ammonia-lyase was administered i.p. to normal and tumor-bearing mice, and its clearance from plasma was studied. Single and multiple weekly injections at dosages of 10,20,50 and 100 units/kg were administered to C57BL female, C57BL X DBA/2F1 male, and A/J female mice. L5178Y murine lymphoblastic leukemia, B16 melanoma, BW10232 adenocarcinoma, and 15091A anaplastic carcinoma were implanted 7 to 11 days prior to enzyme injection in the appropriate host. After a single injection, the average plasma half-lives of phenylalanine ammonia-lyase were 18 to 24 hr in all groups studied. While the other tumors had no effect on the plasma level of phenylalanine ammonia-lyase after a single injection, L5178Y murine lymphoblastic leukemia and 15091A anaplastic carcinoma significantly depressed the maximal level of phenylalanine ammonia-lyase attained in the plasma. After repeated injections of phenylalanine ammonia-lyase, the initial plasma enzyme level was significantly reduced when 20 units/kg were administered, and the clearance of the enzyme from the plasma was greatly accelerated regardless of the amount administered. Furthermore, in tumor-bearing mice, the rate of clearance was significantly more rapid than in the appropriate non-tumor-bearing control.

  5. Synthesis of the insecticide prothrin and its analogues from biomass-derived 5-(Chloromethyl) furfural

    USDA-ARS?s Scientific Manuscript database

    Prothrin, a synthetic pyrethroid insecticide, was synthesized from the biomass-derived platform chemical 5 (chloromethyl)furfural in six steps and overall 65% yield. Two structural analogues of prothrin were also prepared following the same synthetic approach. Preliminary testing of these furan-base...

  6. Titania-catalyzed radiofluorination of tosylated precursors in highly aqueous medium

    DOE PAGES

    Sergeev, Maxim E.; Morgia, Federica; Lazari, Mark; ...

    2015-04-10

    Nucleophilic radiofluorination is an efficient synthetic route to many positron-emission tomography (PET) probes, but removal of water to activate the cyclotron-produced [ 18F]fluoride has to be performed prior to reaction, which significantly increases overall radiolabeling time and causes radioactivity loss. In this paper, we demonstrate the possibility of 18F-radiofluorination in highly aqueous medium. The method utilizes titania nanoparticles, 1:1 (v/v) acetonitrile–thexyl alcohol solvent mixture, and tetra-n-butylammonium bicarbonate as a phase-transfer agent. Efficient radiolabeling is directly performed with aqueous [ 18F]fluoride without the need for a drying/azeotroping step to significantly reduce radiosynthesis time. High radiochemical purity of the target compound ismore » also achieved. Finally, the substrate scope of the synthetic strategy is demonstrated with a range of aromatic, aliphatic, and cycloaliphatic tosylated precursors.« less

  7. The study of structure-activity relationships among substituted N-benzoyl derivatives of phenylalanine and its analogs in a microbial antitumor prescreen: II. Derivatives of m-fluoro-DL-phenylalanine.

    PubMed

    Otani, T T; Briley, M R

    1983-05-01

    The fluoro-, chloro-, methoxy- and nitro-substituted benzoyl derivatives of m-fluoro-DL-phenylalanine, substituted singly at the ortho, meta or para position of the benzoyl phenyl ring, were prepared and tested for growth-inhibitory activity in a Lactobacillus casei system used as an antitumor prescreen. The substituted benzoyl derivatives that were previously found to be the most active for o-fluoro-DL-phenylalanine were also the most active for the m-fluoro-DL-phenylalanine. The position of the fluorine substituent in the phenylalanine also appeared to be important for inhibitory activity as the derivatives of m-fluoro-phenylalanine were in general better inhibitors than those of the corresponding o-fluorophenylalanine.

  8. The adsorption of L-phenylalanine on oxidized single-walled carbon nanotubes.

    PubMed

    Piao, Lingyu; Liu, Quanrun; Li, Yongdan; Wang, Chen

    2009-02-01

    A simple and green approach was proceeded to obtain a stable single-walled carbon nanotubes (SWNTs)/L-phenylalanine (Phe) solution. The oxidized SWNTs (OSWNT) were used in this work. The scanning electron microscopy (SEM), High-resolution transmission electron microscopy (HRTEM), Raman spectrometer, Fourier transform-infrared resonance (FT-IR), Ultraviolet-visible (UV-vis) spectroscopy, Thermogravimetric analysis (TGA) and High performance liquid chromatography (HPLC) were joined together to investigate the interaction between OSWNT and Phe. The OSWNT became soluble in the water and formed a stable solution since the Phe was adsorbed. The absorbed amount of Phe on the OSWNT is around 33 wt%. Adsorption of the Phe was mainly carried out on the OSWNT with smaller diameters. The Phe molecules were absorbed on the OSWNT by conjunct interaction of the pi-pi stacking, hydrogen bond and part of covalent bond.

  9. Serum phenylalanine screening

    MedlinePlus

    ... phenylalanine. If PKU is not detected early, increasing phenylalanine levels in the baby will cause intellectual disability. When discovered early, changes in the diet can help prevent the severe side effects of PKU.

  10. Diffusion coefficients in systems with inclusion compounds. 1. alpha. -Cyclodextrin-L-phenylalanine-water at 25 degree C

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Paduano, L.; Sartorio, R.; Vitagliano, V.

    Diffusion coefficients in the ternary system {alpha}-cyclodextrin (at one concentration)-L-phenylalanine (at four concentrations)-water have been measured by using the Gouy interferometric technique. The effect of the inclusion equilibrium on the cross-term diffusion coefficients was observed. The measured diffusion coefficients in the ternary systems were used to calculate values of the binding constants. These values are in good agreement with the value obtained from calorimetric studies.

  11. The effects of ionizing radiations on L-, DL-phenylalanine and L-, DL- tryptophase studied by ultra-violet and infra-red spectrophotometry

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Korgaonkar, K S; Donde, R B

    Aqueous solutions of L-, DL-phenylalanlne and L-, DLtryptophane were irradiated with Co 60 gamma rays. Marked changes in the ultraviolet spectra of the samples and in the infra-red spectra of their solid residues were noted. The radiosensitivities of these irradiated molecules in terms of G-values were determined, and the modes of action and the nature of irradiation products are discussed. A common order of radiosensitivities among the three aromatic amino acids both L-, and DL-forms is observed. Apparent differences In the ultraviolet spectral responses of tryptophane on the one hand and phenylalanine and tyrosine on the other are explained. Evidencemore » is presented suggesting some common radiation end-product of a cellulose or sugar type from these aromatic amino acids.« less

  12. Enhancement of L-3-hydroxybutyryl-CoA dehydrogenase activity and circulating ketone body levels by pantethine. Relevance to dopaminergic injury.

    PubMed

    Cornille, Emilie; Abou-Hamdan, Mhamad; Khrestchatisky, Michel; Nieoullon, André; de Reggi, Max; Gharib, Bouchra

    2010-04-23

    The administration of the ketone bodies hydroxybutyrate and acetoacetate is known to exert a protective effect against metabolic disorders associated with cerebral pathologies. This suggests that the enhancement of their endogenous production might be a rational therapeutic approach. Ketone bodies are generated by fatty acid beta-oxidation, a process involving a mitochondrial oxido-reductase superfamily, with fatty acid-CoA thioesters as substrates. In this report, emphasis is on the penultimate step of the process, i.e. L-3-hydroxybutyryl-CoA dehydrogenase activity. We determined changes in enzyme activity and in circulating ketone body levels in the MPTP mouse model of Parkinson's disease. Since the active moiety of CoA is pantetheine, mice were treated with pantethine, its naturally-occurring form. Pantethine has the advantage of being known as an anti-inflammatory and hypolipidemic agent with very few side effects. We found that dehydrogenase activity and circulating ketone body levels were drastically reduced by the neurotoxin MPTP, whereas treatment with pantethine overcame these adverse effects. Pantethine prevented dopaminergic neuron loss and motility disorders. In vivo and in vitro experiments showed that the protection was associated with enhancement of glutathione (GSH) production as well as restoration of respiratory chain complex I activity and mitochondrial ATP levels. Remarkably, pantethine treatment boosted the circulating ketone body levels in MPTP-intoxicated mice, but not in normal animals. These finding demonstrate the feasibility of the enhancement of endogenous ketone body production and provide a promising therapeutic approach to Parkinson's disease as well as, conceivably, to other neurodegenerative disorders.

  13. Value of point-of-care ketones in assessing dehydration and acidosis in children with gastroenteritis.

    PubMed

    Levy, Jason A; Waltzman, Mark; Monuteaux, Michael C; Bachur, Richard G

    2013-11-01

    Children with gastroenteritis often develop dehydration with metabolic acidosis. Serum ketones are frequently elevated in this population. The goal was to determine the relationship between initial serum ketone concentration and both the degree of dehydration and the magnitude of acidosis. This was a secondary analysis of a prospective trial of crystalloid administration for rapid rehydration. Children 6 months to 6 years of age with gastroenteritis and dehydration were enrolled. A point-of-care serum ketone (beta-hydroxybutyrate) concentration was obtained at the time of study enrollment. The relationship between initial serum ketone concentration and a prospectively assigned and previously validated clinical dehydration score, and serum bicarbonate concentration, was analyzed. A total of 188 patients were enrolled. The median serum ketone concentration was elevated at 3.1 mmol/L (interquartile range [IQR] = 1.2 to 4.6 mmol/L), and the median dehydration score was consistent with moderate dehydration. A significant positive relationship was found between serum ketone concentration and the clinical dehydration score (Spearman's rho = 0.22, p = 0.003). Patients with moderate dehydration had a higher median serum ketone concentration than those with mild dehydration (3.6 mmol/L vs. 1.4 mmol/L, p = 0.007). Additionally, the serum ketone concentration was inversely correlated with serum bicarbonate concentration (ρ = -0.26, p < 0.001). Children with gastroenteritis and dehydration have elevated serum ketone concentrations that correlate with both degree of dehydration and magnitude of metabolic acidosis. Point-of-care serum ketone measurement may be a useful tool to inform management decisions at the point of triage or in the initial evaluation of children with gastroenteritis and dehydration. © 2013 by the Society for Academic Emergency Medicine.

  14. Crystal Structure of LAAO from Calloselasma rhodostoma with L-Phenylalanine Substrate: Insights into Structure and Mechanism

    PubMed Central

    Moustafa, Ibrahim M.; Foster, Scott; Lyubimov, Artem Y.; Vrielink, Alice

    2007-01-01

    L-amino acid oxidase (LAAO) is a dimeric glycosylated flavoenzyme, a major constituent of the snake-venom from Calloselasma rhodostoma. The enzyme exhibits apoptosis-inducing effects as well as antibacterial and anti-HIV activities. The structure of LAAO with its substrate (L-phenylalanine) has been refined to a resolution of 1.8 Å. The complex structure reveals the substrate bound to the reduced flavin (FADred). Alternate conformations for the key residues: His223 and Arg322 are evident, suggesting a dynamic active site. Furthermore conformational changes are also apparent for the isoalloxazine ring; the three ring system exhibits more bending around the N5—N10 axis compared to the oxidized flavin. The implications of the observed dynamics on the mechanism of catalysis are discussed. Inspection of buried surfaces in the enzyme reveals a Y shaped channel system extending from the external surface of the protein to the active site. One portion of this channel may serve as the entry path for O2 during the oxidative half reaction. The second region, separated from the proposed O2 channel by the N-terminus (residues 8 – 16) of the protein, may play a role in H2O2 release. Interestingly, the later portion of the channel would direct the H2O2 product to the exterior surface of the protein, near to the glycan moiety, thought to anchor the enzyme to the host cell. This channel location may explain the ability of the enzyme to localize H2O2 to the targeted cell inducing the apoptotic effect. PMID:17046020

  15. Thermal, optical, mechanical and electrical properties of a novel NLO active L-phenylalanine L-phenylalaninium perchlorate single crystals

    NASA Astrophysics Data System (ADS)

    Cyrac Peter, A.; Vimalan, M.; Sagayaraj, P.; Madhavan, J.

    2010-01-01

    Single crystals of L-phenylalanine L-phenylalaninium perchlorate (LPAPCl), a semiorganic nonlinear (NLO) material have been successfully grown up to a size of 14 mm×5 mm×3 mm. The lattice parameters of the grown crystals are determined by single crystal XRD. The UV-Vis-NIR spectrum of LPAPCl show less optical absorption in the entire visible region. Nonlinear optical study reveals that the SHG efficiency of LPAPCl is nearly 1.4 times that of KDP. The laser damage density is found to be 7.4 GW/cm 2. The crystals are subjected to microhardness studies and the variation of the microhardness with the applied load is studied. The response of dielectric constant in the frequency region of 50 Hz to 5 MHz has been investigated. AC and DC conductivity and photoconductivity experiments are also carried out and the results are discussed.

  16. N-heterocyclic carbene catalysed asymmetric cross-benzoin reactions of heteroaromatic aldehydes with trifluoromethyl ketones.

    PubMed

    Enders, Dieter; Grossmann, André; Fronert, Jeanne; Raabe, Gerhard

    2010-09-14

    A new triazolium salt derived N-heterocyclic carbene catalyses an asymmetric cross-benzoin-type reaction of heteroaromatic aldehydes and various trifluoromethyl ketones in good to excellent yields (69-96%) and moderate to good enantioselectivities (ee = 39-85%). Up to 99% ee can be achieved by recrystallisation.

  17. Enhanced biosynthesis of chiral phenyllactic acid from L-phenylalanine through a new whole-cell biocatalyst.

    PubMed

    Zheng, Zhaojuan; Xia, Meijuan; Fang, Xuchao; Jiang, Ting; Ouyang, Jia

    2018-06-22

    Phenyllactic acid (PLA) is a high-value compound, which was usually produced by lactic acid bacteria (LAB) as biocatalysts and glucose or phenylpyruvic acid (PPA) as starting materials for PLA synthesis in previous studies. However, the PLA produced using LAB is a racemic mixture. Besides, both glucose and PPA were unsatisfactory substrates, as the former could not produce high concentrations of PLA while the latter is not a renewable and green substrate. To overcome these drawbacks, in this study, a new biotransformation process was developed for chiral PLA production from L-phenylalanine via the intermediate PPA using recombinant Escherichia coli co-expressing L-amino acid deaminase, NAD-dependent L-lactate dehydrogenase or NAD-dependent D-lactate dehydrogenase, and formate dehydrogenase. After optimization, the recombinant E. coli produced L- and D-PLA at concentrations of 59.9 and 60.3 mM in 6 h, respectively. Hence, this process provides an effective and promising alternative method for chiral PLA production.

  18. Antinociceptive effect of some carboxypeptidase A inhibitors in comparison with D-phenylalanine.

    PubMed

    Giusti, P; Carrara, M; Cima, L; Borin, G

    1985-10-22

    It had previously been shown that D-phenylalanine and hydrocinnamic acid, two in vitro inhibitors of carboxypeptidase A, possess an analgesic action when injected i.p. in mice. We have studied the in vivo effects of indole-3-acetic acid, another carboxypeptidase A inhibitor, and of the following analogs of D-phenylalanine substituted in position 4: D-tyrosine, p-fluoro-D-phenylalanine and trifluoroacetyl-p-fluoro-D-phenylalanine. Whereas indole-3-acetic acid caused a higher and shorter analgesia in comparison with D-phenylalanine, p-fluoro-D-phenylalanine and its N-trifluoroacetyl derivative yielded both a greater and a much longer lasting analgesic effect. Since the latter compound showed only slight inhibitory activity on carboxypeptidase A in vitro, we suggest that inhibition of this enzyme and analgesia might not be directly correlated.

  19. Precise structural analysis of α-helical polypeptide by quantum-chemical calculation related to reciprocal side-chain combination of two L-phenylalanine residues

    NASA Astrophysics Data System (ADS)

    Niimura, Subaru; Kurosu, Hiromichi; Shoji, Akira

    2010-04-01

    To clarify the positive role of side-chain conformation in the stability of protein secondary structure (main-chain conformation), we successfully calculated the optimization structure of a series of well-defined α-helical octadecapeptides composed of two L-phenylalanine (Phe) and 16 L-alanine (Ala) residues, based on the molecular orbital calculation with density functional theory (DFT/B3LYP/6-31G(d)). From the total energy calculation and the precise secondary structural analysis, we found that the conformational stability of the α-helix is closely related to the reciprocal side-chain combinations (such as positional relation and side-chain conformation) of two Phe residues in this system. Furthermore, we demonstrated that the 1H, 13C, 15N and 17O isotropic chemical shifts of each Phe residue depend on the respective side-chain conformations of the Phe residue.

  20. Spectroscopic analyses on interaction of o-Vanillin- D-Phenylalanine, o-Vanillin- L-Tyrosine and o-Vanillin- L-Levodopa Schiff Bases with bovine serum albumin (BSA)

    NASA Astrophysics Data System (ADS)

    Gao, Jingqun; Guo, Yuwei; Wang, Jun; Wang, Zhiqiu; Jin, Xudong; Cheng, Chunping; Li, Ying; Li, Kai

    2011-04-01

    In this work, three o-Vanillin Schiff Bases (o-VSB: o-Vanillin- D-Phenylalanine (o-VDP), o-Vanillin- L-Tyrosine (o-VLT) and o-Vanillin- L-Levodopa (o-VLL)) with alanine constituent were synthesized by direct reflux method in ethanol solution, and then were used to study the interaction to bovine serum albumin (BSA) molecules by fluorescence spectroscopy. Based on the fluorescence quenching calculation, the bimolecular quenching constant ( Kq), apparent quenching constant ( Ksv), effective binding constant ( KA) and corresponding dissociation constant ( KD) as well as binding site number ( n) were obtained. In addition, the binding distance ( r) was also calculated according to Foster's non-radioactive energy transfer theory. The results show that these three o-VSB can efficiently bind to BSA molecules, but the binding array order is o-VDP-BSA > o-VLT-BSA > o-VLL-BSA. Synchronous fluorescence spectroscopy indicates that the o-VDP is more accessibility to tryptophan (Trp) residues of BSA molecules than to tyrosine (Tyr) residues. Nevertheless, the o-VLT and o-VLL are more accessibility to Tyr residues than to Trp residues.

  1. Effects of L-histidine depletion and L-tyrosine/L-phenylalanine depletion on sensory and motor processes in healthy volunteers

    PubMed Central

    van Ruitenbeek, P; Sambeth, A; Vermeeren, A; Young, SN; Riedel, WJ

    2009-01-01

    Background and purpose: Animal studies show that histamine plays a role in cognitive functioning and that histamine H3-receptor antagonists, which increase histaminergic function through presynaptic receptors, improve cognitive performance in models of clinical cognitive deficits. In order to test such new drugs in humans, a model for cognitive impairments induced by low histaminergic functions would be useful. Studies with histamine H1-receptor antagonists have shown limitations as a model. Here we evaluated whether depletion of L-histidine, the precursor of histamine, was effective in altering measures associated with histamine in humans and the behavioural and electrophysiological (event-related-potentials) effects. Experimental approach: Seventeen healthy volunteers completed a three-way, double-blind, crossover study with L-histidine depletion, L-tyrosine/L-phenylalanine depletion (active control) and placebo as treatments. Interactions with task manipulations in a choice reaction time task were studied. Task demands were increased using visual stimulus degradation and increased response complexity. In addition, subjective and objective measures of sedation and critical tracking task performance were assessed. Key results: Measures of sedation and critical tracking task performance were not affected by treatment. L-histidine depletion was effective and enlarged the effect of response complexity as measured with the response-locked lateralized readiness potential onset latency. Conclusions and implications: L-histidine depletion affected response- but not stimulus-related processes, in contrast to the effects of H1-receptor antagonists which were previously found to affect primarily stimulus-related processes. L-histidine depletion is promising as a model for histamine-based cognitive impairment. However, these effects need to be confirmed by further studies. PMID:19413574

  2. Ambient Temperature Synthesis of High Enantiopurity N-Protected Peptidyl Ketones by Peptidyl Thiol Ester–Boronic Acid Cross-Coupling

    PubMed Central

    Yang, Hao; Li, Hao; Wittenberg, Rüdiger; Egi, Masahiro; Huang, Wenwei; Liebeskind, Lanny S.

    2009-01-01

    α-Amino acid thiol esters derived from N-protected mono-, di-, and tripeptides couple with aryl, π-electron-rich heteroaryl, or alkenyl boronic acids in the presence of stoichiometric Cu(I) thiophene-2-carboxylate (CuTC) and catalytic Pd2(dba)3/triethylphosphite to generate the corresponding N-protected peptidyl ketones in good to excellent yields and in high enantiopurity. Triethylphosphite plays a key role as a supporting ligand by mitigating an undesired palladium-catalyzed decarbonylation-β-elimination of the α-amino thiol esters. The peptidyl ketone synthesis proceeds at room temperature under non-basic conditions and demonstrates a high tolerance to functionality. PMID:17263394

  3. Direct asymmetric aldol reactions between aldehydes and ketones catalyzed by L-tryptophan in the presence of water.

    PubMed

    Jiang, Zhaoqin; Yang, Hui; Han, Xiao; Luo, Jie; Wong, Ming Wah; Lu, Yixin

    2010-03-21

    Primary amino acids and their derivatives were investigated as catalysts for the direct asymmetric aldol reactions between ketones and aldehydes in the presence of water, and L-tryptophan was shown to be the best catalyst. Solvent effects, substrate scope and the influence of water on the reactions were investigated. Quantum chemical calculations were performed to understand the origin of the observed stereoselectivity.

  4. Racemization of aspartic acid and phenylalanine in the sweetener aspartame at 100 degrees C.

    PubMed Central

    Boehm, M F; Bada, J L

    1984-01-01

    The racemization half-lives (i.e., the time required to reach a D/L = 0.33) at pH 6.8 for aspartic acid and phenylalanine in the sweetener aspartame (L-aspartyl-L-phenylalanine methyl ester) were determined to be 13 and 23 hours, respectively, at 100 degrees C. Racemization at this pH does not occur in aspartame but rather in its diketopiperazine decomposition product. Our results indicate that the use of aspartame to sweeten neutral pH foods and beverages that are then heated at elevated temperature could generate D-aspartic acid and D-phenylalanine. The nutritive consequences of these D-amino acids in the human diet are not well established, and thus aspartame should probably not be used as a sweetener when the exposure of neutral pH foods and beverages to elevated temperatures is required. At pH 4, a typical pH of most foods and beverages that might be sweetened with aspartame, the half-lives are 47 hours for aspartic acid and 1200 hours for phenylalanine at 100 degrees C. Racemization at pH 4 takes place in aspartame itself. Although the racemization rates at pH 4 are slow and no appreciable racemization of aspartic acid and phenylalanine should occur during the normal use of aspartame, some food and beverage components could conceivably act as catalysts. Additional studies are required to evaluate whether the use of aspartame as a sugar substitute might not in turn result in an increased human consumption of D-aspartic acid and D-phenylalanine. PMID:6591191

  5. Pentynyl dextran as a support matrix for immobilization of serine protease subtilisin Carlsberg and its use for transesterification of N-acetyl-L-phenylalanine ethyl ester in organic media.

    PubMed

    Tahir, Muhammad Nazir; Cho, Eunae; Mischnick, Petra; Lee, Jae Yung; Yu, Jae-Hyuk; Jung, Seunho

    2014-04-01

    In this study, serine protease (subtilisin Carlsberg) was immobilized on pentynyl dextran (PyD, O-alkynyl ether of dextran, 1) and used for the transesterification of N-acetyl-L-phenylalanine ethyl ester (2) with different aliphatic (1-propanol, 1-butanol, 1-pentanol, 1-hexanol) and aromatic (benzyl alcohol, 2-phenyl ethanol, 4-phenyl-1-butanol) alcohols in tetrahydrofuran (THF). The effect of carbon chain length in aliphatic and aromatic alcohols on initial and average transesterification rate, transesterification activity of immobilized enzyme and yield of the reaction under selected reaction conditions was investigated. The transesterification reactivity of the enzyme and yield of the reaction increased as the chain length of the alcohols decreased. Furthermore, almost no change in yield was observed when the immobilized enzyme was repeatedly used for selected alcohols over six cycles. Intrinsic fluorescence analysis showed that the catalytic activity of the immobilized enzyme in THF was maintained due to retention of the tertiary structure of the enzyme after immobilization on PyD (1).

  6. Efficacy of 3,5-dibromo-L-phenylalanine in rat models of stroke, seizures and sensorimotor gating deficit.

    PubMed

    Cao, W; Shah, H P; Glushakov, A V; Mecca, A P; Shi, P; Sumners, C; Seubert, C N; Martynyuk, A E

    2009-12-01

    Abnormal glutamatergic activity is implicated in neurologic and neuropsychiatric disorders. Selective glutamate receptor antagonists were highly effective in animal models of stroke and seizures but failed in further clinical development because of serious side effects, including an almost complete set of symptoms of schizophrenia. Therefore, the novel polyvalent glutamatergic agent 3,5-dibromo-L-phenylalanine (3,5-DBr-L-Phe) was studied in rat models of stroke, seizures and sensorimotor gating deficit. 3,5-DBr-L-Phe was administered intraperitoneally as three boluses after intracerebral injection of endothelin-1 (ET-1) adjacent to the middle cerebral artery to cause brain injury (a model of stroke). 3,5-DBr-L-Phe was also given as a single bolus prior to pentylenetetrazole (PTZ) injection to induce seizures or prior to the administration of the N-methyl-D-aspartate (NMDA) receptor antagonist dizocilpine (MK-801) to cause disruption of prepulse inhibition (PPI) of startle (sensorimotor gating deficit). Brain damage caused by ET-1 was reduced by 52%, which is comparable with the effects of MK-801 in this model as reported by others. 3,5-DBr-L-Phe significantly reduced seizures induced by PTZ without the significant effects on arterial blood pressure and heart rate normally caused by NMDA antagonists. 3,5-DBr-L-Phe prevented the disruption of PPI measured 3 days after the administration of ET-1. 3,5-DBr-L-Phe also eliminated sensorimotor gating deficit caused by MK-801. The pharmacological profile of 3,5-DBr-L-Phe might be beneficial not only for developing a therapy for the neurological and cognitive symptoms of stroke and seizures but also for some neuropsychiatric disorders.

  7. Molecular events involved in the increased expression of matrix metalloproteinase-9 by T lymphocytes of mammary tumor-bearing mice.

    PubMed

    Owen, Jennifer L; Torroella-Kouri, Marta; Iragavarapu-Charyulu, Vijaya

    2008-01-01

    Matrix metalloproteinases (MMPs) are a family of extracellular proteinases whose contributions to cancer progression have been studied because of their matrix-degrading abilities and elevated expression in advanced stage tumors. Recent findings suggest a role for MMPs during the multiple stages of tumor progression including establishment and growth, migration, invasion, metastasis, and angiogenesis. MMP-9 regulation at the molecular level can be studied by measuring the effect(s) of a variety of physiological and pharmacological agents on cells. Multiple signaling molecules such as protein kinase C, pertussis toxin-sensitive guanine nucleotide-binding protein G, and protein tyrosine kinases are known to mediate the secretion of MMPs in cell lines. We previously reported an upregulation of MMP-9 in T cells of mammary tumor-bearing mice. In this study, pharmacologic inhibitors were used to dissect the signaling pathways involved in the upregulation of MMP-9 in the splenic T cells of normal and mammary tumor-bearing mice. Staurosporine, a protein kinase inhibitor, stimulated MMP-9 secretion by normal T lymphocytes, while the constitutively high levels of MMP-9 produced by tumor bearers' T cells were decreased by Genistein, a specific tyrosine kinase inhibitor, and Rottlerin, a PKC inhibitor. Using a NF-kappaB specific probe to the murine MMP-9 promoter, electromobility shift assays of nuclear proteins from normal and tumor bearers' splenic T cells revealed a pattern of higher intensity bands from the tumor bearers' nuclear extracts, indicating a greater amount of these transcription factors bound to the recognition motif. When mammary tumor bearers' T cells were cultured with the NF-kappaB inhibitors, N-p-Tosyl-L-lysine chloromethyl ketone hydrochloride and Bay 11-7082, there was a subsequent decreased production of MMP-9. These results suggest that the tumor burden may be activating various signaling pathways within splenic T lymphocytes to upregulate MMP-9

  8. Effect of N-benzoyl-D-phenylalanine, a new potential oral antidiabetic agent, in neonatal streptozotocin-induced diabetes in rats.

    PubMed

    Pari, Leelavinothan; Ashokkumar, Natarajan

    2005-01-01

    The present investigation was undertaken to study the effect of treatment with D-phenylalanine derivative and metformin in neonatal streptozotocin (nSTZ)-induced non-insulin-dependent diabetes mellitus (NIDDM) in rats. To induce NIDDM, a single dose injection of streptozotozin (STZ) (100 mg kg(-1); ip) was given to 2-day-old rats. After 10-12 weeks, rats weighing above 150 g were selected for screening in NIDDM model. They were checked for fasting blood glucose levels to conform the status of NIDDM. D-phenylalanine derivative (50, 100 and 200 mg kg(-1)) was administered per os (po) for 6 weeks to the rats with confirmed diabetes. A group of diabetic rats was also maintained and this group received metformin as comparative drug. Significant decrease in blood glucose with significant increase in plasma insulin was observed in group receiving 100 mg of D-phenylalanine derivative plus 500 mg of metformin.

  9. Studies on the in vitro and in vivo hydrolysis and intramolecular aminolysis of L-aspartyl-l-phenylalanine methyl ester

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bouvette, R.E.

    The disposition and metabolism of L-aspartyl-L-(/sup 14/C-phenyl) alanine methyl ester (/sup 14/C-APM) was studied in male Sprague-Dawley rats after a single intragastric injection. Plasma levels of /sup 14/C-activity increased slowly within the first four hours after a 5 ..mu..Ci dose. Within 2 hours after injection 90% of the /sup 14/C-activity observed in the plasma was incorporated into precipitated proteins. HPLC analysis of the deproteinated plasma showed the /sup 14/C-activity present to be in the form of phenylalanine Disposition studies of /sup 14/C-APM 4 hours after a single intragastric dose showed the highest organs of /sup 14/C-accumulation to be the blood,more » liver, stomach, and small intestine. The molecular form of the /sup 14/C-activity in the tissues was not determined.« less

  10. Expression and Properties of the Highly Alkalophilic Phenylalanine Ammonia-Lyase of Thermophilic Rubrobacter xylanophilus

    PubMed Central

    Kovács, Klaudia; Bánóczi, Gergely; Varga, Andrea; Szabó, Izabella; Holczinger, András; Hornyánszky, Gábor; Zagyva, Imre

    2014-01-01

    The sequence of a phenylalanine ammonia-lyase (PAL; EC: 4.3.1.24) of the thermophilic and radiotolerant bacterium Rubrobacter xylanophilus (RxPAL) was identified by screening the genomes of bacteria for members of the phenylalanine ammonia-lyase family. A synthetic gene encoding the RxPAL protein was cloned and overexpressed in Escherichia coli TOP 10 in a soluble form with an N-terminal His6-tag and the recombinant RxPAL protein was purified by Ni-NTA affinity chromatography. The activity assay of RxPAL with l-phenylalanine at various pH values exhibited a local maximum at pH 8.5 and a global maximum at pH 11.5. Circular dichroism (CD) studies showed that RxPAL is associated with an extensive α-helical character (far UV CD) and two distinctive near-UV CD peaks. These structural characteristics were well preserved up to pH 11.0. The extremely high pH optimum of RxPAL can be rationalized by a three-dimensional homology model indicating possible disulfide bridges, extensive salt-bridge formation and an excess of negative electrostatic potential on the surface. Due to these properties, RxPAL may be a candidate as biocatalyst in synthetic biotransformations leading to unnatural l- or d-amino acids or as therapeutic enzyme in treatment of phenylketonuria or leukemia. PMID:24475062

  11. GPR139, an Orphan Receptor Highly Enriched in the Habenula and Septum, Is Activated by the Essential Amino Acids L-Tryptophan and L-Phenylalanine.

    PubMed

    Liu, Changlu; Bonaventure, Pascal; Lee, Grace; Nepomuceno, Diane; Kuei, Chester; Wu, Jiejun; Li, Qingqin; Joseph, Victory; Sutton, Steven W; Eckert, William; Yao, Xiang; Yieh, Lynn; Dvorak, Curt; Carruthers, Nicholas; Coate, Heather; Yun, Sujin; Dugovic, Christine; Harrington, Anthony; Lovenberg, Timothy W

    2015-11-01

    GPR139 is an orphan G-protein-coupled receptor expressed in the central nervous system. To identify its physiologic ligand, we measured GPR139 receptor activity from recombinant cells after treatment with amino acids, orphan ligands, serum, and tissue extracts. GPR139 activity was measured using guanosine 5'-O-(3-[(35)S]thio)-triphosphate binding, calcium mobilization, and extracellular signal-regulated kinases phosphorylation assays. Amino acids L-tryptophan (L-Trp) and L-phenylalanine (L-Phe) activated GPR139, with EC50 values in the 30- to 300-μM range, consistent with the physiologic concentrations of L-Trp and L-Phe in tissues. Chromatography of rat brain, rat serum, and human serum extracts revealed two peaks of GPR139 activity, which corresponded to the elution peaks of L-Trp and L-Phe. With the purpose of identifying novel tools to study GPR139 function, a high-throughput screening campaign led to the identification of a selective small-molecule agonist [JNJ-63533054, (S)-3-chloro-N-(2-oxo-2-((1-phenylethyl)amino)ethyl) benzamide]. The tritium-labeled JNJ-63533054 bound to cell membranes expressing GPR139 and could be specifically displaced by L-Trp and L-Phe. Sequence alignment revealed that GPR139 is highly conserved across species, and RNA sequencing studies of rat and human tissues indicated its exclusive expression in the brain and pituitary gland. Immunohistochemical analysis showed specific expression of the receptor in circumventricular regions of the habenula and septum in mice. Together, these findings suggest that L-Trp and L-Phe are candidate physiologic ligands for GPR139, and we hypothesize that this receptor may act as a sensor to detect dynamic changes of L-Trp and L-Phe in the brain. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

  12. Raspberry Ketone

    MedlinePlus

    ... raspberry ketone solution to the scalp might increase hair growth in people with hair loss. Male pattern baldness ( ... raspberry ketone solution to the scalp might increase hair growth in people with male pattern baldness Obesity. Early ...

  13. Rational engineering of multiple module pathways for the production of L-phenylalanine in Corynebacterium glutamicum.

    PubMed

    Zhang, Chuanzhi; Zhang, Junli; Kang, Zhen; Du, Guocheng; Chen, Jian

    2015-05-01

    Microbial production of L-phenylalanine (L-Phe) from renewable sources has attracted much attention recently. In the present study, Corynebacterium glutamicum 13032 was rationally engineered to produce L-Phe from inexpensive glucose. First, all the L-Phe biosynthesis pathway genes were investigated and the results demonstrated that in addition to AroF and PheA, the native PpsA, TktA, AroE and AroA, and the heterologous AroL and TyrB were also the key enzymes for L-Phe biosynthesis. Through combinational expression of these key enzymes, the L-Phe production was increased to 6.33 ± 0.13 g l(-1) which was about 1.48-fold of that of the parent strain C. glutamicum (pXM-pheA (fbr)-aroF (fbr)) (fbr, feedback-inhibition resistance). Furthermore, the production of L-Phe was improved to 9.14 ± 0.21 g l(-1) by modifying the glucose and L-Phe transport systems and blocking the acetate and lactate biosynthesis pathways. Eventually, the titer of L-Phe was enhanced to 15.76 ± 0.23 g l(-1) with a fed-batch fermentation strategy. To the best of our knowledge, this was the highest value reported in rationally engineered C. glutamicum 13032 strains. The results obtained will also contribute to rational engineering of C. glutamicum for production of other valuable aromatic compounds.

  14. 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.

  15. Sulphur and oxygen sequestration of n-C37 and n-C38 unsaturated ketones in an immature kerogen and the release of their carbon skeletons during early stages of thermal maturation

    USGS Publications Warehouse

    Koopmans, M.P.; Schaeffer-Reiss, C.; De Leeuw, J. W.; Lewan, M.D.; Maxwell, J.R.; Schaeffer, P.; Sinninghe, Damste J.S.

    1997-01-01

    Sedimentary rock from the Gessoso-solfifera Formation (Messinian) in the Vena del Gesso Basin (northern Italy) containing immature (Ro = 0.25%) S-rich organic matter was artificially matured by hydrous pyrolysis at temperatures from 160 to 330??C for 72 h to study the diagenetic fate of n-C37 and n-C38 di-and tri-unsaturated methyl and ethyl ketones (alkenones) biosynthesised by several prymnesiophyte algae. During early diagenesis, the alkenones are incorporated into the kerogen by both sulphur and oxygen cross-linking as indicated by chemical degradation experiments with the kerogen of the unheated sample. Heating at temperatures between 160 and 260??C, which still represents early stages of thermal maturation, produces large amounts (up to 1 mg/g TOC) of S-bound, O-bound, and both S-and O-bound n-C37 and n-C38 skeletons, saturated n-C37 and n-C38 methyl, ethyl, and mid-chain ketones, C37 and C38 mid-chain 2,5-di-n-alkylthiophenes, C37 and C38 1,2-di-n-alkylbenzenes, and C37 and C38 n-alkanes. With increasing thermal maturation, three forms of the n-C37 and n-C38 skeletons are relatively stable (saturated hydrocarbons, 1,2-di-n-alkylbenzenes and saturated ketones), whereas the S-and O-bound skeletons are relatively labile. These results suggest that in natural situations saturated ketones with an n-C37 and n-C38 skeleton can be expected as well as the corresponding hydrocarbons. Copyright ?? 1997 Elsevier Science Ltd.

  16. Sulphur and oxygen sequestration of n-C 37 and n-C 38 unsaturated ketones in an immature kerogen and the release of their carbon skeletons during early stages of thermal maturation

    NASA Astrophysics Data System (ADS)

    Koopmans, Martin P.; Schaeffer-Reiss, Christine; de Leeuw, Jan W.; Lewan, Michael D.; Maxwell, James R.; Schaeffer, Philippe; Sinninghe Damsté, Jaap S.

    1997-06-01

    Sedimentary rock from the Gessoso-solfifera Formation (Messinian) in the Vena del Gesso Basin (northern Italy) containing immature ( Ro = 0.25%) S-rich organic matter was artificially matured by hydrous pyrolysis at temperatures from 160 to 330°C for 72 h to study the diagenetic fate of n-C 37 and n-C 38 di- and tri-unsaturated methyl and ethyl ketones (alkenones) biosynthesised by several prymnesiophyte algae. During early diagenesis, the alkenones are incorporated into the kerogen by both sulphur and oxygen cross-linking as indicated by chemical degradation experiments with the kerogen of the unheated sample. Heating at temperatures between 160 and 260°C, which still represents early stages of thermal maturation, produces large amounts (up to 1 mg/g TOC) of S-bound, O-bound, and both S- and O-bound n-C 37 and n-C 38 skeletons, saturated n-C 37 and n-C38 methyl, ethyl, and mid-chain ketones, C 37 and C 38 mid-chain 2,5-di- n-alkylthiophenes, C 37 and C 38 1,2-di- n-alkylbenzenes, and C 37 and C 38n-alkanes. With increasing thermal maturation, three forms of the n-C 37 and n-C 38 skeletons are relatively stable (saturated hydrocarbons, 1,2-di- n-alkylbenzenes and saturated ketones), whereas the S- and O-bound skeletons are relatively labile. These results suggest that in natural situations saturated ketones with an n-C 37 and n-C 38 skeleton can be expected as well as the corresponding hydrocarbons.

  17. Photoactive ligands probing the sweet taste receptor. Design and synthesis of highly potent diazirinyl D-phenylalanine derivatives.

    PubMed

    Masuda, Katsuyoshi; Koizumi, Ayako; Misaka, Takumi; Hatanaka, Yasumaru; Abe, Keiko; Tanaka, Takaharu; Ishiguro, Masaji; Hashimoto, Makoto

    2010-02-01

    Some D-amino acids such as d-tryptophan and D-phenylalanine are well known as naturally-occurring sweeteners. Photoreactive D-phenylalanine derivatives containing trifluoromethyldiazirinyl moiety at 3- or 4-position of phenylalanine, were designed as sweeteners for functional analysis with photoaffinity labeling. The trifluoromethyldiazirinyl D-phenylalanine derivatives were prepared effectively with chemo-enzymatic methods using L-amino acid oxidase and were found to have potent activity toward the human sweet taste receptor. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

  18. A resolution approach of racemic phenylalanine with aqueous two-phase systems of chiral tropine ionic liquids.

    PubMed

    Wu, Haoran; Yao, Shun; Qian, Guofei; Yao, Tian; Song, Hang

    2015-10-30

    Aqueous two-phase systems (ATPS) based on tropine type chiral ionic liquids and inorganic salt solution were designed and prepared for the enantiomeric separation of racemic phenylalanine. The phase behavior of IL-based ATPS was comprehensive investigated, and phase equilibrium data were correlated by Merchuk equation. Various factors were also systematically investigated for their influence on separation efficiency. Under the appropriate conditions (0.13g/g [C8Tropine]pro, 35mg/g Cu(Ac)2, 20mg/g d,l-phenylalanine, 0.51g/g H2O and 0.30g/g K2HPO4), the enantiomeric excess value of phenylalanine in solid phase (mainly containing l-enantiomer) was 65%. Finally, the interaction mechanism was studied via 1D and 2D NMR. The results indicate that d-enantiomer of phenylalanine interacts more strongly with chiral ILs and Cu(2+) based on the chiral ion-pairs space coordination mechanism, which makes it tend to remain in the top IL-rich phase. By contrast, l-enantiomer is transferred into the solid phase. Above chiral ionic liquids aqueous two-phase systems have demonstrated obvious resolution to racemic phenylalanine and could be promising alterative resolution approach for racemic amino acids in aqueous circumstance. Copyright © 2015. Published by Elsevier B.V.

  19. Efficacy of 3,5-dibromo-L-phenylalanine in rat models of stroke, seizures and sensorimotor gating deficit

    PubMed Central

    Cao, W; Shah, HP; Glushakov, AV; Mecca, AP; Shi, P; Sumners, C; Seubert, CN; Martynyuk, AE

    2009-01-01

    Background and purpose: Abnormal glutamatergic activity is implicated in neurologic and neuropsychiatric disorders. Selective glutamate receptor antagonists were highly effective in animal models of stroke and seizures but failed in further clinical development because of serious side effects, including an almost complete set of symptoms of schizophrenia. Therefore, the novel polyvalent glutamatergic agent 3,5-dibromo-L-phenylalanine (3,5-DBr-L-Phe) was studied in rat models of stroke, seizures and sensorimotor gating deficit. Experimental approach: 3,5-DBr-L-Phe was administered intraperitoneally as three boluses after intracerebral injection of endothelin-1 (ET-1) adjacent to the middle cerebral artery to cause brain injury (a model of stroke). 3,5-DBr-L-Phe was also given as a single bolus prior to pentylenetetrazole (PTZ) injection to induce seizures or prior to the administration of the N-methyl-D-aspartate (NMDA) receptor antagonist dizocilpine (MK-801) to cause disruption of prepulse inhibition (PPI) of startle (sensorimotor gating deficit). Key results: Brain damage caused by ET-1 was reduced by 52%, which is comparable with the effects of MK-801 in this model as reported by others. 3,5-DBr-L-Phe significantly reduced seizures induced by PTZ without the significant effects on arterial blood pressure and heart rate normally caused by NMDA antagonists. 3,5-DBr-L-Phe prevented the disruption of PPI measured 3 days after the administration of ET-1. 3,5-DBr-L-Phe also eliminated sensorimotor gating deficit caused by MK-801. Conclusion and implications: The pharmacological profile of 3,5-DBr-L-Phe might be beneficial not only for developing a therapy for the neurological and cognitive symptoms of stroke and seizures but also for some neuropsychiatric disorders. PMID:20050189

  20. Thermal, mechanical, optical and conductivity studies of a novel NLO active L-phenylalanine L-phenylalaninium dihydrogenphosphate single crystal

    NASA Astrophysics Data System (ADS)

    Sujatha, T.; Cyrac Peter, A.; Vimalan, M.; Merline Shyla, J.; Madhavan, J.

    2010-08-01

    An efficient, novel, semi-organic, nonlinear optical (NLO) material L-phenylalanine L-phenylalaninium dihydrogenphosphate (LPADHP), single crystal of dimension 11×5×2 mm 3, has been grown by the slow evaporation solution growth technique. Single crystal X-ray diffraction studies confirm that the grown crystal belongs to monoclinic system with the space group P2 1. The functional groups present in the crystal were confirmed by the Fourier transform infrared technique. Optical absorption spectrum shows that the material possesses very low absorption in the entire visible region. Thermal analysis confirmed that the crystal is thermally stable up to 161 °C. The frequency dependent dielectric properties of the grown crystal were studied for various temperatures. The second harmonic generation (SHG) efficiency of the grown crystal is 1.2 times greater than that of the potassium dihydrogenphosphate (KDP) single crystal. The laser induced surface damage threshold for the grown crystal was found to be 6.3 GW cm -2 with Nd:YAG laser assembly AC and DC conductivity and photoconductivity experiments are also carried out and the results are discussed.

  1. Spectroscopic analyses on interaction of o-Vanillin-D-Phenylalanine, o-Vanillin-L-Tyrosine and o-Vanillin-L-Levodopa Schiff Bases with bovine serum albumin (BSA).

    PubMed

    Gao, Jingqun; Guo, Yuwei; Wang, Jun; Wang, Zhiqiu; Jin, Xudong; Cheng, Chunping; Li, Ying; Li, Kai

    2011-04-01

    In this work, three o-Vanillin Schiff Bases (o-VSB: o-Vanillin-D-Phenylalanine (o-VDP), o-Vanillin-L-Tyrosine (o-VLT) and o-Vanillin-L-Levodopa (o-VLL)) with alanine constituent were synthesized by direct reflux method in ethanol solution, and then were used to study the interaction to bovine serum albumin (BSA) molecules by fluorescence spectroscopy. Based on the fluorescence quenching calculation, the bimolecular quenching constant (K(q)), apparent quenching constant (K(sv)), effective binding constant (K(A)) and corresponding dissociation constant (K(D)) as well as binding site number (n) were obtained. In addition, the binding distance (r) was also calculated according to Foster's non-radioactive energy transfer theory. The results show that these three o-VSB can efficiently bind to BSA molecules, but the binding array order is o-VDP-BSA>o-VLT-BSA>o-VLL-BSA. Synchronous fluorescence spectroscopy indicates that the o-VDP is more accessibility to tryptophan (Trp) residues of BSA molecules than to tyrosine (Tyr) residues. Nevertheless, the o-VLT and o-VLL are more accessibility to Tyr residues than to Trp residues. Copyright © 2010 Elsevier B.V. All rights reserved.

  2. The influence of L-phenylalanine, methyl jasmonate and sucrose concentration on the accumulation of phenolic acids in Exacum affine Balf. f. ex Regel shoot culture.

    PubMed

    Skrzypczak-Pietraszek, Ewa; Słota, Joanna; Pietraszek, Jacek

    2014-01-01

    Phenolic acids are an important group of plant secondary metabolites with various, valuable therapeutic properties. Apart from plants growing in the open air, tissue cultures can be an alternative source of the secondary metabolites. The yield of their accumulation in in vitro cultures can be increased by different methods, including culture medium supplementation with precursors, elicitors and changing the standard amounts of the medium components. The purpose of this study was to investigate the influence of the precursor (L-phenylalanine), the elicitor (methyl jasmonate) and a higher sucrose concentration on the phenolic acids accumulation in the agitated shoot cultures of Exacum affine Balf. f. ex Regel (Gentianaceae). Qualitative and quantitative analyses of the phenolic acids in methanolic extracts from the biomass were conducted by applying the HPLC method. Fourteen phenolic acids and cinnamic acid were found in all samples. The total content of free phenolic acids increased from approximately 0.242% to 0.635% (2.6-fold) and the total content of the whole phenolic acids (free and bound) - from 0.712% to 1.160% (1.6-fold). The studies show that the best variant for the accumulation of most of the identified phenolic acids contained 6% of sucrose (double the standard amount), L-phenylalanine 1.6 gL(-1) of medium and methyl jasmonate 100 μM. The analysis of the results in the experiment presented here showed that it is possible to increase the accumulation of the phenolic acids in Exacum affine shoot cultures - by adding the precursor (L-phenylalanine), the elicitor (methyl jasmonate) and by increasing the sucrose concentration.

  3. l-phenylalanine modulates gut hormone release and glucose tolerance, and suppresses food intake through the calcium-sensing receptor in rodents.

    PubMed

    Alamshah, A; Spreckley, E; Norton, M; Kinsey-Jones, J S; Amin, A; Ramgulam, A; Cao, Y; Johnson, R; Saleh, K; Akalestou, E; Malik, Z; Gonzalez-Abuin, N; Jomard, A; Amarsi, R; Moolla, A; Sargent, P R; Gray, G W; Bloom, S R; Murphy, K G

    2017-11-01

    High-protein diets (HPDs) are associated with greater satiety and weight loss than diets rich in other macronutrients. The exact mechanisms by which HPDs exert their effects are unclear. However, evidence suggests that the sensing of amino acids produced as a result of protein digestion may have a role in appetite regulation and satiety. We investigated the effects of l-phenylalanine (L-Phe) on food intake and glucose homeostasis in rodents. We investigated the effects of the aromatic amino-acid and calcium-sensing receptor (CaSR) agonist l-phenylalanine (L-Phe) on food intake and the release of the gastrointestinal (GI) hormones peptide YY (PYY), glucagon-like peptide-1 (GLP-1) and ghrelin in rodents, and the role of the CaSR in mediating these effects in vitro and in vivo. We also examined the effect of oral l-Phe administration on glucose tolerance in rats. Oral administration of l-Phe acutely reduced food intake in rats and mice, and chronically reduced food intake and body weight in diet-induced obese mice. Ileal l-Phe also reduced food intake in rats. l-Phe stimulated GLP-1 and PYY release, and reduced plasma ghrelin, and also stimulated insulin release and improved glucose tolerance in rats. Pharmacological blockade of the CaSR attenuated the anorectic effect of intra-ileal l-Phe in rats, and l-Phe-induced GLP-1 release from STC-1 and primary L cells was attenuated by CaSR blockade. l-Phe reduced food intake, stimulated GLP-1 and PYY release, and reduced plasma ghrelin in rodents. Our data provide evidence that the anorectic effects of l-Phe are mediated via the CaSR, and suggest that l-Phe and the CaSR system in the GI tract may have therapeutic utility in the treatment of obesity and diabetes. Further work is required to determine the physiological role of the CaSR in protein sensing in the gut, and the role of this system in humans.

  4. The serine protease inhibitor TLCK attenuates intrinsic death pathways in neurons upstream of mitochondrial demise.

    PubMed

    Reuther, C; Ganjam, G K; Dolga, A M; Culmsee, C

    2014-11-01

    It is well-established that activation of proteases, such as caspases, calpains and cathepsins are essential components in signaling pathways of programmed cell death (PCD). Although these proteases have also been linked to mechanisms of neuronal cell death, they are dispensable in paradigms of intrinsic death pathways, e.g. induced by oxidative stress. However, emerging evidence implicated a particular role for serine proteases in mechanisms of PCD in neurons. Here, we investigated the role of trypsin-like serine proteases in a model of glutamate toxicity in HT-22 cells. In these cells glutamate induces oxytosis, a form of caspase-independent cell death that involves activation of the pro-apoptotic protein BH3 interacting-domain death agonist (Bid), leading to mitochondrial demise and ensuing cell death. In this model system, the trypsin-like serine protease inhibitor Nα-tosyl-l-lysine chloromethyl ketone hydrochloride (TLCK) inhibited mitochondrial damage and cell death. Mitochondrial morphology alterations, the impairment of the mitochondrial membrane potential and ATP depletion were prevented and, moreover, lipid peroxidation induced by glutamate was completely abolished. Strikingly, truncated Bid-induced cell death was not affected by TLCK, suggesting a detrimental activity of serine proteases upstream of Bid activation and mitochondrial demise. In summary, this study demonstrates the protective effect of serine protease inhibition by TLCK against oxytosis-induced mitochondrial damage and cell death. These findings indicate that TLCK-sensitive serine proteases play a crucial role in cell death mechanisms upstream of mitochondrial demise and thus, may serve as therapeutic targets in diseases, where oxidative stress and intrinsic pathways of PCD mediate neuronal cell death.

  5. Ketone Bodies in Epilepsy

    PubMed Central

    McNally, Melanie A.; Hartman, Adam L.

    2014-01-01

    Seizures that are resistant to standard medications remain a major clinical problem. One underutilized option for patients with medication-resistant seizures is the high-fat, low-carbohydrate ketogenic diet. The diet received its name based on the observation that patients consuming this diet produce ketone bodies (e.g., acetoacetate, β-hydroxybutyrate, and acetone). Although the exact mechanisms of the diet are unknown, ketone bodies have been hypothesized to contribute to the anticonvulsant and antiepileptic effects. In this review, anticonvulsant properties of ketone bodies and the ketogenic diet are discussed (including GABAergic and glutamatergic effects). Because of the importance of ketone body metabolism in the early stages of life, the effects of ketone bodies on developing neurons in vitro also are discussed. Understanding how ketone bodies exert their effects will help optimize their use in treating epilepsy and other neurological disorders. PMID:22268909

  6. 4-Cyano-α-methyl-l-phenylalanine as a spectroscopic marker for the investigation of peptaibiotic-membrane interactions.

    PubMed

    De Zotti, Marta; Bobone, Sara; Bortolotti, Annalisa; Longo, Edoardo; Biondi, Barbara; Peggion, Cristina; Formaggio, Fernando; Toniolo, Claudio; Dalla Bona, Andrea; Kaptein, Bernard; Stella, Lorenzo

    2015-04-01

    Two analogs of the ten-amino acid residue, membrane-active lipopeptaibiotic trichogin GA IV, mono-labeled with 4-cyano-α-methyl-L-phenylalanine, a potentially useful fluorescence and IR absorption probe of the local microenvironment, were synthesized by the solid-phase methodology and conformationally characterized. The single modification was incorporated either at the N-terminus (position 1) or near the C-terminus (position 8) of the peptide main chain. In both cases, the replaced amino acid was the equally helicogenic α-aminoisobutyric acid (Aib) residue. We performed a solution conformational analysis by use of FT-IR absorption, CD, and 2D-NMR spectroscopies. The results indicate that both labeled analogs essentially maintain the overall helical propensity of the naturally occurring lipopeptaibiotic. Peptide-membrane interactions were assessed by fluorescence and ATR-IR absorption techniques. Analogies and differences between the two peptides were highlighted. Taken together, our data confirm literature results that some of the spectroscopic parameters of the 4-cyanobenzyl chromophore are sensitive markers of the local microenvironment. Copyright © 2015 Verlag Helvetica Chimica Acta AG, Zürich.

  7. Infrared and Raman spectra of N-acetyl- L-amino acid methylamides with aromatic side groups

    NASA Astrophysics Data System (ADS)

    Matsuura, Hiroatsu; Hasegawa, Kodo; Miyazawa, Tatsuo

    Infrared and Raman spectra of N-acetyl- L-phenylalanine methylamide, N-acetyl- L-tyrosine methylamide and N-acetyl- L-tryptophan methylamide, as model compounds of aromatic amino acid residues in proteins, were measured in the solid state and in methanol solutions. Vibrational assignments of the spectra were made by utilizing the deuteration effect and by comparison with the spectra of related compounds which include toluene, p-cresol and 3-methylindole. The amide I, III and IV bands were strong in Raman scattering, but other characteristic amide bands were ill-defined. In the Raman spectra of methanol solutions, only the bands due to the aromatic side group vibrations were markedly observed, but those due to the peptide backbone vibrations were very weak, suggesting the coexistence of various molecular conformations in solution.

  8. Determination of L-phenylalanine on-line based on molecularly imprinted polymeric microspheres and flow injection chemiluminescence

    NASA Astrophysics Data System (ADS)

    Qiu, Huamin; Xi, Yulei; Lu, Fuguang; Fan, Lulu; Luo, Chuannan

    2012-02-01

    A novel molecular imprinting-chemiluminescence (MIP-CL) sensor for the determination of L-phenylalanine (Phe) using molecularly imprinted polymer (MIP) as recognition element is reported. The Phe-MIP was synthesized using acrylamide (AM) as functional monomer and ethylene glycol dimethacrylate (EGDMA) as cross-linker, 2,2-azobisisobutyronitrile (AIBN) as initiator and the polymers' properties were characterized. Then the synthesized MIP was employed as recognition element by packing into flow cell to establish a novel flow injection CL sensor. The CL intensity responded linearly to the concentration of Phe in the range 1.3 × 10 -6 to 5.44 × 10 -4 mol/L with a detection limit of 6.23 × 10 -7 mol/L (3 σ), which is lower than that of conventional methods. The sensor is reusable and has a great improvement in sensitivity and selectivity for CL analysis. As a result, the new MIP-CL sensor had been successfully applied to the determination of Phe in samples.

  9. Influence of functional groups on the C α-C β chain of L-phenylalanine and its derivatives

    NASA Astrophysics Data System (ADS)

    Ganesan, Aravindhan; Brunger, Michael; Wang, Feng

    2010-07-01

    L-phenylalanine ( L-phe) consists of three different functional groups, i.e., phenyl, carboxyl (-COOH) and amino (-NH 2), joining through the C α-C β bridge. Substitution of these groups produces 2-phenethylamine (PEA) and 3-phenylpropionic acid (PPA). Electronic structures of L-phe, PEA and PPA together with smaller "fragments" L-alanine and benzene were determined using density functional theory (DFT), from which core and valence shell ionization spectra were simulated. Comparison of the spectra reveals that core shell ionization energies clearly indicate that the carbon bridge is significantly affected by their functional group substitutions particularly at the C α site. In the valence space, quite unexpectedly, the frontier orbitals are concentrated on the benzene group although some energy splitting is observed. The orbitals which significantly affect the C α-C β carbon backbone are from the inner valence shell in the ionization energy region of 20-26 eV of the molecules.

  10. Ketone bodies in epilepsy.

    PubMed

    McNally, Melanie A; Hartman, Adam L

    2012-04-01

    Seizures that are resistant to standard medications remain a major clinical problem. One underutilized option for patients with medication-resistant seizures is the high-fat, low-carbohydrate ketogenic diet. The diet received its name based on the observation that patients consuming this diet produce ketone bodies (e.g., acetoacetate, β-hydroxybutyrate, and acetone). Although the exact mechanisms of the diet are unknown, ketone bodies have been hypothesized to contribute to the anticonvulsant and antiepileptic effects. In this review, anticonvulsant properties of ketone bodies and the ketogenic diet are discussed (including GABAergic and glutamatergic effects). Because of the importance of ketone body metabolism in the early stages of life, the effects of ketone bodies on developing neurons in vitro also are discussed. Understanding how ketone bodies exert their effects will help optimize their use in treating epilepsy and other neurological disorders. © 2012 The Authors. Journal of Neurochemistry © 2012 International Society for Neurochemistry.

  11. Regulation of Hippocampal Glutamate Receptors: Evidence for the Involvement of a Calcium-Activated Protease

    NASA Astrophysics Data System (ADS)

    Baudry, Michel; Lynch, Gary

    1980-04-01

    Specific [3H]glutamate binding to rat hippocampal membranes and the calcium-induced increase in this binding are markedly temperature-sensitive and are inhibited by alkylating or reducing agents as well as by various protease inhibitors. N-Ethylmaleimide, chloromethyl ketone derivatives of lysine and phenylalanine, and tosylarginine methyl ester decrease the maximum number of [3H]glutamate binding sites without changing their affinity for glutamate. Preincubation of the membranes with glutamate does not protect the glutamate ``receptors'' from the suppressive effects of these agents. The proteases trypsin and α -chymotrypsin increase the maximum number of [3H]glutamate binding sites. The effects of calcium on glutamate binding are different across brain regions. Cerebellar membranes are almost insensitive whereas hippocampal and striatal membranes exhibit a strong increase in the number of binding sites after exposure to even low concentrations of calcium. These results suggest that an endogenous membrane-associated thiol protease regulates the number of [3H]glutamate binding sites in hippocampal membranes and that this is the mechanism by which calcium stimulates glutamate binding. The possibility is discussed that the postulated mechanisms participate in synaptic physiology and in particular may be related to the long-term potentiation of transmission found in hippocampus under certain conditions.

  12. Synthesis of d‐ and l‐Phenylalanine Derivatives by Phenylalanine Ammonia Lyases: A Multienzymatic Cascade Process†

    PubMed Central

    Parmeggiani, Fabio; Lovelock, Sarah L.; Weise, Nicholas J.; Ahmed, Syed T.

    2015-01-01

    Abstract The synthesis of substituted d‐phenylalanines in high yield and excellent optical purity, starting from inexpensive cinnamic acids, has been achieved with a novel one‐pot approach by coupling phenylalanine ammonia lyase (PAL) amination with a chemoenzymatic deracemization (based on stereoselective oxidation and nonselective reduction). A simple high‐throughput solid‐phase screening method has also been developed to identify PALs with higher rates of formation of non‐natural d‐phenylalanines. The best variants were exploited in the chemoenzymatic cascade, thus increasing the yield and ee value of the d‐configured product. Furthermore, the system was extended to the preparation of those l‐phenylalanines which are obtained with a low ee value using PAL amination. PMID:27478261

  13. Fluorometric and theoretical studies on inclusion complexes of β-cyclodextrin and D-, L-phenylalanine

    NASA Astrophysics Data System (ADS)

    Aree, Thammarat; Arunchai, Rungthiwa; Koonrugsa, Narongsak; Intasiri, Amarawan

    2012-10-01

    Inclusion complexes of β-cyclodextrin (β-CD) with L- and D-phenylalanine (Phe) have been characterized in solution by fluorometry and in gas phase by semiempirical PM3 calculations. The unimolar stoichiometric ratio of both β-CD-L-Phe and β-CD-D-Phe complexes and the stability constants (K) were deduced from fluorometric titrations. The β-CD-L-Phe complex is more stable than the β-CD-D-Phe complex as indicated by the larger K values, 21.1 vs. 6.86 M-1. This is consistent with the stabilization energies (ΔEstb) and inclusion geometries obtained from PM3 calculations. The β-CD-L-Phe complex with L-Phe residing in the central β-CD cavity and pointing its COOH group downwards to the O6 end has ΔEstb = -62.7 kJ mol-1, whereas the β-CD-D-Phe complex with D-Phe placing at 3 Å beneath the β-CD O4-plane and pointing its COOH group upwards to the O2/O3 end has ΔEstb = -53.3 kJ mol-1. The unison of host-guest intermolecular hydrogen bonds, hydrophobic interactions and molecular deformations plays an essential role in forming and stabilizing the inclusion complexes. Our results show that the β-CD-L-Phe and β-CD-D-Phe inclusion complexes are relatively stable and differentiable, suggesting the applications of CDs in foods and drugs.

  14. Cu(I)-catalyzed transannulation of N-heteroaryl aldehydes or ketones with alkylamines via C(sp3)-H amination.

    PubMed

    Li, Mingyang; Xie, Ying; Ye, Yong; Zou, Yong; Jiang, Huanfeng; Zeng, Wei

    2014-12-05

    A copper(I)-catalyzed direct transannulation of N-heteroaryl aldehydes or ketones with alkylamines via Csp(3)-H amination has been achieved using molecular oxygen as a sole oxidant. N-Heteroarenes are employed as the amine source. This transformation provides a rapid and concise access to multifunctional imidazo[1,5-a]pyridines.

  15. Antioxidant capacity contributes to protection of ketone bodies against oxidative damage induced during hypoglycemic conditions.

    PubMed

    Haces, María L; Hernández-Fonseca, Karla; Medina-Campos, Omar N; Montiel, Teresa; Pedraza-Chaverri, José; Massieu, Lourdes

    2008-05-01

    Ketone bodies play a key role in mammalian energy metabolism during the suckling period. Normally ketone bodies' blood concentration during adulthood is very low, although it can rise during starvation, an exogenous infusion or a ketogenic diet. Whenever ketone bodies' levels increase, their oxidation in the brain rises. For this reason they have been used as protective molecules against refractory epilepsy and in experimental models of ischemia and excitotoxicity. The mechanisms underlying the protective effect of these compounds are not completely understood. Here, we studied a possible antioxidant capacity of ketone bodies and whether it contributes to the protection against oxidative damage induced during hypoglycemia. We report for the first time the scavenging capacity of the ketone bodies, acetoacetate (AcAc) and both the physiological and non-physiological isomers of beta-hydroxybutyrate (D- and L-BHB, respectively), for diverse reactive oxygen species (ROS). Hydroxyl radicals (.OH) were effectively scavenged by D- and L-BHB. In addition, the three ketone bodies were able to reduce cell death and ROS production induced by the glycolysis inhibitor, iodoacetate (IOA), while only D-BHB and AcAc prevented neuronal ATP decline. Finally, in an in vivo model of insulin-induced hypoglycemia, the administration of D- or L-BHB, but not of AcAc, was able to prevent the hypoglycemia-induced increase in lipid peroxidation in the rat hippocampus. Our data suggest that the antioxidant capacity contributes to protection of ketone bodies against oxidative damage in in vitro and in vivo models associated with free radical production and energy impairment.

  16. Identification of a serine protease as a major allergen (Per a 10) of Periplaneta americana.

    PubMed

    Sudha, V T; Arora, N; Gaur, S N; Pasha, S; Singh, B P

    2008-06-01

    Cockroach allergens are associated with the development of asthma, but none of these has been characterized for proteolytic activity. This study was undertaken to isolate and characterize a protease from Periplaneta americana and determine its allergenicity. A serine protease was isolated from P. americana extract using benzamidine sepharose column and characterized by immunobiochemical methods. Allergenicity of the protease was assessed by enzyme-linked immunosorbent assay, immunoblot, intradermal testing, histamine release and peripheral blood mononuclear cells (PBMCs) proliferation. Affinity purified protein of approximately 28 kDa (Per a 10) showed a single band of activity in gelatin zymogram and agarose plate assay. N-terminal sequence (IVGGRPAQI) revealed similarity with mite serine protease allergens and insect trypsins. It demonstrated proteolytic activity with azocollagen > gelatin > defatted-milk > casein including serine protease specific substrate, N-benzoyl-arginine-ethyl-ester-hydrochloride. It was inhibited by serine protease inhibitors, namely aprotinin > pefabloc > AEBSF > PMSF > benzamidine > antipain > leupeptin and trypsin-specific inhibitor (tosyl-lysyl-chloromethyl-ketone) suggesting it to be a trypsin-like serine protease. Per a 10 was recognized as a major allergen, showing IgE reactivity with >80% of cockroach sensitized patients by skin tests and immunoblot. It could induce significant histamine release (P < 0.05) in blood and secretion of interleukin-4 (IL-4) (P < 0.05) and IL-5 (P < 0.05) in culture supernatant of PBMCs from cockroach hypersensitive patients, suggesting a strong allergenic potency. A serine protease isolated from P. americana was demonstrated to be a major allergen (Per a 10). It has a potential for component-based diagnosis of allergy and will be useful in elucidating the mechanism of allergy.

  17. Vibrational spectra, optical properties, NBO and HOMO-LUMO analysis of L-Phenylalanine L-Phenylalaninium Perchlorate: DFT calculations

    NASA Astrophysics Data System (ADS)

    Elleuch, Nabil; Ben Ahmed, Ali; Feki, Habib; Abid, Younes; Minot, Christian

    2014-03-01

    In this work, we report a combined experimental and theoretical study of a nonlinear optical material, L-Phenylalanine L-Phenylalaninium Perchlorate. Single crystals of the title compound have been grown by slow evaporation of an aqueous solution at room temperature. Theoretical calculations were preceded by redetermination of the crystal X-ray structure. The compound crystallizes in the non-centro symmetric space group P212121 of the orthorhombic system. The FT-IR and Raman spectra of the crystal were recorded and analyzed. The density functional theory (DFT) computations have been performed at B3LYP/6-31G(d) level to derive equilibrium geometry, vibrational wavenumbers, intensity and NLO properties. All observed vibrational bands have been discussed and assigned to normal mode or to combinations on the basis of our DFT calculations as a primary source of attribution and also by comparison with the previous results for similar compounds. Natural bond orbital analysis was carried out to demonstrate the various inter-and intramolecular interaction that are responsible of the stabilization of the compound. The lowering of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy gap appears to be the cause of its enhanced charge transfer interaction leading to high NLO activity.

  18. Experimental determination of the carboxylate oxygen electric-field-gradient and chemical shielding tensors in L-alanine and L-phenylalanine

    NASA Astrophysics Data System (ADS)

    Yamada, Kazuhiko; Asanuma, Miwako; Honda, Hisashi; Nemoto, Takahiro; Yamazaki, Toshio; Hirota, Hiroshi

    2007-10-01

    We report a solid-state 17O NMR study of the 17O electric-field-gradient (EFG) and chemical shielding (CS) tensors for each carboxylate group in polycrystalline L-alanine and L-phenylalanine. The magic angle spinning (MAS) and stationary 17O NMR spectra of these compounds were obtained at 9.4, 14.1, and 16.4 T. Analyzes of these 17O NMR spectra yielded reliable experimental NMR parameters including 17O CS tensor components, 17O quadrupole coupling parameters, and the relative orientations between the 17O CS and EFG tensors. The extensive quantum chemical calculations at both the restricted Hartree-Fock and density-functional theories were carried out with various basis sets to evaluate the quality of quantum chemical calculations for the 17O NMR tensors in L-alanine. For 17O CS tensors, the calculations at the B3LYP/D95 ∗∗ level could reasonably reproduce 17O CS tensors, but they still showed some discrepancies in the δ11 components by approximately 36 ppm. For 17O EFG calculations, it was advantageous to use calibrated Q value to give acceptable CQ values. The calculated results also demonstrated that not only complete intermolecular hydrogen-bonding networks to target oxygen in L-alanine, but also intermolecular interactions around the NH3+ group were significant to reproduce the 17O NMR tensors.

  19. Bioconversion of L-phenylalanine to 2-phenylethanol by the novel stress-tolerant yeast Candida glycerinogenes WL2002-5

    PubMed Central

    Lu, Xinyao; Wang, Yuqin; Zong, Hong; Ji, Hao; Zhuge, Bin; Dong, Zhuoli

    2016-01-01

    ABSTRACT 2-Phenylethanol (2-PE) is a high value aromatic alcohol with a rose-like odor that is utilized in the cosmetics and other industries. Although the chemical routes of 2-PE production have been altered by some microbial transformation processes, the poor tolerance to organic solvents of these microorganisms has limited the 2-PE yield. In this study, the stress-tolerant yeast Candida glycerinogenes WL2002-5 showed a 2-PE tolerance to 4 g/l, which is the highest reported to date. Moreover, the 2-PE titer in a batch fermentation from L-phenylalanine reached 5g/l, which is the highest level achieved by fermentation without in situ product recovery. These results suggest C. glycerinogenes WL2002-5 is a robust strain for the bioproduction of 2-PE with potential for commercial exploitation. PMID:27435817

  20. Bioconversion of L-phenylalanine to 2-phenylethanol by the novel stress-tolerant yeast Candida glycerinogenes WL2002-5.

    PubMed

    Lu, Xinyao; Wang, Yuqin; Zong, Hong; Ji, Hao; Zhuge, Bin; Dong, Zhuoli

    2016-11-01

    2-Phenylethanol (2-PE) is a high value aromatic alcohol with a rose-like odor that is utilized in the cosmetics and other industries. Although the chemical routes of 2-PE production have been altered by some microbial transformation processes, the poor tolerance to organic solvents of these microorganisms has limited the 2-PE yield. In this study, the stress-tolerant yeast Candida glycerinogenes WL2002-5 showed a 2-PE tolerance to 4 g/l, which is the highest reported to date. Moreover, the 2-PE titer in a batch fermentation from L-phenylalanine reached 5g/l, which is the highest level achieved by fermentation without in situ product recovery. These results suggest C. glycerinogenes WL2002-5 is a robust strain for the bioproduction of 2-PE with potential for commercial exploitation.

  1. Routine production of [(18)f]flumazenil from iodonium tosylate using a sample pretreatment method: a 2.5-year production report.

    PubMed

    Moon, Byung Seok; Park, Jun Hyung; Lee, Hong Jin; Lee, Byung Chul; Kim, Sang Eun

    2014-10-01

    [(18)F]Flumazenil, which has the advantage of a longer half-life than [(11)C]flumazenil, is well known for determining of the central benzodiazepine receptor concentrations. However, [(18)F]flumazenil has not been widely used because fluctuating and relatively low yields render automatic production insufficient for routine and multicenter clinical trials. Here, we describe the results of a 2.5-year production study of [(18)F]flumazenil using an iodonium tosylate precursor, which allowed us to overcome the limitations of low and fluctuating radiochemical yields. We developed a clinically applicable production system by modifying a commercial synthesizer for the reliable and reproducible production of [(18)F]flumazenil for routine clinical studies. [(18)F]Flumazenil was prepared at 150 °C for 5 min in the presence of 4-methylphenyl-mazenil iodonium tosylate (4 mg), a radical scavenger (TEMPO, 1 mg), and [(18)F]KF/kryptofix 2.2.2 complex in N,N-dimethylformamide (1 ml). In the purification step, the final mixture was pretreated using different cartridges before performing high-performance liquid chromatography (HPLC) separation. Finally, we measured the radiochemical yield and performed quality-control assays on 94 batches. After carrying out additional purification before HPLC separation using a C18 plus Sep-Pak cartridge, the radiochemical yield of [(18)F]flumazenil increased from 34.4 ± 9.7 % (without the pretreatment, n = 24) to 53.4 ± 9.0 % (n = 94), and the lifetime of the semi-preparative column was five times that of the column without the C18 plus Sep-Pak cartridge. The mean-specific activity of [(18)F]flumazenil was 572 ± 116 GBq/μmol at the end of synthesis, and the radiochemical purity was more than 99 %, as determined by analytical HPLC and radio-TLC. [(18)F]Flumazenil prepared using this method satisfied all quality-control test standards and was highly stable for up to 6 h after preparation. The results of the 2.5-year

  2. Phenylalanine ammonia lyase catalyzed synthesis of amino acids by an MIO-cofactor independent pathway.

    PubMed

    Lovelock, Sarah L; Lloyd, Richard C; Turner, Nicholas J

    2014-04-25

    Phenylalanine ammonia lyases (PALs) belong to a family of 4-methylideneimidazole-5-one (MIO) cofactor dependent enzymes which are responsible for the conversion of L-phenylalanine into trans-cinnamic acid in eukaryotic and prokaryotic organisms. Under conditions of high ammonia concentration, this deamination reaction is reversible and hence there is considerable interest in the development of PALs as biocatalysts for the enantioselective synthesis of non-natural amino acids. Herein the discovery of a previously unobserved competing MIO-independent reaction pathway, which proceeds in a non-stereoselective manner and results in the generation of both L- and D-phenylalanine derivatives, is described. The mechanism of the MIO-independent pathway is explored through isotopic-labeling studies and mutagenesis of key active-site residues. The results obtained are consistent with amino acid deamination occurring by a stepwise E1 cB elimination mechanism. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. [Effect of phenolic ketones on ethanol fermentation and cellular lipid composition of Pichia stipitis].

    PubMed

    Yang, Jinlong; Cheng, Yichao; Zhu, Yuanyuan; Zhu, Junjun; Chen, Tingting; Xu, Yong; Yong, Qiang; Yu, Shiyuan

    2016-02-01

    Lignin degradation products are toxic to microorganisms, which is one of the bottlenecks for fuel ethanol production. We studied the effects of phenolic ketones (4-hydroxyacetophenone, 4-hydroxy-3-methoxy-acetophenone and 4-hydroxy-3,5-dimethoxy-acetophenone) derived from lignin degradation on ethanol fermentation of xylose and cellular lipid composition of Pichia stipitis NLP31. Ethanol and the cellular fatty acid of yeast were analyzed by high performance liquid chromatography (HPLC) and gas chromatography/mass spectrometry (GC/MS). Results indicate that phenolic ketones negatively affected ethanol fermentation of yeast and the lower molecular weight phenolic ketone compound was more toxic. When the concentration of 4-hydroxyacetophenone was 1.5 g/L, at fermentation of 24 h, the xylose utilization ratio, ethanol yield and ethanol concentration decreased by 42.47%, 5.30% and 9.76 g/L, respectively, compared to the control. When phenolic ketones were in the medium, the ratio of unsaturated fatty acids to saturated fatty acids (UFA/SFA) of yeast cells was improved. When 1.5 g/L of three aforementioned phenolic ketones was added to the fermentation medium, the UFA/SFA ratio of yeast cells increased to 3.03, 3.06 and 3.61, respectively, compared to 2.58 of the control, which increased cell membrane fluidity and instability. Therefore, phenolic ketones can reduce the yeast growth, increase the UFA/SFA ratio of yeast and lower ethanol productivity. Effectively reduce or remove the content of lignin degradation products is the key to improve lignocellulose biorefinery.

  4. Crystal growth, structural, optical, dielectric and thermal studies of an amino acid based organic NLO material: L-phenylalanine L-phenylalaninium malonate.

    PubMed

    Prakash, M; Geetha, D; Caroline, M Lydia; Ramesh, P S

    2011-12-01

    Good transparent single crystals of L-phenylalanine L-phenylalaninium malonate (LPPMA) have been grown successfully by slow evaporation technique from aqueous solution. Single crystal X-ray diffractometer was utilized to measure unit cell parameter and to confirm the crystal structure. The chemical structure of compound was established by FT-NMR technique. The vibrational modes of the molecules of elucidated from FTIR spectra. Its optical behaviour has been examined by UV-vis spectral analysis, which shows the absence of absorbance in the visible region. Thermal properties of the LPPMA crystal were carried out by thermo gravimetric analysis (TGA) and differential thermal analysis (DTA) techniques, which indicate that the material does not decompose before melting. The melting point of grown crystal was observed as 180°C by melting point apparatus. The NLO property was confirmed by the powder technique of Kurtz and Perry. The dielectric behaviour of the sample was also studied for the first time. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. Crystal growth, structural, optical, dielectric and thermal studies of an amino acid based organic NLO material: L-Phenylalanine L-phenylalaninium malonate

    NASA Astrophysics Data System (ADS)

    Prakash, M.; Geetha, D.; Lydia Caroline, M.; Ramesh, P. S.

    2011-12-01

    Good transparent single crystals of L-phenylalanine L-phenylalaninium malonate (LPPMA) have been grown successfully by slow evaporation technique from aqueous solution. Single crystal X-ray diffractometer was utilized to measure unit cell parameter and to confirm the crystal structure. The chemical structure of compound was established by FT-NMR technique. The vibrational modes of the molecules of elucidated from FTIR spectra. Its optical behaviour has been examined by UV-vis spectral analysis, which shows the absence of absorbance in the visible region. Thermal properties of the LPPMA crystal were carried out by thermo gravimetric analysis (TGA) and differential thermal analysis (DTA) techniques, which indicate that the material does not decompose before melting. The melting point of grown crystal was observed as 180 °C by melting point apparatus. The NLO property was confirmed by the powder technique of Kurtz and Perry. The dielectric behaviour of the sample was also studied for the first time.

  6. Ketones and Human Performance.

    PubMed

    Scott, Jonathan M; Deuster, Patricia A

    Everyone is seeking nutritional strategies that might benefit performance. One approach receiving much attention is ketones, or ketosis. Ketones are very simple compounds made of hydrogen, carbon, and oxygen, and ketosis is a metabolic state whereby the body uses predominantly ketones. Ketosis can be achieved by fasting for longer than 72 hours or by following a very lowcarbohydrate, high-fat diet (ketogenic diet) for several days to weeks. Alternatively, ketone supplements purportedly induce ketosis rapidly and do not require strict adherence to any specific type of diet; however, much of the touted benefits are anecdotal. A potential role for ketosis as a performance enhancer was first introduced in 1983 with the idea that chronic ketosis without caloric restriction could preserve submaximal exercise capability by sparing glycogen or conserving the limited carbohydrate stores. Few human studies on the effects of a ketogenic diet on performance have yielded positive results, and most studies have yielded equivocal or null results, and a few negative results. Many questions about ketones relevant to Special Operations Forces (SOF) remain unanswered. At present, a ketogenic diet and/or a ketone supplement do not appear confer performance benefits for SOF. Instead, Operators should engage with their unit dietitian to develop individualized nutritional strategies based on unique mission requirements. The authors review the concept of a ketogenic diet, describe some potential benefits and risks of ketosis, review the performance literature and how to measure ketone status, and then summarize the landscape in 2017. 2017.

  7. Precise side-chain conformation analysis of L-phenylalanine in α-helical polypeptide by quantum-chemical calculation and 13C CP-MAS NMR measurement

    NASA Astrophysics Data System (ADS)

    Niimura, Subaru; Suzuki, Junya; Kurosu, Hiromichi; Yamanobe, Takeshi; Shoji, Akira

    2010-04-01

    To clarify the positive role of side-chain conformation in the stability of protein secondary structure (main-chain conformation), we successfully calculated the optimization structure of a well-defined α-helical octadecapeptide composed of L-alanine (Ala) and L-phenylalanine (Phe) residues, H-(Ala) 8-Phe-(Ala) 9-OH, based on the molecular orbital calculation with density functional theory (DFT/B3LYP/6-31G(d)). From the total energy and the precise secondary structural parameters such as main-chain dihedral angles and hydrogen-bond parameters of the optimized structure, we confirmed that the conformational stability of an α-helix is affected dominantly by the side-chain conformation ( χ1) of the Phe residue in this system: model A ( T form: around 180° of χ1) is most stable in α-helix and model B ( G + form: around -60° of χ1) is next stable, but model C ( G - form: around 60° of χ1) is less stable. In addition, we demonstrate that the stable conformation of poly( L-phenylalanine) is an α-helix with the side-chain T form, by comparison of the carbonyl 13C chemical shift measured by 13C CP-MAS NMR and the calculated one.

  8. Chiral zinc phenylalanine nanofibers with fluorescence.

    PubMed

    Chen, Erdan; Guo, Beidou; Zhang, Baohong; Gan, Li-Hua; Gong, Jian Ru

    2011-09-01

    Chiral Zn(II)/D-,L-phenylalanine (Phe) bio-coordination polymer nanofibers with fluorescence were prepared by fast coordination-assisted assembly. The synthetic strategy is based on the fact that the Zn2+ ions were linked to oxygen atoms from carboxylate groups of the D- or L-amino acid by coordination interactions to form the chiral polymers. The Zn(II)/D-,L-Phe nanofibers had homogeneous diameters in the range of 700-900 nm and ultra-long length in several hundred micrometers, and the surface of the fiber was extremely smooth. In addition, the enantiomers of Zn(II)/Phe nanofibers exhibited both optical activity and fluorescent property in the solid state, which has great potential for application in the field of biomimetic nanofabrication and micro-/nano-optoelectronics.

  9. Phenylalanine and Phenylglycine Analogues as Arginine Mimetics in Dengue Protease Inhibitors.

    PubMed

    Weigel, Lena F; Nitsche, Christoph; Graf, Dominik; Bartenschlager, Ralf; Klein, Christian D

    2015-10-08

    Dengue virus is an increasingly global pathogen. One of the promising targets for antiviral drug discovery against dengue and related flaviviruses such as West Nile virus is the viral serine protease NS2B-NS3. We here report the synthesis and in vitro characterization of potent peptidic inhibitors of dengue virus protease that incorporate phenylalanine and phenylglycine derivatives as arginine-mimicking groups with modulated basicity. The most promising compounds were (4-amidino)-L-phenylalanine-containing inhibitors, which reached nanomolar affinities against dengue virus protease. The type and position of the substituents on the phenylglycine and phenylalanine side chains has a significant effect on the inhibitory activity against dengue virus protease and selectivity against other proteases. In addition, the non-natural, basic amino acids described here may have relevance for the development of other peptidic and peptidomimetic drugs such as inhibitors of the blood clotting cascade.

  10. 21 CFR 862.1555 - Phenylalanine test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... measure free phenylalanine (an amino acid) in serum, plasma, and urine. Measurements of phenylalanine are... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Phenylalanine test system. 862.1555 Section 862.1555 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED...

  11. 21 CFR 862.1555 - Phenylalanine test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... measure free phenylalanine (an amino acid) in serum, plasma, and urine. Measurements of phenylalanine are... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Phenylalanine test system. 862.1555 Section 862.1555 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED...

  12. N-Benzoyl-D-phenylalanine attenuates brain acetylcholinesterase in neonatal streptozotocin-diabetic rats.

    PubMed

    Ashokkumar, Natarajan; Pari, Leelavinothan; Ramkumar, Kunga Mohan

    2006-09-01

    The effect of hyperglycaemia due to experimental diabetes in male Wistar rats causes a decrease in the level of acetylcholinesterase (AChE) with significant increase in lipid peroxidative markers: thiobarbituric acid-reactive substances (TBARS) and hydroperoxides in brains of experimental animals. The decreased activity of both salt soluble and detergent soluble acetylcholinesterase observed in diabetes may be attributed to lack of insulin which causes specific alterations in the level of neurotransmitter, thus causing brain dysfunction. Administration of non-sulfonylurea drug N-benzoyl-D-phenylalanine (NBDP) could protect against direct action of lipid peroxidation on brain AChE and in this way it might be useful in the prevention of cholinergic neural dysfunction, which is one of the major complications in diabetes.

  13. Inborn errors of ketogenesis and ketone body utilization.

    PubMed

    Sass, Jörn Oliver

    2012-01-01

    Ketone bodies acetoacetate and 3-hydroxy-n-butyric acid are metabolites derived from fatty acids and ketogenic amino acids such as leucine. They are mainly produced in the liver via reactions catalyzed by the ketogenic enzymes mitochondrial 3-hydroxy-3-methylglutary-coenzyme A synthase and 3-hydroxy-3-methylglutary-coenzyme A lyase. After prolonged starvation, ketone bodies can provide up to two-thirds of the brain's energy requirements. The rate-limiting enzyme of ketone body utilization (ketolysis) is succinyl-coenzyme A:3-oxoacid coenzyme A transferase. The subsequent step of ketolysis is catalyzed by 2-methylactoacetyl-coenzyme A thiolase, which is also involved in isoleucine catabolism. Inborn errors of metabolism affecting those four enzymes are presented and discussed in the context of differential diagnoses. While disorders of ketogenesis can present with hypoketotic hypoglycemia, inborn errors of ketolysis are characterized by metabolic decompensations with ketoacidosis. If those diseases are considered early and appropriate treatment is initiated without delay, patients with inborn errors of ketone body metabolism often have a good clinical outcome.

  14. Growth and characterization of an efficient new NLO single crystal L-phenylalanine D-methionine for frequency conversion and optoelectronic applications

    NASA Astrophysics Data System (ADS)

    Sangeetha, P.; Jayaprakash, P.; Nageshwari, M.; Rathika Thaya Kumari, C.; Sudha, S.; Prakash, M.; Vinitha, G.; Lydia Caroline, M.

    2017-11-01

    Optically active single crystals of L-phenylalanine D-methionine (LPDM) were grown by slow evaporation technique by co-crystallization of amino acids L-phenylalanine and D-methionine in water. The unit cell dimensions have been identified from single crystal X-ray diffraction technique. The existences of various hydrocarbyls were examined by FTIR and FT-Raman spectroscopy. The carbon and hydrogen environment of the grown crystals were analyzed by FT NMR spectrum. The optical absorption studies show that the crystal is transparent in the visible region with a lower cut-off wavelength of 259 nm and there by optical band gap energy Eg is calculated to be 5.35 eV. The Urbach energy, extinction coefficient, reflectance were calculated from UV-absorption data. Further, the thermal stability and accurate melting point has been investigated by TG/DSC techniques. The Kurtz powder SHG was confirmed using Nd:YAG laser with fundamental wavelength of 1064 nm. The dielectric behavior of the specimen has been determined for various temperatures (313 K, 333 K, 353 K, 373 K) at different frequencies. Fluorescence study and the time resolved decay calculation was also performed for the LPDM crystal. Optical nonlinear susceptibility was measured in LPDM and the real and imaginary part of χ3 was evaluated by Z-scan technique using open and closed apertures.

  15. Infrared Spectra of the 1-CHLOROMETHYL-1-METHYLALLYL and 1-CHLOROMETHYL-2-METHYLALLYL Radicals Isolated in Solid Para-Hydrogen

    NASA Astrophysics Data System (ADS)

    Amicangelo, Jay C.; Lee, Yuan-Pern

    2017-06-01

    The reaction of chlorine atoms (Cl) with isoprene (C_5H_8) in solid para-hydrogen (p-H_2) matrices at 3.2 K has been studied using infrared spectroscopy. Mixtures of C_5H_8 and Cl_2 were co-deposited in p-H_2 at 3.2 K, followed by irradiation at 365 nm to cause the photodissociation of Cl_2 and the subsequent reaction of Cl atoms with C_5H_8. Upon 365 nm photolysis, a series of new lines appeared in the infrared spectrum, with the strongest appearing at 807.8 and 796.7 \\wn. To determine the grouping of lines to distinct chemical species, secondary photolysis was performed using a low-pressure Hg lamp in combination with various filters. Based on the secondary photolysis behavior, it was determined that the majority of the new lines belong to two distinct chemical species, designated as set A (3047.2, 1482.2, 1459.5, 1396.6, 1349.6, 1268.2, 1237.9, 1170.3, 1108.8, 807.8, 754.1, 605.6, 526.9, 472.7 \\wn) and set B (3112.7, 1487.6, 1382.6, 1257.7, 1229.1, 1034.8, 975.8, 942.4, 796.7, 667.9, 569.7 \\wn). The most likely reactions to occur between Cl and C_5H_8 under the low temperature conditions in solid p-H_2 are the addition of the Cl atom to the four distinct alkene carbon atoms to produce the corresponding chlorine atom addition radicals (ClC_5H_8). Quantum-chemical calculations were performed at the B3PW91/6-311++G(2d,2p) level of theory for the four possible ClC_5H_8 radicals in order to determine the relative energetics and the predicted harmonic vibrational spectra for each radical. The calculations predict that the addition of Cl to each of the four carbons is exothermic, with relative energies of 0.0, 74.5, 67.4, and 7.9 kJ/mol for the addition to carbons 1 - 4, respectively. When the lines of set A and B are compared to the scaled harmonic vibrational spectra for all four of the possible Cl addition radicals, it is found that the best agreement for set A is with the radical produced by the addition to carbon 4 (1-chloromethyl-2-methylallyl radical) and the

  16. Vibrational spectra, optical properties, NBO and HOMO-LUMO analysis of L-Phenylalanine L-Phenylalaninium Perchlorate: DFT calculations.

    PubMed

    Elleuch, Nabil; Ben Ahmed, Ali; Feki, Habib; Abid, Younes; Minot, Christian

    2014-01-01

    In this work, we report a combined experimental and theoretical study of a nonlinear optical material, L-Phenylalanine L-Phenylalaninium Perchlorate. Single crystals of the title compound have been grown by slow evaporation of an aqueous solution at room temperature. Theoretical calculations were preceded by redetermination of the crystal X-ray structure. The compound crystallizes in the non-centro symmetric space group P2(1)2(1)2(1) of the orthorhombic system. The FT-IR and Raman spectra of the crystal were recorded and analyzed. The density functional theory (DFT) computations have been performed at B3LYP/6-31G(d) level to derive equilibrium geometry, vibrational wavenumbers, intensity and NLO properties. All observed vibrational bands have been discussed and assigned to normal mode or to combinations on the basis of our DFT calculations as a primary source of attribution and also by comparison with the previous results for similar compounds. Natural bond orbital analysis was carried out to demonstrate the various inter-and intramolecular interaction that are responsible of the stabilization of the compound. The lowering of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy gap appears to be the cause of its enhanced charge transfer interaction leading to high NLO activity. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Structure-activity relationships of N-beta-phenylpropionyl-L-tyrosine and its derivatives on the inhibition of an identifiable giant neurone of an African giant snail (Achatina fulica Férussac).

    PubMed Central

    Ariyoshi, Y.; Takeuchi, H.

    1982-01-01

    1 Inhibitory effects of N-beta-phenylpropionyl-L-tyrosine, N-beta-phenylpropionyl-L-tryptophan and their derivatives on an identifiable giant neurone, TAN (tonically autoactive neurone) of an African giant snail (Achatina fulica Férussac) were examined in an attempt to elucidate which structural features are necessary to produce the effect. 2 Of the compounds examined, N-beta-cyclohexylpropionyl-L-tyrosine showed the strongest effect. Its critical concentration (c.c.) was 3 X 10(-8)-10(-7)M, about ten times lower than that of N-beta-phenylpropionyl-L-tyrosine (c.c., 3 X 10(-7)-10(-6)M). N-beta-cyclohexylpropionyl-L-tryptophan (c.c., 10(-6)M) had an effect almost similar to that of N-beta-phenylpropionyl-L-tryptophan (c.c., 10(-6)M). 3 N-beta-Phenylpropionyl-N-methyl-L-tyrosine had no effect at a high concentration. 4 Effects of N-beta-phenylpropionyl-L-tyrosine amide (c.c., 3 X 10(-7)-10(-6)M) and N-beta-phenylpropionyl-L-tryptophan amide (c.c., 10(-6)M) were very similar to those of N-beta-phenylpropionyl-L-tyrosine and N-beta-phenylpropionyl-L-tryptophan respectively. 5 N-beta-Phenylpropionyl-p-amino-L-phenylalanine (c.c., 3 X 10(-5)-10(-4)M) and N-beta-phenylpropionyl-p-chloro-L-phenylalanine (c.c., 10(-4)M) had only a weak effect. 6 It is proposed that the structural features producing the effect are as follows: the active compound has a phenyl or a cyclohexyl group (hydrophobic binding group), after a suitable distance a peptide bond (proton donor and proton acceptor), adjacently a carbonyl group (proton acceptor), and a phenolic hydroxyl or an indolyl imino group (proton donor) in the molecule. PMID:7150871

  18. The contribution of ketone bodies to basal and activity-dependent neuronal oxidation in vivo

    PubMed Central

    Chowdhury, Golam MI; Jiang, Lihong; Rothman, Douglas L; Behar, Kevin L

    2014-01-01

    The capacity of ketone bodies to replace glucose in support of neuronal function is unresolved. Here, we determined the contributions of glucose and ketone bodies to neocortical oxidative metabolism over a large range of brain activity in rats fasted 36 hours and infused intravenously with [2,4-13C2]-D-β-hydroxybutyrate (BHB). Three animal groups and conditions were studied: awake ex vivo, pentobarbital-induced isoelectricity ex vivo, and halothane-anesthetized in vivo, the latter data reanalyzed from a recent study. Rates of neuronal acetyl-CoA oxidation from ketone bodies (VacCoA-kbN) and pyruvate (VpdhN), and the glutamate-glutamine cycle (Vcyc) were determined by metabolic modeling of 13C label trapped in major brain amino acid pools. VacCoA-kbN increased gradually with increasing activity, as compared with the steeper change in tricarboxylic acid (TCA) cycle rate (VtcaN), supporting a decreasing percentage of neuronal ketone oxidation: ∼100% (isoelectricity), 56% (halothane anesthesia), 36% (awake) with the BHB plasma levels achieved in our experiments (6 to 13 mM). In awake animals ketone oxidation reached saturation for blood levels >17 mM, accounting for 62% of neuronal substrate oxidation, the remainder (38%) provided by glucose. We conclude that ketone bodies present at sufficient concentration to saturate metabolism provides full support of basal (housekeeping) energy needs and up to approximately half of the activity-dependent oxidative needs of neurons. PMID:24780902

  19. The contribution of ketone bodies to basal and activity-dependent neuronal oxidation in vivo.

    PubMed

    Chowdhury, Golam M I; Jiang, Lihong; Rothman, Douglas L; Behar, Kevin L

    2014-07-01

    The capacity of ketone bodies to replace glucose in support of neuronal function is unresolved. Here, we determined the contributions of glucose and ketone bodies to neocortical oxidative metabolism over a large range of brain activity in rats fasted 36 hours and infused intravenously with [2,4-(13)C₂]-D-β-hydroxybutyrate (BHB). Three animal groups and conditions were studied: awake ex vivo, pentobarbital-induced isoelectricity ex vivo, and halothane-anesthetized in vivo, the latter data reanalyzed from a recent study. Rates of neuronal acetyl-CoA oxidation from ketone bodies (V(acCoA-kbN)) and pyruvate (V(pdhN)), and the glutamate-glutamine cycle (V(cyc)) were determined by metabolic modeling of (13)C label trapped in major brain amino acid pools. V(acCoA-kbN) increased gradually with increasing activity, as compared with the steeper change in tricarboxylic acid (TCA) cycle rate (V(tcaN)), supporting a decreasing percentage of neuronal ketone oxidation: ∼100% (isoelectricity), 56% (halothane anesthesia), 36% (awake) with the BHB plasma levels achieved in our experiments (6 to 13 mM). In awake animals ketone oxidation reached saturation for blood levels >17 mM, accounting for 62% of neuronal substrate oxidation, the remainder (38%) provided by glucose. We conclude that ketone bodies present at sufficient concentration to saturate metabolism provides full support of basal (housekeeping) energy needs and up to approximately half of the activity-dependent oxidative needs of neurons.

  20. Clinical review: Ketones and brain injury

    PubMed Central

    2011-01-01

    Although much feared by clinicians, the ability to produce ketones has allowed humans to withstand prolonged periods of starvation. At such times, ketones can supply up to 50% of basal energy requirements. More interesting, however, is the fact that ketones can provide as much as 70% of the brain's energy needs, more efficiently than glucose. Studies suggest that during times of acute brain injury, cerebral uptake of ketones increases significantly. Researchers have thus attempted to attenuate the effects of cerebral injury by administering ketones exogenously. Hypertonic saline is commonly utilized for management of intracranial hypertension following cerebral injury. A solution containing both hypertonic saline and ketones may prove ideal for managing the dual problems of refractory intracranial hypertension and low cerebral energy levels. The purpose of the present review is to explore the physiology of ketone body utilization by the brain in health and in a variety of neurological conditions, and to discuss the potential for ketone supplementation as a therapeutic option in traumatic brain injury. PMID:21489321

  1. Comparative use of benzhydrylamine and chloromethylated resins in solid-phase synthesis of carboxamide terminal peptides. Synthesis of oxytocin derivatives

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hruby, V.J.; Upson, D.A.; Agarwal, N.S.

    1977-10-28

    Specifically deuterated derivatives of the peptide hormone oxytocin were synthesized by the solid-phase method of peptide synthesis using either the standard chloromethylated resin or the benzhydrylamine resin as the support for the syntheses, and a comparison of the overall efficiency of the syntheses on the two resins was made. (1-Hemi-DL-(..beta..,..beta..-/sup 2/H/sub 2/) cystine) oxytocin was synthesized using the standard chloromethylated resin, and the two diastereomers were separated and purified by partition chromatography and gel filtration in an overall yield of about 30%. (1-Hemi-DL-(..cap alpha..-/sup 2/H/sub 1/) cystine) oxytocin was prepared using the benzhydrylamine resin to prepare the nonapeptide resin precursor,more » but otherwise using essentially identical conditions as used for the synthesis on the chloromethylated resin. Again the two diastereomers were separated and purified by partition chromatography and gel filtration. The overall yield of purified diastereomers under the best conditions was about 49%. For the synthesis of the latter compounds, S-3,4-dimethylbenzyl protecting groups were used to introduce the cysteine residues. The overall yields of the peptide hormone derivatives prepared on the benzhydrylamine resin were substantially improved if HF reactions were run at lower temperatures (0/sup 0/C rather than 25/sup 0/C), and if the S-3,4-dimethylbenzyl rather than the S-benzyl group was used for cysteine protection. Reproducible procedures for preparing benzhydrylamine resins with amino substitution levels of 0.15-0.45 mmol of amino group/g of resin were developed.« less

  2. Pd(OAc)2-Catalyzed Domino Reactions of 1-Chloro-2-Haloarenes and 2-Haloaryl Tosylates with Hindered Grignard Reagents via Palladium Associated Arynes

    PubMed Central

    Dong, Cheng-Guo; Hu, Qiao-Sheng

    2008-01-01

    The palladium associated aryne generation strategy and Pd(OAc)2-catalyzed annulative Domino reactions of 1-chloro-2-halobenzenes and 2-haloaryl tosylates with hindered Grignard reagents via palladium associated arynes are described. The palladium associated aryne generation strategy described here not only allows the high yield, one-step access to potentially useful substituted fluorenes from readily available 1-chloro-2-halobenzenes and 2-haloaryl tosylates, but may also lead to the development of other tandem reactions based on these readily available o-leaving group bearing haloarenes PMID:17048842

  3. Pd(OAc)(2)-catalyzed Domino reactions of 1-chloro-2-haloarenes and 2-haloaryl tosylates with hindered Grignard reagents via palladium-associated arynes.

    PubMed

    Dong, Cheng-Guo; Hu, Qiao-Sheng

    2006-10-26

    The palladium-associated aryne generation strategy and Pd(OAc)(2)-catalyzed annulative Domino reactions of 1-chloro-2-halobenzenes and 2-haloaryl tosylates with hindered Grignard reagents via palladium-associated arynes are described. The palladium-associated aryne generation strategy described here not only allows the high yield, one-step access to potentially useful substituted fluorenes from readily available 1-chloro-2-halobenzenes and 2-haloaryl tosylates, but may also lead to the development of other tandem reactions based on these readily available ortho leaving group bearing haloarenes. [reaction: see text

  4. Fractional reactive extraction for symmetrical separation of 4-nitro-D,L-phenylalanine in centrifugal contactor separators: experiments and modeling.

    PubMed

    Tang, Kewen; Wen, Ping; Zhang, Panliang; Huang, Yan

    2015-01-01

    The enantioselective liquid-liquid extraction of 4-nitro-D,L-phenylalanine (D,L-Nphy) using PdCl2 {(s)-BINAP} as extractant in dichloroethane was studied experimentally in a countercurrent cascade of 10 centrifugal contactor separators (CCSs) at 5°C, involving flow ratio, extractant concentration, and Cl(-) concentration. The steady-state enantiomeric excess (ee) in both stream exits was 90.86% at a 93.29% yield. The predicted value was modeled using an equilibrium stage approach. The correlation between model and experiment was satisfactory. The model was applied to optimize the production of both enantiomers in >97% ee and >99% ee. 14 stages and 16 stages are required for 97% ee and 99% ee for both enantiomers, respectively. © 2014 Wiley Periodicals, Inc.

  5. Efficient palladium-catalyzed asymmetric allylic alkylation of ketones and aldehydes.

    PubMed

    Zhao, Xiaohu; Liu, Delong; Xie, Fang; Liu, Yangang; Zhang, Wanbin

    2011-03-21

    Palladium-catalyzed asymmetric allylic alkylation of ketones, via enamines generated in situ as nucleophiles, were carried out smoothly with chiral metallocene-based P,N-ligands. Under the same conditions, however, reactions of aldehydes could hardly be observed. Subsequently, this obstacle was resolved by using chiral metallocene-based P,P-ligands. Both ketones and aldehydes afforded excellent enantioselectivities with up to 98% ee and 94% ee, respectively.

  6. Zur Biosynthese von Phenylalanin und Tyrosin

    NASA Astrophysics Data System (ADS)

    Lingens, F.; Keller, E.

    1983-03-01

    With the discovery of arogenic acid two new pathways for the biosynthesis of phenylalanine and tyrosine have been revealed. The occurrence of two, three, or four pathways for the biosynthesis of phenylalanine and tyrosine in microorganisms and plants may be a useful tool for taxonomic classifications. Investigations on enterobacteriaceae, pseudomonads, flavobacteria, streptomycetes, archaebacteria, and on Sphaerotilus, Trichococcus and Leptothrix species from bulking sludge are described. The possible role of arogenate in the evolution of the pathways for tyrosine and phenylalanine biosynthesis is discussed.

  7. Trypsin from the processing waste of the lane snapper (Lutjanus synagris) and its compatibility with oxidants, surfactants and commercial detergents.

    PubMed

    Espósito, Talita S; Marcuschi, Marina; Amaral, Ian P G; Carvalho, Luiz B; Bezerra, Ranilson S

    2010-05-26

    A trypsin from the viscera of the lane snapper (Lutjanus synagris) was purified by heat treatment, fractionation with ammonium sulfate and affinity chromatography. The molecular weight of the enzyme was estimated to be 28.4 kDa (SDS-PAGE). The purified enzyme was capable of hydrolyzing the specific substrate for trypsin benzoyl-arginine-p-nitroanilide (BApNA) and was inhibited by benzamidine and tosyl lysine chloromethyl ketone (TLCK), synthetic trypsin inhibitors and phenylmethylsulfonyl fluoride (PMSF), which is a serine-protease inhibitor. The enzyme exhibited maximal activity at pH 9.0 and 45 degrees C and retained 100% of the activity after incubation at the optimal temperature for 30 min. At a concentration of 10 mM, activity was slightly activated by Ca(2+) and inhibited by the following ions in decreasing order: Cd(2+) > Hg(2+) > Cu(2+) > Zn(2+) > Al(3+). The effects of Ba(2+), K(1+) and Li(1+) proved to be less intensive. Using 1% (w/v) azocasein as substrate, the enzyme revealed high resistance (60% residual activity) when incubated with 10% H(2)O(2) for 75 min. The enzyme retained more than 80% activity after 60 min in the presence of different surfactants (Tween 20, Tween 80 and sodium choleate). The alkaline protease demonstrated compatibility with commercial detergents (7 mg/mL), such as Bem-te-vi, Surf and Ala, retaining more than 50% of initial activity after 60 min at 25 degrees C and 30 min at 40 degrees C. The thermostability and compatibility of this enzyme with commercial detergents suggest a good potentiality for application in the detergent industry.

  8. Invasion of Epithelial Cells and Proteolysis of Cellular Focal Adhesion Components by Distinct Types of Porphyromonas gingivalis Fimbriae

    PubMed Central

    Nakagawa, Ichiro; Inaba, Hiroaki; Yamamura, Taihei; Kato, Takahiro; Kawai, Shinji; Ooshima, Takashi; Amano, Atsuo

    2006-01-01

    Porphyromonas gingivalis fimbriae are classified into six types (types I to V and Ib) based on the fimA genes encoding FimA (a subunit of fimbriae), and they play a critical role in bacterial interactions with host tissues. In this study, we compared the efficiencies of P. gingivalis strains with distinct types of fimbriae for invasion of epithelial cells and for degradation of cellular focal adhesion components, paxillin, and focal adhesion kinase (FAK). Six representative strains with the different types of fimbriae were tested, and P. gingivalis with type II fimbriae (type II P. gingivalis) adhered to and invaded epithelial cells at significantly greater levels than the other strains. There were negligible differences in gingipain activities among the six strains; however, type II P. gingivalis apparently degraded intracellular paxillin in association with a loss of phosphorylation 30 min after infection. Degradation was blocked with cytochalasin D or in mutants with fimA disrupted. Paxillin was degraded by the mutant with Lys-gingipain disrupted, and this degradation was prevented by inhibition of Arg-gingipain activity by Nα-p-tosyl-l-lysine chloromethyl ketone. FAK was also degraded by type II P. gingivalis. Cellular focal adhesions with green fluorescent protein-paxillin macroaggregates were clearly destroyed, and this was associated with cellular morphological changes and microtubule disassembly. In an in vitro wound closure assay, type II P. gingivalis significantly inhibited cellular migration and proliferation compared to the cellular migration and proliferation observed with the other types. These results suggest that type II P. gingivalis efficiently invades epithelial cells and degrades focal adhesion components with Arg-gingipain, which results in cellular impairment during wound healing and periodontal tissue regeneration. PMID:16790749

  9. Facile and efficient electrochemical enantiomer recognition of phenylalanine using β-Cyclodextrin immobilized on reduced graphene oxide.

    PubMed

    Zaidi, Shabi Abbas

    2017-08-15

    This work demonstrates the facile and efficient preparation protocol of β-Cyclodextrin-reduced graphene oxide modified glassy carbon electrode (β-CD/RGO/GCE) sensor for an impressive chiral selectivity analysis for phenylalanine enantiomers. In this work, the immobilization of β-CD over graphene sheets allows the excellent enantiomer recognition due to the large surface area and high conductivity of graphene sheets and extraordinary supramolecular (host-guest interaction) property of β-CD. The proposed sensor was well characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and electrochemical impedance spectroscopy (EIS) techniques. The analytical studies demonstrated that the β-CD/RGO/GCE exhibit superior chiral recognition toward L-phenylalanine as compared to D-phenylalanine. Under optimum conditions, the developed sensor displayed a good linear range from 0.4 to 40µM with the limit of detection (LOD) values of 0.10µM and 0.15µM for l- and D-phenylalanine, respectively. Furthermore, the proposed sensor exhibits good stability and regeneration capacity. Thus, the as-synthesized material can be exploited for electrochemical enantiomer recognition successfully. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Regiospecific cytochrome P450-catalyzed nitration of L-tryptophan in thaxtomin phytotoxin biosynthesis

    USDA-ARS?s Scientific Manuscript database

    Thaxtomins, phytotoxins produced by plant pathogenic Streptomyces species, contain a rare nitro group that is essential for phytotoxicity. The N,N'-dimethyldiketopiperazine core of thaxtomins is assembled from L-phenylalanine and L-4-nitrotryptophan by a nonribosomal peptide synthetase. Nitric oxide...

  11. Crystal growth, structural, optical, spectral and thermal studies of tris( L-phenylalanine) L-phenylalaninium nitrate: A new organic nonlinear optical material

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

    Tris( L-phenylalanine) L-phenylalaninium nitrate, C 9H 12NO 2+·NO 3-·3C 9H 11NO 2 (TPLPN), a new organic nonlinear optical material was grown from aqueous solution by slow evaporation solution growth at room temperature. The grown crystals were subjected to powder X-ray diffraction and single crystal X-ray diffraction studies to confirm the crystalline nature and crystal structure. The modes of vibration of different molecular groups present in TPLPN have been identified by FTIR spectral analysis. The presence of hydrogen and carbon in the grown crystal were confirmed by using proton and carbon nuclear magnetic resonance (NMR) spectral analyses. The optical transmission spectral study establishes good transmitting ability of the crystal in the entire visible region. The thermogravimetric (TG) and differential thermal analyses (DTA) were carried out to understand the thermal stability of the sample. The nonlinear optical property of the compound observed using Kurtz powder second harmonic generation test assets the suitability of the grown material for the frequency conversion of laser radiation of Nd:YAG.

  12. Effect of N-benzoyl-d-phenylalanine on lipid profile in liver of neonatal streptozotocin diabetic rats.

    PubMed

    Pari, Leelavinothan; Ashokkumar, Natarajan

    2005-10-01

    The effect of N-benzoyl-d-phenylalanine (NBDP) and metformin combination treatment on liver lipids and lipid peroxidation markers was studied in neonatal streptozotocin (nSTZ) diabetic rats. Oral administration of NBDP (50, 100 and 200 mg/kg body weight) and metformin (500 mg/kg body weight) for 6 weeks significantly reduced the elevated blood glucose, liver cholesterol, triglycerides, free fatty acids and phospholipids. The combination treatment also caused a significant decrease in hepatic hydroxymethyl glutaryl-coenzyme A reductase, Thiobarbituric Acid Reactive Substances (TBARS) and significant increase in reduced glutathione levels. The results show that NBDP and metformin improve the hepatic lipid profile and antioxidant status in nSTZ diabetic rats. Combination treatment was more effective than either drug alone.

  13. Highly enantioselective alpha-aminoxylation of aldehydes and ketones with a polymer-supported organocatalyst.

    PubMed

    Font, Daniel; Bastero, Amaia; Sayalero, Sonia; Jimeno, Ciril; Pericàs, Miquel A

    2007-05-10

    The first catalytic enantioselective alpha-aminoxylation of aldehydes and ketones using an insoluble, polymer-supported organocatalyst (1) derived from trans-4-hydroxyproline is reported (ee: 96-99%). Reaction rates in the aminoxylation of cyclic ketones with 1 are higher than those reported with l-proline. The insoluble nature of 1 simplifies workup conditions and allows catalyst recycling without an apparent decrease in enantioselectivity or yield.

  14. In vivo evaluation and dosimetry of 123I-2-iodo-D-phenylalanine, a new potential tumor-specific tracer for SPECT, in an R1M rhabdomyosarcoma athymic mouse model.

    PubMed

    Kersemans, Veerle; Cornelissen, Bart; Bacher, Klaus; Kersemans, Ken; Thierens, Hubert; Dierckx, Rudi A; De Spiegeleer, Bart; Slegers, Guido; Mertens, John

    2005-12-01

    Earlier reports described the preferential uptake of d-amino acids in tumor-bearing mice. Moreover, it was shown that in tumor cells in vitro the L-amino acid transporter system seemed to lack stereospecificity. Because of the successful results with 123/125I-2-iodo-L-phenylalanine, 123/125I-2-iodo-D-phenylalanine was developed, and its tumor-detecting characteristics were evaluated in vivo. 123I labeling of 2-iodo-D-phenylalanine was performed with a kit formulation by use of Cu1+-assisted nucleophilic exchange. 123I-2-Iodo-D-phenylalanine was evaluated in R1M tumor-bearing athymic mice by dynamic planar imaging (DPI) and dissection. The in vivo stability of the tracer was tested by high-performance liquid chromatography. Tumor tracer retention and tracer contrast were evaluated as a function of time. Two-compartment blood modeling from DPI results and dosimetric calculations from biodistribution results were carried out. Moreover, 125I-2-iodo-D-phenylalanine and 18F-FDG uptake in acute inflammation was investigated. 123I-2-Iodo-D-phenylalanine was metabolically stable. Fast, high, and specific tumor retention was observed. Two-compartment modeling confirmed the fast clearance of the tracer through the kidneys to the bladder, as observed by DPI and dissection. Moreover, compared with the L-isomer, 123I-2-iodo-D-phenylalanine demonstrated faster clearance and faster uptake in the peripheral compartment. No accumulation in the abdomen or in the brain was noted. Dosimetry revealed that 123I-2-iodo-D-phenylalanine demonstrated a low radiation burden comparable to those of 123I-2-iodo-L-phenylalanine and 123I-2-iodo-L-tyrosine. Although 123I-2-iodo-D-phenylalanine showed a tumor retention of only 4%, the tumor contrast was increased up to 350% at 19 h after injection. 123I-2-Iodo-D-phenylalanine is a promising tracer for diagnostic oncologic imaging because of its high, fast, and specific tumor uptake and fast clearance from blood.

  15. Ketone bodies as signaling metabolites

    PubMed Central

    Newman, John C.; Verdin, Eric

    2014-01-01

    Traditionally, the ketone body β-hydroxybutyrate (βOHB) has been looked upon as a carrier of energy from liver to peripheral tissues during fasting or exercise. However, βOHB also signals via extracellular receptors and acts as an endogenous inhibitor of histone deacetylases (HDACs). These recent findings support a model in which βOHB functions to link the environment, in this case the diet, and gene expression via chromatin modifications. Here, we review the regulation and functions of ketone bodies, the relationship between ketone bodies and calorie restriction, and the implications of HDAC inhibition by the ketone body βOHB in the modulation of metabolism, and diseases of aging. PMID:24140022

  16. Laser trapping-induced crystallization of L-phenylalanine through its high-concentration domain formation.

    PubMed

    Yuyama, Ken-ichi; Wu, Chi-Shiun; Sugiyama, Teruki; Masuhara, Hiroshi

    2014-02-01

    We present the laser trapping-induced crystallization of L-phenylalanine through high-concentration domain formation in H2O and D2O solutions which is achieved by focusing a continuous-wave (CW) near-infrared laser beam at the solution surface. Upon laser irradiation into the H2O solution, laser trapping of the liquid-like clusters increases the local concentration, accompanying laser heating, and a single plate-like crystal is eventually prepared at the focal spot. On the other hand, in the D2O solution, a lot of the monohydrate needle-like crystals are observed, not at the focal spot where the concentration is high enough to trigger crystal nucleation, but in the 0.5-1.5 mm range from the focal spot. The dynamics and mechanism of the amazing crystallization behaviour induced by laser trapping are discussed from the viewpoints of the concentration increase due to laser heating depending on solvent, the large high-concentration domain formation by laser trapping of liquid-like clusters, and the orientational disorder of molecules/clusters at the domain edge.

  17. Density functional theory studies on molecular structure and vibrational spectra of NLO crystal L-phenylalanine phenylalanium nitrate for THz application

    NASA Astrophysics Data System (ADS)

    Amalanathan, M.; Hubert Joe, I.; Rastogi, V. K.

    2011-12-01

    Molecular structure, FT-IR and Raman spectra of L-phenylalanine phenylalanium nitrate have been investigated using density functional theory calculation. The polarizability and hyperpolarizability value of the crystal is also calculated. Natural bond orbital analysis confirms the presence of intramolecular charge transfer and the hydrogen bonding interaction. Simultaneous activation of ring C sbnd C stretching modes shows the non-centrosymmetric symmetry. Terahertz time-domain spectroscopy has been used to detect the absorption spectra in the frequency range from 0.05 to 1.3 THz. Theoretically predicted β value exhibits the high nonlinear optical activity.

  18. Role of Hydrogen Bonding on Nonlinear Mechano-Optical Behavior of L-Phenylalanine-based Poly(ester urea)s.

    NASA Astrophysics Data System (ADS)

    Chen, Keke; Yu, Jiayi; Guzman, Gustavo; Es-Haghi, S. Shams; Becker, Matthew L.; Cakmak, Miko

    The uniaxial mechano-optical behavior of a series of amorphous L-phenylalanine-based poly(ester urea) (PEU) films was studied in the rubbery state using a custom real-time measurement system. When the materials were subjected to deformation at temperatures near the glass transition temperature (Tg) , the photoelastic behavior was manifested by a small increase in birefringence with a significant increase in true stress. At temperatures above Tg, PEUs with a shorter diol chain length exhibited a liquid-liquid (Tll) transition at about 1.06 Tg (K), above which the material transforms from a heterogeneous ``liquid of fixed-structure'' to a ``true liquid'' state. The initial photoelastic behavior disappears with increasing temperature, as the initial slope of the stress optical curves becomes temperature independent. Fourier transform infrared spectra of PEUs revealed that the average strength of hydrogen bonding diminishes with increasing temperature. For PEUs with the longest diol chain length, the area associated with N-H stretching region exhibits a linear temperature dependence. The presence of hydrogen bonding enhances the ``stiff'' segmental correlations between adjacent chains in the PEU structure. As a result, the photoelastic constant decreases with increasing hydrogen bonding strength. This work was supported by the Ohio Department of Development's Innovation Platform Program and The National Science Foundation.

  19. Effect of alcohol consumption on the liver detoxication capacity as measured by [13C2]aminopyrine and L-[1-13C]phenylalanine breath tests.

    PubMed

    Wutzke, Klaus D; Wigger, Marianne

    2009-09-01

    The aim of this study was to investigate the hepatic microsomal and cytosolic functions by using the 13CO2 breath test in healthy subjects either before or after consumption of red wine. Twelve adults received [13C2]aminopyrine and L-[1-13C]phenylalanine together with a standardised dinner. Expired air samples were taken over 6 h. After a wash-out period, the subjects consumed 0.4 ml ethanol per kg per day together with dinner over a 7.5-day period on average. Thereafter, 13C-tracer administration was repeated under identical conditions. The 13CO2 enrichments were measured by isotope ratio mass spectrometry. The mean cumulative percentage 13C-dose recovery after administration of [13C2]aminopyrine and L-[1-13C]phenylalanine either without or with red wine consumption amounted to 17.0+/-4.4 vs. 14.7+/-3.1% (p=0.170) and 14.0+/-2.8 vs. 11.5+/-3.9% (p=0.084), respectively. Moderate alcohol consumption does not induce significant short-term changes of the microsomal and the cytosolic function of the human liver in healthy subjects.

  20. Crystal Structure of a Novel N-Substituted L-Amino Acid Dioxygenase from Burkholderia ambifaria AMMD

    PubMed Central

    Qin, Hui-Min; Miyakawa, Takuya; Jia, Min Ze; Nakamura, Akira; Ohtsuka, Jun; Xue, You-Lin; Kawashima, Takashi; Kasahara, Takuya; Hibi, Makoto; Ogawa, Jun; Tanokura, Masaru

    2013-01-01

    A novel dioxygenase from Burkholderia ambifaria AMMD (SadA) stereoselectively catalyzes the C3-hydroxylation of N-substituted branched-chain or aromatic L-amino acids, especially N-succinyl-L-leucine, coupled with the conversion of α-ketoglutarate to succinate and CO2. To elucidate the structural basis of the substrate specificity and stereoselective hydroxylation, we determined the crystal structures of the SadA.Zn(II) and SadA.Zn(II).α-KG complexes at 1.77 Å and 1.98 Å resolutions, respectively. SadA adopted a double-stranded β-helix fold at the core of the structure. In addition, an HXD/EXnH motif in the active site coordinated a Zn(II) as a substitute for Fe(II). The α-KG molecule also coordinated Zn(II) in a bidentate manner via its 1-carboxylate and 2-oxo groups. Based on the SadA.Zn(II).α-KG structure and mutation analyses, we constructed substrate-binding models with N-succinyl-L-leucine and N-succinyl-L-phenylalanine, which provided new insight into the substrate specificity. The results will be useful for the rational design of SadA variants aimed at the recognition of various N-succinyl L-amino acids. PMID:23724013

  1. Reliable radiosynthesis of 4-[10B]borono-2-[18F]fluoro-L-phenylalanine with quality assurance for boron neutron capture therapy-oriented diagnosis.

    PubMed

    Ishiwata, Kiichi; Ebinuma, Ryoichi; Watanabe, Chuichi; Hayashi, Kunpei; Toyohara, Jun

    2018-06-05

    The aim of this study was to establish a reliable and routine method for the preparation of 4-[ 10 B]borono-2-[ 18 F]fluoro-L-phenylalanine (L-[ 18 F]FBPA) for boron neutron capture therapy-oriented diagnosis using positron emission tomography. To produce L-[ 18 F]FBPA by electrophilic fluorination of 4-[ 10 B]borono-L-phenylalanine (L-BPA) with [ 18 F]acetylhypofluorite ([ 18 F]AcOF) via [ 18 F]F 2 derived from the 20 Ne(d,α) 18 F nuclear reaction, several preparation parameters and characteristics of L-[ 18 F]FBPA were investigated, including: pre-irradiation for [ 18 F]F 2 production, the carrier F 2 content in the Ne target, L-BPA-to-F 2 ratios, separation with high-performance liquid chromatography (HPLC) using 10 different eluents, enantiomeric purity, and residual trifluoroacetic acid used as the reaction solvent by gas chromatography-mass spectrometry. The activity yields and molar activities of L-[ 18 F]FBPA (n = 38) were 1200 ± 160 MBq and 46-113 GBq/mmol, respectively, after deuteron-irradiation for 2 h. Two 5 min pre-irradiations prior to [ 18 F]F 2 production for 18 F-labeling were preferable. For L-[ 18 F]FBPA synthesis, 0.15-0.2% of carrier F 2 in Ne and L-BPA-to-F 2 ratios > 2 were preferable. HPLC separations with five of the 10 eluents provided injectable L-[ 18 F]FBPA without any further formulation processing, which resulted in a synthesis time of 32 min. Among the five eluents, 1 mM phosphate-buffered saline was the eluent of choice. The L-[ 18 F]FBPA injection was sterile and pyrogen-free, and contained very small amounts of D-enantiomer (< 0.1% of L-[ 18 F]FBPA), L-BPA (< 1% of L-FBPA), and trifluoroacetic acid (< 0.5 ppm). L-[ 18 F]FBPA injection was reliably prepared by the electrophilic fluorination of L-BPA with [ 18 F]AcOF followed by HPLC separation with 1 mM phosphate-buffered saline.

  2. γ-Sultam-cored N,N-ligands in the ruthenium(ii)-catalyzed asymmetric transfer hydrogenation of aryl ketones.

    PubMed

    Rast, Slavko; Modec, Barbara; Stephan, Michel; Mohar, Barbara

    2016-02-14

    The synthesis of new enantiopure syn- and anti-3-(α-aminobenzyl)-benzo-γ-sultam ligands 6 and their application in the ruthenium(ii)-catalyzed asymmetric transfer hydrogenation (ATH) of ketones using formic acid/triethylamine is described. In particular, benzo-fused cyclic ketones afforded excellent enantioselectivities in reasonable time employing a low loading of the syn ligand-containing catalyst. A never-before-seen dynamic kinetic resolution (DKR) during reduction of a γ-keto carboxylic ester (S7) derivative of 1-indanone is realized leading as well to excellent induction.

  3. Ketone body metabolism and cardiovascular disease

    PubMed Central

    Cotter, David G.; Schugar, Rebecca C.

    2013-01-01

    Ketone bodies are metabolized through evolutionarily conserved pathways that support bioenergetic homeostasis, particularly in brain, heart, and skeletal muscle when carbohydrates are in short supply. The metabolism of ketone bodies interfaces with the tricarboxylic acid cycle, β-oxidation of fatty acids, de novo lipogenesis, sterol biosynthesis, glucose metabolism, the mitochondrial electron transport chain, hormonal signaling, intracellular signal transduction pathways, and the microbiome. Here we review the mechanisms through which ketone bodies are metabolized and how their signals are transmitted. We focus on the roles this metabolic pathway may play in cardiovascular disease states, the bioenergetic benefits of myocardial ketone body oxidation, and prospective interactions among ketone body metabolism, obesity, metabolic syndrome, and atherosclerosis. Ketone body metabolism is noninvasively quantifiable in humans and is responsive to nutritional interventions. Therefore, further investigation of this pathway in disease models and in humans may ultimately yield tailored diagnostic strategies and therapies for specific pathological states. PMID:23396451

  4. Real-time terahertz wave imaging by nonlinear optical frequency up-conversion in a 4-dimethylamino-N'-methyl-4'-stilbazolium tosylate crystal

    NASA Astrophysics Data System (ADS)

    Fan, Shuzhen; Qi, Feng; Notake, Takashi; Nawata, Kouji; Matsukawa, Takeshi; Takida, Yuma; Minamide, Hiroaki

    2014-03-01

    Real-time terahertz (THz) wave imaging has wide applications in areas such as security, industry, biology, medicine, pharmacy, and arts. In this letter, we report on real-time room-temperature THz imaging by nonlinear optical frequency up-conversion in organic 4-dimethylamino-N'-methyl-4'-stilbazolium tosylate crystal. The active projection-imaging system consisted of (1) THz wave generation, (2) THz-near-infrared hybrid optics, (3) THz wave up-conversion, and (4) an InGaAs camera working at 60 frames per second. The pumping laser system consisted of two optical parametric oscillators pumped by a nano-second frequency-doubled Nd:YAG laser. THz-wave images of handmade samples at 19.3 THz were taken, and videos of a sample moving and a ruler stuck with a black polyethylene film moving were supplied online to show real-time ability. Thanks to the high speed and high responsivity of this technology, real-time THz imaging with a higher signal-to-noise ratio than a commercially available THz micro-bolometer camera was proven to be feasible. By changing the phase-matching condition, i.e., by changing the wavelength of the pumping laser, we suggest THz imaging with a narrow THz frequency band of interest in a wide range from approximately 2 to 30 THz is possible.

  5. Interferon-alpha therapy in patients with hepatitis C virus infection increases plasma phenylalanine and the phenylalanine to tyrosine ratio.

    PubMed

    Zoller, Heinz; Schloegl, Anna; Schroecksnadel, Sebastian; Vogel, Wolfgang; Fuchs, Dietmar

    2012-05-01

    Higher blood levels of the essential amino acid phenylalanine (Phe) together with impaired conversion of Phe to tyrosine (Tyr) have been observed in patients suffering from inflammatory conditions. Data suggest that inflammatory responses may interfere with Phe metabolism. This study aimed to investigate whether treatment with cytokine interferon-α (IFN-α) influences Phe concentrations and the Phe to Tyr ratios (Phe/Tyr) measured by HPLC. Twenty-five patients (9 females, 16 males, aged mean ± SD: 44.5 ± 11.0 years) with hepatitis C virus (HCV) infection were examined before and after 1 month of effective antiviral therapy with pegylated IFN-α and weight-based ribavirin. Results were compared to HCV-RNA titers and concentrations of neopterin. IFN-α treatment was associated with a drop of HCV load (from median 6.3 to 3.2 log10 copies/μL; P<0.001) and an increase of neopterin concentrations (from median 4.83 to 12.1 nM; P=0.001) which confirms effectiveness of therapy. Before therapy, median Phe concentration were 123.9 μM, Tyr was 98.8 μM, and Phe/Tyr was 1.23 μmol/μmol, and under therapy median Phe concentrations increased to 132.6 μM and Phe/Tyr to 1.33 (both P<0.05; paired rank test), Tyr levels remained unchanged. The increase of Phe concentrations and of Phe/Tyr in HCV infected individuals is caused by IFN-α therapy. Data indicate that activity of enzyme phenylalanine 4-hydroxylase becomes impaired. Future studies should show whether side effects of IFN-α treatment such as mood changes and depression will be associated with the alterations of Phe metabolism.

  6. Raspberry Ketone Protects Rats Fed High-Fat Diets Against Nonalcoholic Steatohepatitis

    PubMed Central

    Wang, Lili; Zhang, Fengqing

    2012-01-01

    Abstract The protective effect of raspberry ketone against nonalcoholic steatohepatitis (NASH) was tested by using a high-fat diet-induced NASH model, and its mechanism was explored. Forty Sprague–Dawley rats with a 1:1 male to female ratio were randomly divided into five groups: the normal control (NC) group (n=8) fed normal diet for 8 weeks, the model control (MC) group (n=8) fed high-fat diet (82% standard diet, 8.3% yolk powder, 9.0% lard, 0.5% cholesterol, and 0.2% sodium taurocholate), and the raspberry ketone low-dose (0.5%) (RKL) group (n=8), the raspberry ketone middle-dose (1%) (RKM) group (n=8), and the raspberry ketone high-dose (2%) (RKH) group (n=8) fed high-fat diet for 4 weeks. After 8 weeks of experiment, all the rats were sacrificed, and blood lipid parameters (total cholesterol [TC], triglycerides [TG], high-density lipoprotein cholesterol [HDL-C], and low-density lipoprotein cholesterol [LDL-C]), liver function parameters (serum alanine aminotransferase [ALT], aspartate aminotransferase [AST], and alkaline phosphatase [ALP]), leptin (LEP), free fatty acid (FFA), tumor necrosis factor α (TNF-α), blood glucose (GLU), and insulin (INS) with calculated INS resistance index (IRI) and INS-sensitive index (ISI) were measured in rats. Therefore, we determined the peroxisome proliferator-activated receptor (PPAR)-α activity in liver homogenate and the levels of low-density lipoprotein receptor (LDLR), high-sensitivity C-reactive protein (hs-CRP), adiponection (APN), superoxide dismutase, and malondialdehyde (MDA). The liver tissues of rats in each group were imaged by electron microscopy with hematoxylin–eosin as the staining agent. The levels of TG, TC, LDL-C, ALT, AST, ALP, GLU, INS, IRI, FFA, LEP, TNF-α, MDA, and hs-CRP of MC rats were significantly increased (P<.05, P<.01). Therefore, the levels of HDL-C, ISI, PPAR-α, LDLR, and APN were significantly decreased (P<.05, P<.01). Compared with the MC group, each parameter in the RKL, RKM, and

  7. Raspberry ketone protects rats fed high-fat diets against nonalcoholic steatohepatitis.

    PubMed

    Wang, Lili; Meng, Xianjun; Zhang, Fengqing

    2012-05-01

    The protective effect of raspberry ketone against nonalcoholic steatohepatitis (NASH) was tested by using a high-fat diet-induced NASH model, and its mechanism was explored. Forty Sprague-Dawley rats with a 1:1 male to female ratio were randomly divided into five groups: the normal control (NC) group (n=8) fed normal diet for 8 weeks, the model control (MC) group (n=8) fed high-fat diet (82% standard diet, 8.3% yolk powder, 9.0% lard, 0.5% cholesterol, and 0.2% sodium taurocholate), and the raspberry ketone low-dose (0.5%) (RKL) group (n=8), the raspberry ketone middle-dose (1%) (RKM) group (n=8), and the raspberry ketone high-dose (2%) (RKH) group (n=8) fed high-fat diet for 4 weeks. After 8 weeks of experiment, all the rats were sacrificed, and blood lipid parameters (total cholesterol [TC], triglycerides [TG], high-density lipoprotein cholesterol [HDL-C], and low-density lipoprotein cholesterol [LDL-C]), liver function parameters (serum alanine aminotransferase [ALT], aspartate aminotransferase [AST], and alkaline phosphatase [ALP]), leptin (LEP), free fatty acid (FFA), tumor necrosis factor α (TNF-α), blood glucose (GLU), and insulin (INS) with calculated INS resistance index (IRI) and INS-sensitive index (ISI) were measured in rats. Therefore, we determined the peroxisome proliferator-activated receptor (PPAR)-α activity in liver homogenate and the levels of low-density lipoprotein receptor (LDLR), high-sensitivity C-reactive protein (hs-CRP), adiponection (APN), superoxide dismutase, and malondialdehyde (MDA). The liver tissues of rats in each group were imaged by electron microscopy with hematoxylin-eosin as the staining agent. The levels of TG, TC, LDL-C, ALT, AST, ALP, GLU, INS, IRI, FFA, LEP, TNF-α, MDA, and hs-CRP of MC rats were significantly increased (P<.05, P<.01). Therefore, the levels of HDL-C, ISI, PPAR-α, LDLR, and APN were significantly decreased (P<.05, P<.01). Compared with the MC group, each parameter in the RKL, RKM, and RKH groups was

  8. Crystal growth, structural, optical, spectral and thermal studies of tris(L-phenylalanine)L-phenylalaninium nitrate: a new organic nonlinear optical material.

    PubMed

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

    2011-10-15

    Tris(L-phenylalanine)L-phenylalaninium nitrate, C(9)H(12)NO(2)(+)·NO(3)(-)·3C(9)H(11)NO(2) (TPLPN), a new organic nonlinear optical material was grown from aqueous solution by slow evaporation solution growth at room temperature. The grown crystals were subjected to powder X-ray diffraction and single crystal X-ray diffraction studies to confirm the crystalline nature and crystal structure. The modes of vibration of different molecular groups present in TPLPN have been identified by FTIR spectral analysis. The presence of hydrogen and carbon in the grown crystal were confirmed by using proton and carbon nuclear magnetic resonance (NMR) spectral analyses. The optical transmission spectral study establishes good transmitting ability of the crystal in the entire visible region. The thermogravimetric (TG) and differential thermal analyses (DTA) were carried out to understand the thermal stability of the sample. The nonlinear optical property of the compound observed using Kurtz powder second harmonic generation test assets the suitability of the grown material for the frequency conversion of laser radiation of Nd:YAG. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. General Synthesis of Alkenyl Sulfides by Palladium-Catalyzed Thioetherification of Alkenyl Halides and Tosylates.

    PubMed

    Velasco, Noelia; Virumbrales, Cintia; Sanz, Roberto; Suárez-Pantiga, Samuel; Fernández-Rodríguez, Manuel A

    2018-05-08

    The cross-coupling reaction of alkenyl bromides with thiols catalyzed by palladium complexes derived from inexpensive dppf ligand is reported. These reactions occur under low catalyst loading and in high yields and display wide scope, including the coupling of bulky thiols and trisubstituted bromoolefins, and functional group tolerance. In addition, the thioetherification of less reactive chloroalkenes and, for the first time, alkenyl tosylates was accomplished using a catalyst generated from CyPF tBu alkylbisphosphine ligand.

  10. Structure-activity relationships among substituted N-benzoyl derivatives of phenylalanine and its analogs in a microbial antitumor prescreen I: Derivatives of o-fluoro-DL-phenylalanine.

    PubMed

    Otani, T T; Briley, M R

    1982-02-01

    Twelve derivatives of 0-fluoro-dl-phenylalanine containing fluorine, chlorine, methoxy, and nitro radicals in various positions of the aromatic ring of the benzoyl group were prepared and tested in a Lactobacillus casei system. It was found that most substitutions in the benzoyl phenyl ring resulted in a compound exhibiting greater growth-inhibiting activity than the nonsubstituted benzoyl-o-fluorophenylalanine. The greatest activity was observed in the ortho-substituted fluoro compound and the meta- and para-substituted chloro and nitro compounds. With the methoxy group, the position of substitution appeared unimportant, since all three methoxy isomers exhibited essentially equal inhibition. Nitro substitution in the ortho position had a protective effect in that the product was less active than the unsubstituted benzoyl-o-fluoro-dl-phenylalanine.

  11. A Ketone Ester Drink Increases Postexercise Muscle Glycogen Synthesis in Humans.

    PubMed

    Holdsworth, David A; Cox, Peter J; Kirk, Tom; Stradling, Huw; Impey, Samuel G; Clarke, Kieran

    2017-09-01

    Physical endurance can be limited by muscle glycogen stores, in that glycogen depletion markedly reduces external work. During carbohydrate restriction, the liver synthesizes the ketone bodies, D-β-hydroxybutyrate, and acetoacetate from fatty acids. In animals and in the presence of glucose, D-β-hydroxybutyrate promotes insulin secretion and increases glycogen synthesis. Here we determined whether a dietary ketone ester, combined with plentiful glucose, can increase postexercise glycogen synthesis in human skeletal muscle. After an interval-based glycogen depletion exercise protocol, 12 well-trained male athletes completed a randomized, three-arm, blinded crossover recovery study that consisted of consumption of either a taste-matched, zero-calorie control or a ketone monoester drink, followed by a 10-mM glucose clamp or saline infusion for 2 h. The three postexercise conditions were control drink then saline infusion, control drink then hyperglycemic clamp, or ketone ester drink then hyperglycemic clamp. Skeletal muscle glycogen content was determined in muscle biopsies of vastus lateralis taken before and after the 2-h clamps. The ketone ester drink increased blood D-β-hydroxybutyrate concentrations to a maximum of 5.3 versus 0.7 mM for the control drink (P < 0.0001). During the 2-h glucose clamps, insulin levels were twofold higher (31 vs 16 mU·L, P < 0.01) and glucose uptake 32% faster (1.66 vs 1.26 g·kg, P < 0.001). The ketone drink increased by 61 g, the total glucose infused for 2 h, from 197 to 258 g, and muscle glycogen was 50% higher (246 vs 164 mmol glycosyl units per kilogram dry weight, P < 0.05) than after the control drink. In the presence of constant high glucose concentrations, a ketone ester drink increased endogenous insulin levels, glucose uptake, and muscle glycogen synthesis.

  12. Effects of N-[(trans-4-isopropylcyclohexyl)-carbonyl]-D-phenylalanine (A-4166) on insulin and glucagon secretion in isolated perfused rat pancreas.

    PubMed

    Hirose, H; Maruyama, H; Ito, K; Seto, Y; Kido, K; Koyama, K; Dan, K; Saruta, T; Kato, R

    1994-04-01

    N-[(trans-4-isopropylcyclohexyl)-carbonyl]-D-phenylalanine (A-4166) has a structure which differs from those of other known blood glucose-lowering agents including sulfonylureas. It has been shown that oral administration of A-4166 exerts blood glucose-lowering effects in animal in vivo studies. In the present study, we investigated the effects of A-4166 on insulin and glucagon secretion at several glucose concentrations using isolated perfused rat pancreas preparations. Both 3.0 and 30 mumol/l A-4166 significantly stimulated insulin secretion as compared with basal levels at glucose concentrations of 8.0 and 11.0 mmol (p < 0.01 and p < 0.05, respectively). In contrast, glucagon secretion was not affected by administration of A-4166 up to 30 mumol/l at these glucose concentrations. At a glucose concentration of 5.6 mmol/l, neither 0.3 nor 3.0 mumol/l A-4166 produced significant changes in insulin and glucagon secretion. However, A-4166 at 30 mumol/l significantly stimulated insulin secretion and inhibited glucagon secretion as compared with basal levels (p < 0.01 and p < 0.01, respectively). We conclude that A-4166 at 3.0 and 30 mumol/l directly stimulates insulin secretion but has little effect on glucagon secretion in isolated perfused rat pancreas at glucose concentrations of 8.0 and 11.0 mmol/l. these results, taken together with previously published data, suggest that oral administration of A-4166 could be a useful strategy for stimulating endogenous insulin secretion in non-insulin-dependent diabetic patients.

  13. Metabolic transcription analysis of engineered Escherichia coli strains that overproduce L-phenylalanine

    PubMed Central

    Báez-Viveros, José Luis; Flores, Noemí; Juárez, Katy; Castillo-España, Patricia; Bolivar, Francisco; Gosset, Guillermo

    2007-01-01

    Background The rational design of L-phenylalanine (L-Phe) overproducing microorganisms has been successfully achieved by combining different genetic strategies such as inactivation of the phosphoenolpyruvate: phosphotransferase transport system (PTS) and overexpression of key genes (DAHP synthase, transketolase and chorismate mutase-prephenate dehydratase), reaching yields of 0.33 (g-Phe/g-Glc), which correspond to 60% of theoretical maximum. Although genetic modifications introduced into the cell for the generation of overproducing organisms are specifically targeted to a particular pathway, these can trigger unexpected transcriptional responses of several genes. In the current work, metabolic transcription analysis (MTA) of both L-Phe overproducing and non-engineered strains using Real-Time PCR was performed, allowing the detection of transcriptional responses to PTS deletion and plasmid presence of genes related to central carbon metabolism. This MTA included 86 genes encoding enzymes of glycolysis, gluconeogenesis, pentoses phosphate, tricarboxylic acid cycle, fermentative and aromatic amino acid pathways. In addition, 30 genes encoding regulatory proteins and transporters for aromatic compounds and carbohydrates were also analyzed. Results MTA revealed that a set of genes encoding carbohydrate transporters (galP, mglB), gluconeogenic (ppsA, pckA) and fermentative enzymes (ldhA) were significantly induced, while some others were down-regulated such as ppc, pflB, pta and ackA, as a consequence of PTS inactivation. One of the most relevant findings was the coordinated up-regulation of several genes that are exclusively gluconeogenic (fbp, ppsA, pckA, maeB, sfcA, and glyoxylate shunt) in the best PTS- L-Phe overproducing strain (PB12-ev2). Furthermore, it was noticeable that most of the TCA genes showed a strong up-regulation in the presence of multicopy plasmids by an unknown mechanism. A group of genes exhibited transcriptional responses to both PTS inactivation

  14. Studies on a novel approach for the separation of L-phenylalanine amino acid from fermentation broth using a newly developed charged ultrafiltration membrane. I. Single solute system

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Agarwal, A.K.; Huang, R.Y.M.

    A newly developed thin-film composite (TFC) ultrafiltration membrane made of sulfonated poly(phenylene oxide) (SPPO) was used to establish the feasibility of separating L-phenylalanine from the fermentation broth containing a number of dissolved inorganic and organic solutes as an alternative approach to the currently used complex and uneconomical conventional ion-exchange schemes. It was found that the rejection of inorganic salts in a single component system was highly dependent on the feed solution concentration and varied inversely with it. The pH of the feed solution was found to have a strong effect on the rejection of L-phenylalanine, changing it from - 10more » to 90%. This rejection behavior was identical for the two TFC-SPPO membrane samples which had molecular weight cutoff ratings of 10,000 and 20,000, respectively, although the permeate flux of the latter sample was almost twice that of the former sample. It was found that glucose molecules were not rejected by the membrane. 11 refs., 18 figs., 2 tab.« less

  15. EXTRACTION OF TETRAVALENT PLUTONIUM VALUES WITH METHYL ETHYL KETONE, METHYL ISOBUTYL KETONE ACETOPHENONE OR MENTHONE

    DOEpatents

    Seaborg, G.T.

    1961-08-01

    A process is described for extracting tetravalent plutonium from an aqueous acid solution with methyl ethyl ketone, methyl isobutyl ketone, or acetophenone and with the extraction of either tetravalent or hexavalent plutonium into menthone. (AEC)

  16. Postinjection L-phenylalanine increases basal ganglia contrast in PET scans of 6-18F-DOPA

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Doudet, D.J.; McLellan, C.A.; Aigner, T.G.

    The sensitivity of 18F-DOPA positron emission tomography for imaging presynaptic dopamine systems is limited by the amount of specific-to-nonspecific accumulation of radioactivity in brain. In rhesus monkeys, we have been able to increase this ratio by taking advantage of the lag time between 18F-DOPA injection and the formation of its main metabolite, the amino acid 18F-fluoromethoxydopa, the entrance of which into brain is responsible for most of the brain's nonspecific radioactivity. By infusing an unlabeled amino acid, L-phenylalanine, starting 15 min after 18F-DOPA administration, we preferentially blocked the accumulation of 18F-fluoromethoxydopa by preventing its entrance into brain through competition atmore » the large neutral amino acid transport system of the blood-brain barrier. This method appears as reliable as the original and more sensitive, as demonstrated by the comparison of normal and MPTP-treated animals under both conditions.« less

  17. Effects of Physalis peruviana L on Toxicity and Lung Cancer Induction by Nicotine Derived Nitrosamine Ketone in Rats.

    PubMed

    El-Kenawy, Ayman El-Meghawry; Elshama, Said Said; Osman, Hosam-Eldin Hussein

    2015-01-01

    Nicotine-derived nitrosamine ketone (NNK) is considered a key tobacco smoke carcinogen inducing lung tumors. Physalis peruviana L (harankash) is considered one plant with marked health benefits. This study aimed to evaluate Physalis peruviana L effect on the toxic effect of NNK induced lung cancer in the rats by using pulmonary histopathological, immunohistochemical and DNA flow cytometric analyses. Sixty adult male rats were divided into four groups, each consisting of fifteen animals. The first group received saline, the second received two successive toxic doses of NNK only while the third received two successive toxic doses of NNK with a single daily dose of Physalis peruviana L. The fourth group received a single daily dose of Physalis peruviana L only. Toxic doses of NNK induced hyperplasia and adenocarcinoma in the lung and positive immunoreactivity for Ki-67 and p53 staining with disturbance of the lung DNA content. Administration of Physalis peruviana L with NNK led to a mild pulmonary hyperplasia and weak expression of Ki-67 and p53 with an improvement in the lung DNA content. Physalis peruviana L may protect against NNK induced lung carcinogenesis due to its antioxidant and anti-proliferative effects.

  18. A novel microreactor approach for analysis of ketones and aldehydes in breath.

    PubMed

    Fu, Xiao-An; Li, Mingxiao; Biswas, Souvik; Nantz, Michael H; Higashi, Richard M

    2011-11-21

    We report a fabricated microreactor with thousands of micropillars in channels. Each micropillar surface is chemically functionalized to selectively preconcentrate gaseous ketones and aldehydes of exhaled breath and to enhance ultra-trace, rapid analysis by direct-infusion Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometry (MS). The micropillar reactive coating contains the quaternary ammonium aminooxy salt 2-(aminooxy)ethyl-N,N,N-trimethylammonium iodide (ATM) for capturing trace carbonyl VOCs by means of an oximation reaction. We demonstrate the utility of this approach for detection of C(1) to C(12) aldehydes and ketones in exhaled breath, but the approach is applicable to any gaseous sample.

  19. Thermodynamic characteristics of the interaction between nicotinic acid and phenylalanine in an aqueous buffer solution at 298 K

    NASA Astrophysics Data System (ADS)

    Badelin, V. G.; Tyunina, E. Yu.; Mezhevoi, I. N.; Tarasova, G. N.

    2013-08-01

    The interaction between L-phenylalanine and nicotinic acid is studied by solution calorimetry in an aqueous buffer solution (pH 7.35) at different ratios of the reagents. Experimental data on the enthalpy of dissolution of amino acid in the buffer solution of nicotinic acid at 298.15 K are calculated. The values of thermodynamic parameters for the complexation of L-phenylalanine with nicotinic acid are calculated. It is shown that the formation of a 1: 2 molecular complex is stabilized by the entropy factor due to the dominant role of the dehydration effect of initial reagents.

  20. Chemotactic activity from rabbit peritoneal neutrophils. Lack of identity with N-acetyl-DL-phenylalanine beta-napthyl esterase.

    PubMed

    Tsung, P K; Showell, H J; Kegeles, S W; Becker, E L

    1976-08-12

    The chemotactic and N-acetyl-DL-phenylalanine beta-naphthyl esterase activities of rabbit peritoneal neutrophils are separable from each other by both DEAE cellulose and Sephadex G-100 column chromatography. Partially purified esterase obtained from DEAE-cellulose chromatography had molecular weight of 70 000. However, the partially purified fraction contained chemotactic activities with major activity in molecular weight of 28000 and minor activities in the molecular weights of 45000, 21900, 14500 and 10500. Esterase activity is inhibited by 10(-7) M p-nitrophenylethyl-5-chloropentylphosphonate but chemotactic activity is not.

  1. The immunologic and antioxidant effects of L-phenylalanine on the uterine implantation of mice embryos during early pregnancy.

    PubMed

    Dong, Yulan; Bai, Yongping; Liu, Guanhui; Wang, Zixu; Cao, Jing; Chen, Yaoxing; Yang, Hongliang

    2014-10-01

    L-phenylalanine (L-PHE) is a synthetic precursor of catecholamines. Because it cannot be synthesised by an organism, it must be absorbed from the environment. Despite the wide use of L-PHE, whether L-PHE has a negative impact on embryo implantation and development is poorly understood. This study attempted to determine the roles of L-PHE in embryo implantation and development and in the immune response and antioxidant status of the uterus in early pregnancy mice injected intraperitoneally with 320 mg/kg L-PHE. The embryo number of treated mice decreased by 57.6%, and the size of their embryos was reduced by 2.8% (P⟩0.05) along the long diameter and 11.9% (P⟨0.05) along the short diameter at E9 compared with control mice. In addition, L-PHE significantly suppressed B lymphocyte proliferation. L-PHE increased IL-2 secretion but decreased the IL-4 concentration, thereby up-regulating the ratio of IL-2/IL-4 to 1.37-8.45. An analysis of the oxidant and antioxidant status showed that, compared with the control mice, the level of superoxide dismutase activity decreased by 21.54-39.94% and the glutathione peroxidase activity decreased by 15.27-18.96% among the L-PHE-treated mice at E1-E9. However, the malonaldehyde content increased by 14.29%-90.11% among the L-PHE-treated mice. Therefore, L-PHE impaired embryo implantation by disrupting cytokine-based immunity and oxidative stress in the uterus.

  2. Ortho- and meta-tyrosine formation from phenylalanine in human saliva as a marker of hydroxyl radical generation during betel quid chewing.

    PubMed

    Nair, U J; Nair, J; Friesen, M D; Bartsch, H; Ohshima, H

    1995-05-01

    The habit of betel quid chewing, common in South-East Asia and the South Pacific islands, is causally associated with an increased risk of oral cancer. Reactive oxygen species formed from polyphenolic betel quid ingredients and lime at alkaline pH have been implicated as the agents responsible for DNA and tissue damage. To determine whether hydroxyl radical (HO.) is generated in the human oral cavity during chewing of betel quid, the formation of o- and m-tyrosine from L-phenylalanine was measured. Both o- and m-tyrosine were formed in vitro in the presence of extracts of areca nut and/or catechu, transition metal ions such as Cu2+ and Fe2+ and lime or sodium carbonate (alkaline pH). Omission of any of these ingredients from the reaction mixture significantly reduced the yield of tyrosines. Hydroxyl radical scavengers such as ethanol, D-mannitol and dimethylsulfoxide inhibited the phenylalanine oxidation in a dose-dependent fashion. Five volunteers chewed betel quid consisting of betel leaf, areca nut, catechu and slaked lime (without tobacco). Their saliva, collected after chewing betel quid, contained high concentrations of p-tyrosine, but no appreciable amounts of o- or m-tyrosine. Saliva samples from the same subjects after chewing betel quid to which 20 mg phenylalanine had been added contained o- and m-tyrosine at concentrations ranging from 1010 to 3000 nM and from 1110 to 3140 nM respectively. These levels were significantly higher (P < 0.005) than those of subjects who kept phenylalanine in the oral cavity without betel quid, which ranged from 14 to 70 nM for o-tyrosine and from 10 to 35 nM for m-tyrosine. These studies clearly demonstrate that the HO. radical is formed in the human oral cavity during betel quid chewing and is probably implicated in the genetic damage that has been observed in oral epithelial cells of chewers.

  3. Analysis of hydroxylation and nitration products of D-phenylalanine for in vitro and in vivo radical determination using high-performance liquid chromatography and photodiode array detection.

    PubMed

    Oeckl, Patrick; Ferger, Boris

    2009-05-15

    D-phenylalanine is capable of trapping reactive oxygen species (ROS) and reactive nitrogen species (RNS) by forming three major hydroxylation (o-, m-, p-tyrosine) and two major nitration products (nitrophenylalanine, nitrotyrosine). Here, we show how a method for the analysis of these phenylalanine derivatives was established using isocratic HPLC (Nucleosil120, C18 column) coupled with photodiode array detection and validated for cell-free in vitro and in vivo determination of radical formation. An ideal separation was achieved using a mobile phase consisting of 5% acetonitrile, 50mM KH(2)PO(4), pH 3.0, a column temperature of 35 degrees C and a flow rate of 1.0 mL/min. Limits of detection were in the range of 5-100 nM. Linearity was given within 5 nM-100 microM (correlation coefficient >0.999). Retention times as well as peak heights exhibited a high precision (RSD: phenylalanine for ROS/RNS measurement was demonstrated in a cell-free in vitro assay using peroxynitrite and by analysis of brain samples of mice treated with the dopaminergic neurotoxin 6-hydroxydopamine.

  4. Calcium binding to calmodulin mutants monitored by domain-specific intrinsic phenylalanine and tyrosine fluorescence.

    PubMed Central

    VanScyoc, Wendy S; Sorensen, Brenda R; Rusinova, Elena; Laws, William R; Ross, J B Alexander; Shea, Madeline A

    2002-01-01

    Cooperative calcium binding to the two homologous domains of calmodulin (CaM) induces conformational changes that regulate its association with and activation of numerous cellular target proteins. Calcium binding to the pair of high-affinity sites (III and IV in the C-domain) can be monitored by observing calcium-dependent changes in intrinsic tyrosine fluorescence intensity (lambda(ex)/lambda(em) of 277/320 nm). However, calcium binding to the low-affinity sites (I and II in the N-domain) is more difficult to measure with optical spectroscopy because that domain of CaM does not contain tryptophan or tyrosine. We recently demonstrated that calcium-dependent changes in intrinsic phenylalanine fluorescence (lambda(ex)/lambda(em) of 250/280 nm) of an N-domain fragment of CaM reflect occupancy of sites I and II (VanScyoc, W. S., and M. A. Shea, 2001, Protein Sci. 10:1758-1768). Using steady-state and time-resolved fluorescence methods, we now show that these excitation and emission wavelength pairs for phenylalanine and tyrosine fluorescence can be used to monitor equilibrium calcium titrations of the individual domains in full-length CaM. Calcium-dependent changes in phenylalanine fluorescence specifically indicate ion occupancy of sites I and II in the N-domain because phenylalanine residues in the C-domain are nonemissive. Tyrosine emission from the C-domain does not interfere with phenylalanine fluorescence signals from the N-domain. This is the first demonstration that intrinsic fluorescence may be used to monitor calcium binding to each domain of CaM. In this way, we also evaluated how mutations of two residues (Arg74 and Arg90) located between sites II and III can alter the calcium-binding properties of each of the domains. The mutation R74A caused an increase in the calcium affinity of sites I and II in the N-domain. The mutation R90A caused an increase in calcium affinity of sites III and IV in the C-domain whereas R90G caused an increase in calcium affinity

  5. Effects of dietary leucine and phenylalanine on pancreas development, enzyme activity, and relative gene expression in milk-fed Holstein dairy calves.

    PubMed

    Cao, Y C; Yang, X J; Guo, L; Zheng, C; Wang, D D; Cai, C J; Liu, S M; Yao, J H

    2018-05-01

    This study aimed to investigate the effect of dietary supplementation with leucine and phenylalanine on pancreas development, enzyme activity, and related gene expression in male Holstein calves. Twenty male Holstein calves [1 d of age, 38 ± 3 kg of body weight (BW)] were randomly assigned to 1 of the following 4 treatment groups with 5 calves in each group: control, leucine supplementation (1.435 g/L of milk), phenylalanine supplementation (0.725 g/L of milk), and leucine and phenylalanine (1.435 + 0.725 g/L of milk). The diets were made isonitrogenous with the inclusion of alanine in each respective treatment. The feeding trial lasted for 8 wk, including 1 wk for adaption and 7 wk for the feeding experiment. Leucine tended to increase the concentration of total pancreatic protein (mg/kg of BW). Phenylalanine increased the concentrations of plasma insulin, cholecystokinin, and pancreatic DNA (mg/g) and the expression of trypsin gene but decreased the pancreatic protein:DNA ratio and tended to decrease the pancreas weight (g/kg of BW). No differences were observed in total pancreatic DNA (mg/pancreas and mg/kg of BW), pancreatic protein (mg/pancreas), or activities of α-amylase, trypsin, and lipase. The relative expression levels of the genes encoding α-amylase and lipase did not differ among the 4 groups. The supplementation of both leucine and phenylalanine showed an interaction on the pancreas weight (g and g/kg of BW) and a tendency of an interaction on the pancreatic protein concentration (mg/g of pancreas and mg/kg of BW) and the plasma glucose concentration. Leucine tended to increase the size of the pancreatic cells, whereas phenylalanine tended to increase the number of pancreatic cells. However, neither AA affected the activities of the pancreatic enzymes of the calves. These results indicate that leucine and phenylalanine supplementation in milk-fed Holstein calves differentially affect pancreatic growth and development. Copyright © 2018 American

  6. N-heterocyclic carbene catalyzed regioselective oxo-acyloxylation of alkenes with aromatic aldehydes: a high yield synthesis of α-acyloxy ketones and esters.

    PubMed

    Reddi, Rambabu N; Malekar, Pushpa V; Sudalai, Arumugam

    2013-10-14

    An N-heterocyclic carbene (NHC)-catalyzed reaction of alkenes with aromatic aldehydes providing for a high yield synthesis of α-acyloxy ketones and esters has been described. This unprecedented regioselective oxidative process employs NBS and Et3N in stoichiometric amounts and O2 (1 atm) as an oxidant under ambient conditions in DMSO as a solvent.

  7. Efficient Domino Hydroformylation/Benzoin Condensation: Highly Selective Synthesis of α-Hydroxy Ketones.

    PubMed

    Dong, Kaiwu; Sang, Rui; Soule, Jean-Francois; Bruneau, Christian; Franke, Robert; Jackstell, Ralf; Beller, Matthias

    2015-12-07

    An improved domino hydroformylation/benzoin condensation to give α-hydroxy ketones has been developed. Easily available olefins are smoothly converted into the corresponding α-hydroxy ketones in high yields with excellent regioselectivities. Key to success is the use of a specific catalytic system consisting of a rhodium/phosphine complex and the CO2 adduct of an N-heterocyclic carbene. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. 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.

  9. 40 CFR 721.4568 - Methylpolychloro aliphatic ketone.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Methylpolychloro aliphatic ketone. 721... Substances § 721.4568 Methylpolychloro aliphatic ketone. (a) Chemical substance and significant new uses... ketone (PMN No. P-91-1321) is subject to reporting under this section for the significant new uses...

  10. Rhodium-catalyzed Asymmetric Hydrogenation of α-Dehydroamino Ketones: A General Approach to Chiral α-amino Ketones.

    PubMed

    Gao, Wenchao; Wang, Qingli; Xie, Yun; Lv, Hui; Zhang, Xumu

    2016-01-01

    Rhodium/DuanPhos-catalyzed asymmetric hydrogenation of aliphatic α-dehydroamino ketones has been achieved and afforded chiral α-amino ketones in high yields and excellent enantioselectives (up to 99 % ee), which could be reduced further to chiral β-amino alcohols by LiAlH(tBuO)3 with good yields. This protocol provides a readily accessible route for the synthesis of chiral α-amino ketones and chiral β-amino alcohols. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Growth, structural, spectral, optical, and thermal studies on amino acid based new NLO single crystal: L-phenylalanine-4-nitrophenol.

    PubMed

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

    2013-05-01

    A new organic nonlinear optical single crystal, L-phenylalanine-4-nitrophenol (LPAPN) belonging to the amino acid group has been successfully grown by slow evaporation technique. The lattice parameters of the grown crystal have been determined by X-ray diffraction studies. FT-IR spectrum was recorded to identify the presence of functional group and molecular structure was confirmed by NMR spectrum. Thermal strength of the grown crystal has been studied using TG-DTA analyses. The grown crystals were found to be transparent in the entire visible region. The existence of second harmonic generation signals was observed using Nd:YAG laser with fundamental wavelength of 1064 nm. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Study of the antibacterial and antifungal activities of synthetic benzyl bromides, ketones, and corresponding chalcone derivatives.

    PubMed

    Shakhatreh, Muhamad Ali K; Al-Smadi, Mousa L; Khabour, Omar F; Shuaibu, Fatima A; Hussein, Emad I; Alzoubi, Karem H

    2016-01-01

    Several applications of chalcones and their derivatives encouraged researchers to increase their synthesis as an alternative for the treatment of pathogenic bacterial and fungal infections. In the present study, chalcone derivatives were synthesized through cross aldol condensation reaction between 4-( N , N -dimethylamino)benzaldehyde and multiarm aromatic ketones. The multiarm aromatic ketones were synthesized through nucleophilic substitution reaction between 4-hydroxy acetophenone and benzyl bromides. The benzyl bromides, multiarm aromatic ketones, and corresponding chalcone derivatives were evaluated for their activities against eleven clinical pathogenic Gram-positive, Gram-negative bacteria, and three pathogenic fungi by the disk diffusion method. The minimum inhibitory concentration was determined by the microbroth dilution technique. The results of the present study demonstrated that benzyl bromide derivatives have strong antibacterial and antifungal properties as compared to synthetic chalcone derivatives and ketones. Benzyl bromides (1a and 1c) showed high ester activity against Gram-positive bacteria and fungi but moderate activity against Gram-negative bacteria. Therefore, these compounds may be considered as good antibacterial and antifungal drug discovery. However, substituted ketones (2a-b) as well as chalcone derivatives (3a-c) showed no activity against all the tested strains except for ketone (2c), which showed moderate activity against Candida albicans .

  13. Study of the antibacterial and antifungal activities of synthetic benzyl bromides, ketones, and corresponding chalcone derivatives

    PubMed Central

    Shakhatreh, Muhamad Ali K; Al-Smadi, Mousa L; Khabour, Omar F; Shuaibu, Fatima A; Hussein, Emad I; Alzoubi, Karem H

    2016-01-01

    Several applications of chalcones and their derivatives encouraged researchers to increase their synthesis as an alternative for the treatment of pathogenic bacterial and fungal infections. In the present study, chalcone derivatives were synthesized through cross aldol condensation reaction between 4-(N,N-dimethylamino)benzaldehyde and multiarm aromatic ketones. The multiarm aromatic ketones were synthesized through nucleophilic substitution reaction between 4-hydroxy acetophenone and benzyl bromides. The benzyl bromides, multiarm aromatic ketones, and corresponding chalcone derivatives were evaluated for their activities against eleven clinical pathogenic Gram-positive, Gram-negative bacteria, and three pathogenic fungi by the disk diffusion method. The minimum inhibitory concentration was determined by the microbroth dilution technique. The results of the present study demonstrated that benzyl bromide derivatives have strong antibacterial and antifungal properties as compared to synthetic chalcone derivatives and ketones. Benzyl bromides (1a and 1c) showed high ester activity against Gram-positive bacteria and fungi but moderate activity against Gram-negative bacteria. Therefore, these compounds may be considered as good antibacterial and antifungal drug discovery. However, substituted ketones (2a–b) as well as chalcone derivatives (3a–c) showed no activity against all the tested strains except for ketone (2c), which showed moderate activity against Candida albicans. PMID:27877017

  14. L-Phenylalanine concentration in blood of phenylketonuria patients: a modified enzyme colorimetric assay compared with amino acid analysis, tandem mass spectrometry, and HPLC methods.

    PubMed

    De Silva, Veronica; Oldham, Charlie D; May, Sheldon W

    2010-09-01

    Phenylketonuria (PKU) is an autosomal recessive disorder caused by an impaired conversion of L-phenylalanine (Phe) to L-tyrosine, typically resulting from a deficiency in activity of a hepatic and renal enzyme L-phenylalanine hydroxylase. The disease is characterized by an increased concentration of Phe and its metabolites in body fluids. A modified assay based on an enzymatic-colorimetric methodology was developed for measuring blood Phe levels in PKU patients; this method is designed for use with undeproteinized samples and avoids the use of solvents or amphiphilic agents. Thus, the method could be suitable for incorporation into a simple home-monitoring device. We report here on a comparison of blood Phe concentrations in PKU patients measured in undeproteinized plasma using this enzyme colorimetric assay (ECA), with values determined by amino acid analysis (AAA) of deproteinized samples, and HPLC and tandem mass spectrometry (MS/MS) analyses of dried blood spot (DBS) eluates. Pearson correlation coefficients of 0.951, 0.976 and 0.988 were obtained when AAA-measured Phe concentrations were compared with the ECA-, HPLC- or MS/MS-measured values, respectively. A Bland-Altman analysis revealed that mean Phe concentrations determined using AAA were on average 65 μmol/L lower than values measured by our ECA. These results may be the result of minimizing the manipulations performed on the patient sample compared with AAA, HPLC, and MS/MS methods, which involve plasma deproteinization or DBS elution and derivatization. The results reported here confirm that Phe concentrations determined by our ECA method are comparable to those determined by other widely used methods for a broad range of plasma Phe concentrations.

  15. High anion gap metabolic acidosis induced by cumulation of ketones, L- and D-lactate, 5-oxoproline and acute renal failure.

    PubMed

    Heireman, Laura; Mahieu, Boris; Helbert, Mark; Uyttenbroeck, Wim; Stroobants, Jan; Piqueur, Marian

    2017-07-27

    Frequent causes of high anion gap metabolic acidosis (HAGMA) are lactic acidosis, ketoacidosis and impaired renal function. In this case report, a HAGMA caused by ketones, L- and D-lactate, acute renal failure as well as 5-oxoproline is discussed. A 69-year-old woman was admitted to the emergency department with lowered consciousness, hyperventilation, diarrhoea and vomiting. The patient had suffered uncontrolled type 2 diabetes mellitus, underwent gastric bypass surgery in the past and was chronically treated with high doses of paracetamol and fosfomycin. Urosepsis was diagnosed, whilst laboratory analysis of serum bicarbonate concentration and calculation of the anion gap indicated a  HAGMA. L-lactate, D-lactate, β-hydroxybutyric acid, acetone and 5-oxoproline serum levels were markedly elevated and renal function was impaired. We concluded that this case of HAGMA was induced by a variety of underlying conditions: sepsis, hyperglycaemia, prior gastric bypass surgery, decreased renal perfusion and paracetamol intake. Risk factors for 5-oxoproline intoxication present in this case are female gender, sepsis, impaired renal function and uncontrolled type 2 diabetes mellitus. Furthermore, chronic antibiotic treatment with fosfomycin might have played a role in the increased production of 5-oxoproline. Paracetamol-induced 5-oxoproline intoxication should be considered as a cause of HAGMA in patients with female gender, sepsis, impaired renal function or uncontrolled type 2 diabetes mellitus, even when other more obvious causes of HAGMA such as lactate, ketones or renal failure can be identified.

  16. N-triflylthiophosphoramide catalyzed enantioselective Mukaiyama aldol reaction of aldehydes with silyl enol ethers of ketones.

    PubMed

    Cheon, Cheol Hong; Yamamoto, Hisashi

    2010-06-04

    The first Brønsted acid catalyzed asymmetric Mukaiyama aldol reaction of aldehydes using silyl enol ethers of ketones as nucleophiles has been reported. A variety of aldehydes and silyl enol ethers of ketones afforded the aldol products in excellent yields and good to excellent enantioselectivities. Mechanistic studies revealed that the actual catalyst may be changed from the silylated Brønsted acid to the Brønsted acid itself depending on the reaction temperature.

  17. Organocatalytic C-H bond arylation of aldehydes to bis-heteroaryl ketones.

    PubMed

    Toh, Qiao Yan; McNally, Andrew; Vera, Silvia; Erdmann, Nico; Gaunt, Matthew J

    2013-03-13

    An organocatalytic aldehyde C-H bond arylation process for the synthesis of complex heteroaryl ketones has been developed. By exploiting the inherent electrophilicity of diaryliodonium salts, we have found that a commercial N-heterocyclic carbene catalyst promotes the union of heteroaryl aldehydes and these heteroaromatic electrophile equivalents in good yields. This straightforward catalytic protocol offers access to ketones bearing a diverse array of arene and heteroarene substituents that can subsequently be converted into molecules displaying structural motifs commonly found in medicinal agents.

  18. Cerebral Ketone Metabolism During Development and Injury

    PubMed Central

    Prins, Mayumi L.

    2011-01-01

    Cerebral metabolism of ketones is a normal part of the process of brain development. While the mature brain relies on glucose as a primary fuel source, metabolism of ketone bodies remains an alternative energy source under conditions of starvation. The neuroprotective properties of brain ketone metabolism make this alternative substrate a viable therapeutic option for various pathologies. Since the ability to revert to utilizing ketones as an alternative substrate is greatest in the younger post-weaned brain, this particular therapeutic approach remains an untapped resource particularly for pediatric pathological conditions. PMID:22104087

  19. A modified Girard derivatizing reagent for universal profiling and trace analysis of aldehydes and ketones by electrospray ionization tandem mass spectrometry.

    PubMed

    Johnson, David W

    2007-01-01

    4-Hydrazino-N,N,N-trimethyl-4-oxobutanaminium iodide (HTMOB) is a modified Girard derivatizing reagent synthesized to improve the sensitivity of analysis of aldehydes and ketones with electrospray ionization tandem mass spectrometry. Compared with Girard T reagent the measured signal intensity increase is between 3.3 times (succinylacetone) and 7.0 times (17-hydroxyprogesterone). HTMOB is a universal profiling reagent for aldehydes and ketones. A neutral loss of 59 Da scan detects all aldehydes and ketones from acetone to corticosteroids. Applications described include the profiling of ketones, ketoacids and ketodiacids in the urine of children with ketosis and the profiling of long-chain aldehydes incorporated in plasma plasmalogens. Copyright (c) 2007 John Wiley & Sons, Ltd.

  20. Metabolism of D-phenylalanine and its effects on concentrations of brain monoamines and amino acids in rats--a basic study on possibility of clinical use of D-phenylalanine as an antidepressant.

    PubMed

    Hashimoto, H; Nakajima, T; Nishimura, T; Kudo, Y; Takeda, Y; Nakao, M; Kanaya, H; Horiguchi, Y

    1983-01-01

    The effect of D-phenylalanine on the concentrations of brain catecholamines, serotonin, beta-phenylethylamine and amino acids was examined using rats injected intraperitoneally with 200 mg/kg of D-phenylalanine. The contents of these monoamines in the rat brain were not affected by the administration of D-phenylalanine. No spectacular change was observed in the concentrations of brain amino acids except phenylalanine, which increased about four times during 30-60 minutes after the injection. This increase was attributed to the administered D-phenylalanine. To confirm the finding that D-phenylalanine did not affect the content of beta-phenylethylamine, the metabolism of D-phenylalanine was examined using D-[14C]-phenylalanine. It was proven that D-phenylalanine did not convert to beta-phenylethylamine. On the basis of these findings the antidepressant effect of D-phenylalanine was critically discussed.

  1. Solvation Effect on Complexation of Alkali Metal Cations by a Calix[4]arene Ketone Derivative.

    PubMed

    Požar, Josip; Nikšić-Franjić, Ivana; Cvetnić, Marija; Leko, Katarina; Cindro, Nikola; Pičuljan, Katarina; Borilović, Ivana; Frkanec, Leo; Tomišić, Vladislav

    2017-09-14

    The medium effect on the complexation of alkali metal cations with a calix[4]arene ketone derivative (L) was systematically examined in methanol, ethanol, N-methylformamide, N,N-dimethylformamide, dimethyl sulfoxide, and acetonitrile. In all solvents the binding of Na + cation by L was rather efficient, whereas the complexation of other alkali metal cations was observed only in methanol and acetonitrile. Complexation reactions were enthalpically controlled, while ligand dissolution was endothermic in all cases. A notable influence of the solvent on NaL + complex stability could be mainly attributed to the differences in complexation entropies. The higher NaL + stability in comparison to complexes with other alkali metal cations in acetonitrile was predominantly due to a more favorable complexation enthalpy. The 1 H NMR investigations revealed a relatively low affinity of the calixarene sodium complex for inclusion of the solvent molecule in the calixarene hydrophobic cavity, with the exception of acetonitrile. Differences in complex stabilities in the explored solvents, apart from N,N-dimethylformamide and acetonitrile, could be mostly explained by taking into account solely the cation and complex solvation. A considerable solvent effect on the complexation equilibria was proven to be due to an interesting interplay between the transfer enthalpies and entropies of the reactants and the complexes formed.

  2. Effect of sucrose, erythrose-4-phosphate and phenylalanine on biomassa and flavonoid content of callus culture from leaves of Gynura procumbens Merr.

    NASA Astrophysics Data System (ADS)

    Nurisa, Aryana; Kristanti, Alfinda Novi; Manuhara, Yosephine Sri Wulan

    2017-08-01

    The aims of this study were to know the effect of concentration of sucrose, erythrose-4-phosphate and phenylalanine on biomass and flavonoid content of callus cultures from leaves of sambung nyawa (Gynura procumbens Merr.). This study was experimental research with complete randomized design. Callus induction was treated in MS medium supplemented with NAA 2 mg/L, BAP 1 mg/L and sucrose concentration (10 g/L, 30 g/L and 50 g/L) respectively were combined with erythrose-4-phosphate (0 µM, 2,5 µM and 5 µM) and phenylalanine (0 mg/L, 2 mg/L and 3 mg/L), each treatment were repeated four times. After six weeks of culture, fresh and dry weight of calli were measured and extracted with ethanol absolut. Crude extract ethanolic of callus was analyzed used by a modified colorimetric with spectrophotometer method. The best yield of calli biomass (0,672 ± 0,112 gram of fresh weight and 0,033 ± 0,009 gram of dry weight) was obtained in treatment of 30 g/L sucrose of and 5 µM erythrose-4-phosphate. The highest total flavonoid content was obtained of calli treated with 30 g/L of sucrose and 3 mg/L of phenylalanine (3633,4 ppm quercetin/gram dry weight and 15777,8 ppm kaempferol/gram dry weight).

  3. Alterations in Taxol production in plant cell culture via manipulation of the phenylalanine ammonia lyase pathway.

    PubMed

    Brincat, Michelle C; Gibson, Donna M; Shuler, Michael L

    2002-01-01

    One approach to increasing secondary metabolite production in plant cell culture is to manipulate metabolic pathways to utilize more resources toward production of one desired compound or class of compounds, such as diverting carbon flux from competing secondary pathways. Since phenylalanine provides both the phenylisoserine side chain and the benzoyl moiety at C-2 of Taxol, we speculated that blockage of the phenylpropanoid pathway might divert phenylalanine into Taxol biosynthesis. We used specific enzyme inhibitors to target the first enzyme in the phenylpropanoid pathway, phenylalanine ammonia lyase (PAL), the critical control point for conversion of L-phenylalanine to trans-cinnamic acid. Cinnamic acid acted quickly in reducing PAL activity by 40-50%, without affecting total protein levels, but it generally inhibited the taxane pathway, reducing Taxol by 90% of control levels. Of the taxanes produced, 13-acetyl-9-dihydro-baccatin III and 9-dihydrobaccatin III doubled as a percentage of total taxanes in C93AD and CO93P cells treated with 0.20 and 0.25 mM cinnamic acid, when all other taxanes were lowered. The PAL inhibitor alpha-aminooxyacetic acid (AOA) almost entirely shut down Taxol production at both 0.5 and 1.5 mM, whereas L-alpha-aminooxy-beta-phenylpropionic acid (AOPP) had the opposite effect, slightly enhancing Taxol production at 1 microM but having no effect at 10 microM. The discrepancy in the effectiveness of AOA and AOPP and the lack of effect with addition of phenylalanine or benzoic acid derivatives further indicates that the impact of cinnamic acid on Taxol is related not to its effect on PAL but rather to a specific effect on the taxane pathway. On the basis of these results, a less direct route for inhibiting the phenylpropanoid pathway may be required to avoid unwanted side effects and potentially enhance Taxol production.

  4. N-Triflylthiophosphoramide Catalyzed Enantioselective Mukaiyama Aldol Reaction of Aldehydes with Silyl Enol Ethers of Ketones

    PubMed Central

    Cheon, Cheol Hong; Yamamoto, Hisashi

    2010-01-01

    The first Brønsted acid catalyzed asymmetric Mukaiyama aldol reaction of aldehydes using silyl enol ethers of ketones as nucleophiles has been reported. A variety of aldehydes and silyl enol ethers of ketones afforded the aldol products in excellent yields and good to excellent enantioselectivities. Mechanistic studies revealed that the actual catalyst may be changed from the silylated Brønsted acid to Brønsted acid itself depending on the reaction temperature. PMID:20465277

  5. Identity of SMCT1 (SLC5A8) as a neuron-specific Na+-coupled transporter for active uptake of L-lactate and ketone bodies in the brain.

    PubMed

    Martin, Pamela M; Gopal, Elangovan; Ananth, Sudha; Zhuang, Lina; Itagaki, Shiro; Prasad, Balakrishna M; Smith, Sylvia B; Prasad, Puttur D; Ganapathy, Vadivel

    2006-07-01

    SMCT1 is a sodium-coupled (Na(+)-coupled) transporter for l-lactate and short-chain fatty acids. Here, we show that the ketone bodies, beta-d-hydroxybutyrate and acetoacetate, and the branched-chain ketoacid, alpha-ketoisocaproate, are also substrates for the transporter. The transport of these compounds via human SMCT1 is Na(+)-coupled and electrogenic. The Michaelis constant is 1.4 +/- 0.1 mm for beta-d-hydroxybutyrate, 0.21 +/- 0.04 mm for acetoacetate and 0.21 +/- 0.03 mm for alpha-ketoisocaproate. The Na(+) : substrate stoichiometry is 2 : 1. As l-lactate and ketone bodies constitute primary energy substrates for neurons, we investigated the expression pattern of this transporter in the brain. In situ hybridization studies demonstrate widespread expression of SMCT1 mRNA in mouse brain. Immunofluorescence analysis shows that SMCT1 protein is expressed exclusively in neurons. SMCT1 protein co-localizes with MCT2, a neuron-specific Na(+)-independent monocarboxylate transporter. In contrast, there was no overlap of signals for SMCT1 and MCT1, the latter being expressed only in non-neuronal cells. We also demonstrate the neuron-specific expression of SMCT1 in mixed cultures of rat cortical neurons and astrocytes. This represents the first report of an Na(+)-coupled transport system for a major group of energy substrates in neurons. These findings suggest that SMCT1 may play a critical role in the entry of l-lactate and ketone bodies into neurons by a process driven by an electrochemical Na(+) gradient and hence, contribute to the maintenance of the energy status and function of neurons.

  6. Modulation of deprivation-induced food intake by D-phenylalanine.

    PubMed

    Bodnar, R J; Butler, P D

    1983-09-01

    D-phenylalanine has been shown to possess opiate-like effects upon pain perception. The present study examined whether it would have similar opiate-like effects upon food intake in deprived rats. The first experiment demonstrated that food intake of rats deprived for 24 h prior to injection was significantly reduced for 2 h following a 250 mg/kg dose of D-phenylalanine. However, intake over a 24 h period following injection was significantly increased following a 125 mg/kg dose of D-phenylalanine. The second experiment revealed that 0.3, 1.0, 3.0 and 10.0 mg/kg doses of naloxone dose-dependently reduced intake for 2 h in deprived rats when paired with a vehicle injection. However, the inhibitory actions of the two lower naloxone doses were significantly attenuated when paired with an injection of a 250 mg/kg dose of D-phenylalanine. These results are discussed in terms of whether D-phenylalanine possesses direct or indirect opiate-like effects upon ingestion.

  7. Volatilization of ketones from water

    USGS Publications Warehouse

    Rathbun, R.E.; Tai, D.Y.

    1982-01-01

    The overall mass-transfer coefficients for the volatilization from water of acetone, 2-butanone, 2-pentanone, 3-pentanone, 4-methyl-2-pentanone, 2-heptanone, and 2-octanone were measured simultaneously with the oxygen-absorption coefficient in a laboratory stirred water bath. The liquid-film and gas-film coefficients of the two-film model were determined for the ketones from the overall coefficients, and both film resistances were important for volatilization of the ketones.The liquid-film coefficients for the ketones varied with the 0.719 power of the molecular-diffusion coefficient, in agreement with the literature. The liquid-film coefficients showed a variable dependence on molecular weight, with the dependence ranging from the −0.263 power for acetone to the −0.378 power for 2-octanone. This is in contrast with the literature where a constant −0.500 power dependence on the molecular weight is assumed.The gas-film coefficients for the ketones showed no dependence on molecular weight, in contrast with the literature where a −0.500 power is assumed.

  8. Ketone bodies as epigenetic modifiers.

    PubMed

    Ruan, Hai-Bin; Crawford, Peter A

    2018-07-01

    Ketone body metabolism is a dynamic and integrated metabolic node in human physiology, whose roles include but extend beyond alternative fuel provision during carbohydrate restriction. Here we discuss the most recent observations suggesting that ketosis coordinates cellular function via epigenomic regulation. Ketosis has been linked to covalent modifications, including lysine acetylation, methylation, and hydroxybutyrylation, to key histones that serve as dynamic regulators of chromatin architecture and gene transcription. Although it remains to be fully established whether these changes to the epigenome are attributable to ketone bodies themselves or other aspects of ketotic states, the regulated genes mediate classical responses to carbohydrate restriction. Direct regulation of gene expression may occur in-vivo via through ketone body-mediated histone modifications during adherence to low-carbohydrate diets, fasting ketosis, exogenous ketone body therapy, and diabetic ketoacidosis. Additional convergent functional genomics, metabolomics, and proteomics studies are required in both animal models and in humans to identify the molecular mechanisms through which ketosis regulates nuclear signaling events in a myriad of conditions relevant to disease, and the contexts in which the benefits of ketosis might outweigh the risks.

  9. Ketone-DNA: a versatile postsynthetic DNA decoration platform.

    PubMed

    Dey, S; Sheppard, T L

    2001-12-13

    [reaction: see text] A general strategy for the functional diversification of DNA oligonucleotides under physiological conditions was developed. We describe the synthesis of DNA molecules bearing ketone ports (ketone-DNA) and the efficient postsynthetic decoration of ketone-DNA with structurally diverse aminooxy compounds.

  10. Adsorption mechanism of physiologically active L-phenylalanine phosphonodipeptide analogues: Comparison of colloidal silver and macroscopic silver substrates

    NASA Astrophysics Data System (ADS)

    Podstawka, E.; Kudelski, A.; Proniewicz, L. M.

    2007-11-01

    Here we present SERS spectra of several L-phenylalanine (Phe) phosphonodipeptides, i.e., L-Phe- L-Ala-PO 3H 2 ( MD1), L-Phe- L-Va L-PO 3H 2 ( MD2), L-Phe-β-Ala-CH(OH)-PO 3H 2 ( MD3), L-Phe- L-Ala-CH(OH)-PO 3H 2 ( MD4), L-Ala-(3,4-dimethoxy)- L-Phe-PO 3H 2 ( MD5), and L-Ala-(3,4-dimethoxy)-(des-CH 2)- L-Phe-PO 3H 2 ( MD6), immobilized on electrochemically roughened silver electrodes. These spectra are analyzed by theoretical calculations using density functional theory (DFT) at the B3LYP level with 6-31++G∗∗ basis set. In addition, these spectra are compared with SERS spectra of these species adsorbed on a colloidal silver surface. We showed that on the macroscopic silver substrate, the Phe aromatic ring of MD3 and MD4 is oriented vertically, while for MD1 it almost "stands up" on this surface. In the other three cases, the Phe ring adopts a tilted orientation in regard to the substrate. We also find that the phosphonate (-PO32-), methyl/methane, or dimethoxy groups of MD1, MD2, MD3, MD5, and MD6 are involved in the interaction of these phosphonodipeptides with the electrochemically roughened surface. This phenomenon is clearly seen for -CH 2-/-CH 3/-OCH 3 moieties as well as for the PO32- group that adsorbs on the macroscopic silver substrates mainly via the P dbnd O fragment. We also showed that MD4 binds to the macroscopic silver substrate through the hydroxyl, amine, and phosphonate groups, while the methylene/methane moieties are remote from this surface. We found that studied phosphonodipeptides often adsorb differently on the macroscopic silver substrate and on the colloidal silver nanoparticles. For example, MD1 adopts an almost vertical orientation on the electrochemically roughened silver substrate and is tilted or close to flat on the silver nanoparticles.

  11. Tritrichomonas foetus Induces Apoptotic Cell Death in Bovine Vaginal Epithelial Cells

    PubMed Central

    Singh, B. N.; Lucas, J. J.; Hayes, G. R.; Kumar, Ish; Beach, D. H.; Frajblat, Marcel; Gilbert, R. O.; Sommer, U.; Costello, C. E.

    2004-01-01

    Tritrichomonas foetus is a serious veterinary pathogen, causing bovine trichomoniasis, a sexually transmitted disease leading to infertility and abortion. T. foetus infects the mucosal surfaces of the reproductive tract. Infection with T. foetus leads to apoptotic cell death of bovine vaginal epithelial cells (BVECs) in culture. An affinity-purified cysteine protease (CP) fraction yielding on sodium dodecyl sulfate-polyacrylamide gel electrophoresis a single band with an apparent molecular mass of 30 kDa (CP30) also induces BVEC apoptosis. Treatment of CP30 with the protease inhibitors TLCK (Nα-p-tosyl-l-lysine chloromethyl ketone) and E-64 [l-trans-epoxysuccinyl-leucylamide-(4-guanido)-butane] greatly reduces induction of BVEC apoptosis. Matrix-assisted laser desorption ionization-time-of-flight MALDI-TOF mass spectrometry analysis of CP30 reveals a single peak with a molecular mass of 23.7 kDa. Mass spectral peptide sequence analysis of proteolytically digested CP30 reveals homologies to a previously reported cDNA clone, CP8 (D. J. Mallinson, J. Livingstone, K. M. Appleton, S. J. Lees, G. H. Coombs, and M. J. North, Microbiology 141:3077-3085, 1995). Induction of apoptosis is highly species specific, since the related human parasite Trichomonas vaginalis and associated purified CPs did not induce BVEC death. Fluorescence microscopy along with the Cell Death Detection ELISAPLUS assay and flow cytometry analyses were used to detect apoptotic nuclear condensation, DNA fragmentation, and changes in plasma membrane asymmetry in host cells undergoing apoptosis in response to T. foetus infection or incubation with CP30. Additionally, the activation of caspase-3 and inhibition of cell death by caspase inhibitors indicates that caspases are involved in BVEC apoptosis. These results imply that apoptosis is involved in the pathogenesis of T. foetus infection in vivo, which may have important implications for therapeutic interference with host cell death that could alter

  12. Preparation of tritium-labeled optical isomers of amino acids by ligand exchange chromatography on polyacrylamide sorbent containing L-phenylalanine groupings

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zolotarev, Yu.A.; Penkina, V.I.; Dostavalov, I.N.

    Tritium-labeled optically active amino acids are obtained by resolving racemates of the corresponding amino acids by chromatography on a chiral polyacrylamide sorbent, filled with copper ions. The chiral sorbent is obtained by the action of formaldehyde and L-phenylalanine on a Biogel P-4 polyacrylamide gel in an alkaline medium. Data are given on the ligand exchange chromatography of amino acids on this sorbent, depending on the degree of filling of the sorbent by copper ions and the concentration of the eluent. Conditions were selected for the quantitative resolution of racemates of amino acids and examples are given of a preparative obtainingmore » of tritium labeled optical isomers of amino acids.« less

  13. Effects of totally synthetic, low phenylalanine diet on adolescent phenylketonuric patients

    PubMed Central

    McKean, Charles M.

    1971-01-01

    The long-term responses of 5 adolescent phenylketonuric patients to chemically-defined, synthetic diets with normal and low phenylalanine content were determined. The synthetic preparations were found capable of sustaining good health and rapid growth in this group of profoundly retarded, behaviourally disturbed patients over a 3½-year period without clinical or biochemical evidence of nutritional inadequacy. 4 of these patients who were treated for 6 months on a comparable diet, in which 80% of the phenylalanine was replaced by tyrosine, continued to show weight maintenance and height increases. There was no evidence of poor acceptability of the imbalanced diet, whether the blood phenylalanine concentrations were at phenylketonuric or treatment levels. The phenylalanine intake required to maintain blood phenylalanine concentrations of 3-5 mg/100 ml in these 4 patients was well below normal requirements, and ranged between 6·8 and 20·1 mg/kg per day. Predictably, the phenylalanine requirement varied with individual growth rates. All 4 treated patients had objective signs of improved central nervous system function during the six-month period on the phenylalanine-restricted diet. These electrophysiological and behavioural improvements were manifest after blood phenylalanine concentrations fell below 12 mg/100 ml in 3 cases and below 5 mg/100 ml in the fourth. PMID:5118048

  14. Metabolic engineering of the L-phenylalanine pathway in Escherichia coli for the production of S- or R-mandelic acid

    PubMed Central

    2011-01-01

    Background Mandelic acid (MA), an important component in pharmaceutical syntheses, is currently produced exclusively via petrochemical processes. Growing concerns over the environment and fossil energy costs have inspired a quest to develop alternative routes to MA using renewable resources. Herein we report the first direct route to optically pure MA from glucose via genetic modification of the L-phenylalanine pathway in E. coli. Results The introduction of hydroxymandelate synthase (HmaS) from Amycolatopsis orientalis into E. coli led to a yield of 0.092 g/L S-MA. By combined deletion of competing pathways, further optimization of S-MA production was achieved, and the yield reached 0.74 g/L within 24 h. To produce R-MA, hydroxymandelate oxidase (Hmo) from Streptomyces coelicolor and D-mandelate dehydrogenase (DMD) from Rhodotorula graminis were co-expressed in an S-MA-producing strain, and the resulting strain was capable of producing 0.68 g/L R-MA. Finally, phenylpyruvate feeding experiments suggest that HmaS is a potential bottleneck to further improvement in yields. Conclusions We have constructed E. coli strains that successfully accomplished the production of S- and R-MA directly from glucose. Our work provides the first example of the completely fermentative production of S- and R-MA from renewable feedstock. PMID:21910908

  15. Ketone EC50 values in the Microtox test.

    PubMed

    Chen, H F; Hee, S S

    1995-03-01

    The Microtox EC50 values for the following ketones are reported in the following homologous series: straight chain methyl ketones (acetone, 2-butanone, 2-pentanone, 2-hepatonone, 2-octanone, 2-decanone, and 2-tridecanone); methyl ketones substituted at one alpha carbon (3-methyl-2-butanone; 3,3-dimethyl-2-butanone); methyl substituted at two alpha carbons (2,4-dimethyl-3-pentanone; 2,2,4,4-tetramethyl-3-pentanone); phenyl groups replacing methyl in acetone (acetophenone; benzophenone); methyl groups substituted at the alpha carbons of cyclohexanone; and 2,3- 2,4-, and 2,5-hexanediones, most for the first time. While there were linear relationships between log EC50 and MW for the straight chain methyl ketones, and for methyl substitution at the alpha carbon for methyl ketones, there were no other linear relationships. As molecular weight increased, the EC50 values of soluble ketones decreased; as distance between two carbonyl groups decreased so too did EC50 values. Thus, for the ketones the geometry around the carbonyl group is an important determinant of toxicity as well as MW, water solubility, and octanol/water coefficient.

  16. Mating of 2 Laboratory Saccharomyces cerevisiae Strains Resulted in Enhanced Production of 2-Phenylethanol by Biotransformation of L-Phenylalanine.

    PubMed

    Mierzejewska, Jolanta; Tymoszewska, Aleksandra; Chreptowicz, Karolina; Krol, Kamil

    2017-01-01

    2-Phenylethanol (2-PE) is an aromatic alcohol with a rosy scent which is widely used in the food, fragrance, and cosmetic industries. Promising sources of natural 2-PE are microorganisms, especially yeasts, which can produce 2-PE by biosynthesis and biotransformation. Thus, the first challenging goal in the development of biotechnological production of 2-PE is searching for highly productive yeast strains. In the present work, 5 laboratory Saccharomyces cerevisiae strains were tested for the production of 2-PE. Thereafter, 2 of them were hybridized by a mating procedure and, as a result, a new diploid, S. cerevisiae AM1-d, was selected. Within the 72-h batch culture in a medium containing 5 g/L of L-phenylalanine, AM1-d produced 3.83 g/L of 2-PE in a shaking flask. In this way, we managed to select the diploid S. cerevisiae AM1-d strain, showing a 3- and 5-fold increase in 2-PE production in comparison to parental strains. Remarkably, the enhanced production of 2-PE by the hybrid of 2 yeast laboratory strains is demonstrated here for the first time. © 2017 S. Karger AG, Basel.

  17. Studies on the inhibition of Moloney murine leukemia virus reverse transcriptase by N-tritylamino acids and N-tritylamino acid-nucleotide compounds.

    PubMed

    Hawtrey, Arthur; Pieterse, Anton; van Zyl, Johann; Van der Bijl, Pieter; Van der Merwe, Marichen; Nel, William; Ariatti, Mario

    2008-09-01

    N-Acylated derivatives of 8-(6-aminohexyl) amino-adenosine-5 '-phosphate were prepared and studied with regard to their effect on DNA synthesis by the Moloney leukemia virus reverse transcriptase. N-palmitoyl and N-nicotinyl derivatives and bis-8-(6-aminohexyl) amino-5'-AMP inhibited the enzyme partially using poly (rA).oligo d(pT)(16-18) as template-primer with [(3)H]dTTP. In order to increase hydrophobicity in the acyl component tethered to the 8-(6-aminohexyl) amino group on the adenine nucleotide, N-trityl-L-phenylalanine and the N-trityl derivatives of the o, m, and p-fluoro-DL-phenylalanine were initially examined for inhibition of the enzyme using the above template-primer system. The compounds all inhibited the reverse transcriptase with IC(50) values of approximately 60-80 microM. However, when N-trityl-m-fluoro-DL-phenylalanine was coupled to the nucleotide 8-(6-aminohexyl) amino-adenosine-5'-phosphate, the inhibitory activity of this compound increased significantly (IC(50) = 5 microM).

  18. Unlocking the chemotherapeutic potential of beta-aminovinyl ketones and related compounds.

    PubMed

    Gaber, Hatem M; Bagley, Mark C

    2009-07-01

    The role of beta-aminovinyl ketones as synthetic intermediates has been well categorised, but recent developments have shown an interesting array of applications and new chemotherapeutic potential, both in the preparation of biologically active heterocycles and as pharmacophores in their own right.Medicinal chemists are accustomed to using the products of Knoevenagel-type condensations as auxiliaries for the synthesis of N-containing heteroaromatic compounds. One such example of these chemical building blocks are beta-aminovinyl ketones-valuable synthetic intermediates that have been used in the preparation of pyridines, pyrimidines, pyrazoles, and many other heterocyclic motifs. This review highlights their recent use in the synthesis of biologically active targets as part of drug discovery programmes and in natural product synthesis. However, it is becoming increasingly evident that the enaminone motif may serve as a therapeutic pharmacophore in its own right. This review highlights the range of biological responses that beta-aminovinyl ketones elicit, including as antitumour, antibacterial, and anticonvulsant agents. Thus, with a broad spectrum of biological properties and as versatile chemical intermediates, it is clear that beta-aminovinyl ketones offer great potential in the search for new chemotherapeutic agents.

  19. Production of phenylpyruvic acid from L-phenylalanine using an L-amino acid deaminase from Proteus mirabilis: comparison of enzymatic and whole-cell biotransformation approaches.

    PubMed

    Hou, Ying; Hossain, Gazi Sakir; Li, Jianghua; Shin, Hyun-Dong; Liu, Long; Du, Guocheng

    2015-10-01

    Phenylpyruvic acid (PPA) is an important organic acid that has a wide range of applications. In this study, the membrane-bound L-amino acid deaminase (L-AAD) gene from Proteus mirabilis KCTC 2566 was expressed in Escherichia coli BL21(DE3) and then the L-AAD was purified. After that, we used the purified enzyme and the recombinant E. coli whole-cell biocatalyst to produce PPA via a one-step biotransformation from L-phenylalanine. L-AAD was solubilized from the membrane and purified 52-fold with an overall yield of 13 %, which corresponded to a specific activity of 0.94 ± 0.01 μmol PPA min(-1)·mg(-1). Then, the biotransformation conditions for the pure enzyme and the whole-cell biocatalyst were optimized. The maximal production was 2.6 ± 0.1 g·L(-1) (specific activity of 1.02 ± 0.02 μmol PPA min(-1)·mg(-1) protein, 86.7 ± 5 % mass conversion rate, and 1.04 g·L(-1)·h(-1) productivity) and 3.3 ± 0.2 g L(-1) (specific activity of 0.013 ± 0.003 μmol PPA min(-1)·mg(-1) protein, 82.5 ± 4 % mass conversion rate, and 0.55 g·L(-1)·h(-1) productivity) for the pure enzyme and whole-cell biocatalyst, respectively. Comparative studies of the enzymatic and whole-cell biotransformation were performed in terms of specific activity, production, conversion, productivity, stability, need of external cofactors, and recycling. We have developed two eco-friendly and efficient approaches for PPA production. The strategy described herein may aid the biotransformational synthesis of other α-keto acids from their corresponding amino acids.

  20. Antihypertension and anti-cardiovascular remodeling by phenylalanine in spontaneously hypertensive rats: effectiveness and mechanisms.

    PubMed

    Zhao, G; Li, Z; Gu, T

    2001-03-01

    To investigate mechanisms of anti-hypertension and anti-cardiovascular remodeling by phenylalanine (phe) in spontaneously hypertensive rats (SHRs). The comparison of blood pressure (BP) increment with the ages and cardiovascular changes of SHRs was made between the 3% phe-intervented group (SHR-phe) and the control SHRs group. Detection of the structural changes with the VIDAS digital vedio-frequency processing technique and light and electron microscopy were made. The cell growth and proliferation of cultured smooth muscle cells (CSMCs) of the thoracic aortas or myocardial fibroblasts were evaluated by measuring the 3H-thymidine counts per minute (cpm) incorporated into the new synthesized desoxyribonucleic acid (DNA) and determining the cell number with the crystal violet stain technique. The Ca2+ influx was measured in counts/min of 45CaCl2 after incubating it with 5 different concentrations of phenylalanine and the intracellular [Ca2+]i by Fura-II/Am indicator. The total messenger ribonucleic acid (mRNA) of the myocardium was extracted and Northern blot analysis was performed with the probe collagen alpha 2 (I) cDNA. The tyrosine hydroxylase (TH) activity was measured by high-performance liquid chromatography (HPLC) with electrochemical detector after having reacted with its substrate tyrosine and other reagents. The catecholamine contents in brain homogenat were detected by HPLC method. The comparison of pharmacokinetics of phenylalanine among SHR-phe, SHRs and control Wistar Kyoto (WKY) rats was made after intravenous injection of 3H-L-phe (1 ml/kg) by PK-GRAPH Program for kinetic calculation. The 3H-L-phe uptake by CSMCs after incubating for definite intervals was also detected and compared. Phenylalanine could prevent the increase of BP with ages and the heart weight (heart/body weight index). The aortic media thickness and the collagen content in the myocardium were decreased significantly in SHR-phe. Whereas the dearranged cardiovascular structure was

  1. Novel proton exchange membranes based on structure-optimized poly(ether ether ketone ketone)s and nanocrystalline cellulose

    NASA Astrophysics Data System (ADS)

    Ni, Chuangjiang; Wei, Yingcong; Zhao, Qi; Liu, Baijun; Sun, Zhaoyan; Gu, Yan; Zhang, Mingyao; Hu, Wei

    2018-03-01

    Two sulfonated fluorenyl-containing poly(ether ether ketone ketone)s (SFPEEKKs) were synthesized as the matrix of composite proton exchange membranes by directly sulfonating copolymer precursors comprising non-sulfonatable fluorinated segments and sulfonatable fluorenyl-containing segments. Surface-modified nanocrystalline cellulose (NCC) was produced as the "performance-enhancing" filler by treating the microcrystalline cellulose with acid. Two families of SFPEEKK/NCC nanocomposite membranes with various NCC contents were prepared via a solution-casting procedure. Results revealed that the insertion of NCC at a suitable ratio could greatly enhance the proton conductivity of the pristine membranes. For example, the proton conductivity of SFPEEKK-60/NCC-4 (SFPEEKK with 60% fluorenyl segments in the repeating unit, and inserted with 4% NCC) composite membrane was as high as 0.245 S cm-1 at 90 °C, which was 61.2% higher than that of the corresponding pure SFPEEKK-60 membrane. This effect could be attributed to the formation of hydrogen bond networks and proton conduction paths through the interaction between -SO3H/-OH groups on the surface of NCC particles and -SO3H groups on the SFPEEKK backbones. Furthermore, the chemically modified NCC filler and the optimized chemical structure of the SFPEEKK matrix also provided good dimensional stability and mechanical properties of the obtained nanocomposites. In conclusion, these novel nanocomposites can be promising proton exchange membranes for fuel cells at moderate temperatures.

  2. Reactivity of Biliatresone, a Natural Biliary Toxin, with Glutathione, Histamine, and Amino Acids

    PubMed Central

    Koo, Kyung A.; Waisbourd-Zinman, Orith; Wells, Rebecca G.; Pack, Michael; Porter, John R.

    2016-01-01

    In our previous work, we identified a natural toxin, biliatresone, from Dysphania glomulifera and D. littoralis, endemic plants associated with outbreaks of biliary atresia in Australian neonatal livestock. Biliatresone is a very rare isoflavonoid with an α-methylene ketone between two phenyls, 1,2-diaryl-2-propenone, along with methylenedioxy, dimethoxyl, and hydroxyl functional groups, that causes extrahepatic biliary toxicity in zebrafish. The toxic core of biliatresone is a methylene in the α-position relative to the ketone of 1,2-diaryl-2-propenone that serves as an electrophilic Michael acceptor. The α-methylene of biliatresone spontaneously conjugated with water and methanol (MeOH), respectively, via Michael addition in a reverse phase high-performance liquid chromatography (RP-HPLC) analysis. We here report the reactivity of biliatresone toward glutathione (GSH), several amino acids, and other thiol- or imidazole-containing biomolecules. LC-MS and HPLC analysis of the conjugation reaction showed the reactivity of biliatresone to be in the order histidine > N-acetyl-d-cysteine (D-NAC) = N-acetyl-l-cysteine (L-NAC) > histamine > glutathione ≥ cysteine ≫ glycine > glutamate > phenylalanine, while serine and adenine had no reactivity due to intramolecular hydrogen bonding in the protic solvents. The reactivity of ethyl vinyl ketone (EVK, 1-penten-3-one), an example of a highly reactive α,ß-unsaturated ketone, toward GSH gave a 6.7-fold lower reaction rate constant than that of biliatresone. The reaction rate constant of synthetic 1,2-diaryl-2-propen-1-one (DP), a core structure of the toxic molecule, was 10-fold and 1.5-fold weaker in potency compared to the reaction rate constants of biliatresone and EVK, respectively. These results demostrated that the methylenedioxy, dimethoxyl, and hydroxyl functional groups of biliatresone contribute to the stronger reactivity of the Michael acceptor α-methylene ketone toward nucleophiles compared to that of DP

  3. Reactivity of Biliatresone, a Natural Biliary Toxin, with Glutathione, Histamine, and Amino Acids.

    PubMed

    Koo, Kyung A; Waisbourd-Zinman, Orith; Wells, Rebecca G; Pack, Michael; Porter, John R

    2016-02-15

    In our previous work, we identified a natural toxin, biliatresone, from Dysphania glomulifera and D. littoralis, endemic plants associated with outbreaks of biliary atresia in Australian neonatal livestock. Biliatresone is a very rare isoflavonoid with an α-methylene ketone between two phenyls, 1,2-diaryl-2-propenone, along with methylenedioxy, dimethoxyl, and hydroxyl functional groups, that causes extrahepatic biliary toxicity in zebrafish. The toxic core of biliatresone is a methylene in the α-position relative to the ketone of 1,2-diaryl-2-propenone that serves as an electrophilic Michael acceptor. The α-methylene of biliatresone spontaneously conjugated with water and methanol (MeOH), respectively, via Michael addition in a reverse phase high-performance liquid chromatography (RP-HPLC) analysis. We here report the reactivity of biliatresone toward glutathione (GSH), several amino acids, and other thiol- or imidazole-containing biomolecules. LC-MS and HPLC analysis of the conjugation reaction showed the reactivity of biliatresone to be in the order histidine > N-acetyl-d-cysteine (D-NAC) = N-acetyl-l-cysteine (L-NAC) > histamine > glutathione ≥ cysteine ≫ glycine > glutamate > phenylalanine, while serine and adenine had no reactivity due to intramolecular hydrogen bonding in the protic solvents. The reactivity of ethyl vinyl ketone (EVK, 1-penten-3-one), an example of a highly reactive α,ß-unsaturated ketone, toward GSH gave a 6.7-fold lower reaction rate constant than that of biliatresone. The reaction rate constant of synthetic 1,2-diaryl-2-propen-1-one (DP), a core structure of the toxic molecule, was 10-fold and 1.5-fold weaker in potency compared to the reaction rate constants of biliatresone and EVK, respectively. These results demostrated that the methylenedioxy, dimethoxyl, and hydroxyl functional groups of biliatresone contribute to the stronger reactivity of the Michael acceptor α-methylene ketone toward nucleophiles compared to that of DP

  4. Engineering of bacterial methyl ketone synthesis for biofuels.

    PubMed

    Goh, Ee-Been; Baidoo, Edward E K; Keasling, Jay D; Beller, Harry R

    2012-01-01

    We have engineered Escherichia coli to overproduce saturated and monounsaturated aliphatic methyl ketones in the C₁₁ to C₁₅ (diesel) range; this group of methyl ketones includes 2-undecanone and 2-tridecanone, which are of importance to the flavor and fragrance industry and also have favorable cetane numbers (as we report here). We describe specific improvements that resulted in a 700-fold enhancement in methyl ketone titer relative to that of a fatty acid-overproducing E. coli strain, including the following: (i) overproduction of β-ketoacyl coenzyme A (CoA) thioesters achieved by modification of the β-oxidation pathway (specifically, overexpression of a heterologous acyl-CoA oxidase and native FadB and chromosomal deletion of fadA) and (ii) overexpression of a native thioesterase (FadM). FadM was previously associated with oleic acid degradation, not methyl ketone synthesis, but outperformed a recently identified methyl ketone synthase (Solanum habrochaites MKS2 [ShMKS2], a thioesterase from wild tomato) in β-ketoacyl-CoA-overproducing strains tested. Whole-genome transcriptional (microarray) studies led to the discovery that FadM is a valuable catalyst for enhancing methyl ketone production. The use of a two-phase system with decane enhanced methyl ketone production by 4- to 7-fold in addition to increases from genetic modifications.

  5. Modulation of Polymorphonuclear Neutrophil Response to N-formyl-l-methionyl-l-leucyl-l-phenylalanine

    DTIC Science & Technology

    1988-11-10

    mi. Blood drawing was done by a team of ALAAS certified technicians. Previous experience had shown it to be tolerated without evidence of pain or...collected through a 525 nM bandpass filter on a linear scale . G. SIGNAL TRANSDUCTION STUDIES-PERTUSSIS TOXIN PMNs separated on percol gradients were...Clin. Immun. and Immunopath., 15:525, 1980. 16. Gray, G.D., Ohlmann, G.M., Morton. D.R. and Schaaub, R.G., Feline Polymorphonuclear Leukocytes Respond

  6. Homologation Reaction of Ketones with Diazo Compounds.

    PubMed

    Candeias, Nuno R; Paterna, Roberta; Gois, Pedro M P

    2016-03-09

    This review covers the addition of diazo compounds to ketones to afford homologated ketones, either in the presence or in the absence of promoters or catalysts. Reactions with diazoalkanes, aryldiazomethanes, trimethylsilyldiazomethane, α-diazo esters, and disubstituted diazo compounds are covered, commenting on the complex regiochemistry of the reaction and the nature of the catalysts and promoters. The recent reports on the enantioselective version of ketone homologation reactions are gathered in one section, followed by reports on the use of cyclic ketones ring expansion in total synthesis. Although the first reports of this reaction appeared in the literature almost one century ago, the recent achievements, in particular, for the asymmetric version, forecast the development of new breakthroughs in the synthetically valuable field of diazo chemistry.

  7. Remnants of an ancient pathway to L-phenylalanine and L-tyrosine in enteric bacteria: Evolutionary implications and biotechnological impact. [Escherichia coli; Salmonella typhimurium; Neurospora crassa

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bonner, C.A.; Fischer, R.S.; Ahmad, S.

    The pathway construction for biosynthesis of aromatic amino acids in Escherichia coli is atypical of the phylogenetic subdivision of gram-negative bacteria to which it belongs. Related organisms possess second pathways to phenylalanine and tyrosine which depend upon the expression of a monofunctional chorismate mutase (CM-F) and cyclohexadienyl dehydratase (CDT). Some enteric bacteria, unlike E. coli, possess either CM-F or CDT. These essentially cryptic remnants of an ancestral pathway can be a latent source of biochemical potential under certain conditions. As one example of advantageous biochemical potential, the presence of CM-F in Salmonella typhimurium increases the capacity for prephenate accumulation inmore » a tyrA auxotroph. We report the finding that a significant fraction of the latter prephenate is transaminated to L-arogenate. The tyrA19 mutant is now the organism of choice for isolation of L-arogenate, uncomplicated by the presence of other cyclohexadienyl products coaccumulated by a Neurospora crassa mutant that had previously served as the prime biological source of L-arogenate. Prephenate aminotransferase activity was not conferred by a discrete enzyme, but rather was found to be synonymous with the combined activities of aspartate aminotransferase (aspC), aromatic aminotransferase (tyrB), and branched-chain aminotransferase (ilvE).« less

  8. A root-expressed L-phenylalanine:4-hydroxyphenylpyruvate aminotransferase is required for tropane alkaloid biosynthesis in Atropa belladonna.

    PubMed

    Bedewitz, Matthew A; Góngora-Castillo, Elsa; Uebler, Joseph B; Gonzales-Vigil, Eliana; Wiegert-Rininger, Krystle E; Childs, Kevin L; Hamilton, John P; Vaillancourt, Brieanne; Yeo, Yun-Soo; Chappell, Joseph; DellaPenna, Dean; Jones, A Daniel; Buell, C Robin; Barry, Cornelius S

    2014-09-01

    The tropane alkaloids, hyoscyamine and scopolamine, are medicinal compounds that are the active components of several therapeutics. Hyoscyamine and scopolamine are synthesized in the roots of specific genera of the Solanaceae in a multistep pathway that is only partially elucidated. To facilitate greater understanding of tropane alkaloid biosynthesis, a de novo transcriptome assembly was developed for Deadly Nightshade (Atropa belladonna). Littorine is a key intermediate in hyoscyamine and scopolamine biosynthesis that is produced by the condensation of tropine and phenyllactic acid. Phenyllactic acid is derived from phenylalanine via its transamination to phenylpyruvate, and mining of the transcriptome identified a phylogenetically distinct aromatic amino acid aminotransferase (ArAT), designated Ab-ArAT4, that is coexpressed with known tropane alkaloid biosynthesis genes in the roots of A. belladonna. Silencing of Ab-ArAT4 disrupted synthesis of hyoscyamine and scopolamine through reduction of phenyllactic acid levels. Recombinant Ab-ArAT4 preferentially catalyzes the first step in phenyllactic acid synthesis, the transamination of phenylalanine to phenylpyruvate. However, rather than utilizing the typical keto-acid cosubstrates, 2-oxoglutarate, pyruvate, and oxaloacetate, Ab-ArAT4 possesses strong substrate preference and highest activity with the aromatic keto-acid, 4-hydroxyphenylpyruvate. Thus, Ab-ArAT4 operates at the interface between primary and specialized metabolism, contributing to both tropane alkaloid biosynthesis and the direct conversion of phenylalanine to tyrosine. © 2014 American Society of Plant Biologists. All rights reserved.

  9. Incorporation of sup 14 C from ( sup 14 C)phenylalanine into condensed tannin of sorghum grain

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Reddy, V.; Butler, L.G.

    A procedure is described for obtaining condensed tannin from sorghum (Sorghum bicolor (L.) Moench) seeds metabolically labeled from ({sup 14}C)phenylalanine. The ({sup 14}C)tannin should be useful in determining the metabolic fate of dietary condensed tannin.

  10. The influence of water-ethanol mixture on the thermodynamics of complex formation between 18-crown-6 ether and L-phenylalanine

    NASA Astrophysics Data System (ADS)

    Usacheva, T. R.; Sharnin, V. A.; Chernov, I. V.; Matteoli, E.; Terekhova, I. V.; Kumeev, R. S.

    2012-08-01

    The influence of water-ethanol mixture composition on the complex formation between 18-crown-6 ether and L-phenylalanine was studied by titration calorimetry at Т = 298.15 K. The standard thermodynamic parameters (ΔrGо, ΔrHо, ТΔrSо) of formation of [Phe18C6] molecular complex were calculated from data obtained by means of the microcalorimetric system TAM III (TA Instruments, USA) at X(EtOH) = 0.0/0.6 mol fraction. The stability of [Phe18C6] and the mechanism of complexation in water were investigated using the 1Н and 13С NMR spectroscopy. The increase of EtOH concentration results in an increase of the complex stability and of the exothermicity of complexation.

  11. Interaction between bioactive compound 11a-N-tosyl-5-deoxi-pterocarpan (LQB-223) and Calf thymus DNA: Spectroscopic approach, electrophoresis and theoretical studies.

    PubMed

    Silva, Marina M; Nascimento, Eduarda O O; Silva, Edeíldo F; Araújo, João Xavier de; Santana, Camilla C; Grillo, Luciano Aparecido M; de Oliveira, Rafaela S; R R Costa, Paulo; Buarque, Camilla D; Santos, Josué Carinhanha C; Figueiredo, Isis M

    2017-03-01

    The interaction of small molecules with DNA has been quite important, since this biomolecule is currently the major target for a wide range of drugs in clinical use or advanced clinical research phase. Thus, the present work aimed to assess the interaction process between the bioactive compound 11a-N-tosyl-5-carba-pterocarpan, (LQB-223), that presents antitumor activity, with DNA, employing spectroscopic techniques, electrophoresis, viscosity and theoretical studies. Through UV-vis and molecular fluorescence spectroscopy, it was possible to infer that the preferential quenching mechanism was static, characterized by non-fluorescent supramolecular complex formation between the LQB-223 and DNA. The binding constant was 1.94∙10 3 Lmol -1 (30°C) and, according to the thermodynamic parameters, the main forces involved in the interaction process are hydrophobic. Potassium iodide assay, competition with ethidium bromide, fluorescence contact energy transfer and melting temperature profile of DNA were employed to evaluate the binding mode. Except for KI assay, all results obtained indicated minor groove as the preferential binding mode of LQB-223 to DNA. These observations were supported by ionic strength assay, viscosity and molecular dynamics and docking studies. Finally, electrophoresis analysis demonstrated that the interaction does not promote DNA fragmentation, but it leads to variation in the migration profile after increasing the ligand concentration. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Effect of N-benzoyl-D-phenylalanine and metformin on carbohydrate metabolic enzymes in neonatal streptozotocin diabetic rats.

    PubMed

    Ashokkumar, Natarajan; Pari, Leelavinothan

    2005-01-01

    The effect of N-benzoyl-D-phenylalanine (NBDP) and metformin was studied on the activities of carbohydrate metabolic enzymes in neonatal streptozotocin (nSTZ) non-insulin-dependent diabetic rats. To induce non-insulin-dependent diabetes mellitus (NIDDM), single dose injection of streptozotocin (STZ; 100 mg/kg body weight; i.p.) was given to 2-day old rats. After 10-12 weeks, rats weighing >150 g were selected for screening in NIDDM model, they were checked for fasting blood glucose concentrations to conform the status of NIDDM. NBDP (50,100 and 200 mg/kg body weight) was administered orally for 6 weeks into the confirmed diabetic rats. The activities of gluconeogenic enzymes were significantly increased, whereas the activities of hexokinase and glucose-6-phosphate dehydrogenase were significantly decreased in nSTZ diabetic rats. Both NBDP and metformin were able to restore the altered enzyme activities to almost control concentrations. Combination treatment was more effective than either drug alone. The administration of NBDP along with metformin to nSTZ diabetic rats normalizes blood glucose and causes marked improvement of altered carbohydrate metabolic enzymes during diabetes.

  13. 5-(Chloromethyl)furfural is the New HMF: Functionally Equivalent But More Practical in Terms of its Production From Biomass.

    PubMed

    Mascal, Mark

    2015-10-26

    5-(Chloromethyl)furfural (CMF) is a disruptive innovation in the biorefinery. Chemically, it is at least as versatile as the well-known HMF but, unlike HMF, it is accessible in high yield directly from cellulosic biomass due to its lipophilicity and stability under acidic conditions, which facilitate isolation. It has a rich derivative chemistry that includes biofuels, renewable polymers, specialty chemicals, and value-added agrochemical and pharmaceutical products. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Chiral ligand-exchange high-performance liquid chromatography with copper (II)-L-phenylalanine complexes for separation of 3,4-dimethoxy-α-methylphenylalanine racemes.

    PubMed

    Jia, Dong-Xu; Ai, Zheng-Gui; Xue, Ya-Ping; Zheng, Yu-Guo

    2014-11-01

    L-3, 4-dimethoxy-α-methylphenylalanine (L-DMMD) is an important intermediate for the synthesis of 3-hydroxy-α-methyl-L-tyrosine (L-methyldopa). This paper describes an efficient, accurate, and low-priced method of high-performance liquid chromatography (HPLC) using chiral mobile phase and conventional C18 column to separate L-DMMD from its enantiomers. The effects of ligands, copper salts, organic modifiers, pHs of mobile phase, and temperatures on the retention factors (k') and selectivity (α) were evaluated to achieve optimal separation performance. Then, thermal analysis of the optimal separation conditions was investigated as well. It was confirmed that the optimal mobile phase was composed of 20 % (v/v) methanol, 8 mM L-phenylalanine (L-Phe), and 4 mM cupric sulfate in water of pH 3.2, and the column temperature was set at 20 °C. Baseline separation of two enantiomers could be obtained through the conventional C18 column with a resolution (R) of 3.18 in less than 18 min. Thermodynamic data (∆∆H and ∆∆S) obtained by Van't Hoff plots revealed the chiral separation was an enthalpy-controlled process. To the best of our knowledge, this is the first report regarding the enantioseparation of DMMD by chiral ligand-exchange HPLC.

  15. The vibrational spectroscopic studies and molecular property analysis of L-Phenylalanine using quantum chemical method

    NASA Astrophysics Data System (ADS)

    Borah, Mukunda Madhab; Devi, Th. Gomti

    2017-05-01

    In the present work, L-phenylalanine is studied using the experimental and theoretical methods. The spectral characterization of the molecule has been done using Raman, FTIR, Hartee-Fock(HF), density functional theory (DFT) and vibrational energy distribution analysis (VEDA) calculation. The optimization of the molecule has been studied using basis set HF/6-31G(d,p) and B3LYP/6-31G(d,p) for Hartree Fock and density functional theory calculation. The complete vibrational assignment of the molecule in monomer and dimer states have been attempted. The potential energy distribution and normal mode analysis are also carried out to determine the contributions of bond oscillators in each normal mode. The molecular geometry, HOMO-LUMO energy gap, molecular hardness (η), ionization energy (IE), electron affinity (EA), total energy and dipole moment were determined from the calculated data. The observed experimental and the scaled theoretical results are compared and found to be in good agreement. The vibrational assignment of molecule in different dimer states has also been done using SERS data and better correlated Raman peaks are observed as compare to normal Raman technique.

  16. Phenylalanine transfer across the isolated perfused human placenta: an experimental and modeling investigation

    PubMed Central

    Lofthouse, E. M.; Perazzolo, S.; Brooks, S.; Crocker, I. P.; Glazier, J. D.; Johnstone, E. D.; Panitchob, N.; Sibley, C. P.; Widdows, K. L.; Sengers, B. G.

    2015-01-01

    Membrane transporters are considered essential for placental amino acid transfer, but the contribution of other factors, such as blood flow and metabolism, is poorly defined. In this study we combine experimental and modeling approaches to understand the determinants of [14C]phenylalanine transfer across the isolated perfused human placenta. Transfer of [14C]phenylalanine across the isolated perfused human placenta was determined at different maternal and fetal flow rates. Maternal flow rate was set at 10, 14, and 18 ml/min for 1 h each. At each maternal flow rate, fetal flow rates were set at 3, 6, and 9 ml/min for 20 min each. Appearance of [14C]phenylalanine was measured in the maternal and fetal venous exudates. Computational modeling of phenylalanine transfer was undertaken to allow comparison of the experimental data with predicted phenylalanine uptake and transfer under different initial assumptions. Placental uptake (mol/min) of [14C]phenylalanine increased with maternal, but not fetal, flow. Delivery (mol/min) of [14C]phenylalanine to the fetal circulation was not associated with fetal or maternal flow. The absence of a relationship between placental phenylalanine uptake and net flux of phenylalanine to the fetal circulation suggests that factors other than flow or transporter-mediated uptake are important determinants of phenylalanine transfer. These observations could be explained by tight regulation of free amino acid levels within the placenta or properties of the facilitated transporters mediating phenylalanine transport. We suggest that amino acid metabolism, primarily incorporation into protein, is controlling free amino acid levels and, thus, placental transfer. PMID:26676251

  17. Elevated phenylalanine on newborn screening: follow-up testing may reveal undiagnosed galactosaemia.

    PubMed

    Shakespeare, Lynette; Downing, Melanie; Allen, Joyce; Casbolt, Ann-Marie; Ellin, Sheila; Maloney, Martin; Race, Gillian; Bonham, Jim

    2010-11-01

    Introduction Newborn screening for phenylketonuria (PKU) can reveal other conditions which lead to an increased blood spot phenylalanine (Phe) concentration. We have investigated the proportion of blood spot samples that gave a positive screen due to clinically significant conditions other than PKU, compared the positive predictive value (PPV) of our referral Phe cut-off with that recommended by the UK Newborn Screening Programme Centre (UKNSPC) (>210 and >240 μmol/L, respectively) and evaluated the effectiveness of reflex testing for galactosaemia using a lower blood spot Phe cut-off concentration of 130 μmol/L. All blood spot samples that screened positive, for an increased Phe concentration, between April 2001 and March 2008, were identified from the records of the Sheffield Newborn Screening Laboratory and the diagnoses noted. In addition, all cases of galactosaemia detected in or notified to our screening laboratory within this time were also examined and the screened Phe concentrations compared. Out of 438,674 babies who were screened, 67 had Phe concentration >210 μmol/L (15 per 100,000). Of these, 40 had PKU or persistent hyperphenylalaninaemia with a Phe concentration identified by screening between 270 and 2350 μmol/L. A further 11 were diagnosed with another clinically significant disorder: galactosaemia (n = 8), biopterin defects (n = 2), tyrosinaemia Type 1 (n = 1). In addition, 16 had transient elevations in Phe. In total, nine cases of galactosaemia were identified, of whom, three had Phe concentrations <240 μmol/L with one asymptomatic individual having a concentration <210 μmol/L. Adoption of the UKNSPC recommended cut-off (>240 μmol/L) will not affect the detection rate of classical PKU, but will improve the PPV from 76% to 80%. The use of a lower cut-off (130 μmol/L) for reflex galactosaemia testing enables the timely identification of asymptomatic cases that benefit particularly from early treatment, without prompting any unnecessary

  18. A mutation analysis of the phenylalanine hydroxylase (PAH) gene in the Israeli population.

    PubMed

    Bercovich, D; Elimelech, A; Yardeni, T; Korem, S; Zlotogora, J; Gal, N; Goldstein, N; Vilensky, B; Segev, R; Avraham, S; Loewenthal, R; Schwartz, G; Anikster, Y

    2008-05-01

    Hyperphenylalaninemia (HPA) is a group of diseases characterized by a persistent elevation of phenylalanine levels in tissues and biological fluids. The most frequent form is phenylalanine hydroxylase deficiency, causing phenylketonuria (PKU). Among 159 Israeli patients (Jews, Muslim and Christian Arabs and Druze) with HPA, in whom at least one of the mutations was characterized, a total of 43 different mutations were detected, including seven novel ones. PKU was very rare among Ashkenazi Jews and relatively frequent among Jews from Yemen, the Caucasian Mountains, Bukhara and Tunisia. The mutations responsible for the high frequency were: exon3del (Yemenite Jews), L48S (Tunisian Jews) and E178G, P281L and L48S (Jews from the Caucasian Mountains and Bukhara). Among the non-Jewish Israeli citizens, the disease was relatively frequent in the Negev and in the Nazareth vicinity, and in many localities a unique mutation was detected, often in a single family. While marked genetic heterogeneity was observed in the Arab and Jewish populations, only one mutation A300S, was frequent in all of the communities. Several of the other frequent mutations were shared by the non-Ashkenazi Jews and Arabs; none were mutual to Ashkenazi Jews and Arabs.

  19. The collective therapeutic potential of cerebral ketone metabolism in traumatic brain injury

    PubMed Central

    Prins, Mayumi L.; Matsumoto, Joyce H.

    2014-01-01

    The postinjury period of glucose metabolic depression is accompanied by adenosine triphosphate decreases, increased flux of glucose through the pentose phosphate pathway, free radical production, activation of poly-ADP ribose polymerase via DNA damage, and inhibition of glyceraldehyde dehydrogenase (a key glycolytic enzyme) via depletion of the cytosolic NAD pool. Under these post-brain injury conditions of impaired glycolytic metabolism, glucose becomes a less favorable energy substrate. Ketone bodies are the only known natural alternative substrate to glucose for cerebral energy metabolism. While it has been demonstrated that other fuels (pyruvate, lactate, and acetyl-L-carnitine) can be metabolized by the brain, ketones are the only endogenous fuel that can contribute significantly to cerebral metabolism. Preclinical studies employing both pre- and postinjury implementation of the ketogenic diet have demonstrated improved structural and functional outcome in traumatic brain injury (TBI) models, mild TBI/concussion models, and spinal cord injury. Further clinical studies are required to determine the optimal method to induce cerebral ketone metabolism in the postinjury brain, and to validate the neuroprotective benefits of ketogenic therapy in humans. PMID:24721741

  20. Ketone bodies and two-compartment tumor metabolism

    PubMed Central

    Martinez-Outschoorn, Ubaldo E.; Lin, Zhao; Whitaker-Menezes, Diana; Howell, Anthony; Lisanti, Michael P.; Sotgia, Federica

    2012-01-01

    We have previously suggested that ketone body metabolism is critical for tumor progression and metastasis. Here, using a co-culture system employing human breast cancer cells (MCF7) and hTERT-immortalized fibroblasts, we provide new evidence to directly support this hypothesis. More specifically, we show that the enzymes required for ketone body production are highly upregulated within cancer-associated fibroblasts. This appears to be mechanistically controlled by the stromal expression of caveolin-1 (Cav-1) and/or serum starvation. In addition, treatment with ketone bodies (such as 3-hydroxy-butyrate, and/or butanediol) is sufficient to drive mitochondrial biogenesis in human breast cancer cells. This observation was also validated by unbiased proteomic analysis. Interestingly, an MCT1 inhibitor was sufficient to block the onset of mitochondrial biogenesis in human breast cancer cells, suggesting a possible avenue for anticancer therapy. Finally, using human breast cancer tumor samples, we directly confirmed that the enzymes associated with ketone body production (HMGCS2, HMGCL and BDH1) were preferentially expressed in the tumor stroma. Conversely, enzymes associated with ketone re-utilization (ACAT1) and mitochondrial biogenesis (HSP60) were selectively associated with the epithelial tumor cell compartment. Our current findings are consistent with the “two-compartment tumor metabolism” model. Furthermore, they suggest that we should target ketone body metabolism as a new area for drug discovery, for the prevention and treatment of human cancers. PMID:23082721

  1. Mechanistic, Mutational, and Structural Evaluation of a Taxus Phenylalanine Aminomutase

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Feng, Lei; Wanninayake, Udayanga; Strom, Susan

    The structure of a phenylalanine aminomutase (TcPAM) from Taxus canadensis has been determined at 2.4 {angstrom} resolution. The active site of the TcPAM contains the signature 4-methylidene-1H-imidazol-5(4H)-one prosthesis, observed in all catalysts of the class I lyase-like family. This catalyst isomerizes (S)-{alpha}-phenylalanine to the (R)-{beta}-isomer by exchange of the NH{sub 2}/H pair. The stereochemistry of the TcPAM reaction product is opposite of the (S)-{beta}-tyrosine made by the mechanistically related tyrosine aminomutase (SgTAM) from Streptomyces globisporus. Since TcPAM and SgTAM share similar tertiary- and quaternary-structures and have several highly conserved aliphatic residues positioned analogously in their active sites for substrate recognition,more » the divergent product stereochemistries of these catalysts likely cannot be explained by differences in active site architecture. The active site of the TcPAM structure also is in complex with (E)-cinnamate; the latter functions as both a substrate and an intermediate. To account for the distinct (3R)-{beta}-amino acid stereochemistry catalyzed by TcPAM, the cinnamate skeleton must rotate the C{sub 1}-C{sub {alpha}} and C{sub ipso}-C{sub {beta}} bonds 180{sup o} in the active site prior to exchange and rebinding of the NH{sub 2}/H pair to the cinnamate, an event that is not required for the corresponding acrylate intermediate in the SgTAM reaction. Moreover, the aromatic ring of the intermediate makes only one direct hydrophobic interaction with Leu-104. A L104A mutant of TcPAM demonstrated an 1.5-fold increase in k{sub cat} and a decrease in K{sub M} values for sterically demanding 3'-methyl-{alpha}-phenylalanine and styryl-{alpha}-alanine substrates, compared to the kinetic parameters for TcPAM. These parameters did not change significantly for the mutant with 4'-methyl-{alpha}-phenylalanine compared to those for TcPAM.« less

  2. Synthesis and antimicrobial evaluation of L-phenylalanine-derived C5-substituted rhodanine and chalcone derivatives containing thiobarbituric acid or 2-thioxo-4-thiazolidinone.

    PubMed

    Jin, Xin; Zheng, Chang-Ji; Song, Ming-Xia; Wu, Yan; Sun, Liang-Peng; Li, Yin-Jing; Yu, Li-Jun; Piao, Hu-Ri

    2012-10-01

    Four novel series of compounds, including the l-phenylalanine-derived C5-substituted rhodanine (6a-q, 7a-j) and chalcone derivatives containing thiobarbituric acid or 2-thioxo-4-thiazolidinone (9a-e, 11a-e) have been designed, synthesized, characterized, and evaluated for their antibacterial activity. Some of these compounds showed significant antibacterial activity against Gram-positive bacterias, especially against the strains of multidrug-resistant clinical isolates, among which compounds 6c-e, 6g, 6i, 6j and 6q exhibiting high levels of antimicrobial activity against Staphylococcus aureus RN4220 with minimum inhibitory concentration (MIC) values of 2 μg/mL. Compound 6q showed the most potent activity of all of the compounds against all of the test multidrug-resistant clinical isolates tested. Unfortunately, however, none of the compounds were active against Gram-negative bacteria at 64 μg/mL. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  3. Benzoyl radicals from (hetero)aromatic aldehydes. Decatungstate photocatalyzed synthesis of substituted aromatic ketones.

    PubMed

    Ravelli, Davide; Zema, Michele; Mella, Mariella; Fagnoni, Maurizio; Albini, Angelo

    2010-09-21

    Benzoyl radicals are generated directly from (hetero)aromatic aldehydes upon tetrabutylammonium decatungstate ((n-Bu(4)N)(4)W(10)O(32)), TBADT) photocatalysis under mild conditions. In the presence of alpha,beta-unsaturated esters, ketones and nitriles radical conjugate addition ensues and gives the corresponding beta-functionalized aryl alkyl ketones in moderate to good yields (stereoselectively in the case of 3-methylene-2-norbornanone). Due to the mild reaction conditions the presence of various functional groups on the aromatic ring is tolerated (e.g. methyl, methoxy, chloro). The method can be applied to hetero-aromatic aldehydes whether electron-rich (e.g. thiophene-2-carbaldehyde) or electron-poor (e.g. pyridine-3-carbaldehyde).

  4. Recommendations for the nutrition management of phenylalanine hydroxylase deficiency

    PubMed Central

    Singh, Rani H.; Rohr, Fran; Frazier, Dianne; Cunningham, Amy; Mofidi, Shideh; Ogata, Beth; Splett, Patricia L.; Moseley, Kathryn; Huntington, Kathleen; Acosta, Phyllis B.; Vockley, Jerry; Van Calcar, Sandra C.

    2014-01-01

    The effectiveness of a phenylalanine-restricted diet to improve the outcome of individuals with phenylalanine hydroxylase deficiency (OMIM no. 261600) has been recognized since the first patients were treated 60 years ago. However, the treatment regime is complex, costly, and often difficult to maintain for the long term. Improvements and refinements in the diet for phenylalanine hydroxylase deficiency have been made over the years, and adjunctive therapies have proven to be successful for certain patients. Yet evidence-based guidelines for managing phenylalanine hydroxylase deficiency, optimizing outcomes, and addressing all available therapies are lacking. Thus, recommendations for nutrition management were developed using evidence from peer-reviewed publications, gray literature, and consensus surveys. The areas investigated included choice of appropriate medical foods, integration of adjunctive therapies, treatment during pregnancy, monitoring of nutritional and clinical markers, prevention of nutrient deficiencies, providing of access to care, and compliance strategies. This process has not only provided assessment and refinement of current nutrition management and monitoring recommendations but also charted a direction for future studies. This document serves as a companion to the concurrently published American College of Medical Genetics and Genomics guideline for the medical treatment of phenylalanine hydroxylase deficiency. Genet Med 16 2, 121–131. PMID:24385075

  5. Copper-catalyzed aerobic oxidative coupling: From ketone and diamine to pyrazine

    PubMed Central

    Wu, Kun; Huang, Zhiliang; Qi, Xiaotian; Li, Yingzi; Zhang, Guanghui; Liu, Chao; Yi, Hong; Meng, Lingkui; Bunel, Emilio E.; Miller, Jeffrey T.; Pao, Chih-Wen; Lee, Jyh-Fu; Lan, Yu; Lei, Aiwen

    2015-01-01

    Copper-catalyzed aerobic oxidative C–H/N–H coupling between simple ketones and diamines was developed toward the synthesis of a variety of pyrazines. Various substituted ketones were compatible for this transformation. Preliminary mechanistic investigations indicated that radical species were involved. X-ray absorption fine structure experiments elucidated that the Cu(II) species 5 coordinated by two N atoms at a distance of 2.04 Å and two O atoms at a shorter distance of 1.98 Å was a reactive one for this aerobic oxidative coupling reaction. Density functional theory calculations suggested that the intramolecular coupling of cationic radicals was favorable in this transformation. PMID:26601302

  6. Leptin controls ketone body utilization in hypothalamic neuron.

    PubMed

    Narishima, Ryota; Yamasaki, Masahiro; Hasegawa, Shinya; Yoshida, Saki; Tanaka, Shinya; Fukui, Tetsuya

    2011-03-03

    Leptin is an appetite-controlling peptide secreted from adipose tissue. Previously, we showed that the gene expression of acetoacetyl-CoA synthetase (AACS), the ketone body-utilizing enzyme for lipid synthesis, was suppressed by leptin deficiency-induced obesity in white adipose tissue. In this study, to clarify the effects of leptin on ketone body utilization in the central nervous system, we examined the effects of leptin signaling on AACS expression. In situ hybridization analysis of ob/ob and db/db mice revealed that AACS mRNA level was reduced by leptin deficiency in the arcuate nucleus (Arc) and ventromedial hypothalamic nucleus (VMH) in hypothalamus but not in other brain regions. Moreover, AACS mRNA level was increased by leptin treatment both in primary cultured neural cells and in N41 neural-like cells. In N41 cells, AACS level was decreased by AMPK inducer but increased by AMPK inhibitor. These results suggest that the up-regulation of AACS expression by leptin is due to the suppression of AMPK activity via neural leptin signaling and that the deficiency of this regulation may be responsible for neurological disorders in central appetite control. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  7. Peripheral vascular effects of bretylium tosylate in man.

    PubMed

    Blair, D A; Glover, W E; Kidd, B S; Roddie, I C

    1960-09-01

    After intra-arterial infusion of bretylium tosylate (12.5 mg.), the reflex changes in vasoconstrictor tone which normally occur in the forearm with body cooling, positive pressure breathing, the Valsalva manoeuvre and postural change were greatly reduced or abolished. Reflex vasodilatation mediated by cholinergic fibres in response to body heating or to emotional stress was little affected. It was concluded that bretylium can selectively block the activity of sympathetic noradrenergic fibres without causing a similar block of sympathetic cholinergic fibres. As the responses to intravenous or intra-arterial infusions of adrenaline or noradrenaline were not reduced after bretylium, it was concluded that bretylium interferes with the activity of noradrenergic fibres rather than with the activity of the noradrenaline released at the nerve ending. After bretylium infusion, forearm and hand blood flow did not often rise to levels characteristic of full release of vasoconstrictor tone. As infusion of bretylium into a nerve-blocked forearm resulted in a pronounced reduction in flow, it is concluded that bretylium also has a constrictor effect on blood vessels. The state of the vessels following an infusion of bretylium appears to depend on the balance between this constrictor action and the longer-acting sympathetic blocking effect.

  8. Sirtuin 3 mediates neuroprotection of ketones against ischemic stroke

    PubMed Central

    Yin, Junxiang; Han, Pengcheng; Tang, Zhiwei; Liu, Qingwei; Shi, Jiong

    2015-01-01

    Stroke is one of the leading causes of death. Growing evidence indicates that ketone bodies have beneficial effects in treating stroke, but their underlying mechanism remains unclear. Our previous study showed ketone bodies reduced reactive oxygen species by using NADH as an electron donor, thus increasing the NAD+/NADH ratio. In this study, we investigated whether mitochondrial NAD+-dependent Sirtuin 3 (SIRT3) could mediate the neuroprotective effects of ketone bodies after ischemic stroke. We injected mice with either normal saline or ketones (beta-hydroxybutyrate and acetoacetate) at 30 minutes after ischemia induced by transient middle cerebral artery (MCA) occlusion. We found that ketone treatment enhanced mitochondria function, reduced oxidative stress, and therefore reduced infarct volume. This led to improved neurologic function after ischemia, including the neurologic score and the performance in Rotarod and open field tests. We further showed that ketones' effects were achieved by upregulating NAD+-dependent SIRT3 and its downstream substrates forkhead box O3a (FoxO3a) and superoxide dismutase 2 (SOD2) in the penumbra region since knocking down SIRT3 in vitro diminished ketones' beneficial effects. These results provide us a foundation to develop novel therapeutics targeting this SIRT3-FoxO3a-SOD2 pathway. PMID:26058697

  9. Serum phenylalanine in preterm newborns fed different diets of human milk.

    PubMed

    Thomaz, Débora M; Serafin, Paula O; Palhares, Durval B; Tavares, Luciana V M; Grance, Thayana R S

    2014-01-01

    To evaluate phenylalanine plasma profile in preterm newborns fed different human milk diets. Twenty-four very-low weight preterm newborns were distributed randomly in three groups with different feeding types: Group I: banked human milk plus 5% commercial fortifier with bovine protein, Group II: banked human milk plus evaporated fortifier derived from modified human milk, Group III: banked human milk plus lyophilized fortifier derived from modified human milk. The newborns received the group diet when full diet was attained at 15 ± 2 days. Plasma amino acid analysis was performedon the first and last day of feeding. Comparison among groups was performed by statistical tests: one way ANOVA with Tukey's post-test using SPSS software, version 20.0 (IBM Corp, NY, USA), considering a significance level of 5%. Phenylalanine levels in the first and second analysis were, respectively, in Group I: 11.9 ± 1.22 and 29.72 ± 0.73; in Group II: 11.72 ± 1.04 and 13.44 ± 0.61; and in Group III: 11.3 ± 1.18 and 15.42 ± 0.83 μmol/L. The observed results demonstrated that human milk with fortifiers derived from human milk acted as a good substratum for preterm infant feeding both in the evaporated or the lyophilized form, without significant increases in plasma phenylalanine levels in comparison to human milk with commercial fortifier. Copyright © 2014 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

  10. L-Arogenate is a chemoattractant which can be utilized as the sole source of carbon and nitrogen by Pseudomonas aeruginosa

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Fischer, R.S.; Song, Jian; Gu, Wei

    L-Arogenate is a commonplace amino acid in nature in consideration of its role as a ubiquitous precursor of L-phenylalanine and/or L-tyrosine. However, the questions of whether it serves as a chemoattractant molecule and whether it can serve as a substrate for catabolism have never been studied. We found that Pseudomonas aeruginosa recognizes L-arogenate as a chemoattractant molecule which can be utilized as a source of both carbon and nitrogen. Mutants lacking expression of either cyclohexadienyl dehydratase or phenylalanine hydroxylase exhibited highly reduced growth rates when utilizing L-arogenate as a nitrogen source. Utilization of L-arogenate as a source of either carbonmore » or nitrogen was dependent upon {sub S}{sup 54}, as revealed by the use of an rpoN null mutant. The evidence suggests that catabolism of L-arogenate proceeds via alternative pathways which converge at 4-hydroxyphenylpyruvate. In one pathway, prephenate formed in the periplasm by deamination of L-arogenate is converted to 4-hydroxyphenylpyruvate by cyclohexadienyl dehydrogenase. The second route depends upon the sequential action of periplasmic cyclohexadienyl dehydratase, phenylalanine hydroxylase, and aromatic aminotransferase. 32 refs., 5 figs., 4 tabs.« less

  11. Chymotryptic specificity determinants in the 1.0 Å structure of the zinc-inhibited human tissue kallikrein 7

    PubMed Central

    Debela, Mekdes; Hess, Petra; Magdolen, Viktor; Schechter, Norman M.; Steiner, Thomas; Huber, Robert; Bode, Wolfram; Goettig, Peter

    2007-01-01

    hK7 or human stratum corneum chymotryptic enzyme belongs to the human tissue kallikrein (hKs) serine proteinase family and is strongly expressed in the upper layers of the epidermis. It participates in skin desquamation but is also implicated in diverse skin diseases and is a potential biomarker of ovarian cancer. We have solved x-ray structures of recombinant active hK7 at medium and atomic resolution in the presence of the inhibitors succinyl-Ala-Ala-Pro-Phe-chloromethyl ketone and Ala-Ala-Phe-chloromethyl ketone. The most distinguishing features of hK7 are the short 70–80 loop and the unique S1 pocket, which prefers P1 Tyr residues, as shown by kinetic data. Similar to several other kallikreins, the enzyme activity is inhibited by Zn2+ and Cu2+ at low micromolar concentrations. Biochemical analyses of the mutants H99A and H41F confirm that only the metal-binding site at His99 close to the catalytic triad accounts for the noncompetitive Zn2+ inhibition type. Additionally, hK7 exhibits large positively charged surface patches, representing putative exosites for prime side substrate recognition. PMID:17909180

  12. [DL-phenylalanine as an antidepressant. Open study (author's transl)].

    PubMed

    Beckmann, H; Ludolph, E

    1978-01-01

    In an open study dl-phenylalanine in doses from 75--200 mg/day was administered to 20 depressed patients for 20 days. At the end of the trial 12 patients (8 with complete, 4 with good response) could be discharged without any further treatment. 4 patients with partially untypical depressions experienced mild to moderate responses, whereas 4 patients did not respond at all to the phenylalanine administration. Depressive "core symptoms" as depressed mood, retardation and/or agitation were preferentially, anxiety and sleep disturbances moderately and hypochondriasis and compulsiveness were not influenced. It is concluded that dl-phenylalanine might have substantial antidepressant properties and that further controlled investigations are justified.

  13. An experimental study of the combined effects of n-hexane and methyl ethyl ketone.

    PubMed Central

    Takeuchi, Y; Ono, Y; Hisanaga, N; Iwata, M; Aoyama, M; Kitoh, J; Sugiura, Y

    1983-01-01

    This study was intended to determine whether or not methyl ethyl ketone (MEK) enhances the neurotoxicity of n-hexane at low concentration and after long term exposure. Separate groups of eight rats were exposed to 100 ppm n-hexane, 200 ppm MEK, 100 ppm n-hexane plus 200 ppm MEK, or fresh air in an exposure chamber for 12 hours a day for 24 weeks. The body weight, motor nerve conduction velocity (MCV), distal motor latency (DL), and mixed nerve conduction velocities (MNCVs) were measured before exposure and after four, eight, 12, 16, 20, and 24 weeks' exposure. One rat of each group was histopathologically examined after 24 weeks' exposure. Exposure of 100 ppm n-hexane did not significantly decrease the functions of the peripheral nerve throughout the experiment. Exposure to 200 ppm MEK significantly increased MCV and MNCVs and decreased DL after four weeks' exposure, but at this later stage no significant changes were found throughout the experiment by comparison with the controls. Mixed exposure to 100 ppm n-hexane plus 200 ppm MEK significantly decreased by comparison with the controls. On histopathological examination of the tail nerve, however, no changes were found in any of the exposed groups or the controls. These results suggest that MEK might enhance the neurotoxicity of n-hexane at a low concentration, and mixed exposures to n-hexane and MEK should be avoided. PMID:6830718

  14. Structure-activity relationships among substituted N-benzoyl derivatives of phenylalanine and its analogues in a microbial antitumor prescreen III: derivatives of p-fluoro-DL-phenylalanine.

    PubMed

    Otani, T T; Briley, M R

    1985-01-01

    Twelve substituted benzoyl derivatives of p-fluoro-DL-phenylalanine were prepared and tested for growth-inhibitory activity in a Lactobacillus casei system used as an antitumor prescreen. The 12 substituted benzoyl groups were the same as those attached to o-fluorophenylalanine and m-fluorophenylalanine studied earlier. The activity of these compounds was compared vertically among themselves and horizontally with the corresponding derivatives of o-fluorophenylalanine and of m-fluorophenylalanine. It was found that the derivatives of p-fluorophenylalanine, like those of o- and m-fluorophenylalanine, exhibited remarkable inhibition, all but one, i.e., the o-nitrobenzoyl derivative, showing inhibition that is considered to be positive in the prescreen. Particularly potent compounds in this group were the m-chlorobenzoyl-, p-chlorobenzoyl, m-nitrobenzoyl, and p-nitrobenzoyl derivatives. Comparison of the activity of the substituted benzoyl derivatives of all three structural isomers of fluorophenylalanine at equimolar concentrations showed that the derivatives of m-fluorophenylalanine were generally better inhibitors than those of o-fluoro- or p-fluorophenylalanine. Study of the ID50 values of the more active substituted benzoyl derivatives of the fluorophenylalanines showed that the most active of this group was m-chlorobenzoyl-p-fluoro-DL-phenylalanine.

  15. Synthesis, micellisation and interaction of novel quaternary ammonium compounds derived from l-Phenylalanine with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine as model membrane in relation to their antibacterial activity, and their selectivity over human red blood cells.

    PubMed

    Joondan, Nausheen; Caumul, Prakashanand; Akerman, Matthew; Jhaumeer-Laulloo, Sabina

    2015-02-01

    A series of quaternary ammonium compounds (QUATS) derived from l-Phenylalanine have been synthesized and their antibacterial efficiencies were determined against various strains of Gram-positive and Gram-negative bacteria. The antibacterial activity increased with increasing chain length, exhibiting a cut-off effect at C14 for Gram-positive and C12 for Gram-negative bacteria. The l-Phenylalanine QUATS displayed enhanced antibacterial properties with a higher cut-off point compared to their corresponding l-Phenylalanine ester hydrochlorides. The CMC was correlated with the MIC, inferring that micellar activity contributes to the cut-off effect in antibacterial activity. The hemolytic activities (HC50) of the QUATS against human red blood cells were also determined to illustrate the selectivity of these QUATS for bacterial over mammalian cells. In general, the MIC was lower than the HC50, and assessment of the micellar contribution to the antibacterial and hemolytic evaluation in TBS as a common medium confirmed that these QUATS can act as antibacterial, yet non-toxic molecules at their monomer concentrations. The interaction of the QUATS with the phospholipid vesicles (1,2-dipalmitoyl-sn-glycero-3-phosphocholine, DPPC) in the presence of 1-anilino-8-naphthalene sulfonate (ANS) and 1,6-diphenyl-1,3,5-hexatriene (DPH) as fluorescence probes showed that the presence of the quaternary ammonium moiety causes an increase in hydrophobic interactions, thus causing an increase in antibacterial activity. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. An additional substrate binding site in a bacterial phenylalanine hydroxylase

    PubMed Central

    Ronau, Judith A.; Paul, Lake N.; Fuchs, Julian E.; Corn, Isaac R.; Wagner, Kyle T.; Liedl, Klaus R.; Abu-Omar, Mahdi M.; Das, Chittaranjan

    2014-01-01

    Phenylalanine hydroxylase (PAH) is a non-heme iron enzyme that catalyzes phenylalanine oxidation to tyrosine, a reaction that must be kept under tight regulatory control. Mammalian PAH features a regulatory domain where binding of the substrate leads to allosteric activation of the enzyme. However, existence of PAH regulation in evolutionarily distant organisms, such as certain bacteria in which it occurs, has so far been underappreciated. In an attempt to crystallographically characterize substrate binding by PAH from Chromobacterium violaceum (cPAH), a single-domain monomeric enzyme, electron density for phenylalanine was observed at a distal site, 15.7Å from the active site. Isothermal titration calorimetry (ITC) experiments revealed a dissociation constant of 24 ± 1.1 µM for phenylalanine. Under the same conditions, no detectable binding was observed in ITC for alanine, tyrosine, or isoleucine, indicating the distal site may be selective for phenylalanine. Point mutations of residues in the distal site that contact phenylalanine (F258A, Y155A, T254A) lead to impaired binding, consistent with the presence of distal site binding in solution. Kinetic analysis reveals that the distal site mutants suffer a discernible loss in their catalytic activity. However, x-ray structures of Y155A and F258A, two of the mutants showing more noticeable defect in their activity, show no discernible change in their active site structure, suggesting that the effect of distal binding may transpire through protein dynamics in solution. PMID:23860686

  17. The Kinetic Mechanism of Phenylalanine Hydroxylase: Intrinsic Binding and Rate Constants from Single Turnover Experiments†

    PubMed Central

    Roberts, Kenneth M.; Pavon, Jorge Alex; Fitzpatrick, Paul F.

    2013-01-01

    Phenylalanine hydroxylase (PheH) catalyzes the key step in the catabolism of dietary phenylalanine, its hydroxylation to tyrosine using tetrahydrobiopterin (BH4) and O2. A complete kinetic mechanism for PheH was determined by global analysis of single turnover data in the reaction of PheHΔ117, a truncated form of the enzyme lacking the N-terminal regulatory domain. Formation of the productive PheHΔ117-BH4-phenylalanine complex begins with the rapid binding of BH4 (Kd = 65 µM). Subsequent addition of phenylalanine to the binary complex to form the productive ternary complex (Kd = 130 µM) is approximately ten-fold slower. Both substrates can also bind to the free enzyme to form inhibitory binary complexes. O2 rapidly binds to the productive ternary complex; this is followed by formation of an unidentified intermediate, detectable as a decrease in absorbance at 340 nm, with a rate constant of 140 s−1. Formation of the 4a-hydroxypterin and Fe(IV)O intermediates is ten-fold slower and is followed by the rapid hydroxylation of the amino acid. Product release is the rate-determining step and largely determines kcat. Similar reactions using 6-methyltetrahydropterin indicate a preference for the physiological pterin during hydroxylation. PMID:23327364

  18. Binding of radiation-induced phenylalanine radicals to DNA: influence on the biological activity of the DNA and on its sensitivity to the induction of breaks by gamma rays

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Vanderschans, G.P.; Vanrijn, C.J.S.; Bleichrodt, J.F.

    1975-11-01

    When an aqueous solution of double-stranded deoxyribonucleic acid (DNA) of bacteriophage PM2 containing phenylalanine and saturated with N2O is irradiated with gamma rays, radiation induced phenylalanine radicals are bound covalently. Under the conditions used about 25 phenylalanine molecules may be bound per lethal hit. Also for single-stranded PM2 DNA most of the phenylalanine radicals bound are nonlethal. Evidence is presented that in double-stranded DNA an appreciable fraction of the single-strand breaks is induced by phenylalanine radicals. Radiation products of phenylalanine and the phenylalanine bound to the DNA decrease the sensitivity of the DNA to the induction of single-strand breaks. Theremore » are indications that the high efficiency of protection by radiation products of phenylalanine is due to their positive charge, which will result in a relatively high concentration of these compounds in the vicinity of the negatively charged DNA molecules. (Author) (GRA)« less

  19. Colorimetric Recognition of Aldehydes and Ketones.

    PubMed

    Li, Zheng; Fang, Ming; LaGasse, Maria K; Askim, Jon R; Suslick, Kenneth S

    2017-08-07

    A colorimetric sensor array has been designed for the identification of and discrimination among aldehydes and ketones in vapor phase. Due to rapid chemical reactions between the solid-state sensor elements and gaseous analytes, distinct color difference patterns were produced and digitally imaged for chemometric analysis. The sensor array was developed from classical spot tests using aniline and phenylhydrazine dyes that enable molecular recognition of a wide variety of aliphatic or aromatic aldehydes and ketones, as demonstrated by hierarchical cluster, principal component, and support vector machine analyses. The aldehyde/ketone-specific sensors were further employed for differentiation among and identification of ten liquor samples (whiskies, brandy, vodka) and ethanol controls, showing its potential applications in the beverage industry. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Lanthanum tricyanide-catalyzed acyl silane-ketone benzoin additions.

    PubMed

    Tarr, James C; Johnson, Jeffrey S

    2009-09-03

    Lanthanum tricyanide efficiently catalyzes a benzoin-type coupling between acyl silanes and ketones. Yields range from moderate to excellent over a broad substrate scope encompassing aryl, alkyl, electron-rich, and sterically hindered ketones.

  1. Fluorescent Biphenyl Derivatives of Phenylalanine Suitable for Protein Modification

    PubMed Central

    Chen, Shengxi; Fahmi, Nour Eddine; Bhattacharya, Chandrabali; Wang, Lin; Jin, Yuguang; Benkovic, Stephen J.; Hecht, Sidney M.

    2013-01-01

    In a recent study, we demonstrated that structurally compact fluorophores incorporated into the side chains of amino acids could be introduced into dihydrofolate reductase from E. coli (ecDHFR) with minimal disruption of protein structure or function, even where the site of incorporation was within a folded region of the protein. The modified proteins could be employed for FRET measurements, providing sensitive monitors of changes in protein conformation. The very favorable results achieved in that study encouraged us to prepare additional fluorescent amino acids of potential utility for studying protein dynamics. Presently, we describe the synthesis and photophysical characterization of four positional isomers of biphenyl-phenylalanine, all of which were found to exhibit potentially useful fluorescent properties. All four phenylalanine derivatives were used to activate suppressor tRNA transcripts, and incorporated into multiple positions of ecDHFR. All phenylalanine derivatives were incorporated with good efficiency into position 16 of ecDHFR, and afforded modified proteins which consumed NADPH at rates up to about twice the rate measured for wild type. This phenomenon has been noted on a number of occasions previously and shown to be due to an increase in the off-rate of tetrahydrofolate from the enzyme, altering a step that is normally rate limiting. When introduced into sterically accessible position 49, the four phenylalanine derivatives afforded DHFRs having catalytic function comparable to wild type. The four phenylalanine derivatives were also introduced into position 115 of ecDHFR, which is known to be a folded region of the protein less tolerant of structural alteration. As anticipated, significant differences were noted in the catalytic efficiencies of the derived proteins. The ability of two of the sizeable biphenyl-phenylalanine derivatives to be accommodated at position 115 with minimal perturbation of DHFR function is attributed to rotational

  2. 27 CFR 21.117 - Methyl isobutyl ketone.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Methyl isobutyl ketone. 21.117 Section 21.117 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU....117 Methyl isobutyl ketone. (a) Acidity (as acetic acid). 0.02 percent by weight, maximum. (b) Color...

  3. 27 CFR 21.117 - Methyl isobutyl ketone.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Methyl isobutyl ketone. 21.117 Section 21.117 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU....117 Methyl isobutyl ketone. (a) Acidity (as acetic acid). 0.02 percent by weight, maximum. (b) Color...

  4. A Root-Expressed l-Phenylalanine:4-Hydroxyphenylpyruvate Aminotransferase Is Required for Tropane Alkaloid Biosynthesis in Atropa belladonna[C][W

    PubMed Central

    Bedewitz, Matthew A.; Góngora-Castillo, Elsa; Uebler, Joseph B.; Gonzales-Vigil, Eliana; Wiegert-Rininger, Krystle E.; Childs, Kevin L.; Hamilton, John P.; Vaillancourt, Brieanne; Yeo, Yun-Soo; Chappell, Joseph; DellaPenna, Dean; Jones, A. Daniel; Buell, C. Robin; Barry, Cornelius S.

    2014-01-01

    The tropane alkaloids, hyoscyamine and scopolamine, are medicinal compounds that are the active components of several therapeutics. Hyoscyamine and scopolamine are synthesized in the roots of specific genera of the Solanaceae in a multistep pathway that is only partially elucidated. To facilitate greater understanding of tropane alkaloid biosynthesis, a de novo transcriptome assembly was developed for Deadly Nightshade (Atropa belladonna). Littorine is a key intermediate in hyoscyamine and scopolamine biosynthesis that is produced by the condensation of tropine and phenyllactic acid. Phenyllactic acid is derived from phenylalanine via its transamination to phenylpyruvate, and mining of the transcriptome identified a phylogenetically distinct aromatic amino acid aminotransferase (ArAT), designated Ab-ArAT4, that is coexpressed with known tropane alkaloid biosynthesis genes in the roots of A. belladonna. Silencing of Ab-ArAT4 disrupted synthesis of hyoscyamine and scopolamine through reduction of phenyllactic acid levels. Recombinant Ab-ArAT4 preferentially catalyzes the first step in phenyllactic acid synthesis, the transamination of phenylalanine to phenylpyruvate. However, rather than utilizing the typical keto-acid cosubstrates, 2-oxoglutarate, pyruvate, and oxaloacetate, Ab-ArAT4 possesses strong substrate preference and highest activity with the aromatic keto-acid, 4-hydroxyphenylpyruvate. Thus, Ab-ArAT4 operates at the interface between primary and specialized metabolism, contributing to both tropane alkaloid biosynthesis and the direct conversion of phenylalanine to tyrosine. PMID:25228340

  5. Lanthanum Tricyanide-Catalyzed Acyl Silane-Ketone Benzoin Additions

    PubMed Central

    Tarr, James C.; Johnson, Jeffrey S.

    2009-01-01

    Lanthanum tricyanide efficiently catalyzes a benzoin-type coupling between acyl silanes and ketones. Yields range from moderate to excellent over a broad substrate scope encompassing aryl, alkyl, electron-rich, and sterically hindered ketones. PMID:19655731

  6. The collective therapeutic potential of cerebral ketone metabolism in traumatic brain injury.

    PubMed

    Prins, Mayumi L; Matsumoto, Joyce H

    2014-12-01

    The postinjury period of glucose metabolic depression is accompanied by adenosine triphosphate decreases, increased flux of glucose through the pentose phosphate pathway, free radical production, activation of poly-ADP ribose polymerase via DNA damage, and inhibition of glyceraldehyde dehydrogenase (a key glycolytic enzyme) via depletion of the cytosolic NAD pool. Under these post-brain injury conditions of impaired glycolytic metabolism, glucose becomes a less favorable energy substrate. Ketone bodies are the only known natural alternative substrate to glucose for cerebral energy metabolism. While it has been demonstrated that other fuels (pyruvate, lactate, and acetyl-L-carnitine) can be metabolized by the brain, ketones are the only endogenous fuel that can contribute significantly to cerebral metabolism. Preclinical studies employing both pre- and postinjury implementation of the ketogenic diet have demonstrated improved structural and functional outcome in traumatic brain injury (TBI) models, mild TBI/concussion models, and spinal cord injury. Further clinical studies are required to determine the optimal method to induce cerebral ketone metabolism in the postinjury brain, and to validate the neuroprotective benefits of ketogenic therapy in humans. Copyright © 2014 by the American Society for Biochemistry and Molecular Biology, Inc.

  7. Is there an astrocyte-neuron ketone body shuttle?

    PubMed

    Guzmán, M; Blázquez, C

    2001-01-01

    Ketone bodies can replace glucose as the major source of brain energy when glucose becomes scarce. Although it is generally assumed that the liver supplies extrahepatic tissues with ketone bodies, recent evidence shows that astrocytes are also ketogenic cells. Moreover, the partitioning of fatty acids between ketogenesis and ceramide synthesis de novo might control the survival/death decision of neural cells. These findings support the notion that astrocytes might supply neurons with ketone bodies in situ, and raise the possibility that astrocyte ketogenesis is a cytoprotective pathway.

  8. Substituting Tyr138 in the active site loop of human phenylalanine hydroxylase affects catalysis and substrate activation.

    PubMed

    Leandro, João; Stokka, Anne J; Teigen, Knut; Andersen, Ole A; Flatmark, Torgeir

    2017-07-01

    Mammalian phenylalanine hydroxylase (PAH) is a key enzyme in l-phenylalanine (l-Phe) metabolism and is active as a homotetramer. Biochemical and biophysical work has demonstrated that it cycles between two states with a variably low and a high activity, and that the substrate l-Phe is the key player in this transition. X-ray structures of the catalytic domain have shown mobility of a partially intrinsically disordered Tyr 138 -loop to the active site in the presence of l-Phe. The mechanism by which the loop dynamics are coupled to substrate binding at the active site in tetrameric PAH is not fully understood. We have here conducted functional studies of four Tyr 138 point mutants. A high linear correlation ( r 2 = 0.99) was observed between their effects on the catalytic efficiency of the catalytic domain dimers and the corresponding effect on the catalytic efficiency of substrate-activated full-length tetramers. In the tetramers, a correlation ( r 2 = 0.96) was also observed between the increase in catalytic efficiency (activation) and the global conformational change (surface plasmon resonance signal response) at the same l-Phe concentration. The new data support a similar functional importance of the Tyr 138 -loop in the catalytic domain and the full-length enzyme homotetramer.

  9. Antagonism of stress-induced analgesia by D-phenylalanine, an anti-enkephalinase.

    PubMed

    Bodnar, R J; Lattner, M; Wallace, M M

    1980-12-01

    Methionine- and leucine-enkephalin produce mild and transient analgesic effects, presumably because of enzymatic degradation. Administration of high (250 mg/kg) doses of D-phenylalanine retards the degradation process and elicits analgesia which is reversed by naloxone and which summates with electroacupuncture analgesia. The present study evaluated D-phenylalanine's dose-dependent effects upon a non-opioid analgesic treatment, cold-water swims (CWS), and compared this with morphine. following determination of flinch-jump baselines, three groups of rats received respectively either 25, 50 or 100 mg/kg of D-phenylalanine intraperitoneally in three conditions: alone, with CWS (2 degrees C for 3.5 min), and with morphine (5 mg/kg, SC). Parallel controls with saline were also tested. Simultaneous exposure with each minimally analgesic dose of D-phenylalanine reduced significantly the analgesic, but not hypothermic effects of CWS. By contrast, morphine analgesia was unaffected by D-phenylalanine. These data provide further support that different pain-inhibitory systems mediate CWS and morphine analgesia and suggest that activation of one system is capable of exerting collateral inhibition upon the other.

  10. Mechanism-based site-directed mutagenesis to shift the optimum pH of the phenylalanine ammonia-lyase from Rhodotorula glutinis JN-1.

    PubMed

    Zhu, Longbao; Zhou, Li; Cui, Wenjing; Liu, Zhongmei; Zhou, Zhemin

    2014-09-01

    Phenylalanine ammonia-lyase ( Rg PAL) from Rhodotorula glutinis JN-1 stereoselectively catalyzes the conversion of the l-phenylalanine into trans -cinnamic acid and ammonia, and was used in chiral resolution of dl-phenylalanine to produce the d-phenylalanine under acidic condition. However, the optimum pH of Rg PAL is 9 and the Rg PAL exhibits low catalytic efficiency at acidic side. Therefore, a mutant Rg PAL with a lower optimum pH is expected. Based on catalytic mechanism and structure analysis, we constructed a mutant Rg PAL-Q137E by site-directed mutagenesis, and found that this mutant had an extended optimum pH 7-9 with activity of 1.8-fold higher than that of the wild type at pH 7. As revealed by Friedel-Crafts-type mechanism of Rg PAL, the improvement of the Rg PAL-Q137E might be due to the negative charge of Glu137 which could stabilize the intermediate transition states through electrostatic interaction. The Rg PAL-Q137E mutant was used to resolve the racemic dl-phenylalanine, and the conversion rate and the ee D value of d-phenylalanine using Rg PAL-Q137E at pH 7 were increased by 29% and 48%, and achieved 93% and 86%, respectively. This work provides an effective strategy to shift the optimum pH which is favorable to further applications of Rg PAL.

  11. Synthesis and degradation of phenylalanine ammonia-lyase of Rhodosporidium toruloides.

    PubMed Central

    Gilbert, H J; Tully, M

    1982-01-01

    The regulation of the enzyme phenylalanine ammonia-lyase (PAL), which is of potential use in oral treatment of phenylketonuria, was investigated. Antiserum against PAL was prepared and was shown to be monospecific for the enzyme by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The native enzyme and two inactive mutant forms of the enzyme were purified to homogeneity by immunoaffinity chromatography, using anti-PAL immunoglobulin G-Sepharose 4B. Both mutant enzymes contained intact prosthetic groups. The formation of PAL catalytic activity after phenylalanine was added to yeast cultures was paralleled by the appearance of enzyme antigen. During induction, uptake of [3H]leucine into the enzyme was higher than uptake into total protein. Our results are consistent with de novo synthesis of an enzyme induced by phenylalanine, rather than activation of a proenzyme. The half-lives of PAL and total protein were similar in both exponential and stationary phase cultures. No metabolite tested affected the rate of enzyme degradation. Glucose repressed enzyme synthesis, whereas ammonia reduced phenylalanine uptake and pool size and so may repress enzyme synthesis through inducer exclusion. The synthesis of enzyme antigen by a mutant unable to metabolize phenylalanine indicated that this amino acid is the physiological inducer of the enzyme. PMID:7068528

  12. Synthesis and degradation of phenylalanine ammonia-lyase of Rhodosporidium toruloides.

    PubMed

    Gilbert, H J; Tully, M

    1982-05-01

    The regulation of the enzyme phenylalanine ammonia-lyase (PAL), which is of potential use in oral treatment of phenylketonuria, was investigated. Antiserum against PAL was prepared and was shown to be monospecific for the enzyme by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The native enzyme and two inactive mutant forms of the enzyme were purified to homogeneity by immunoaffinity chromatography, using anti-PAL immunoglobulin G-Sepharose 4B. Both mutant enzymes contained intact prosthetic groups. The formation of PAL catalytic activity after phenylalanine was added to yeast cultures was paralleled by the appearance of enzyme antigen. During induction, uptake of [3H]leucine into the enzyme was higher than uptake into total protein. Our results are consistent with de novo synthesis of an enzyme induced by phenylalanine, rather than activation of a proenzyme. The half-lives of PAL and total protein were similar in both exponential and stationary phase cultures. No metabolite tested affected the rate of enzyme degradation. Glucose repressed enzyme synthesis, whereas ammonia reduced phenylalanine uptake and pool size and so may repress enzyme synthesis through inducer exclusion. The synthesis of enzyme antigen by a mutant unable to metabolize phenylalanine indicated that this amino acid is the physiological inducer of the enzyme.

  13. Special feature of kinetics of ZcE isomerization of β-N-methylaminovinyl trifluoromethyl ketone in Ar matrix exposed to UV radiation and spontaneous E ⇌ Z isomerization of α-methyl-β-N-methylaminovinyl trifluoromethyl ketone

    NASA Astrophysics Data System (ADS)

    Vdovenko, Sergey I.; Gerus, Igor I.; Pagacz-Kostrzewa, Magdalena; Wierzejewska, Maria; Zhuk, Yuri I.; Kukhar, Valery P.

    2018-06-01

    Although it is well known that reactivity of α,β-unsaturated enaminoketones is closely associated with spatial and electronic structure but until now little attention was devoted to quantitative investigation of interconversion of different stereoisomeric forms of enaminoketones. In present work we studied peculiarities of kinetics of Z ⇌ E isomerization of enaminoketone 4-(N-methylamino)-1,1,1-trifluorobut-3-en-2-one F3C-COsbnd CHdbnd CHsbnd NH(CH3) (1) in Ar-matrix exposed to UV-radiation (λ = 340 nm) with IR Fourier and 2D correlation spectroscopy and we found that Z-s-Z-s-trans isomer transforms primarily into two E-isomers, E-s-E-s-trans and E-s-Z-s-trans which further turn into the E-s-E-s-cis and E-s-Z-s-cis conformers all interconversion rate constants being comparable in magnitude. Along with this process long-term exposure to the UV-radiation results in proton transfer from nitrogen of methylamino group to carbonyl oxygen with simultaneous isomerization of 'cyclic' iminoenol form into 'linear'one. In solution of enaminoketone 4-(N-methylamino)-1,1,1-trifluoro-3-methylbut-3-en-2-one F3C-CO-C(CH3)dbnd CH-NH(CH3) (2) we observed reversed process, namely, spontaneous interconversion of the E-s-E-s-trans and E-s-Z-s-trans conformers into the Z-s-Z-trans isomer. It was found that rate constants of the dimeric forms of the E-s-E-s-trans and E-s-Z-s-trans conformers are higher than those of the monomers and are independent on total enaminoketone concentration. Addition of highly polar HMPA promotes proton transfer from nitrogen to oxygen in the Z-s-Z-s-trans isomer of 2 with subsequent isomerization into the linear imino-enol product but the rate constant of this transformation is ten-fold smaller than that for 1 in the Ar matrix exposed to UV radiation. Special feature of kinetics of Z ⇌ E isomerization of β-N-methylaminovinyl trifluoromethyl ketone in Ar matrix exposed to UV radiation and spontaneous E ⇌ Z isomerization of α-Methyl-, β-N

  14. Ketones Prevent Oxidative Impairment of Hippocampal Synaptic Integrity through KATP Channels

    PubMed Central

    Kim, Do Young; Abdelwahab, Mohammed G.; Lee, Soo Han; O’Neill, Derek; Thompson, Roger J.; Duff, Henry J.; Sullivan, Patrick G.; Rho, Jong M.

    2015-01-01

    Dietary and metabolic therapies are increasingly being considered for a variety of neurological disorders, based in part on growing evidence for the neuroprotective properties of the ketogenic diet (KD) and ketones. Earlier, we demonstrated that ketones afford hippocampal synaptic protection against exogenous oxidative stress, but the mechanisms underlying these actions remain unclear. Recent studies have shown that ketones may modulate neuronal firing through interactions with ATP-sensitive potassium (KATP) channels. Here, we used a combination of electrophysiological, pharmacological, and biochemical assays to determine whether hippocampal synaptic protection by ketones is a consequence of KATP channel activation. Ketones dose-dependently reversed oxidative impairment of hippocampal synaptic integrity, neuronal viability, and bioenergetic capacity, and this action was mirrored by the KATP channel activator diazoxide. Inhibition of KATP channels reversed ketone-evoked hippocampal protection, and genetic ablation of the inwardly rectifying K+ channel subunit Kir6.2, a critical component of KATP channels, partially negated the synaptic protection afforded by ketones. This partial protection was completely reversed by co-application of the KATP blocker, 5-hydoxydecanoate (5HD). We conclude that, under conditions of oxidative injury, ketones induce synaptic protection in part through activation of KATP channels. PMID:25848768

  15. The “Gate Keeper” Role of Trp222 Determines the Enantiopreference of Diketoreductase toward 2-Chloro-1-Phenylethanone

    PubMed Central

    Lu, Zhuo; Liu, Nan; Chen, Yijun

    2014-01-01

    Trp222 of diketoreductase (DKR), an enzyme responsible for reducing a variety of ketones to chiral alcohols, is located at the hydrophobic dimeric interface of the C-terminus. Single substitutions at DKR Trp222 with either canonical (Val, Leu, Met, Phe and Tyr) or unnatural amino acids (UAAs) (4-cyano-L-phenylalanine, 4-methoxy-L-phenylalanine, 4-phenyl-L-phenyalanine, O-tert-butyl-L-tyrosine) inverts the enantiotope preference of the enzyme toward 2-chloro-1-phenylethanone with close side chain correlation. Analyses of enzyme activity, substrate affinity and ternary structure of the mutants revealed that substitution at Trp222 causes a notable change in the overall enzyme structure, and specifically in the entrance tunnel to the active center. The size of residue 222 in DKR is vital to its enantiotope preference. Trp222 serves as a “gate keeper” to control the direction of substrate entry into the active center. Consequently, opposite substrate-binding orientations produce respective alcohol enantiomers. PMID:25072248

  16. Stability of proton-bound clusters of alkyl alcohols, aldehydes and ketones in Ion Mobility Spectrometry.

    PubMed

    Jurado-Campos, Natividad; Garrido-Delgado, Rocío; Martínez-Haya, Bruno; Eiceman, Gary A; Arce, Lourdes

    2018-08-01

    Significant substances in emerging applications of ion mobility spectrometry such as breath analysis for clinical diagnostics and headspace analysis for food purity include low molar mass alcohols, ketones, aldehydes and esters which produce mobility spectra containing protonated monomers and proton-bound dimers. Spectra for all n- alcohols, aldehydes and ketones from carbon number three to eight exhibited protonated monomers and proton-bound dimers with ion drift times of 6.5-13.3 ms at ambient pressure and from 35° to 80 °C in nitrogen. Only n-alcohols from 1-pentanol to 1-octanol produced proton-bound trimers which were sufficiently stable to be observed at these temperatures and drift times of 12.8-16.3 ms. Polar functional groups were protected in compact structures in ab initio models for proton-bound dimers of alcohols, ketones and aldehydes. Only alcohols formed a V-shaped arrangement for proton-bound trimers strengthening ion stability and lifetime. In contrast, models for proton-bound trimers of aldehydes and ketones showed association of the third neutral through weak, non-specific, long-range interactions consistent with ion dissociation in the ion mobility drift tube before arriving at the detector. Collision cross sections derived from reduced mobility coefficients in nitrogen gas atmosphere support the predicted ion structures and approximate degrees of hydration. Copyright © 2018 Elsevier B.V. All rights reserved.

  17. Relationships between phenylalanine levels, intelligence and socioeconomic status of patients with phenylketonuria.

    PubMed

    Castro, Isabel Pimenta Spínola; Borges, Juliana Martins; Chagas, Heloísa Alves; Tibúrcio, Jacqueline; Starling, Ana Lúcia Pimenta; Aguiar, Marcos José Burle de

    2012-07-01

    To assess intelligence and its relationship with blood phenylalanine concentrations and socioeconomic status in patients with phenylketonuria after 6 to 12 years of treatment. Sixty-three children were classified according to phenylalanine levels and socioeconomic status and assessed using the Wechsler Intelligence Scale for Children. The Statistical Package for the Social Sciences (SPSS) was used to analyze phenylalanine; ANOVA was used to analyze intelligence quotients (IQ) and phenylalanine levels; and ordinal logistic regression was used to analyze the likelihood of higher IQ. The overall IQ scores of 90.5% of the children were within a range from borderline intellectual deficiency to very high intelligence; for verbal IQ this proportion was 96.8% and 92.1% had performance IQ scores within this band. The categories from low to upper-medium socioeconomic status contained 98.4% of patients' families. The likelihood of having medium to high IQ was 4.29 times greater for children with good phenylalanine control and 4.03 greater for those from higher socioeconomic strata. Treatment prevented mental retardation in 90.5% of the patients. Control of phenylalanine levels and higher socioeconomic status were associated with higher IQ scores.

  18. General and mild Ni(0)-catalyzed α-arylation of ketones using aryl chlorides.

    PubMed

    Fernández-Salas, José A; Marelli, Enrico; Cordes, David B; Slawin, Alexandra M Z; Nolan, Steven P

    2015-03-02

    A general methodology for the α-arylation of ketones using a nickel catalyst has been developed. The new well-defined [Ni(IPr*)(cin)Cl] (1 c) pre-catalyst showed great efficiency for this transformation, allowing the coupling of a wide range of ketones, including acetophenone derivatives, with various functionalised aryl chlorides. This cinnamyl-based Ni-N-heterocyclic carbene (NHC) complex has demonstrated a different behaviour to previously reported NHC-Ni catalysts. Preliminary mechanistic studies suggest a Ni(0)/Ni(II) catalytic cycle to be at play. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Determination of Phenylalanine and Tyrosine by High Performance Liquid Chromatography-Tandem Mass Spectrometry.

    PubMed

    Peat, Judy; Garg, Uttam

    2016-01-01

    Hyperphenylalaninemia/phenylketonuria (PKU) is one of the most common inborn errors of amino acid metabolism affecting about 1:15,000 infants in the United States. PKU is an autosomal recessive disorder that if untreated results in mental retardation. The most common cause of PKU is deficiency of the enzyme phenylalanine hydroxylase that converts phenylalanine to tyrosine. Tyrosine deficiency results in impaired synthesis of catecholamines and thyroxine. Less commonly, it can result from defects in the synthesis or regeneration of tetrahydrobiopterin (BH4), an essential cofactor for the enzyme phenylalanine hydroxylase. Increased phenylalanine and decreased tyrosine in blood are used in the diagnosis and follow-up of patients with PKU. LC/MS/MS method is described for the quantification of phenylalanine and tyrosine.

  20. Combined n-benzoyl-d-phenylalanine and metformin treatment reverses changes in the fatty acid composition of streptozotocin diabetic rats.

    PubMed

    Kumar, Natarajan Ashok; Pari, Leelavinothan

    2006-01-01

    The present investigation was carried out to evaluate the effect of N-benzoyl-D-phenylalanine (NBDP) and metformin on blood glucose, plasma insulin, and on the fatty acid composition of total lipids in the livers and kidneys of control and experimental diabetic rats. When compared with nondiabetic control rats, neonatal streptozotocin (nSTZ) diabetic rats showed a significant increase in blood glucose and decreased plasma insulin. Analysis of fatty acids revealed a significant increase in the concentration of palmitic, stearic, and oleic acids in liver and kidney, whereas linolenic and arachidonic acids were significantly decreased. In diabetic rats, the oral administration of combined NBDP/metformin for 6 wk decreased the high concentrations of palmitic, stearic, and oleic acids and elevated the low levels of linolenic and arachidonic acids. The results suggest that the NBDP/metformin combination exhibits both antidiabetic and antihyperlipidemic effects in nSTZ diabetic rats and prevents the fatty acid changes produced during diabetes.

  1. Synthesis of 1,4-amino alcohols by Grignard reagent addition to THF and N-tosyliminobenzyliodinane.

    PubMed

    Tejo, Ciputra; See, Yang Feng Anders; Mathiew, Mitch; Chan, Philip Wai Hong

    2016-01-21

    The synthesis of 1,4-amino alcohols from THF treated with N-tosyliminobenzyliodinane (PhINTs) followed by a Grignard reagent under mild reaction conditions at room temperature is described herein. Various Grignard reagents were shown to be compatible, furnishing the corresponding 4-substituted-N-1,4-tosylamino alcohols in good to excellent yields. A partial or full detosylation of the N-tosyl-1,4-amino alcohol was observed in instances involving a sterically bulky Grignard reagent, leading to the deprotected 1,4-amino alcohol product in moderate to good yields. The synthetic utility of this protocol was demonstrated by the synthesis of a 5-substituted-N-tosyl-1,5-amino alcohol from THP and the conversion of two examples to their corresponding γ-lactam and pyrrolidine adducts.

  2. [[111In]-DTPA-D-phenylalanine octreotide SPECT for the scintigraphic imaging of enhanced somatostatin-receptor density in endocrine ophthalmopathy].

    PubMed

    Cordes, M; Hosten, N; Gräf, K J; Wenzel, K W; Venz, S; Keske, U; Eichstädt, H; Felix, R

    1994-01-01

    Recently, [111In]-DTPA-D-phenylalanine-octreotide was introduced for clinical use. This radioligand binds specifically to somatostatin receptors and is suitable for SPECT examinations. The aim of this study was to clarify whether an increased somatostatin receptor density can be imaged and quantified in patients with endocrine ophthalmopathy (e.o.). 7 patients between 34 and 55 years with e.o. at stages III to VI and 4 controls between 38 and 63 years were examined. All patients and controls received approximately 200 MBq [111In]-DTPA-D-phenylalanine-octreotide by IV injection. A SPECT examination was performed 4 hours after injection and a normalised tracer uptake (A(n)) was calculated for both orbitae. In patients with e.o. the values of A(n) were significantly higher compared with controls (P = 0.002). There was a correlation between A(n) and exophthalmus stages according to Hertel with r = 0.844 (P = 0.001). These results indicate that [111In]-DTPA-D-phenylalanine-octreotide SPECT might be useful for the in vivo assessment of an increased somatostatin receptor density in e.o. These findings could have an impact on the treatment with somatostatin analogous in e.o.

  3. Radiolysis of N-acetyl amino acids as model compounds for radiation degradation of polypeptides

    NASA Astrophysics Data System (ADS)

    Wayne Garrett, R.; Hill, David J. T.; Ho, Sook-Ying; O'Donnell, James H.; O'Sullivan, Paul W.; Pomery, Peter J.

    Radiation chemical yields of (i) the volatile radiolysis products and (ii) the trapped free radicals from the y-radiolysis of the N-acetyl derivatives of glycine, L-valine, L-phenylalanine and L-tyrosine in the polycrystalline state have been determined at room temperature (303 K). Carbon dioxide was found to be the major molecular product for all these compounds with G(CO 2) varying from 0.36 for N-acetyl-L-tyrosine to 8 for N-acetyl-L-valine. There was evidence for some scission of the N-C α bond, indicated by the production of acetamide and the corresponding aliphatic acid, but the determination reaction was found to be of much lesser importance than the decarboxylation reaction. A protective effect of the aromatic ring in N-acetyl-L-phenylalanine and in N-acetyl-L-tyrosine was indicated by the lower yields of volatile products for these compounds. The yields of trapped free radicals were found to vary with the nature of the amino acid side chain, increasing with chain length and chain branching. The radical yields were decreased by incorporation of an aromatic moiety in the side chain, this effect being greater for the tyrosyl side chain than for the phenyl side chain. The G(R·) values showed a good correlation with G(CO 2) indicating that a common reaction may be involved in radical production and carbon dioxide formation.

  4. The synthesis of [14 C]4-acetylphenylalanine, effect on cell viability, and assessment of protein incorporation in male rat hepatocytes.

    PubMed

    Maxwell, Brad D; Ly, Van; Brock, Barry; Dodge, Robert; Tirmenstein, Mark; Calvano, Jacqueline

    2017-06-30

    PEGylation is a proven approach to prolonging the duration of action and enhancing biophysical solubility and stability of peptides. 4-Acetylphenylalanine is a novel amino acid with a ketone side chain that is uniquely reactive in proteins. The ketone functionality can react with an aminooxy functionalized polyethyleneglycol polymer to form a stable oxime adduct of the protein. One concern with using unnatural amino acids, such as 4-acetylphenylalanine, is the possibility of it being cleaved from the peptide and becoming incorporated into endogenous proteins. To determine whether this occurs, an in vitro experiment to assess the cell viability and amino acid incorporation into endogenous proteins using primary male rat hepatocytes in the presence of [ 14 C]4-acetylphenylalanine, 4 or [ 14 C(U)]L-phenylalanine was conducted. [ 14 C]4-acetylphenylalanine, 4 was prepared in 2 radiochemical steps from [1- 14 C]acetyl chloride in an overall 8% radiochemical yield and in 99.9% radiochemical purity. The results showed that there was no evidence of carbon-14 incorporation into hepatocyte endogenous proteins with [ 14 C]pAcF and there was no difference between it and L-phenylalanine in cell viability assessments at any of the concentrations studied between 0.1 and 1000 μM. Copyright © 2017 John Wiley & Sons, Ltd.

  5. Optimisation of trans-cinnamic acid and hydrocinnamyl alcohol production with recombinant Saccharomyces cerevisiae and identification of cinnamyl methyl ketone as a by-product.

    PubMed

    Gottardi, Manuela; Grün, Peter; Bode, Helge B; Hoffmann, Thomas; Schwab, Wilfried; Oreb, Mislav; Boles, Eckhard

    2017-12-01

    Trans-cinnamic acid (tCA) and hydrocinnamyl alcohol (HcinOH) are valuable aromatic compounds with applications in the flavour, fragrance and cosmetic industry. They can be produced with recombinant yeasts from sugars via phenylalanine after expression of a phenylalanine ammonia lyase (PAL) and an aryl carboxylic acid reductase. Here, we show that in Saccharomyces cerevisiae a PAL enzyme from the bacterium Photorhabdus luminescens was superior to a previously used plant PAL enzyme for the production of tCA. Moreover, after expression of a UDP-glucose:cinnamate glucosyltransferase (FaGT2) from Fragaria x ananassa, tCA could be converted to cinnamoyl-D-glucose which is expected to be less toxic to the yeast cells. Production of tCA and HcinOH from glucose could be increased by eliminating feedback-regulated steps of aromatic amino acid biosynthesis and diminishing the decarboxylation step of the competing Ehrlich pathway. Finally, an unknown by-product resulting from further metabolisation of a carboligation product of cinnamaldehyde (cinALD) with activated acetaldehyde, mediated by pyruvate decarboxylases, could be identified as cinnamyl methyl ketone providing a new route for the biosynthesis of precursors, such as (2S,3R) 5-phenylpent-4-ene-2,3-diol, necessary for the chemical synthesis of specific biologically active drugs such as daunomycin. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  6. 30 CFR 57.5006 - Air Quality-Surface Only [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... acceptable to the Secretary. (a) Carbon tetrachloride, (b) Phenol, (c) 4-Nitrobiphenyl, (d) Alpha..., (h) Bis (chloromethyl) ether, (i) Beta-napthylamine, (j) Benzidine, (k) 4-Aminodiphenyl, (l) Ethyleneimine, (m) Beta-propiolactone, (n) 2-Acetylaminofluorene, (o) 4-Dimethylaminobenzene, and (p) N...

  7. 30 CFR 57.5006 - Air Quality-Surface Only [Reserved

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... acceptable to the Secretary. (a) Carbon tetrachloride, (b) Phenol, (c) 4-Nitrobiphenyl, (d) Alpha..., (h) Bis (chloromethyl) ether, (i) Beta-napthylamine, (j) Benzidine, (k) 4-Aminodiphenyl, (l) Ethyleneimine, (m) Beta-propiolactone, (n) 2-Acetylaminofluorene, (o) 4-Dimethylaminobenzene, and (p) N...

  8. One-Pot Synthesis of D-Phenylalanine-Functionalized Multi-Walled Carbon Nanotubes: a Metal-Free Chiral Material for the Asymmetric Electroreduction of Aromatic Ketones.

    PubMed

    Yue, Ying-Na; Zeng, Sheng; Wang, Hui; Wang, Shuo; Wang, Huan; Lu, Jia-Xing

    2018-06-19

    A simple protocol to synthesize D-phenylalanine (D-PHE)-functionalized multi-walled carbon nanotubes (MWCNTs) via one-pot method was established by grafting D-PHE onto MWCNTs to obtain D-PHE-MWCNTs under mild reaction conditions. The resulting D-PHE-MWCNTs were detailedly characterized via spectroscopy and surface analysis. The electroreduction of 2,2,2-trifluoroacetophenone at D-PHE-MWCNTs cathode afforded (S)-α-(trifluoromethyl) benzyl alcohol whose yield was 65% and the enantiomeric excess was 40%. No extra catalysts were required in this electrochemical reaction solution compared with other reactions requiring homogeneous catalysis. The metal-free chiral material also showed acceptable asymmetric electroreduction performance, considerable stability and favorable reusability.

  9. The thermodynamic parameters of the step dissociation of L-phenylalanyl in aqueous solution

    NASA Astrophysics Data System (ADS)

    Kochergina, L. A.; Emel'Yanov, A. V.; Krutova, O. N.; Gorboletova, G. G.

    2007-10-01

    The heats of interaction of L-phenylalanine with solutions of nitric acid and potassium and lithium hydroxides were determined calorimetrically at 288.15, 298.15, and 308.15 K and solution ionic strengths of 0.5, 0.75, and 1.0 in the presence of LiNO3 and KNO3. The standard thermodynamic characteristics (Δr H°, Δr G°, Δr S°, and Δ C {/p °} of acid-base interactions in aqueous solutions of L-phenylalanine were calculated. The influence of the concentration of background electrolytes and temperature on the heats of dissociation of L-phenylalanine was considered. A comparative analysis of the standard thermodynamic characteristics of step dissociation of L-phenylalanine and alanine was performed in terms of the modern concepts of the structure and physicochemical properties of these compounds and their solutions.

  10. A Membrane-Bound NAC Transcription Factor, ANAC017, Mediates Mitochondrial Retrograde Signaling in Arabidopsis[W][OPEN

    PubMed Central

    Ng, Sophia; Ivanova, Aneta; Duncan, Owen; Law, Simon R.; Van Aken, Olivier; De Clercq, Inge; Wang, Yan; Carrie, Chris; Xu, Lin; Kmiec, Beata; Walker, Hayden; Van Breusegem, Frank; Whelan, James; Giraud, Estelle

    2013-01-01

    Plants require daily coordinated regulation of energy metabolism for optimal growth and survival and therefore need to integrate cellular responses with both mitochondrial and plastid retrograde signaling. Using a forward genetic screen to characterize regulators of alternative oxidase1a (rao) mutants, we identified RAO2/Arabidopsis NAC domain-containing protein17 (ANAC017) as a direct positive regulator of AOX1a. RAO2/ANAC017 is targeted to connections and junctions in the endoplasmic reticulum (ER) and F-actin via a C-terminal transmembrane (TM) domain. A consensus rhomboid protease cleavage site is present in ANAC017 just prior to the predicted TM domain. Furthermore, addition of the rhomboid protease inhibitor N-p-Tosyl-l-Phe chloromethyl abolishes the induction of AOX1a upon antimycin A treatment. Simultaneous fluorescent tagging of ANAC017 with N-terminal red fluorescent protein (RFP) and C-terminal green fluorescent protein (GFP) revealed that the N-terminal RFP domain migrated into the nucleus, while the C-terminal GFP tag remained in the ER. Genome-wide analysis of the transcriptional network regulated by RAO2/ANAC017 under stress treatment revealed that RAO2/ANAC017 function was necessary for >85% of the changes observed as a primary response to cytosolic hydrogen peroxide (H2O2), but only ∼33% of transcriptional changes observed in response to antimycin A treatment. Plants with mutated rao2/anac017 were more stress sensitive, whereas a gain-of-function mutation resulted in plants that had lower cellular levels of H2O2 under untreated conditions. PMID:24045017

  11. Design, synthesis, and molecular docking studies of N-(9,10-anthraquinone-2-carbonyl)amino acid derivatives as xanthine oxidase inhibitors.

    PubMed

    Zhang, Ting-Jian; Li, Song-Ye; Yuan, Wei-Yan; Zhang, Yi; Meng, Fan-Hao

    2018-04-01

    A series of N-(9,10-anthraquinone-2-carbonyl)amino acid derivatives (1a-j) was designed and synthesized as novel xanthine oxidase inhibitors. Among them, the L/D-phenylalanine derivatives (1d and 1i) and the L/D-tryptophan derivatives (1e and 1j) were effective with micromolar level potency. In particular, the L-phenylalanine derivative 1d (IC 50  = 3.0 μm) and the D-phenylalanine derivative 1i (IC 50  = 2.9 μm) presented the highest potency and were both more potent than the positive control allopurinol (IC 50  = 8.1 μm). Preliminary SAR analysis pointed that an aromatic amino acid fragment, for example, phenylalanine or tryptophan, was essential for the inhibition; the D-amino acid derivative presented equal or greater potency compared to its L-enantiomer; and the 9,10-anthraquinone moiety was welcome for the inhibition. Molecular simulations provided rational binding models for compounds 1d and 1i in the xanthine oxidase active pocket. As a result, compounds 1d and 1i could be promising lead compounds for further investigation. © 2017 John Wiley & Sons A/S.

  12. 21 CFR 862.1435 - Ketones (nonquantitative) test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry Test...) test system is a device intended to identify ketones in urine and other body fluids. Identification of... acidity of body fluids) or ketosis (a condition characterized by increased production of ketone bodies...

  13. 21 CFR 862.1435 - Ketones (nonquantitative) test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry Test...) test system is a device intended to identify ketones in urine and other body fluids. Identification of... acidity of body fluids) or ketosis (a condition characterized by increased production of ketone bodies...

  14. 21 CFR 862.1435 - Ketones (nonquantitative) test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry Test...) test system is a device intended to identify ketones in urine and other body fluids. Identification of... acidity of body fluids) or ketosis (a condition characterized by increased production of ketone bodies...

  15. Identification and characterization of CYP79D16 and CYP71AN24 catalyzing the first and second steps in L-phenylalanine-derived cyanogenic glycoside biosynthesis in the Japanese apricot, Prunus mume Sieb. et Zucc.

    PubMed

    Yamaguchi, Takuya; Yamamoto, Kazunori; Asano, Yasuhisa

    2014-09-01

    Japanese apricot, Prunus mume Sieb. et Zucc., belonging to the Rosaceae family, produces as defensive agents the cyanogenic glycosides prunasin and amygdalin, which are presumably derived from L-phenylalanine. In this study, we identified and characterized cytochrome P450s catalyzing the conversion of L-phenylalanine into mandelonitrile via phenylacetaldoxime. Full-length cDNAs encoding CYP79D16, CYP79A68, CYP71AN24, CYP71AP13, CYP71AU50, and CYP736A117 were cloned from P. mume ‘Nanko’ using publicly available P. mume RNA-sequencing data, followed by 5′- and 3′-RACE. CYP79D16 was expressed in seedlings, whereas CYP71AN24 was expressed in seedlings and leaves. Enzyme activity of these cytochrome P450s expressed in Saccharomyces cerevisiae was evaluated by liquid and gas chromatography–mass spectrometry. CYP79D16, but not CYP79A68, catalyzed the conversion of L-phenylalanine into phenylacetaldoxime. CYP79D16 showed no activity toward other amino acids. CYP71AN24, but not CYP71AP13, CYP71AU50, and CYP736A117, catalyzed the conversion of phenylacetaldoxime into mandelonitrile. CYP71AN24 also showed lower conversions of various aromatic aldoximes and nitriles. The K m value and turnover rate of CYP71AN24 for phenylacetaldoxime were 3.9 µM and 46.3 min(−1), respectively. The K m value and turnover of CYP71AN24 may cause the efficient metabolism of phenylacetaldoxime, avoiding the release of the toxic intermediate to the cytosol. These results suggest that cyanogenic glycoside biosynthesis in P. mume is regulated in concert with catalysis by CYP79D16 in the parental and sequential reaction of CYP71AN24 in the seedling.

  16. IR + VUV double resonance spectroscopy and extended density functional theory studies of ketone solvation by alcohol: 2-butanone·(methanol)n, n = 1-4 clusters.

    PubMed

    Shin, Joong-Won; Bernstein, Elliot R

    2017-09-28

    Infrared plus vacuum ultraviolet (IR + VUV) photoionization vibrational spectroscopy of 2-butanone/methanol clusters [MEK·(MeOH) n , n = 1-4] is performed to explore structures associated with hydrogen bonding of MeOH molecules to the carbonyl functional group of the ketone. IR spectra and X3LYP/6-31++G(d,p) calculations show that multiple isomers of MEK·(MeOH) n are generated in the molecular beam as a result of several hydrogen bonding sites available to the clusters throughout the size range investigated. Isomer interconversion involving solvating MeOH rearrangement should probably occur for n = 1 and 2. The mode energy for a hydrogen bonded OH stretching transition gradually redshifts as the cluster size increases. Calculations suggest that the n = 3 cluster isomers adopt structures in which the MEK molecule is inserted into the cyclic MeOH hydrogen bond network. In larger structures, the cyclic network may be preserved.

  17. Dl-phenylalanine in depressed patients: an open study.

    PubMed

    Beckmann, H; Strauss, M A; Ludolph, E

    1977-01-01

    In an open study dl-phenylalanine in doses from 75-200 mg/day was administered to 20 depressed patients for 20 days. Patients were classified according to the International Classification of Diseases (ICD). The AMP system, the Hamilton depression scale and the von Zerssen self rating questionnaire were used for documentation of psychopathological, neurologic and somatic changes. In addition a global clinical impression was agreed upon by experienced psychiatrists. At the end of the trial 12 patients (8 with complete, 4 with good response) could be discharged without any further treatment. 4 patients with partially untypical depressions experienced mild to moderate responses, whereas 4 patients did not respond at all to the phenylalanine administration. Depressive "core symptoms" as depressed mood, retardation and/or agitation were preferentially, anxiety and sleep disturbances moderately and hypochondriasis and compulsiveness were not influenced. It is concluded that dl-phenylalanine might have substantial antidepressant properties and that further more controlled investigations are warranted.

  18. Production of methyl-vinyl ketone from levulinic acid

    DOEpatents

    Dumesic, James A [Verona, WI; West,; Ryan, M [Madison, WI

    2011-06-14

    A method for converting levulinic acid to methyl vinyl ketone is described. The method includes the steps of reacting an aqueous solution of levulinic acid, over an acid catalyst, at a temperature of from room temperature to about 1100 K. Methyl vinyl ketone is thereby formed.

  19. Tricaprylin Alone Increases Plasma Ketone Response More Than Coconut Oil or Other Medium-Chain Triglycerides: An Acute Crossover Study in Healthy Adults

    PubMed Central

    Vandenberghe, Camille; St-Pierre, Valérie; Pierotti, Tyler; Fortier, Mélanie; Castellano, Christian-Alexandre; Cunnane, Stephen C

    2017-01-01

    Abstract Background: Ketones are the brain's main alternative fuel to glucose. Dietary medium-chain triglyceride (MCT) supplements increase plasma ketones, but their ketogenic efficacy relative to coconut oil (CO) is not clear. Objective: The aim was to compare the acute ketogenic effects of the following test oils in healthy adults: coconut oil [CO; 3% tricaprylin (C8), 5% tricaprin (C10)], classical MCT oil (C8-C10; 55% C8, 35% C10), C8 (>95% C8), C10 (>95% C10), or CO mixed 50:50 with C8-C10 or C8. Methods: In a crossover design, 9 participants with mean ± SD ages 34 ± 12 y received two 20-mL doses of the test oils prepared as an emulsion in 250 mL lactose-free skim milk. During the control (CTL) test, participants received only the milk vehicle. The first test dose was taken with breakfast and the second was taken at noon but without lunch. Blood was sampled every 30 min over 8 h for plasma acetoacetate and β-hydroxybutyrate (β-HB) analysis. Results: C8 was the most ketogenic test oil with a day-long mean ± SEM of +295 ± 155 µmol/L above the CTL. C8 alone induced the highest plasma ketones expressed as the areas under the curve (AUCs) for 0–4 and 4–8 h (780 ± 426 µmol ⋅ h/L and 1876 ± 772 µmol ⋅ h/L, respectively); these values were 813% and 870% higher than CTL values (P < 0.01). CO plasma ketones peaked at +200 µmol/L, or 25% of the C8 ketone peak. The acetoacetate-to-β-HB ratio increased 56% more after CO than after C8 after both doses. Conclusions: In healthy adults, C8 alone had the highest net ketogenic effect over 8 h, but induced only half the increase in the acetoacetate-to-β-HB ratio compared with CO. Optimizing the type of MCT may help in developing ketogenic supplements designed to counteract deteriorating brain glucose uptake associated with aging. This trial was registered at clinicaltrials.gov as NCT 02679222.

  20. Fuel cell performance of pendent methylphenyl sulfonated poly(ether ether ketone ketone)s

    NASA Astrophysics Data System (ADS)

    Zhang, Hanyu; Stanis, Ronald J.; Song, Yang; Hu, Wei; Cornelius, Chris J.; Shi, Qiang; Liu, Baijun; Guiver, Michael D.

    2017-11-01

    Meta- and para-linked homopolymers bearing 3-methylphenyl (Me) pendent groups were postsulfonated to create sulfonated poly(ether ether ketone ketone) (SPEEKK) backbone isomers, which are referred to as Me-p-SPEEKK and Me-m-SPEEKK. Their thermal and oxidative stability, mechanical properties, dimensional stability, methanol permeability, and proton conductivity are characterized. Me-p-SPEEKK and Me-m-SPEEKK proton conductivities at 100 °C are 116 and 173 mS cm-1, respectively. Their methanol permeabilities are 3.3-3.9 × 10-7 cm2 s-1, and dimensional swelling at 100 °C is 16.4-17.5%. Me-p-SPEEKK and Me-m-SPEEKK were fabricated into membrane electrode assemblies (MEAs), and electrochemical properties were evaluated within a direct methanol fuel cell (DMFC) and proton-exchange membrane fuel cell (PEMFC). When O2 is used as the oxidant at 80 °C and 100% RH, the maximum power density of Me-m-SPEEKK reaches 657 mW cm-2, which is higher than those of Nafion 115 (552 mW cm-2). DMFC performance is 85 mW cm-2 at 80 °C with 2.0 M methanol using Me-p-SPEEKK due to its low MeOH crossover. In general, these electrochemical results are comparable to Nafion. These ionomer properties, combined with a potentially less expensive and scalable polymer manufacturing process, may broaden their potential for many practical applications.

  1. Simple 3,4-Dihydroxy-L-Phenylalanine Surface Modification Enhances Titanium Implant Osseointegration in Ovariectomized Rats.

    PubMed

    Ma, Ting; Ge, Xi-Yuan; Hao, Ke-Yi; Zhang, Bi-Ru; Jiang, Xi; Lin, Ye; Zhang, Yu

    2017-12-19

    Osteoporosis presents a challenge to the long-term success of osseointegration of endosseous implants. The bio-inspired 3,4-dihydroxy-L-phenylalanine (Dopa) coating is widely used as a basic layer to bind osteogenetic molecules that may improve osseointegration. To date, little attention has focused on application of Dopa alone or binding inhibitors of bone resorption in osteoporosis. Local use of a bisphosphonate such as zoledronic acid (ZA), an inhibitor of osteoclast-mediated bone resorption, has been proven to improve implant osseointegration. In this study, ovariectomized rats were divided into four groups and implanted with implants with different surface modifications: sandblasted and acid-etched (SLA), SLA modified with Dopa (SLA-Dopa), SLA modified with ZA (SLA-ZA), and SLA modified with Dopa and ZA (SLA-Dopa + ZA). Measurement of removal torque, micro-computed tomography and histology revealed a greater extent of bone formation around the three surface-modified implants than SLA-controls. No synergistic effect was observed for combined Dopa + ZA coating. Microarray analysis showed the Dopa coating inhibited expression of genes associated with osteoclast differentiation, similarly to the mechanism of action of ZA. Simple Dopa modification resulted in a similar improvement in osseointegration compared to ZA. Thus, our data suggest simple Dopa coating is promising strategy to promote osseointegration of implants in patients with osteoporosis.

  2. D-phenylalanine: a putative enkephalinase inhibitor studied in a primate acute pain model.

    PubMed

    Halpern, L M; Dong, W K

    1986-02-01

    D-Phenylalanine, along with morphine, acetylsalicylic acid and zomepirac sodium were evaluated for their antinociceptive actions in monkeys (M. fascicularis) trained to autoregulate nociceptive stimulation using a discrete-trials, aversive-threshold paradigm. Morphine sulfate produced dose-related increases in aversive threshold which were reversible after administration of naloxone (12.5 or 25 micrograms/kg i.m.). D-Phenylalanine (500 mg/kg p.o.) produced a small increase in aversive threshold which was not statistically significant and not naloxone reversible. Acetylsalicylic acid (200 mg/kg p.o.) but not zomepirac sodium (200 mg/kg p.o.) in combination with D-phenylalanine (500 mg/kg) produced a small statistically significant increase in aversive threshold. Our results argue against the hypothesis that D-phenylalanine is responsible for increasing aversive thresholds via opiate receptor mechanisms involving increased activity of enkephalins at synaptic loci. Previous studies by others in rats and mice showed that D-phenylalanine and acetylsalicylic acid produced increases in nociceptive thresholds which were naloxone reversible. Our failure to find opiate receptor mediated analgesia in a primate model with demonstrated opiate receptor selectivity and sensitivity is discussed in terms of previous basic and clinical research indicating an analgesic role for D-phenylalanine. Possible species difference in drug action is discussed in terms of inhibition by D-phenylalanine of carboxy-peptidase-like enkephalin processing enzymes as well as inhibition of carboxypeptidase-like enkephalin degrading enzymes.

  3. 30 CFR 56.5006 - Restricted use of chemicals.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... recognized agency acceptable to the Secretary. (a) Carbon tetrachloride. (b) Phenol, (c) 4-Nitrobiphenyl, (d... Dichlorobenzidine, (h) Bis (chloromethyl) ether, (i) Beta-napthylamine, (j) Benzidine, (k) 4-Aminodiphenyl, (l) Ethyleneimine, (m) Beta-propiolactone, (n) 2-Acetylaminofluorene, (o) 4-Dimethylaminobenzene, and (p) N...

  4. 30 CFR 56.5006 - Restricted use of chemicals.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... recognized agency acceptable to the Secretary. (a) Carbon tetrachloride. (b) Phenol, (c) 4-Nitrobiphenyl, (d... Dichlorobenzidine, (h) Bis (chloromethyl) ether, (i) Beta-napthylamine, (j) Benzidine, (k) 4-Aminodiphenyl, (l) Ethyleneimine, (m) Beta-propiolactone, (n) 2-Acetylaminofluorene, (o) 4-Dimethylaminobenzene, and (p) N...

  5. Synthesis and insect antifeedant activities of some substituted styryl 3,4-dichlorophenyl ketones

    NASA Astrophysics Data System (ADS)

    Thirunarayanan, G.; Surya, S.; Srinivasan, S.; Vanangamudi, G.; Sathiyendiran, V.

    2010-01-01

    Sixteen substituted styryl 3,4-dichlorophenyl ketones [ (2E)-1-(3,4-dichlorophenyl)-3-phenyl-2-propen-1-ones] were synthesized using eco-friendly benign stereoselective crossed-aldol reaction. They are characterized by their analytical, infrared, NMR and mass spectral data. The insect antifeedant activities of these chalcones were evaluated using Caster semilooper and Achoea janata L.

  6. Glycoprotein changes in non-insulin dependent diabetic rats: effect of N-benzoyl-D-phenylalanine and metformin.

    PubMed

    Pari, Leelavinothan; Ashokkumar, Natarajan

    2006-01-01

    The effect of N-benzoyl-D-phenylalanine (NBDP) and metformin on neonatal streptozotocin (nSTZ) induced diabetes has been studied on plasma and tissue glycoproteins. In some pathological conditions, such as cancer, rheumatoid arthritis and diabetes, there is an abnormal glycosylation of acute phase serum proteins. As most serum proteins are produced in the liver, we have examined glycoprotein metabolism in diabetic condition. To induce non-insulin-dependent diabetes mellitus (NIDDM) a single dose of streptozotocin (100 mg/kg body weight) was injected into two day old rats. After 10-12 weeks, rats weighing above 150 g were selected for NIDDM model. In these rat, blood glucose and plasma glycoproteins were significantly increased whereas plasma insulin was significantly decreased. There was a significant decrease in the level of sialic acid and elevated levels of hexose, hexosamine and fucose in tissues. Oral administration of NBDP and metformin to diabetic rats decreased blood glucose and plasma glycoproteins. Plasma insulin and tissue sialic acid were increased whereas tissue concentrations of hexose, hexosamine and fucose were near normal. Our study suggests that NBDP and metformin possess a significant beneficial effect on glycoproteins in addition to their antidiabetic effect.

  7. Bioproduction of L-Aspartic Acid and Cinnamic Acid by L-Aspartate Ammonia Lyase from Pseudomonas aeruginosa PAO1.

    PubMed

    Patel, Arti T; Akhani, Rekha C; Patel, Manisha J; Dedania, Samir R; Patel, Darshan H

    2017-06-01

    Aspartase (L-aspartate ammonia lyase, EC 4.3.1.1) catalyses the reversible amination and deamination of L-aspartic acid to fumaric acid which can be used to produce important biochemical. In this study, we have explored the characteristics of aspartase from Pseudomonas aeruginosa PAO1 (PA-AspA). To overproduce PA-AspA, the 1425-bp gene was introduced in Escherichia coli BL21 and purified. A 51.0-kDa protein was observed as a homogenous purified protein on SDS-PAGE. The enzyme was optimally active at pH 8.0 and 35 °C. PA-AspA has retained 56% activity after 7 days of incubation at 35 °C, which displays the hyperthermostablility characteristics of the enzyme. PA-AspA is activated in the presence of metal ions and Mg2+ is found to be most effective. Among the substrates tested for specificity of PA-AspA, L-phenylalanine (38.35 ± 2.68) showed the highest specific activity followed by L-aspartic acid (31.21 ± 3.31) and fumarate (5.42 ± 2.94). K m values for L-phenylalanine, L-aspartic acid and fumarate were 1.71 mM, 0.346 μM and 2 M, respectively. The catalytic efficiency (k cat /K m ) for L-aspartic acid (14.18 s -1  mM -1 ) was higher than that for L-phenylalanine (4.65 s -1  mM -1 ). For bioconversion, from an initial concentration of 1000 mM of fumarate and 30 mM of L-phenylalanine, PA-AspA was found to convert 395.31 μM L-aspartic acid and 3.47 mM cinnamic acid, respectively.

  8. Heterologous pathway for the production of L-phenylglycine from glucose by E. coli.

    PubMed

    Liu, Shuang Ping; Liu, Rui Xia; El-Rotail, Ashraf A M M; Ding, Zhong Yang; Gu, Zheng Hua; Zhang, Liang; Shi, Gui Yang

    2014-09-30

    The aproteinogenic amino acid L-phenylglycine (L-Phg) is an important side chain building block for the preparation of several antibiotics and taxol. To biosynthesis L-Phg from glucose, an engineered Escherichia coli containing L-Phg synthetic genes was firstly developed by an L-phenylalanine producing chassis supplying phenylpyruvate. The enzymes HmaS (L-4-hydroxymandelate synthase), Hmo (L-4-hydroxymandelate oxidase) and HpgT (L-4-hydroxyphenylglycine transaminase) from Amycolatopsis orientalis as well as Streptomyces coelicolor were heterologously expressed in E. coli and purified to evaluate their abilities on L-Phg formation. HpgT conversing phenylglyoxylate to L-Phg uses an unusual amino donor L-phenylalanine, which releases another phenylpyruvate as the substrate of HmaS. Thus, a recycle reaction was developed to maximize the utilization of precursor phenylpyruvate. To amplify the accumulation of L-Phg, the effects of attenuating L-phenylalanine transamination was investigated. After deletion of tyrB and aspC, L-Phg yield increased by 12.6-fold. The limiting step in the L-Phg biosynthesis was also studied; the L-Phg yield was further improved by 14.9-fold after enhancing hmaS expression. Finally, by optimizing expression of hmaS, hmo and hpgT and attenuation of L-phenylalanine transamination, the L-Phg yield was increased by 224-fold comparing with the original strain. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Ketone Bodies and Exercise Performance: The Next Magic Bullet or Merely Hype?

    PubMed

    Pinckaers, Philippe J M; Churchward-Venne, Tyler A; Bailey, David; van Loon, Luc J C

    2017-03-01

    Elite athletes and coaches are in a constant search for training methods and nutritional strategies to support training and recovery efforts that may ultimately maximize athletes' performance. Recently, there has been a re-emerging interest in the role of ketone bodies in exercise metabolism, with considerable media speculation about ketone body supplements being routinely used by professional cyclists. Ketone bodies can serve as an important energy substrate under certain conditions, such as starvation, and can modulate carbohydrate and lipid metabolism. Dietary strategies to increase endogenous ketone body availability (i.e., a ketogenic diet) require a diet high in lipids and low in carbohydrates for ~4 days to induce nutritional ketosis. However, a high fat, low carbohydrate ketogenic diet may impair exercise performance via reducing the capacity to utilize carbohydrate, which forms a key fuel source for skeletal muscle during intense endurance-type exercise. Recently, ketone body supplements (ketone salts and esters) have emerged and may be used to rapidly increase ketone body availability, without the need to first adapt to a ketogenic diet. However, the extent to which ketone bodies regulate skeletal muscle bioenergetics and substrate metabolism during prolonged endurance-type exercise of varying intensity and duration remains unknown. Therefore, at present there are no data available to suggest that ingestion of ketone bodies during exercise improves athletes' performance under conditions where evidence-based nutritional strategies are applied appropriately.

  10. Transition-metal-free synthesis of imidazo[2,1-b]thiazoles and thiazolo[3,2-a]benzimidazoles via an S-propargylation/5-exo-dig cyclization/isomerization sequence using propargyl tosylates as substrates.

    PubMed

    Omar, Mohamed A; Frey, Wolfgang; Conrad, Jürgen; Beifuss, Uwe

    2014-11-07

    A transition-metal-free route for the synthesis of several N-fused heterocycles, including thiazolo[3,2-a]benzimidazoles and imidazo[2,1-b]thiazoles, is reported. The reaction between propargyl tosylates and 2-mercaptobenzimidazoles under basic conditions results in 3-substituted thiazolo[3,2-a]benzimidazoles, in yields up to 92% in a single synthesis step. With 2-mercaptoimidazoles as the substrate, the corresponding imidazo[2,1-b]thiazoles were exclusively obtained. The transformation is considered to proceed as an intermolecular S-propargylation that is followed by 5-exo-dig ring closure and double-bond isomerization.

  11. The extracellular calcium-sensing receptor is required for cholecystokinin secretion in response to l-phenylalanine in acutely isolated intestinal I cells

    PubMed Central

    Liou, Alice P.; Sei, Yoshitatsu; Zhao, Xilin; Feng, Jianying; Lu, Xinping; Thomas, Craig; Pechhold, Susanne; Raybould, Helen E.

    2011-01-01

    The extracellular calcium-sensing receptor (CaSR) has recently been recognized as an l-amino acid sensor and has been implicated in mediating cholecystokinin (CCK) secretion in response to aromatic amino acids. We investigated whether direct detection of l-phenylalanine (l-Phe) by CaSR results in CCK secretion in the native I cell. Fluorescence-activated cell sorting of duodenal I cells from CCK-enhanced green fluorescent protein (eGFP) transgenic mice demonstrated CaSR gene expression. Immunostaining of fixed and fresh duodenal tissue sections confirmed CaSR protein expression. Intracellular calcium fluxes were CaSR dependent, stereoselective for l-Phe over d-Phe, and responsive to type II calcimimetic cinacalcet in CCK-eGFP cells. Additionally, CCK secretion by an isolated I cell population was increased by 30 and 62% in response to l-Phe in the presence of physiological (1.26 mM) and superphysiological (2.5 mM) extracellular calcium concentrations, respectively. While the deletion of CaSR from CCK-eGFP cells did not affect basal CCK secretion, the effect of l-Phe or cinacalcet on intracellular calcium flux was lost. In fact, both secretagogues, as well as superphysiological Ca2+, evoked an unexpected 20–30% decrease in CCK secretion compared with basal secretion in CaSR−/− CCK-eGFP cells. CCK secretion in response to KCl or tryptone was unaffected by the absence of CaSR. The present data suggest that CaSR is required for hormone secretion in the specific response to l-Phe by the native I cell, and that a receptor-mediated mechanism may inhibit hormone secretion in the absence of a fully functional CaSR. PMID:21252045

  12. Role of Intramolecular Aromatic π-π Interactions in the Self-Assembly of Di-l-Phenylalanine Dipeptide Driven by Intermolecular Interactions: Effect of Alanine Substitution.

    PubMed

    Reddy, Samala Murali Mohan; Shanmugam, Ganesh

    2016-09-19

    Although the role of intermolecular aromatic π-π interactions in the self-assembly of di-l-phenylalanine (l-Phe-l-Phe, FF), a peptide that is known for hierarchical structure, is well established, the influence of intramolecular π-π interactions on the morphology of the self-assembled structure of FF has not been studied. Herein, the role of intramolecular aromatic π-π interactions is investigated for FF and analogous alanine (Ala)-containing dipeptides, namely, l-Phe-l-Ala (FA) and l-Ala-l-Phe (AF). The results reveal that these dipeptides not only form self-assemblies, but also exhibit remarkable differences in structural morphology. The morphological differences between FF and the analogues indicate the importance of intramolecular π-π interactions, and the structural difference between FA and AF demonstrates the crucial role of the nature of intramolecular side-chain interactions (aromatic-aliphatic or aliphatic-aromatic), in addition to intermolecular interactions, in deciding the final morphology of the self-assembled structure. The current results emphasise that intramolecular aromatic π-π interaction may not be essential to induce self-assembly in smaller peptides, and π (aromatic)-alkyl or alkyl-π (aromatic) interactions may be sufficient. This work also illustrates the versatility of aromatic and a combination of aromatic and aliphatic residues in dipeptides in the formation of structurally diverse self-assembled structures. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Analysis of optical purity and impurity of synthetic D-phenylalanine products using sulfated beta-cyclodextrin as chiral selector by reversed-polarity capillary electrophoresis.

    PubMed

    Zhao, Yan; Yang, Xing-Bin; Jiang, Ru; Sun, Xiao-Li; Li, Xiao-Ye; Liu, Wen-Min; Zhang, Sheng-Yong

    2006-02-01

    A new capillary electrophoresis (CE) method has been achieved for simultaneous separation and quantification of phenylalanine, N-acetylphenylalanine enantiomers, and prochiral N-acetylaminocinnamic acid, possibly co-existent in reaction systems or synthesized products of D-phenylalanine. The separation was carried out in an uncoated capillary under reversed-electrophoretic mode. Among the diverse charged cyclodextrins (CDs) examined, highly sulfated (HS)-beta-CD as the chiral selector exhibited the best enantioselectivity. The complete separation of the analytes was obtained under the optimum conditions of pH 2.5, 35 mM Tris buffer containing 4% HS-beta-CD, applied voltage -15 kV, and capillary temperature 25 degrees C. Furthermore, the proposed method was applied to the determination of optical purity and trace impurities in three batches of the asymmetric synthetic samples of D-phenylalanine, and satisfactory results were obtained. The determination recoveries of the samples were in the range of 97.8-103.8%, and precisions fell within 2.3-5.0% (RSD). The results demonstrate that this CE method is a useful, simple technique and is applicable to purity assays of D-phenylalanine. (c) 2005 Wiley-Liss, Inc.

  14. 21 CFR 582.5590 - Phenylalanine.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Phenylalanine. 582.5590 Section 582.5590 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements...

  15. 21 CFR 582.5590 - Phenylalanine.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Phenylalanine. 582.5590 Section 582.5590 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements...

  16. 21 CFR 582.5590 - Phenylalanine.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Phenylalanine. 582.5590 Section 582.5590 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements...

  17. 21 CFR 582.5590 - Phenylalanine.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Phenylalanine. 582.5590 Section 582.5590 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements...

  18. 21 CFR 582.5590 - Phenylalanine.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Phenylalanine. 582.5590 Section 582.5590 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements...

  19. Influence of aliphatic spacer group on adsorption mechanisms of phosphonate derivatives of L-phenylalanine: Surface-enhanced Raman, Raman, and infrared studies

    NASA Astrophysics Data System (ADS)

    Podstawka, E.; Kudelski, A.; Kafarski, P.; Proniewicz, L. M.

    2007-10-01

    The nature of phosphonopeptides containing N-terminal L-phenylalanine ( L-Phe), namely L-Phe- DL-NH-CH(CH(CH 3) 2)-PO 3H 2 ( A), L-Phe- L-NH-CH(CH 3)-PO 3H 2 ( B), and L-Phe- DL-NH-CH(CH 2CH 2COOH)-PO 3H 2 ( C) ( Fig. 1 presents molecular structure of these molecules), adsorbed on electrochemically roughened and colloidal silver surfaces has been explored by surface-enhanced Raman spectroscopy (SERS). To reveal adsorption mechanism of these species on the basis of their SERS spectra at first Fourier-transform Raman (FT-RS) and absorption infrared (FT-IR) spectra of non-adsorbed molecules were measured. Examination of enhancement, frequency shifts, and changes in relative intensities of SERS bands due to adsorption and surface roughens variation reveals that the tilted compounds adsorb on the electrochemically roughened silver substrate in similar way, while they behave differently on the colloidal silver surface. A stronger enhancement of in-plane ring vibrations of the L-Phe ring, i.e., ν3 and ν18b (B 2), over these of the A 2 symmetry in all SERS spectra on the electrochemically roughened silver substrate suggests that the ring interacts with this surface adopting slightly deflect orientation from the perpendicular one. Also, enhancement of P dbnd O and -CH 2-/-CH 3 fragments vibrations points out that they are involved in adsorption process on this substrate. This conclusion was drawn on the basis of the enhancement of 1274-1279 and 1138-1152 ( ν(P dbnd O)), 1393-1400 ( δ(CH) + ρb(CNH 2) + ν(C-C dbnd O ) + δ(CH 3)), ˜1455 ( δ(CCH 3/CCH 2) + ρb(CH 3/CH 2), and 1505-1512 cm -1 ( δ(CH 2) + Phe( ν19a)) bands. Although a relative intensity ratio of these bands in the presented SERS spectra is different. On the other hand, on the colloidal silver nanoparticles, the aromatic ring of all molecules is lying flat or takes almost parallel orientation to this surface. Besides, A interacts also via P-terminal group (568, 765, 827, 1040, and 1150 cm -1), whereas B

  20. Efficient Hydrogenation of Ketones and Aldehydes Catalyzed by Well-Defined Iron(II) PNP Pincer Complexes: Evidence for an Insertion Mechanism

    PubMed Central

    2014-01-01

    We have prepared and structurally characterized a new class of Fe(II) PNP pincer hydride complexes [Fe(PNP-iPr)(H)(CO)(L)]n (L = Br–, CH3CN, pyridine, PMe3, SCN–, CO, BH4–; n = 0, +1) based on the 2,6-diaminopyridine scaffold where the PiPr2 moieties of the PNP ligand are connected to the pyridine ring via NH and/or NMe spacers. Complexes [Fe(PNP-iPr)(H)(CO)(L)]n with labile ligands (L = Br–, CH3CN, BH4–) and NH spacers are efficient catalysts for the hydrogenation of both ketones and aldehydes to alcohols under mild conditions, while those containing inert ligands (L = pyridine, PMe3, SCN–, CO) are catalytically inactive. Interestingly, complex [Fe(PNPMe-iPr)(H)(CO)(Br)], featuring NMe spacers, is an efficient catalyst for the chemoselective hydrogenation of aldehydes. The first type of complexes involves deprotonation of the PNP ligand as well as heterolytic dihydrogen cleavage via metal-alkoxide cooperation, but no reversible aromatization/deprotonation of the PNP ligand. In the case of the N-methylated complex the mechanism remains unclear, but obviously does not allow bifunctional activation of dihydrogen. The experimental results complemented by DFT calculations strongly support an insertion of the C=O bond of the carbonyl compound into the Fe–H bond. PMID:27642211