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1

Increasing Valine, Isoleucine, and Total BranchedChain Amino Acids for Lactating Sows1,2  

Microsoft Academic Search

One hundred eighty-five (n = 24 to 27\\/group; average parity 1.3) sows (PIC, Line C-15) were used to evaluate effects of the interrelationship between isoleucine and valine on sow and litter performance. Diets were formulated to .90% total lysine with all amino acids other than isoleucine and valine at least 110% of their suggested requirement estimate relative to lysine using

B. T. Richert; R. D. Goodband; M. D. Tokach; J. L. Nelssen

2

Biosynthesis of Food Constituents: Amino Acids: 2. The Alanine-Valine-Leucine, Serine-Cysteine-Glycine, and Aromatic and Heterocyclic Amino Acids Groups - a Review  

Microsoft Academic Search

VELÍŠEK J., CEJPEK K. (2006): Biosynthesis of food constituents: Amino acids: 2. The alanine-valine- leucine, serine-cysteine-glycine, and aromatic and heterocyclic amino acids groups - a review. Czech J. Food Sci., 24: 45-58. This review article gives a survey of principal pathways that lead to the biosynthesis of the proteinogenic amino acids of the alanine-valine-leucine group starting with pyruvic acid from

KAREL CEJPEK

3

Branched-chain amino acid interactions with reference to amino acid requirements in adult men: Valine metabolism at different leucine intakes  

SciTech Connect

The authors explored whether the oxidation of valine and by implication the physiological requirement for this amino acid are affected by changes in leucine intake over a physiological range. Six young adult men received, in random order, four L-amino acid-based diets for 5 d supplying either 20 or 10 mg valine.kg body wt-1.d-1, each in combination with 80 or 40 mg leucine.kg-1.d-1. On day 6 subjects were studied with an 8-h continuous intravenous infusion of (1-13C)valine (and (2H3)leucine) to determine valine oxidation in the fasted state (first 3 h) and fed state (last 5 h). Valine oxidation in the fasted state was similar among all diets but was lower (P less than 0.05) in the fed state for the 10 vs 20 mg valine.kg-1.d-1 intake. Leucine intake did not affect valine oxidation. Mean daily valine balance approximated +1.3 mg.kg-1.d-1 for the 20-mg intake and -1.6 mg.kg-1.d-1 for the 10-mg intake. These findings support our previously suggested mean valine requirement estimate of approximately 20 mg.kg-1.d-1.

Pelletier, V.; Marks, L.; Wagner, D.A.; Hoerr, R.A.; Young, V.R. (Laboratory of Human Nutrition, Massachusetts Institute of Technology, Cambridge (USA))

1991-08-01

4

Are alanine, cysteine, glycine and valine amino acids the cause of non-immune hydrops fetalis?  

PubMed

Our objective was to measure amniotic fluid amino acid concentrations in pregnant women diagnosed as having fetuses with non immune hydrops fetalis in the second trimester of pregnancy. Twenty-three pregnant women who had fetuses with non immune hydrops fetalis detected by ultrasonography (non immune hydrops fetalis group) in the second trimester and 19 women who had healthy fetuses (control group) were enrolled in the study. Amniotic fluid was obtained by amniocentesis. The chromosomal analysis of the study and control groups was normal. Levels of free amino acids were measured in amniotic fluid samples using EZ: fast kits (EZ: fast GC/FID free (physiological) amino acid kit) by gas chromatography (Focus GC Al 3000 Thermo Finnigan analyzer). The mean levels of alanine, cysteine, glycine and valine amino acids were found to be significantly higher in fetuses with non immune hydrops fetalis than in the control group (p<0.05). The detection of significantly higher amino acid concentrations in the amniotic fluid of fetuses with a non immune hydrops fetalis in healthy fetuses suggests loss of amino acids from the fetus through capillary permeability or/and the lymphatic system through the amniotic fluid may contribute to the etiology of non-immune hydrops fetalis. PMID:23157039

Kale, A; Kale, E

2012-01-01

5

Sequence, transcriptional, and functional analyses of the valine (branched-chain amino acid) dehydrogenase gene of Streptomyces coelicolor.  

PubMed Central

The gene encoding the valine (branched-chain amino acid) dehydrogenase (Vdh) from Streptomyces coelicolor has been characterized as follows. The vdh gene was identified by hybridization to a specific oligodeoxynucleotide that was synthesized on the basis of the N-terminal amino acid sequence of purified Vdh. Nucleotide sequence analysis predicts that the vdh gene contains a 364-amino-acid open reading frame that should produce a 38,305-M(r) protein. The deduced amino acid sequence of the Vdh protein is significantly similar to those of several other amino acid dehydrogenases, especially the leucine and phenylalanine dehydrogenases from Bacillus spp. The vdh gene is apparently transcribed from a single major transcriptional start point, separated by only 8 bp from the 5' end of a divergent transcript and located 63 bp upstream from the vdh translational start point. Mutants with a disrupted vdh gene have no detectable Vdh activity and have lost the ability to grow on valine, leucine, or isoleucine as the sole nitrogen source. This vdh mutation does not significantly affect growth or actinorhodin production in a minimal medium, yet the addition of 0.2% L-valine to the medium provokes approximately 32 and 80% increases in actinorhodin production in vdh+ and vdh strains, respectively. Images

Tang, L; Hutchinson, C R

1993-01-01

6

Synthesis and characterization of novel, optically active polyamides derived from S -valine natural amino acid and bulky anthracenic side chain  

Microsoft Academic Search

This is the first description of the application of molten tetrabutylammonium bromide (TBAB) in the presence of triphenyl\\u000a phosphite (TPP) for the synthesis of novel polyamides (PAs). Monomer diacid, 5-[(9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximido)-3-methylbutanoylamino]isophthalic\\u000a acid (4), having anthracenic and amino acid S-valine pendant group, was synthesized in four steps. Several novel, optically active\\u000a PAs were prepared by the condensation of synthesized diacid monomer 4

Fatemeh Mirkarimi

2010-01-01

7

Identification of a highly conserved valine-glycine-phenylalanine amino acid triplet required for HIV-1 Nef function  

PubMed Central

Background The Nef protein of HIV facilitates virus replication and disease progression in infected patients. This role as pathogenesis factor depends on several genetically separable Nef functions that are mediated by interactions of highly conserved protein-protein interaction motifs with different host cell proteins. By studying the functionality of a series of nef alleles from clinical isolates, we identified a dysfunctional HIV group O Nef in which a highly conserved valine-glycine-phenylalanine (VGF) region, which links a preceding acidic cluster with the following proline-rich motif into an amphipathic surface was deleted. In this study, we aimed to study the functional importance of this VGF region. Results The dysfunctional HIV group O8 nef allele was restored to the consensus sequence, and mutants of canonical (NL4.3, NA-7, SF2) and non-canonical (B2 and C1422) HIV-1 group M nef alleles were generated in which the amino acids of the VGF region were changed into alanines (VGF?AAA) and tested for their capacity to interfere with surface receptor trafficking, signal transduction and enhancement of viral replication and infectivity. We found the VGF motif, and each individual amino acid of this motif, to be critical for downregulation of MHC-I and CXCR4. Moreover, Nef’s association with the cellular p21-activated kinase 2 (PAK2), the resulting deregulation of cofilin and inhibition of host cell actin remodeling, and targeting of Lck kinase to the trans-golgi-network (TGN) were affected as well. Of particular interest, VGF integrity was essential for Nef-mediated enhancement of HIV virion infectivity and HIV replication in peripheral blood lymphocytes. For targeting of Lck kinase to the TGN and viral infectivity, especially the phenylalanine of the triplet was essential. At the molecular level, the VGF motif was required for the physical interaction of the adjacent proline-rich motif with Hck. Conclusion Based on these findings, we propose that this highly conserved three amino acid VGF motif together with the acidic cluster and the proline-rich motif form a previously unrecognized amphipathic surface on Nef. This surface appears to be essential for the majority of Nef functions and thus represents a prime target for the pharmacological inhibition of Nef.

2012-01-01

8

Thermal, Dielectric Studies on Pure and Amino Acid L-Glutamic Acid, L-Histidine L-Valine Doped Potassium Dihydrogen Phosphate Single Crystals  

NASA Astrophysics Data System (ADS)

Amino acids (L-Glutamic acid, L-Histidine, L-Valine) doped potassium dihydrogen phosphate crystals were grown by the solution growth technique. Slow cooling as well as slow evaporation methods were employed to grow these crystals. The concentration of dopants in the mother solution was varied from 0.1 mole % to 10 mole %. The solubility data for all dopant concentrations were determined. The variation in pH and the corresponding habit modification of the grown crystals were characterized with UV - VIS, FT-IR and SHG trace elements, and dielectric studies reveal slight distortion of lattice parameter for the heavily doped KDP crystals. TGA-DTA studies reveal good thermal stability. The dopants increase the hardness value of the material, which also depends on the concentration of the dopants. Amino acids doping improved the NLO properties. The detailed results on the spectral parameters, habit modifications and constant values will be presented.

Kumaresan, P.; Babu, S. Moorthy; Anbarasan, P. M.

9

Measurement of activity coefficients of amino acids in aqueous electrolyte solutions: experimental data for the systems (H 2O + NaBr + glycine) and (H 2O + NaBr + l-valine) at T=298.15 K  

Microsoft Academic Search

Electrochemical cells with two ion-selective electrodes, a cation ion-selective electrode against an anion ion-selective electrode, were used to measure the activity coefficient of amino acids in aqueous electrolyte solutions. Activity coefficient data were measured for (H2O+NaBr+glycine) and (H2O+NaBr+l-valine) at T=298.15 K. The maximum concentrations of sodium bromide, glycine, and l-valine were (1.0, 2.4, and 0.4) mol·kg?1, respectively. The results show

A. Khavaninzadeh; H. Modarress; V. Taghikhani; M. K. Khoshkbarchi

2003-01-01

10

Synthesis and characterization of novel, optically active polyamides derived from S-valine natural amino acid and bulky anthracenic side chain.  

PubMed

This is the first description of the application of molten tetrabutylammonium bromide (TBAB) in the presence of triphenyl phosphite (TPP) for the synthesis of novel polyamides (PAs). Monomer diacid, 5-[(9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximido)-3-methylbutanoylamino]isophthalic acid (4), having anthracenic and amino acid S-valine pendant group, was synthesized in four steps. Several novel, optically active PAs were prepared by the condensation of synthesized diacid monomer 4 with various aromatic diamines using two different techniques: a mixture of N-methyl-2-pyrrolidone (NMP)/TPP/pyridine/calcium chloride (method I) and combination of TPP with TBAB (method II). The main goal of the present paper was to prepare novel PAs in a green media by removal of toxic reagents. Therefore, TBAB/TPP was used as a novel, easy, safe and eco-friendly method for the preparation of aromatic PAs. This method is compared with the polymerization reaction under conventional solvent and in the case of TBAB as a new method, higher yields, inherent viscosities and thermally stable of PAs are gained. The resulting polymers showed good solubility in polar aprotic solvents such as dimethyl sulfoxide, NMP, N,N-dimethylacetamide and N,N-dimethylformamide. These polymers are characterized with respect to chemical structure and purity by means of specific rotation experiments, FT-IR, 1H NMR spectroscopy techniques and elemental analysis. The obtained PAs exhibit good thermal stability up to 335°C for 10% weight loss in nitrogen atmosphere and glass transition temperatures fell in the rang of 177-185°C. PMID:20352462

Mallakpour, Shadpour; Mirkarimi, Fatemeh

2010-03-30

11

INFLUENCE OF INDIVIDUAL AMINO ACIDS ON UPTAKE AND INCORPORATION OF VALINE, GLUTAMIC ACID AND ARGININE BY UNFERTILIZED AND FERTILIZED SEA URCHIN EGGS  

Microsoft Academic Search

In the course of investigations (cf. Tyler, 1965a) into the mechanism of the initiation of protein synthesis by sea urchin eggs, some variable results were obtained in tests with dactinoniycin (actinomycin D) . This inhibitor of DNA primed RNA synthesis stimulated incorporation of labeled valine into protein in four experiments with suspensions of eggs that contained many oocytes but failed

ALBERT TYLER; JORAM PIATIGORSKY

12

Precision neutron diffraction structure determination of protein and nucleic acid components. XV. Crystal and molecular structure of the amino acid L-valine hydrochloride  

Microsoft Academic Search

A neutron diffraction study of L-valine · HCl has been carried out: space group P21, a = 10.382(2), b = 7.066(1), c = 5.4407(9) Å, ? = 91.40(2)°, Z = 2. The structure has been refined by full-matrix least-squares techniques with anisotropic temperature factors for all atoms and with a Type II anisotropic extinction correction, leading to a conventional R

Thomas F. Koetzle; Ljubo Golic; Mogens S. Lehmann; Jacques J. Verbist; Walter C. Hamilton

1974-01-01

13

Precision neutron diffraction structure determination of protein and nucleic acid components. XV. Crystal and molecular structure of the amino acid L-valine hydrochloride  

Microsoft Academic Search

A neutron diffraction study of L-valine . HCl has been carried out: space group P21, a = 10.382(2), b = 7.066(1), c = 5.4407(9) Å, beta = 91.40(2)°, Z = 2. The structure has been refined by full-matrix least-squares techniques with anisotropic temperature factors for all atoms and with a Type II anisotropic extinction correction, leading to a conventional R

Thomas F. Koetzle; Ljubo Golic; Mogens S. Lehmann; Jacques J. Verbist; Walter C. Hamilton

1974-01-01

14

Effects of feeding a ruminally protected lysine product, with or without isoleucine, valine and histidine, to lactating dairy cows on their productive performance and plasma amino acid profiles  

Microsoft Academic Search

The literature on post-ruminal lysine supplementation to diets of lactating dairy cows shows generally small negative responses to supplemental intestinally absorbable lysine, and our recent metabolic modeling of California dairy rations predicted other amino acid (AA) that could become co-limiting if supplies of intestinally absorbable lysine were met. The objectives of this study were to estimate the rumen escape potential

P. H. Robinson; N. Swanepoel; E. Evans

2010-01-01

15

Amino acid composition in Isoparorchis hypselobagri  

Microsoft Academic Search

Summary The free amino acids of Isoparorchis hypselobagri have been determined by the chromatographic method (two-dimensional ascending). These are: leucine, valine, proline, alanine, glycine, glutamic acid and aspartic acid.

Meenakshi Srivastava; S. P. Gupta

1976-01-01

16

Effect of L-Valine on the growth and characterization of Sodium Acid Phthalate (SAP) single crystals  

NASA Astrophysics Data System (ADS)

Undoped and amino acid doped good quality single crystals of Sodium Acid Phthalate crystals (SAP) were grown by slow evaporation solution growth technique which are semiorganic in nature. The effect of amino acid (L-Valine) dopant on the growth and the properties of SAP single crystal was investigated. The single crystal X-ray diffraction studies and FT-IR studies were carried out to identify the crystal structure and the presence of functional groups in undoped and L-Valine doped SAP crystals. The transparent nature of the grown crystal was observed using UV-Visible spectrum. The thermal decomposition of the doped SAP crystals was investigated by thermo gravimetric analysis (TGA) and differential thermal analysis (DTA). The enhancement in the NLO property of the undoped and L-Valine doped SAP crystals using KDP crystal as a reference was studied using SHG measurements. Vickers micro hardness measurements are used for the study of mechanical strength of the grown crystals.

Nirmala, L. Ruby; Prakash, J. Thomas Joseph

2013-06-01

17

Amino Acid Concentrations in Rumen Fluid  

PubMed Central

Methods using dialysis or ultrafiltration are described for the collection of extracellular fluid in rumen contents for analysis of amino acids. Marked differences in the concentration of aspartic acid, glutamic acid, and alanine were found in samples of either diffusate or ultrafiltrate and in clarified acidified rumen liquor. Concentrations are given for aspartic acid, glutamic acid, alanine, glycine, ?-aminobutyric acid, valine, ?-aminovaleric acid, and leucine.

Wright, D. E.; Hungate, R. E.

1967-01-01

18

AMINO ACID CROSS RESISTANCE IN AGROBACTERIUM TUMEFACIENS  

PubMed Central

Beardsley, Robert E. (Manhattan College, New York, N. Y.). Amino acid cross resistance in Agrobacterium tumefaciens. J. Bacteriol. 84:1237–1240. 1962.—Resistant clones selected on medium supplemented with glycine were also resistant to d-methionine, d-valine, dl-norleucine, and dl-serine. Cross resistance was similarly exhibited by clones selected on d-methionine, d-valine, or dl-norleucine. Two types of resistant organisms were observed. One produced colonies containing normal rods on selection medium. The other produced translucent colonies containing L forms. Both grew as typical rods in unsupplemented medium. Some resistant clones did not produce a temperate phage carried by the parental strain, but these retained immunity to homologous phage. The toxicity of d-methionine and d-valine for nonresistant bacteria is not reversed by the l isomers. The lethal effects of toxic amino acids are additive.

Beardsley, Robert E.

1962-01-01

19

Effect of L-Valine on the growth and characterization of Sodium Acid Phthalate (SAP) single crystals.  

PubMed

Undoped and amino acid doped good quality single crystals of Sodium Acid Phthalate crystals (SAP) were grown by slow evaporation solution growth technique which are semiorganic in nature. The effect of amino acid (L-Valine) dopant on the growth and the properties of SAP single crystal was investigated. The single crystal X-ray diffraction studies and FT-IR studies were carried out to identify the crystal structure and the presence of functional groups in undoped and L-Valine doped SAP crystals. The transparent nature of the grown crystal was observed using UV-Visible spectrum. The thermal decomposition of the doped SAP crystals was investigated by thermo gravimetric analysis (TGA) and differential thermal analysis (DTA). The enhancement in the NLO property of the undoped and L-Valine doped SAP crystals using KDP crystal as a reference was studied using SHG measurements. Vickers micro hardness measurements are used for the study of mechanical strength of the grown crystals. PMID:23583879

Nirmala, L Ruby; Thomas Joseph Prakash, J

2013-03-25

20

Characterisation of a glycine to valine substitution at amino acid position 910 of the triple helical region of type III collagen in a patient with Ehlers-Danlos syndrome type IV.  

PubMed Central

We have studied a patient with Ehlers-Danlos syndrome type IV. Protein mapping studies of her type III collagen had indicated that cyanogen bromide fragment 9 contained the site of the mutation. Here we describe the mapping of this region for a single base mutation using a chemical modification and cleavage technique. Sequence analysis of cDNA showed a G to T mutation resulting in the substitution of glycine 910 by valine. This was confirmed by allele specific oligonucleotide hybridisation to the proband's genomic DNA. Images

Richards, A J; Lloyd, J C; Ward, P N; De Paepe, A; Narcisi, P; Pope, F M

1991-01-01

21

Uptake of Branched-Chain Amino Acids by Streptococcus thermophilus  

PubMed Central

The transport of branched-chain amino acids in Streptococcus thermophilus was energy dependent. The metabolic inhibitors of glycolysis and ATPase enzymes were active, but the proton-conducting uncouplers were not. Transport was optimal at temperatures of between 30 and 45°C and at pH 7.0 for the three amino acids leucine, valine, and isoleucine; a second peak existed at pH 5.0 with valine and isoleucine. By competition and kinetics studies, the branched-chain amino acids were found to share at least a common transport system.

Akpemado, K. M.; Bracquart, P. A.

1983-01-01

22

The establishment of essential and metabolically derived amino acid profiles in developing chick embryo organs  

Microsoft Academic Search

The accumulation of certain essential and metabolically derived amino acids in the free amino acid pools of three excitable tissues has been studied in the chick embryo. Valine together with leucine are at the onset present in the yolk at higher concentrations than any of the other essential amino acids. By 15 days all the amino acids studied have accumulated

N. M. Gelder; F. Bélanger

1988-01-01

23

Providing a diet deficient in valine but with excess leucine results in a rapid decrease in feed intake and modifies the postprandial plasma amino acid and ?-keto acid concentrations in pigs.  

PubMed

Indispensable AA are involved in the control of feed intake. When a diet deficient in Val is offered to pigs, feed intake is typically reduced. This effect is aggravated when dietary Leu is supplied in excess of the requirement. If an unbalanced supply of branched-chain AA (BCAA) is harmful, an anorectic response may serve as a mechanism to prevent this situation. We verified this hypothesis by measuring the voluntary feed intake of a balanced diet offered during the 30-min period 1 h after ingestion of a test meal deficient or not in Val (Val- and Val+) with an excess of Leu. Twelve and four 6-wk-old crossbred female pigs were used in Exp. 1 and 2, respectively. Prior ingestion of the Val- test meal resulted in a 14% reduction in feed intake compared with that observed after ingestion of the Val+ test meal (P = 0.06) in Exp. 1, indicating that the signal to reduce feed intake occurred within 1 h. It is possible that the plasma concentration of the limiting AA serves as a signal for the dietary AA deficiency. We therefore determined the postprandial plasma concentrations of BCAA and their ?-keto acids after ingestion of Val- and Val+ in 4 pigs in Exp. 2. After ingestion of the Val- diet, plasma concentrations of Val and its keto acid were reduced compared with values observed after ingestion of the Val+ diet. The peak concentration occurred earlier after ingestion of the Val- diet compared with that of the Val+ diet. Although the plasma concentration increased after the meal, it declined rapidly in pigs offered Val-, and the Val concentration 4 h after ingestion of the meal was even less than that observed in the fasted state. In conclusion, it appears that the pig is able to detect a deficient supply of Val within 1 h after ingestion. The plasma concentration of Val or its concentration relative to the other BCAA during the postprandial period may act as a signal indicating the AA deficiency. PMID:22585822

Gloaguen, M; Le Floc'h, N; Corrent, E; Primot, Y; van Milgen, J

2012-05-14

24

?-Amino acids  

Microsoft Academic Search

Summary 1.It has been established that by the decarboxylation of the glycidic acid, obtained by Darzens' method from cis-decahydro-2-naphthol of m.p. 105°, a mixture of stereoisomeric decahydro-2-naphthaldehydes is formed; these have not been investigated further.2.The synthesis has been affected, by Rodionov's method, of ß-(2-decalyl)-ß-alanine (ß-aminodecahydro-2-naphthalenepropionic acid), which also appeared to be a mixture of isomers, the separation of which was

V. M. Rodionov; L. V. Antik

1953-01-01

25

Branched-Chain Amino and Keto Acid Biochemistry and Cellular Biology in Central Nervous System Diseases.  

National Technical Information Service (NTIS)

Branched-chain amino acids (BCAAs: leucine, isoleucine, and valine) are essential components of many biochemical and biological processes. There are well-established pathways, such as fatty acid synthesis and oxidation, anabolic use to synthesize new prot...

J. Henriques

2009-01-01

26

Prebiotic Synthesis of Hydrophobic and Protein Amino Acids  

PubMed Central

The formation of amino acids by the action of electric discharges on a mixture of methane, nitrogen, and water with traces of ammonia was studied in detail. The presence of glycine, alanine, ?-amino-n-butyric acid, ?-aminoisobutyric acid, valine, norvaline, isovaline, leucine, isoleucine, alloisoleucine, norleucine, proline, aspartic acid, glutamic acid, serine, threonine, allothreonine, ?-hydroxy-?-aminobutyric acid, and ?,?-diaminobutyric acid was confirmed by ion-exchange chromatography and gas chromatography-mass spectrometry. All of the primary ?-amino acids found in the Murchison Meteorite have been synthesized by this electric discharge experiment.

Ring, David; Wolman, Yecheskel; Friedmann, Nadav; Miller, Stanley L.

1972-01-01

27

Mechanism of specific influence of L-Glutamic acid on the shape of L-Valine crystals  

NASA Astrophysics Data System (ADS)

The specific interaction between L-valine (L-Val) and L-glutamic acid (L-Glu) in the process of evaporative crystallization from an aqueous solution has been investigated. It was found that only 2.0% (wt/wt) of L-Glu against the total amount of L-Val was required to induce significant agglomeration of L-Val. Interestingly, the agglomeration was only induced under acidic conditions, suggesting that the electrostatic interaction was an effective factor for the agglomeration process. As well as the electrostatic interaction, the length of the amino acid side chain was identified as another important factor. In addition, we confirmed that the incorporation rate of L-Glu into L-Val crystals was different during the nucleation and crystal growth stages. Based on these results, a mechanism has been proposed for the interaction of L-Glu and L-Val during the agglomeration process.

Yoshiura, Hiromu; Nagano, Hiroshi; Hirasawa, Izumi

2013-01-01

28

Liquid membrane extraction and transport of amino acids using calix(6)arene  

Microsoft Academic Search

Calix(6)arene was utilized as an extractant as well as carrier for amino acids through liquid membrane. The receptor forms complex with amino acids by CH-? interactions, van der Waals interactions and hydrogen bonding. The host compound exhibited high fluxes for amino acids with high extraction efficiency i.e. valine and alanine due to its cyclic structure and cavity size. The sequence

Pankaj Raizada; Vaishali Vyas; Uma Sharma

2010-01-01

29

Amino acid availability affects amino acid flux and protein metabolism in the porcine mammary gland.  

PubMed

A kinetic model was used to examine transmembrane flux kinetics of lysine, methionine and valine across the porcine mammary gland (MG) under dietary amino acid (AA) limiting, adequate and excess conditions. Lactating sows (3 per treatment) were offered three diets: lysine-deficient [LD, 4.9 lysine and 9.9 valine (g/kg diet)], adequate (Control, 9.7 and 10.2) and valine-excess (VE, 9.8 and 13.4). On d 18 of lactation, 2-(15)N-lysine, 5-methyl-(2)H(3)-methionine and 1-(13)C-valine were infused into a jugular vein for 20.5 h. Milk and arterial and mammary venous blood samples were collected at 2- and 1-h intervals, respectively. Compared with Control, milk yield and litter growth rate decreased (P < 0.05) in sows fed the LD diet. Model estimates of mammary protein synthesis (PS), breakdown (PB) and net PS decreased (P < 0.05) in sows fed the LD diet. Net uptake of lysine decreased (P < 0.05) in sows fed the LD diet as a result of decreases in inward and outward transport of lysine. Inward transport of methionine tended to be reduced (P < 0.10) in sows fed the LD diet, resulting in a decrease in net methionine uptake. In sows fed the VE diet, PB was reduced (P < 0.05) and PS unchanged compared with Control. Outward transport of valine and net lysine uptake were reduced (P < 0.05), but net valine uptake was unchanged in sows fed the VE diet compared with Control. In conclusion, the kinetic model provided estimates of PS that were similar to empirical measurements of milk protein output and mammary protein accretion. Transport of lysine and methionine by the porcine MG is closely linked to regulation of mammary PS. Lysine availability has little effect on the transmembrane flux of valine. PMID:12042438

Guan, Xinfu; Bequette, Brian J; Calder, Graham; Ku, Pao K; Ames, Kent N; Trottier, Nathalie L

2002-06-01

30

Amino acid composition of the protein in pre-emergence nests of a paper wasp, Polistes chinensis (Hymenoptera, Vespidae)  

Microsoft Academic Search

Summary. Amino acid composition of protein in oral secretion, which is widely used for construction and maintenance of social wasp nests, was analyzed in pre-emergence nests of Polistes chinensis. More than 20 amino acids were detected from field and laboratory nests, among which glycine, serine, alanine, valine and proline were major amino acids in all samples analyzed. The amino acid

K. Kudô; H. Yamamoto; Sô Yamane

2000-01-01

31

The amino acid sequence of wood duck lysozyme.  

PubMed

The amino acid sequence of wood duck (Aix sponsa) lysozyme was analyzed. Carboxymethylated lysozyme was digested with trypsin and the resulting peptides were sequenced. The established amino acid sequence had the highest similarity to duck III lysozyme with four amino acid substitutions, and had eighteen amino acid substitutions from chicken lysozyme. The valine at position 75 was newly detected in chicken-type lysozymes. In the active site, Tyr34 and Glu57 were found at subsites F and D, respectively, when compared with chicken lysozyme. PMID:10052146

Araki, T; Torikata, T

1999-01-01

32

Kidney amino acid transport  

Microsoft Academic Search

Near complete reabsorption of filtered amino acids is a main specialized transport function of the kidney proximal tubule.\\u000a This evolutionary conserved task is carried out by a subset of luminal and basolateral transporters that together form the\\u000a transcellular amino acid transport machinery similar to that of small intestine. A number of other amino acid transporters\\u000a expressed in the basolateral membrane

François Verrey; Dustin Singer; Tamara Ramadan; Raphael N. Vuille-dit-Bille; Luca Mariotta; Simone M. R. Camargo

2009-01-01

33

Amino acids: Analytical aspects  

Microsoft Academic Search

This workshop was organized as a direct response to concerns and queries raised by laboratory personnel, both in Europe and in the United States, about the imminent withdrawal of Beckman Coulter from the amino acid analysis market. The topics covered included external quality control schemes, standard operating procedures for amino acid analysis and instrumentation, both from a user's perspective and

P. D. Mayne; G. Roche; D. Deverell

2001-01-01

34

Amino Acid Crossword Puzzle  

ERIC Educational Resources Information Center

|Learning the 20 standard amino acids is an essential component of an introductory course in biochemistry. Later in the course, the students study metabolism and learn about various catabolic and anabolic pathways involving amino acids. Learning new material or concepts often is easier if one can connect the new material to what one already knows;…

Sims, Paul A.

2011-01-01

35

A Single Acyl-CoA Dehydrogenase Is Required For Catabolism Of Isoleucine, Valine And Short-Chain Fatty Acids In Aspergillus nidulans  

PubMed Central

An acyl-CoA dehydrogenase has been identified as part of the mitochondrial ?-oxidation pathway in the ascomycete fungus Aspergillus nidulans. Disruption of the scdA gene prevented use of butyric acid (C4) and hexanoic acid (C6) as carbon sources and reduced cellular butyryl-CoA dehydrogenase activity by 7.5-fold. While the mutant strain exhibited wild-type levels of growth on erucic acid (C22:1) and oleic acid (C18:1), some reduction in growth was observed with myristic acid (C14). The ?scdA mutation was found to be epistatic to a mutation downstream in the ?-oxidation pathway (disruption of enoyl-CoA hydratase). The ?scdA mutant was also unable to use isoleucine or valine as a carbon source. Transcription of scdA was observed in the presence of either fatty acids or amino acids. When the mutant was grown in medium containing either isoleucine or valine, organic acid analysis of culture supernatants showed accumulation of 2-oxo acid intermediates of branched chain amino acid catabolism, suggesting feedback inhibition of the upstream branched-chain ?-keto acid dehydrogenase.

Maggio-Hall, Lori A.; Lyne, Paul; Wolff, Jon A.; Keller, Nancy P.

2010-01-01

36

Formation of Amino Acids from Reactor Irradiated Ammonium Acetate  

NASA Astrophysics Data System (ADS)

Ammonium acetate in various conditions was irradiated in a reactor to examine the contributions of both the reactor radiations and recoiled14C nucleis to form the biologically interesting molecules. Present investigations demonstrated that several amino acids, glycine, alanine, ?-alanine and GABA, and may-be aspartic acid, serine and valine by prolonged irradiation, were formed in the aqueous solutions of ammonium acetate.14C-radioactivities were also found distributed in these amino acids. However, no special relationship between14C-radioactivity and these amino acids formed was observed.

Akaboshi, M.; Kawai, K.; Maki, H.; Kawamoto, K.; Honda, Y.

1982-12-01

37

The prebiotic synthesis of amino acids - interstellar vs. atmospheric mechanisms  

NASA Astrophysics Data System (ADS)

Until very recently, prebiotic amino acids were believed to have been generated in the atmosphere of the early Earth, as successfully simulated by the Urey-Miller experiments. Two independent studies now identified ice photochemistry in the interstellar medium as a possible source of prebiotic amino acids. Ultraviolet irradiation of ice mixtures containing identified interstellar molecules (such as H2O, CO2, CO, CH3OH, and NH3) in the conditions of vacuum and low temperature found in the interstellar medium generated amino acid structures including glycine, alanine, serine, valine, proline, and aspartic acid. After warmup, hydrolysis and derivatization, our team was able to identify 16 amino acids as well as furans and pyrroles. Enantioselective analyses of the amino acids showed racemic mixtures. A prebiotic interstellar origin of amino acid structures is now discussed to be a plausible alternative to the Urey-Miller mechanism.

Meierhenrich, U. J.; Muñoz Caro, G. M.; Schutte, W. A.; Barbier, B.; Arcones Segovia, A.; Rosenbauer, H.; Thiemann, W. H.-P.; Brack, A.

2002-11-01

38

Studies in the polarography of metal-amino acid complexes  

Microsoft Academic Search

Summary  1. A detailed polarographic study of cadmium has been made employing glycine,?-alanine,?-alanine, valine, aspartic acid, glutamic acid and asparagine as complexing agents at various pH values. The effect of incorporating\\u000a sodium hydroxide, sodium carbonate and ammonium nitrate + ammonium hydroxide, on the polarographic behaviour of amino acid\\u000a complexes of cadmium has also been investigated.\\u000a \\u000a 2. The reduction process has been

G. Nageswara Rao; R. S. Subrahmanya

1964-01-01

39

Amino acid tolerance in cirrhotic patients following oral protein and amino acid loads.  

PubMed

Plasma amino acid and venous blood ammonia concentrations were measured in six patients with well-compensated cirrhosis and in six healthy volunteers, both in the fasting state and serially for 5 h following ingestion of 30 g mixed protein and 30 g amino acid mixture, administered on separate occasions. Mean fasting plasma concentrations of threonine, serine, proline, glycine, and of the three branched-chain amino acids, valine, isoleucine and leucine, were significantly reduced in the cirrhotic patients compared with the control subjects, while mean (+/- 1 s.d.) fasting venous blood ammonia concentrations were comparable 71.2 +/- 31.4 cf. 56.0 +/- 25.4 mumol/L. Following the oral protein and amino acid loads, increases were observed in plasma amino acid concentrations in the majority of subjects with a return to baseline values by the end of the study. Changes in the circulating concentrations of most amino acids were independent of their concentration in the oral protein and amino acid loads, and their relative distribution in the circulation varied over time. The increases in the concentrations of the three branched-chain amino acids did, however, reflect their concentrations in the two nitrogen loads and did remain constant, relative to one another, over time. There were wide intra- and inter-individual variations in plasma amino acid concentrations following protein and amino acid ingestion in both study groups, and in general no significant differences in responses were observed between them. Similarly, no significant inter-group differences were observed in the ammonia response to the two nitrogen loads. No fundamental differences exist in the ways in which patients with well-compensated cirrhosis handle oral protein or amino acid loads of the magnitude employed in the present study. PMID:2104085

Morgan, M Y; Hawley, K E; Stambuk, D

1990-04-01

40

Kidney amino acid transport.  

PubMed

Near complete reabsorption of filtered amino acids is a main specialized transport function of the kidney proximal tubule. This evolutionary conserved task is carried out by a subset of luminal and basolateral transporters that together form the transcellular amino acid transport machinery similar to that of small intestine. A number of other amino acid transporters expressed in the basolateral membrane of proximal kidney tubule cells subserve either specialized metabolic functions, such as the production of ammonium, or are part of the cellular housekeeping equipment. A new finding is that the luminal Na(+)-dependent neutral amino acid transporters of the SLC6 family require an associated protein for their surface expression as shown for the Hartnup transporter B(0)AT1 (SLC6A19) and suggested for the L: -proline transporter SIT1 (IMINO(B), SLC6A20) and for B(0)AT3 (XT2, SLC6A18). This accessory subunit called collectrin (TMEM27) is homologous to the transmembrane anchor region of the renin-angiotensin system enzyme ACE2 that we have shown to function in small intestine as associated subunit of the luminal SLC6 transporters B(0)AT1 and SIT1. Some mutations of B(0)AT1 differentially interact with these accessory subunits, providing an explanation for differential intestinal phenotypes among Hartnup patients. The basolateral efflux of numerous amino acids from kidney tubular cells is mediated by heteromeric amino acid transporters that function as obligatory exchangers. Thus, other transporters within the same membrane need to mediate the net efflux of exchange substrates, controlling thereby the net basolateral amino transport and thus the intracellular amino acid concentration. PMID:19184091

Verrey, François; Singer, Dustin; Ramadan, Tamara; Vuille-dit-Bille, Raphael N; Mariotta, Luca; Camargo, Simone M R

2009-01-28

41

2-amino-3-(oxirane-2,3-dicarboxamido)-propanoyl-valine, an effective peptide antibiotic from the epiphyte Pantoea agglomerans 48b/90.  

PubMed

The epiphyte Pantoea agglomerans 48b/90, which has been isolated from soybean leaves, belongs to the Enterobacteriaceae, as does the plant pathogen Erwinia amylovora, which causes fire blight on rosaceous plants such as apples and leads to severe economic losses. Since P. agglomerans efficiently antagonizes phytopathogenic bacteria, the P. agglomerans strain C9-1 is used as a biocontrol agent (BlightBan C9-1). Here we describe the bioassay-guided isolation of a peptide antibiotic that is highly active against the plant pathogen E. amylovora and pathovars of Pseudomonas syringae, and we elucidate its structure. Bioassay-guided fractionation using anion-exchange chromatography followed by hydrophobic interaction liquid chromatography yielded the bioactive, highly polar antibiotic. The compound was identified as 2-amino-3-(oxirane-2,3-dicarboxamido)-propanoyl-valine by using high-resolution electrospray ionization mass spectrometry and nuclear magnetic resonance techniques. This peptide was found to be produced by three of the nine P. agglomerans strains analyzed. Notably, the biocontrol strain P. agglomerans C9-1 also produces 2-amino-3-(oxirane-2,3-dicarboxamido)-propanoyl-valine. Previously, 2-amino-3-(oxirane-2,3-dicarboxamido)-propanoyl-valine has been characterized only from Serratia plymuthica. 2-Amino-3-(oxirane-2,3-dicarboxamido)-propanoyl-valine has been shown to inhibit the growth of the human pathogen Candida albicans efficiently, but its involvement in the defense of epiphytes against phytopathogenic bacteria has not been investigated so far. PMID:19820144

Sammer, Ulrike F; Völksch, Beate; Möllmann, Ute; Schmidtke, Michaela; Spiteller, Peter; Spiteller, Michael; Spiteller, Dieter

2009-10-09

42

OPTICAL ROTATORY DISPERSION OF SOME AMINO ACIDS AND CRITERIA OF PROTEIN CONFIGURATION  

Microsoft Academic Search

Rotatory dispersion of amino acids is well represented by a two-term ; Drude equation. The parameters of the equation are obtained by least-squares ; fitting with the aid of an electronic computer. using data for some 42 different ; wavelengths between 0.65 and 0.27 mu . Data are presented for the amino acids ; alanine, serine, valine, leucine, proline, aspartic

L. I. Katzin; E. Gulyas

1962-01-01

43

Free amino acid composition of Opisthorchis pedicellata (Trematoda) from the gall-bladder of a fresh water fish, Rita rita (Ham.)  

Microsoft Academic Search

Summary The paper chromatograms reveal the presence of 12 free amino acids, viz. leucine, isoleucine, valine, proline, tyrosine, phenyl-alanine, alanine, glycine, glutamic acid, serine, aspartic acid and lysine, in Opisthorchis pedicellata.

S. P. Gupta; Ramesh Chandra Gupta

1977-01-01

44

Formation of Meteoritic Amino Acids: Isovaline and its Isomers  

NASA Astrophysics Data System (ADS)

It has been known for several decades that amino acids, and other complex organics, are found in meteorites. In particular, Murchison (CM) samples contain over seventy amino acids, these being identified by high-level chromatographic methods. Among Murchison's amino acids, isovaline stands out as being both non-biological (non-protein) and having a relatively high abundance. While approximately equal amounts of D- and L- isovaline have been reported in Murchison and other CM meteorites, this molecule's structure appears to prohibit its racemization in aqueous solutions. We recently have investigated the low-temperature solid-phase chemistry of both isovaline and valine with an eye toward each molecule's formation, stability, and possible interconversions of their D and L enantiomers. Ion-irradiated isovalineand valine-containing ices were examined by IR spectroscopy and highly-sensitive liquid chromatography/time-of-flight mass spectral methods to assess both amino-acid destruction and racemization. Samples were studied in the presence and in the absence of water-ice, and the destruction of both isovaline and valine was measured as a function of radiation dose. In addition, we have synthesized isovaline, valine, and their amino acid isomers by solid-phase radiation-chemical pathways other than the oft-invoked Strecker process. This presentation will review and summarize some of our recent findings and place them in a context of related work. - Our work has been supported by a grant to the Goddard Center for Astrobiology through the NASA Astrobiology Institute. Experiments were performed in the Cosmic Ice Laboratory (RLH, MHM) and the Astrobiology Analytical Laboratory (JPD) at the NASA Goddard Space Flight Center.

Hudson, Reggie; Moore, Marla; Dworkin, Jason

45

Variation in amino acid composition of cytochrome c of species in the fungal genus Ustilago  

Microsoft Academic Search

Cytochrome c was extracted and purified from nine species of the genusUstilago, representing five pathogen for monocotyledonous and four for dicotyledonous host species. The amino acid compositions of acid hydrolysates of cytochrome c from these species were compared and divergence values were calculated for all pairs of species. Aspartic acid, serine, glutamic acid, proline, glycine, alanine, valine, leucine, phenylalanine, lysine,

Oscar H. Will III

1983-01-01

46

Some amino acids as corrosion inhibitors for copper in nitric acid solution  

Microsoft Academic Search

The inhibition effect of five amino acids (AA) on the corrosion of copper in molar nitric solution was studied by using weight loss and electrochemical polarization measurements. Valine (Val) and Glycine (Gly) accelerate the corrosion process; but Arginine (Arg), Lysine (Lys) and Cysteine (Cys) inhibit the corrosion phenomenon. Cysteine is the best inhibitor. Its efficiency increases with the concentration to

K. Barouni; L. Bazzi; R. Salghi; M. Mihit; B. Hammouti; A. Albourine; S. El Issami

2008-01-01

47

Transport of Amino Acids to the Maize Root 1  

PubMed Central

When 5-mm maize root tips were excised and placed in an inorganic salts solution for 6 hours, there was a loss of alcohol-insoluble nitrogen. The levels of threonine, proline, valine, isoleucine, leucine, tyrosine, phenylalanine, and lysine in the alcohol soluble fraction were severely reduced, whereas those of glutamate, aspartate, ornithine, and alanine were scarcely affected. There was a 4-fold increase in the level of ?-aminobutyrate. Those amino acids whose synthesis appeared to be deficient in excised root tips also showed poor incorporation of acetate carbon. In addition, the results show that asparagine and the amino acids of the neutral and basic fraction were preferentially transported to the root tip region. The results therefore suggest that the synthesis of certain amino acids in the root tip region is restricted, and that this requirement for amino acids in the growing region could regulate the flow of amino acids to the root tip.

Oaks, Ann

1966-01-01

48

Volume-regulatory Amino Acid Release from the Protozoan Parasite Crithidia luciliae  

Microsoft Academic Search

.   The unicellular protozoan parasite, Crithidia luciliae, responded to osmotic swelling by undergoing a regulatory volume decrease. This process was accompanied by the efflux of amino\\u000a acids (predominantly alanine, proline and glycine). The relative loss of the electroneutral amino acids proline, valine, alanine\\u000a and glycine was greater than that for the anionic amino acid, glutamate; there was negligible loss of

J. D. H. Bursell; J. Kirk; S. T. Hall; A. M. Gero; K. Kirk

1996-01-01

49

Transformation of some hydroxy amino acids to other amino acids.  

PubMed

It has been observed that beta-hydroxy-alpha-amino acids are transformed into other amino acids, when heated in dilute solutions with phosphorous acid, phosphoric acid or their ammonium salts. It has been shown that as in the case of previously reported glycine-aldehyde reactions, glycine also reacts with acetone to give beta-hydroxyvaline under prebiologically feasible conditions. It is suggested, therefore, that the formation of beta-hydroxy-alpha-amino acids and their transformation to other amino acids may have been a pathway for the synthesis of amino acids under primitive earth conditions. PMID:1208100

Choughuley, A S; Subbaraman, A S; Kazi, Z A; Chadha, M S

1975-10-01

50

CSF/plasma ratios of amino acids: Reference data and transports in children.  

PubMed

Objective: We intended to investigate the effects of age, gender, and medications on amino acid cerebrospinal fluid (CSF)/plasma ratios in children, and to determine whether amino acid transports across the blood-CSF barrier in children differ from those in adults. Patients and methods: Amino acid concentrations measured by ion-exchange high-performance liquid chromatography were used (CSF from 99 children, simultaneously collected plasma from 76 children). Influence of age, gender, and medications on the amino acid CSF concentrations and CSF/plasma ratios were analyzed by linear multiple regression. Interactions of amino acid transports were analyzed by correlation analysis of CSF/plasma ratios. Results: CSF/plasma ratios of serine, valine, histidine, and arginine were higher in younger children. The glutamate CSF/plasma ratio was higher in older children. Serine, alanine, threonine, valine, and histidine CSF/plasma ratios were lower in females. Glutamine, methionine, tyrosine, and phenylalanine CSF/plasma ratios were elevated with valproate therapy. Serine, threonine, valine, leucine, and tyrosine CSF/plasma ratios were lower with clobazam therapy. The asparagine CSF/plasma ratio was elevated with pyridoxal phosphate therapy. Transports of most essential neutral amino acids interacted with each other, as did neutral amino acids with low molecular weights. Cationic amino acids interacted with each other and some essential neutral amino acids. Acidic amino acids had no interactions with other amino acids. Conclusions: Age, gender, and anti-epileptic drugs affect amino acid CSF/plasma ratios in children. Transport interactions between amino acids in children showed no remarkable difference from those of adults and generally followed the substrate specificities of multiple amino acid transport systems. PMID:23287559

Akiyama, Tomoyuki; Kobayashi, Katsuhiro; Higashikage, Akihito; Sato, Junko; Yoshinaga, Harumi

2012-12-31

51

Uptake of free plasma amino acids by the lactating cow's udder and amino acid composition of udder lymph  

PubMed Central

1. Total ?-amino N and the amounts of 24 ninhydrin-positive substances were determined in several samples of plasma and lymph from the cow's udder. The arteriovenous differences of these substances across the mammary glands were measured in several experiments performed on lactating cows and in one experiment on a `dry' cow. Udder lymph obtained from live lactating cows by a lymph fistula and taken after killing lactating cows was analysed. 2. The concentrations of the individual free amino acids in udder lymph obtained from the live cow were similar to those found in cow's plasma. The concentrations of many amino acids in udder lymph taken immediately after death were two- to four-fold higher than those of the corresponding amino acids in udder lymph obtained from the live cow. 3. Most amino acids of the blood showed a considerable decrease in concentration by passage across the lactating mammary gland. Ornithine, a non-casein amino acid, showed arteriovenous differences of up to 60% of the arterial plasma concentration. No substantial amino acid uptake by the udder could be demonstrated in the experiment on the non-lactating cow. 4. The arteriovenous differences obtained for arginine, glutamine, isoleucine, leucine, lysine, valine, threonine and histidine were probably large enough to provide all the respective amino acid residues in milk protein. 5. The uptake of aspartic acid, asparagine, glutamic acid, serine and proline by the lactating cow's udder was not sufficient to account for all these respective amino acid residues found in milk protein.

Verbeke, R.; Peeters, G.

1965-01-01

52

Thirteen-Week Oral Toxicity Study of BranchedChain Amino Acids in Rats  

Microsoft Academic Search

Branched-chain amino acids (L-isoleucine, L-valine, and L-leucine) are being increasingly used in sport supplements. This study evaluated toxicological and behavioral effects of L-isoleucine (Ile), L-valine (Val), and L-leucine (Leu) during a dosing study with male and female Sprague-Dawley rats. The amino acids were incorporated into a standard diet at doses equal to 1.25%, 2.5%, and 5.0% (w\\/w). A control group

Shoji Tsubuku; Kazuhisa Hatayama; Toyohisa Katsumata; Nobuo Nishimura; Kazunori Mawatari; Miro Smriga; Takeshi Kimura

2004-01-01

53

Amino acids in Arctic aerosols  

NASA Astrophysics Data System (ADS)

Amino acids are significant components of atmospheric aerosols, affecting organic nitrogen input to marine ecosystems, atmospheric radiation balance, and the global water cycle. The wide range of amino acid reactivities suggest that amino acids may serve as markers of atmospheric transport and deposition of particles. Despite this potential, few measurements have been conducted in remote areas to assess amino acid concentrations and potential sources. Polar regions offer a unique opportunity to investigate atmospheric processes and to conduct source apportionment studies of such compounds. In order to better understand the importance of amino acid compounds in the global atmosphere, we determined free amino acids (FAAs) in seventeen size-segregated aerosol samples collected in a polar station in the Svalbard Islands from 19 April until 14 September 2010. We used an HPLC coupled with a tandem mass spectrometer (ESI-MS/MS) to analyze 20 amino acids and quantify compounds at fmol m-3 levels. Mean total FAA concentration was 1070 fmol m-3 where serine and glycine were the most abundant compounds in almost all samples and accounted for 45-60% of the total amino acid relative abundance. The other eighteen compounds had average concentrations between 0.3 and 98 fmol m-3. The higher amino acid concentrations were present in the ultrafine aerosol fraction (< 0.49 ?m) and accounted for the majority of the total amino acid content. Local marine sources dominate the boreal summer amino acid concentrations, with the exception of the regional input from Icelandic volcanic emissions.

Scalabrin, E.; Zangrando, R.; Barbaro, E.; Kehrwald, N. M.; Gabrieli, J.; Barbante, C.; Gambaro, A.

2012-11-01

54

Synthesis of amino acids  

DOEpatents

A method is described for synthesizing amino acids preceding through novel intermediates of the formulas: R/sub 1/R/sub 2/C(OSOC1)CN, R/sub 1/R/sub 2/C(C1)CN and (R/sub 1/R/sub 2/C(CN)O)/sub 2/SO wherein R/sub 1/ and R/sub 2/ are each selected from hydrogen and monovalent hydrocarbon radicals of 1 to 10 carbon atoms. The use of these intermediates allows the synthesis steps to be exothermic and results in an overall synthesis method which is faster than the synthesis methods of the prior art.

Davis, J.W. Jr.

1979-09-21

55

Global Expression Profiling and Physiological Characterization of Corynebacterium glutamicum Grown in the Presence of l-Valine  

PubMed Central

Addition of l-valine (50 to 200 mM) to glucose minimal medium had no effect on the growth of wild-type Corynebacterium glutamicum ATCC 13032 but inhibited the growth of the derived valine production strain VAL1 [13032 ?ilvA ?panBC(pJC1ilvBNCD)] in a concentration-dependent manner. In order to explore this strain-specific valine effect, genomewide expression profiling was performed using DNA microarrays, which showed that valine caused an increased ilvBN mRNA level in VAL1 but not in the wild type. This unexpected result was confirmed by an increased cellular level of the ilvB protein product, i.e., the large subunit of acetohydroxyacid synthase (AHAS), and by an increased AHAS activity of valine-treated VAL1 cells. The conclusion that valine caused the limitation of another branched-chain amino acid was confirmed by showing that high concentrations of l-isoleucine could relieve the valine effect on VAL1 whereas l-leucine had the same effect as valine. The valine-caused isoleucine limitation was supported by the finding that the inhibitory valine effect was linked to the ilvA deletion that results in isoleucine auxotrophy. Taken together, these results implied that the valine effect is caused by competition for uptake of isoleucine by the carrier BrnQ, which transports all branched-chained amino acids. Indeed, valine inhibition could also be relieved by supplementing VAL1 with the dipeptide isoleucyl-isoleucine, which is taken up by a dipeptide transport system rather than by BrnQ. Interestingly, addition of external valine stimulated valine production by VAL1. This effect is most probably due to a reduced carbon usage for biomass production and to the increased expression of ilvBN, indicating that AHAS activity may still be a limiting factor for valine production in the VAL1 strain.

Lange, C.; Rittmann, D.; Wendisch, V. F.; Bott, M.; Sahm, H.

2003-01-01

56

Free and Protein Amino Acid Composition of the Nematode (Toxascaris leonina) (Linstow, 1902) Occurring in the Red Fox (Vulpes vulpes)  

Microsoft Academic Search

The free and protein amino acids of Toxascaris leonina occurring in the red fox (Vulpes vulpes) were tentatively identified by the me:hod of descending two- dimensional paper chromatography. Lysine, histidine, arginne, glycine, senine, threonine, glutamic acid, alanine, proline, tyrosine, me:hionine, valine, phenyla- lanine, and leucine-isoleucine were found in the free amino acid fraction. The protein amino acid fraction revealed cystine,

W. G. DYER; D. F. BIBERDORF

57

Amino Acid Composition of Bulk Protein of Euglena Grown in Waste Water  

PubMed Central

The amino acid content of bulk protein in a sewage-grown Euglena sp. was examined. Concentrations of the essential amino acids, threonine, histidine, tryptophan, and valine, were similar to those found in other algae. The concentration of alanine was much higher. Methionine was not found at all, proline only in traces, and other amino acids at low concentrations. These results indicate that the amino acid content of bulk protein of the species of Euglena studied resembles that of plants far more closely than that of animals.

Kott, Yehuda; Wachs, A. M.

1964-01-01

58

Role of mitochondrial transamination in branched chain amino acid metabolism  

SciTech Connect

Oxidative decarboxylation and transamination of 1-/sup 14/C-branched chain amino and alpha-keto acids were examined in mitochondria isolated from rat heart. Transamination was inhibited by aminooxyacetate, but not by L-cycloserine. At equimolar concentrations of alpha-ketoiso(1-/sup 14/C)valerate (KIV) and isoleucine, transamination was increased by disrupting the mitochondria with detergent which suggests transport may be one factor affecting the rate of transamination. Next, the subcellular distribution of the aminotransferase(s) was determined. Branched chain aminotransferase activity was measured using two concentrations of isoleucine as amino donor and (1-/sup 14/C)KIV as amino acceptor. The data show that branched chain aminotransferase activity is located exclusively in the mitochondria in rat heart. Metabolism of extramitochondrial branched chain alpha-keto acids was examined using 20 microM (1-/sup 14/C)KIV and alpha-ketoiso(1-/sup 14/C)caproate (KIC). There was rapid uptake and oxidation of labeled branched chain alpha-keto acid, and, regardless of the experimental condition, greater than 90% of the labeled keto acid substrate was metabolized during the 20-min incubation. When a branched chain amino acid (200 microM) or glutamate (5 mM) was present, 30-40% of the labeled keto acid was transaminated while the remainder was oxidized. Provision of an alternate amino acceptor in the form of alpha-keto-glutarate (0.5 mM) decreased transamination of the labeled KIV or KIC and increased oxidation. Metabolism of intramitochondrially generated branched chain alpha-keto acids was studied using (1-/sup 14/C)leucine and (1-/sup 14/C)valine. Essentially all of the labeled branched chain alpha-keto acid produced by transamination of (1-/sup 14/C)leucine or (1-/sup 14/C)valine with a low concentration of unlabeled branched chain alpha-keto acid (20 microM) was oxidized.

Hutson, S.M.; Fenstermacher, D.; Mahar, C.

1988-03-15

59

Minimizing Amino Acid Catabolism Decreases Amino Acid Requirements1  

Microsoft Academic Search

The processes of natural selection shape the efficiency of nutrient use by animals, with some being especially thrifty while others are wasteful. An examination of the widely divergent amino acid economies of different species vividly illustrates this basic nutritional principle. The domestic cat evolved as a carnivore and has a very high maintenance requirement for dietary amino acids.The cat's veryhigh

Kirk C. Klasing

60

AUTORADIOGRAPHIC STUDY OF SUGAR AND AMINO ACID ABSORPTION BY EVERTED SACS OF HAMSTER INTESTINE  

Microsoft Academic Search

Autoradiographs were prepared from frozen sections of evcrted sacs of hamster jejunum which had been incubated in vitro with C 14- or H~-labcled sugars and amino acids. When such tissue was incubated in 1 mM solutions of L-valine or L-methionine, columnar absorp- tivc cells at tips of villi accumulated these amino acids to conccntrations ranging from 5 to 50 millimoles

WILLIAM B. KINTER; T. HASTINGS WILSON

1965-01-01

61

Free amino acids as energy substrate in developing eggs and larvae of the cod Gadus morhua  

Microsoft Academic Search

The content of free amino acids (FAA) in the cod (Gadus morhua L.) egg is about 200 nmol at spawning, decreasing by about 100 nmol\\/egg during the egg stage and about 75 nmol\\/larva during the yolksac larval stage. Together, alanine, leucine, serine, isoleucine, lysine, and valine account for about 75% of the decrease. Ammonium accumulates gradually during the egg stage

H. J. Fyhn; B. Serigstad

1987-01-01

62

Enantioselective self-assembly of antiferromagnetic hexacopper(II) wheels with chiral amino acid oxamates.  

PubMed

The Cu(2+)-mediated self-assembly of oxamato-based ligands derived from either the (S)- or (R)-enantiomers of the amino acid valine leads to the formation of two antiferromagnetically coupled homochiral anionic hexacopper(II) wheels in the presence of templating tetramethylammonium countercations. PMID:23715008

Grancha, Thais; Ferrando-Soria, Jesús; Cano, Joan; Lloret, Francesc; Julve, Miguel; De Munno, Giovanni; Armentano, Donatella; Pardo, Emilio

2013-07-01

63

Studies on Coordination Compounds of Organotin(IV) with Schiff Bases of Amino Acids  

Microsoft Academic Search

The present paper describes the syntheses, characterization of some new coordination compounds of organotin(IV) with Schiffbases derived by condensation of heterocyclic ketones and amino acids, viz. glycine, ?-alanine, ?-valine, ?-isoleucine and ?-tryptophan. The newely prepared compounds have been characterized by elemental analysis, conductance measurements, molecular weight determinations, infrared and nuclear magnatic resonance (H, C and Sn NMR) spectral studies. An

H. L. Singh; M. Sharma; A. K. Varshney

2000-01-01

64

Amino acids as natural inhibitors for hydrate formation in CO2 sequestration.  

PubMed

The motivation for this work was the potential of hydrophobic amino acids such as glycine, l-alanine, and l-valine to be applied as thermodynamic hydrate inhibitors (THIs). To confirm their capabilities in inhibiting the formation of gas hydrates, three-phase (liquid-hydrate-vapor) equilibrium conditions for carbon dioxide hydrate formation in the presence of 0.1-3.0 mol % amino acid solutions were determined in the range of 273.05-281.45 K and 14.1-35.2 bar. From quantitative analyses, the inhibiting effects of the amino acids (on a mole concentration basis) decreased in the following order: l-valine > l-alanine > glycine. The application of amino acids as THIs has several potential advantages over conventional methods. First, the environmentally friendly nature of amino acids as compared to conventional inhibitors means that damage to ecological systems and the environment could be minimized. Second, the loss of amino acids in recovery process would be considerably reduced because amino acids are nonvolatile. Third, amino acids have great potential as a model system in which to investigate the inhibition mechanism on the molecular level, since the structure and chemical properties of amino acids are well understood. PMID:21663046

Sa, Jeong-Hoon; Lee, Bo Ram; Park, Da-Hye; Han, Kunwoo; Chun, Hee Dong; Lee, Kun-Hong

2011-06-10

65

Amino Acid capture by aqueous interfaces. Implications for biological uptake.  

PubMed

The interactions of natural amino acids with water-hydrophobic interfaces are central to the control of key biological processes, such as passive transport, and to the overall structure and stability of membrane proteins. We still have a very poor knowledge of these interactions, and our aim in this work is to investigate the thermochemistry and dynamics properties of simple aliphatic amino acids (glycine and valine) across a water-organic interface. The study has been carried out by means of Born-Oppenheimer molecular dynamics simulations focusing on the role that the hydrophobicity of the side chain has on the phase transfer mechanism of the amino acid. Data for the energetics of the uptake processes have been reported, and it is expected that the reported results will be helpful in the design of future experiments with systems of biological relevance. We have shown that neutral tautomers exhibit a noticeable affinity for the interface that increases with increasing hydrophobicity of the side chain. Moreover, the zwitterionic form of valine (but not that of glycine) does also exhibit a significant affinity for the interface. An important finding is that the neutral and zwitterionic tautomers are roughly isoergonic in the organic layer close to the interface. This result suggests a two-step mechanism for the water-to-organic phase transfer that involves neutralization of a partially hydrated zwitterion in the organic layer prior to uptake into the bulk. Though the mechanisms for glycine and valine are similar, the predicted energetics and dynamics for the first step display noteworthy differences that should be measurable and may have important biological implications. PMID:24093882

Martins-Costa, Marilia T C; Ruiz-Lopez, Manuel F

2013-10-04

66

Effects of running the Boston marathon on plasma concentrations of large neutral amino acids.  

PubMed

Plasma large neutral amino acid concentrations were measured in thirty-seven subjects before and after completing the Boston Marathon. Concentrations of tyrosine, phenylalanine, and methionine increased, as did their "plasma ratios" (i.e., the ratio of each amino acid's concentration to the summed plasma concentrations of the other large neutral amino acids which compete with it for brain uptake). No changes were noted in the plasma concentrations of tryptophan, leucine, isoleucine, nor valine; however, the "plasma ratios" of acid patterns may influence neurotransmitter synthesis. PMID:2708978

Conlay, L A; Wurtman, R J; Lopez G-Coviella, I; Blusztajn, J K; Vacanti, C A; Logue, M; During, M; Caballero, B; Maher, T J; Evoniuk, G

1989-01-01

67

Regulation of valine and. alpha. -ketoisocaproate metabolism in rat kidney mitochondria  

SciTech Connect

Activities of branched-chain amino acid (BCAA) aminotransferase (BCAT) and {alpha}-keto acid dehydrogenase (BCKD) were assayed in mitochondria isolated from kidneys of rats. Rates of transamination of valine and oxidation of keto acids {alpha}-ketoisocaproate (KIC) or {alpha}-ketoisovalerate (KIV) were estimated using radioactive tracers of the appropriate substrate from amounts of {sup 14}C-labeled products formed. Because of the high mitochondrial BCAT activity, an amino acceptor for BCAT, {alpha}-ketoglutarate ({alpha}-KG) or KIC, was added to the assay medium when valine was the substrate. Rates of valine transamination and subsequent oxidation of the KIV formed were determined with 0.5 mM {alpha}-KG as the amino acceptor; these rates were 5- to 50-fold those without added {alpha}-KG. Rates of CO{sub 2} evolution from valine also increased when KIC was present; however, with KIC concentrations above 0.2 mM, rates of CO{sub 2} evolution from valine declined although rates of transamination continued to rise. When 0.05 mM KIC was added to the assay medium, oxidation of KIC was suppressed by inclusion of valine or glutamate in the medium. When valine was present KIC was not oxidized preferentially, presumably because it was also serving as an amino acceptor for BCAT. These results indicate that as the supply of amino acceptor, {alpha}-KG or KIC, is increased in mitochondria not only is the rate of valine transamination stimulated but also the rate of oxidation of the KIV formed from valine. Thus the rate of oxidation of BCAA can be controlled by factors that influence the rate and direction of BCAA transamination and, thereby, the supply of substrate for BCKD.

Miller, R.H.; Harper, A.E. (Univ. of Wisconsin, Madison (USA))

1988-10-01

68

The relationship between the biosynthetic paths to the amino acids and their coding  

NASA Astrophysics Data System (ADS)

The genetic code could not have been fixed until the means for biosynthesis of the amino acids was at hand. The biosynthetic enzymes could not be optimized until the genetic code ceased to be rearranged. Therefore the development of the code and the development of the biosynthesis of the amino acids occurred concurrently. The present day biosynthetic pathways of amino acids, examined from this point of view, help to explain the present set of coded amino acids, in particular the absence of norvaline, norleucine, homoserine, ornithine, and alpha-aminobutyric acid. An order of development of biosyntheses is also proposed. Lysine was first, followed by valine and isoleucine. The more common primordial amino acids did not need biosyntheses so early. The central pathways of metabolism probably developed in response to a need for amino acid biosynthesis.

McClendon, John H.

1987-09-01

69

Influence of leucine infusion on intracellular amino acids in humans.  

PubMed

A continuous intravenous infusion of L-leucine (300 mumols min-1) was given to 12 healthy females over a 2 1/2 h period. Arterial plasma concentrations of amino acids and the keto acids of the branched-chain amino acids (BCAA) were measured. In six subjects muscle biopsies were taken before and at the end of the infusion for determination of intracellular (i.c.) free amino acid concentrations, and leg exchange of amino acids was measured. During infusion the plasma level of leucine rose sixfold. Approximately 40% of the infused amount was taken up by muscle. Of this, half was accumulated intracellularly, where the free leucine concentration increased from basal 190 +/- 22 to 580 +/- 110 mumols l-1 ICW (intracellular water) at the end of infusion. The concentrations of most other amino acids, above all the other BCAA and the aromatic amino acids, decreased, by 17-48% in the i.c. pool and by 17-79% in plasma. The plasma level of ketoisocaproic acid (KIC), the keto acid of leucine, increased in parallel with that of leucine. The concentration of keto valine, ketoisovaleric acid (KIV), decreased by 75%, whereas the keto acid of isoleucine, ketomethylvaleric acid (KMV), was unchanged. Leg release of alanine decreased significantly, whereas the exchange of other amino acids were unchanged. Taken together, decreased i.c. and plasma concentrations but unchanged leg exchange of tyrosine and phenylalanine suggest i.c. accumulation of protein. It can be calculated that approximately 40% of the leucine taken up by muscle was accumulated in the intracellular free pool, some 20% could have been incorporated into protein and 40% was probably oxidized. PMID:2114990

Alvestrand, A; Hagenfeldt, L; Merli, M; Oureshi, A; Eriksson, L S

1990-06-01

70

Raman spectra of amino acids and their aqueous solutions  

NASA Astrophysics Data System (ADS)

Amino acids are the basic "building blocks" that combine to form proteins and play an important physiological role in all life-forms. Amino acids can be used as models for the examination of the importance of intermolecular bonding in life processes. Raman spectra serve to obtain information regarding molecular conformation, giving valuable insights into the topology of more complex molecules (peptides and proteins). In this paper, amino acids and their aqueous solution have been studied by Raman spectroscopy. Comparisons of certain values for these frequencies in amino acids and their aqueous solutions are given. Spectra of solids when compared to those of the solute in solution are invariably much more complex and almost always sharper. We present a collection of Raman spectra of 18 kinds of amino acids ( L-alanine, L-arginine, L-aspartic acid, cystine, L-glutamic acid, L-glycine, L-histidine, L-isoluecine, L-leucine, L-lysine, L-phenylalanine, L-methionone, L-proline, L-serine, L-threonine, L-tryptophan, L-tyrosine, L-valine) and their aqueous solutions that can serve as references for the interpretation of Raman spectra of proteins and biological materials.

Zhu, Guangyong; Zhu, Xian; Fan, Qi; Wan, Xueliang

2011-03-01

71

Amino Acid Composition and Terminal Amino Acids of Staphylococcal Enterotoxin B.  

National Technical Information Service (NTIS)

The amino acid composition of purified staphylococcal enterotoxin B was determined by means of an automatic amino acid analyzer. All of the naturally occurring amino acids were found with no indication of any unusual amino acids. Extraordinarily high valu...

L. Spero D. Stefanye P. I. Brecher H. M. Jacoby E. J. Schantz

1964-01-01

72

IS VALINE LIMITING IN BROILER GROWTH DIETS BASED ON CORN AND SOYBEAN MEAL  

Technology Transfer Automated Retrieval System (TEKTRAN)

Broiler diets formulated to contain crystalline L-Thr when priced below the shadow value, in addition to synthetic Met and crystalline Lys, allow for more efficient amino acid utilization. However, minimums for the less limiting amino acids become more critical. Valine has not been researched to t...

73

Uptake of dissolved free amino acids by spiny lobster Panulirus japonicus phyllosoma larvae  

Microsoft Academic Search

This study examined the ability of late stage (instar XXVI) Japanese spiny lobster Panulirus japonicus phyllosoma larvae to uptake seven l-type amino acids (AAs; aspartic acid, Asp; threonine, Thr; glutamic acid, Glu; glycine, Gly; alanine, Ala; valine, Val; and\\u000a methionine, Met) from the rearing medium. The time course uptake during incubation for 5 h in solutions containing 1, 2, 5,\\u000a 10,

Samet Can Söylemez; Keisuke Murakami; Carlos Augusto Strüssmann; Masashi Yokota; Seiichi Watanabe

2010-01-01

74

Pseudo-poly(amino acid)s: study on construction and characterization of novel chiral and thermally stable nanostructured poly(ester-imide)s containing different trimellitylimido-amino acid-based diacids and pyromellitoyl-tyrosine-based diol  

Microsoft Academic Search

A new class of chiral and potentially biodegradable poly(ester-imide)s (PEI)s as pseudo-poly(amino acid)s (PAA)s bearing natural\\u000a amino acids in the main chain was synthesized. In this investigation, N,N?-(pyromellitoyl)-bis-(L-tyrosine dimethyl ester) as a biodegradable optically active diphenol and synthesized trimellitic\\u000a anhydride-derived dicarboxylic acids containing different natural amino acids such as S-valine, L-methionine, L-leucine, L-isoleucine,\\u000a and L-phenylalanine were used for direct polyesterification.

Shadpour Mallakpour; Fatemeh Zeraatpisheh

2011-01-01

75

Disorders of Amino Acid Metabolism  

MedlinePLUS

... dialysis (see Dialysis ). Some children with mild disease benefit from injections of vitamin B 1 (thiamin). After the disease has been brought under control, children must always consume a special artificial diet that is low in three amino acids ( ...

76

Spectroscopic studies of amino acid ionic liquid-supported Schiff bases.  

PubMed

Amino acid ionic liquid-supported Schiff bases, derivatives of salicylaldehyde and various amino acids (L-threonine, L-valine, L-leucine, L-isoleucine and L-histidine) have been investigated by means of various spectroscopic techniques (NMR, UV-Vis, IR, MS) and deuterium isotope effects on ¹³C-NMR chemical shifts. The results have shown that in all studied amino acid ionic liquid-supported Schiff bases (except the L-histidine derivative) a proton transfer equilibrium exists and the presence of the COO? group stabilizes the proton transferred NH-form. PMID:23629755

Ossowicz, Paula; Janus, Ewa; Schroeder, Grzegorz; Rozwadowski, Zbigniew

2013-04-29

77

Amino Acids and the Mitochondria  

Microsoft Academic Search

\\u000a This chapter describes some of the important physiological functions of amino acids in the mitochondria and the alterations\\u000a caused by specific pathologies. To some extent all of the featured items are dependent upon the movement of amino acids across\\u000a the highly selective permeability barrier that is the inner mitochondrial membrane. The performance of this transport by specific\\u000a carriers is the

Nicola King

78

Hydrothermal synthesis of amino acids  

SciTech Connect

This study presents further evidence that amino acids can be synthesized rapidly in hydrothermal solutions from reactants that may have been present in primitive environments. Aqueous NH[sub 4]HCO[sub 3] solutions were reacted with C[sub 2]H[sub 2], H[sub 2], and O[sub 2] (formed in situ from CaC[sub 2], Ca, and H[sub 2]O[sub 2]) at 200-275[degrees]C over 0.2-2 h periods to synthesize several amino acids and abundant amines. These amino acid and amine producing reactions were not observed to occur below 150[degrees]C. Amino acids and amines also were synthesized at 210[degrees]C from solutions of NH[sub 4]OH, HCHO, NaCN, and H[sub 2]. When NH[sub 4]OH was replaced by NH[sub 4]HCO[sub 3], the syntheses predominantly confirmed the recent results of Hennet et al. (1992). Additionally, amino acids and amines were observed to form by reactions among NH[sub 4]OH, HCHO, and H[sub 2] at hydrothermal conditions, essentially confirming the results of Fox and Windsor (1970). Inclusion of both carbonate and O[sub 2] in these latter solutions greatly enhanced the production rate of amino acids. The amines synthesized hydrothermally could be significant if they are precursors in the amino acid syntheses either at hydrothermal or later at lower temperatures. These observations provide additional input to the current questions of synthesis, stability, and decomposition of amino acids at hydrothermal conditions, and their possible relevance to the origin of life.

Marshall, W.L. (Oak Ridge National Lab., TN (United States))

1994-05-01

79

Induced Phenotypic Resistance to Valine in Mycobacterium pellegrino  

PubMed Central

Valine coordinately increases the levels of three of the enzymes participating in the biosynthesis of isoleucine and valine in Mycobacterium pellegrino. The amount of valine required for end-product induction depends on the condition of the cells. Isoleucine inhibits the effect of valine. Acetohydroxy acid synthetase, the enzyme catalyzing the first common step in the biosynthesis of valine and isoleucine, is inhibited by valine. The induction effect of valine appears to be due to its ability to inhibit the activity of this enzyme, thus causing isoleucine deficiency, which in turn leads to derepression. This conclusion is supported by the fact that valine, under certain conditions, inhibits growth.

Horvath, Istvan; Szentirmai, A.; Zsadanyi, J.

1967-01-01

80

Amino acids and cell regulation.  

PubMed Central

Free amino play an important role in regulating cell volume in fishes. Four tissues/cells (skeletal muscle, RBC, brain, and myocardium) of the little skate, Raja erinacea, were selected for detailed study because of their special importance or unique advantage as experimental models. Three particular amino acids, beta-alanine, taurine, and sarcosine play a predominant role in all four tissues. As in higher vertebrates, amino acid uptake in skate brain, heart, and RBC is mediated via a Na+-dependent process. Amino acids leave the skate brain rapidly in response to a sudden decrease in plasma osmolality and/or to a simultaneous drop in extracellular Na+ concentration. However, although amino acids are important for volume regulation in normal brain cells, they do not appear to be likely candidates for the unidentified "idiogenic" osmolytes in mammalian brain cells. The high concentration of taurine in skate myocardium is of special interest because of the special role of this amino acid in myocardial contractility. Thus, unlike beta-alanine and sarcosine, taurine may play a dual role in regulating both cell volume and contractility of myocardial cells. The isolated skate atrium is well suited for in vitro studies of these two processes.

Forster, R. P.; Goldstein, L.

1979-01-01

81

Amino acids conferring herbicide resistance in tobacco acetohydroxyacid synthase.  

PubMed

Acetohydroxyacid synthase (AHAS) (EC 4.1.3.18) is a target of commercially available herbicides such as sulfonylurea, imidazolinone, and triazolopyrimidine. In plants and microorganisms, AHAS catalyzes the first common reaction in the biosynthesis pathways leading to leucine, isoleucine and valine. Intensive studies using different approaches - including site-directed mutagenesis, molecular modeling and structural analysis - on plant AHAS-s have contributed to the understanding of the herbicide-AHAS interaction. Knowledge of the critical roles of amino acid residues of plant AHAS in conferring herbicide resistance will enable the creation of new herbicide-tolerant AHAS which could be used to develop herbicide-resistant transgenic plants. Moreover, such information will also elucidate design strategies for more efficient herbicides that could also kill weeds resistant to previously used AHAS-inhibiting herbicides. In this review, we summarize the results of intensive searches for amino acid residues and their substitutions that confer herbicide resistance in tobacco AHAS. PMID:21865873

Le, Dung Tien; Choi, Jung-Do; Tran, Lam-Son Phan

82

Intermolecular vibrations in hydrophobic amino Acid crystals: experiments and calculations.  

PubMed

Intermolecular vibrations of amino acid crystals occur in the THz, or far-infrared, region of the electromagnetic spectrum. We have measured the THz and Raman spectra of dl-leucine as well as two polymorphs of dl-valine, the spectroscopic properties of which have not previously been compared. Theoretical modeling of intermolecular vibrations in hydrophobic amino acids is challenging because the van der Waals interactions between molecules are not accounted for in standard density functional theory. Therefore, to calculate the vibrational modes, we used a recently developed approach that includes these nonlocal electron correlation forces. We discuss methods for comparing results from different theoretical models using metrics other than calculated vibrational frequency and intensity, and we also report a new approach enabling concise comparison of vibrational modes that involve complicated mixtures of inter- and intramolecular displacements. PMID:23931283

Williams, Michael R C; Aschaffenburg, Daniel J; Ofori-Okai, Benjamin K; Schmuttenmaer, Charles A

2013-08-28

83

Assessment of the relevance of the antibiotic 2-amino-3-(oxirane-2,3-dicarboxamido)-propanoyl-valine from Pantoea agglomerans biological control strains against bacterial plant pathogens.  

PubMed

The epiphyte Pantoea agglomerans 48b/90 (Pa48b) is a promising biocontrol strain against economically important bacterial pathogens such as Erwinia amylovora. Strain Pa48b produces the broad-spectrum antibiotic 2-amino-3-(oxirane-2,3-dicarboxamido)-propanoyl-valine (APV) in a temperature-dependent manner. An APV-negative mutant still suppressed the E. amylovora population and fire blight disease symptoms in apple blossom experiments under greenhouse conditions, but was inferior to the Pa48b wild-type indicating the influence of APV in the antagonism. In plant experiments with the soybean pathogen Pseudomonas syringae pv. glycinea both, Pa48b and the APV-negative mutant, successfully suppressed the pathogen. Our results demonstrate that the P. agglomerans strain Pa48b is an efficient biocontrol organism against plant pathogens, and we prove its ability for fast colonization of plant surfaces over a wide temperature range. PMID:23233458

Sammer, Ulrike F; Reiher, Katharina; Spiteller, Dieter; Wensing, Annette; Völksch, Beate

2012-10-30

84

Micro determination of ?-amino-acids through chelation with copper and titration with EDTA  

Microsoft Academic Search

Summary A complexometric method was developed for the microdetermination ofa-amino-acids that form soluble copper complexes. The method is based upon reaction with cupric phosphate suspension, isolation of the Cu-complex, its oxidative destruction with conc. nitric acid, evaporation, and titration of the cupric nitrate at pH 7–8 with EDTA in presence of murexide as indicator. Glycine, alanine, valine, tyrosine, serine, histidine-HCl,

Y. A. Gawargious; Amir Besada; M. E. M. Hassouna

1974-01-01

85

Digestible amino acids for poultry and swine  

Microsoft Academic Search

A review and comparison of feedstuff amino acid digestibility values for poultry and swine is presented and the use of amino acid digestibility and availability is discussed. The effect of overprocessing on amino acid digestibility of oilseed meals is also reviewed. In general, true digestible amino acid values determined in cecectomized roosters are 5–10% higher than apparent digestibility values determined

Carl M. Parsons

1996-01-01

86

Role of transport systems in amino acid metabolism: leucine toxicity and the branched-chain amino acid transport systems.  

PubMed Central

The livR locus, which leads to a trans-recessive derepression of branched-chain amino acid transport and periplasmic branched-chain amino acid-binding proteins, is responsible for greatly increased sensitivity toward growth inhibition by leucine, valine, and serine and, as shown previously, for increased sensitivity toward toxicity by branched-chain amino acid analogues, such as 4-azaleucine or 5',5',5'-trifluoroleucine. These phenotypes are similar to those of relA mutants; however, the livR mutants retain the stringent response of ribonucleic acid synthesis. However, an increase in the rate of transport or in the steady-state intracellular level of amino acids in the livR strain cannot completely account for this sensitivity. The ability of the LIV-I transport system to carry out exchange of pool amino acids for extracellular leucine is a major factor in leucine sensitivity. The previous finding that inhibition of threonine deaminase by leucine contributes to growth inhibition is confirmed by simulating the in vivo conditions using a toluene-treated cell preparation with added amino acids at levels corresponding to the internal pool. The relationship between transport systems and corresponding biosynthetic pathways is discussed and the general principle of a coordination in the regulation of transport and biosynthetic pathways is forwarded. The finding that the LIV-I transport system functions well for amino acid exchange in contrast to the LIV-II system provides another feature that distinguishes these systems in addition to previously described differences in regulation and energetics.

Quay, S C; Dick, T E; Oxender, D L

1977-01-01

87

Amino acid losses during hemodialysis with infusion of amino acids and glucose  

Microsoft Academic Search

Amino acid losses during hemodialysis with infusion of amino acids and glucose. This study evaluated the effects during hemodialysis of intravenous infusion of amino acids and glucose on plasma amino acid and glucose concentrations and amino acid losses. Eight men undergoing maintenance hemodialysis were each studied during two dialyses using glucose-free dialysate. During one hemodialysis, they were infused with 800

Marsha Wolfson; Michael R Jones; Joel D Kopple

1982-01-01

88

Reactions of Chelates with Macrocyclic Ligands. Complexation between Tetraphenylporphine and Cu(II) Complexes with ?-Amino Acids  

Microsoft Academic Search

The reactions of tetraphenylporphine (H2TPP) with copper(II) chelates in DMSO were studied. a-Amino acids (glycine, a-alanine, valine, leucine, tyrosine, and glutamine) were used as chelating ligands. The study of the reaction kinetics showed that Cu(II) chelates with alanine and the other amino acids are less reactive in these reactions than acetylacetonates, a-nitroso-ß-naphtholates, and hydroxyquinolates. The exception is a Cu(II) complex

B. D. Berezin; G. M. Mamardashvili

2002-01-01

89

Branched-Chain Amino Acid Metabolism in Arabidopsis thaliana  

PubMed Central

Valine, leucine and isoleucine form the small group of branched-chain amino acids (BCAAs) classified by their small branched hydrocarbon residues. Unlike animals, plants are able to de novo synthesize these amino acids from pyruvate, 2-oxobutanoate and acetyl-CoA. In plants, biosynthesis follows the typical reaction pathways established for the formation of these amino acids in microorganisms. Val and Ile are synthesized in two parallel pathways using a single set of enzymes. The pathway to Leu branches of from the final intermediate of Val biosynthesis. The formation of this amino acid requires a three-step pathway generating a 2-oxoacid elongated by a methylene group. In Arabidopsis thaliana and other Brassicaceae, a homologous three-step pathway is also involved in Met chain elongation required for the biosynthesis of aliphatic glucosinolates, an important class of specialized metabolites in Brassicaceae. This is a prime example for the evolutionary relationship of pathways from primary and specialized metabolism. Similar to animals, plants also have the ability to degrade BCAAs. The importance of BCAA turnover has long been unclear, but now it seems apparent that the breakdown process might by relevant under certain environmental conditions. In this review, I summarize the current knowledge about BCAA metabolism, its regulation and its particular features in Arabidopsis thaliana.

Binder, Stefan

2010-01-01

90

The synthesis of amino acids by Methanobacterium omelianskii  

PubMed Central

1. Methanobacterium omelianskii was grown on 14CO2 and unlabelled ethanol, or on [1-14C]- or [2-14C]-ethanol and unlabelled carbon dioxide. The cell protein was hydrolysed and certain of the amino acids were isolated and degraded. 2. Carbon from both carbon dioxide and ethanol is used for biosynthesis of amino acids, and in most cases ethanol is incorporated as a C2 unit. Ethanol carbon atoms and carbon dioxide carbon atoms apparently enter the same range of compounds. Ethanol and carbon dioxide are equally important as sources of cell carbon. 3. The origins of carbon atoms of aspartate, alanine, glycine, serine and threonine are consistent with the synthesis of these amino acids, by pathways known to exist in aerobic organisms, from pyruvate arising by a C2+C1 condensation. The proportion of total radioactivity found in C-1 of lysine, proline, methionine and valine is consistent with synthesis of these amino acids by pathways similar to those found in Escherichia coli. Isoleucine is probably formed by carboxylation of a C5 precursor formed entirely from ethanol. Glutamate is formed by an unknown pathway.

Knight, M.; Wolfe, R. S.; Elsden, S. R.

1966-01-01

91

Arachnid relationships based on mitochondrial genomes: asymmetric nucleotide and amino acid bias affects phylogenetic analyses.  

PubMed

Phylogenetic analyses based on mitochondrial DNA have yielded widely differing relationships among members of the arthropod lineage Arachnida, depending on the nucleotide coding schemes and models of evolution used. We enhanced taxonomic coverage within the Arachnida greatly by sequencing seven new arachnid mitochondrial genomes from five orders. We then used all 13 mitochondrial protein-coding genes from these genomes to evaluate patterns of nucleotide and amino acid biases. Our data show that two of the six orders of arachnids (spiders and scorpions) have experienced shifts in both nucleotide and amino acid usage in all their protein-coding genes, and that these biases mislead phylogeny reconstruction. These biases are most striking for the hydrophobic amino acids isoleucine and valine, which appear to have evolved asymmetrical exchanges in response to shifts in nucleotide composition. To improve phylogenetic accuracy based on amino acid differences, we tested two recoding methods: (1) removing all isoleucine and valine sites and (2) recoding amino acids based on their physiochemical properties. We find that these methods yield phylogenetic trees that are consistent in their support of ancient intraordinal divergences within the major arachnid lineages. Further refinement of amino acid recoding methods may help us better delineate interordinal relationships among these diverse organisms. PMID:18992830

Masta, Susan E; Longhorn, Stuart J; Boore, Jeffrey L

2008-11-01

92

Acetohydroxy acid synthase I, a required enzyme for isoleucine and valine biosynthesis in Escherichia coli K-12 during growth on acetate as the sole carbon source.  

PubMed Central

Escherichia coli K-12 has two acetohydroxy acid synthase (AHAS) isozymes (AHAS I and AHAS III). Both of these isozymes catalyze the synthesis of alpha-aceto-alpha-hydroxybutyrate and alpha-acetolactate, which are key intermediates of the isoleucine-valine biosynthetic pathway. Strains lacking either isozyme but not both activities have been previously shown to grow well in minimal media in the absence of isoleucine and valine on any of several commonly used carbon sources (e.g., glucose or succinate). We report the characterization of mutants that were unable to grow on either acetate or oleate as a sole carbon source due to a defect in isoleucine-valine biosynthesis. The defect in isoleucine-valine biosynthesis was expressed only on these carbon sources and was due to the loss of AHAS I activity, resulting from lesions in the ilvBN operon. Previously identified ilvBN mutant strains also failed to grow on acetate or oleate minimal media. Our results indicated that AHAS I is an essential enzyme for isoleucine and valine biosynthesis when E. coli K-12 is grown on acetate or oleate as the sole carbon source. AHAS III was expressed during growth on acetate or oleate but was somehow unable to produce sufficient amounts of alpha-aceto-alpha-hydroxybutyrate and alpha-acetolactate to allow growth.

Dailey, F E; Cronan, J E

1986-01-01

93

The effect of changing environmental salinity on the free amino-acid composition of an estuarine population of Neomysis integer  

Microsoft Academic Search

An estuarine population of Neomysis integer was exposed under continuous laboratory conditions to changes in salinity equivalent to the type of tidal change to which they were normally exposed. The resultant changes in the concentrations of their free amino acids were compared. Glycine, alanine, proline, glutamate and valine increased as salinity increased and time-course experiments showed that these changes occurred

M. E. Armitage; R. J. Morris

1982-01-01

94

Branched-chain amino acid metabolism and alanine formation in rat diaphragm muscle in vitro. Effects of dichloroacetate.  

PubMed Central

Dichloroacetate (which activates pyruvate dehydrogenase) decreases the release of alanine, pyruvate and lactate in hemidiaphragm incubations with valine. Dichloroacetate interferes with alanine formation by diverting pyruvate into oxidative pathways, which not only limits pyruvate availability for direct transamination to form alanine but also indirectly affects branched-chain amino acid transamination by limiting 2-oxoglutarate regeneration from glutamate.

Snell, K; Duff, D A

1984-01-01

95

Modeling mammary amino acid metabolism  

Microsoft Academic Search

Milk pricing schemes place economic importance on milk components. Most current nutrient requirement models do not predict milk component yields accurately. Deaggregation of energy and protein terms in those models may improve prediction accuracy. Descriptions of energy metabolism by the major postabsorptive tissues have progressed over the last 20 years. More recent efforts have been directed at representing amino acid

Mark D. Hanigan; Brian J. Bequette; Les A. Crompton; James France

2001-01-01

96

PLASMA PROTEIN PRODUCTION INFLUENCED BY AMINO ACID MIXTURES AND LACK OF ESSENTIAL AMINO ACIDS  

PubMed Central

When blood plasma proteins are depleted by bleeding with return of red cells suspended in saline (plasmapheresis) it is possible to bring dogs to a steady state of hypoproteinemia and a constant level of plasma protein production if the diet nitrogen intake is controlled and limited. Such dogs are outwardly normal but have a lowered resistance to infection and intoxication and probably to vitamin deficiency. When the diet nitrogen is provided by certain mixtures of the ten growth essential amino acids plus glycine, given intravenously at a rapid rate, plasma protein production is good. The same mixture absorbed subcutaneously at a slower rate may be slightly better utilized. Fed orally the same mixture is better utilized and associated with a lower urinary nitrogen excretion. An ample amino acid mixture for the daily intake of a 10 kilo dog may contain in grams dl-threonine 1.4, dl-valine 3, dl-leucine 3, dl-isoleucine 2, l(+)-lysine·HCl·H2O 2.2, dl-tryptophane 0.3, dl-phenylalanine 2, dl-methionine 1.2, l(+)-histidine·HCl·H2O 1, l(+)-arginine·HCl 1, and glycine 2. Half this quantity is inadequate and not improved by addition of a mixture of alanine, serine, norleucine, proline, hydroxyproline, and tyrosine totalling 1.4 gm. Aspartic acid appears to induce vomiting when added to a mixture of amino acids. The same response has been reported for glutamic acid (8). Omission from the intake of leucine or of leucine and isoleucine results in negative nitrogen balance and rapid weight loss but plasma protein production may be temporarily maintained. It is possible that leucine may be captured from red blood cell destruction. Tryptophane deficiency causes an abrupt decline in plasma protein production. No decline occurred during 2 weeks of histidine deficiency but the urinary nitrogen increased to negative balance. Plasma protein production may be impaired during conditions of dietary deficiency not related to the protein or amino acid intake. Skin lesions and liver function impairment are described. Unidentified factors present in liver and yeast appear to be involved.

Madden, S. C.; Anderson, F. W.; Donovan, J. C.; Whipple, G. H.

1945-01-01

97

Transport of Amino Acids in Lactobacillus casei by Proton-Motive-Force-Dependent and Non-Proton-Motive-Force-Dependent Mechanisms  

Microsoft Academic Search

Lactobacilus casei 393 cells which were energized with glucose (pH 6.0) took up glutamine, asparagine, glutamate, aspartate, leucine, and phenylalanine. Little or no uptake of several essential amino acids (valine, isoleucine, arginine, cysteine, tyrosine, and tryptophan) was observed. Inhibition studies indicated that there were at least five amino acid carriers, for glutamine, asparagine, glutamate\\/aspartate, phenylalanine, or branched-chain amino acids. Transport

Herbert J. Strobel; James B. Russell; Arnold J. M. Driessen; Wil N. Konings

1989-01-01

98

Amino Acid and Protein Metabolism in Bermuda Grass During Water Stress 12  

PubMed Central

The ability of Arizona Common and Coastal Bermuda grass [Cynodon dactylon (L.) Pers.] to synthesize amino acids and proteins during water stress was investigated. Amino acids were continually synthesized during the water stress treatments, but protein synthesis was inhibited and protein levels decreased. Water stress induced a 10- to 100-fold accumulation of free proline in shoots and a 2- to 6-fold accumulation of free asparagine, both of which are characteristic responses of water-stressed plants. Valine levels increased, and glutamic acid and alanine levels decreased. 14C labeling experiments showed that free proline turns over more slowly than any other free amino acid during water stress. This proline is readily synthesized and accumulated from glutamic acid. It is suggested that during water stress free proline functions as a storage compound. No significant differences were found in the amino acid and protein metabolism of the 2 varieties of Bermuda grass.

Barnett, N. M.; Naylor, A. W.

1966-01-01

99

Adenosine 5?-Triphosphate-Yielding Pathways of Branched-Chain Amino Acid Fermentation by a Marine Spirochete  

PubMed Central

The metabolic pathways utilized by an obligately anaerobic marine spirochete (strain MA-2) to ferment branched-chain amino acids were studied. The spirochete catabolized l-leucine to isovaleric acid, l-isoleucine to 2-methylbutyric acid, and l-valine to isobutyric acid, with accompanying CO2 production in each fermentation. Cell extracts of spirochete MA-2 converted l-leucine, l-isoleucine, and l-valine to 2-ketoisocaproic, 2-keto-3-methylvaleric, and 2-ketoisovaleric acids, respectively, through mediation of 2-ketoglutarate-dependent aminotransferase activities. The branched-chain keto acids were decarboxylated and oxidized to form isovaleryl coenzyme A, 2-methylbutyryl coenzyme A, and isobutyryl coenzyme A, respectively, in the presence of sulfhydryl coenzyme A and benzyl viologen. The acyl coenzyme A's were converted to acyl phosphates by phosphate branched-chain acyltransferase enzymatic activities. Branched-chain fatty acid kinase activities catalyzed formation of isovaleric, 2-methylbutyric, and isobutyric acids from isovaleryl phosphate, 2-methylbutyryl phosphate, and isobutyryl phosphate, respectively. Adenosine 5?-triphosphate was formed during conversion of branched-chain acyl phosphates to branched-chain fatty acids. The results indicate that conversion of l-leucine, l-isoleucine, and l-valine to branched-chain fatty acids by spirochete MA-2 results in adenosine 5?-triphosphate generation. The metabolic pathways utilized for this conversion involve amino acid amino-transferase, 2-keto acid oxidoreductase, phosphate acyltransferase, and fatty acid kinase activities.

Harwood, C. S.; Canale-Parola, E.

1981-01-01

100

Near-infrared spectroscopy (NIRS) with a fibre-optic probe for the prediction of the amino acid composition in animal feeds  

Microsoft Academic Search

The amino acids alanine, aspartic acid, glutamic acid, glycine, phenylalanine, valine, lysine, proline, and tyrosine present in feeds with different textures (blocks, tablets, granules and flour (meal) and used in different stages of animal feeding regimes (lactation, growth, maintenance, etc.) were analysed using near-infrared reflectance spectroscopy (NIRS) technology together with a remote reflectance fibre-optic probe. The method allows immediate control

Inmaculada González-Martín; Noelia Álvarez-García; José Miguel González-Cabrera

2006-01-01

101

Quantitative review of optimum amino acid intakes for young laying pullets  

Microsoft Academic Search

1. Data relating egg output to daily intakes of lysine, methion?ine, tryptophan, isoleucine and valine have been analysed using both published and unpublished sources.2. Amino acid requirements in mg\\/d for individual pullets were estimated by the following equations:where E = egg output in g\\/d and W = body weight in kg.3. Response curves for flocks of pullets were calculated using

M. W. McDonald; T. R. Morris

1985-01-01

102

Far infrared spectra of solid state aliphatic amino acids in different protonation states  

Microsoft Academic Search

Far infrared spectra of zwitterionic, cationic, and anionic forms of aliphatic amino acids in solid state have been studied experimentally. Measurements were done on glycine, L-alanine, L-valine, L-leucine, and L-isoleucine powder samples and film samples obtained from dried solutions prepared at pH ranging from 1 to 13. Solid state density functional theory calculations were also performed, and detailed potential energy

Aurélien Trivella; Thomas Gaillard; Roland H. Stote; Petra Hellwig

2010-01-01

103

Biochemical characterisation of Nicotiana plumbaginifolia auxotrophs that require branched-chain amino acids  

Microsoft Academic Search

The biochemical lesions in six amino acid-requiring auxotrophic lines of Nicotiana plumbaginifolia have been investigated, by means of feeding experiments with [14C] and unlabelled substrates, and enzyme analysis. Three of the lines require isoleucine for growth, are unable to synthesise 2-oxobutyrate in vivo and have no detectable threonine dehydratase (E.C.4.2.1.16) in vitro. The other three lines require (isoleucine + valine),

Roger M. Wallsgrove; Ruth Risiott; Ioan Negrutiu; Simon W. J. Bright

1986-01-01

104

Cheese flavour formation by amino acid catabolism  

Microsoft Academic Search

Amino acid catabolism is a major process for flavour formation in cheese. The ability of lactic acid bacteria (LAB) and other cheese micro-organisms to degrade amino acids to aroma compounds is highly strain dependent. Generally, amino acid catabolism proceeds by 2 different pathways. The first one, mainly observed for methionine, is initiated by elimination reaction and leads to major sulphur

Mireille Yvon; Liesbeth Rijnen

2001-01-01

105

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

SciTech Connect

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

Romanova, V.S.; Tsyryapkin, V.A.; Vol`pin, M.E. [A.N. Nesmeyanov Institute of Organoelement Compounds, Moscow (Russian Federation)] [and others

1994-12-01

106

?pH-Dependent Amino Acid Transport into Plasma Membrane Vesicles Isolated from Sugar Beet (Beta vulgaris L.) Leaves  

PubMed Central

Proton-coupled aliphatic, neutral amino acid transport was investigated in plasma membrane vesicles isolated from sugar beet (Beta vulgaris L., cv Great Western) leaves. Two neutral amino acid symport systems were resolved based on inter-amino acid transport competition and on large variations in the specific activity of each porter in different species. Competitive inhibition was observed for transport competition between alanine, methionine, glutamine, and leucine (the alanine group) and between isoleucine, valine, and threonine (the isoleucine group). The apparent Km and Ki values were similar for transport competition among amino acids within the alanine group. In contrast, the kinetics of transport competition between these two groups of amino acids did not fit a simple competitive model. Furthermore, members of the isoleucine group were weak transport antagonists of the alanine group. These results are consistent with two independent neutral amino acid porters. In support of that conclusion, the ratio of the specific activity of alanine transport versus isoleucine transport varied from two- to 13-fold in plasma membrane vesicles isolated from different plant species. This ratio would be expected to remain relatively stable if these amino acids were moving through a single transport system and, indeed, the ratio of alanine to glutamine transport varied less than twofold. Analysis of the predicted structure of the aliphatic, neutral amino acids in solution shows that isoleucine, valine, and threonine contain a branched methyl or hydroxyl group at the ?-carbon position that places a dense electron cloud close to the ?-amino group. This does not occur for the unbranched amino acids or those that branch further away, e.g. leucine. We hypothesize that this structural feature of isoleucine, valine, and threonine results in unfavorable steric interactions with the alanine transport system that limits their flux through this porter. Hydrophobicity and hydrated volumes did not account for the observed differences in transport specificity.

Li, Zhen-Chang; Bush, Daniel R.

1991-01-01

107

Single-site Biomimetic Amino Acid Complexes for the Benign Oxidation of Hydrocarbons and Alcohols  

Microsoft Academic Search

Zeolite encapsulated amino acid complexes such as Fe-proline, Fe-histidine and Cu-valine have shown significant promise in\\u000a the selective oxidation of hydrocarbons such as cyclohexane and benzylic alcohols. This novel encapsulation procedure, which\\u000a involves building a zeolite (host) around a pre-formed and structurally defined amino acid complex (guest), results in the\\u000a generation of isolated single-sites for catalytic oxidations. IR and UV–Vis

Joanna Dzierzak; Michael Lefenfeld; Robert Raja

2009-01-01

108

Biological role of the general control of amino acid biosynthesis in Saccharomyces cerevisiae.  

PubMed

The biological role of the "general control of amino acid biosynthesis" has been investigated by analyzing growth and enzyme levels in wild-type, bradytrophic, and nonderepressing mutant strains of Saccharomyces cerevisiae. Amino acid limitation was achieved by using either bradytrophic mutations or external amino acid imbalance. In the wild-type strain noncoordinate derepression of enzymes subject to the general control has been found. Derepressing factors were in the order of 2 to 4 in bradytrophic mutant strains grown under limiting conditions and only in the order of 1.5 to 2 under the influence of external amino acid imbalance. Nonderepressing mutations led to slower growth rates under conditions of amino acid limitation, and no derepression of enzymes under the general control was observed. The amino acid pools were found to be very similar in the wild type and in nonderepressing mutant strains under all conditions tested. Our results indicate that the general control affects all branched amino acid biosynthetic pathways, namely, those of the aromatic amino acids and the aspartate family, the pathways for the basic amino acids lysine, histidine, and arginine, and also the pathways of serine and valine biosyntheses. PMID:9279372

Niederberger, P; Miozzari, G; Hütter, R

1981-07-01

109

Biological role of the general control of amino acid biosynthesis in Saccharomyces cerevisiae.  

PubMed Central

The biological role of the "general control of amino acid biosynthesis" has been investigated by analyzing growth and enzyme levels in wild-type, bradytrophic, and nonderepressing mutant strains of Saccharomyces cerevisiae. Amino acid limitation was achieved by using either bradytrophic mutations or external amino acid imbalance. In the wild-type strain noncoordinate derepression of enzymes subject to the general control has been found. Derepressing factors were in the order of 2 to 4 in bradytrophic mutant strains grown under limiting conditions and only in the order of 1.5 to 2 under the influence of external amino acid imbalance. Nonderepressing mutations led to slower growth rates under conditions of amino acid limitation, and no derepression of enzymes under the general control was observed. The amino acid pools were found to be very similar in the wild type and in nonderepressing mutant strains under all conditions tested. Our results indicate that the general control affects all branched amino acid biosynthetic pathways, namely, those of the aromatic amino acids and the aspartate family, the pathways for the basic amino acids lysine, histidine, and arginine, and also the pathways of serine and valine biosyntheses.

Niederberger, P; Miozzari, G; Hutter, R

1981-01-01

110

Amino acids and gut function  

Microsoft Academic Search

The intestine is not only critical for the absorption of nutrients, but also interacts with a complex external milieu. Most\\u000a foreign antigens enter the body through the digestive tract. Dietary amino acids are major fuels for the small intestinal\\u000a mucosa, as well as important substrates for syntheses of intestinal proteins, nitric oxide, polyamines, and other products\\u000a with enormous biological importance.

W. W. Wang; S. Y. Qiao; D. F. Li

2009-01-01

111

Stereoselective ribosylation of amino acids.  

PubMed

The glycosylation properties of ribofuranosyl N-phenyltrifluoroacetimidates toward carboxamide side chains of asparagine and glutamine were investigated. Conditions were found that promote nearly exclusive formation of the ?-anomerically configured N-glycosides. The strategy allows for the synthesis of Fmoc-amino acids suitably modified for the preparation of ADP-ribosylated peptides. Furthermore, ribosylation of serine with these donors proved to be completely ?-selective, and for the first time, ?-ribosylated glutamic and aspartic acid, the naturally occurring sites for poly-ADP-ribosylation, were synthesized. PMID:23614697

Kistemaker, Hans A V; van Noort, Gerbrand J van der Heden; Overkleeft, Herman S; van der Marel, Gijsbert A; Filippov, Dmitri V

2013-04-24

112

Alicyclic ?-amino acids in Medicinal Chemistry  

Microsoft Academic Search

Summary. The structural element of alicyclic ?-amino acids shows some remarkable biological effects: For some 5- and 6-membered ?-amino acids a unique anti fungal activity has been observed, 7-membered ?-amino acid derivatives have been investigated for neurological disorders. The application of 5-, 6- and 7-membered alicyclic ?-amino acids in Medicinal Chemistry will be reported.\\u000a\\u0009\\u0009\\u0009\\u0009\\u0009Caption of figure

A. Kuhl; M. G. Hahn; M. Dumi?; J. Mittendorf

2005-01-01

113

On the role of the functional group in determining the strength of hydrophobic interactions in aqueous solutions of ?-amino acid derivatives  

Microsoft Academic Search

Calorimetric measurements were carried out at 25°C on binary aqueous solutions containing N-acetyl derivatives of the following a-amino acids: glycine, alanine, valine, leucine, norleucine, aspartic acid, glutamic acid, phenylalanine, methionine, asparagine, glutamine, cysteine, histidine, serine. The N-acetyl derivative of the a-amino acid proline was also studied. The results obtained have been used to calculate the pairwise enthalpic interaction coefficients and

Giuseppina Castronuovo; Vittorio Elia; Filomena Velleca

1996-01-01

114

Thermal phase transitions of solid chiral N, N?-carbonyl-bis-( l-amino acids) and their methyl and benzyl esters  

Microsoft Academic Search

Compounds derived from different N,N?-carbonyl-bis-(l-amino acids) and their methyl and benzyl esters were synthesized and characterized by elemental analysis, infrared and nuclear magnetic resonance. The amino acids used were valine, leucine, phenylglycine and phenylalanine. All compounds revealed complex thermal behaviour as proved by differential scanning calorimetry, X-ray powder diffractometry and optical birefringence observation by polarizing microscope. Above isotropization temperature N,N?-carbonyl-bis-(l-amino

Vlasta Tomaši?; Janja Makarevi?; Milan Joki?

2006-01-01

115

Recombinant bovine somatotropin decreases hepatic amino acid catabolism in female rats.  

PubMed

The effect of recombinant bovine somatotropin (rbST) on hepatic amino acid catabolism in female rats was investigated. Daily injections of rbST for 5 d decreased liver homogenate lysine alpha-ketoglutarate reductase (EC 1.5.1.8) activity (P < 0.05) and liver homogenate lysine oxidation (P < 0.05) approximately 35%. Liver homogenate methionine and valine oxidation were depressed approximately 20 (P = 0.13) and 35% (P < 0.05), respectively. These data show a decrease in hepatic capacity to oxidize amino acids in rats administered rbST. Whether depressed liver amino acid degrading enzyme activity plays a role in amino acid oxidation in vivo remains to be evaluated. PMID:8648440

Blemings, K P; Gahl, M J; Crenshaw, T D; Benevenga, N J

1996-06-01

116

21 CFR 172.320 - Amino acids.  

Code of Federal Regulations, 2010 CFR

... 2009-04-01 2009-04-01 false Amino acids. 172.320 Section 172.320 Food and...Dietary and Nutritional Additives § 172.320 Amino acids. The food additive amino acids may be safely used as nutrients added to...

2009-04-01

117

21 CFR 172.320 - Amino acids.  

Code of Federal Regulations, 2010 CFR

...3 2010-01-01 2009-04-01 true Amino acids. 172.320 Section 172.320 Food and...Dietary and Nutritional Additives § 172.320 Amino acids. The food additive amino acids may be safely used as nutrients added to...

2010-01-01

118

E.S.R. of spin-trapped radicals in gamma-irradiated polycrystalline amino acids. Chromatographic separation of radicals.  

PubMed

The free radicals produced by gamma-radiolysis of polycrystalline amino acids (L-valine, L-leucine, L-isoleucine and L-proline) at room temperature in the absence of air were investigated by spin trapping with 2-methyl-2-nitrosopropane (MNP). The spin adducts produced by dissolving the irradiated solids in aqueous MNP solutions were separated by high-performance liquid chromatography and then identified by e.s.r. Deamination (ring-opening reaction for L-proline) was observed for all amino acid. For L-valine and L-leucine, H-abstraction from the tertiary carbon in the side chains occurred. For isoleucine, H-abstractions from the alpha-carbon of the amino acid and from a non-terminal carbon in the side chain were found. PMID:6288602

Makino, K; Riesz, P

1982-06-01

119

The retention and recovery of amino acids from pork longissimus muscle following cooking to either 60°C or 75°C.  

PubMed

Samples of pork longissimus muscle (n=16) cooked to either 60°C or 75°C in a water bath for 90min were assessed for amino acid composition. Recovery of protein in the cooked meat plus the cooking juice was >93% and was slightly higher at 60°C (P=0.031), but retention in the meat was only 89% and 82% for the lower and higher temperatures (P<0.0001). Individual amino acids varied in recovery and retention with retention being particularly low for taurine and histidine. The balance of indispensable amino acids was less than ideal, with leucine and valine being the limiting amino acids by about 30% for both raw and cooked pork. Cooking had no detrimental effect on amino acid balance. Some examples of small effects of genotype and sex on amino acid composition of pork were shown. PMID:23954276

Wilkinson, B H P; Lee, E; Purchas, R W; Morel, P C H

2013-07-19

120

Amino Acid Composition of Germinating Cotton Seeds  

PubMed Central

Total and free amino acid composition of germinating cotton seeds (Gossypium hirsutum L.) was determined. The germinating seeds were separated into cotyledon and developing axis fractions daily and the composition of each tissue was summed to get the whole seed composition. By separating the developing seeds into these two tissue fractions, and determining total and free amino acids, a balance sheet was developed for each amino acid. This technique allowed changes in distribution with time of each amino acid to be followed in each tissue. Data for total content and amount in protein of each amino acid are presented. Asparagine increased in the whole seed, and most of this increase was found in the free pool of the developing axis. Other amino acids (e.g. arginine, glutamic acid) increased in the free pool but showed an over-all decrease, indicating that they were being metabolized. Amino acid contents of storage and nonstorage protein isolates were determined.

Elmore, C. Dennis; King, Earl E.

1978-01-01

121

Characterization of neutral amino acid transport in a marine pseudomonad.  

PubMed Central

The transport of neutral amino acids in marine pseudomonad B-16 (ATCC 19855) has been investigated. From patterns of competitive inhibition, mutant analysis, and kinetic data, two active transport systems with overlapping substrate specificities were distinguished and characterized. One system (DAG) served glycine, D-alanine, D-serine, and alpha-aminoisobutyric acid (AIB) and, to a lesser extent, L-alanine and possibly other related neutral D- and L-amino acids. The other system (LIV) showed high stereospecificity for neutral amino acids with the L configuration and served primarily to transport L-leucine, L-isoleucine, L-valine, and L-alanine. This system exhibited low affinity for alpha-aminoisobutyric acid. Neither system was able to recognize structural analogues with modified alpha-amino or alpha-carboxyl groups. The kinetic parameters for L-alanine transport by the DAG and LIV systems were determined with appropriate mutants defective in either system. For L-alanine, Kt values of 4.6 X 10(-5) and 1.9 X 10(-4) M and Vmax values of 6.9 and 20.8 nmol/min per mg of cell dry weight were obtained for transport via the DAG and LIV systems respectively. alpha-Aminoisobutyric acid transport heterogeneity was also resolved with the mutants, and Kt values of 2.8 X 10(-5) and 1.4 X 10(-3) M AIB were obtained for transport via the DAG and LIV systems, respectively. Both systems required Na+ for activity (0.3 M Na+ optimal) and in this regard are distinguished from systems of similar substrate specificity reported in nonmarine bacteria.

Fein, J E; MacLeod, R A

1975-01-01

122

Summary and implications of reported amino acid concentrations in the Murchison meteorite  

NASA Astrophysics Data System (ADS)

A study of literature reports of the concentrations of amino acids in extracts from the Murchison meteorite shows that many of the concentration ratios are constant. There are two possible interpretations of these ratios. One is that they are controlled by the pathways through which the amino acids formed, from which it follows that the amino acids are distributed in the same proportions throughout the meteorite. The other interpretation is that the ratios result from the analytical procedures used to extract the amino acids from the meteorite. These methods rely heavily on high-temperature (100°C) aqueous extraction and subsequent high-temperature acid hydrolysis. A correlation was observed in the present study between the relative concentrations of several amino acids in the meteorite extracts and their relative aqueous solubilities at 100°C (alanine, valine, leucine, isoleucine, norleucine, aspartic acid, glutamic acid, and glycine). The extract solutions are dilute, and far from the saturation limits, but these correlations suggest that the sampling procedure affects directly the reported concentrations for these amino acids. Ratios of the concentration of serine to those of glycine are also constant but cannot be accounted for solely by relative solubilities, and, as suggested elsewhere, serine as well as phenylalanine and methionine may be terrestrial contaminants. Data for -alanine, -aminobutyric acid, proline, sarcosine, alloisoleucine, -aminoisobutyric acid, -aminobutyric acid, and threonine also show constant abundances relative to glycine, but lack of solubility data at extraction conditions prohibits evaluating the extent of possible sampling bias for these amino acids. If the extraction process does not bias the results, and all extractable amino acids are removed from meteorite samples, then the properties of amino acids which control both their solubilities and their concentrations in the meteorite need to be established. The possibility of sampling bias needs to be tested experimentally before concluding that extraction is complete, and that the constant relative abundances indicate that the relative concentrations of amino acids are homogeneous in the meteorite.

Shock, Everett L.; Schulte, Mitchell D.

1990-11-01

123

Sugar amino acids in designing new molecules.  

PubMed

Emulating the basic principles followed by nature to build its vast repertoire of biomolecules, organic chemists are developing many novel multifunctional building blocks and using them to create 'nature-like' and yet unnatural organic molecules. Sugar amino acids constitute an important class of such polyfunctional scaffolds where the carboxyl, amino and hydroxyl termini provide an excellent opportunity to organic chemists to create structural diversities akin to Nature's molecular arsenal. This article describes some of our works on various sugar amino acids and many other related building blocks, like furan amino acids, pyrrole amino acids etc. used in wide-ranging peptidomimetic studies. PMID:16133829

Chakraborty, Tushar Kanti; Srinivasu, Pothukanuri; Tapadar, Subhasish; Mohan, Bajjuri Krishna

2005-03-01

124

Application of environmental forensics to identify the sources of ground water contamination using amino acid "finger print"  

NASA Astrophysics Data System (ADS)

The analysis of patterns of amino acids of the leachate from livestock burial site and the wastewater from the manure treatment plant was performed to trace the source of NO3-N contamination in groundwater near mass burial sites. Amino acid was analyzed with LC-MSMS using ODS-II column after the derivatiztion with PITC (phenylisothiocyanate) by following Edman Method. The average concentration of amino acid in the burial leachate was 531.90 mg/L and livestock wastewater was 1.75 mg/L. The concentration of burial leachate is about 300 times higher than that of livestock wastewater. The order of the concentration of each amino acid which were commonly detected in leachate was Valin > Leucine > Isoleucin. On the other hands, livestock wastewater showed different trend (Alanine > Lysine > Valine). Six amino acids among 20 amino acids which were stably detected in leachate and livestock wastewater were selected and compared with peak pattern. By determining the relative ratio of concentrations of amino acids (Ile/Val, Leu/Trp, Val/Trp, Lys/Leu, Lys/Ile, Met/Lys) in the same sample, the sources of the contamination was concluded. Based on this analysis using those indicators, samples affected by livestock wastewater were 43.0% (324 samples) and samples influenced by fertilizer or compost were 57.0% (470 samples) among 754 samples. Any sample among 754 samples didn't seem to be effected by leachate of nearby burial site.

Choi, J.; Kim, J.; Park, J.; Nam, Y.; Lee, J.; Yoo, E.; Kim, H.; Lee, W.; Choe, S.; Han, J.

2011-12-01

125

Electrophysiological evidence for acidic, basic, and neutral amino acid olfactory receptor sites in the catfish  

PubMed Central

Electrophysiological experiments indicate that olfactory receptors of the channel catfish, Ictalurus punctatus, contain different receptor sites for the acidic (A), basic (B), and neutral amino acids; further, at least two partially interacting neutral sites exist, one for the hydrophilic neutral amino acids containing short side chains (SCN), and the second for the hydrophobic amino acids containing long side chains (LCN). The extent of cross-adaptation was determined by comparing the electro-olfactogram (EOG) responses to 20 "test" amino acids during continuous bathing of the olfactory mucosa with water only (control) to those during each of the eight "adapting" amino acid regimes. Both the adapting and test amino acids were adjusted in concentrations to provide approximately equal response magnitudes in the unadapted state. Under all eight adapting regimes, the test EOG responses were reduced from those obtained in the unadapted state, but substantial quantitative differences resulted, depending upon the molecular structure of the adapting stimulus. Analyses of the patterns of EOG responses to the test stimuli identified and characterized the respective "transduction processes," a term used to describe membrane events initiated by a particular subset of amino acid stimuli that are intricately linked to the origin of the olfactory receptor potential. Only when the stimulus compounds interact with different transduction processes are the stimuli assumed to bind to different membrane "sites." Four relatively independent L-alpha-amino acid transduction processes (and thus at least four binding sites) identified in this report include: (a) the A process for aspartic and glutamic acids; (b) the B process for arginine and lysine; (c) the SCN process for glycine, alanine, serine, glutamine, and possibly cysteine; (d) the LCN process for methionine, ethionine, valine, norvaline, leucine, norleucine, glutamic acid-gamma-methyl ester, histidine, phenylalanine, and also possibly cysteine. The specificities of these olfactory transduction processes in the catfish are similar to those for the biochemically determined receptor sites for amino acids in other species of fishes and to amino acid transport specificities in tissues of a variety of organisms.

1984-01-01

126

Preparation and characterisation of new oxovanadium(IV) Schiff base complexes derived from amino acids and aromatic o-hydroxyaldehydes  

Microsoft Academic Search

A range of mostly new oxovanadium(IV) complexes is described. They contain coordinated Schiff bases, made from natural amino acids (glycine, alanine, valine, leucine, isoleucine, methionine, phenylalanine, threonine, aspartic acid, and histidine) and salicylaldehyde or such derivatives as 3-, 4-, or 5-methoxy-salicylaldehyde. The coordination sphere is completed by simple ligands like water, 2,2?-bipyridyl or pyridine. The compounds are characterised and the

J. Costa Pessoa; I. Cavaco; I. Correia; M. T. Duarte; R. D. Gillard; R. T. Henriques; F. J. Higes; C. Madeira; I. Tomaz

1999-01-01

127

Time Series Analysis of Fed-batch Fermentation Process for L-valine Production  

Microsoft Academic Search

Fed-batch fermentation processes are some of the most efficient and wildly applied types of cultivation for industrial production of most amino acids including L-valine. Time series analysis is an important tool for description of the experimental data. This article deals with statistical inference from the time series analysis of generalised stoichiometric equations as a hypothesis for modelling and optimisation. The

Tzanko Georgiev; Velitchka Ivanova; Julia Kristeva; Ignat Dimov; Alexander Ratkov

2006-01-01

128

Effect of different postharvest temperatures on the accumulation of sugars, organic acids, and amino acids in the juice sacs of Satsuma mandarin (Citrus unshiu Marc.) fruit.  

PubMed

To elucidate the effect of different postharvest temperatures on the accumulation of sugars, organic acids, and amino acids and to determine the best temperature to minimize their postharvest change, their content after harvest was investigated at 5, 10, 20, and 30 °C for 14 days in the juice sacs of Satsuma mandarin (Citrus unshiu Marc. cv. Aoshima-unshiu) fruit. In all sugars, the changes were negligible at all temperatures. Organic acids decreased slightly at all temperatures, with the exception of malic acid at 30 °C, which increased slightly. Two amino acids, ornithine and glutamine, increased at 5 °C, but they did not increase at other temperatures. In 11 amino acids (phenylalanine, tryptophan, tyrosine, isoleucine, leucine, valine, threonine, lysine, methionine, histidine, and ?-amino butyric acid), the content was higher at 20 and 30 °C than at other temperatures. Thus, the content of amino acids was more variable than that of sugars and organic acids in response to temperatures. Moreover, amino acids responded to temperature differently: two amino acids were cold responsive, and 11 were heat-responsive. The best temperature to minimize the postharvest changes in amino acid profiles in the juice sacs of Aoshima-unshiu was 10 °C. The responsiveness to temperatures in two cold-responsive (ornithine and glutamine) and five heat-responsive (phenylalanine, tryptophan, valine, lysine, and histidine) amino acids was conserved among three different Satsuma mandarin cultivars, Aoshima-unshiu (late-maturing cultivar), Silverhill (midmaturing cultivar), and Miyagawa-wase (early-maturing cultivar). The metabolic responsiveness to temperature stress was discussed on the basis of the changes in the amino acid profile. PMID:22950419

Matsumoto, Hikaru; Ikoma, Yoshinori

2012-09-19

129

Nonprotein Amino Acids from Spark Discharges and Their Comparison with the Murchison Meteorite Amino Acids  

PubMed Central

All the nonprotein amino acids found in the Murchison meteorite are products of the action of electric discharge on a mixture of methane, nitrogen, and water with traces of ammonia. These amino acids include ?-amino-n-butyric acid, ?-aminoisobutyric acid, norvaline, isovaline, pipecolic acid, ?-alanine, ?-amino-n-butyric acid, ?-aminoisobutyric acid, ?-aminobutyric acid, sarcosine, N-ethylglycine, and N-methylalanine. In addition, norleucine, alloisoleucine, N-propylglycine, N-isopropylglycine, N-methyl-?-alanine, N-ethyl-?-alanine ?,?-diaminopropionic acid, isoserine, ?,?-diaminobutyric acid, and ?-hydroxy-?-aminobutyric acid are produced by the electric discharge, but have not been found in the meteorite.

Wolman, Yecheskel; Haverland, William J.; Miller, Stanley L.

1972-01-01

130

Astroglial amino acid-based transmitter receptors.  

PubMed

Amino acids appear in prebiotic period being one of the first organic molecules on Earth. For neurobiologists, it is of importance that AAs are not only representing building blocks of life, but are also the essential part of metabolism and cellular signaling. In the mammalian brain, the most common excitatory and inhibitory transmitters acting upon cellular plasmalemmal receptors are the amino acid glutamate and its derivative ?-aminobutyric acid, respectively. Other amino acids, i.e. aspartate, glycine, D-serine, and homocysteic acid, as well as the sulfonic acid taurine, are also active compounds involved in receptor-mediated brain signaling. Receptors for these amino acid-based transmitters are either ion channels, also referred to as ionotropic receptors, or metabotropic, i.e. seven transmembrane domain G-protein coupled receptors. In this mini-review, we focus our interest on amino acid-based transmitter receptors on neuroglia, astrocytes in particular. PMID:23354277

Parpura, Vladimir; Verkhratsky, Alexei

2013-01-26

131

METABOLISM OF ?-AMINO ACIDS V.  

PubMed Central

Hardman, John K. (National Heart Institute, National Institutes of Health, Bethesda, Md.) and Thressa C. Stadtman. Metabolism of ?-amino acids. V. Energetics of the ?-aminobutyrate fermentation by Clostridium aminobutyricum. J. Bacteriol. 85:1326–1333. 1963.—Clostridium aminobutyricum utilizes ?-aminobutyrate as its sole carbon, nitrogen, and energy source, producing ammonia, acetate, and butyrate as a result of this fermentation. Coenzyme A (CoA)-transferase, phosphotransacetylase, and acetokinase activities have been demonstrated in crude extracts of the organism; the coupling of the reactions catalyzed by these enzymes to the fermentation reactions provides a mechanism whereby C. aminobutyricum can obtain energy, in the form of adenosine triphosphate, from the decomposition of ?-aminobutyrate. Indirect evidence of additional phosphorylation, at the electron-transport level, has been obtained from molar growth yield studies and from the inhibition by 2,4-dinitrophenol of butyrate synthesis from ?-aminobutyrate and from crotonyl-CoA.

Hardman, John K.; Stadtman, Thressa C.

1963-01-01

132

Molecular Ontology of Amino Acid Transport  

Microsoft Academic Search

\\u000a This review focuses on the comparative physiology and phylogeny of plasma membrane transporters that absorb and redistribute\\u000a amino acids in organisms. The first section briefly summarizes the life history of the environmental flux and metabolism of\\u000a amino acids. It reveals a set of geological and biological events that may have shaped amino acid transport mechanisms, which\\u000a evolved under everlasting antagonism

Dmitri Y. Boudko

133

Characteristics of amino acid uptake in barley  

Microsoft Academic Search

Plants have the ability to take up organic nitrogen (N) but this has not been thoroughly studied in agricultural plants. A\\u000a critical question is whether agricultural plants can acquire amino acids in a soil ecosystem. The aim of this study was to\\u000a characterize amino acid uptake capacity in barley (Hordeum vulgare L.) from a mixture of amino acids at concentrations

Sandra Jämtgård; Torgny Näsholm; Kerstin Huss-Danell

2008-01-01

134

Understanding conserved amino acids in proteins  

NASA Astrophysics Data System (ADS)

It has been conjectured that evolution exerted pressure to preserve amino acids bearing thermodynamic, kinetic, and functional roles. In this letter we show that the physical requirement to maintain protein stability gives rise to a sequence conservatism pattern that is in remarkable agreement with that found in natural proteins. Based on the physical properties of amino acids, we propose a model of evolution that explains conserved amino acids across protein families sharing the same fold.

Dokholyan, Nikolay V.; Mirny, Leonid A.; Shakhnovich, Eugene I.

2002-11-01

135

What Amino Acid Properties Affect Protein Evolution?  

Microsoft Academic Search

.   We studied 10 protein-coding mitochondrial genes from 19 mammalian species to evaluate the effects of 10 amino acid properties\\u000a on the evolution of the genetic code, the amino acid composition of proteins, and the pattern of nonsynonymous substitutions.\\u000a The 10 amino acid properties studied are the chemical composition of the side chain, two polarity measures, hydropathy, isoelectric\\u000a point, volume,

Xuhua Xia; Wen-Hsiung Li

1998-01-01

136

Synthesis of optically active amino acids from alpha-keto acids with Escherichia coli cells expressing heterologous genes.  

PubMed Central

We describe a simple method for enzymatic synthesis of L and D amino acids from alpha-keto acids with Escherichia coli cells which express heterologous genes. L-amino acids were produced with thermostable L-amino acid dehydrogenase and formate dehydrogenase (FDH) from alpha-keto acids and ammonium formate with only an intracellular pool of NAD+ for the regeneration of NADH. We constructed plasmids containing, in addition to the FDH gene, the genes for amino acid dehydrogenases, including i.e., leucine dehydrogenase, alanine dehydrogenase, and phenylalanine dehydrogenase. L-Leucine, L-valine, L-norvaline, L-methionine, L-phenylalanine, and L-tyrosine were synthesized with the recombinant E. coli cells with high chemical yields (> 80%) and high optical yields (up to 100% enantiomeric excess). Stereospecific conversion of various alpha-keto acids to D amino acids was also examined with recombinant E. coli cells containing a plasmid coding for the four heterologous genes of the thermostable enzymes D-amino acid aminotransferase, alanine racemase, L-alanine dehydrogenase, and FDH. Optically pure D enantiomers of glutamate and leucine were obtained.

Galkin, A; Kulakova, L; Yoshimura, T; Soda, K; Esaki, N

1997-01-01

137

The Amino Acid Valine Is Secreted in Continuous-Flow Bacterial Biofilms  

Microsoft Academic Search

Biofilms are structured communities characterized by distinctive gene expression patterns and profound physiological changes compared to those of planktonic cultures. Here, we show that many gram-negative bacterial biofilms secrete high levels of a small-molecular-weight compound, which inhibits the growth of only Escherichia coli K-12 and a rare few other natural isolates. We demonstrate both genetically and biochemically that this molecule

Jaione Valle; Sandra Da Re; Solveig Schmid; David Skurnik; Richard D'Ari; Jean-Marc Ghigo

2008-01-01

138

Amino acid composition of some Mexican foods.  

PubMed

Knowledge of the amino acid composition of foods is essential to calculate their chemical score, which is used to predict protein quality of foods and diets. Though amino acid composition of many foods is reasonably well established, better knowledge is needed on native foods consumed in different regions and countries. This paper presents the amino acid composition of different presentations of raw and processed foods produced and consumed in Mexico. The amino acid composition was determined using Beckman amino acid analyzers (models 116 and 6300). Tryptophan was determined using the Spies and Chambers method. Of the different foods analyzed, some comments are made on native or basic foods in Mexico: Spirulin, where lysine is the limiting amino acid, with a chemical score of 67%, is a good source of tryptophan (1.16g/16 gN); amaranth contains high levels of sulphur amino acids (4.09 to 5.34 g/16gN), with a protein content of 15 g/100g; and pulque, a Pre-Hispanic beverage that contains high levels of tryptophan (2.58 g/16 gN) and sulphur amino acids (2.72 g/16 gN). Finally, insects are good sources of sulphur amino acids and lysine. PMID:16335228

Morales de León, Josefina; Camacho, M Elena; Bourges, Héctor

2005-06-01

139

Ion-induced fragmentation of amino acids: effect of the environment.  

PubMed

In general, radiation-induced fragmentation of small amino acids is governed by the cleavage of the C-C(?) bond. We present results obtained with 300 keV Xe(20+) ions that allow molecules (glycine and valine) to be ionised at large distances without appreciable energy transfer. Also in the present case, the C-C(?) bond turns out to be the weakest link and hence its scission is the dominant fragmentation channel. Intact ionised molecules are observed with very low intensities. When the molecules are embedded in a cluster of amino acids, a protective effect of the environment is observed. The fragmentation pattern changes: the C-C(?) bond becomes more protected and stable amino acid cations are observed as fragments of the molecular clusters. Evidently, the molecular cluster acts as a "buffer" for the excess energy, capable of rapidly redistributing excess energy and charge. PMID:21370376

Maclot, Sylvain; Capron, Michael; Maisonny, Rémi; ?awicki, Arkadiusz; Méry, Alain; Rangama, Jimmy; Chesnel, Jean-Yves; Bari, Sadia; Hoekstra, Ronnie; Schlathölter, Thomas; Manil, Bruno; Adoui, Lamri; Rousseau, Patrick; Huber, Bernd A

2011-03-02

140

Branched chain amino acid-enriched solutions in the septic patient. A randomized, prospective trial.  

PubMed Central

A prospective, randomized trial was undertaken to compare the nutritional efficacy in surgical stress of a standard amino acid solution and two branched chain-enriched amino acid solutions: one enriched primarily with valine, the other with leucine. The study comprised 37 patients in the surgical intensive care unit who received isocaloric, isonitrogenous parenteral nutrition started within 24 hours of the onset of major operation, injury, or sepsis. Nitrogen retention was marginally but statistically significantly better on days 5, 7, and 10 in both groups of patients receiving the branched chain-enriched solutions, but differences in cumulative nitrogen balance were not statistically significant. Amino acid composition appeared to be important in that the group receiving the leucine-enriched solution appeared to maintain hepatic protein synthesis better (as manifest by higher short-turnover plasma protein concentrations) and required less exogenous insulin to maintain euglycemia. Improved outcome was not seen in the groups receiving the branched chain-enriched solutions.

Bower, R H; Muggia-Sullam, M; Vallgren, S; Hurst, J M; Kern, K A; LaFrance, R; Fischer, J E

1986-01-01

141

Synthesis of the amino acid conjugates of epi-jasmonic acid.  

PubMed

The TES ether of the C6-hydroxy derivative of naturally occurring epi-jasmonic acid (epi-JA) was designed as epimerization-free equivalent of epi-JA. The TES ether was synthesized from (1R,4S)-4-hydroxycyclopent-2-enyl acetate in 13 steps. The acid part of the ether was activated with ClCO2Bui and subjected to condensation with L-amino acid at room temperature for 48 h. The TES group in the condensation product was removed in HCO2H (0°C, 30 min) and the resulting hydroxyl group was oxidized with Jones reagent (acetone, 0°C, 30 min) to furnish the amino acid conjugate of epi-JA. The amino acids examined are L-isoleucine, L-leucine, L-alanine, L-valine, and D-allo-isoleucine, which afforded the conjugates in 48-68% yields with 89-96% diastereomeric purity over the trans isomers. Similarly, the possible three stereoisomers of epi-JA were condensed with L-isoleucine successfully, producing the corresponding stereoisomers in good yields. PMID:21562820

Ogawa, N; Kobayashi, Y

2011-05-12

142

Effective atomic numbers for photon energy absorption of essential amino acids in the energy range 1 keV to 20 MeV  

Microsoft Academic Search

Effective atomic numbers for photon energy-absorption (ZPEAeff) of essential amino acids histidine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine have been calculated by a direct method in the energy region of 1keV to 20MeV. The ZPEAeff values have been found to change with energy and composition of the amino acids. The variations of mass energy-absorption coefficient, effective atomic number

S. R. Manohara; S. M. Hanagodimath

2007-01-01

143

Efficient synthesis of D-branched-chain amino acids and their labeled compounds with stable isotopes using D-amino acid dehydrogenase.  

PubMed

D-Branched-chain amino acids (D-BCAAs) such as D-leucine, D-isoleucine, and D-valine are known to be peptide antibiotic intermediates and to exhibit a variety of bioactivities. Consequently, much effort is going into achieving simple stereospecific synthesis of D-BCAAs, especially analogs labeled with stable isotopes. Up to now, however, no effective method has been reported. Here, we report the establishment of an efficient system for enantioselective synthesis of D-BCAAs and production of D-BCAAs labeled with stable isotopes. This system is based on two thermostable enzymes: D-amino acid dehydrogenase, catalyzing NADPH-dependent enantioselective amination of 2-oxo acids to produce the corresponding D-amino acids, and glucose dehydrogenase, catalyzing NADPH regeneration from NADP(+) and D-glucose. After incubation with the enzymes for 2 h at 65°C and pH 10.5, 2-oxo-4-methylvaleric acid was converted to D-leucine with an excellent yield (>99 %) and optical purity (>99 %). Using this system, we produced five different D-BCAAs labeled with stable isotopes: D-[1-(13)C,(15)N]leucine, D-[1-(13)C]leucine, D-[(15)N]leucine, D-[(15)N]isoleucine, and D-[(15)N]valine. The structure of each labeled D-amino acid was confirmed using time-of-flight mass spectrometry and nuclear magnetic resonance analysis. These analyses confirmed that the developed system was highly useful for production of D-BCAAs labeled with stable isotopes, making this the first reported enzymatic production of D-BCAAs labeled with stable isotopes. Our findings facilitate tracer studies investigating D-BCAAs and their derivatives. PMID:23661083

Akita, Hironaga; Suzuki, Hirokazu; Doi, Katsumi; Ohshima, Toshihisa

2013-05-10

144

Adsorption of amino acids on hydrophilic surfaces  

NASA Astrophysics Data System (ADS)

Sum frequency generation vibrational spectroscopy (SFG) is a powerful tool for in situ investigation of adsorption processes at biologically important solid-liquid interfaces. In this work adsorption of selected amino acids on fused silica, calcium fluoride and titanium dioxide substrates was studied by this technique. SFG spectra taken at the amino acid solution-fused SiO2 interface revealed the lack of formation of any ordered adsorbate layer, regardless of whether acidic or other, e.g. aromatic, amino acids were used. Ex situ spectra (measured after drying the substrate) showed the formation and gradual growth of amino acid crystallites. In the case of CaF2, growth of randomly oriented aspartic acid crystallites was observed even at the solution-substrate interface. Finally, on the TiO2 substrate, acidic amino acids formed a stable, uniform, more or less ordered coating, which remained unchanged even after drying the sample. On the other hand, non-acidic amino acids like phenylalanine showed very little affinity towards TiO2, emphasizing the role of the acidic side chain in the bonding to the substrate. The fact that formation of an amino acid overlayer was observed only on titanium dioxide is probably related to its biocompatibility property.

Pászti, Z.; Keszthelyi, T.; Hakkel, O.; Guczi, L.

2008-06-01

145

Identification of a specific one amino acid change in recombinant human transglutaminase 2 that regulates its activity and calcium sensitivity.  

PubMed

TG2 (transglutaminase 2) is a calcium-dependent protein cross-linking enzyme which is involved in a variety of cellular processes. The threshold level of calcium needed for endogenous and recombinant TG2 activity has been controversial, the former being more sensitive to calcium than the latter. In the present study we address this question by identifying a single amino acid change from conserved valine to glycine at position 224 in recombinant TG2 compared with the endogenous sequence present in the available genomic databases. Substituting a valine residue for Gly224 in the recombinant TG2 increased its calcium-binding affinity and transamidation activity 10-fold and isopeptidase activity severalfold, explaining the inactivity of widely used recombinant TG2 at physiological calcium concentrations. ITC (isothermal titration calorimetry) measurements showed 7-fold higher calcium-binding affinities for TG2 valine residues which could be activated inside cells. The two forms had comparable substrate- and GTP-binding affinities and also bound fibronectin similarly, but coeliac antibodies had a higher affinity for TG2 valine residues. Structural analysis indicated a higher stability for TG2 valine residues and a decrease in flexibility of the calcium-binding loop resulting in improved metal-binding affinity. The results of the present study suggest that Val224 increases TG2 activity by modulating its calcium-binding affinity enabling transamidation reactions inside cells. PMID:23941696

Kanchan, Kajal; Ergülen, Elvan; Király, Robert; Simon-Vecsei, Zsófia; Fuxreiter, Mónika; Fésüs, László

2013-11-01

146

Nickel deficiency disrupts metabolism of ureides, amino acids, and organic acids of young pecan foliage.  

PubMed

The existence of nickel (Ni) deficiency is becoming increasingly apparent in crops, especially for ureide-transporting woody perennials, but its physiological role is poorly understood. We evaluated the concentrations of ureides, amino acids, and organic acids in photosynthetic foliar tissue from Ni-sufficient (Ni-S) versus Ni-deficient (Ni-D) pecan (Carya illinoinensis [Wangenh.] K. Koch). Foliage of Ni-D pecan seedlings exhibited metabolic disruption of nitrogen metabolism via ureide catabolism, amino acid metabolism, and ornithine cycle intermediates. Disruption of ureide catabolism in Ni-D foliage resulted in accumulation of xanthine, allantoic acid, ureidoglycolate, and citrulline, but total ureides, urea concentration, and urease activity were reduced. Disruption of amino acid metabolism in Ni-D foliage resulted in accumulation of glycine, valine, isoleucine, tyrosine, tryptophan, arginine, and total free amino acids, and lower concentrations of histidine and glutamic acid. Ni deficiency also disrupted the citric acid cycle, the second stage of respiration, where Ni-D foliage contained very low levels of citrate compared to Ni-S foliage. Disruption of carbon metabolism was also via accumulation of lactic and oxalic acids. The results indicate that mouse-ear, a key morphological symptom, is likely linked to the toxic accumulation of oxalic and lactic acids in the rapidly growing tips and margins of leaflets. Our results support the role of Ni as an essential plant nutrient element. The magnitude of metabolic disruption exhibited in Ni-D pecan is evidence of the existence of unidentified physiological roles for Ni in pecan. PMID:16415214

Bai, Cheng; Reilly, Charles C; Wood, Bruce W

2006-01-13

147

Normal Raman and surface enhanced Raman spectroscopic experiments with thin layer chromatography spots of essential amino acids using different laser excitation sources  

Microsoft Academic Search

A comparative study of the feasibility and efficiency of Raman spectroscopic detection of thin layer chromatography (TLC) spots of some weak Raman scatterers (essential amino acids, namely, glycine and l-forms of alanine, serine, valine, proline, hydroxyproline, and phenylalanine) was carried out using four different visible and near-infrared (NIR) laser radiations with wavelengths of 532, 633, 785, and 1064 nm. Three

Krisztina István; Gábor Keresztury; Andrea Szép

2003-01-01

148

Amino Acid Uptake in Arbuscular Mycorrhizal Plants  

PubMed Central

We examined the extent to which arbuscular mycorrhizal (AM) fungi root improved the acquisition of simple organic nitrogen (ON) compounds by their host plants. In a greenhouse-based study, we used quantum dots (fluorescent nanoparticles) to assess uptake of each of the 20 proteinaceous amino acids by AM-colonized versus uncolonized plants. We found that AM colonization increased uptake of phenylalanine, lysine, asparagine, arginine, histidine, methionine, tryptophan, and cysteine; and reduced uptake of aspartic acid. Arbuscular mycorrhizal colonization had the greatest effect on uptake of amino acids that are relatively rare in proteins. In addition, AM fungi facilitated uptake of neutral and positively-charged amino acids more than negatively-charged amino acids. Overall, the AM fungi used in this study appeared to improve access by plants to a number of amino acids, but not necessarily those that are common or negatively-charged.

Whiteside, Matthew D.; Garcia, Maria O.; Treseder, Kathleen K.

2012-01-01

149

Biosynthesis of Food Constituents: Amino Acids: 4. Non-protein Amino Acids - a Review  

Microsoft Academic Search

VEL ÍŠEK J., KUBEC R., CEJPEK K. (2006): Biosynthesis of food constituents: Amino acids: 4. Non-protein amino acids - a review. Czech J. Food Sci., 24: 93-109. This review article gives a brief survey of the principal pathways that lead to the biosynthesis of the most important non-protein amino acids occurring in foods and feeds. These amino acids have been

JAN VEL; ROMAN KUBEC; KAREL CEJPEK

2006-01-01

150

Evidence of selection for low cognate amino acid bias in amino acid biosynthetic enzymes  

Microsoft Academic Search

Summary If the enzymes responsible for biosynthesis of a given amino acid are repressed and the cognate amino acid pool suddenly depleted, then derepression of these enzymes and replenishment of the pool would be problematic, if the enzymes were largely composed of the cognate amino acid. In the proverbial 'Catch 22', cells would lack the necessary enzymes to make the

Rui Alves; Michael A. Savageau

2005-01-01

151

Free radical-mediated oxidation of free amino acids and amino acid residues in proteins  

Microsoft Academic Search

Summary. We summarize here results of studies designed to elucidate basic mechanisms of reactive oxygen (ROS)-mediated oxidation of proteins and free amino acids. These studies have shown that oxidation of proteins can lead to hydroxylation of aromatic groups and aliphatic amino acid side chains, nitration of aromatic amino acid residues, nitrosylation of sulfhydryl groups, sulfoxidation of methionine residues, chlorination of

E. R. Stadtman; R. L. Levine

2003-01-01

152

Nutritional value of D-amino acids, D-peptides, and amino acid derivatives in mice  

Technology Transfer Automated Retrieval System (TEKTRAN)

This paper describes a method for determining the nutritional value of D-amino acids, D-peptides, and amino acid derivatives using a growth assay in mice fed a synthetic all-amino acid diet. A large number of experiments were carried out in which a molar equivalent of the test compound replaced a n...

153

Enantiomerically Pure ?-Amino Aldehydes from Silylated ?-Amino Acids  

PubMed Central

The disilylation of ?-amino acids 1 to provide 2 (72–87%) was achieved without racemization. An unprecedented borane-mediated semi-reduction strategy was devised to convert 2 to stable, isolable oxazaborolidines 3 (100%) which were hydrolyzed to provide 5 (49–60%) as pure, stable compounds. Analysis of the Mosher amides (8) of the ?-amino esters 7 reveals that ?2% racemization occurs in the 1?8 conversions.

Soto-Cairoli, Buddy; de Pomar, Jorge Justo; Soderquist, John A.

2008-01-01

154

A New Naturally Occurring AminoAcid  

Microsoft Academic Search

INVESTIGATION of the amino-acids of C. diphtheriæ by paper chromatography has shown that an acid hydrolysate of the water-insoluble portion of the micro-organism contains an unknown ninhydrin-reacting substance in addition to seventeen known amino-acids1. This substance, the position of which on the phenol-collidine chromatogram is shown in Fig. 1, has now been isolated and identified as alpha-?-diaminopimelic acid,

Elizabeth Work

1950-01-01

155

The amino acid requirements of disease  

Microsoft Academic Search

It is now clear that accidental injury, surgery, infection, cancer and psychosocial stress activate new metabolic pathways that consume amino acids. For example, immune activation appears to alter glutamine and arginine metabolism, acute phase protein synthesis demands the increased provision of the aromatic and sulfur amino acids, while an increased rate of glutathione turnover increases the cysteine requirement of the

P. J. Reeds; F. Jahoor

2001-01-01

156

Plasma amino acids in anorexia nervosa  

Microsoft Academic Search

Objective: To evaluate the amino acid profile in a group of adolescents with anorexia nervosa, and to apply alternative ways of presenting and assessing results, so as to increase the information available for understanding the metabolic abnormalities developed in these patients.Design: Plasma amino acid concentrations of a random group of patients with anorexia nervosa compared with values obtained from a

D Moyano; MA Vilaseca; R Artuch; N Lambruschini

1998-01-01

157

Intramolecular arylation of amino acid enolates.  

PubMed

Dianionic enolates formed from N'-aryl urea derivatives of amino acids undergo intramolecular C-arylation by attack of the enolate anion on the N'-aryl ring, leading to a hydantoin derivative of a quaternary amino acid. In situ IR studies allow identification of four intermediates on the reaction pathway. PMID:24022183

Atkinson, Rachel C; Leonard, Daniel J; Maury, Julien; Castagnolo, Daniele; Volz, Nicole; Clayden, Jonathan

2013-09-26

158

Reexamination of Amino Acids in Lunar Soil.  

National Technical Information Service (NTIS)

Amino acids in lunar soils provide an important indicator of the level of prebiotic organic compounds on the moon. The results provide insight into the chemistry of amino acid precursors, and furthermore, given the flux of carbonaceous material to the moo...

K. L. F. Brinton J. L. Bada J. R. Arnold

1993-01-01

159

Amino acid signatures in carbonaceous meteorites  

NASA Astrophysics Data System (ADS)

Carbonaceous chondrites, a class of stony meteorites that contains up to 3 weight-% of organic carbon, are subdivided into types by chemical and mineralogical characteristics. These meteorites are thought to originate from asteroidal parent bodies on which secondary processing in the early history of the solar system has altered interstellar organic precursors into more complex compounds such as amino acids and nucleobases. We have analyzed nine different carbonaceous chondrites and have compared the total and relative amino acid concentrations of hydrolyzed hot-water extracts of these meteorites. When the relative amino acid concentrations [(Beta) -alanine]/[glycine], [AIB]/[glycine] and [D- alanine]/[glycine] of meteorites are plotted against each other, a clustering of the data points of the CM and CI type carbonaceous chondrites can be observed. This signature indicates that the amino acids in the Cms were synthesized via the Strecker synthetic pathway, whereas the amino acids found in the Cis probably have a different synthetic origin.

Botta, Oliver; Glavin, Daniel P.; Bada, Jeffrey L.

2002-02-01

160

Amino Acids in the Martian Meteorite Nakhla  

NASA Astrophysics Data System (ADS)

A suite of protein and nonprotein amino acids were detected with high-performance liquid chromatography in the water- and acid-soluble components of an interior fragment of the Martian meteorite Nakhla, which fell in Egypt in 1911. Aspartic and glutamic acids, glycine, alanine, ? -alanine, and ? -amino-n-butyric acid (? -ABA) were the most abundant amino acids detected and were found primarily in the 6 M HCl-hydrolyzed, hot water extract. The concentrations ranged from 20 to 330 parts per billion of bulk meteorite. The amino acid distribution in Nakhla, including the D/L ratios (values range from <0.1 to 0.5), is similar to what is found in bacterially degraded organic matter. The amino acids in Nakhla appear to be derived from terrestrial organic matter that infiltrated the meteorite soon after its fall to Earth, although it is possible that some of the amino acids are endogenous to the meteorite. The rapid amino acid contamination of Martian meteorites after direct exposure to the terrestrial environment has important implications for Mars sample-return missions and the curation of the samples from the time of their delivery to Earth.

Glavin, Daniel P.; Bada, Jeffrey L.; Brinton, Karen L. F.; McDonald, Gene D.

1999-08-01

161

Comparative analysis of amino acids and amino-acid derivatives in protein crystallization  

PubMed Central

Optimal conditions for protein crystallization are difficult to determine because proteins tend to aggregate in saturated solutions. This study comprehensively evaluates amino acids and amino-acid derivatives as additives for crystallization. This fourth component of the solution increases the probability of crystallization of hen egg-white lysozyme in various precipitants owing to a decrease in aggregation. These results suggest that the addition of certain types of amino acids and amino-acid derivatives, such as Arg, Lys and esterified and amidated amino acids, is a simple method of improving the success rate of protein crystallization.

Ito, Len; Shiraki, Kentaro; Yamaguchi, Hiroshi

2010-01-01

162

Serum branched-chain amino acids in the diagnosis of hyperinsulinism in infancy.  

PubMed

Fasting values of branched-chain amino acids (valine, leucine, and isoleucine) were measured by column chromatography in the sera of 27 normal infants and children, 15 days to 9 years of age, 14 children with documented ketotic hypoglycemia one to 7 years of age, and in 14 sera from six infants, 15 days to 2 years of age, with documented hyperinsulinism. In normal children and those with ketotic hypoglycemia, each individual branched-chain amino acid and their sum were significantly negatively correlated with blood sugar values ranging between 11 and 92 mg/dl (P < 0.001). In infants with hyperinsulinism, branched-chain amino acid concentrations were significantly lower (P < 0.001) without correlation with blood sugar values ranging between 13 and 51 mg/dl, and plasma insulin concentrations (9 to 85 microU/ML). In all the children the sum of branched-chain amino acids was positively correlated with blood beta OH butyrate concentrations measured at the same time (r = 0.75, P < 0.001). The association of low blood sugar and low branched-chain amino acid concentrations during fasting seems characteristic of hyperinsulinism, and the measurement of branched-chain amino acids in these infants offers a physiologic indicator of the diagnosis of hyperinsulinism. PMID:7003083

Chaussain, J L; Georges, P; Gendrel, D; Donnadieu, M; Job, J C

1980-12-01

163

Enantiopure ? 3 -amino acids-2,2-d 2 via homologation of proteinogenic ?-amino acids  

Microsoft Academic Search

Summary.  A procedure for the synthesis of enantiopure ?3-amino acids from proteinogenic ?-amino acids, developed by our group a few years ago, has been modified to enable the production\\u000a of C-2 fully deuterated, C-protected ?3-amino acids and, even more important, the synthesis of valuable deuterium labelled N(Boc)-protected chiral synthons, such as 2-aminoalcohols, 2-aminoiodides, and ?3-amino nitriles.

R. Caputo; L. Longobardo

2007-01-01

164

Amino acid analogs for tumor imaging  

DOEpatents

The invention provides novel amino acid compounds of use in detecting and evaluating brain and body tumors. These compounds combine the advantageous properties of 1-amino-cycloalkyl-1-carboxylic acids, namely, their rapid uptake and prolonged retention in tumors with the properties of halogen substituents, including certain useful halogen isotopes including fluorine-18, iodine-123, iodine-125, iodine-131, bromine-75, bromine-76, bromine-77 and bromine-82. In one aspect, the invention features amino acid compounds that have a high specificity for target sites when administered to a subject in vivo. Preferred amino acid compounds show a target to non-target ratio of at least 5:1, are stable in vivo and substantially localized to target within 1 hour after administration. An especially preferred amino acid compound is [{sup 18}F]-1-amino-3-fluorocyclobutane-1-carboxylic acid (FACBC). In another aspect, the invention features pharmaceutical compositions comprised of an {alpha}-amino acid moiety attached to either a four, five, or a six member carbon-chain ring. In addition, the invention features analogs of {alpha}-aminoisobutyric acid.

Goodman, M.M.; Shoup, T.

1998-09-15

165

Amino acid analogs for tumor imaging  

DOEpatents

The invention provides novel amino acid compounds of use in detecting and evaluating brain and body tumors. These compounds combine the advantageous properties of 1-amino-cycloalkyl-1-carboxylic acids, namely, their rapid uptake and prolonged retention in tumors with the properties of halogen substituents, including certain useful halogen isotopes including fluorine-18, iodine-123, iodine-125, iodine-131, bromine-75, bromine-76, bromine-77 and bromine-82. In one aspect, the invention features amino acid compounds that have a high specificity for target sites when administered to a subject in vivo. Preferred amino acid compounds show a target to non-target ratio of at least 5:1, are stable in vivo and substantially localized to target within 1 hour after administration. An especially preferred amino acid compound is ›.sup.18 F!-1-amino-3-fluorocyclobutane-1-carboxylic acid (FACBC). In another aspect, the invention features pharmaceutical compositions comprised of an .alpha.-amino acid moiety attached to either a four, five, or a six member carbon-chain ring. In addition, the invention features analogs of .alpha.-aminoisobutyric acid.

Goodman, Mark M. (Atlanta, GA); Shoup, Timothy (Decatur, GA)

1998-09-15

166

Amino acid analogs for tumor imaging  

DOEpatents

The invention provides novel amino acid compounds of use in detecting and evaluating brain and body tumors. These compounds combine the advantageous properties of 1-amino-cycloalkyl-1-carboxylic acids, namely, their rapid uptake and prolonged retention in tumors with the properties of halogen substituents, including certain useful halogen isotopes including fluorine-18, iodine-123, iodine-125, iodine-131, bromine-75, bromine-76, bromine-77 and bromine-82. In one aspect, the invention features amino acid compounds that have a high specificity for target sites when administered to a subject in vivo. Preferred amino acid compounds show a target to non-target ratio of at least 5:1, are stable in vivo and substantially localized to target within 1 hour after administration. An especially preferred amino acid compound is ›.sup.18 F!-1-amino-3-fluorocyclobutane-1-carboxylic acid (FACBC). In another aspect, the invention features pharmaceutical compositions comprised of an .alpha.-amino acid moiety attached to either a four, five, or a six member carbon-chain ring. In addition, the invention features analogs of .alpha.-aminoisobutyric acid.

Goodman, Mark M. (Atlanta, GA); Shoup, Timothy (Decatur, GA)

1998-10-06

167

Amino acid analogs for tumor imaging  

DOEpatents

The invention provides novel amino acid compounds of use in detecting and evaluating brain and body tumors. These compounds combine the advantageous properties of 1-amino-cycloalkyl-1-carboxylic acids, namely, their rapid uptake and prolonged retention in tumors with the properties of halogen substituents, including certain useful halogen isotopes including fluorine-18, iodine-123, iodine-125, iodine-131, bromine-75, bromine-76, bromine-77 and bromine-82. In one aspect, the invention features amino acid compounds that have a high specificity for target sites when administered to a subject in vivo. Preferred amino acid compounds show a target to non-target ratio of at least 5:1, are stable in vivo and substantially localized to target within 1 hour after administration. An especially preferred amino acid compound is [{sup 18}F]-1-amino-3-fluorocyclobutane-1-carboxylic acid (FACBC). In another aspect, the invention features pharmaceutical compositions comprised of an {alpha}-amino acid moiety attached to either a four, five, or a six member carbon-chain ring. In addition, the invention features analogs of {alpha}-aminoisobutyric acid.

Goodman, M.M.; Shoup, T.

1998-10-06

168

Serotonin and amino acids: partners in delirium pathophysiology?  

PubMed

Delirium may be the result of dysfunction of multiple interacting neurotransmitter systems. Changes in the levels of various amino acids being precursors of cerebral neurotransmitters may affect their function and, thus, contribute to the development of delirium. Serotonin is one of the neurotransmitters that may play an important role in medical and surgical delirium. Normal serotonin synthesis and release in the human brain is, among others, dependent on the availability of its precursor tryptophan (Trp) from blood. The essential amino acid Trp competes with the other large neutral amino acids (LNAA) tyrosine, phenylalanine, valine, leucine, and isoleucine for transport across the blood-brain barrier. This competition determines its uptake into the brain, represented by the ratio of the plasma level of Trp to the sum of the other LNAA. The plasma ratio of Trp/LNAA, plasma level of Trp, and serotonin in plasma and platelets have been used as indirect peripheral measures for central serotonergic functioning. Both increased and decreased serotonergic activity have been associated with delirium. Serotonin agonists can induce psychosis, both elevated Trp availability and increased cerebral serotonin have been associated with hepatic encephalopathy, and excess serotonergic brain activity has been related to the development of the serotonin syndrome of which delirium is a main symptom. On the other hand, alcohol withdrawal delirium, delirium in levodopa-treated Parkinson patients, and postoperative delirium have been related to reduce cerebral Trp availability from plasma suggesting diminished serotonergic function. Rick factors for delirium such as severe illness, surgery, and trauma can induce immune activation and a physical stress response comprising increased activity of the limbic-hypothalamic-pituitary-adrenocortical axis, the occurrence of a low T3 syndrome, and, possibly, changes in the permeability of the blood-brain barrier. There are indications that these changes have their effect on plasma amino acid concentrations, e.g., Trp, and multiple cerebral neurotransmitters, including serotonin. This stress response may be different depending on the stage of illness being acute or chronic. It will require further study to determine the complex influence of the stress response and immune activation on plasma amino acids, neurotransmitter function and the development of delirium, especially in the more vulnerable older patients. PMID:10837101

van der Mast, R C; Fekkes, D

2000-04-01

169

Amino acid transporters: roles in amino acid sensing and signalling in animal cells.  

PubMed Central

Amino acid availability regulates cellular physiology by modulating gene expression and signal transduction pathways. However, although the signalling intermediates between nutrient availability and altered gene expression have become increasingly well documented, how eukaryotic cells sense the presence of either a nutritionally rich or deprived medium is still uncertain. From recent studies it appears that the intracellular amino acid pool size is particularly important in regulating translational effectors, thus, regulated transport of amino acids across the plasma membrane represents a means by which the cellular response to amino acids could be controlled. Furthermore, evidence from studies with transportable amino acid analogues has demonstrated that flux through amino acid transporters may act as an initiator of nutritional signalling. This evidence, coupled with the substrate selectivity and sensitivity to nutrient availability classically associated with amino acid transporters, plus the recent discovery of transporter-associated signalling proteins, demonstrates a potential role for nutrient transporters as initiators of cellular nutrient signalling. Here, we review the evidence supporting the idea that distinct amino acid "receptors" function to detect and transmit certain nutrient stimuli in higher eukaryotes. In particular, we focus on the role that amino acid transporters may play in the sensing of amino acid levels, both directly as initiators of nutrient signalling and indirectly as regulators of external amino acid access to intracellular receptor/signalling mechanisms.

Hyde, Russell; Taylor, Peter M; Hundal, Harinder S

2003-01-01

170

Quantitative requirement of the hatchling green sea turtle, Chelonia mydas, for valine, leucine, isoleucine and phenylalanine.  

PubMed

Hatchling green sea turtles were fed purified diets containing 36% crude protein (N X 6.25) to determine the quantitative requirements for valine, leucine, isoleucine and phenylalanine. Expressed as percentage of total dry diet, the hatchling green sea turtle requires 1.3% valine, 1.6% leucine, 1.0% isoleucine and 1.0% phenylalanine (in the presence of 0.5% tyrosine). Within the range of isoleucine-leucine levels investigated, there was no apparent interrelationship between the quantitative requirements of these two amino acids. Growth rate was decreased at a high level of phenylalanine, 3.0% of the dry diet. PMID:886391

Wood, F E; Wood, J R

1977-08-01

171

THE IMMUNOGENICITY OF DINITROPHENYL AMINO ACIDS  

PubMed Central

Numerous dinitrophenyl amino acid preparations injected intradermally induced contact hypersensitivity to dinitrochlorobenzene, delayed type skin reactions to DNP-amino acids, and anti-DNP antibodies in guinea pigs. Some DNP-amino adds induced precipitating anti-DNP antibodies in rabbits as well. Some of the DNP-ammo acids studied were regularly immunogenic, possible immunogenic impurities having been excluded by extensive purification procedures. Others were either constantly nonimmunogenic or irregularly immunogenic, e.g., their immunogenicity varying from one preparation lot to another. By means of extensive chemical analyses and the establishment of dose-response curves, we were able to demonstrate in most cases that the immunogenicity was not due to contamination with unreacted dinitrofluorobenzene or other DNP derivatives, to photodecomposition or other degradation products, or to DNP-protein contaminants. Nevertheless, the irregular immunogenicity of several DNP-amino acid preparations can only be explained by a highly immunogenic impurity (or impurities) which we were unable to detect analytically. The regular immunogenicity of some other DNP-amino acids (e.g. di-DNP-L-histidine) appears to be based on a "transconjugation" phenomenon, the DNP group being able to split off from its amino acid carrier and to conjugate secondarily with proteins in vivo and in vitro. Accordingly, the interpretation of some recent data concerning the immunogenicity of low molecular weight hapten-amino acids may have to be reevaluated.

Frey, J. R.; de Weck, A. L.; Geleick, H.; Lergier, W.

1969-01-01

172

Utilization of amino acids by bacteria from the pig small intestine  

Microsoft Academic Search

This study determined the utilization of amino acids (AA) by bacteria from the lumen of the pig small intestine. Digesta samples\\u000a from different segments of the small intestine were inoculated into media containing 10 mmol\\/L each of select AA (l-lysine, l-threonine, l-arginine, l-glutamate, l-histidine, l-leucine, l-isoleucine, l-valine, l-proline, l-methionine, l-phenylalanine or l-tryptophan) and incubated for 24 h. The previous 24-h culture served

Zhao-Lai Dai; Jing Zhang; Guoyao Wu; Wei-Yun Zhu

2010-01-01

173

Landscape patterns of free amino acids in arctic tundra soils  

Microsoft Academic Search

Concentrations of free amino acids were measured in soils from four major ecosystem types in arctic Alaska. Total free amino acid concentrations were several-fold higher than ammonium (the major form of inorganic nitrogen) in water extracts of soils. The dominant free amino acids in these soils were glycine, aspartic acid, glutamic acid, serine, and arginine. Concentrations of total amino acids

Knut Kielland

1995-01-01

174

Chromatography of Rare Basic Amino Acids.  

National Technical Information Service (NTIS)

L-Ornithine, l-lysine, alpha, gamma-diaminobutyric acid, and alpha, beta-diaminopropionic acid were separated chromatographically on PA 35 in the presence of amino acids normally present in protein hydrolysates or physiological fluids. The resolution of t...

R. W. Longton V. J. Berzinskas A. Y. Balekuian S. B. Needleman

1973-01-01

175

Review of advances in metabolic bioavailability of amino acids  

Microsoft Academic Search

The animal's amino acid requirement and the potential of feedstuffs to supply those amino acids in metabolically available form (amino acid bioavailability) are intertwined. Although standardized ileal amino acid digestibility is currently most widely used as an estimate of dietary protein quality, numerous factors influence these estimates. Slope ratio assays are considered the standard against which other methods of amino

Crystal L. Levesque; Soenke Moehn; Paul B. Pencharz; Ron O. Ball

2010-01-01

176

Molecular Biology: Proteins, Polypeptides, Amino Acids.  

National Technical Information Service (NTIS)

The Cancergram concerns cancer-related biochemical and physicochemical studies of the synthesis, metabolism, structure, and characterization of proteins. This includes absorption and transport of amino acids; the intracellular events in RNA; protein trans...

1982-01-01

177

How to build optically active ? -amino acids  

Microsoft Academic Search

Summary Various methodologies published in the literature dealing witha-amino carboxylic acid asymmetric synthesis are presented in a digest form. In each case, only some recent or most typical works are mentioned.

M. Calmes; J. Daunis

1999-01-01

178

BIOCHEMISTRY: The 22nd Amino Acid  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required. In their Perspective, Atkins and Gesteland discuss the discovery of the 22nd amino acid, pyrrolysine, in Archaea (Hao et al., Srinivasan et al.).

John F. Atkins (University of Utah;Department of Human Genetics); Ray Gesteland (University of Utah;Department of Human Genetics)

2002-05-24

179

Allylic halogenation of unsaturated amino acids.  

PubMed

A range of dehydro amino acid derivatives has been prepared and subjected to halogenation using either molecular bromine or chlorine, or NBS. Allylic halogenation of the unsaturated amino acid side chains occurs through radical bromination with NBS. The procedure is complementary to treatment with chlorine, which also affords allyl halides. This latter and unusual reaction is shown through a deuterium labelling study to proceed via an ionic mechanism. The choice of NBS or chlorine for allyl halide synthesis is shown to depend on the potential to avoid competing reactions, such as halolactonization of leucine derivatives with chlorine, and hydrogen abstraction and bromine incorporation at multiple sites on treatment of isoleucine derivatives with NBS. The synthetic utility of the allyl halides prepared in this study is indicated through the synthesis of a cyclopropyl amino acid derivative and the extension of the carbon skeleton of an amino acid side chain. PMID:12956066

Easton, Christopher J; Edwards, Alison J; McNabb, Stephen B; Merrett, Martin C; O'Connell, Jenny L; Simpson, Gregory W; Simpson, Jamie S; Willis, Anthony C

2003-07-21

180

Advanced biosensors for amino acid detection  

NASA Astrophysics Data System (ADS)

Reported is work directed towards characterizing an advanced biosensor technology compatible for the real time indirect optical detection of amino acids as typified by e-phen-ylalanine, e-doA, E-Tryptophan and related compounds. The technical strategy involves the indirect optical detection of amines and amino acids by monitoring changes induced in the visible spectra of immobilized chromagenic acyclic polyether host molecules to which the amine or amino acid becomes associated. Syntheses are currently proceeding for preparation of chromagenic acyclic polyether host molecules into which selected amino acids will become incorporated, resulting in induced color changes, detectable when these molecular species are immobilized onto a fiber optic. Design and fabrication of synchronous sample-and-hold circuitry for detection of small optical changes from the fiber optic has largely been completed.

Cook, R. L.; Patel, J.; Sammells, A. F.

1989-10-01

181

Molecular Biology: Proteins, Polypeptides, Amino Acids.  

National Technical Information Service (NTIS)

The Cancergram concerns cancer-related biochemical and physicochemical studies of the synthesis, metabolism, structure, and characterization of proteins. This includes absorption and transport of amino acids, the intracellular events in RNA; protein trans...

1984-01-01

182

The Essential Amino Acids of 'Mytilus californianus'.  

National Technical Information Service (NTIS)

In the study, radiometric techniques are used to determine the essential amino acids of the California mussel, Mytilus californianus Conrad, 1837. Few studies of the nutritional requirements of a mollusk have been performed using this approach. The report...

C. Harrison

1975-01-01

183

An amino acid transporter involved in gastric acid secretion.  

PubMed

Gastric acid secretion is regulated by a variety of stimuli, in particular histamine and acetyl choline. In addition, dietary factors such as the acute intake of a protein-rich diet and the subsequent increase in serum amino acids can stimulate gastric acid secretion only through partially characterized pathways. Recently, we described in mouse stomach parietal cells the expression of the system L heteromeric amino acid transporter comprised of the LAT2-4F2hc dimer. Here we address the potential role of the system L amino acid transporter in gastric acid secretion by parietal cells in freshly isolated rat gastric glands. RT-PCR, western blotting and immunohistochemistry confirmed the expression of 4F2-LAT2 amino acid transporters in rat parietal cells. In addition, mRNA was detected for the B(0)AT1, ASCT2, and ATB(0+) amino acid transporters. Intracellular pH measurements in parietal cells showed histamine-induced and omeprazole-sensitive H+-extrusion which was enhanced by about 50% in the presence of glutamine or cysteine (1 mM), two substrates of system L amino acid transporters. BCH, a non-metabolizable substrate and a competitive inhibitor of system L amino acid transport, abolished the stimulation of acid secretion by glutamine or cysteine suggesting that this stimulation required the uptake of amino acids by system L. In the absence of histamine glutamine also stimulated H+-extrusion, whereas glutamate did not. Also, phenylalanine was effective in stimulating H+/K+-ATPase activity. Glutamine did not increase intracellular Ca2+ levels indicating that it did not act via the recently described amino acid modulated Ca2+-sensing receptor. These data suggest a novel role for heterodimeric amino acid transporters and may elucidate a pathway by which protein-rich diets stimulate gastric acid secretion. PMID:16308696

Kirchhoff, Philipp; Dave, Mital H; Remy, Christine; Kosiek, Ortrud; Busque, Stephanie M; Dufner, Matthias; Geibel, John P; Verrey, Francois; Wagner, Carsten A

2005-11-25

184

Lipoic Acid-Dependent Oxidative Catabolism of ?-Keto Acids in Mitochondria Provides Evidence for Branched-Chain Amino Acid Catabolism in Arabidopsis1  

PubMed Central

Lipoic acid-dependent pathways of ?-keto acid oxidation by mitochondria were investigated in pea (Pisum sativum), rice (Oryza sativa), and Arabidopsis. Proteins containing covalently bound lipoic acid were identified on isoelectric focusing/sodium dodecyl sulfate-polyacrylamide gel electrophoresis separations of mitochondrial proteins by the use of antibodies raised to this cofactor. All these proteins were identified by tandem mass spectrometry. Lipoic acid-containing acyltransferases from pyruvate dehydrogenase complex and ?-ketoglutarate dehydrogenase complex were identified from all three species. In addition, acyltransferases from the branched-chain dehydrogenase complex were identified in both Arabidopsis and rice mitochondria. The substrate-dependent reduction of NAD+ was analyzed by spectrophotometry using specific ?-keto acids. Pyruvate- and ?-ketoglutarate-dependent reactions were measured in all three species. Activity of the branched-chain dehydrogenase complex was only measurable in Arabidopsis mitochondria using substrates that represented the ?-keto acids derived by deamination of branched-chain amino acids (Val [valine], leucine, and isoleucine). The rate of branched-chain amino acid- and ?-keto acid-dependent oxygen consumption by intact Arabidopsis mitochondria was highest with Val and the Val-derived ?-keto acid, ?-ketoisovaleric acid. Sequencing of peptides derived from trypsination of Arabidopsis mitochondrial proteins revealed the presence of many of the enzymes required for the oxidation of all three branched-chain amino acids. The potential role of branched-chain amino acid catabolism as an oxidative phosphorylation energy source or as a detoxification pathway during plant stress is discussed.

Taylor, Nicolas L.; Heazlewood, Joshua L.; Day, David A.; Millar, A. Harvey

2004-01-01

185

Amino Acids Mediate Postprandial Jejunal Proabsorption  

Microsoft Academic Search

Ingestion of a meal stimulates small intestinal ion and water transport. Current evidence suggests that this response, termed proabsorption, is primarily mediated by the apical Na+\\/glucose cotransporter. Like glucose, the majority of amino acid absorption occurs by Na+-dependent, secondary active transport. The purpose of this study was to determine the role of amino acid transport in meal-induced jejunal ion and

Oscar J. Hines; Anton J. Bilchik; Stanley W. Ashley; Edward E. Whang; Carson D. Liu; Michael J. Zinner; David W. McFadden

1995-01-01

186

Adsorption of amino acids on hydrophilic surfaces  

Microsoft Academic Search

Sum frequency generation vibrational spectroscopy (SFG) is a powerful tool for in situ investigation of adsorption processes at biologically important solid-liquid interfaces. In this work adsorption of selected amino acids on fused silica, calcium fluoride and titanium dioxide substrates was studied by this technique. SFG spectra taken at the amino acid solution-fused SiO2 interface revealed the lack of formation of

Z. Pászti; T. Keszthelyi; O. Hakkel; L. Guczi

2008-01-01

187

Interactions among the branched-chain amino acids and their effects on methionine utilization in growing pigs: effects on plasma amino- and keto-acid concentrations and branched-chain keto-acid dehydrogenase activity.  

PubMed

The present experiment was designed to elucidate the mechanism of the methionine-sparing effect of excess branched-chain amino acids (BCAA) reported in the previous paper (Langer & Fuller, 2000). Twelve growing gilts (30-35 kg) were prepared with arterial catheters. After recovery, they received for 7 d a semipurified diet with a balanced amino acid pattern. On the 7th day blood samples were taken before (16 h postabsorptive) and after the morning meal (4 h postprandial). The animals were then divided into three groups and received for a further 7 d a methionine-limiting diet (80% of requirement) (1) without any amino acid excess; (2) with excess leucine (50% over requirement); or (3) with excesses of all three BCAA (leucine, isoleucine, valine, each 50% over the requirement). On the 7th day blood samples were taken as in the first period, after which the animals were killed and liver and muscle samples taken. Plasma amino acid and branched-chain keto acid (BCKA) concentrations in the blood and branched-chain keto-acid dehydrogenase (BCKDH; EC 1.2.4.4) activity in liver and muscle homogenates were determined. Compared with those on the balanced diet, pigs fed on methionine-limiting diets had significantly lower (P < 0.05) plasma methionine concentrations in the postprandial but not in the postabsorptive state. There was no effect of either leucine or a mixture of all three BCAA fed in excess on plasma methionine concentrations. Excess dietary leucine reduced (P < 0.05) the plasma concentrations of isoleucine and valine in both the postprandial and postabsorptive states. Plasma concentrations of the BCKA reflected the changes in the corresponding amino acids. Basal BCKDH activity in the liver and total BCKDH activity in the biceps femoris muscle were significantly (P < 0.05) increased by excesses of leucine or all BCAA. PMID:10703464

Langer, S; Scislowski, P W; Brown, D S; Dewey, P; Fuller, M F

2000-01-01

188

Evaluation of amino acids as turfgrass nematicides.  

PubMed

Laboratory experiments revealed that DL-methionine, sodium methionate, potassium methionate, and methionine hydroxyl analog at rates of 224 and 448 kg amino acid/ha reduced the number of Belonolaimus longicaudatus mixed life-stages and Meloidogyne incognita J2 in soil, whereas L-threonine and lysine were not effective in reducing the number of either nematode. Futhermore, greenhouse experiments demonstrated that DL-methionine, sodium methionate, potassium methionate, and methionine hydroxyl analog were equally effective against B. longicaudatus at rates of 112, 224, and 448 kg amino acid/ha, and the highest rate (448 kg amino acid/ha) of all amino acids was more effective in reducing the number of B. longicaudatus than the lower rate. However, phytotoxicity was observed on creeping bentgrass (Agrostis palustris) treated with 448 kg amino acid/ha of methionine hydroxyl analog and DL methionine. In addition, in one of two field experiments on bermudagrass (Cynodon dactylon × C. transvaalensis) turf percentage green cover was increased and the number of B. longicaudatus was reduced by 224 kg amino acid/ha of DL-methionine and potassium methionate compared to untreated controls in one of two trials. PMID:22736861

Zhang, Yun; Luc, John E; Crow, William T

2010-12-01

189

Amino Acid Patterns around Disulfide Bonds  

PubMed Central

Disulfide bonds provide an inexhaustible source of information on molecular evolution and biological specificity. In this work, we described the amino acid composition around disulfide bonds in a set of disulfide-rich proteins using appropriate descriptors, based on ANOVA (for all twenty natural amino acids or classes of amino acids clustered according to their chemical similarities) and Scheffé (for the disulfide-rich proteins superfamilies) statistics. We found that weakly hydrophilic and aromatic amino acids are quite abundant in the regions around disulfide bonds, contrary to aliphatic and hydrophobic amino acids. The density distributions (as a function of the distance to the center of the disulfide bonds) for all defined entities presented an overall unimodal behavior: the densities are null at short distances, have maxima at intermediate distances and decrease for long distances. In the end, the amino acid environment around the disulfide bonds was found to be different for different superfamilies, allowing the clustering of proteins in a biologically relevant way, suggesting that this type of chemical information might be used as a tool to assess the relationship between very divergent sets of disulfide-rich proteins.

Marques, Jose R. F.; da Fonseca, Rute R.; Drury, Brett; Melo, Andre

2010-01-01

190

40 CFR 721.1705 - Benzoic acid, 3-amino-, diazotized, coupled with 6-amino-4-hydroxy-2-naphthalenesulfonic acid...  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Benzoic acid, 3-amino-, diazotized, coupled...Chemical Substances § 721.1705 Benzoic acid, 3-amino-, diazotized, coupled...substance generically identified as benzoic acid, 3-amino-, diazotized,...

2009-07-01

191

40 CFR 721.1705 - Benzoic acid, 3-amino-, diazotized, coupled with 6-amino-4-hydroxy-2-naphthalenesulfonic acid...  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Benzoic acid, 3-amino-, diazotized, coupled...Chemical Substances § 721.1705 Benzoic acid, 3-amino-, diazotized, coupled...substance generically identified as benzoic acid, 3-amino-, diazotized,...

2010-07-01

192

Anorexia in rats caused by a valine-deficient diet is not ameliorated by systemic ghrelin treatment  

Microsoft Academic Search

Rodents exhibit aversive behavior toward a diet that lacks at least one of the essential amino acids. We sought to determine whether the particular form of anorexia caused by such diets could be ameliorated by the administration of orexigenic peptides while simultaneously analyzing the neural mechanisms underlying anorexia. Rats were fed a valine-deficient diet, which induced severe anorexia (reducing food

S. Goto; K. Nagao; M. Bannai; M. Takahashi; K. Nakahara; K. Kangawa; N. Murakami

2010-01-01

193

Amino acid requirements in humans: with a special emphasis on the metabolic availability of amino acids  

Microsoft Academic Search

Due to advances made in the development of stable isotope based carbon oxidation methods, the determination of amino acid\\u000a requirements in humans has been an active area of research for the past 2 decades. The indicator amino acid oxidation (IAAO)\\u000a method developed in our laboratory for humans has been systematically applied to determine almost all indispensable amino\\u000a acid requirements in

Rajavel Elango; Ronald O. Ball; Paul B. Pencharz

2009-01-01

194

Cloning a Plant Amino Acid Transporter by Functional Complementation of a Yeast Amino Acid Transport Mutant  

Microsoft Academic Search

Amino acids are transported across the plasma membrane of plant cells by proton-amino acid symports. We report here the successful cloning of a neutral amino acid carrier by functional complementation. A histidine transport deletion mutant of Saccharomyces cerevisiae was transformed with an Arabidopsis thaliana cDNA library constructed in a yeast expression vector. Forty transformants, out of 10^5, allowed growth on

Li-Chu Hsu; Tzyy-Jen Chiou; Lishan Chen; Daniel R. Bush

1993-01-01

195

Plasma amino acids in four models of experimental liver injury in rats.  

PubMed

We studied the plasma amino acid profiles in four models of hepatic injury in rats. In partially hepatectomized rats (65% of liver was removed) we observed significant increase of aromatic amino acids (AAA; i.e. tyrosine and phenylalanine), taurine, aspartate, threonine, serine, asparagine, methionine, ornithine and histidine. Branched-chain amino acids (BCAA; i.e. valine, leucine and isoleucine) concentrations were unchanged. In ischemic and carbon tetrachloride acute liver damage we observed extreme elevation of most of amino acids (BCAA included) and very low concentration of arginine. In carbon tetrachloride induced liver cirrhosis we observed increased levels of AAA, aspartate, asparagine, methionine, ornithine and histidine and decrease of BCAA, threonine and cystine. BCAA/AAA ratio decreased significantly in partially hepatectomized and cirrhotic rats and was unchanged in ischemic and acute carbon tetrachloride liver damage. We conclude that a high increase of most of amino acids is characteristic of fulminant hepatic necrosis; decreased BCAA/AAA ratio is characteristic of liver cirrhosis; and decrease of BCAA/AAA ratio may not be used as an indicator of the severity of hepatic parenchymal damage. PMID:24178537

Hole?ek, M; Mráz, J; Tilšer, I

1996-09-01

196

Kinetic Relations of the Na-Amino Acid Interaction at the Mucosal Border of Intestine  

PubMed Central

The relation between unidirectional influxes of Na and amino acids across the mucosal border of rabbit ileum was studied under a variety of conditions. At constant Na concentration in the mucosal bathing solution, amino acid influx followed Michaelis-Menten kinetics permitting determination of maximal influx and the apparent Michaelis constant, Kt. Reduction in Na concentration, using choline as substitute cation, caused an increase in Kt for alanine but had no effect on maximal alanine influx. The reciprocal of Kt was a linear function of Na concentration. Similar results were obtained for valine and leucine and these amino acids competitively inhibited alanine influx both in the presence and in the absence of Na. These results lead to a model for the transport system which involves combination of Na and amino acid with a single carrier or site leading to penetration of both solutes. The model predicts that alanine should cause an increase in Na influx and the ratio of this extra Na flux to alanine flux should vary with Na concentration. The observed relation agreed closely with predicted values for Na concentrations from 5 to 140 mM. These results support the hypothesis that interactions between Na and amino acid transport depend in part on a common entry mechanism at the mucosal border of the intestine.

Curran, Peter F.; Schultz, Stanley G.; Chez, Ronald A.; Fuisz, Robert E.

1967-01-01

197

Cassava interspecific hybrids with increased protein content and improved amino acid profiles.  

PubMed

Cassava (Manihot esculenta) is a principal food for large populations of poor people in the tropics and subtropics. Its edible roots are poor in protein and lack several essential amino acids. Interspecific hybrids may acquire high protein characteristics from wild species. We analyzed 19 hybrids of M. esculenta with its wild relative, M. oligantha, for crude protein, amino acid profile, and total cyanide. Some hybrids produced roots with high protein content of up to 5.7%, while the common cultivar that we examined had just 2.3% crude protein. The essential amino acids alanine, phenylalanine, and valine were detected in the hybrids. The sulfur-containing amino acids cysteine and methionine were found at relatively high concentrations in the roots of 4 hybrids. The proportion of lysine in one hybrid was 20 times higher than in the common cultivar. The levels of total cyanide ranged from 19.73 to 172.56 mg/kg and most of the roots analyzed were classified as "non-toxic" and "low toxic". Furthermore, 2 progenies showed reasonable levels of cyanide, but higher protein content and amino acid profile more advantageous than the common cassava. PMID:23661446

Gomes, P T C; Nassar, N M A

2013-04-12

198

Synthesis of biodegradative threonine dehydratase in Escherichia coli: role of amino acids, electron acceptors, and certain intermediary metabolites.  

PubMed Central

The specific activity of inducible biodegradative threonine dehydratase (EC 4.2.1.16) in Escherichia coli K-12 increased significantly when the standard tryptone-yeast extract medium or a synthetic mixture of 18 L-amino acids was supplemented with 10 mM KNO3 or 50 mM fumarate and with 4 mM cyclic AMP. In absolute terms, almost four times as much enzyme was produced in the amino acid medium as in the tryptone-yeast extract medium. Enzyme induction in the amino acid medium was sensitive to catabolite repression by glucose, gluconate, glycerol, and pyruvate. An analysis of amino acid requirements for enzyme induction showed that a combination of only four amino acids, threonine, serine, valine, and isoleucine, produced high levels of threonine dehydratase provided that both fumarate and cyclic AMP were present. Immunochemical data revealed that the enzyme synthesized in the presence of these four amino acids was indistinguishable from that produced in the tryptone-yeast extract or the medium with 18 amino acids. We interpret these results to mean that not the amino acids themselves but some metabolites derived anaerobically in reactions involving an electron acceptor may function as putative regulatory molecule(s) in the anaerobic induction of this enzyme. Images

Hobert, E H; Datta, P

1983-01-01

199

[Dynamics of the amino acid composition of the medium during cultivation of isolated organs by the directed perfusion method].  

PubMed

The dynamics of the amino acid composition of the medium under conditions of adequate perfusion of the isolated organs of a dog (sternum, kidney and liver) was studied. It was found that after a 6-hour perfusion of the complex of organs the amount in the perfusion medium of such amino acids as histidine, lysine, alanine, considerably increased, whereas the amount of arginine, serine, aspartic acid, threonine with glutamine, isoleucine, proline, leucine and valine decreased as compared with their initial concentration. The dynamics of the amino acid medium composition during a 4-hour perfusion was studied in experiments with the isolated sternum. The concentration of alanine, lysine and histidine increased in the medium. At the same time there was seen a decrease in the concentration of serine, aspartic acid, isoleucine, tyrosine and phenyl-alanine. PMID:1227646

Barashkov, V A; Gitel'zon, I I; Nefedov, V P; Trubachev, I N

1975-07-01

200

Molecular interactions of ?-amino acids insight into aqueous ?-cyclodextrin systems.  

PubMed

Qualitative and quantitative analysis of molecular interaction prevailing in glycine, L-alanine, L-valine and aqueous solution of ?-cyclodextrin (?-CD) have been probed by thermophysical properties. Density (?), viscosity (?), and ultrasonic speed (u) measurements have been reported at different temperatures. The extent of interaction (solute-solvent interaction) is expressed in terms of the limiting apparent molar volume ([Formula: see text]), viscosity B-coefficient and limiting apparent molar adiabatic compressibility ([Formula: see text]). The changes on the enthalpy ([Formula: see text]) and entropy ([Formula: see text]) of the encapsulation analysis give information about the driving forces governing the inclusion. The temperature dependence behaviour of partial molar quantities and group contributions to partial molar volumes has been determined for the amino acids. The trends in transfer volumes, [Formula: see text], have been interpreted in terms of solute-cosolute interactions based on a cosphere overlap model. The role of the solvent (aqueous solution of ?-CD) and the contribution of solute-solute and solute-solvent interactions to the solution complexes have also been analyzed through the derived properties. PMID:23760675

Ekka, Deepak; Roy, Mahendra Nath

2013-06-13

201

Aromatic amino acid transport in Yersinia pestis.  

PubMed Central

The uptake and concentration of aromatic amino acids by Yersinia pestis TJW was investigated using endogenously metabolizing cells. Transport activity did not depend on either protein synthesis or exogenously added energy sources such as glucose. Aromatic amino acids remained as the free, unaltered amino acid in the pool fraction. Phenylalanine and tryptophan transport obeyed Michaelis-Menten-like kinetics with apparent Km values of 6 x 10(-7) to 7.5 x 10(-7) and 2 x 10(-6) M, respectively. Tyrosine transport showed biphasic concentration-dependent kinetics that indicated a diffusion-like process above external tyrosine concentrations of 2 x 10(-6) M. Transport of each aromatic amino acid showed different pH and temperature optima. The pH (7.5 TO8) and temperature (27 C) optima for phenylalanine transport were similar to those for growth. Transport of each aromatic amino acid was characterized by Q10 values of approximately 2. Cross inhibition and exchange experiments between the aromatic amino acids and selected aromatic amino acid analogues revealed the existence of three transport systems: (i) tryptophan specific, (ii) phenylalanine specific with limited transport activity for tyrosine and tryptophan, and (iii) general aromatic system with some specificity for tyrosine. Analogue studies also showed that the minimal stereo and structural features for phenylalanine recognition were: (i) the L isomer, (ii) intact alpha amino and carboxy group, and (iii) unsubstituted aromatic ring. Aromatic amino acid transport was differentially inhibited by various sulfhydryl blocking reagents and energy inhibitors. Phenylalanine and tyrosine transport was inhibited by 2,4-dinitrophenol, potassium cyanide, and sodium azide. Phenylalanine transport showed greater sensitivity to inhibition by sulfhydryl blocking reagents, particularly N-ethylmaleimide, than did tyrosine transport. Tryptophan transport was not inhibited by either sulfhydryl reagents or sodium azide. The results on the selective inhibition of aromatic amino acid transport provide additional evidence for multiple transport systems . These results further suggest both specific mechanisms for carrier-mediated active transport and coupling to metabolic energy.

Smith, P B; Montie, T C

1975-01-01

202

Amino acid survival in large cometary impacts  

NASA Astrophysics Data System (ADS)

A significant fraction of the Earth's prebiotic volatile inventory may have been delivered by asteroidal and cometary impacts during the period of heavy bombardment. The realization that comets are particularly rich in organic material seemed to strengthen this suggestion. Previous modeling studies, however, indicated that most organics would be entirely destroyed in large comet and asteroid impacts. The availability of new kinetic parameters for the thermal degradation of amino acids in the solid phase made it possible to readdress this question. We present the results of new high-resolution hydrocode simulations of asteroid and comet impact coupled with recent experimental data for amino acid pyrolysis in the solid phase. Differences due to impact velocity as well as projectile material have been investigated. Effects of angle of impacts were also addressed. The results suggest that some amino acids would survive the shock heating of large (kilometer-radius) cometary impacts. At the time of the origins of life on Earth, the steady-state oceanic concentration of certain amino acids (like aspartic and glutamic acid) delivered by comets could have equaled or substantially exceeded that due to Miller-Urey synthesis in a carbon dioxide-rich atmosphere. Furthermore, in the unlikely case of a grazing impact (impact angle around 5 degrees from the horizontal) an amount of some amino acids comparable to that due to the background steady-state production or delivery would be delivered to the early Earth.

Pierazzo, E.; Chyba, C. F.

1999-11-01

203

Purification and properties of a binding protein for branched-chain amino acids in Pseudomonas aeruginosa.  

PubMed Central

A binding protein for branched-chain amino acids was purified to a homogeneous state from shock fluid of Pseudomonas aeruginosa PML14. It was a monomeric protein with an apparent molecular weight of 4.3 x 10(4) or 4.0 x 10(4) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis or gel filtration, respectively. The isoelectric point was determined to be pH 4.1 by electrofocusing. Amino acid analysis of the protein showed that aspartic acid, glutamic acid, glycine, and alanine were major components and that the protein contained only one residue each of tryptophan and cysteine per molecule. The binding protein contained no sugar. The binding activity of the protein was specific for the branched-chain amino acids. The protein also bound alanine and threonine with lower affinity. The dissociation constants of this protein for leucine, isoleucine, and valine were found to be 0.4, 0.3, and 0.5 microM, respectively. Mutants defective in the production of the binding protein were identified among the mutants deficient in a transport system for branched-chain amino acids (LIV-I). The revertants from these mutants to LIV-I-positive phenotype simultaneously recovered normal levels of the binding protein. These findings suggest strongly the association of the binding protein with the LIV-I transport system. Images

Hoshino, T; Kageyama, M

1980-01-01

204

Branched-chain amino acids complex inhibits melanogenesis in B16F0 melanoma cells.  

PubMed

Present study was investigated the effect of each or complex of three branched-chain amino acids (BCAAs; isoleucine, leucine, and valine) on melanin production in B16F0 melanoma cells treated with various concentrations (1-16?mM) for 72?h. Among the 20 amino acids, lysine and glycine showed the highest activities of DPPH radical scavenging and mushroom tyrosinase inhibition, respectively. Each and combination of BCAAs reduced melanogenesis in a concentration-dependent manner without any morphological changes and cell viability in melanoma cells. Present study was also investigated the inhibitory effects of each or complex of BCAAs at each 10?mM concentration on the 100 ?M IBMX-mediated stimulation of melanogenesis in melanoma cells for 72?h and found that IBMX treatment was stimulated to enhance melanin synthesis and that the complex of BCAAs was the most effectively inhibited in the melanin amounts of cellular and extracellular and the whitening the cell pellet. When the inhibitory effect of BCAAs on tyrosinase was examined by intracellular tyrosinase assay, both isoleucine and valine exhibit slightly inhibition, but leucine and combination of BCAAs did not inhibit the cell-derived tyrosinase activity. Present study demonstrated that complex of BCAAs inhibited melanin production without changes intercellular tyrosinase activity. Thus, the complex of BCAAs may be used in development of safe potentially depigmenting agents. PMID:21854182

Cha, Jae-Young; Yang, Hyun-Ju; Moon, Hyung-In; Cho, Young-Su

2011-08-19

205

Homocysteine Toxicity in Escherichia coli Is Caused by a Perturbation of Branched-Chain Amino Acid Biosynthesis  

PubMed Central

In Escherichia coli the sulfur-containing amino acid homocysteine (Hcy) is the last intermediate on the methionine biosynthetic pathway. Supplementation of a glucose-based minimal medium with Hcy at concentrations greater than 0.2 mM causes the growth of E. coli Frag1 to be inhibited. Supplementation of Hcy-treated cultures with combinations of branched-chain amino acids containing isoleucine or with isoleucine alone reversed the inhibitory effects of Hcy on growth. The last intermediate of the isoleucine biosynthetic pathway, ?-keto-?-methylvalerate, could also alleviate the growth inhibition caused by Hcy. Analysis of amino acid pools in Hcy-treated cells revealed that alanine, valine, and glutamate levels are depleted. Isoleucine could reverse the effects of Hcy on the cytoplasmic pools of valine and alanine. Supplementation of the culture medium with alanine gave partial relief from the inhibitory effects of Hcy. Enzyme assays revealed that the first step of the isoleucine biosynthetic pathway, catalyzed by threonine deaminase, was sensitive to inhibition by Hcy. The gene encoding threonine deaminase, ilvA, was found to be transcribed at higher levels in the presence of Hcy. Overexpression of the ilvA gene from a plasmid could overcome Hcy-mediated growth inhibition. Together, these data indicate that in E. coli Hcy toxicity is caused by a perturbation of branched-chain amino acid biosynthesis that is caused, at least in part, by the inhibition of threonine deaminase.

Tuite, Nina L.; Fraser, Katy R.; O'Byrne, Conor P.

2005-01-01

206

Separation of L-valine from fermentation broths using a supported liquid membrane.  

PubMed

A carrier-mediated counter transport process is proposed to separate and to purify an amino acid produced by microbial fermentation. The case of L-valine permeation through a liquid membrane, constituted by a solution of Aliquat 336 in decanol and supported by a hydrophobic microporous membrane, is reported. A mathematical model was developed to estimate distribution coefficients and permeabilities and to predict the influence of hydrodynamic and pH conditions on supported liquid membrane (SLM) performances. Optimum conditions for the transport and the concentration of valine were achieved with synthetic aqueous valine solutions. Series of experiments on fermentation broths, where molasses and biomass contents were varied, permitted pointing out the role of the broth composition on the kinetics and yields of separation. The selectivity of transport of valine by an Aliquat 336/decanol liquid membrane was about 10 toward molasses dyes, 100 toward glucose, and beyond 1000 toward sucrose. This allowed us to achieve the recovery and one step of purification of the product in a single operation. The stability of the Aliquat 336/decanol liquid membrane was sufficient to ensure a selective transport of valine during a continuous run lasting 18 days. PMID:18592501

Deblay, P; Minier, M; Renon, H

1990-01-20

207

Production of L-(1-/sup 11/C)valine by HPLC resolution  

SciTech Connect

Based on a recently developed analytical technique, preparative high-performance liquid chromatographic (HPLC) resolution of DL-(1-/sup 11/C)valine has been achieved. A conventional reverse-phase HPLC column and a chiral mobile phase (aqueous solution of L-proline, cupric acetate, and sodium acetate) were used. The copper can be removed from the L-valine fraction by precipitation as the sulfide, and final purification by cation-exchange chromatography yields L-(1-/sup 11/C)valine in a form that is acceptable for clinical positron tomographic studies. This purification method does not remove the L-proline introduced in the resolution process, but added L-proline did not affect the tissue distribution of L-(1-/sup 14/C)valine in rats. We have produced up to 60 mCi of L-(1-/sup 11/C)valine in an overall synthesis and resolution time of 50 min. This procedure should be adaptable to the rapid resolution of other C-/sup 11/-labeled amino acid racemates.

Washburn, L.C.; Sun, T.T.; Byrd, B.L.; Callahan, A.P.

1982-01-01

208

Production of L-(1-/sup 11/C)valine by HPLC resolution  

SciTech Connect

Based on a recently developed analytical technique, preparative high-performance liquid chromatographic (HPLC) resolution of DL-(1-/sup 11/C)valine has been achieved. A conventional reverse-phase HPLC column and a chiral mobile phase (aqueous solution of L-proline, cupric acetate, and sodium acetate) were used. The copper can be removed from the L-valine fraction by precipitation as the sulfide, and final purification by cation-exchange chromatography yields L-(1-/sup 11/C)valine in a form that is acceptable for clinical positron tomographic studies. This purification method does not remove the L-proline introduced in the resolution process, but added L-proline did not affect the tissue distribution of L-(1-/sup 14/C)valine in rats. We have produced up to 60 mCi of L-(1-/sup 11/C)valine in an overall synthesis and resolution time of 50 min. This procedure should be adapable to the rapid resolution of other C-11-labeled amino acid racemates.

Washburn, L.C.; Sun, T.T.; Byrd, B.L.; Callahan, A.P.

1982-01-01

209

Amino Acids Profiles in Biological Media  

SciTech Connect

An accurate analytical method was developed to determine amino acids in some biological specimens by GC/MS technique. Stable isotopes provide useful tools for a variety of studies, offering ideal internal standards in quantitative information. Isotopic dilution gas chromatography--mass spectrometry (ID-GC/MS) is the techniques used for quantitative analysis of compounds labeled with stable isotopes. A Trace DSQ Thermo Finnigan quadrupole mass spectrometer coupled with a Trace GC was used. Amino acids were separated on a Rtx-5 MS capillary column, 30 mx0.25 mm, 0.25 {mu}m film thickness, using a temperature program from 50 deg. C, 1 min, 6 deg. C/min at 100 deg. C, 4 deg. C/min at 200 deg. C, 20 deg. C/min at 300 deg. C, (3 min). The transfer line temperature was 250 deg. C, the injector temperature 200 deg. C and ion source temperature 250 deg. C; splitter: 10:1. Electron energy was 70 eV and emission current, 100 {mu}A. The amino acids were purified on a Dowex 50W-W8 exchange resin and were derivatized in a procedure following two steps to obtain trifluoroacetyl butyl esters. The identification of amino acids was obtained by using NIST library but also by using amino acid standards.

Iordache, A. [National R and D Institute of Cryogenics and Isotopic Technologies-ICSI Rm. Valcea, 4 Uzinei St., Rm. Valcea, 240050 (Romania); Horj, E.; Morar, S.; Cozar, O.; Culea, M. ['Babes-Bolyai' University, 1 M. Kogalniceanu St., Cluj-Napoca, 400084 (Romania); Ani, A. R. [University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca-USAMV, 3-5 Manastur St., 400372 Cluj-Napoca (Romania); Mesaros, C. [University of Medicine and Pharmacy, 38 Gh. Marinescu St., 540000, Targu Mures (Romania)

2010-08-04

210

Branched Chain Amino Acid Metabolism in the Biosynthesis of Lycopersicon pennellii Glucose Esters.  

PubMed

Lycopersicon pennellii Corr. (D'Arcy) an insect-resistant, wild tomato possesses high densities of glandular trichomes which exude a mixture of 2,3,4-tri-O-acylated glucose esters that function as a physical impediment and feeding deterrent to small arthropod pests. The acyl moieties are branched C(4) and C(5) acids, and branched and straight chain C(10), C(11), and C(12) acids. The structure of the branched acyl constituents suggests that the branched chain amino acid biosynthetic pathway participates in their biosynthesis. [(14)C]Valine and deuterated branched chain amino acids (and their oxo-acid derivatives) were incorporated into branched C(4) and C(5) acid groups of glucose esters by a process of transamination, oxidative decarboxylation and subsequent acylation. C(4) and C(5) branched acids were elongated by two carbon units to produce the branched C(10)-C(12) groups. Norvaline, norleucine, allylglycine, and methionine also were processed into acyl moieties and secreted from the trichomes as glucose esters. Changes in the acyl composition of the glucose esters following sulfonylurea herbicide administration support the participation of acetohydroxyacid synthetase and the other enzymes of branched amino acid biosynthesis in the production of glucose esters. PMID:16667654

Walters, D S; Steffens, J C

1990-08-01

211

Branched chain amino acid metabolism in the biosynthesis of Lycopersicon pennellii glucose esters  

SciTech Connect

Lycopersicon pennellii Corr. (D'Arcy) an insect-resistant, wild tomato possesses high densities of glandular trichomes which exude a mixture of 2,3,4-tri-O-acylated glucose esters that function as a physical impediment and feeding deterrent to small arthropod pests. The acyl moieties are branched C{sub 4} and C{sub 5} acids, and branched and straight chain C{sub 10}, C{sub 11}, and C{sub 12} acids. The structure of the branched acyl constituents suggests that the branched chain amino acid biosynthetic pathway participates in their biosynthesis. ({sup 14}C)Valine and deuterated branched chain amino acids (and their oxo-acid derivatives) were incorporated into branched C{sub 4} and C{sub 5} acid groups of glucose esters by a process of transamination, oxidative decarboxylation and subsequent acylation. C{sub 4} and C{sub 5} branched acids were elongated by two carbon units to produce the branched C{sub 10}-C{sub 12} groups. Norvaline, norleucine, allylglycine, and methionine also were processed into acyl moieties and secreted from the trichomes as glucose esters. Changes in the acyl composition of the glucose esters following sulfonylurea herbicide administration support the participation of acetohydroxyacid synthetase and the other enzymes of branched amino acid biosynthesis in the production of glucose esters.

Walters, D.S.; Steffens, J.C. (Cornell Univ., Ithaca, NY (USA))

1990-08-01

212

Branched Chain Amino Acid Metabolism in the Biosynthesis of Lycopersicon pennellii Glucose Esters 1  

PubMed Central

Lycopersicon pennellii Corr. (D'Arcy) an insect-resistant, wild tomato possesses high densities of glandular trichomes which exude a mixture of 2,3,4-tri-O-acylated glucose esters that function as a physical impediment and feeding deterrent to small arthropod pests. The acyl moieties are branched C4 and C5 acids, and branched and straight chain C10, C11, and C12 acids. The structure of the branched acyl constituents suggests that the branched chain amino acid biosynthetic pathway participates in their biosynthesis. [14C]Valine and deuterated branched chain amino acids (and their oxo-acid derivatives) were incorporated into branched C4 and C5 acid groups of glucose esters by a process of transamination, oxidative decarboxylation and subsequent acylation. C4 and C5 branched acids were elongated by two carbon units to produce the branched C10-C12 groups. Norvaline, norleucine, allylglycine, and methionine also were processed into acyl moieties and secreted from the trichomes as glucose esters. Changes in the acyl composition of the glucose esters following sulfonylurea herbicide administration support the participation of acetohydroxyacid synthetase and the other enzymes of branched amino acid biosynthesis in the production of glucose esters.

Walters, Donald S.; Steffens, John C.

1990-01-01

213

Arsenic affects essential and non-essential amino acids differentially in rice grains: inadequacy of amino acids in rice based diet.  

PubMed

Recent breakthroughs in rice arsenic (As) research demonstrate that As accumulation significantly affects trace nutrients in rice grain. In the present study we analyzed the amino acid (AA) profile of sixteen rice genotypes differing in grain As accumulation, grown at three sites with different soil As concentrations, in ascending order, Chinsurahamino acids (EAAs) which were more prominent in high As accumulating rice genotypes (HAARGs). Conversely, non-essential amino acids (NEAAs) showed an increase in low As accumulating rice genotypes (LAARGs) but a decrease in HAARGs. EAAs like isoleucine, leucine, valine, phenylalanine, and tyrosine also decreased in most of the genotypes. NEAAs like glutamic acid, glycine, proline, and histidine showed an increase in all LAARGs. Likewise, sulfur containing AAs (methionine and cysteine) increased in LAARGs but decreased in HAARGs. Among NEAAs in HAARGs, only arginine and serine showed some induction in most of the genotypes. At the highest As site (Birnagar) total EAAs and NEAAs show significant reduction in HAARGs compared to LAARGs. The study concluded that As accumulation in rice grain alters EAAs and NEAAs differentially, and reduction was more pronounced in HAARGs than in LAARGs. Thus, As tainted rice limits required levels of AAs in rice based diets and therefore cannot alone fulfill the recommended daily intake (RDI) of AAs. PMID:22664651

Dwivedi, Sanjay; Mishra, Aradhana; Tripathi, Preeti; Dave, Richa; Kumar, Amit; Srivastava, Sudhakar; Chakrabarty, Debasis; Trivedi, Pabodh Kumar; Adhikari, Bijan; Norton, Gareth John; Tripathi, Rudra Deo; Nautiyal, Chandra Shekhar

2012-06-02

214

The nucleotide sequence of HLA-B{sup *}2704 reveals a new amino acid substitution in exon 4 which is also present in HLA-B{sup *}2706  

SciTech Connect

The HLA-B27 subtype HLA-B{sup *}2704 is virtually absent in Caucasians but common in Orientals, where it is associated with ankylosing spondylitis. The amino acid sequence of HLA-B{sup *}2704 has been established by peptide mapping and was shown to differ by two amino acids from HLA-B{sup *}2705, HLA-B{sup *}2704 is characterized by a serine for aspartic acid substitution at position 77 and glutamic acid for valine at position 152. To date, however, no nucleotide sequence confirming these changes at the DNA level has been published. 13 refs., 2 figs.

Rudwaleit, M.; Bowness, P.; Wordsworth, P. [John Radcliffe Hospital, Oxford (United Kingdom)

1996-12-31

215

Permeability of membranes to amino acids and modified amino acids: Mechanisms involved in translocation  

Microsoft Academic Search

The amino acid permeability of membranes is of interest because they are one of the key solutes involved in cell function. Membrane permeability coefficients (P) for amino acid classes, including neutral, polar, hydrophobic, and charged species, have been measured and compared using a variety of techniques. Decreasing lipid chain length increased permeability slightly (5-fold), while variations in pH had only

A. C. Chakrabarti

1994-01-01

216

Screening for amino acid disorders by thin-layer chromatography of the dansyl amino acids  

Microsoft Academic Search

Summary A procedure is described for the screening of disorders of amino acid metabolism or tranpsort. The amino acids and other reactive constituents present in a small volume of deproteinized plasma or urine are derivatized with dansyl chloride. Desalting or concentrating of urine is not required. The fluorescent derivatives are separated by two-dimensional thin-layer chromatography and visualized by ultraviolet radiation.

James C. Wesenberg; Jacqueline E. Walpole

1980-01-01

217

Epidermal growth factor (EGF) increases the renal amino acid transport capacity in amino acid loaded rats  

Microsoft Academic Search

Summary In anaesthetized adult female rats, the influence of epidermal growth factor (EGF) on renal amino acid handling was investigated in glutamine, arginine (both 50 mg\\/100 g b. wt. per hour), or alanine (90 mg\\/ 100 g b. wt. per hour) loaded animals. Continuous infusions of the three amino acids were followed by an increase in the fractional excretion (FE)

Christian Fleck; J. Pertsch

1998-01-01

218

21 CFR 172.320 - Amino acids.  

Code of Federal Regulations, 2013 CFR

...Monohydrochloride Monopotassium L -glutamate L-Tyrosine L-Valine (2) As found in âSpecifications and Criteria for Biochemical Compounds,â NAS/NRC Publication, 3rd Ed. (1972), which is incorporated by reference (Copies are...

2013-04-01

219

Evolutionary changes reflected by the cellular amino acid composition  

Microsoft Academic Search

Summary Comparison of the amino acid composition of cell-proteins using 17 amino acids has been used to investigate the biological evolution of organisms such as bacteria, blue-green alga, green alga, fungi, slime mold, protozoa and vertebrates. The degree of difference in the amino acid ratios between any two groups reflects the degree of divergency in biological evolution. The amino acid

K. Sorimachi

1999-01-01

220

The amino acid composition of mammalian and bacterial cells  

Microsoft Academic Search

Summary High performance liquid chromatography was used to analyze the amino acid composition of cells. A total of 17 amino acids was analyzed. This method was used to compare the amino acid compositions of the following combinations: primary culture and established cells, normal and transformed cells, mammalian and bacterial cells, andEscherichia coli andStaphylococcus aureus. The amino acid compositions of mammalian

T. Okayasu; M. Ikeda; K. Akimoto; K. Sorimachi

1997-01-01

221

Amino Acid Profiles of Bivalve Mollusks from Beibu Gulf, China  

Microsoft Academic Search

Three bivalve mollusks—clam (Meretrix meretrix), oyster (Crassostrea rivularis), and paphia (Paphia papilionacea) from the Beibu Gulf, China—were analyzed for amino acid profile. Essential amino acids were used for nutritional quality evaluation, and free amino acids were used for taste impact evaluation. The amino acid compositions of the mollusks were quite similar; however, the contents of glycine, alanine, and tryptophan were

De-Wei Chen; Jian Su; Xiao-Ling Liu; Dong-Mei Yan; Ying Lin; Wei-Ming Jiang; Xiao-Han Chen

2012-01-01

222

Amino Acid Profiles of Bivalve Mollusks from Beibu Gulf, China  

Microsoft Academic Search

Three bivalve mollusks, clam (Meretrix meretrix), oyster (Crassostrea rivularis), and paphia (Paphia papilionacea) from the Beibu Gulf, China, were analyzed for amino acid profile. Essential amino acids were used for nutritional quality evaluation, and free amino acids were used for taste impact evaluation. The amino acid compositions of the mollusks were quite similar; however, the contents of glycine, alanine, and

De-Wei Chen; Jian Su; Xiao-Ling Liu; Dong-Mei Yan; Ying Lin; Wei-Ming Jiang; Xiao-Han Chen

2011-01-01

223

Killing of intraerythrocytic Plasmodium falciparum by lysosomotropic amino acid esters  

Microsoft Academic Search

Esters of amino acids are known to penetrate into cells by simple diffusion. Subsequently, they are hydrolyzed by hydrolases to release the parent amino acid. Due to the abundance of hydrolases in phagolysosomes, amino acids accumulate, there because the rate of influx and hydrolysis exceed the rate of amino acid efflux through specific carriers. The osmotic effect of this accumulation

Miriam Krugliak; Jianmin Zhang; Edna Nissani; Sonia Steiner-Mordoch; Hagai Ginsburg

2003-01-01

224

AAindex: amino acid index database, progress report 2008  

Microsoft Academic Search

AAindex is a database of numerical indices repre- senting various physicochemical and biochemical properties of amino acids and pairs of amino acids. We have added a collection of protein contact potentials to the AAindex as a new section. Accordingly AAindex consists of three sections now: AAindex1 for the amino acid index of 20 numerical values, AAindex2 for the amino acid

Shuichi Kawashima; Piotr Pokarowski; Maria Pokarowska; Andrzej Kolinski; Toshiaki Katayama; Minoru Kanehisa

2008-01-01

225

Renal Transport of Endogenous Amino Acids  

Microsoft Academic Search

Repeated adminisatration of triiodothyronine (T3, 20 ?g\\/l00 g b.w., once daily for 3 days) or dexamethasone (60 ?g\\/l00 g b.w., once daily for 3 days) caused significant changes of amino acid plasma concentrations in young (10 days old) and adult rats (2 months old). After treatment with T3, in young animals concentrations of ?-alanine, aspartic acid, glutamic acid, ornithine, asparagine,

Ch. Fleck

1992-01-01

226

An analysis of intron positions in relation to nucleotides, amino acids, and protein secondary structure.  

PubMed

We present an analysis of intron positions in relation to nucleotides, amino acid residues, and protein secondary structure. Previous work has shown that intron sites in proteins are not randomly distributed with respect to secondary structures. Here we show that this preference can be almost totally explained by the nucleotide bias of splice site machinery, and may well not relate to protein stability or conformation at all. Each intron phase is preferentially associated with its own set of residues: phase 0 introns with lysine, glutamine, and glutamic acid before the intron, and valine after; phase 1 introns with glycine, alanine, valine, aspartic acid, and glutamic acid; and phase 2 introns with arginine, serine, lysine, and tryptophan. These preferences can be explained principally on the basis of nucleotide bias at intron locations, which is in accordance with previous literature. Although this work does not prove that introns are inserted into genomes at specific proto-splice sites, it shows that the nucleotide bias surrounding introns, however it originally occurred, explains the observed correlations between introns and protein secondary structure. PMID:16616935

Whamond, Gordon S; Thornton, Janet M

2006-03-29

227

Early parenteral feeding of amino acids.  

PubMed Central

Serial 24 hour balance studies of nitrogen and energy were carried out over 10 days in two groups of ventilator dependent preterm infants, of comparable weight and gestational age. In one group (n = 10) a parenteral amino acid source (Vamin 9) was started within 24 hours of birth, and in the other group (n = 11) it was not started until 72 hours. The feeding protocol was otherwise identical. The nitrogen intake (286 compared with 21 mg/kg/day), energy intake (188 compared with 151 kJ), and nitrogen retention (120 compared with -133 mg/kg/day), were all significantly higher during the first three days of life in the group in which the amino acid solution was started early. There were no differences by 7-10 days. The early introduction of amino acids improves the early nutritional state of sick preterm infants.

Saini, J; MacMahon, P; Morgan, J B; Kovar, I Z

1989-01-01

228

Combinatorial codon-based amino acid substitutions  

PubMed Central

Twenty Fmoc-protected trinucleotide phosphoramidites representing a complete set of codons for the natural amino acids were chemically synthesized for the first time. A pool of these reagents was incorporated into oligonucleotides at substoichiometric levels to generate two libraries of variants that randomly carry either few or many codon replacements on a region encoding nine amino acids of the bacterial enzyme TEM-1 ?-lactamase. Assembly of the libraries was performed in a completely automated mode through a simple modification of ordinary protocols. This technology eliminates codon redundancy, stop codons and enables complete exploration of sequence space for single, double and triple mutations throughout a protein region spanning several residues. Sequence analysis of many non-selected clones revealed a good incorporation of the trinucleotides, producing combinations of mutations quite different from those obtained using conventional degenerate oligonucleotides. Ceftazidime-selection experiments yielded several never before reported variants containing novel amino acid combinations in the ?-lactamase omega loop region.

Yanez, Jorge; Arguello, Martha; Osuna, Joel; Soberon, Xavier; Gaytan, Paul

2004-01-01

229

Inhibited muscle amino acid uptake in sepsis.  

PubMed Central

Amino acid uptake in vivo was determined in soleus (SOL) muscle, diaphragm, heart, and liver following intravenous injection of [3H]-alpha-amino-isobutyric acid ([3H]-AIB) in rats made septic by cecal ligation and puncture (CLP) and in sham-operated controls. Muscle amino acid transport was also measured in vitro by determining uptake of [3H]-AIB in incubated extensor digitorum longus (EDL) and SOL muscles. Results were expressed as distribution ratio between [3H]-AIB in intracellular and extracellular fluid. AIB uptake in vivo was reduced by 90% in SOL and cardiac muscle and by 45% in diaphragm 16 hours after CLP. In contrast, AIB uptake by liver was almost four times higher in septic than in control animals. AIB uptake in vitro was reduced by 18% in EDL 8 hours after CLP but was not significantly altered in SOL at the same time point. Sixteen hours after CLP, AIB uptake was significantly reduced in both muscles, i.e., by 17% in EDL and by 65% in SOL. When muscles from untreated rats were incubated in the presence of plasma from septic animals (16 hours CLP) or from animals injected with endotoxin (2 mg/kg body weight), AIB uptake was reduced. Addition of endotoxin in vitro (2-200 micrograms/ml) to incubated muscles did not affect AIB uptake. The results suggest that sepsis leads to marked impairment of amino acid transport system A in muscle and that this impairment is mediated by a circulating factor that is not endotoxin. Reduced uptake of amino acids by skeletal muscle during sepsis may divert amino acids to the liver for increased gluconeogenesis and protein synthesis.

Hasselgren, P O; James, J H; Fischer, J E

1986-01-01

230

The Genetics of Heteromeric Amino Acid Transporters  

NSDL National Science Digital Library

Heteromeric amino acid transporters (HATs) are composed of a heavy (SLC3 family) and a light (SLC7 family) subunit. Mutations in system b0,+ (rBAT-b0,+AT) and in system y+L (4F2hc-y+LAT1) cause the primary inherited aminoacidurias (PIAs) cystinuria and lysinuric protein intolerance, respectively. Recent developments [including the identification of the first Hartnup disorder gene (B0AT1; SLC6A19)] and knockout mouse models have begun to reveal the basis of renal and intestinal reabsorption of amino acids in mammals.

Manuel Palacín (University of Barcelona Department of Biochemistry and Molecular Biology); Virginia Nunes (Institut de Recerca Oncològica Centre de Genètica Mèdica i Molecular); Mariona Font-Llitjós (Institut de Recerca Oncològica Centre de Genètica Mèdica i Molecular); Maite Jiménez-Vidal (University of Barcelona,Institut de Recerca Oncològica Department of Biochemistry and Molecular Biology,Centre de Genètica Mèdica i Molecular); Joana Fort (University of Barcelona Department of Biochemistry and Molecular Biology); Emma Gasol (University of Barcelona Department of Biochemistry and Molecular Biology)

2005-04-01

231

Papain-Assisted Resolution of Natural and Xenobiotic ?-Amino Acid  

Microsoft Academic Search

A new and convenient method for the preparation of pure enantiomers of ?-amino acids is described. Industrial papain, catalyzes the synthesis of L-Z-amino acid ethyl esters in ethanolic medium, with good yields. These esters are obtained from DL-Z-amino acids with 100% optical purity. Unreactive D-Z-amino acids are readily isolated from reaction medium. Physical constants of natural and xenobiotic L-Z-amino acid

J. L. Moriniere; B. Danree; J. Lemoine; A. Guy

1988-01-01

232

Apical Transporters for Neutral Amino Acids: Physiology and Pathophysiology  

NSDL National Science Digital Library

Absorption of amino acids in kidney and intestine involves a variety of transporters for different groups of amino acids. This is illustrated by inherited disorders of amino acid absorption, such as Hartnup disorder, cystinuria, iminoglycinuria, dicarboxylic aminoaciduria, and lysinuric protein intolerance, affecting separate groups of amino acids. Recent advances in the molecular identification of apical neutral amino acid transporters has shed a light on the molecular basis of Hartnup disorder and iminoglycinuria.

Stefan Broer (Australian National University)

2008-04-01

233

New Enzymatic Method of Chiral Amino Acid Synthesis by Dynamic Kinetic Resolution of Amino Acid Amides: Use of Stereoselective Amino Acid Amidases in the Presence of ?-Amino-?-Caprolactam Racemase?  

PubMed Central

d- and l-amino acids were produced from l- and d-amino acid amides by d-aminopeptidase from Ochrobactrum anthropi C1-38 and l-amino acid amidase from Pseudomonas azotoformans IAM 1603, respectively, in the presence of ?-amino-?-caprolactam racemase from Achromobacter obae as the catalyst by dynamic kinetic resolution of amino acid amides.

Yamaguchi, Shigenori; Komeda, Hidenobu; Asano, Yasuhisa

2007-01-01

234

Deduced amino acid sequence of human pulmonary surfactant proteolipid: SPL(pVal)  

SciTech Connect

Hydrophobic, proteolipid-like protein of Mr 6500 was isolated from ether/ethanol extracts of human, canine and bovine pulmonary surfactant. Amino acid composition of the protein demonstrated a remarkable abundance of hydrophobic residues, particularly valine and leucine. The N-terminal amino acid sequence of the human protein was determined: N-Leu-Ile-Pro-Cys-Cys-Pro-Val-Asn-Leu-Lys-Arg-Leu-Leu-Ile-Val4... An oligonucleotide probe was used to screen an adult human lung cDNA library and resulted in detection of cDNA clones with predicted amino acid sequence with close identity to the N-terminal amino acid sequence of the human peptide. SPL(pVal) was found within the reading frame of a larger peptide. SPL(pVal) results from proteolytic processing of a larger preprotein. Northern blot analysis detected in a single 1.0 kilobase SPL(pVal) RNA which was less abundant in fetal than in adult lung. Mixtures of purified canine and bovine SPL(pVal) and synthetic phospholipids display properties of rapid adsorption and surface tension lowering activity characteristic of surfactant. Human SPL(pVal) is a pulmonary surfactant proteolipid which may therefore be useful in combination with phospholipids and/or other surfactant proteins for the treatment of surfactant deficiency such as hyaline membrane disease in newborn infants.

Whitsett, J.A.; Glasser, S.W.; Korfhagen, T.R.; Weaver, T.E.; Clark, J.; Pilot-Matias, T.; Meuth, J.; Fox, J.L.

1987-05-01

235

The effect of fermentation and storage on free amino acids of tarhana.  

PubMed

A study on the evaluation of free amino acids (FAAs) in tarhana during fermentation and storage was performed. The FAAs in tarhana were determined by RP-HPLC with a fluorescence detector following extraction from the sample and derivatization with dansyl chloride. The amount of FAAs increased significantly (p<0.01) during fermentation and storage. The increase in the content of total free amino acids (TFAAs) and total free essential amino acids (TFEAAs) of fermented tarhana, which was used with yogurt bacteria and baker's yeast, was 57% and 93%, respectively. The amino acids primarily responsible for the increase were valine and tryptophan followed by methionine, alanine, isoleucine + leucine, phenylalanine, arginine, proline, and lysine. The TFAA content of tarhana at the end of fermentation was found to be 8% of total protein (16.8%). The ratio of TFEAAs/TFAAs was initially 0.46 and increased to 0.57 at the end of fermentation. The TFAA content of wet tarhanas was higher than that of the dry counterpart. It was found that the TFAA content of dry tarhana was 25% lower than the fresh wet tarhana (FWT), at the end of fermentation. It was concluded that the decrease in FAAs in dry tarhana was due to the Maillard reaction and partial degradation of FAAs during dehydration. PMID:16236596

Erbas, M; Ertugay, M F; Erbas, M O; Certel, M

2005-08-01

236

Effects of liver failure on the enzymes in the branched-chain amino acid catabolic pathway.  

PubMed

Branched-chain alpha-keto acid dehydrogenase (BCKDH) complex catalyzes the committed step of the catabolism of branched-chain amino acids (BCAA). The liver cirrhosis chemically induced in rats raised the activity of hepatic BCKDH complex and decreased plasma BCAA and branched-chain alpha-keto acid concentrations, suggesting that the BCAA requirement is increased in liver cirrhosis. Since the effects of liver cirrhosis on the BCKDH complex in human liver are different from those in rat liver, further studies are needed to clarify the differences between rats and humans. In the valine catabolic pathway, crotonase and beta-hydroxyisobutyryl-CoA hydrolase are very important to regulate the toxic concentration of mitochondrial methacrylyl-CoA, which occurs in the middle part of valine pathway and highly reacts with free thiol compounds. Both enzyme activities in human and rat livers are very high compared to that of BCKDH complex. It has been found that both enzyme activities in human livers were significantly reduced by liver cirrhosis and hepatocellular carcinoma, suggesting a decrease in the capability to dispose methacrylyl-CoA. The findings described here suggest that alterations in hepatic enzyme activities in the BCAA catabolism are associated with liver failure. PMID:14684172

Shimomura, Yoshiharu; Honda, Takashi; Goto, Hidemi; Nonami, Toshiaki; Kurokawa, Tsuyoshi; Nagasaki, Masaru; Murakami, Taro

2004-01-01

237

Branched-chain amino acid metabolism in rat muscle: abnormal regulation in acidosis  

SciTech Connect

Branched-chain amino acid (BCAA) metabolism is frequently abnormal in pathological conditions accompanied by chronic metabolic acidosis. To study how metabolic acidosis affects BCAA metabolism in muscle, rats were gavage fed a 14% protein diet with or without 4 mmol NH/sub 4/Cl x 100 g body wt/sup -1/ x day/sup -1/. Epitrochlearis muscles were incubated with L-(1-/sup 14/C)-valine and L-(1-/sup 14/C)leucine, and rates of decarboxylation, net transamination, and incorporation into muscle protein were measured. Plasma and muscle BCAA levels were lower in acidotic rats. Rates of valine and leucine decarboxylation and net transamination were higher in muscles from acidotic rats; these differences were associated with a 79% increase in the total activity of branched-chain ..cap alpha..-keto acid dehydrogenase and a 146% increase in the activated form of the enzyme. They conclude that acidosis affects the regulation of BCAA metabolism by enhancing flux through the transaminase and by directly stimulating oxidative catabolism through activation of branched-chain ..cap alpha..-keto acid dehydrogenase.

May, R.C.; Hara, Y.; Kelly, R.A.; Block, K.P.; Buse, M.G.; Mitch, W.E.

1987-06-01

238

Regional amino acid transport into brain during diabetes: Effect of plasma amino acids  

SciTech Connect

Transport of phenylalanine and lysine into the brain was measured in 4-wk streptozotocin-diabetic rats to assess the effect on the neutral and basic amino acid transport systems at the blood-brain barrier. Amino acid concentrations in plasma and brain were also measured. Regional permeability-times-surface area (PS) products and influx were determined using a continuous infusion method and quantitative autoradiography. The PS of phenylalanine was decreased by an average of 40% throughout the entire brain. Influx was depressed by 35%. The PS of lysine was increased by an average of 44%, but the influx was decreased by 27%. Several plasma neutral amino acids (branched chain) were increased, whereas all basic amino acids were decreased. Brain tryptophan, phenylalanine, tyrosine, methionine, and lysine contents were markedly decreased. The transport changes were almost entirely accounted for by the alterations in the concentrations of the plasma amino acids that compete for the neutral and basic amino acid carriers. The reduced influx could be responsible for the low brain content of some essential amino acids, with possibly deleterious consequences for brain functions.

Mans, A.M.; DeJoseph, M.R.; Davis D.W.; Hawkins, R.A. (Pennsylvania State Univ. College of Medicine, Hershey (USA))

1987-11-01

239

Asymmetric transfer hydrogenation of ketones catalyzed by amino acid derived rhodium complexes: on the origin of enantioselectivity and enantioswitchability.  

PubMed

Amino acid based thioamides, hydroxamic acids, and hydrazides have been evaluated as ligands in the rhodium-catalyzed asymmetric transfer hydrogenation of ketones in 2-propanol. Catalysts containing thioamide ligands derived from L-valine were found to selectively generate the product with an R configuration (95 % ee), whereas the corresponding L-valine-based hydroxamic acids or hydrazides facilitated the formation of the (S)-alcohols (97 and 91 % ee, respectively). The catalytic reduction was examined by performing a structure-activity correlation investigation with differently functionalized or substituted ligands and the results obtained indicate that the major difference between the thioamide and hydroxamic acid based catalysts is the coordination mode of the ligands. Kinetic experiments were performed and the rate constants for the reduction reactions were determined by using rhodium-arene catalysts derived from amino acid thioamide and hydroxamic acid ligands. The data obtained show that the thioamide-based catalyst systems demonstrate a pseudo-first-order dependence on the substrate, whereas pseudo-zero-order dependence was observed for the hydroxamic acid containing catalysts. Furthermore, the kinetic experiments revealed that the rate-limiting steps of the two catalytic systems differ. From the data obtained in the structure-activity correlation investigation and along with the kinetic investigation it was concluded that the enantioswitchable nature of the catalysts studied originates from different ligand coordination, which affects the rate-limiting step of the catalytic reduction reaction. PMID:19750526

Ahlford, Katrin; Ekström, Jesper; Zaitsev, Alexey B; Ryberg, Per; Eriksson, Lars; Adolfsson, Hans

2009-10-26

240

Evidence for valine intolerance in patients with cirrhosis.  

PubMed

Valine (62.5 mg per kg), leucine (70 mg per kg) and equal amounts of the calcium salts of the corresponding keto acids, i.e., alpha-ketoisovaleric acid (KIVA) and alpha-ketoisocaproic acid (KICA) were orally administered to patients with cirrhosis and to control subjects. Valine or leucine ingestion increased serum valine and leucine levels and the corresponding keto acids, KIVA and KICA, in cirrhotics and controls. KIVA or KICA ingestion increased serum KIVA and KICA concentrations within a few minutes associated with a rise in valine and leucine. In cirrhotics, administration of valine or KIVA resulted in significantly higher serum valine or KIVA concentrations than in control subjects. The clearance of valine and KIVA from blood was also delayed in cirrhotic patients. No such differences were observed after leucine or KICA ingestion. It is suggested that cirrhotics have a diminished tolerance for valine. Since the tolerance for KIVA, but not KICA, is also impaired, it appears that cirrhotics have a derangement in one or more metabolic steps distal to the branched-chain keto acid dehydrogenase. PMID:6745855

Schauder, P; Schröder, K; Herbertz, L; Langer, K; Langenbeck, U

241

Amino acids attached to transfer ribonucleic acid in vivo.  

PubMed Central

1. tRNA was extracted from rabbit liver by both the phenol and diethyl pyrocarbonate methods under conditions preventing deacylation of the amino acids attached in vivo. 2. After deacylation 12 amino acids were determined by gas-liquid chromatography, by using the flame-ionization and nitrogen-sensitive thermionic detectors. 3. Comparison of the distribution of 12 amino acids attached to tRNA with those contained in total tissue protein and in the free pool showed little correlation. 4. Results for the enzymic charging assay for tRNA in vitro did not correlate satisfactorily with the analysis of amino acids attached to tRNA in vivo. Marked differences were ntoed in comparison made between our own and other published results.

Butler, M; Darbre, A; Arnstein, H R

1975-01-01

242

Amino Acid Sequence of Human Cholinesterase.  

National Technical Information Service (NTIS)

The active site serine residue is located 198 amino acids from the N-terminal. The active site peptide was isolated from three different genetic types of human serum cholinesterase: from usual, atypical, and atypical-silent genotypes. It was found that th...

O. Lockridge

1985-01-01

243

The Exchangeability of Amino Acids in Proteins  

PubMed Central

The comparative analysis of protein sequences depends crucially on measures of amino acid similarity or distance. Many such measures exist, yet it is not known how well these measures reflect the operational exchangeability of amino acids in proteins, since most are derived by methods that confound a variety of effects, including effects of mutation. In pursuit of a pure measure of exchangeability, we present (1) a compilation of data on the effects of 9671 amino acid exchanges engineered and assayed in a set of 12 proteins; (2) a statistical procedure to combine results from diverse assays of exchange effects; (3) a matrix of “experimental exchangeability” values EXij derived from applying this procedure to the compiled data; and (4) a set of three tests designed to evaluate the power of an exchangeability measure to (i) predict the effects of amino acid exchanges in the laboratory, (ii) account for the disease-causing potential of missense mutations in the human population, and (iii) model the probability of fixation of missense mutations in evolution. EX not only captures useful information on exchangeability while remaining free of other effects, but also outperforms all measures tested except for the best-performing alignment scoring matrix, which is comparable in performance.

Yampolsky, Lev Y.; Stoltzfus, Arlin

2005-01-01

244

Dietary Supplements and Sports Performance: Amino Acids  

Microsoft Academic Search

This is the third in a series of six articles to discuss the major classes of dietary supplements (vitamins; minerals; amino acids; herbs or botanicals; metabolites, constituents\\/extracts, or combinations). The major focus is on efficacy of such dietary supplements to enhance exercise or sport performance.

Melvin Williams

2005-01-01

245

Amino acid modifications on tRNA  

PubMed Central

The accurate formation of cognate aminoacyl-tRNAs (aa-tRNAs) is essential for the fidelity of translation. Most amino acids are esterified onto their cognate tRNA isoacceptors directly by aminoacyl-tRNA synthetases (aaRSs). However, in the case of four amino acids (Gln, Asn, Cys and Sec), aminoacyl-tRNAs are made through indirect pathways in many organisms across all three domains of life. The process begins with the charging of noncognate amino acids to tRNAs by a specialized synthetase in the case of Cys-tRNACys formation or by synthetases with relaxed specificity such as the non-discriminating glutamyl-tRNA synthetase (ND-GluRS), non-discriminating aspartyl-tRNA synthetase (ND-AspRS) and seryl-tRNA synthetase (SerRS). The resulting misacylated tRNAs are then converted to cognate pairs through transformation of the amino acids on the tRNA, which is catalyzed by a group of tRNA-dependent modifying enzymes such as tRNA-dependent amidotransferases, Sep-tRNA:Cys-tRNA synthase (SepCysS), O-phosphoseryl-tRNA kinase (PSTK) and Sep-tRNA:Sec-tRNA synthase (SepSecS). The majority of these indirect pathways are widely spread in all domains of life and thought to be ancient in the course of evolution.

Yuan, Jing; Sheppard, Kelly; Soll, Dieter

2008-01-01

246

Optimization of short amino acid sequences classifier  

NASA Astrophysics Data System (ADS)

This article describes processing methods used for short amino acid sequences classification. The data processed are 9-symbols string representations of amino acid sequences, divided into 49 data sets - each one containing samples labeled as reacting or not with given enzyme. The goal of the classification is to determine for a single enzyme, whether an amino acid sequence would react with it or not. Each data set is processed separately. Feature selection is performed to reduce the number of dimensions for each data set. The method used for feature selection consists of two phases. During the first phase, significant positions are selected using Classification and Regression Trees. Afterwards, symbols appearing at the selected positions are substituted with numeric values of amino acid properties taken from the AAindex database. In the second phase the new set of features is reduced using a correlation-based ranking formula and Gram-Schmidt orthogonalization. Finally, the preprocessed data is used for training LS-SVM classifiers. SPDE, an evolutionary algorithm, is used to obtain optimal hyperparameters for the LS-SVM classifier, such as error penalty parameter C and kernel-specific hyperparameters. A simple score penalty is used to adapt the SPDE algorithm to the task of selecting classifiers with best performance measures values.

Barcz, Aleksy; Szyma?ski, Zbigniew

2012-05-01

247

Amino acid substitution matrices from protein blocks  

Microsoft Academic Search

Methods for alignment of protein sequences typically measure similarity by using a substitution matrix with scores for all possible exchanges of one amino acid with another. The most widely used matrices are based on the Dayhoff model of evolutionary rates. Using a different approach, we have derived substitution matrices from about 2000 blocks of aligned sequence segments characterizing more than

Steven Henikoff; Jorja G. Henikoff

1992-01-01

248

Protein tolerance to random amino acid change  

Microsoft Academic Search

Mutagenesis of protein-encoding sequences occurs ubiquitously; it enables evolution, accumulates during aging, and is associated with disease. Many biotechnological methods exploit random mutations to evolve novel proteins. To quantitate protein tolerance to random change, it is vital to understand the probability that a random amino acid replacement will lead to a protein's functional inactivation. We define this probability as the

Haiwei H. Guo; Juno Choe; Lawrence A. Loeb

2004-01-01

249

Dietary Supplements and Sports Performance: Amino Acids  

PubMed Central

This is the third in a series of six articles to discuss the major classes of dietary supplements (vitamins; minerals; amino acids; herbs or botanicals; metabolites, constituents/extracts, or combinations). The major focus is on efficacy of such dietary supplements to enhance exercise or sport performance.

Williams, Melvin

2005-01-01

250

Amino acid fermentation by Bacteroides melaninogenicus  

Microsoft Academic Search

Each of four strains ofBacteroides melaninogenicus grew well in a trypticaseyeast extract medium, without carbohydrate. Addition of glucose did not increase growth, and the sugar was fermented to only a limited extent. However, growth decreased when the trypticase concentration of the medium was reduced. These observations suggest that amino acid fermentation is of major importance in the energy metabolism ofB.

Ann Wahren; R. J. Gibbons

1970-01-01

251

Muscle amino acid pattern in obese rats  

Microsoft Academic Search

OBJECTIVE: To determine how the ability of skeletal muscle to manage amino acids is conditioned by obesity. The test was performed in two different models of obese rats: diet-obese rats and genetically obese rats. SUBJECTS: Lean and genetically obese (fa\\/fa) male Zucker rats were used. DESIGN: For up to 60 d of life lean animals were fed with standard chow

MC Herrero; X Remesar; C Bladé; LI Arola

1997-01-01

252

Amino Acid Metabolism of Pea Leaves  

PubMed Central

In the young leaves of pea (Pisum sativum L.) plants, there was a diurnal variation in the levels of amino acids. In the light, total amino nitrogen increased for the first few hours, then stabilized; in the dark, there was a transient decrease followed by a gradual recovery. Asparagine, homoserine, alanine, and glutamine accounted for much of these changes. The incorporation of 15N into various components of the young leaves was followed after supply of 15N-nitrate. 15N appeared most rapidly in ammonia, due to reduction in the leaf, and this process took place predominantly in the light. A large proportion of the primary assimilation took place through the amide group of glutamine, which became labeled and turned over rapidly; labeling of glutamic acid and alanine was also rapid. Asparagine (amide group) soon became labeled and showed considerable turnover. Slower incorporation and turnover were found for aspartic acid, ?-aminobutyric acid, and homoserine. Synthesis and turnover of all of the amino acids continued at a low rate in the dark. ?-Aminobutyric acid was the only compound found to label more rapidly in the dark than in the light.

Bauer, Alfred; Urquhart, Aileen A.; Joy, Kenneth W.

1977-01-01

253

L-Valine and L-Proline--solid-state IR-LD spectroscopic study.  

PubMed

Spectral investigation including IR-characteristic bands assignment of the amino acids zwitterions (L)-Valine ((L)-Val) and (L)-Proline ((L)-Pro) was carried out by linear-dichroic infrared (IR-LD) spectroscopy of oriented solid sample as a nematic liquid crystal suspension. The obtained experimental IR-LD results (transition moment directions) were compared with known crystal X-ray data for molecules orientation in the unit cells of the studied compounds, confirming the applicability of the used spectral method for structural determination. The influence of the protonation on the IR-spectroscopic patterns of the both amino acids is discussed. PMID:20236087

Chapkanov, A G; Zareva, S Y

2010-03-01

254

Metabolic effects of inhibitors of two enzymes of the branched-chain amino acid pathway in Salmonella typhimurium.  

PubMed Central

The metabolic effects of inhibitors of two enzymes in the pathway for biosynthesis of branched-chain amino acids were examined in Salmonella typhimurium mutant strain TV105, expressing a single isozyme of acetohydroxy acid synthase (AHAS), AHAS isozyme II. One inhibitor was the sulfonylurea herbicide sulfometuron methyl (SMM), which inhibits this isozyme and AHAS of other organisms, and the other was N-isopropyl oxalylhydroxamate (IpOHA), which inhibits ketol-acid reductoisomerase (KARI). The effects of the inhibitors on growth, levels of several enzymes of the pathway, and levels of intermediates of the pathway were measured. The intracellular concentration of the AHAS substrate 2-ketobutyrate increased on addition of SMM, but a lack of correlation between increased ketobutyrate and growth inhibition suggests that the former is not the immediate cause of the latter. The levels of the keto acid precursor of valine, but not of the precursor of isoleucine, were drastically decreased by SMM, and valine, but not isoleucine, partially overcame SMM inhibition. This apparent stronger effect of SMM on the flux into the valine arm, as opposed to the isoleucine arm, of the branched-chain amino acid pathway is explained by the kinetics of the AHAS reaction, as well as by the different roles of pyruvate, ketobutyrate, and the valine precursor in metabolism. The organization of the pathway thus potentiates the inhibitory effect of SMM. IpOHA has strong initial effects at lower concentrations than does SMM and leads to increases both in the acetohydroxy acid substrates of KARI and, surprisingly, in ketobutyrate. Valine completely protected strain TV105 from IpOHA at the MIC. A number of explanations for this effect can be ruled out, so that some unknown arrangement of the enzymes involved must be suggested. IpOHA led to initial cessation of growth, with partial recovery after a time whose duration increased with the inhibitor concentration. The recovery is apparently due to induction of new KARI synthesis, as well as disappearance of IpOHA from the medium.

Epelbaum, S; Chipman, D M; Barak, Z

1996-01-01

255

40 CFR 721.1705 - Benzoic acid, 3-amino-, diazotized, coupled with 6-amino-4-hydroxy-2-naphthalenesulfonic acid...  

Code of Federal Regulations, 2013 CFR

Benzoic acid, 3-amino-, diazotized, coupled with 6-amino-4-hydroxy-2-naphthalenesulfonic acid, diazotized, (3-aminophenyl)phosphonic acid and diazotized 2,5-diethoxybenzenamine. 721.1705 Section 721.1705 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY...

2013-07-01

256

Mammalian Amino Acid Transport System y + Revisited: Specificity and Cation Dependence of the Interaction with Neutral Amino Acids  

Microsoft Academic Search

.   A reevaluation of the specificity of system y+, the classical transporter for cationic amino acids is presented. System y+ has been defined as a transporter for cationic amino acids that binds neutral amino acids with lower affinity in the presence\\u000a of Na+. The discovery of other transporters for cationic amino has suggested that some properties, originally attributed to system

A. M. Rojas; R. Devés

1999-01-01

257

Photosynthetic Formation of the Aspartate Family of Amino Acids in Isolated Chloroplasts 1  

PubMed Central

The metabolism of 14C-labeled aspartic acid, diaminopimelic acid, malic acid and threonine by isolated pea (Pisum sativum L.) chloroplasts was examined. Light enhanced the incorporation of [14C] aspartic acid into soluble homoserine, isoleucine, lysine, methionine and threonine and protein-bound aspartic acid plus asparagine, isoleucine, lysine, and threonine. Lysine (2 millimolar) inhibited its own formation as well as that of homoserine, isoleucine and threonine. Threonine (2 millimolar) inhibited its own synthesis and that of homoserine but had only a small effect on isoleucine and lysine formation. Lysine and threonine (2 millimolar each) in combination strongly inhibited their own synthesis as well as that of homoserine. Radioactive [1,7-14C]diaminopimelic acid was readily converted into [14C]threonine in the light and its labeling was reduced by exogenous isoleucine (2 millimolar) or a combination of leucine and valine (2 millimolar each). The strong light stimulation of amino acid formation illustrates the point that photosynthetic energy is used in situ for amino acid and protein biosynthesis, not solely for CO2 fixation.

Mills, W. Ronald; Lea, Peter J.; Miflin, Benjamin J.

1980-01-01

258

Biological Properties of d-Amino Acid Conjugates of 2,4-D.  

PubMed

Some d-amino acid (glutamic acid, valine, or leucine) conjugates of 2,4-dichlorophenoxyacetic acid (2,4-D) at 10(-5) molar, stimulated elongation of Avena sativa L. var Mariner coleoptile sections and growth of soybean (Glycine max. L. var Amsoy) tissue as much as did the l-amino acid conjugates at 10(-6) molar. The d-methionine conjugate did not stimulate growth of soybean root callus tissue but did stimulate Avena elongation. The d-aspartic acid conjugate did not stimulate elongation of Avena coleoptiles but did stimulate growth of root callus tissue.Pretreatment of root callus tissue with 100 micromolar 2,4-D-(d) -or (l) glutamic acid for 18 hours prior to incubation for 6 hours in [1-(14)C]2,4-D resulted in a greater uptake of [1-(14)C]2,4-D than did pretreatment with 2,4-d. Qualitatively the metabolites were similar in all preincubation treatments. Preincubation with 2,4-D-(d)-glutamic acid also resulted in larger free [(14)C]2,4-D pool and a significant increase in water-soluble conjugates when compared with 2,4-D, or 2,4-D-(l)-glutamic acid preincubations. PMID:16662495

Davidonis, G H; Hamilton, R H; Vallejo, R P; Buly, R; Mumma, R O

1982-08-01

259

Sequential injection chromatography for fluorimetric determination of intracellular amino acids in marine microalgae.  

PubMed

This chapter describes a sequential injection chromatography method to automate the fluorimetric determination of amino acids after precolumn derivatization with o-phthaldialdehyde in presence of 2-mercaptoethanol using reverse-phase liquid chromatography in C(18) silica-based monolithic column. The method is low-priced and based on six steps of isocratic elutions. At a flow rate of 30 ?l/s, a 25 mm long-column coupled to 5-mm guard column is capable to separate aspartic acid (Asp), glutamic acid (Glu), asparagine (Asn), serine (Ser), glycine (Gly), threonine (Thr), citrulline (Ctr), arginine (Arg), alanine (Ala), tyrosine (Tyr), phenylalanine (Phe), ornithine (Orn), and lysine (Lys). Under these conditions, histidine (His) and glutamine (Gln), methionine (Met) and valine (Val), and isoleucine (Ile) and leucine (Leu) coelute. The entire cycle of amino acids derivatization, chromatographic separation, and column conditioning at the end of separation lasts 16 min. The method was successfully applied to the determination of the major intracellular free amino acids in the marine green alga Tetraselmis gracilis. PMID:22125154

Rigobello-Masini, Marilda; Masini, Jorge C

2012-01-01

260

Methods for assessing amino acid requirements and the effectiveness of a-keto acid analogs as substitutes for amino acids1' 2  

Microsoft Academic Search

Amino acid requirements of infants have been estimated by calculating amino acid intake from milk or formula diets of infants growing at a satisfactory rate. Amino acid requirements of adults have been estimated by determining the amount of each individual amino acid that must be included in a diet that is deficient in that amino acid in order to maintain

Alfred E. Harper

261

Amino acid regulation of TOR complex 1  

PubMed Central

TOR complex 1 (TORC1), an oligomer of the mTOR (mammalian target of rapamycin) protein kinase, its substrate binding subunit raptor, and the polypeptide Lst8/G?L, controls cell growth in all eukaryotes in response to nutrient availability and in metazoans to insulin and growth factors, energy status, and stress conditions. This review focuses on the biochemical mechanisms that regulate mTORC1 kinase activity, with special emphasis on mTORC1 regulation by amino acids. The dominant positive regulator of mTORC1 is the GTP-charged form of the ras-like GTPase Rheb. Insulin, growth factors, and a variety of cellular stressors regulate mTORC1 by controlling Rheb GTP charging through modulating the activity of the tuberous sclerosis complex, the Rheb GTPase activating protein. In contrast, amino acids, especially leucine, regulate mTORC1 by controlling the ability of Rheb-GTP to activate mTORC1. Rheb binds directly to mTOR, an interaction that appears to be essential for mTORC1 activation. In addition, Rheb-GTP stimulates phospholipase D1 to generate phosphatidic acid, a positive effector of mTORC1 activation, and binds to the mTOR inhibitor FKBP38, to displace it from mTOR. The contribution of Rheb's regulation of PL-D1 and FKBP38 to mTORC1 activation, relative to Rheb's direct binding to mTOR, remains to be fully defined. The rag GTPases, functioning as obligatory heterodimers, are also required for amino acid regulation of mTORC1. As with amino acid deficiency, however, the inhibitory effect of rag depletion on mTORC1 can be overcome by Rheb overexpression, whereas Rheb depletion obviates rag's ability to activate mTORC1. The rag heterodimer interacts directly with mTORC1 and may direct mTORC1 to the Rheb-containing vesicular compartment in response to amino acid sufficiency, enabling Rheb-GTP activation of mTORC1. The type III phosphatidylinositol kinase also participates in amino acid-dependent mTORC1 activation, although the site of action of its product, 3?OH-phosphatidylinositol, in this process is unclear.

Avruch, Joseph; Long, Xiaomeng; Ortiz-Vega, Sara; Rapley, Joseph; Papageorgiou, Angela; Dai, Ning

2009-01-01

262

Using pseudo amino acid composition to predict protein subcellular location: approached with amino acid composition distribution  

Microsoft Academic Search

Summary.  In the Post Genome Age, there is an urgent need to develop the reliable and effective computational methods to predict the\\u000a subcellular localization for the explosion of newly found proteins. Here, a novel method of pseudo amino acid (PseAA) composition,\\u000a the so-called “amino acid composition distribution” (AACD), is introduced. First, a protein sequence is divided equally into\\u000a multiple segments. Then,

J.-Y. Shi; S.-W. Zhang; Q. Pan; G.-P. Zhou

2008-01-01

263

Equilibrium absorption of carbon dioxide by amino acid salt and amine amino acid salt solutions  

Microsoft Academic Search

Experimental vapour liquid equilibrium (VLE) measurements were conducted for an amino acid salt(AAS), 3.5 M potassium sarcosinate and an amine amino acid salt (AAAS), the 5.0 M sarcosinate salt of 3-(methylamino)propylamine.The study was performed in two VLE apparatuses from 40 to 120 °C and for CO2 partial pressures ranging from 0.08 to 995 kPa. Thermodynamic models representing the AAS and AAAS solvent

Ugochukwu E. Aronu; Erik T. Hessen; Tore Haug-Warberg; Karl A. Hoff; Hallvard F. Svendsen

2011-01-01

264

Amino acid distribution of cereals in commerical mill products  

Microsoft Academic Search

Summary The amino acid contents of wheat and rice as well as their final products produced by commercial milling were determined quantitatively by the amino acid analyzer. Less quantities of lysine, glycine, arginine, alanine, and aspartic acid were found in the flour, whereas more levels of these amino acids were found in the wheat grain. Conversely, more proline, phenylalanine and

Hani M. El-Saied; M. A. Abdel-Moneim

1981-01-01

265

Reversed Phase Thin Layer Chromatography of Amino Acids  

Microsoft Academic Search

The use of reversed phase layers for the thin layer chromatography of amino acids is described. Only when a modifier was added to the mobile phase was clear separation of the amino acids achieved. Ion paring with trifluoroacetic acid overcame problems with streaking and poor separation on C2 or C18 reversed phase layers. All amino acids could not be separated

Joseph C. Touchstone; E. J. Levin; S. G. Lee

1984-01-01

266

Hypothalamic signaling in anorexia induced by indispensable amino acid deficiency.  

PubMed

Animals exhibit a rapid and sustained anorexia when fed a diet that is deficient in a single indispensable amino acid (IAA). The chemosensor for IAA deficiency resides within the anterior piriform cortex (APC). Although the cellular and molecular mechanisms by which the APC detects IAA deficiency are well established, the efferent neural pathways that reduce feeding in response to an IAA-deficient diet remain to be fully characterized. In the present work, we investigated whether 1) central melanocortin signaling is involved in IAA deficiency-induced anorexia (IAADA) and 2) IAADA engages other key appetite-regulating neuronal populations in the hypothalamus. Rats and mice that consumed a valine-deficient diet (VDD) for 2-3 wk exhibited marked reductions in food intake, body weight, fat and lean body mass, body temperature, and white adipose tissue leptin gene expression, as well as a paradoxical increase in brown adipose tissue uncoupling protein-1 mRNA. Animals consuming the VDD had altered hypothalamic gene expression, typical of starvation. Pharmacological and genetic blockade of central melanocortin signaling failed to increase long-term food intake in this model. Chronic IAA deficiency was associated with a marked upregulation of corticotropin-releasing hormone expression in the lateral hypothalamus, particularly in the parasubthalamic nucleus, an area heavily innervated by efferent projections from the APC. Our observations indicate that the hypothalamic melanocortin system plays a minor role in acute, but not chronic, IAADA and suggest that the restraint on feeding is analogous to that observed after chronic dehydration. PMID:23047987

Zhu, Xinxia; Krasnow, Stephanie M; Roth-Carter, Quinn R; Levasseur, Peter R; Braun, Theodore P; Grossberg, Aaron J; Marks, Daniel L

2012-10-09

267

Metabolomic analysis of amino acid metabolism in colitic rats supplemented with lactosucrose.  

PubMed

Intestinal inflammation causes metabolic disorders. The purpose of this study was to determine the effect of dietary supplementation with lactosucrose (LS) on the serum metabolome and intestinal luminal content of fatty acids in colitic rats. Colitis was induced in rats using trinitrobenzene sulfonic acid. Subsequently, rats received intragastric administration of either 250 mg LS/kg body weight or saline (the control group) every day for 5 weeks. Short-chain fatty acids in the intestinal lumen, blood profile, and metabolites in serum were measured, respectively, using gas chromatography, biochemistry analyzer, and nuclear magnetic resonance-based metabolomics combined with multivariate statistics. Metabolic effects of LS included: (1) decreases in concentrations of branched-chain amino acids (isoleucine and valine), alanine, citric acid, trimethylamine oxide and taurine, and the abundance of aspartate aminotransferase in serum; (2) increases in concentrations of glucose metabolites (including succinate) in serum; and (3) altered concentrations of butyrate in the cecal content and of butyrate and acetate in the colon content. The results indicate that LS supplementation to colitic rats affects whole-body metabolism of amino acids and release of aspartate aminotransferase and alkaline phosphatase from tissues into the blood circulation, and enhances the production of short-chain fatty acids in the intestinal lumen. PMID:23963536

Ruan, Zheng; Lv, Yinfei; Fu, Xiaofang; He, Qinghua; Deng, Zeyuan; Liu, Wenqun; Yingli, Yu; Wu, Xiaosong; Wu, Guoyao; Wu, Xin; Yin, Yulong

2013-08-21

268

Synthesis and characterization of new polyamides derived from alanine and valine derivatives  

PubMed Central

Background Many efforts have been recently devoted to design, investigate and synthesize biocompatible, biodegradable polymers for applications in medicine for either the fabrication of biodegradable devices or as drug delivery systems. Many of them consist of condensation of polymers having incorporated peptide linkages susceptible to enzymatic cleavage. Polyamides (PAs) containing ?-amino acid residues such as L-leucine, L-alanine and L-phenylalanine have been reported as biodegradable materials. Furthermore, polyamides (PAs) derived from C10 and C14 dicarboxylic acids and amide-diamines derived from 1,6-hexanediamine or 1,12-dodecanediamine and L-phenylalanine, L-valyl-L-phenylalanine or L-phenylalanyl-L-valine residues have been reported as biocompatible polymers. We have previously described the synthesis and thermal properties of a new type of polyamides-containing amino acids based on eight new symmetric meta-oriented protected diamines derived from coupling of amino acids namely; Fomc-glycine, Fmoc-alanine, Fomc-valine and Fomc-leucine with m-phenylene diamine or 2,6-diaminopyridine. Results revealed that incorporation of pyridine onto the polymeric backbone of all series decreases the thermal stability. Here we describe another family of polyamides based on benzene dicarboxylic acid, pyridine dicarboxylic acid, and ?-amino acid linked to benzidine and 4,4?-oxydianiline to study the effect of the dicarboxylic acid as well as the amino acids on the nature and thermal stability of the polymers. Results We report here the preparation of a new type of polyamides based on benzene dicarboxylic acid, pyridine dicarboxylic acid, and ?-amino acid linked to benzidine and 4,4?-oxydianiline to study the effect of the dicarboxylic acid as well as the amino acids on the nature and thermal stability of polymers. The thermal properties of the polymers were evaluated by different techniques. Results revealed that structure-thermal property correlation based on changing the dicarboxylic acid monomer or the diamine monomer demonstrated an interesting connection between a single change (changing the dicarboxylic acids in each series while the diamine is fixed) and thermal properties. The newly prepared polymers may possess biodegradability and thus may find some applications as novel biomaterials. Conclusions The thermal properties of the new type of polyamides based on benzene dicarboxylic acid, pyridine dicarboxylic acid, and ?-amino acid (alanine and valine) linked to benzidine and 4,4?-oxydianiline were evaluated by thermal gravimetric (TG), differential thermal gravimetric (DTG) and differential thermal analysis (DTA) techniques. Results revealed that the structure-thermal property correlation based on changing the dicarboxylic acid monomer or the diamine monomer demonstrated an interesting connection between a single change (changing the dicarboxylic acids in each series while the diamine is fixed) and thermal properties. In addition, pyridine-containing polymers exhibited semicrystalline characteristic with melting temperature, Tm. where none of the valine-containing polymers showed a melting and crystallization peak indicating that the polymers were amorphous. This is expected since L-valine side chain can inhibit close packing and eliminate crystallization. The newly prepared polymers may possess biodegradability and thus may find some applications as novel biomaterials.

2012-01-01

269

Creatinine Inhibits D-Amino Acid Oxidase  

Microsoft Academic Search

Inhibition of D-amino acid oxidase (DAO) activity by various uremic retention products and guanidino compounds was investigated. Creatinine (CTN) was found to inhibit DAO at a similar concentration in the sera of uremic patients. The inhibition was competitive and the Ki value was 2.7 mM. Moreover, CTN was shown to interact with flavin adenine dinucleotide (FAD), a coenzyme of DAO.

Y. Nohara; J. Suzuki; T. Kinoshita; M. Watanabe

2002-01-01

270

Amino acid imbalance and incomplete viral replication  

Microsoft Academic Search

Summary Four amino acids, lysine, leucine, tryptophane, and phenylalanine, at concentrations of 0.5 to 5.0 mg.\\/ml. inhibit the production of influenza viral hemagglutinins and complement-fixing S antigen in Krebs 2 ascites cells suspended in a medium containing only glucose and glutamate as substrates. In Krebs 2 cells no new infectious virus is formed but the hemagglutinins and CF antigen are

Monroe D. Eaton; Anthony R. Scala; Iolanda E. Low

1964-01-01

271

Secondary Transport of Amino Acids in Prokaryotes  

Microsoft Academic Search

Amino acid transport is a ubiquitous phenomenon and serves a variety of functions in prokaryotes, including supply of carbon\\u000a and nitrogen for catabolic and anabolic processes, pH homeostasis, osmoprotection, virulence, detoxification, signal transduction\\u000a and generation of electrochemical ion gradients. Many of the participating proteins have eukaryotic relatives and are successfully\\u000a used as model systems for exploration of transporter structure and

H. Jung; T. Pirch; D. Hilger

2006-01-01

272

Amino acids: metabolism, functions, and nutrition  

Microsoft Academic Search

Recent years have witnessed the discovery that amino acids (AA) are not only cell signaling molecules but are also regulators\\u000a of gene expression and the protein phosphorylation cascade. Additionally, AA are key precursors for syntheses of hormones\\u000a and low-molecular weight nitrogenous substances with each having enormous biological importance. Physiological concentrations\\u000a of AA and their metabolites (e.g., nitric oxide, polyamines, glutathione,

Guoyao Wu

2009-01-01

273

Alimentary proteins, amino acids and cholesterolemia  

Microsoft Academic Search

Numerous data from both epidemiological and experimental origins indicate that some alimentary proteins and amino acids in\\u000a supplements can modify the blood LDL cholesterol, HDL cholesterol and total cholesterol. After an initial approval of the\\u000a health claim for soy protein consumption for the prevention of coronary heart disease, more recently it has been concluded\\u000a from an overall analysis of literature

François Blachier; Antonio H. Lancha; Claire Boutry; Daniel Tomé

2010-01-01

274

Amino Acid Composition of Crystalline Botulinum Toxin, Type A.  

National Technical Information Service (NTIS)

The amino acid composition of botulinum toxin, type A, was determined with the aid of the automatic amino acid analyzer. The results are compared with an earlier largely microbiological analysis. (Author)

D. Stefanye

1965-01-01

275

Alimentary proteins, amino acids and cholesterolemia.  

PubMed

Numerous data from both epidemiological and experimental origins indicate that some alimentary proteins and amino acids in supplements can modify the blood LDL cholesterol, HDL cholesterol and total cholesterol. After an initial approval of the health claim for soy protein consumption for the prevention of coronary heart disease, more recently it has been concluded from an overall analysis of literature that isolated soy protein with isoflavones only slightly decrease LDL and total cholesterol. Other plant extracts and also some proteins from animal origin have been reported to exert a lowering effect on blood cholesterol when compared with a reference protein (often casein). The underlying mechanisms are still little understood. Individual amino acids and mixture of amino acids have also been tested (mostly in animal studies) for their effects on cholesterol parameters and on cholesterol metabolism. Methionine, lysine, cystine, leucine, aspartate and glutamate have been tested individually and in combination in different models of either normo or hypercholesterolemic animals and found to be able to modify blood cholesterol and/or LDL cholesterol and/or HDL cholesterol. It is however not known if these results are relevant to human nutrition. PMID:19184342

Blachier, François; Lancha, Antonio H; Boutry, Claire; Tomé, Daniel

2009-01-30

276

Thermodynamic study of solvation of some amino acids, diglycine and lysozyme in aqueous and mixed aqueous solutions  

Microsoft Academic Search

Apparent molar adiabatic compressibilities and viscosities of glycine, dl-?-alanine, dl-?-amino-n-butyric acid, l-valine, l-leucine and diglycine have been determined in aqueous and mixed aqueous solutions of mB=1.0, 2.0, 3.0, 4.0 and 5.0 aqueous n-propanol solutions at 298.15K. From these data the partial molar adiabatic compressibilities and viscosity B-coefficients have been evaluated to calculate the corresponding transfer functions. The partial molar adiabatic

Tarlok S. Banipal; Gagandeep Singh

2004-01-01

277

Transport and metabolism of amino acids in placenta  

Microsoft Academic Search

In all mammalian species, the 20 amino acids of the genetic code are required for net protein accretion. The nutritional supply\\u000a of amino acids for growth is defined as the net umbilical uptake of amino acids, representing the net transfer from maternal\\u000a circulation, through the placenta and then to the fetus, of essential and non-essential amino acids. In considering the

Timothy R. H. Regnault; Barbra de Vrijer; Frederick C. Battaglia

2002-01-01

278

Nutritional and medicinal aspects of d -amino acids  

Microsoft Academic Search

This paper reviews and interprets a method for determining the nutritional value of d-amino acids, d-peptides, and amino acid derivatives using a growth assay in mice fed a synthetic all-amino acid diet. A large number of\\u000a experiments were carried out in which a molar equivalent of the test compound replaced a nutritionally essential amino acid\\u000a such as l-lysine (l-Lys), l-methionine

Mendel FriedmanCarol; Carol E. Levin

279

Investigation of amine amino acid salts for carbon dioxide absorption  

Microsoft Academic Search

The carbon dioxide capture potential of amine amino acid salts (AAAS), formed by mixing equinormal amounts of amino acids; e.g. glycine, ?-alanine and sarcosine, with an organic base; 3-(methylamino)propylamine (MAPA), was assessed by comparison with monoethanolamine (MEA), and with amino acid salt (AAS) from amino acid neutralized with an inorganic base; potassium hydroxide (KOH). Carbon dioxide absorption and desorption experiments

Ugochukwu E. Aronu; Hallvard F. Svendsen; Karl Anders Hoff

2010-01-01

280

[Novel L-amino acid ligases catalyzing oligopeptide synthesis].  

PubMed

L-Amino acid ligase (EC 6.3.2.28) is a microbial enzyme catalyzing formation of an alpha-peptide bond from unprotected L-amino acids in an ATP-dependent manner. The YwfE protein from Bacillus subtilis 168 was the first reported L-amino acid ligase, and it synthesizes various dipeptides. Thereafter, several L-amino acid ligases were newly obtained by in silico analysis using the ATP-grasp motif. But these L-amino acid ligases synthesize only dipeptide and no longer peptide. A novel L-amino acid ligase capable of catalyzing oligopeptide synthesis is required to increase the variety of peptides. We have previously found a new member of L-amino acid ligase, RizA, from B. subtilis NBRC3134, a microorganism that produces the peptide-antibiotic rhizocticin. We newly found that a gene at approximately 9 kbp upstream of rizA encoded a novel L-amino acid ligase RizB. Recombinant RizB synthesized homo-oligomers of branched-chain amino acids consisting of 2 to 5 amino acids, and also synthesized various heteropeptides. RizB is the first reported L-amino acid ligase that catalyzes oligopeptide synthesis. In addition, we obtained L-amino acid ligases showing oligopeptide synthesis activities by in silico analysis using BLAST, which is a set of similarity search programs. These L-amino acid ligases showed low similarity in amino acid sequence, but commonly used branched-chain amino acids, such as RizB, as substrates. Furthermore, the spr0969 protein of Streptococcus pneumoniae synthesized longer peptides than those synthesized by RizB, and the BAD_1200 protein of Bifidobacteria adolescentis showed higher activity toward aromatic amino acids than toward branched-chain ones. PMID:21048404

Kino, Kuniki

2010-11-01

281

Amino acids interference on the quantification of reducing sugars by the 3,5-dinitrosalicylic acid assay mislead carbohydrase activity measurements.  

PubMed

This study evaluated the interference of the amino acids tryptophan, cysteine, histidine, tyrosine, hydroxyproline, leucine, proline, serine, glycine, valine, glutamic acid, phenylalanine, and methionine on the measurement of reducing sugars using a phenol-free 3,5-dinitrosalicylic acid (DNS) reagent. It was found that in reaction mixtures containing 20mM of either tryptophan, cysteine, histidine, tyrosine, or hydroxyproline the measurement of 3.7 mM glucose was overestimated by 76%, 50%, 35%, 18%, and 10%, respectively. The amino acids valine, glutamic acid, and phenylalanine did not affect the DNS reaction, while methionine decreased the color development by 5%. The measurement of glucose, xylose, arabinose, and cellobiose at the 3.7-12.4 mM range in the presence of 20 mM cysteine resulted in an overestimated concentration of 34.8-50%. Enzymatic assays for measuring xylanolytic and filter paper activity (FPAse) were conducted in the presence of 20-60 mM cysteine, and compared to cysteine-free assays. In the presence of cysteine, the measured xylanase activity increased threefold and the FPAse activity increased twofold due to the overestimation of the reducing sugar concentrations in the assays. The interference from cysteine was reduced to a maximum of 8.6% when a DNS reagent containing phenol was used. PMID:23103512

Teixeira, Ricardo Sposina Sobral; da Silva, Ayla Sant'Ana; Ferreira-Leitão, Viridiana Santana; da Silva Bon, Elba Pinto

2012-10-06

282

An amino acid at position 142 in nitrilase from Rhodococcus rhodochrous ATCC 33278 determines the substrate specificity for aliphatic and aromatic nitriles  

PubMed Central

Nitrilase from Rhodococcus rhodochrous ATCC 33278 hydrolyses both aliphatic and aromatic nitriles. Replacing Tyr-142 in the wild-type enzyme with the aromatic amino acid phenylalanine did not alter specificity for either substrate. However, the mutants containing non-polar aliphatic amino acids (alanine, valine and leucine) at position 142 were specific only for aromatic substrates such as benzonitrile, m-tolunitrile and 2-cyanopyridine, and not for aliphatic substrates. These results suggest that the hydrolysis of substrates probably involves the conjugated ?-electron system of the aromatic ring of substrate or Tyr-142 as an electron acceptor. Moreover, the mutants containing charged amino acids such as aspartate, glutamate, arginine and asparagine at position 142 displayed no activity towards any nitrile, possibly owing to the disruption of hydrophobic interactions with substrates. Thus aromaticity of substrate or amino acid at position 142 in R. rhodochrous nitrilase is required for enzyme activity.

Yeom, Soo-Jin; Kim, Hye-Jung; Lee, Jung-Kul; Kim, Dong-Eun; Oh, Deok-Kun

2008-01-01

283

Preparation of optically active ?-amino acids from microbial polyester polyhydroxyalkanoates  

Microsoft Academic Search

?-Amino acids, although less abundant than their ?-analogues, are also present in peptides and other natural products, and in their free forms and derivatives show interest- ing pharmacological effects. A number of methods for synthesis and transformations leading to ?-amino acids in diastereomerically and enantiomerically enriched forms have been reported.1 The synthesis of modified peptides containing ?-amino acids as key

Sang Hyun Park; Seung Hwan Lee; Sang Yup Lee

2001-01-01

284

A partial amino acid sequence for sheep haemoglobin A  

PubMed Central

Amino acid analysis and terminal-group analysis of tryptic and chymotryptic peptides from sheep haemoglobin A have enabled a partial amino acid sequence to be worked out. By comparing this partial sequence with the known amino acid sequences of human haemoglobins A and F as well as horse slow haemoglobin the most probable sequence of sheep haemoglobin has been deduced.

Beale, D.

1967-01-01

285

New insights into amino acid metabolism, ?-cell function and diabetes  

Microsoft Academic Search

Specific amino acids are now known to acutely and chronically regulate insulin secretion from pancreatic ?-cellsinvivo andinvitro. Understanding the molecular mechanisms by which amino acids regulate insulin secretion may identify novel targets for future diabetes therapies. Mitochondrial metabolism is crucial for the coupling of amino acid and glucose recognition to the exocytosis of the insulin granules. This is illustrated by

Philip NEWSHOLME; Lorraine BRENNAN; Blanca RUBI; Pierre MAECHLER

2005-01-01

286

Genetic Engineering of Amino Acid Metabolism in Plants  

Microsoft Academic Search

Amino acids are not only building blocks of proteins but also participate in many metabolic networks that control growth and adaptation to the environment. In young plants, amino acid biosynthesis is regulated by a compound metabolic network that links nitrogen assimilation with carbon metabolism. This network is strongly regulated by the metabolism of four central amino acids, namely glutamine, glutamate,

Shmuel Galili; Rachel Amir; Gad Galili

2008-01-01

287

Protein and amino acid nutrition of lactating dairy cattle.  

PubMed

This article describes the National Research Council Model of protein metabolism and illustrates its use in meeting the protein requirements of lactating cows. Attention is then directed toward amino acid nutrition with emphasis on the need for models to estimate amino acid requirements. Finally, the potential to improve productivity with rumen-protected amino acids is considered. PMID:1893276

Chalupa, W; Sniffen, C J

1991-07-01

288

Soil amino acid composition across a boreal forest successional sequence  

Microsoft Academic Search

Soil amino acids are important sources of organic nitrogen for plant nutrition, yet few studies have examined which amino acids are most prevalent in the soil. In this study, we examined the composition, concentration, and seasonal patterns of soil amino acids across a primary successional sequence encompassing a natural gradient of plant productivity and soil physicochemical characteristics. Soil was collected

Nancy R. Werdin-Pfisterer; Knut Kielland; Richard D. Boone

2009-01-01

289

Amino acid biogeo- and stereochemistry in coastal Chilean sediments  

Microsoft Academic Search

The spatial distribution of total hydrolysable amino acids (THAA) and amino acid enantiomers (D- and L-forms) was investigated in sediments underlying two contrasting Chilean upwelling regions: at ? 23 ? S off Antofagasta and at ? 36 ? S off Concepcion. The contri- bution of amino acids to total organic carbon (%TAAC: 7-14%) and total nitrogen (%TAAN: 23-38%) in surface

Bente Aa; Bo B. Jørgensen; Carsten J. Schubert; Jutta Niggemann

2006-01-01

290

Amino Acid Pair Interchanges at Spatially Conserved Locations  

Microsoft Academic Search

Here we study the pattern of amino acid pair interchanges at spatially, locally conserved regions in globally dissimilar and unrelated proteins. By using a method which completely separates the amino acid sequence from its respective structure, this work addresses the question of which properties of the amino acids are the most crucial for the stability of conserved structural motifs. The

Dalit Naor; Daniel Fischer; Robert L. Jernigan; Haim J. Wolfson; Ruth Nussinov

1996-01-01

291

Awake craniotomy induces fewer changes in the plasma amino acid profile than craniotomy under general anesthesia.  

PubMed

In this prospective, observational, 2-armed study, we compared the plasma amino acid profiles of patients undergoing awake craniotomy to those undergoing craniotomy under general anesthesia. Both experimental groups were also compared with a healthy, age-matched and sex-matched reference group not undergoing surgery. It is our intention to investigate whether plasma amino acid levels provide information about physical and emotional stress, as well as pain during awake craniotomy versus craniotomy under general anesthesia. Both experimental groups received preoperative, perioperative, and postoperative dexamethasone. The plasma levels of 20 amino acids were determined preoperative, perioperative, and postoperatively in all groups and were correlated with subjective markers for pain, stress, and anxiety. In both craniotomy groups, preoperative levels of tryptophan and valine were significantly decreased whereas glutamate, alanine, and arginine were significantly increased relative to the reference group. Throughout time, tryptophan levels were significantly lower in the general anesthesia group versus the awake craniotomy group. The general anesthesia group had a significantly higher phenylalanine/tyrosine ratio, which may suggest higher oxidative stress, than the awake group throughout time. Between experimental groups, a significant increase in large neutral amino acids was found postoperatively in awake craniotomy patients, pain was also less and recovery was faster. A significant difference in mean hospitalization time was also found, with awake craniotomy patients leaving after 4.53+/-2.12 days and general anesthesia patients after 6.17+/-1.62 days; P=0.012. This study demonstrates that awake craniotomy is likely to be physically and emotionally less stressful than general anesthesia and that amino acid profiling holds promise for monitoring postoperative pain and recovery. PMID:19295387

Hol, Jaap W; Klimek, Markus; van der Heide-Mulder, Marieke; Stronks, Dirk; Vincent, Arnoud J; Klein, Jan; Zijlstra, Freek J; Fekkes, Durk

2009-04-01

292

Regulation of Branched-Chain Amino Acid Biosynthesis in Salmonella typhimurium: Isolation of Regulatory Mutants  

PubMed Central

5?,5?,5?-Trifluoro-dl-leucine inhibited the activity of ?-isopropylmalate synthetase (the initial enzyme unique to leucine biosynthesis) as well as the growth of Salmonella typhimurium. Mutants of S. typhimurium resistant to the analogue were isolated and characterized. In most cases, they overproduced and excreted leucine or leucine, valine, and isoleucine as a result of an alteration in the regulation of branched-chain amino acid biosynthesis. Biochemical and genetic tests allowed the mutants to be grouped into three classes: I, a moderately large group (13%) which had high, constitutive leucine biosynthetic enzyme levels and mutant sites linked to the leucine operon (operator constitutive); II, a single mutant in which the mutant site was linked to the leucine operon and in which ?-isopropylmalate synthetase was not inhibited by leucine (feedback negative); III, a majority type which had constitutive levels of leucine, valine, and isoleucine biosynthetic enzymes and mutant sites unlinked to the leucine operon. Mutants of class I provide important evidence for the concept of an operon organization of genes involved in leucine biosynthesis. The properties of class III mutants indicate that there is some element involved in regulation which is common to the three pathways. Images

Calvo, J. M.; Freundlich, M.; Umbarger, H. E.

1969-01-01

293

Alpha-helix stabilization by natural and unnatural amino acids with alkyl side chains.  

PubMed Central

Knowledge of the role of individual side chains in forming different secondary structures such as the alpha-helix would be useful for prediction of protein structure from sequence or de novo protein design. Experimental and theoretical studies on natural and synthetic peptides and proteins indicate that individual side chains differ in their helix-forming potential. Four aliphatic side chains occur in the standard complement of amino acids: alanine and leucine are helix stabilizing, whereas isoleucine and valine are weakly destabilizing. We have synthesized a series of helical peptides containing unnatural aliphatic side chains having two to four carbons to explore some of the factors involved in alpha-helix stabilization and the basis for selection of the natural set. We find that linear side chains with two, three, or four carbons are as strongly helix stabilizing as the single methyl in alanine and that all linear side chains are stronger helix promoters than leucine. In addition, a t-butyl side chain is significantly more helix destabilizing than the sec-butyl side chain of isoleucine, the isopropyl side chain of valine, or even the unrestricted side chain of glycine. These results provide experimental evidence that restriction in conformational freedom of a side chain imposed by alpha-helix formation is a major component of the role of a side chain in stabilizing helical structure.

Lyu, P C; Sherman, J C; Chen, A; Kallenbach, N R

1991-01-01

294

Biosynthesis of branched-chain amino acids is essential for effective symbioses between betarhizobia and Mimosa pudica.  

PubMed

Burkholderia phymatum STM815 and Cupriavidus taiwanensis LMG19424 are betaproteobacterial strains that can effectively nodulate several species of the large legume genus Mimosa. A Tn5 mutant, derived from B. phymatum STM815 (KM60), and another derived from C. taiwanensis LMG19424 (KM184-55) induced Fix(-) nodules on Mimosa pudica. The Tn5-interrupted genes of the mutants showed strong homologies to ilvE, which encodes a branched-chain amino acid aminotransferase, and leuC, which encodes the large subunit of isopropylmalate isomerase. Both enzymes are known to be involved in the biosynthetic pathways for branched-chain amino acids (BCAAs) (leucine, valine and isoleucine). The B. phymatum ilvE mutant, KM60, was not auxotrophic for BCAAs and could grow well on minimal medium with pyruvate as a carbon source and ammonia as a nitrogen source. However, it grew less efficiently than the wild-type (WT) strain when ammonia was substituted with valine or isoleucine as a nitrogen source. The BCAA aminotransferase activity of KM60 was significantly reduced relative to the WT strain, especially with isoleucine and valine as amino group donors. The C. taiwanensis leuC mutant, KM184-55, could not grow on a minimal medium with pyruvate as a carbon source and ammonia as a nitrogen source, but its growth was restored when leucine was added to the medium. The isopropylmalate isomerase activity of KM184-55 was completely lost compared with the WT strain. Both mutants recovered their respective enzyme activities after complementation with the WT ilvE or leuC genes and were subsequently able to grow as well as their parental strains on minimal medium. They were also able to form nitrogen-fixing nodules on M. pudica. We conclude that the biosynthesis of BCAAs is essential for the free-living growth of betarhizobia, as well as for their ability to form effective symbioses with their host plant. PMID:22556357

Chen, Wen-Ming; Prell, Jurgen; James, Euan K; Sheu, Der-Shyan; Sheu, Shih-Yi

2012-05-03

295

Partitioning behavior of amino acids in aqueous two-phase systems formed by imidazolium ionic liquid and dipotassium hydrogen phosphate.  

PubMed

Partition coefficients of amino acids, including glycine, alanine, 2-aminobutyric acid, valine, leucine, threonine, methinoine, tryptophan and tyrosine, in [C(n)mim]Br (n=4, 6, 8)+K(2)HPO(4) aqueous two-phase systems (ATPSs) have been determined, and the relative hydrophobicity of the equilibrium phases in the ionic liquids-based aqueous two-phase systems has been characterized by the Gibbs energies of transfer for methylene group from the bottom salt-rich phase to the top ionic liquid-rich phase. Based on these results, factors affecting the partitioning behavior of the amino acids have been investigated. It is shown that partition coefficients of the amino acids increase with the increase of hydrophobicity of the amino acids and the ionic liquids, solution pH value, tie-line length of the ATPSs and temperature of the systems. The possible driving forces and the thermodynamic parameters for the partitioning of amino acids in the ionic liquids-based ATPSs have also been discussed. PMID:22364668

Pei, Yuanchao; Li, Zhiyong; Liu, Li; Wang, Jianji

2012-02-08

296

Production of d-amino acids by N-acyl- d-amino acid amidohydrolase and its structure and function  

Microsoft Academic Search

d-Amino acids have been widely used as synthetic materials for various compounds such as pharmaceuticals and agrochemicals. The manufacture of d-amino acids by fermentation is difficult, and enzymatic methods are mainly employed. At present, the optical resolution method using N-acyl-d-amino acid amidohydrolase is the most useful and convenient. In this review, the application of N-acyl-d-amino acid amidohydrolase to the production

Mamoru Wakayama; Kazuaki Yoshimune; Yoshihiko Hirose; Mitsuaki Moriguchi

2003-01-01

297

Regulation of taste-active components of meat by dietary branched-chain amino acids; effects of branched-chain amino acid antagonism.  

PubMed

1. The effects of dietary branched-chain amino acids (BCAAs) including leucine (Leu), isoleucine (Ile) and valine (Val) on taste-active components, especially free glutamate (Glu), in meat were investigated. 2. Broiler chickens (28 d old) were given varied dietary BCAA levels for 10 d before marketing. Dietary BCAA content ratios were either 100:100:100 (Low Leu group), 150:100:100 (Control group) or 150:150:150 (High Ile + Val group) for Leu:Ile:Val (% of each BCAA requirement according to NRC, 1994). Taste-related components of meat (free amino acids and ATP metabolites) and sensory scores of meat soup were estimated. 3. Free Glu content, the main taste-active component of meat, was significantly increased by dietary BCAA. Compared to the Control group, free Glu content increased by 30% in the High Ile + Val group. However, the inosine monophosphate (IMP) content in meat did not change among groups. 4. Sensory evaluation of meat soups showed that Control and High Ile + Val groups had different meat flavours. The sensory score of overall taste intensity was significantly higher in the High Ile + Val group. 5. These results suggest that dietary BCAA concentrations regulate free Glu in meat. Increasing dietary Ile + Val induces an increase in free Glu content of meat, improves meat taste and is more effective for increasing free Glu content in meat than decreasing dietary Leu level. PMID:18568754

Imanari, M; Kadowaki, M; Fujimura, S

2008-05-01

298

Essential branched-chain amino acids and alpha-ketoanalogues in haemodialysis patients.  

PubMed

Homeostasis of essential amino acids and their transamination derivatives (ketoacids) is disturbed in haemodialysis (HD) patients. In long-term HD patients a hypercatabolic state is often paired with severe anaemia. To understand metabolic regulation mechanisms we measured with an improved fluorescence-HPLC method plasma concentrations of valine (Val), isoleucine (Ile), and leucine (Leu) and their corresponding ketoacids ketoisovaleric acid (KIV), ketomethylvaleric acid (KMV), and ketoisocaproic acid (KIC). The values of 18 modestly anaemic HD patients (group A: Hb greater than 11 g/dl) and of 16 severely anaemic HD patients (group B: Hb less than 8 g/dl) were compared with 19 healthy control persons (100%; significance of patient values vs controls P less than 0.05) and with each other (significantly different at P less than 0.05). Both branched chain amino acids and ketoacids are diminished in HD patients. This disturbance of protein metabolism is intensified with severe anaemia. The decrease of transamination products KIV and KMV parallels that of their corresponding Val and Ile, whereas KIC is reduced out of proportion to Leu. Leu has anabolic function and KIC antiproteolytic effects. Decreased Leu and KIC indicate catabolism. Reduced transamination of Leu and KIC suggests an endogenous protective mechanism against catabolism independent of anaemia. These differences should be considered with supplementation therapy of branched-chain compounds in HD patients. PMID:1314969

Riedel, E; Hampl, H; Nündel, M; Farshidfar, G

1992-01-01

299

Studies in the polarography of metal-amino acid complexes  

Microsoft Academic Search

Summary  1. The polarographic behaviour of glycine,?-alanine,?-alanine, valine, aspartic acid, glutamic acid and asparagine complexes of lead has been studied at various pH values and\\u000a in presence of (1) NaOH, (2) Na2CO3 and (3) NH4 NO3+NH4OH. All the polarographic waves have been found to be reversible.\\u000a \\u000a 2. Experiments conducted on the effect of variation of pH,i.e., 7

G. Nageswara Rao; R. S. Subrahmanya

1964-01-01

300

Dietary and endogenous amino acids are the main contributors to microbial protein in the upper gut of normally nourished pigs.  

PubMed

Although amino acids (AA) synthesized by enteric microbiota in the upper gut of nonruminants can be absorbed, they do not necessarily make a net contribution to the host's AA supply. That depends on whether protein or nonprotein nitrogen sources are used for microbial protein production. We determined the contributions of urea, endogenous protein (EP), and dietary protein (DP) to microbial valine (M.VAL) at the distal ileum of growing pigs, based on isotope dilutions after a 4-d continuous infusion of l-[1-(13)C]valine to label EP and of [(15)N(15)N]urea. Eight barrows were assigned to either a cornstarch and soybean meal-based diet with or without 12% added fermentable fiber from pectin. Dietary pectin did not affect (P > 0.10) the contributions of the endogenous and DP to M.VAL. More than 92% of valine in microbial protein in the upper gut was derived from preformed AA from endogenous and DP, suggesting that de novo synthesis makes only a small contribution to microbial AA. PMID:19403708

Libao-Mercado, Aileen Joy O; Zhu, Cuilan L; Cant, John P; Lapierre, Hélène; Thibault, Jean-Noël; Sève, Bernard; Fuller, Malcolm F; de Lange, Cornelis F M

2009-04-29

301

?-Transaminase-catalyzed asymmetric synthesis of unnatural amino acids using isopropylamine as an amino donor.  

PubMed

Isopropylamine is an ideal amino donor for reductive amination of carbonyl compounds by ?-transaminase (?-TA) owing to its cheapness and high volatility of a ketone product. Here we developed asymmetric synthesis of unnatural amino acids via ?-TA-catalyzed amino group transfer between ?-keto acids and isopropylamine. PMID:23897436

Park, Eul-Soo; Dong, Joo-Young; Shin, Jong-Shik

2013-09-25

302

Plasma Amino Acids and Stomach Contents oí Rats Fed Casein and the Corresponding Amino Acid Mixture  

Microsoft Academic Search

This study with rats was conducted to make clear the cause of lower intake of the diet containing the amino acid mixture simulating casein in place of intact casein in ad libitum feeding experiments. Comparing with the rats force-fed casein diet, those force-fed amino acid diet showed higher essential amino acid concen trations in plasma at 1 and 2 hours

HIROSHI ITOH

2010-01-01

303

Extracellular Amino Acid Effects on Milk Protein Synthesis and Intracellular Amino Acid Pools with Bovine Mammary Cells in Culture 1  

Microsoft Academic Search

Increases in free intracellular amino acids are associated with increased protein synthesis. Responses in synthesis of 18-casein and t3qactoglobulin and of intracellular amino acid pools to graded concentrations of amino acids in the medium were observed. Mammary tissue from two Holstein cows was dispersed and cultured for 18 h with Eagle's mini- mal essential medium containing 1, 3, 5, or

R. M. CLARK; P. T. CHANDLER; A. W. NORMAN

304

Some of the amino acid chemistry going on in the Laboratory of Amino Acids, Peptides and Proteins  

Microsoft Academic Search

Summary Some of the chemistry of amino acids going on in our laboratory (Laboratoire des Amino acides Peptides et Protéines) is described as well as some mass spectrometry methodology for their characterization particularly on solid supports. Several aspects are presented including: (i) the stereoselective synthesis of natural and unnatural amino acids using 2-hydroxypinan-3-one as chiral auxiliary; (ii) the stereoselective synthesis

S. Bouifraden; C. Drouot; M. El Hadrami; F. Guenoun; L. Lecointe; N. Mai; C. Pothion; M. Sadoune; B. Sauvagnat; M. Amblard; J. L. Aubagnac; M. Calmes; P. Chevallet; J. Daunis; C. Enjalbal; J. A. Fehrentz; F. Lamaty; J. P. Lavergne; R. Lazaro; V. Rolland; M. L. Roumestant; Ph. Viallefont; Y. Vidal; J. Martinez

1999-01-01

305

Ileal losses of nitrogen and amino acids in humans and their importance to the assessment of amino acid requirements  

Microsoft Academic Search

Background & Aims: Irreversible amino acid losses at the human ileum are not taken into account when tracer-derived amino acid requirements are calculated because the data available are scarce. We have investigated amino acid losses at the ileal level in humans after ingestion of a protein meal. Methods: Thirteen volunteers ingested a single meal of 15N milk or soy proteins.

Claire Gaudichon; Cécile Bos; Céline Morens; Klaus J. Petzke; François Mariotti; Julia Everwand; Robert Benamouzig; Sophie Daré; Daniel Tomé; Cornelia C. Metges

2002-01-01

306

An examination of the carbon isotope effects associated with amino acid biosynthesis.  

PubMed

Stable carbon isotope ratios (delta(13)C) were determined for alanine, proline, phenylalanine, valine, leucine, isoleucine, aspartate (aspartic acid and asparagine), glutamate (glutamic acid and glutamine), lysine, serine, glycine, and threonine from metabolically diverse microorganisms. The microorganisms examined included fermenting bacteria, organotrophic, chemolithotrophic, phototrophic, methylotrophic, methanogenic, acetogenic, acetotrophic, and naturally occurring cryptoendolithic communities from the Dry Valleys of Antarctica. Here we demonstrated that reactions involved in amino acid biosynthesis can be used to distinguish amino acids formed by life from those formed by nonbiological processes. The unique patterns of delta(13)C imprinted by life on amino acids produced a biological bias. We also showed that, by applying discriminant function analysis to the delta(13)C value of a pool of amino acids formed by biological activity, it was possible to identify key aspects of intermediary carbon metabolism in the microbial world. In fact, microorganisms examined in this study could be placed within one of three metabolic groups: (1) heterotrophs that grow by oxidizing compounds containing three or more carbon-to-carbon bonds (fermenters and organotrophs), (2) autotrophs that grow by taking up carbon dioxide (chemolitotrophs and phototrophs), and (3) acetoclastic microbes that grow by assimilation of formaldehyde or acetate (methylotrophs, methanogens, acetogens, and acetotrophs). Furthermore, we demonstrated that cryptoendolithic communities from Antarctica grouped most closely with the autotrophs, which indicates that the dominant metabolic pathways in these communities are likely those utilized for CO(2 )fixation. We propose that this technique can be used to determine the dominant metabolic types in a community and reveal the overall flow of carbon in a complex ecosystem. PMID:17155886

Scott, James H; O'Brien, Diane M; Emerson, David; Sun, Henry; McDonald, Gene D; Salgado, Antonio; Fogel, Marilyn L

2006-12-01

307

An Examination of the Carbon Isotope Effects Associated with Amino Acid Biosynthesis  

NASA Astrophysics Data System (ADS)

Stable carbon isotope ratios (?13C) were determined for alanine, proline, phenylalanine, valine, leucine, isoleucine, aspartate (aspartic acid and asparagine), glutamate (glutamic acid and glutamine), lysine, serine, glycine, and threonine from metabolically diverse microorganisms. The microorganisms examined included fermenting bacteria, organotrophic, chemolithotrophic, phototrophic, methylotrophic, methanogenic, acetogenic, acetotrophic, and naturally occurring cryptoendolithic communities from the Dry Valleys of Antarctica. Here we demonstrated that reactions involved in amino acid biosynthesis can be used to distinguish amino acids formed by life from those formed by nonbiological processes. The unique patterns of ?13C imprinted by life on amino acids produced a biological bias. We also showed that, by applying discriminant function analysis to the ?13C value of a pool of amino acids formed by biological activity, it was possible to identify key aspects of intermediary carbon metabolism in the microbial world. In fact, microorganisms examined in this study could be placed within one of three metabolic groups: (1) heterotrophs that grow by oxidizing compounds containing three or more carbon-to-carbon bonds (fermenters and organotrophs), (2) autotrophs that grow by taking up carbon dioxide (chemolitotrophs and phototrophs), and (3) acetoclastic microbes that grow by assimilation of formaldehyde or acetate (methylotrophs, methanogens, acetogens, and acetotrophs). Furthermore, we demonstrated that cryptoendolithic communities from Antarctica grouped most closely with the autotrophs, which indicates that the dominant metabolic pathways in these communities are likely those utilized for CO2 fixation. We propose that this technique can be used to determine the dominant metabolic types in a community and reveal the overall flow of carbon in a complex ecosystem.

Scott, James H.; O'Brien, Diane M.; Emerson, David; Sun, Henry; McDonald, Gene D.; Salgado, Antonio; Fogel, Marilyn L.

2006-12-01

308

“Facilitated” Amino Acid Transport Is Upregulated in Brain Tumors  

Microsoft Academic Search

The goal of this study was to determine the magnitude of“facilitated” amino acid transport across tumor and brain capillaries and to evaluate whether amino acid transporter expression is“upregulated” in tumor vessels compared to capillaries in contralateral brain tissue. Aminocyclopentane carboxylic acid (ACPC), a non-metabolized [14C]-labeled amino acid, and a reference molecule for passive vascular permeability,[67Ga]-gallium-diethylenetriaminepentaacetic acid (Ga-DTPA), were used in

Tadashi Miyagawa; Takamitsu Oku; Hisao Uehara; Revathi Desai; Bradley Beattie; Juri Tjuvajev; Ronald Blasberg

1998-01-01

309

Structure-function relationships of heterodimeric amino acid transporters  

Microsoft Academic Search

Heterodimeric amino acid transporters mediate the transfer of amino acids between organs and between different cell types.\\u000a Members of this particular family of amino acid transporters are constituted by a heavy chain and an associated light chain.\\u000a The heavy chain is a type II membrane protein with an intracellular amino terminus, a single transmembrane helix, and a large\\u000a extracellular domain.

Stefan Bröer; Carsten A. Wagner

2002-01-01

310

Hemoglobin Olympia (?20 Valine -> Methionine): An Electrophoretically Silent Variant Associated with High Oxygen Affinity and Erythrocytosis  

PubMed Central

In a family with erythrocytosis, electrophoretic and chromatographic studies failed to demonstrate a hemoglobin variant. However, the oxygen dissociation curves of affected individuals were shifted to the left of normal and this shift persisted when oxygen equilibria were studied in 2.3-diphosphoglycerate-stripped hemolysates. A mutant hemoglobin was evidently present in the red blood cells of the affected persons and was responsible for the increased oxygen affinity and erythrocytosis. Specific staining of tryptic peptide maps of ?-chains from the propositus showed that peptide ?T3 was positive for a sulfur-containing amino acid. Amino acid analysis yielded a composition identical to that of normal ?T3, except that there were 2.6 residues of valine and 0.4 residues of methionine (normal composition: Val = 3.0, Met = 0). This suggested that the ?-chains of affected individuals consisted of a mixture of two kinds of chains, 40% of which had a methionyl residue in ?T3. Structural studies of isolated cyanogen bromide fragments demonstrated unequivocally that, in the abnormal ?-chains, valine in position 20 is replaced by methionine. The new hemoglobin mutant is designated hemoglobin Olympia (?20 (B2) valine ? methionine).

Stamatoyannopoulos, George; Nute, Peter E.; Adamson, John W.; Bellingham, A. J.; Funk, Donald

1973-01-01

311

Bile acid coenzyme A: amino acid N-acyltransferase in the amino acid conjugation of bile acids.  

PubMed

Bile acids are converted to their glycine and taurine N-acyl amidates by enzymes in the liver in a two-step process. This increases their aqueous solubility, particularly in the acidic environment of the upper part of the small intestine. Bile acid coenzyme A (CoA) thioesters synthesized by bile acid CoA ligase (see Shonsey et al., 2005) are substrates of bile acid CoA:amino acid N-acyltransferases (BAT) in the formation of bile acid N-acyl amidates. This chapter describes the methods used to purify BAT from human liver, to isolate and clone cDNAs encoding BAT from human, mouse, and rat liver cDNA libraries, the expression of BAT, the assays used to measure BAT activity, and the chemical syntheses of bile acid N-acylamidates. In addition, an enzyme that catalyzes further metabolism of glycine-conjugated bile acids is described. PMID:16399361

Shonsey, Erin M; Sfakianos, Mindan; Johnson, Michelle; He, Dongning; Falany, Charles N; Falany, Josie; Merkler, David J; Barnes, Stephen

2005-01-01

312

How much protein do parenteral amino acid mixtures provide?  

PubMed

It is commonly assumed that the weight of the amino acids in a parenteral amino acid mixture equals the amount of protein they provide. This assumption ignores the fact that the molecular weight of free amino acids is 18 mass units greater than when they are protein bound. The actual amount of protein substrate provided by commonly used free amino acid mixtures was determined by analyzing the amino acid composition of 3 commonly used parenteral amino acid solutions and the proteins that would be formed from them, and comparing the results with similar data from 3 nutritionally important proteins. After correction for hydration status, the ratio of essential amino acid mass to total mass of the amino acid mixtures was similar to albumin, myosin, and actin. However, all of the amino acid mixtures provided 17% less protein and energy than is now widely assumed. Current parenteral nutrition guidelines recommend 0.8-1.5 g mixed amino acids/kg normal weight per day, on the assumption that they are equivalent to formed proteins, but they are not equivalent. Clinicians who aim to provide 0.8-1.5 g protein/kg must administer 1.0-1.8 g mixed amino acids/kg. PMID:22011458

Hoffer, L John

2011-10-19

313

Organic geochemistry of amino acids: Precambrian to recent  

SciTech Connect

Since the discovery of amino acids in fossils (Abelson, 1954), considerable effort has been made to elucidate the origin and distribution of amino acids in geologic materials. Racemization and decomposition reactions of amino acids and peptides derived via the natural hydrolysis of protein constituents of organisms have been extensively studied. While the ubiquity of amino acids presents a challenge for discerning their indigeneity in geologic samples, careful analyses have resulted in successful applications of amino acid racemization and decomposition reactions for investigations of geochronologic, paleoclimatic, stratigraphic, diagenetic and chemotaxonomic problems for Quaternary age samples. An investigation of amino acids in sediments from Baffin Island fjords indicates that their distribution may also provide data with respect to the relative contributions of marine and terrigenous organic matter to recent sediments. While the absence of unstable amino acids and the presence of racemic amino acids in a sample may preclude very recent contamination, the possibility of retardation of amino acid racemization rates subsequent to geopolymer formation must also be considered. Studies of amino acids in Paleozoic, Mesozoic and early Cenozoic age samples are limited. Precambrian samples, however, have received much attention, given the potential (however slight) for isolating compounds representative of the earliest living systems. A future approach for elucidating the origin(s) of amino acids in ancient samples may be analyses of their individual stable isotopic compositions.

Engel, M.H.; Macko, S.A.

1985-01-01

314

Protein tolerance to random amino acid change  

PubMed Central

Mutagenesis of protein-encoding sequences occurs ubiquitously; it enables evolution, accumulates during aging, and is associated with disease. Many biotechnological methods exploit random mutations to evolve novel proteins. To quantitate protein tolerance to random change, it is vital to understand the probability that a random amino acid replacement will lead to a protein's functional inactivation. We define this probability as the “x factor.” Here, we develop a broadly applicable approach to calculate x factors and demonstrate this method using the human DNA repair enzyme 3-methyladenine DNA glycosylase (AAG). Three gene-wide mutagenesis libraries were created, each with 105 diversity and averaging 2.2, 4.6, and 6.2 random amino acid changes per mutant. After determining the percentage of functional mutants in each library using high-stringency selection (>19,000-fold), the x factor was found to be 34% ± 6%. Remarkably, reanalysis of data from studies of diverse proteins reveals similar inactivation probabilities. To delineate the nature of tolerated amino acid substitutions, we sequenced 244 surviving AAG mutants. The 920 tolerated substitutions were characterized by substitutability index and mapped onto the AAG primary, secondary, and known tertiary structures. Evolutionarily conserved residues show low substitutability indices. In AAG, ? strands are on average less substitutable than ? helices; and surface loops that are not involved in DNA binding are the most substitutable. Our results are relevant to such diverse topics as applied molecular evolution, the rate of introduction of deleterious alleles into genomes in evolutionary history, and organisms' tolerance of mutational burden.

Guo, Haiwei H.; Choe, Juno; Loeb, Lawrence A.

2004-01-01

315

Plasma-free amino acid profiling of cervical cancer and cervical intraepithelial neoplasia patients and its application for early detection.  

PubMed

In this study, plasma-free amino acid profiles were used to investigate pre-cancerous cervical intraepithelial neoplasia (CIN) and cervical squamous cell carcinoma (CSCC) metabolic signatures in plasma. Additionally, the diagnostic potential of these profiles was assessed, as well as their ability to provide novel insight into CSCC metabolism and systemic effects. Plasma samples from CIN patients (n = 26), CSCC patients (n = 22), and a control healthy group (n = 35) were analyzed by high-performance liquid chromatography, and their spectral profiles were subjected to the t test for statistical significance. Potential metabolic biomarkers were identified using database comparisons that examine the significance of metabolites. Compared with healthy controls, patients with CIN and CSCC demonstrated lower levels of plasma amino acids; plasma levels of arginine and threonine were increased in CIN patients but were decreased in cervical cancer patients. Additionally, the levels of a larger group of amino acids (aspartate, glutamate, asparagine, serine, glycine, histidine, taurine, tyrosine, valine, methionine, lysine, isoleucine, leucine, and phenylalanine) were gradually reduced from CIN to invasive cancer. These findings suggest that plasma-free amino acid profiling has great potential for improving cancer screening and diagnosis and for understanding disease pathogenesis. Plasma-free amino acid profiles may have the potential be used to determine cancer diagnoses in the early stage from a single blood sample and may enhance our understanding of its mechanisms. PMID:24068431

Hasim, Ayshamgul; Aili, Aixingzi; Maimaiti, Aminigul; Mamtimin, Batur; Abudula, Abulizi; Upur, Halmurat

2013-09-26

316

Amino acid preservation in saline halite core samples: Analogs for Martian dry evaporitic regions  

NASA Astrophysics Data System (ADS)

Recent data returned from several Mars spacecraft show substantial evidence for mineral precipitation from bodies of liquid water. Evaporitic minerals such as gypsum, kieserite and poly-hydrated magnesium sulfates have been detected remotely by orbiting spacecraft [1], jarosite has been detected in situ by the MER Opportunity [2], and chlorides are highly abundant upon the surface of Mars [3], often in correlation with siliclastic deposits [4]. Terrestrial environments can provide analogs for these systems identified on the Martian surface, and in-depth characterization of the terrestrial systems can provide valuable insights into processes that may have occurred on Mars during the late Noachian/early Hesperian. This is especially true in ancient playa or evaporative basin environments where deep core sampling offers a method of observing the geochemical diagenetic changes with time within a constrained environment. Deep coring can provide samples upwards of 200 ka within hundreds of meters of core [5]. The analysis of these sections can allow for the determination of preservation of various biosignatures from extinct microbial communities as well as their in situ diagenetic rates. Amino acids are powerful biomarkers that can be used to estimate biomass [6] and determine ages of extinct microbial communities [7]. Preliminary data for a core sample collected from Saline Valley, CA, shows the effect of time on amino acid biosignatures. The core has been dated by U-series: 35 feet, 20.9 ± 1.1 ka; 127 feet, 61.1 ±2.8 ka; 204 feet, 73.9 ±4.8 ka; and 310 feet, 150.3 ± 7.8 ka. The abundance of amino acids is observed to decrease drastically over the first 20 ka and then stabilize, although the overall composition changes. Acidic amino acids along with alanine and valine are the dominant amino acids. The enantiomeric (D/L) ratios generally increase with age because of in situ racemization, although the enantiomeric ratios for alanine and glutamic acid show a decrease in the deepest core section. This may indicate some recent amino acid contribution to the pool of certain amino acids. Racemization rates can be calculated from the equation: ln[(1+D/L)/(1-D/L)] - ln [(1+D/L)/(1-D/L)]t=0 = 2ki(time) where ki is the first-order rate constant for the interconversion of the enantiomers. Using the D/L ratios at the top of the core for the t = 0 term gives kasp = 3.5x10exp-5 y-1 and 1.3x10exp-5 y-1 for the 18 and 70 ka samples, respectively. For valine, the values are kval = 5.6x10exp-6 y-1 and 7.3x10exp-6 y-1. Extrapolating these values to the average surface temperatures on Mars indicates that the chirality of these amino acids would be preserved for billions of years. Thus, closed basin lacustrine and dry desert valley regions with evaporite-rich deposits are suitable environments in the search for preserved biosignatures on Mars. References [1] Bibring, J.P., et al., Science 307, 1576 (2005) [2] Klinghofer, G., et al., Science 306, 1740 (2004) [3] Osterloo, M.M., et al., Science 319, 1651 (2008) [4] Squyres, S.W., et al., Nature 443, E1 (2006) [5] Lowenstein, T.K., et al., Geology 27, 3 (1999) [6] Glavin, D., et al., Earth Planet. Sci. Lett. 185,1 (2001) [7] Aubrey, A. D., et al., in preparation, Nature Geo. Sci.

Bada, J.; Aubrey, A.; Lowenstein, T.; Timofeeff, M.

2008-12-01

317

From one amino acid to another: tRNA-dependent amino acid biosynthesis  

Microsoft Academic Search

Aminoacyl-tRNAs (aa-tRNAs) are the essential substrates for translation. Most aa-tRNAs are formed by direct aminoacylation of tRNA catalyzed by aminoacyl-tRNA synthetases. However, a smal- ler number of aa-tRNAs (Asn-tRNA, Gln-tRNA, Cys-tRNA and Sec-tRNA) are made by synthesizing the amino acid on the tRNA by first attaching a non-cognate amino acid to the tRNA, which is then converted to the cognate

Kelly Sheppard; Jing Yuan; Michael J. Hohn; Brian Jester; Kevin M. Devine; Dieter Soll

2008-01-01

318

Papaya proteinase IV amino acid sequence.  

PubMed

The amino acid sequence of papaya proteinase IV (PPIV), a major proteinase from the latex of Carica papaya [(1989) Biochem. J. 261, 469-476] is described. The enzyme has a high degree of sequence identity with papaya proteinase III, chymopapain and papain (81, 70 and 67%, respectively), and is clearly a member of the papain superfamily of cysteine proteinases. Nevertheless, the sequence shows substitution of certain residues conserved in all other known members of the superfamily. It is suggested that some of these substitutions may account for the unusual specificity of PPIV. PMID:2591528

Ritonja, A; Buttle, D J; Rawlings, N D; Turk, V; Barrett, A J

1989-11-20

319

Amino Acid Formation on Saturn's Inner Satellites  

NASA Astrophysics Data System (ADS)

Titan's atmosphere contributes nitrogen atoms and ions to the Saturnian magnetosphere. These ions have inward motion towards Saturn and should impact the inner satellites, thereby inducing a complex nitrogen oxides chemistry in the surfaces via their interaction with the water ice present. Species formed may include NO, NO2, NO3, HNO2, HNO3, NH2OH, HNO, NH, NH2, N2O, HNNO, and N2. If the surfaces also include CO2, then other species that may be formed as a result of N+ impact into H2O/CO2 ice will be HNCO, NCO and R-OCN. Successive reaction of HNCO with H and CO (which occur in irradiated H2O/CO2 ice) could lead to the smallest amino acid, glycine, in only 5 steps. Addition of CO to HNCO with successive hydrogenation of the oxygen atoms forms an -OH group with a C=O bond still present. Migration of the OH onto the C=O carbon yields a carboxylic acid group (-COOH). The HNCO -> Glycine conversion utilizes only simple and exothermic addition and rearrangement reactions. Both H and CO would be mobile in the water/CO2 ice crystal at the temperatures on the Saturnian satellites. Every step in the sequence is calculated to be exothermic, and the entire sequence is exothermic by a total of 231 kcal/mole. Therefore these sequences may occur under the temporary non-equilibrium conditions resulting from high-energy particle impact and subsequent residual heating. Glycine has its own radiolysis products, such as CHOCOOH (glyoxylic acid), CH3NH2 (methyl amine), HCHO, NH3, H2O2, and H2. Formation of higher-order amino acids, such as alanine and aminobutyric acids, might also occur, from solid-phase radiolysis or gas-phase ionic synthesis of combinations of some of the smaller molecules in the sequence.

Delitsky, M. L.; Lane, A. L.; Tidwell, T. T.; Henry-Riyad, H.

2002-09-01

320

Extraterrestrial amino acids in the Almahata Sitta meteorite  

NASA Astrophysics Data System (ADS)

Amino acid analysis of a meteorite fragment of asteroid 2008 TC3 called Almahata Sitta was carried out using reverse-phase liquid chromatography coupled with UV fluorescence detection and time-of-flight mass spectrometry (LC-FD/ToF-MS) as part of a sample analysis consortium. LC-FD/ToF-MS analyses of hot-water extracts from the meteorite revealed a complex distribution of two- to seven-carbon aliphatic amino acids and one- to three-carbon amines with abundances ranging from 0.5 to 149 parts-per-billion (ppb). The enantiomeric ratios of the amino acids alanine, ?-amino-n-butyric acid, 2-amino-2-methylbutanoic acid (isovaline), and 2-aminopentanoic acid (norvaline) in the meteorite were racemic (D/L ˜ 1), indicating that these amino acids are indigenous to the meteorite and not terrestrial contaminants. Several other nonprotein amino acids were also identified in the meteorite above background levels including ?-aminoisobutyric acid (?-AIB), 4-amino-2-methylbutanoic acid, 4-amino-3-methylbutanoic acid, and 3-, 4-, and 5-aminopentanoic acid. The total abundances of isovaline and ?-AIB in Almahata Sitta are approximately 1000 times lower than the abundances of these amino acids found in the CM carbonaceous chondrite Murchison. The extremely low abundances and unusual distribution of five-carbon amino acids in Almahata Sitta compared to CI, CM, and CR carbonaceous chondrites may reflect extensive thermal alteration of amino acids on the parent asteroid by partial melting during formation or subsequent impact shock heating. It is also possible that amino acids were synthesized by catalytic reactions on the parent body after asteroid 2008 TC3 cooled to lower temperatures, or introduced as a contaminant from unrelated meteorite clasts and chemically altered by ?-decarboxylation.

Glavin, Daniel P.; Aubrey, Andrew D.; Callahan, Michael P.; Dworkin, Jason P.; Elsila, Jamie E.; Parker, Eric T.; Bada, Jeffrey L.; Jenniskens, Peter; Shaddad, Muawia H.

2010-10-01

321

Available versus digestible amino acids - new stable isotope methods.  

PubMed

The nutritive value of food protein sources is dependent on the amino acid composition and the bioavailability of the nutritionally indispensable amino acids. Traditionally the methods developed to determine amino acid bioavailability have focused on intestinal absorption or digestibility, which is calculated as the percent of amino acid intake that does not appear in digesta or faeces. Traditional digestibility based methods do not always account for gut endogenous amino acid losses or absorbed amino acids which are unavailable due to the effect of heat processing and the presence of anti-nutritional factors, though methods have been developed to address these issues. Furthermore, digestibility based methods require the use of animal models, thus there is a need to develop in vivo methods that can be applied directly in human subjects to identify the proportion of dietary amino acids which is bioavailable, or metabolically available to the body for protein synthesis following digestion and absorption. The indicator amino acid oxidation (IAAO) method developed in our laboratory for humans has been systematically applied to determine almost all indispensable amino acid requirements in adult humans. Oxidation of the indicator amino acid is inversely proportional to whole body protein synthesis and responds rapidly to changes in the bioavailability of amino acids for metabolic processes. Using the IAAO concept, we developed a new in vivo method in growing pigs, pregnant sows and adult humans to identify the metabolic availability of amino acids in foods. The stable isotope based metabolic availability method is suitable for rapid and routine analysis in humans, and can be used to integrate amino acid requirement data with dietary amino acid availability of foods. PMID:23107543

Elango, Rajavel; Levesque, Crystal; Ball, Ronald O; Pencharz, Paul B

2012-08-01

322

Third system for neutral amino acid transport in a marine pseudomonad.  

PubMed Central

Uptake of leucine by the marine pseudomonad B-16 is an energy-dependent, concentrative process. Respiratory inhibitors, uncouplers, and sulfhydryl reagents block transport. The uptake of leucine is Na+ dependent, although the relationship between the rate of leucine uptake and Na+ concentration depends, to some extent, on the ionic strength of the suspending assay medium and the manner in which cells are washed prior to assay. Leucine transport can be separated into at least two systems: a low-affinity system with an apparent Km of 1.3 X 10(-5) M, and a high-affinity system with an apparent Km of 1.9 X 10(-7) M. The high-affinity system shows a specificity unusual for bacterial systems in that both aromatic and aliphatic amino acids inhibit leucine transport, provided that they have hydrophobic side chains of a length greater than that of two carbon atoms. The system exhibits strict stereospecificity for the L form. Phenylalanine inhibition was investigated in more detail. The Ki for inhibition of leucine transport by phenylalanine is about 1.4 X 10(-7) M. Phenylalanine itself is transported by an energy-dependent process whose specificity is the same as the high-affinity leucine transport system, as is expected if both amino acids share the same transport system. Studies with protoplasts indicate that a periplasmic binding protein is not an essential part of this transport system. Fein and MacLeod (J. Bacteriol. 124:1177-1190, 1975) reported two neutral amino acid transport systems in strain B-16: the DAG system, serving glycine, D-alanine, D-serine, and alpha-aminoisobutyric acid; and the LIV system, serving L-leucine, L-isoleucine, L-valine, and L-alanine. The high-affinity system reported here is a third neutral amino acid transport system in this marine pseudomonad. We propose the name "LIV-II" system.

Pearce, S M; Hildebrandt, V A; Lee, T

1977-01-01

323

Identification, purification, and characterization of a novel amino Acid racemase, isoleucine 2-epimerase, from lactobacillus species.  

PubMed

Accumulation of d-leucine, d-allo-isoleucine, and d-valine was observed in the growth medium of a lactic acid bacterium, Lactobacillus otakiensis JCM 15040, and the racemase responsible was purified from the cells and identified. The N-terminal amino acid sequence of the purified enzyme was GKLDKASKLI, which is consistent with that of a putative ?-aminobutyrate aminotransferase from Lactobacillus buchneri. The putative ?-aminobutyrate aminotransferase gene from L. buchneri JCM 1115 was expressed in recombinant Escherichia coli and then purified to homogeneity. The enzyme catalyzed the racemization of a broad spectrum of nonpolar amino acids. In particular, it catalyzed at high rates the epimerization of l-isoleucine to d-allo-isoleucine and d-allo-isoleucine to l-isoleucine. In contrast, the enzyme showed no ?-aminobutyrate aminotransferase activity. The relative molecular masses of the subunit and native enzyme were estimated to be about 49 kDa and 200 kDa, respectively, indicating that the enzyme was composed of four subunits of equal molecular masses. The Km and Vmax values of the enzyme for l-isoleucine were 5.00 mM and 153 ?mol·min(-1)·mg(-1), respectively, and those for d-allo-isoleucine were 13.2 mM and 286 ?mol·min(-1)·mg(-1), respectively. Hydroxylamine and other inhibitors of pyridoxal 5'-phosphate-dependent enzymes completely blocked the enzyme activity, indicating the enzyme requires pyridoxal 5'-phosphate as a coenzyme. This is the first evidence of an amino acid racemase that specifically catalyzes racemization of nonpolar amino acids at the C-2 position. PMID:24039265

Mutaguchi, Yuta; Ohmori, Taketo; Wakamatsu, Taisuke; Doi, Katsumi; Ohshima, Toshihisa

2013-09-13

324

Synthesis, antioxidative and antiviral activity of hydroxycinnamic acid amides of thiazole containing amino acid.  

PubMed

The synthesis and the biological (antioxidant and antiviral) activities of novel hydroxycinnamic acid amides of a thiazole containing TFA.valine-4-carboxylic acid ethyl ester are reported. The amides have been synthesized from p-coumaric, ferulic and sinapic acids with the corresponding TFA.valine-thiazole-4-carboxylic acid ethyl ester using the coupling reagent N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and 4-(dimethylamino) pyridine (DMAP) as a catalyst. The antioxidant properties of the newly synthesized amides have been studied for then antioxidative activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH)* test. The newly synthesized compounds have been tested against the replication in vitro of influenza virus A (H3N2) and human herpes virus 1 and 2 (HSV-1 and HSV-2). PMID:18853101

Stankova, Ivanka; Chuchkov, Kiril; Shishkov, Stoyan; Kostova, Kalina; Mukova, Luchia; Galabov, Angel S

2008-10-14

325

Amino acid analysis for meat protein evaluation.  

PubMed

The Food Safety and Inspection Service procedure for determination of essential amino acid content of mechanically processed products from red meat animals and poultry is based on hydrolysis of a powder prepared by blending samples in acetone-chloroform. The hydrolysis procedure incorporates thioglycolic acid to prevent loss of tryptophan. Aliquots of prepared hydrolysates are injected into a liquid chromatographic system, using gradient elution on an ion-exchange column for separation. The system also uses post-column hypochlorite oxidation coupled with orthophthalaldehyde reagent and fluorescence detection. Modification of the elution program allows concurrent determination of tryptophan with minimal added cost. Chromatograms from beef, pork, and poultry products show adequate separation and quantitation of beta-alanine, 1-methyl-histidine, and 3-methyl-histidine, indicating that the procedure could be used to estimate muscle content of products. A colorimetric procedure for assay of hydroxyproline was introduced and validated as an adjunct method for protein quality estimation. PMID:3558283

Ashworth, R B

326

Formation and transformation of amino acids and amino acid precursors by high-velocity impacts  

NASA Astrophysics Data System (ADS)

A wide variety of organic compounds have been found in extraterrestrial bodies such as comets and carbonaceous chondrites. It is plausible that these extraterrestrial bodies carried organic compounds such as amino acids or their precursors to the early Earth. It is claimed, however, that these extraterrestrial organics were destroyed during impacts to the Earth. We therefore examined possible transformation of amino acids and their precursors during high-velocity impacts by using a rail gun "HYPAC" in ISAS. Starting materials used in the impact experiments were (i) aqueous solution of glycine (10 mM or 1.0 M), and (ii) a mixture of ammonia, methanol and water. The target materials were sealed in stainless steel capsules, and shocked by impact with a polycarbonate projectile accelerated with "HYPAC" to the velocities of 2.5 - 7.0 km/s. A part of the products was acid-hydrolyzed. Both hydrolyzed an unhydrolyzed products were analyzed by mass spectrometry, high performance liquid chromatography and capillary electrophoresis and chromatography. When an aqueous solution containing ammonia, methanol and water was shocked by impact at the velocity of 6.4 km/s, a number of amino acids (e.g., serine and glycine) were detected after hydrolysis. The present results suggest that amino acid precursors could be formed during cometary impacts. When glycine solution was used as a starting material, about 40 % of glycine was recovered even after 6 km/s impact. Methylamine and ammonia, which are known as pyrolytic products of glycine, were detected, besides them, diketopiperazine and an unidentified product whose molecular weight was 134, were detected, while no glycine peptides were identified in them. It was shown that the impact processes resulted in the formation of amino acid condensates. Thermal stability of glycine precursor is comparable with glycine. The present results suggest that organic material could survive and/or formed during an impact process. Most of organic compounds in comets and carbonaceous chondrites were complex organic compounds. Laboratory simulations suggest that they contain precursors of amino acids. We are examining possible alteration of such complex precursors of amino acids by high-velocity impacts.

Kaneko, T.; Kobayashi, K.; Yamori, A.

327

Salts of amino acids with hexafluorosilicate anion  

NASA Astrophysics Data System (ADS)

In this work we present our preliminary results on the systematic search for salts of amino acids with hexafluorosilicate (SiF62-) anion. Three types of simple salts have been obtained: 2A+·SiF62- (2Gly+·SiF62-, 2L-Phe+·SiF62-, 2L-Val+·SiF62-, 2L-Glu+·SiF62-, 2L-His+·SiF62-), A2+·SiF62- (L-His2+·SiF62-, L-Lys2+·SiF62-, L-Orn2+·SiF62-) and 2(A···A+)·SiF62- (2(Bet···Bet+)·SiF62-). Furthermore, one example of mixed salts with different anions, including SiF62-, viz. 2L-His2+·2BF4-·SiF62-·2H2O is presented. It was found that the salts of amino acids with SiF62- anion tend to form crystal hydrates and the SiF62- anion is often disordered within the structures.

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

2013-01-01

328

Amino acid transport across the tonoplast of vacuoles isolated from barley mesophyll protoplasts: Uptake of alanine, leucine, and glutamine. [Hordeum vulgare L  

SciTech Connect

Mesophyll protoplasts from leaves of well-fertilized barley (Hordeum vulgare L.) plants contained amino acids at concentrations as high as 120 millimoles per liter. With the exception of glutamic acid, which is predominantly localized in the cytoplasm, a major part of all other amino acids was contained inside the large central vacuole. Alanine, leucine, and glutamine are the dominant vacuolar amino acids in barley. Their transport into isolated vacuoles was studied using {sup 14}C-labeled amino acids. Uptake was slow in the absence of ATP. A three- to sixfold stimulation of uptake was observed after addition of ATP or adenylyl imidodiphosphate an ATP analogue not being hydrolyzed by ATPases. Other nucleotides were ineffective in increasing the rate of uptake. ATP-Stimulated amino acid transport was not dependent on the transtonoplast pH or membrane potential. p-Chloromercuriphenylsulfonic acid and n-ethyl maleimide increased transport independently of ATP. Neutral amino acids such as valine or leucine effectively decreased the rate of alanine transport. Glutamine and glycine were less effective or not effective as competitive inhibitors of alanine transport. The results indicate the existence of a uniport translocator specific for neutral or basic amino acids that is under control of metabolic effectors.

Dietz, K.J.; Jaeger, R.; Kaiser, G.; Martinoia, E. (Institut fuer Botanik and Pharmazeutische Biologie der Universitaet, Wuerzburg (Germany, F.R.))

1990-01-01

329

The Component Combined Amino Acids of Some Marine Phytoplankton Species  

Microsoft Academic Search

Gas-liquid and thin-layer chromatography have been used for the determina­ tion of 25 amino acids in the hydrolysates of 25 species of marine phytoplankton which had been grown in Erd-Schreiber medium. The general pattern of their distribution agrees with that found by earlier workers; the principal amino acids being glutamic acid, alanine, leucine and aspartic acids. Small amounts of 2-amino­

Y. K. Chau; L. Chuecas; J. P. Riley

1967-01-01

330

Amino acid auxotrophs from protoplast cultures of Nicotiana plumbaginifolia , Viviani  

Microsoft Academic Search

Several amino acid requiring auxotrophs have been isolated from unsupplemented protoplast cultures of haploid Nicotiana plumbaginifolia following incubation with BUdR (1-5x10-5, 2 days) and recovery on complete medium. The auxotrophic lines required the following amino acid(s) for growth: his, ile, leu, ile+val, met or try. Met- is a new type isolated in higher plants. The same absolute amino acid requirement

I. Negrutiu; D. De Brouwer; R. Dirks; M. Jacobs

1985-01-01

331

Dietary Management of Stress Using Amino Acid Supplements  

Microsoft Academic Search

Amino acids, like carbohydrates and fatty acids, are basic nutrients. Twenty amino acids furnish the minimal requirements\\u000a for growth, nitrogen equilibrium, maintenance of host defenses, neural (Fernstrom, 2000; Young, El-Khoury, Melchor, & Castillo, 1994) and muscular functions, as well as gene-expression regulation (Fafournoux, Bruhat, & Jousse, 2000). The catabolism of amino acids provides an energy source via the intermediate products

Miro Smriga; Kunio Torii

332

Isoleucine and Valine Metabolism in Escherichia coli XXI. Mutations Affecting Derepression and Valine Resistance  

PubMed Central

The activity of acetohydroxy acid isomeroreductase, an essential enzyme for isoleucine and valine biosynthesis in Escherichia coli, was examined in a series of mutants containing derepressed levels of acetohydroxy acid synthetase activity but which differed from each other in the sensitivity of the synthetases to valine inhibition. The finding that isomeroreductase was highest in the strain with the synthetase that was least sensitive to valine inhibition supported the model of internal induction of the isomeroreductase by its acetohydroxy acid substrates. The mutation leading to the acetohydroxy acid synthetase least sensitive to valine was found to be unlinked to the ilv gene cluster and appeared to result in a synthetase that differed from the normal enzyme in several properties. The locus of this mutation is designated ilvF. The loci leading to derepression were designated azl. A pleiotropic, apparently single-step, mutation was found that led to restoration of end-product sensitivity to the synthetase, loss of end-product sensitivity of threonine deaminase [EC 4.2.1.16, l-threonine hydro-lyase (deaminating) and loss of isomeroreductase activity.

Pledger, W. J.; Umbarger, H. E.

1973-01-01

333

Deracemization of unnatural amino acid: homoalanine using D-amino acid oxidase and ?-transaminase.  

PubMed

A deracemization method was developed to generate optically pure L-homoalanine from racemic homoalanine using D-amino acid oxidase and ?-transaminase. A whole cell reaction using a biphasic system converted 500 mM racemic homoalanine to 485 mM L-homoalanine (>99% ee). PMID:22344532

Seo, Young-Man; Mathew, Sam; Bea, Han-Seop; Khang, Yong-Ho; Lee, Sang-Hyeup; Kim, Byung-Gee; Yun, Hyungdon

2012-02-20

334

Utilization of ?-Keto and ?-Hydroxy Analogues of Valine by the Growing Rat  

PubMed Central

When 70-80-g male albino rats eat a diet furnishing daily requirement of valine for optimal growth (70 ?mol/g) and all other nutrients (“complete diet”), they gain weight at an average rate of 3.0 g/100 g body wt/day. When valine is removed, they lose weight at an average 2.1 g/100 g body wt/day. The growth retardation is improved or corrected by adding valine to the diet, daily weight gain being proportional to dietary valine content over a range of 0-70 ?mol/g. Addition of ?-ketoisovaleric acid instead of valine to the valine-free diet also improves or corrects the growth failure. Percent efficiency of ?-ketoisovaleric acid as a substitute for valine was calculated as: 100 × (micromole valine per gram diet required to produce specified growth response)/(micromole ?-ketoisovaleric acid per gram diet required to produce the same response). Efficiency of the substitution is inversely related to dietary content of the keto analogue, being 80% when diet contains 17.5 ?mol/g (molar equivalent of ¼ the daily requirement of valine), and 37% when diet provides 140 ?mol/g (molar equivalent of twice the daily requirement of valine). ?-Hydroxyisovaleric acid also substitutes for valine. Efficiency of the substitution at the single ration tested, 70 ?mol/g diet, is 45%, similar to that for the keto analogue under the same conditions. When [1-14C]?-ketoisovaleric acid is injected intravenously, 30-80% of the administered radioactivity is exhaled as 14CO2 within 24 h. This finding suggests that inefficiency of ?-ketoisovaleric acid as a substitute for valine results in part from degradation of the keto acid to isobutyric acid by branched chain dehydrogenase-decarboxylase. Oral administration of neomycin, polymyxin, and bacitracin reduces efficiency of ?-ketoisovaleric acid as a substitute for valine by ¼-½. This effect suggests that transamination of the keto acid may be performed in part by gastrointestinal microbes.

Chawla, Rajender K.; Rudman, Daniel

1974-01-01

335

Synthesis, chemical and enzymatic hydrolysis, and aqueous solubility of amino acid ester prodrugs of 3-carboranyl thymidine analogs for boron neutron capture therapy of brain tumors.  

PubMed

Various water-soluble L-valine-, L-glutamate-, and glycine ester prodrugs of two 3-Carboranyl Thymidine Analogs (3-CTAs), designated N5 and N5-2OH, were synthesized for Boron Neutron Capture Therapy (BNCT) of brain tumors since the water solubilities of the parental compounds proved to be insufficient in preclinical studies. The amino acid ester prodrugs were prepared and stored as hydrochloride salts. The water solubilities of these amino acid ester prodrugs, evaluated in phosphate buffered saline (PBS) at pH 5, pH 6 and pH 7.4, improved 48-6600 times compared with parental N5 and N5-2OH. The stability of the amino acid ester prodrugs was evaluated in PBS at pH 7.4, Bovine serum, and Bovine cerebrospinal fluid (CSF). The rate of the hydrolysis in all three incubation media depended primarily on the amino acid promoiety and, to a lesser extend, on the site of esterification at the deoxyribose portion of the 3-CTAs. In general, 3'-amino acid ester prodrugs were less sensitive to chemical and enzymatic hydrolysis than 5'-amino acid ester prodrugs and the stabilities of the latter decreased in the following order: 5'-valine > 5'-glutamate > 5'-glycine. The rate of the hydrolysis of the 5'-amino acid ester prodrugs in Bovine CSF was overall higher than in PBS and somewhat lower than in Bovine serum. Overall, 5'-glutamate ester prodrug of N5 and the 5'-glycine ester prodrugs of N5 and N5-2OH appeared to be the most promising candidates for preclinical BNCT studies. PMID:22889558

Hasabelnaby, Sherifa; Goudah, Ayman; Agarwal, Hitesh K; abd Alla, Mosaad S M; Tjarks, Werner

2012-07-27

336

Formation of chromatographically unique species of transfer ribonucleic acid during amino acid starvation of relaxed-control Escherichia coli.  

PubMed Central

Examination of the transfer ribonucleic acid (tRNA) produced by starving, relaxed-control (rel minus) strains of Escherichia coli for required amino acids revealed the occurrence of a number of chromatographically unique subspecies. Leucine starvation results in the formation of new isoacceptor species of leucine-, histidine-, arginine-, valine-, and phenylalanine-specific tRNA and quantitative changes in the column profiles of serine, glycine, and isoleucine tRNA. Evidence that the unique tRNA species are synthesized de novo during amino acid starvation comes from the findings that the major unique leucine isoacceptor species is not formed in stringent control cells or in rel minus cells starved for uracil or treated with rifampin. Furthermore, heat treatment of the unique leucine tRNA does not alter its chromatographic behavior, indicating that the species is not an aggregate or nuclease-damaged form of a normal isoacceptor tRNA. The methyl acceptor activities of tRNA from leucine-starved and nonstarved rel+ or rel minus cells were found to be essentially the same. This result and the finding that the chromatographic behavior of the unique leucine-specific tRNA was not altered after treatment with tRNA methylase suggests that gross methyl deficiency is probably not the biochemical basis for the occurrence of the unique species.

Fournier, M J; Peterkofsky, A

1975-01-01

337

Role of acidic and aromatic amino acids in Rhodobacter capsulatus cytochrome c1. A site-directed mutagenesis study.  

PubMed

The roles of two evolutionarily conserved aromatic residues in the cytochrome c(1) component of the Rhodobacter capsulatus cytochrome bc(1) complex, phenylalanine 138 and tyrosine 194, were analyzed by site-directed mutagenesis, in combination with biophysical and biochemical measurements. Changing Phe138 to either alanine or valine, but not to tyrosine, results in redox heterogeneity of cytochrome c(1). Replacement of Phe138 by an aliphatic amino acid also caused changes in the EPR spectrum of the cytochrome and resulted in decreases in the steady-state V(max) for the hydroquinone/cytochrome c oxidoreductase activity of cytochrome bc(1) complexes containing the mutated cytochrome c(1). These findings indicate that the presence of an aromatic residue at position 138 is essential for maintaining the native environment of the cytochrome c(1) heme. In contrast, replacement of Tyr194 by aliphatic amino acids had no significant effect on either the E(m) of cytochrome c(1) or the steady-state activity parameters. Site-directed mutagenesis of glutamate and aspartate residues in a conserved acidic patch (region 2) on Rb. capsulatus cytochrome c(1) suggests that these negatively charged residues do not play a role in the docking of cytochrome c(2) with the cytochrome bc(1) complex. PMID:12873143

Li, Jun; Osyczka, Artur; Conover, Richard C; Johnson, Michael K; Qin, Hong; Daldal, Fevzi; Knaff, David B

2003-07-29

338

Evaluation of bioavailability of individual amino acids in Diplodus puntazzo larvae: Towards the ideal dietary amino acid profile  

Microsoft Academic Search

The indispensable AA profile of fish carcass has been commonly used as a good indicator of fish amino acids requirements. Amino acids composition of the whole body tissue of Diplodus puntazzo was determined for the larval ages of 5, 9, 12, 17, 25 and 35 days after hatching (DAH).No significant differences were found during this species ontogeny for any indispensable amino

M. Saavedra; M. Beltran; P. Pousão-Ferreira; M. T. Dinis; J. Blasco; L. E. C. Conceição

2007-01-01

339

Synthesis of Essential Amino Acids from Their ?-Keto Analogues by Perfused Rat Liver and Muscle  

PubMed Central

Most essential amino acids can be replaced by their ?-keto-analogues in the diet. These ketoacids have therefore been proposed as substitutes for dietary protein. In order to determine their fate in tissues of normal animals, isolated rat liver and hindquarter (muscle) preparations were perfused with keto-analogues of valine, leucine, isoleucine, methionine, or phenylalanine. When perfused at 1.5-2.0 mM, all five compounds were utilized rapidly by the liver of 48-h starved rats, at rates varying from 49 to 155 ?mol/h per 200g rat. The corresponding amino acids appeared in the medium in significantly increased concentrations. Perfusion with phenylpyruvate also led to the appearance of tyrosine. Urea release was unaltered. Measurement of metabolite concentrations in freeze-clamped liver revealed two abnormalities, particularly at ketoacid concentrations of 5 mM or above: a large increase in ?-ketoglutarate, and a moderate to marked decrease in tissue glutamine. This decrease was quantitatively sufficient to account for nitrogen appearing in newly synthesized amino acids. Isolated hindquarters of fed rats were perfused with the same ketoacids at concentrations of 1.3-8.0 mM. All were utilized at rates varying from 1.4 to 7.0 ?mol/h per g muscle perfused. The corresponding amino acids were released at greatly increased rates. Alanine and glutamate levels fell in some perfusions, but the principal nitrogen donor in muscle was not identified; the content of glutamine in tissue, and its rate of release into the perfusate remained constant.

Walser, Mackenzie; Lund, Patricia; Ruderman, Neil B.; Coulter, A. W.

1973-01-01

340

Fatty Acid Production from Amino Acids and ?-Keto Acids by Brevibacterium linens BL2†  

PubMed Central

Low concentrations of branched-chain fatty acids, such as isobutyric and isovaleric acids, develop during the ripening of hard cheeses and contribute to the beneficial flavor profile. Catabolism of amino acids, such as branched-chain amino acids, by bacteria via aminotransferase reactions and ?-keto acids is one mechanism to generate these flavorful compounds; however, metabolism of ?-keto acids to flavor-associated compounds is controversial. The objective of this study was to determine the ability of Brevibacterium linens BL2 to produce fatty acids from amino acids and ?-keto acids and determine the occurrence of the likely genes in the draft genome sequence. BL2 catabolized amino acids to fatty acids only under carbohydrate starvation conditions. The primary fatty acid end products from leucine were isovaleric acid, acetic acid, and propionic acid. In contrast, logarithmic-phase cells of BL2 produced fatty acids from ?-keto acids only. BL2 also converted ?-keto acids to branched-chain fatty acids after carbohydrate starvation was achieved. At least 100 genes are potentially involved in five different metabolic pathways. The genome of B. linens ATCC 9174 contained these genes for production and degradation of fatty acids. These data indicate that brevibacteria have the ability to produce fatty acids from amino and ?-keto acids and that carbon metabolism is important in regulating this event.

Ganesan, Balasubramanian; Seefeldt, Kimberly; Weimer, Bart C.

2004-01-01

341

A review of the role of acid-base balance in amino acid nutrition  

Microsoft Academic Search

ABSTRACT Acid-base balance and amino acid metabolism are intimately related. Changes in acid-base balance influence the metabolic fate of many amino acids. Also, acid-base homeostasis is achieved in part by alteration of amino acid metabolism, not only in the kidney, but also in liver, muscle and splanchnic tissue. Glutamine is the primary amino acid involved in renal ammonia- genesis, a

J. F. Patience; J. E Patience

2010-01-01

342

Repeated post-exercise administration with a mixture of leucine and glucose alters the plasma amino acid profile in Standardbred trotters  

PubMed Central

Background The branched chain amino acid leucine is a potent stimulator of insulin secretion. Used in combination with glucose it can increase the insulin response and the post exercise re-synthesis of glycogen in man. Decreased plasma amino acid concentrations have been reported after intravenous or per oral administration of leucine in man as well as after a single per oral dose in horses. In man, a negative correlation between the insulin response and the concentrations of isoleucine, valine and methionine have been shown but results from horses are lacking. This study aims to determine the effect of repeated per oral administration with a mixture of glucose and leucine on the free amino acid profile and the insulin response in horses after glycogen-depleting exercise. Methods In a crossover design, after a glycogen depleting exercise, twelve Standardbred trotters received either repeated oral boluses of glucose, 1 g/kg body weight (BW) at 0, 2 and 4 h with addition of leucine 0.1 g/kg BW at 0 and 4 h (GLU+LEU), or repeated boluses of water at 0, 2 and 4 h (CON). Blood samples for analysis of glucose, insulin and amino acid concentrations were collected prior to exercise and over a 6 h post-exercise period. A mixed model approach was used for the statistical analyses. Results Plasma leucine, isoleucine, valine, tyrosine and phenylalanine concentrations increased after exercise. Post-exercise serum glucose and plasma insulin response were significantly higher in the GLU+LEU treatment compared to the CON treatment. Plasma leucine concentrations increased after supplementation. During the post-exercise period isoleucine, valine and methionine concentrations decreased in both treatments but were significantly lower in the GLU+LEU treatment. There was no correlation between the insulin response and the response in plasma leucine, isoleucine, valine and methionine. Conclusions Repeated post-exercise administration with a mixture of leucine and glucose caused a marked insulin response and altered the plasma amino acid profile in horses in a similar manner as described in man. However, the decreases seen in plasma amino acids in horses seem to be related more to an effect of leucine and not to the insulin response as seen in man.

2012-01-01

343

Substrate specificity of the amino acid transporter PAT1  

Microsoft Academic Search

Summary.  The proton coupled amino acid transporter PAT1 expressed in intestine, brain, and other organs accepts L- and D-proline, glycine,\\u000a and L-alanine but also pharmaceutically active amino acid derivatives such as 3-amino-1-propanesulfonic acid, L-azetidine-2-carboxylic\\u000a acid, and cis-4-hydroxy-D-proline as substrates. We systematically analyzed the structural requirements for PAT1 substrates\\u000a by testing 87 amino acids, proline homologs, indoles, and derivatives. Affinity data and

L. Metzner; K. Neubert; M. Brandsch

2006-01-01

344

Metabolic Responses of Saccharomyces cerevisiae to Valine and Ammonium Pulses during Four-Stage Continuous Wine Fermentations  

PubMed Central

Nitrogen supplementation, which is widely used in winemaking to improve fermentation kinetics, also affects the products of fermentation, including volatile compounds. However, the mechanisms underlying the metabolic response of yeast to nitrogen additions remain unclear. We studied the consequences for Saccharomyces cerevisiae metabolism of valine and ammonium pulses during the stationary phase of four-stage continuous fermentation (FSCF). This culture technique provides cells at steady state similar to that of the stationary phase of batch wine fermentation. Thus, the FSCF device is an appropriate and reliable tool for individual analysis of the metabolic rerouting associated with nutrient additions, in isolation from the continuous evolution of the environment in batch processes. Nitrogen additions, irrespective of the nitrogen-containing compound added, substantially modified the formation of fermentation metabolites, including glycerol, succinate, isoamyl alcohol, propanol, and ethyl esters. This flux redistribution, fulfilling the requirements for precursors of amino acids, was consistent with increased protein synthesis resulting from increased nitrogen availability. Valine pulses, less efficient than ammonium addition in increasing the fermentation rate, were followed by a massive conversion of this amino acid in isobutanol and isobutyl acetate through the Ehrlich pathway. However, additional routes were involved in valine assimilation when added in stationary phase. Overall, we found that particular metabolic changes may be triggered according to the nature of the amino acid supplied, in addition to the common response. Both these shared and specific modifications should be considered when designing strategies to modulate the production of volatile compounds, a current challenge for winemakers.

Clement, T.; Perez, M.; Mouret, J. R.; Sanchez, I.; Sablayrolles, J. M.

2013-01-01

345

Simultaneous separation of jasmonic acid conjugates with amino acids by MEKC.  

PubMed

Jasmonic acid (JA) conjugates with amino acids (AAs) are a group of plant hormone in the family of jasmonates. The separation of stereoisomers of JA-AA conjugates is a very challenging work since these stereoisomers have similar chromatographic and electrophoretic behavior. Simultaneous separation of ten (±)-JA conjugates with five AAs including L-Tyr (tyrosine), L-leucine, L-Ile (isoleucine), L-valine, and L-phenylalanine and their stereoisomers has been achieved by MEKC with diode array detector in this work. Optimum separation of the analytes was obtained on a 61.5 cm × 75 ?m id capillary using a running buffer containing 80 mM SDS and 50 mM phosphates (pH 7.0) at +18 kV applied voltage and capillary temperature of 35°C. Ten stereoisomers of JA conjugates with five AAs are completely separated in 13 min. The RSDs of the migration times and peak areas of the ten stereoisomers were in the range of 0.48-1.03% and 1.03-2.07%, respectively. In the tested concentration range, good linear relationships (correlation coefficients above 99%) between peak areas and concentrations of the analytes were observed. The proposed method has been successfully applied to the analysis of spiked rice floret sample and original reaction solution of (±)-JA-Ile conjugate and (±)-JA-Tyr conjugate. The recoveries ranged from 91.7 to 107.6% for the rice floret sample and 92.9 to 107.2% for the original reaction solution. PMID:23483735

Chen, Ying; Chen, Zilin

2013-03-01

346

Comparative Genomics of Regulation of Fatty Acid and Branched-chain Amino Acid Utilization in Proteobacteria  

SciTech Connect

Bacteria can use branched-chain amino acids (ILV, i.e. isoleucine, leucine, valine) and fatty acids (FA) as sole carbon and energy sources convering ILV into acetyl-CoA, propanoyl-CoA and propionyl-CoA, respectively. In this work, we used the comparative genomic approach to identify candidate transcriptional factors and DNA motifs that control ILV and FA utilization pathways in proteobacteria. The metabolic regulons were characterized based on the identification and comparison of candidate transcription factor binding sites in groups of phylogenetically related genomes. The reconstructed ILV/FA regulatory network demonstrates considerable variability and involves six transcriptional factors from the MerR, TetR and GntR families binding to eleven distinct DNA motifs. The ILV degradation genes in gamma- and beta-proteobacteria are mainly regulated by anovel regulator from the MerR family (e.g., LiuR in Pseudomonas aeruginosa) (40 species), in addition, the TetR-type regulator LiuQ was identified in some beta-proteobacteria (8 species). Besides the core set of ILV utilization genes, the LiuR regulon in some lineages is expanded to include genes from other metabolic pathways, such as the glyoxylate shunt and glutamate synthase in the Shewanella species. The FA degradation genes are controlled by four regulators including FadR in gamma-proteobacteria (34 species), PsrA in gamma- and beta-proteobacteria (45 species), FadP in beta-proteobacteria (14 species), and LiuR orthologs in alpha-proteobacteria (22 species). The remarkable variability of the regulatory systems associated with the FA degradation pathway is discussed from the functional and evolutionary points of view.

Kazakov, Alexey E.; Rodionov, Dmitry A.; Arkin, Adam Paul; Dubchak, Inna; Gelfand, Mikhail S.; Alm, Eric

2008-10-31

347

Transport of Aromatic Amino Acids by Pseudomonas aeruginosa  

PubMed Central

Kinetic studies of the transport of aromatic amino acids by Pseudomonas aeruginosa revealed the existence of two high-affinity transport systems which recognized the three aromatic amino acids. From competition data and studies on the exchange of preformed aromatic amino acid pools, the first transport system was found to be functional with phenylalanine, tyrosine, and tryptophan (in order of decreasing activity), whereas the second system was active with tryptophan, phenylalanine, and tyrosine. The two systems also transported a number of aromatic amino acid analogues but not other amino acids. Mutants defective in each of the two and in both transport systems were isolated and described. When the amino acids were added at low external concentrations to cells growing logarithmically in glucose minimal medium, the tryptophan pool very quickly became saturated. Under identical conditions, phenylalanine and tyrosine each accumulated in the intracellular pool of P. aeruginosa at a concentration which was 10 times greater than that of tryptophan.

Kay, W. W.; Gronlund, Audrey F.

1971-01-01

348

Amino acids as chiral selectors in enantioresolution by liquid chromatography.  

PubMed

Amino acids are unique in terms of their structural features and multidimensional uses. With their simple structures and the ready availability of both enantiomers, amino acids not only serve as a chiral pool for synthesis but also provide an inexpensive pool for resolution studies. There has been no attempt to review the application of amino acids as chiral selectors for chromatographic enantioresolution of pharmaceuticals and other compounds. The present paper deals with application of l-amino acids and complexes of l-amino acids with a metal ion, particularly Cu(II), as an impregnating reagent in thin-layer chromatography or as a chiral ligand exchange reagent or a chiral mobile phase additive in both thin-layer chromatography and high-performance liquid chromatography. Enantiomeric resolution of ?-blockers, nonsteroidal anti-inflammatories, amino acids (and their derivatives) and certain other compounds is discussed. PMID:22729784

Bhushan, Ravi; Dixit, Shuchi

2012-06-25

349

Some Factors Which Affect Amino Acid Uptake by Saccharomyces carlsbergensis  

PubMed Central

When fully grown cells of Saccharomyces carlsbergensis were suspended in a solution of glucose and labeled amino acids, there was a lag phase before rapid uptake of certain amino acids. During this lag, significant amounts of sugar were utilized. The lag phase varied in length, depending upon the amino acid under study, but could be shortened by aeration of the cells and eliminated by their preincubation in glucose solution. Divalent metal ions, especially Ca2+ added during the early stages of the lag phase, increased the length of the lag, an effect that could be reversed by washing with ethylenediaminetetraacetate, but amino acids which normally showed little or no lag before uptake were insensitive to Ca2+. The rate of uptake of amino acids or of sugar was essentially unaffected by Ca2+, whereas 2,4-dinitrophenol caused an overall decrease in the rate of uptake of all amino acids tested. The relevance of these observations to commercial brewing practice is shown.

Romkes, S. C. E.; Lewis, M. J.

1971-01-01

350

Lipid-Amino Acid Conjugates and Methods of Use.  

National Technical Information Service (NTIS)

N-fatty acid-amino acid conjugates and J(sub 2) prostanoid-amino acid conjugates are disclosed along with methods for making such conjugates and methods of using these conjugates in the treatment of conditions that involve dysfunctional lipid metabolism, ...

R. B. Zurier S. H. Burstein

2005-01-01

351

Protein engineering with unnatural amino acids.  

PubMed

Protein engineering has become an extensively used tool in many fields, allowing us to probe protein function, characterize proteins using a range of biophysical techniques, chemically modify proteins and improve protein function for medical and industrial applications. It is now possible to site-specifically incorporate unnatural, or non-canonical, amino acids (uAAs) into proteins, which has had a major impact on protein engineering. In this review, we discuss the recent technical developments in the field and how uAA-protein engineering is becoming an increasingly valuable molecular tool, with the unique chemical functionalities of some uAAs allowing a range of otherwise impossible experiments to be performed. Finally, the impediments that have resulted in a relatively small number of recent studies in which uAA-protein engineering has been used to improve protein function are discussed, alongside some of the recent technical developments that may serve to overcome these obstacles. PMID:23835227

Zhang, William H; Otting, Gottfried; Jackson, Colin J

2013-07-05

352

Synthesis of alpha-amino acids  

DOEpatents

A method is described for synthesizing alpha amino acids proceeding through novel intermediates of the formulas: R[sub 1]R[sub 2]C(OSOCl)CN, R[sub 1]R[sub 2]C(Cl)CN and [R[sub 1]R[sub 2]C(CN)O][sub 2]SO wherein R[sub 1] and R[sub 2] are each selected from hydrogen monovalent substituted and unsubstituted hydrocarbon radicals of 1 to 10 carbon atoms. The use of these intermediates allows the synthesis steps to be exothermic and results in an overall synthesis method which is faster than the synthesis methods of the prior art. No Drawings

Davis, J.W. Jr.

1983-01-25

353

Coherent manipulation of free amino acids fluorescence.  

PubMed

Coherent manipulation of molecular wavepackets in biomolecules might contribute to the quest towards label-free cellular imaging and protein identification. We report the use of optimally tailored UV laser pulses in pump-probe depletion experiments that selectively enhance or decrease fluorescence between two aromatic amino acids: tryptophan (Trp) and tyrosine (Tyr). Selective fluorescence modulation is achieved with a contrast of ~35%. A neat modification of the time-dependent fluorescence depletion signal of Trp is observed, while the Tyr transient trace remains unchanged. The mechanism invoked for explaining the change of the depletion of Trp is a less efficient coupling between the fluorescing state and the higher non-radiative excited states by the optimally shaped pulse, than by the reference pulse. PMID:22395710

Rondi, A; Bonacina, L; Trisorio, A; Hauri, C; Wolf, J-P

2012-03-06

354

Inhibitors of D-amino acid oxidase  

US Patent & Trademark Office Database

The present invention provides novel inhibitors of the enzyme D-amino acid oxidase. The compounds of the invention are useful for treating or preventing diseases and/or condition, wherein modulation of D-serine levels, and/or its oxidative products, is effective in ameliorating symptoms. The invention further provides methods of enhancing learning, memory and/or cognition. For example, the invention provides methods for treating or preventing loss of memory and/or cognition associated with neurodegenerative diseases, such as Alzheimer's disease. The invention further provides methods for preventing loss of neuronal function characteristic of neurodegenerative diseases. In addition, methods are provided for the treatment or prevention of neuropsychiatric diseases (e.g., schizophrenia) and for the treatment or prevention of pain and ataxia.

2011-03-08

355

Growth, carcass traits, and plasma amino acid concentrations of gilts fed low-protein diets supplemented with amino acids including histidine, isoleucine, and valine1,2  

Microsoft Academic Search

Three experiments were conducted to determine thefifth-limiting aminoacid forgrowing pigs in an 11% CP, corn-soybean meal diet. In each experi- ment, 36 gilts (initial weight 19.5, 21.9, and 21.0 kg, respectively) were penned individually and fed one of six diets in a randomized block design for 35 d. Diets containing 16, 12, and 11% CP were fed in each experi-

J. L. Figueroa; A. J. Lewis; P. S. Miller; R. L. Fischer; R. M. Diedrichsen

356

Characterization of Amino Acid Efflux from Isolated Soybean Cells 1  

PubMed Central

Cells from reproductive soybean (Glycine max [L.] Merr.) plants were isolated using a mechanical-enzymic technique that produced a high yield of uniform, physiologically active cells. Cells were incubated in a pH 6.0 buffered solution and subjected to various treatments in order to determine the nature of net amino acid efflux. Total net amino acid (ninhydrinreactive substances) efflux was not affected by the following conditions: (a) darkness, (b) aeration, (c) K+ concentrations of 0.1, 1.0, 10, or 100 millimolar and (d) pH 4, 5, 6, 7, or 8. The Q10 for net amino acid efflux between 10°C and 30°C was 1.6. Thus, it seems that net amino acid efflux requires neither current photosynthetic energy nor a pH/ion concentration gradient. Amino acid analyses of the intra-and extracellular fractions over time showed that each amino acid was exported linearly for at least 210 minutes, but that export rate was not necessarily related to internal amino acid pools. Amino acids that were exported fastest were alanine, lysine, leucine, and glycine. Addition of the inhibitor p-chloromercuriphenyl sulfonic acid, 3(3,4-dichlorophenyl)-1,1-dimethylurea, or carbonylcyanide p-trifluoromethoxyphenylhydrazone increased the rate of total amino acid efflux but had specific effects on the efflux of certain amino acids. For example, p-chloromercuriphenyl sulfonic acid greatly enhanced efflux of ?-aminobutyric acid, which is not normally exported rapidly even though a high concentration normally exists within cells. The data suggest that net amino acid efflux is a selective diffusional process. Because net efflux is the result of simultaneous efflux and influx, we propose that efflux is a facilitated diffusion process whereas influx involves energy-dependent carrier proteins.

Secor, Jacob; Schrader, Larry E.

1984-01-01

357

A new synthetic protocol for coumarin amino acid  

PubMed Central

Summary The hydrochloride of the racemic amino acid (2-(7-hydroxycoumarin-4-yl)ethyl)glycine, which can serve as a fluorescent probe in proteins, and two halogen derivatives of it, were synthesized by using a new synthetic protocol in five steps. It is less costly and relatively easy to prepare this kind of fluorescent amino acid with the new synthetic method. Furthermore, it can be applied to synthesize other derivatives of the coumarin amino acid with some specific properties.

Xu, Xinyi

2013-01-01

358

From ? -lactams to ? - and ? -amino acid derived peptides  

Microsoft Academic Search

Summary The potential ofß-lactams as intermediates for the access toa- andß-amino acid-derived peptides is shortly reviewed, with major focus on the technologies developed in our group. The two general strategies lie, on one side, in the oxidative ring expansion of 3-hydroxyß-lactams toN-carboxya-amino acid anhydrides or Leuch's anhydrides and subsequent coupling witha-amino acid esters and, on the other side, in the

Claudio Palomo; J. M. Aizpurua; I. Ganboa; M. Oiarbide

1999-01-01

359

Which Amino Acids Should Be Used in Prebiotic Chemistry Studies?  

Microsoft Academic Search

The adsorption of amino acids on minerals and their condensation under conditions that resemble those of prebiotic earth is\\u000a a well studied subject. However, which amino acids should be used in these experiments is still an open question. The main\\u000a goal of this review is to attempt to answer this question. There were two sources of amino acids for the

Dimas A. M. Zaia; Cássia Thaïs B. V. Zaia; Henrique De Santana

2008-01-01

360

Chiral Analysis of Amino Acids Using Electrochemical Composite Bienzyme Biosensors  

Microsoft Academic Search

The construction and performance of bienzyme amperometric composite biosensors for the selective determination of l- or d-amino acids is reported. d- or l-Amino acid oxidase, horseradish peroxidase, and the mediator ferrocene were coimmobilized by simple physical inclusion into the bulk of a graphite–70% Teflon electrode matrix. Working conditions including amino acid oxidase loading and pH were optimized. Studies on the

R. Dom??nguez; B. Serra; A. J. Reviejo; J. M. Pingarrón

2001-01-01

361

Amino acid transport in the renal proximal tubule  

Microsoft Academic Search

Summary.   In the kidney the proximal tubule is responsible for the uptake of amino acids. This occurs via a variety of functionally\\u000a and structurally different amino acid transporters located in the luminal and basolateral membrane. Some of these transporters\\u000a show an ion-dependence (e.g. Na+, Cl? and K+) or use an H+-gradient to drive transport. Only a few amino acid transporters

T. Gonska; J. R. Hirsch; E. Schlatter

2000-01-01

362

Stardust, supernovae, neutrinos and the chirality of the amino acids  

NASA Astrophysics Data System (ADS)

A mechanism for creating amino acid enantiomerism that involves selection of one chirality by interactions with the neutrinos from a core-collapse supernova is defined. This selection mechanism involves the alignment between the spins of the neutrinos and of the 14N nuclei in the amino acids, or in precursor molecules, which in turn couple to the molecular chirality. Details of the chiral selection, as well as the subsequent chemical evolution and galactic mixing that would ultimately populate the Galaxy with the selected species are discussed. The resulting amino acids could either be the source thereof on Earth or could have produced the chirality that was ultimately achieved for Earthly amino acids.

Boyd, R. N.; Kajino, T.; Onaka, T.

2012-12-01

363

Which Amino Acids Should Be Used in Prebiotic Chemistry Studies?  

NASA Astrophysics Data System (ADS)

The adsorption of amino acids on minerals and their condensation under conditions that resemble those of prebiotic earth is a well studied subject. However, which amino acids should be used in these experiments is still an open question. The main goal of this review is to attempt to answer this question. There were two sources of amino acids for the prebiotic earth: (1) exogenous—meaning that the amino acids were synthesized outside the earth and delivered to our planet by interplanetary dust particles (IDPs), meteorites, comets, etc. and (2) endogenous—meaning that they were synthesized on earth in atmospheric mixtures, hydrothermal vents, etc. For prebiotic chemistry studies, the use of a mixture of amino acids from both endogenous and exogenous sources is suggested. The exogenous contribution of amino acids to this mixture is very different from the average composition of proteins, and contains several non-protein amino acids. On the other hand, the mixture of amino acids from endogenous sources is seems to more closely resemble the amino acid composition of terrestrial proteins.

Zaia, Dimas A. M.; Zaia, Cássia Thaïs B. V.; de Santana, Henrique

2008-12-01

364

Recent advances in microchip electrophoresis for amino acid analysis.  

PubMed

With the maturation of microfluidic technologies, microchip electrophoresis has been widely employed for amino acid analysis owing to its advantages of low sample consumption, reduced analysis time, high throughput, and potential for integration and automation. In this article, we review the recent progress in amino acid analysis using microchip electrophoresis during the period from 2007 to 2012. Innovations in microchip materials, surface modification, sample introduction, microchip electrophoresis, and detection methods are documented, as well as nascent applications of amino acid analysis in single-cell analysis, microdialysis sampling, food analysis, and extraterrestrial exploration. Without doubt, more applications of microchip electrophoresis in amino acid analysis may be expected soon. PMID:23436170

Ou, Gaozhi; Feng, Xiaojun; Du, Wei; Liu, Xin; Liu, Bi-Feng

2013-02-24

365

Far infrared spectra of solid state aliphatic amino acids in different protonation states  

NASA Astrophysics Data System (ADS)

Far infrared spectra of zwitterionic, cationic, and anionic forms of aliphatic amino acids in solid state have been studied experimentally. Measurements were done on glycine, L-alanine, L-valine, L-leucine, and L-isoleucine powder samples and film samples obtained from dried solutions prepared at pH ranging from 1 to 13. Solid state density functional theory calculations were also performed, and detailed potential energy distributions were obtained from normal mode results. A good correspondence between experimental and simulated spectra was achieved and this allowed us to propose an almost complete band assignment for the far infrared spectra of zwitterionic forms. In the 700-50 cm-1 range, three regions were identified, each corresponding to a characteristic set of normal modes. A first region between 700 and 450 cm-1 mainly contained the carboxylate bending, rocking, and wagging modes as well as the ammonium torsional mode. The 450-250 cm-1 region was representative of backbone and sidechain skeletal bending modes. At last, the low wavenumber zone, below 250 cm-1, was characteristic of carboxylate and skeletal torsional modes and of lattice modes. Assignments are also proposed for glycine cationic and anionic forms, but could not be obtained for all aliphatic amino acids due to the lack of structural data. This work is intended to provide fundamental information for the understanding of peptides vibrational properties.

Trivella, Aurélien; Gaillard, Thomas; Stote, Roland H.; Hellwig, Petra

2010-03-01

366

Novel amino acids: synthesis of furoxan and sydnonimine containing amino acids and peptides as potential nitric oxide releasing motifs.  

PubMed

The incorporation of furoxan and sydnonimine ring systems into amino acid side chains is demonstrated with the preparation of four novel amino acids which carry these nitric oxide-releasing motifs. N-((4-Nitrophenoxy)carbonyl)-3-phenylsydnonimine 9 and bis(phenylsulfonyl)furoxan 10 are the key intermediates for introducing the heterocycle side chains onto appropriate amine and alcohol functionalities respectively. Furoxan 5 and 7 both displayed NO release based on determination of nitrite production. Orthogonal amino acid protecting group strategies were deployed to demonstrate that the amino acids could be incorporated into peptide frameworks. By way of demonstration the amino acids were placed centrally into several tripeptide motifs. Griess test assays showed that these amino acids released NO in the presence of ?-glutathione (GST). PMID:23753002

Nortcliffe, Andrew; Botting, Nigel P; O'Hagan, David

2013-06-10

367

Thirteen-week oral toxicity study of branched-chain amino acids in rats.  

PubMed

Branched-chain amino acids (L-isoleucine, L-valine, and L-leucine) are being increasingly used in sport supplements. This study evaluated toxicological and behavioral effects of L-isoleucine (Ile), L-valine (Val), and L-leucine (Leu) during a dosing study with male and female Sprague-Dawley rats. The amino acids were incorporated into a standard diet at doses equal to 1.25%, 2.5%, and 5.0% (w/w). A control group of rats received a standard diet. All diets were administered ad libitum for 13 consecutive weeks. To examine stability of any potential effects, the administration period was followed by a 5-week recovery period, during which only the standard diet was provided to all animals. No significant, dose-related effects on body weight were found in rats fed a Leu- and Ile-supplemented diet. Val mixed into a diet at 5.0% (w/w) decreased slightly, but significantly body weight gain in females, but not males. Ile (5.0% w/w) affected the urine electrolytes, protein, ketone bodies, urine glucose, and urobilinogen in both genders, yet the observed changes remained mostly within the range observed in controls. The random findings in hepatology and ophthalmology at the 13-week sacrifice were not considered toxicologically relevant to effects of the tested amino acids. No significant changes in organ weights were recorded. We estimate the no-observed-adverse-effect level (NOAEL) for Ile at 2.5% for both genders (male, 1.565 +/- 0.060 g/kg/day; females, 1.646 +/- 0.095 g/kg/day), Val at 5.0% for males (3.225 +/- 0.135 g/kg/day) and 2.5% for females (1.853 +/- 0.060 g/kg/day), and Leu at 5.0% for both genders (males, 3.333 +/- 0.101 g/kg/day: females, 3.835 +/- 0.257 g/kg/day). PMID:15204732

Tsubuku, Shoji; Hatayama, Kazuhisa; Katsumata, Toyohisa; Nishimura, Nobuo; Mawatari, Kazunori; Smriga, Miro; Kimura, Takeshi

368

Direct thin layer chromatography enantioresolution of some basic dl-amino acids using a pharmaceutical industry waste as chiral impregnating reagent  

Microsoft Academic Search

Direct enantiomeric resolution of dl-arginine, dl-histidine, dl-lysine, dl-valine and dl-leucine into their enantiomers was achieved by thin layer chromatography (TLC) on silica gel plates impregnated with optically pure (1R, 3R, 5R)-2-azabicyclo[3,3,0]octan-3-carbo-xylic acid (0.011 M) as a chiral selector which is a waste of a pharmaceutical industry. Different combinations of acetonitrile-methanol-water were found to be successful in resolving the dl-amino acids.

R. Bhushan; J. Martens; G. Thuku Thiongo

2000-01-01

369

Amino acid uptake by Lemna gibba by a mechanism with affinity to neutral Land D-amino acids  

Microsoft Academic Search

Earlier work suggested that amino acid uptake by Lemna gibba cells is a H+-cotransport mechanism driven by a proton-electrochemical gradient at the plasmalemma. The present investigations of the transient membrane depolarizations elicited by amino acids and tracer-uptake experiments show that all neutral a-L-amino acids, D-alanine and analogues, like ß-alanine and p-fluorophenylalanine, are transported by the same system. It remains to

K.-D. Jung; U. Lüttge

1980-01-01

370

Amino acid fermentation at the origin of the genetic code  

PubMed Central

There is evidence that the genetic code was established prior to the existence of proteins, when metabolism was powered by ribozymes. Also, early proto-organisms had to rely on simple anaerobic bioenergetic processes. In this work I propose that amino acid fermentation powered metabolism in the RNA world, and that this was facilitated by proto-adapters, the precursors of the tRNAs. Amino acids were used as carbon sources rather than as catalytic or structural elements. In modern bacteria, amino acid fermentation is known as the Stickland reaction. This pathway involves two amino acids: the first undergoes oxidative deamination, and the second acts as an electron acceptor through reductive deamination. This redox reaction results in two keto acids that are employed to synthesise ATP via substrate-level phosphorylation. The Stickland reaction is the basic bioenergetic pathway of some bacteria of the genus Clostridium. Two other facts support Stickland fermentation in the RNA world. First, several Stickland amino acid pairs are synthesised in abiotic amino acid synthesis. This suggests that amino acids that could be used as an energy substrate were freely available. Second, anticodons that have complementary sequences often correspond to amino acids that form Stickland pairs. The main hypothesis of this paper is that pairs of complementary proto-adapters were assigned to Stickland amino acids pairs. There are signatures of this hypothesis in the genetic code. Furthermore, it is argued that the proto-adapters formed double strands that brought amino acid pairs into proximity to facilitate their mutual redox reaction, structurally constraining the anticodon pairs that are assigned to these amino acid pairs. Significance tests which randomise the code are performed to study the extent of the variability of the energetic (ATP) yield. Random assignments can lead to a substantial yield of ATP and maintain enough variability, thus selection can act and refine the assignments into a proto-code that optimises the energetic yield. Monte Carlo simulations are performed to evaluate the establishment of these simple proto-codes, based on amino acid substitutions and codon swapping. In all cases, donor amino acids are assigned to anticodons composed of U+G, and have low redundancy (1-2 codons), whereas acceptor amino acids are assigned to the the remaining codons. These bioenergetic and structural constraints allow for a metabolic role for amino acids before their co-option as catalyst cofactors. Reviewers: this article was reviewed by Prof. William Martin, Prof. Eörs Szathmáry (nominated by Dr. Gáspár Jékely) and Dr. Ádám Kun (nominated by Dr. Sandor Pongor)

2012-01-01

371

From one amino acid to another: tRNA-dependent amino acid biosynthesis  

PubMed Central

Aminoacyl-tRNAs (aa-tRNAs) are the essential substrates for translation. Most aa-tRNAs are formed by direct aminoacylation of tRNA catalyzed by aminoacyl-tRNA synthetases. However, a smaller number of aa-tRNAs (Asn-tRNA, Gln-tRNA, Cys-tRNA and Sec-tRNA) are made by synthesizing the amino acid on the tRNA by first attaching a non-cognate amino acid to the tRNA, which is then converted to the cognate one catalyzed by tRNA-dependent modifying enzymes. Asn-tRNA or Gln-tRNA formation in most prokaryotes requires amidation of Asp-tRNA or Glu-tRNA by amidotransferases that couple an amidase or an asparaginase to liberate ammonia with a tRNA-dependent kinase. Both archaeal and eukaryotic Sec-tRNA biosynthesis and Cys-tRNA synthesis in methanogens require O-phosophoseryl-tRNA formation. For tRNA-dependent Cys biosynthesis, O-phosphoseryl-tRNA synthetase directly attaches the amino acid to the tRNA which is then converted to Cys by Sep-tRNA: Cys-tRNA synthase. In Sec-tRNA synthesis, O-phosphoseryl-tRNA kinase phosphorylates Ser-tRNA to form the intermediate which is then modified to Sec-tRNA by Sep-tRNA:Sec-tRNA synthase. Complex formation between enzymes in the same pathway may protect the fidelity of protein synthesis. How these tRNA-dependent amino acid biosynthetic routes are integrated into overall metabolism may explain why they are still retained in so many organisms.

Sheppard, Kelly; Yuan, Jing; Hohn, Michael J.; Jester, Brian; Devine, Kevin M.; Soll, Dieter

2008-01-01

372

A Novel meso-Diaminopimelate Dehydrogenase from Symbiobacterium thermophilum: Overexpression, Characterization, and Potential for d-Amino Acid Synthesis  

PubMed Central

meso-Diaminopimelate dehydrogenase (meso-DAPDH) is an NADP+-dependent enzyme which catalyzes the reversible oxidative deamination on the d-configuration of meso-2,6-diaminopimelate to produce l-2-amino-6-oxopimelate. In this study, the gene encoding a meso-diaminopimelate dehydrogenase from Symbiobacterium thermophilum was cloned and expressed in Escherichia coli. In addition to the native substrate meso-2,6-diaminopimelate, the purified enzyme also showed activity toward d-alanine, d-valine, and d-lysine. This enzyme catalyzed the reductive amination of 2-keto acids such as pyruvic acid to generate d-amino acids in up to 99% conversion and 99% enantiomeric excess. Since meso-diaminopimelate dehydrogenases are known to be specific to meso-2,6-diaminopimelate, this is a unique wild-type meso-diaminopimelate dehydrogenase with a more relaxed substrate specificity and potential for d-amino acid synthesis. The enzyme is the most stable meso-diaminopimelate dehydrogenase reported to now. Two amino acid residues (F146 and M152) in the substrate binding sites of S. thermophilum meso-DAPDH different from the sequences of other known meso-DAPDHs were replaced with the conserved amino acids in other meso-DAPDHs, and assay of wild-type and mutant enzyme activities revealed that F146 and M152 are not critical in determining the enzyme's substrate specificity. The high thermostability and relaxed substrate profile of S. thermophilum meso-DAPDH warrant it as an excellent starting enzyme for creating effective d-amino acid dehydrogenases by protein engineering.

Gao, Xiuzhen; Chen, Xi; Liu, Weidong; Feng, Jinhui; Wu, Qiaqing; Hua, Ling

2012-01-01

373

Abc Amino Acids: Design, Synthesis, and Properties of New Photoelastic Amino Acids  

SciTech Connect

Photoisomerizable amino acids provide a direct avenue to the experimental manipulation of bioactive polypeptides, potentially allowing real-time, remote control of biological systems and enabling useful applications in nanobiotechnology. Herein, we report a new class of photoisomerizable amino acids intended to cause pronounced expansion and contraction in the polypeptide backbone, i.e., to be photoelastic. These compounds, termed Abc amino acids, employ a photoisomerizable azobiphenyl chromophore to control the relative disposition of aminomethyl and carboxyl substituents. Molecular modeling of nine Abc isomers led to the identification of one with particularly attractive properties, including the ability to induce contractions up to 13A in the backbone upon transa?cis photoisomerization. This isomer, designated mpAbc, has substituents at meta and para positions on the inner (azo-linked) and outer rings, respectively. An efficient synthesis of Fmoc-protected mpAbc was executed in which the biaryl components were formed via Suzuki couplings and the azo linkage was formed via amine/nitroso condensation; protected forms of three other Abc isomers were prepared similarly. A decapeptide incorporating mpAbc was synthesized by conventional solid-phase methods and displayed characteristic azobenzene photochemical behavior with optimal conversion to the cis isomer at 360 nm and a thermal cisa?trans half life of 100 min. at 80 AoC.

Standaert, Robert F [ORNL; Park, Dr Seung Bum [Seoul National University

2006-01-01

374

Two amino acid residues determine the low substrate affinity of human cationic amino acid transporter-2A.  

PubMed

Mammalian cationic amino acid transporters (CAT) differ in their substrate affinity and sensitivity to trans-stimulation. The apparent Km values for cationic amino acids and the sensitivity to trans-stimulation of CAT-1, -2B, and -3 are characteristic of system y+. In contrast, CAT-2A exhibits a 10-fold lower substrate affinity and is largely independent of substrate at the trans-side of the membrane. CAT-2A and -2B demonstrate such divergent transport properties, even though their amino acid sequences differ only in a stretch of 42 amino acids. Here, we identify two amino acid residues within this 42-amino acid domain of the human CAT-2A protein that are responsible for the apparent low affinity of both the extracellular and intracellular substrate-binding sites. These residues are located in the fourth intracellular loop, suggesting that they are not part of the translocation pathway. Rather, they may be responsible for the low affinity conformation of the substrate-binding sites. The sensitivity to trans-stimulation is not determined by the same amino acid residues as the substrate affinity and must involve a more complex interaction between individual amino acid residues. In addition to the 42-amino acid domain, the adjacent transmembrane domain X seems to be involved in this function. PMID:12637504

Habermeier, Alice; Wolf, Sabine; Martiné, Ursula; Gräf, Petra; Closs, Ellen I

2003-03-12

375

Amino acid composition and antioxidant capacity of Spanish honeys.  

PubMed

The amino acid composition of 53 honey samples from Spain, consisting of 39 floral, 5 honeydew, and 9 blend honeys, has been determined. Physicochemical characteristics, polyphenolic content, amino acid composition, and estimation of the radical scavenging capacity against the stable free radical DPPH of the honey samples were analyzed. The resulting data have been statistically evaluated. The results showed that pH, acidity, net absorbance, electrical conductivity, and total polyphenolic contents of the honeys showed a strong correlation with the radical scavenging capacity. The correlation between the radical scavenging capacity of honey and amino acid contents was high with 18 of the 20 amino acids detected, with correlation values higher than those obtained for polyphenolic content. These results suggest that the amino acid composition of honey is an indicator of the sample's scavenging capacity. PMID:17227066

Pérez, Rosa Ana; Iglesias, María Teresa; Pueyo, Encarnación; Gonzalez, Montserrat; de Lorenzo, Cristina

2007-01-24

376

Free amino acids in botanicals and botanical preparations.  

PubMed

Numerous studies were carried out about aminoacidic composition of vegetable proteins, but information about the free amino acid pool and the role of these substances is very incomplete. The aim of this paper was to contribute to the scarce knowledge concerning the composition of free amino acids in botanicals and botanical preparations widely used as food, in dietary supplements, and in pharmaceutical products. This work studied the composition of free amino acids, identified the major components of 19 species of plants, and evaluated the influence of different types of extraction on the amino acid profile. Amino acids were determined using an automatic precolumn derivatization with fluorenylmethyl-chloroformate and reversed-phase liquid chromatography with fluorescence and ultraviolet detection. The amounts of total free amino acids varied widely between plants, from approximately 12 g in 100 g of Echinacea pallida extract to less than 60 mg in the same amount of Coleus forskohlii, Garcinia cambogia, and Glycine max. In 13 plants arginine, asparagine, glutamine, proline, and gamma-aminobutyric acid were the free amino acids found in preponderant quantities. The levels of free amino acids above the quantification limit in 36 assayed samples of botanicals, extracts, and supplements are shown. PMID:18576976

Carratù, B; Boniglia, C; Giammarioli, S; Mosca, M; Sanzini, E

2008-06-01

377

Survival of Amino Acids in Micrometeorites During Atmospheric Entry  

NASA Astrophysics Data System (ADS)

The delivery of amino acids by micrometeorites to the early Earth during the period of heavy bombardment could have been a significant source of the Earth's prebiotic amino acid inventory provided that these organic compounds survived atmospheric entry heating. To investigate the sublimation of amino acids from a micrometeorite analog at elevated temperature, grains from the CM-type carbonaceous chondrite Murchison were heated to 550°C inside a glass sublimation apparatus (SA) under reduced pressure. The sublimed residue that had collected on the cold finger of the SA after heating was analyzed for amino acids by HPLC. We found that when the temperature of the meteorite reached ~150°C, a large fraction of the amino acid glycine had vaporized from the meteorite, recondensed onto the end of the SA cold finger, and survived as the rest of the grains heated to 550°C. ?-Aminoisobutryic acid and isovaline, which are two of the most abundant non-protein amino acids in Murchison, did not sublime from the meteorite and were completely destroyed during the heating experiment. Our experimental results suggest that sublimation of glycine present in micrometeorite grains may provide a way for this amino acid to survive atmospheric entry heating at temperatures >550°C; all other amino acids apparently are destroyed.

Glavin, Daniel P.; Bada, Jeffrey L.

2001-09-01

378

Deleting valine-125 and cysteine-126 in glycoprotein gI of pseudorabies virus strain NIA-3 decreases plaque size and reduces virulence in mice  

Microsoft Academic Search

Summary We investigated the function of antigenic domains on gI in virulence and immunogenicity. Three PRV gI mutants were constructed by deleting nucleotides coding for the following amino acids: valine-125 and cysteine-126, located in a discontinuous antigenic domain (M 303); glycine-59 and aspartic acid-60 located in a continuous antigenic domain (M 304); and arginine-67 and alanine-68, located in a discontinuous

Liesbeth Jacobs; H. J. Rziha; T. G. Kimman; A. L. J. Gielkens; J. T. Van Oirschot

1993-01-01

379

Gas-phase Acidities of Aspartic Acid, Glutamic Acid, and their Amino Acid Amides.  

SciTech Connect

Gas-phase acidities (GA or ?Gacid) for the two most acidic common amino acids, aspartic acid and glutamic acid, have been determined for the first time. Because of the amide linkage’s importance in peptides and as an aid in studying side chain versus main chain deprotonation, aspartic acid amide and glutamic acid amide were also studied. Experimental GA values were measured by proton transfer reactions in an electrospray ionization/Fourier transform ion cyclotron resonance mass spectrometer. Calculated GAs were obtained by density functional and molecular orbital theory approaches. The best agreement with experiment was found at the G3MP2 level; the MP2/CBS and B3LYP/aug-cc-pVDZ results are 3–4 kcal/mol more acidic than the G3MP2 results. Experiment shows that aspartic acid is more acidic than glutamic acid by ca. 3 kcal/mol whereas the G3MP2 results show a smaller acidity difference of 0.2 kcal/mol. Similarly, aspartic acid amide is experimentally observed to be ca. 2 kcal/mol more acidic than glutamic acid amide whereas the G3MP2 results show a correspondingly smaller energy difference of 0.7 kcal/mol. The computational results clearly show that the anions are all ring-like structures with strong hydrogen bonds between the OH or NH2 groups and the CO2? group from which the proton is removed. The two amino acids are main-chain deprotonated. In addition, use of the COSMO model for the prediction of the free energy differences in aqueous solution gave values in excellent agreement with the most recent experimental values for pKa. Glutamic acid is predicted to be more acidic than aspartic acid in aqueous solution due to differential solvation effects.

Li, Zhong; Matus, Myrna H.; Velazquez, Hector A.; Dixon, David A.; Cassady, Carolyn J.

2007-02-14

380

Mechanistic Pathways of Formation of Acrylamide from Different Amino Acids  

Microsoft Academic Search

Studies on model systems of amino acids and sugars have indicated that acrylamide can be generated from asparagine or from amino acids that can produce acrylic acid either directly such as ?-alanine, aspartic acid and carnosine or indirectly such as cysteine and serine. The main pathway specifically involves asparagine and produces acrylamide directly after a sugar-assisted decarboxylation and 1,2-elimination steps

Varoujan A. Yaylayan; Carolina Perez Locas; Andrzej Wnorowski; John O’Brien

381

Thin-Layer Chromatography of Dansyl Amino Acids on Polyamide  

Microsoft Academic Search

Summary Thin-Layer Chromatography of Dansyl Amino Acids on Polyamide A two-dimensional thin-layer chromatography system for the separation of the dansyl derivatives of the amino acids commonly found in proteins is described. Chromatography was performed on polyamide sheets using water-pyridine-formic acid (93:3.5:3.5 v\\/v) and benzene-acetic acid (4.5:1 v\\/v) as the solvents.

James C. Wesenberg; R. J. Thibert

1977-01-01

382

Molecular regulation of amino acid biosynthesis in plants  

Microsoft Academic Search

Our understanding of amino acid biosynthesis in plants has grown by leaps and bounds in the last decade. It appears that most of the amino acid biosynthesis takes place in the chloroplast. Recent demonstration of glutamine synthetase and DAHP synthase in the vascular tisuue has added a new dimension in the complexity of the nitrogen cycle in plants. Isolation of

B. K. Singh; B. F. Matthews

1994-01-01

383

Clearance of amino acids by hemodialysis in argininosuccinate synthetase deficiency  

Microsoft Academic Search

We determined the dialytic clearance of amino acids involved in ammoniagenesis and nitrogen excretion in a neonate with argininosuccinate synthetase deficiency who underwent acute hemodialysis. Plasma ammonia and plasma and dialysate amino acid concentrations were obtained at baseline, 30-minute intervals during hemodialysis, and 30 minutes after the completion of hemodialysis. Plasma ammonia concentrations declined by 56% during the 90-minute hemodialysis

Kevin D. McBryde; Timothy L. Kudelka; David B. Kershaw; Patrick D. Brophy; John J. Gardner; William E. Smoyer

2004-01-01

384

Amino Acid Metabolism in the Griseofulvin Producer 'Pen. nigricans Thom'.  

National Technical Information Service (NTIS)

A total of 18 amino acids were detected in the mycelium of P. nigricans. Predominant among these were glutamic acid (38.9 mg per gram of dry mycelium), proline (30.15 mg), and histidine (28.42 mg). In addition a high content of the amino sugar glucosamine...

T. P. Efimova

1974-01-01

385

?-Vinylic amino acids: occurrence, asymmetric synthesis, and biochemical mechanisms  

Microsoft Academic Search

This report presents an overview of the family of naturally occurring ‘vinylic’ amino acids, namely those that feature a C–C double bond directly attached to the ?-carbon, along the side chain. Strategies that have been brought to bear on the stereocontrolled synthesis of these olefinic amino acids are surveyed. The mechanistic diversity by which such ‘vinylic triggers’ can be actuated

David B. Berkowitz; Bradley D. Charette; Kannan R. Karukurichi; Jill M. McFadden

2006-01-01

386

Two types of amino acid substitutions in protein evolution  

Microsoft Academic Search

Summary The frequency of amino acid substitutions, relative to the frequency expected by chance, decreases linearly with the increase in physico-chemical differences between amino acid pairs involved in a substitution. This correlation does not apply to abnormal human hemoglobins. Since abnormal hemoglobins mostly reflect the process of mutation rather than selection, the correlation manifest during protein evolution between substitution frequency

Takashi Miyata; Sanzo Miyazawa; Teruo Yasunaga

1979-01-01

387

The Amino Acid Composition of the Sutter's Mill Carbonaceous Chondrite  

NASA Astrophysics Data System (ADS)

We analyzed the amino acid composition of a fragment of the Sutter's Mill meteorite (SM2) using liquid chromatography time of flight mass spectrometry. In contrast to other CM meteorites, only trace levels of amino acids were detected in SM2.

Glavin, D. P.; Burton, A. S.; Elsila, J. E.; Dworkin, J. P.; Yin, Q.-Z.; Cooper, G.; Jenniskens, P.

2012-09-01

388

Factors Affecting Circadian Periodicity of Blood Amino Acids in Man.  

National Technical Information Service (NTIS)

Total whole blood amino acids in normal men and all major individual blood amino acids (with the single exception of citrulline) were found to display a circadian periodicity characterized by peak values between 1200 and 2000 hours and lowest values betwe...

R. D. Feigin A. S. Klainer W. R. Beisel

1968-01-01

389

The Amino Acid Sequence of beta Galactosidase of Escherichia coli  

Microsoft Academic Search

The amino acid sequence of beta -galactosidase was determined. The protein contains 1021 amino acid residues in a single polypeptide chain. The subunit molecular weight calculated from the sequence is 116,248. The sequence determination, carried out mainly by conventional methods, was aided by complementation tests, by the use of termination mutant strains, and by a new immunochemical method. The five

Audree V. Fowler; Irving Zabin

1977-01-01

390

Biological activity of amino acids in organotypic tissue cultures.  

PubMed

We studied the effect of 20 standard L-amino acids on proliferation of the nervous, cardiovascular, urogenital, digestive, and immune system tissues from young and old animals in organotypic cultures. The effect of amino acids on tissue culture proliferation depended on their origin and animal age. PMID:24143390

Chalisova, N I; Kontsevaya, N E; Linkova, N S; Pronyaeva, V E; Chervyakova, N A; Umnov, R S; Benberin, V V; Khavinson, V H

2013-07-01

391

EFFECT OF LEAD ON GAMMA AMINO BUTYRIC ACID SYNTHESIS  

EPA Science Inventory

The project studies the inhibitory effect of lead on the enzymatic activity of brain glutamic amino acid decarboxylase (GADC). The enzyme is responsible for the catalytic formation of gamma amino butyric acid (GABA) inhibitory neurons which is believed to be involved with the tra...

392

Synthesis and Characterization of Novel Bi and Tricyclic ?-Amino Acids  

Microsoft Academic Search

As part of a medicinal chemistry collaboration, a number of novel bi- and tricyclic ?-amino acids were prepared through various routes and characterized by H nuclear Overhauser effect difference experiments. The syntheses provide a number of routes to access some highly substituted amino acid derivatives that have not been reported previously. It is envisaged that the chemistry described here could

Matthew R. Johnson; Jolicia F. Gauuan; Cheng Guo; Peter R. Guzzo; Van-Duc Le; Rajesh A. Shenoy; James Hamby; Howard Roark; Michael Stier; John E. Mangette

2011-01-01

393

Conserved amino acid markers from past influenza pandemic strains  

Microsoft Academic Search

BACKGROUND: Finding the amino acid mutations that affect the severity of influenza infections remains an open and challenging problem. Of special interest is better understanding how current circulating influenza strains could evolve into a new pandemic strain. Influenza proteomes from distinct viral phenotype classes were searched for class specific amino acid mutations conserved in past pandemics, using reverse engineered linear

Jonathan E Allen; Shea N Gardner; Elizabeth A Vitalis; Tom R Slezak

2009-01-01

394

Single amino acid replacements affecting the thermostability of kanamycin nucleotidyltransferase  

Microsoft Academic Search

Amino acid residues of the carboxyl-terminal region of kanamycin nucleotidyltransferase were modified using segment-directed mutagenesis. Six different mutant enzymes with single amino acid replacements were selected out of 59 clones by DNA sequence analyses. The mutant enzymes were purified and it was found that the thermostability of one mutant enzyme was identical to the wild type, whereas the other five

Masazumi Matsumura; Shiro Kataoka; Shuichi Aiba

1986-01-01

395

Boron containing amino acid compounds and methods for their use  

SciTech Connect

The present invention provides new boron containing amino acid compounds and methods for making these compounds by contacting melphalan or another nitrogen mustard derivative and sodium borocaptate. The present invention also provides a method of treating a mammal having a tumor by administering to the mammal a therapeutically effective amount of the new boron containing amino acid compounds.

Glass, J.D.; Coderre, J.A.

2000-01-25

396

The amino acid sequence of snapping turtle (Chelydra serpentina) ribonuclease  

Microsoft Academic Search

Snapping turtle (Chelydra serpentina) ribonuclease was isolated from pancreatic tissue. Turtle ribonuclease binds much more weakly to the affinity chromatography matrix used than mammalian ribonucleases. The amino acid sequence was determined from overlapping peptides obtained from three different digests. The N-terminal amino acid sequence of the protein determined by others and homology were used as additional evidence for several overlaps.

Cornelis Schüller; Jaap J. Beintema; Jaap Broos; Janneke Meulenberg

1985-01-01

397

Highly enantioselective synthesis of a fluorescent amino acid  

Microsoft Academic Search

A high enantiomeric excess (>99.5%) synthesis of l-2-amino-3-(7-methoxy-4-coumaryl) propionic acid (l-Amp) is described. The two step synthesis route of this non-proteinogenic amino acid includes an oxazinone derivative as glycine enolate, which is alkylated with the fluorogenic group.

Péter Kele; Guodong Sui; Qun Huo; Roger M. Leblanc

2000-01-01

398

Genetic code correlations: Amino acids and their anticodon nucleotides  

Microsoft Academic Search

Summary The data here show direct correlations between both the hydrophobicity and the hydrophilicity of the homocodonic amino acids and their anticodon nucleotides. While the differences between properties of uracil and cytosine derivatives are small, further data show that uracil has an affinity for charged species. Although these data suggest that molecular relationships between amino acids and anticodons were responsible

A. L. Weber; J. C. Lacey

1978-01-01

399

Subcritical water extraction of amino acids from Atacama Desert soils  

Microsoft Academic Search

(1) Amino acids are considered organic molecular indicators in the search for extant and extinct life in the Solar System. Extraction of these molecules from a particulate solid matrix, such as Martian regolith, will be critical to their in situ detection and analysis. The goals of this study were to optimize a laboratory amino acid extraction protocol by quantitatively measuring

Xenia Amashukeli; Christine C. Pelletier; James P. Kirby; Frank J. Grunthaner

2007-01-01

400

Subcritical water extraction of amino acids from Atacama Desert soils  

Microsoft Academic Search

Amino acids are considered organic molecular indicators in the search for extant and extinct life in the Solar System. Extraction of these molecules from a particulate solid matrix, such as Martian regolith, will be critical to their in situ detection and analysis. The goals of this study were to optimize a laboratory amino acid extraction protocol by quantitatively measuring the

Xenia Amashukeli; Christine C. Pelletier; James P. Kirby; Frank J. Grunthaner

2007-01-01

401

Amino acid metabolism in nongrowing environments in higher plants  

Microsoft Academic Search

During winter season, growth of biennial and perennial plants was virtually halted. Amino acid analyses of 74 samples of woody and herbaceous plants including grasses and winter wheat showed following results. In innately dormant plants, synthesis and accumulation of free amino acids were completed in fall and next changes occurred in the following spring. In plants under enforced dormancy, a

S. Sagisaka

1993-01-01

402

Evolutionary patterns of amino acid substitutions in 12 Drosophila genomes  

Microsoft Academic Search

BACKGROUND: Harnessing vast amounts of genomic data in phylogenetic context stemming from massive sequencing of multiple closely related genomes requires new tools and approaches. We present a tool for the genome-wide analysis of frequencies and patterns of amino acid substitutions in multiple alignments of genes’ coding regions, and a database of amino acid substitutions in the phylogeny of 12 Drosophila

Lev Y Yampolsky; Michael A Bouzinier

2010-01-01

403

Parenteral sulfur amino acid requirements in septic infants  

Technology Transfer Automated Retrieval System (TEKTRAN)

To investigate parenteral methionine requirements of critically ill, septic infants, we conducted an investigation involving 12 infants (age 2+/-1 years; weight 13+/-2kg) using the intravenous indicator amino acid oxidation and balance technique. They received a balanced parenteral amino acid formul...

404

Parenteral amino acid intakes in critically ill children  

Technology Transfer Automated Retrieval System (TEKTRAN)

Parenteral amino acid formulas used in parenteral nutrition have a variable composition. To determine the amino acid intake of parenterally fed, critically ill children, and compare it with recommended dietary allowances (RDA) established by the Institute of Medicine (IOM), we retrospectively review...

405

A modular synthesis of dithiocarbamate pendant unnatural ?-amino acids.  

PubMed

Unnatural ?-amino acids containing dithiocarbamate side chains were synthesized by a one-pot reaction of in situ generated dithiocarbamate anions with sulfamidates. A wide range of these anions participated in the highly regio- and stereo-selective ring opening of sulfamidates to produce the corresponding dithiocarbamate pendant ?-amino acids in high yields. PMID:22814637

Saha, Amit; Baig, R B Nasir; Leazer, John; Varma, Rajender S

2012-07-20

406

Substrate specificity of the amino acid transporter PAT1.  

PubMed

The proton coupled amino acid transporter PAT1 expressed in intestine, brain, and other organs accepts L- and D-proline, glycine, and L-alanine but also pharmaceutically active amino acid derivatives such as 3-amino-1-propanesulfonic acid, L-azetidine-2-carboxylic acid, and cis-4-hydroxy-D-proline as substrates. We systematically analyzed the structural requirements for PAT1 substrates by testing 87 amino acids, proline homologs, indoles, and derivatives. Affinity data and effects on membrane potential were determined using Caco-2 cells. For aliphatic amino acids, a blocked carboxyl group, the distance between amino and carboxyl group, and the position of the hydroxyl group are affinity limiting factors. Methylation of the amino group enhances substrate affinity. Hetero atoms in the proline template are well tolerated. Aromatic alpha-amino acids display low affinity. PAT1 interacts strongly with heterocyclic aromatic acids containing an indole scaffold. The structural requirements of PAT1 substrates elucidated in this study will be useful for the development of prodrugs. PMID:16699824

Metzner, L; Neubert, K; Brandsch, M

2006-05-15

407

Boron containing amino acid compounds and methods for their use  

DOEpatents

The present invention provides new boron containing amino acid compounds and methods for making these compounds by contacting melphalan or another nitrogen mustard derivative and sodium borocaptate. The present invention also provides a method of treating a mammal having a tumor by administering to the mammal a therapeutically effective amount of the new boron containing amino acid compounds.

Glass, John D. (Shoreham, NY); Coderre, Jeffrey A. (Wading River, NY)

2000-01-01

408

Renal handling of amino acids in 5\\/6-nephrectomized rats: Stimulation of renal amino acid reabsorption after treatment with triiodothyronine or dexamethasone under amino acid load  

Microsoft Academic Search

Summary In anaesthetized adult female rats, the renal amino acid handling was measured six days after 5\\/6 nephrectomy (5\\/6NX). The distinct rise in blood urea nitrogen as well as the significant reduction in urine flow and GFR indicate an impairment of kidney function. In principle, in 5\\/6NX rats amino acid plasma concentrations were comparable to those of control animals with

Ch. Fleck; K. Gräfe; I. Kart

1999-01-01

409

Dietary sulfur amino acid modulation of cysteine sulfinic acid decarboxylase.  

PubMed

Male rats were fed sulfur and nonsulfur amino acid-supplemented diets, and the response of cysteine sulfinic acid decarboxylase (CSAD) activity was determined. After adaptation to a casein-based basal diet, rats were fed diets containing additions of L-methionine. Hepatic CSAD activity decreased in a dose-dependent manner. Significant depression of CSAD activity in liver was evident within 24 h of feeding rats a methionine-supplemented diet. Depression of enzyme activity was reversed upon refeeding the basal diet. After rats were fed diets supplemented with methionine, cystine, homocystine, S-methyl-L-cysteine, phenylalanine, leucine, or ethionine for 14 days, hepatic CSAD activity in rats fed S-methyl-L-cysteine-, phenylalanine-, or leucine-supplemented diets was not depressed compared with activity in rats fed a basal diet. In contrast, CSAD activity in livers of rats fed cystine-, homocystine-, methionine-, or ethionine-supplemented diets was 60, 40, 40, and 8%, respectively, of the activity in livers from control rats. Immunochemical detection and quantification of CSAD protein in rat liver indicated that CSAD protein concentration was correlated to CSAD activity. CSAD activity may be specifically regulated by sulfur amino acids metabolized by the S-adenosylmethionine-dependent pathway of methionine metabolism. PMID:1951678

Jerkins, A A; Steele, R D

1991-11-01

410

Arabidopsis Branched-Chain Aminotransferase 3 Functions in Both Amino Acid and Glucosinolate Biosynthesis1[W][OA  

PubMed Central

In Arabidopsis thaliana, transamination steps in the leucine biosynthetic and catabolic pathways and the methionine (Met) chain elongation cycle of aliphatic glucosinolate formation are catalyzed by branched-chain aminotransferases (BCATs) that are encoded by a small gene family of six members. One member of this family, the plastid-located BCAT3, was shown to participate in both amino acid and glucosinolate metabolism. In vitro activity tests with the recombinant protein identified highest activities with the 2-oxo acids of leucine, isoleucine, and valine, but also revealed substantial conversion of intermediates of the Met chain elongation pathway. Metabolite profiling of bcat3-1 single and bcat3-1/bcat4-2 double knockout mutants showed significant alterations in the profiles of both amino acids and glucosinolates. The changes in glucosinolate proportions suggest that BCAT3 most likely catalyzes the terminal steps in the chain elongation process leading to short-chain glucosinolates: the conversion of 5-methylthiopentyl-2-oxo and 6-methylthiohexyl-2-oxo acids to their respective Met derivatives, homomethionine and dihomo-methionine, respectively. The enzyme can also at least partially compensate for the loss of BCAT4, which catalyzes the initial step of Met chain elongation by converting Met to 4-methylthio-2-oxobutanoate. Our results show the interdependence of amino acid and glucosinolate metabolism and demonstrate that a single enzyme plays a role in both processes.

Knill, Tanja; Schuster, Joachim; Reichelt, Michael; Gershenzon, Jonathan; Binder, Stefan

2008-01-01

411

Urinary amino acid analysis: a comparison of iTRAQ-LC-MS/MS, GC-MS, and amino acid analyzer.  

PubMed

Urinary amino acid analysis is typically done by cation-exchange chromatography followed by post-column derivatization with ninhydrin and UV detection. This method lacks throughput and specificity. Two recently introduced stable isotope ratio mass spectrometric methods promise to overcome those shortcomings. Using two blinded sets of urine replicates and a certified amino acid standard, we compared the precision and accuracy of gas chromatography/mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) of propyl chloroformate and iTRAQ derivatized amino acids, respectively, to conventional amino acid analysis. The GC-MS method builds on the direct derivatization of amino acids in diluted urine with propyl chloroformate, GC separation and mass spectrometric quantification of derivatives using stable isotope labeled standards. The LC-MS/MS method requires prior urinary protein precipitation followed by labeling of urinary and standard amino acids with iTRAQ tags containing different cleavable reporter ions distinguishable by MS/MS fragmentation. Means and standard deviations of percent technical error (%TE) computed for 20 amino acids determined by amino acid analyzer, GC-MS, and iTRAQ-LC-MS/MS analyses of 33 duplicate and triplicate urine specimens were 7.27+/-5.22, 21.18+/-10.94, and 18.34+/-14.67, respectively. Corresponding values for 13 amino acids determined in a second batch of 144 urine specimens measured in duplicate or triplicate were 8.39+/-5.35, 6.23+/-3.84, and 35.37+/-29.42. Both GC-MS and iTRAQ-LC-MS/MS are suited for high-throughput amino acid analysis, with the former offering at present higher reproducibility and completely automated sample pretreatment, while the latter covers more amino acids and related amines. PMID:19481989

Kaspar, Hannelore; Dettmer, Katja; Chan, Queenie; Daniels, Scott; Nimkar, Subodh; Daviglus, Martha L; Stamler, Jeremiah; Elliott, Paul; Oefner, Peter J

2009-05-15

412

Synthesis of amino acids by arc-discharge experiments  

NASA Astrophysics Data System (ADS)

Discharge was performed against ammonia water using a graphite rod as the anode and a silver thread as the cathode under an Ar atmosphere. HPLC and thin layer chromatograph (TLC) analyses showed that three kinds of amino acids were produced in the reaction mixture. As the graphite anode is the solitary source of carbon in the system, it is considered that amino acids have been produced by synthetic reaction between graphite and ammonia water. Thus, our results provide a possible way of formation of amino acids from elemental carbon on the primitive earth. In addition, the mechanism for the production of amino acids is discussed and the yields of different amino acids are presented.

Huaibin, S.; Chunlin, S.; Zengliang, Y.

2001-10-01

413

Peptide and amino acid separation with nanofiltration membranes  

SciTech Connect

Several nanofiltration membranes [UTC-20, 60 (Toray Industries), NF-40 (Film-Tech Corporation), Desal-5, G-20 (Desalination Systems), and NTR-7450 (Nitto Electric Industrial Co.)] were applied to separate amino acids and peptides on the basis of charge interaction with the membranes since most of them contain charged functional groups. Nanofiltration membranes having a molecular weight cutoff (MWCO) below 300 (UTC-20, 60, NF-40 and Desal-5) were not suitable for separation of amino acids. On the other hand, separation of amino acids and peptides with nanofiltration membranes having a MWCO around 2000-3000 (NTR-7450 and G-20) was satisfactory based on a charge effect mechanism; charged amino acids and peptides were rejected while neutral amino acids and peptides permeated through the membranes. Separation of peptides having different isoelectric points with nanofiltration membranes was possible by adjusting the pH. 15 refs., 11 figs., 4 tabs.

Tsuru, Toshinori; Shutou, Takatoshi; Nakao, Shin-Ichi; Kimura, Shoji (Univ. of Tokyo (Japan))

1994-05-01

414

Genetically encoding unnatural amino acids for cellular and neuronal studies  

PubMed Central

Proteins participate in various biological processes and can be harnessed to probe and control biological events selectively and reproducibly, but the genetic code limits the building block to 20 common amino acids for protein manipulation in living cells. The genetic encoding of unnatural amino acids will remove this restriction and enable new chemical and physical properties to be precisely introduced into proteins. Here we present new strategies for generating orthogonal tRNA-synthetase pairs, which made possible the genetic encoding of diverse unnatural amino acids in different mammalian cells and primary neurons. Using this new methodology, we incorporated unnatural amino acids with extended side chains into the K+ channel Kv1.4, and found that the bulkiness of residues in the inactivation peptide is essential for fast channel inactivation, a finding that had not been possible using conventional mutagenesis. This technique will stimulate and facilitate new molecular studies using tailored unnatural amino acids for cell biology and neurobiology.

Wang, Wenyuan; Takimoto, Jeffrey K; Louie, Gordon V; Baiga, Thomas J; Noel, Joseph P; Lee, Kuo-Fen; Slesinger, Paul A; Wang, Lei

2009-01-01

415

Amino Acid Catabolism and Malic Enzyme in Differentiating Dictyostelium discoideum  

PubMed Central

Amino acids produced from protein degradation are the major energy source for differentiation and aging in Dictyostelium discoideum. Considering the reactions involved in the conversion of amino acids from an average protein into tricarboxylic acid cycle intermediates, a route from a cycle intermediate (probably malate) to acetyl coenzyme A is required for the complete utilization of amino acids. Citrate was isolated from cells pulse-labeled with 14C-labeled amino acids and was cleaved with citrate lyase. When cells were pulse-labeled with [U-14C]-glutamate the specific radioactivity of the acetate and oxaloacetate portions of citrate were consistent with the conclusion that one-third of the carbon flowing through the tricarboxylic acid cycle is removed for the synthesis of acetyl coenzyme A. The data were also consistent with the patterns of carbon flux required to maintain steady-state levels of cycle intermediates in cells catabolizing amino acids. It is suggested that the malic enzyme (EC 1.1.1.40) catalyzes the synthesis of acetyl coenzyme A from malate and is responsible for the observed citrate labeling pattern. In cell extracts the activity of this enzyme increased markedly with the onset of differentiation. The properties of partially purified (40-fold) malic enzyme isolated at culmination indicated that the enzyme was allosteric and was positively affected by aspartate and glutamate. Thus, amino acid production from protein degradation would stimulate a reaction essential for the efficient utilization of these amino acids for energy.

Kelleher, Joanne K.; Kelly, Patrick J.; Wright, Barbara E.

1979-01-01

416

Soil Bacteria Take Up D-Amino Acids, Protect Plants  

NASA Astrophysics Data System (ADS)

Recently, many groups reported D-amino acid uptake by plant roots, raising the question of whether soil D-amino acids represent a source of nitrogen or a source of toxicity. The discussion needs to be placed in the context of competition with rhizosphere bacteria. To provide this context, we followed the concentrations of D- and L-enantiomers of alanine, glutamic acid, aspartic acid, and leucine after they were added to soils in the laboratory. In all cases, the uptake of L-enantiomer began immediately and proceeded rapidly until exhausted. In contrast, the uptake of D-enantiomer required induction: an initial period of inactivity followed by rapid consumption comparable in rate to L-enantiomer. The induced nature of the D activity was confirmed by the addition of rifampicin, an mRNA synthesis inhibitor. Preventing the synthesis of new enzymes abolished soil flora's ability to consume D-amino acids, but not L-amino acids. These results suggest that inducible special racemase enzymes, which can convert D-amino acids back to their native L-forms, are widespread among soil microorganisms. This finding does not rule out the possibility that some plants may out-compete microorganisms and be able to access D-amino acids. It does suggest, however, that rhizosphere bacteria can shield plants from the toxic effect of D-amino acids.

Sun, H. J.; Zhang, G.

2011-12-01

417

Wet, Carbonaceous Asteroids: Altering Minerals, Changing Amino Acids  

NASA Astrophysics Data System (ADS)

Many carbonaceous chondrites contain alteration products from water-rock interactions at low temperature and organic compounds. A fascinating fact known for decades is the presence in some of them of an assortment of organic compounds, including amino acids, sometimes called the building blocks of life. Murchison and other CM carbonaceous chondrites contain hundreds of amino acids. Early measurements indicated that the amino acids in carbonaceous chondrites had equal proportions of L- and D-structures, a situation called racemic. This was in sharp contrast to life on Earth, which heavily favors L- forms. However, beginning in 1997, John Cronin and Sandra Pizzarello (Arizona State University) found L- excesses in isovaline and several other amino acids in the Murchison carbonaceous chondrite. In 2009, Daniel Glavin and Jason Dworkin (Astrobiology Analytical Lab, Goddard Space Flight Center) reported the first independent confirmation of L-isovaline excesses in Murchison using a different analytical technique than employed by Cronin and Pizzarello. Inspired by this work, Daniel Glavin, Michael Callahan, Jason Dworkin, and Jamie Elsila (Astrobiology Analytical Lab, Goddard Space Flight Center), have done an extensive study of the abundance and symmetry of amino acids in carbonaceous chondrites that experienced a range of alteration by water in their parent asteroids. The results show that amino acids are more abundant in the less altered meteorites, implying that aqueous processing changes the mix of amino acids. They also confirmed the enrichment in L-structures of some amino acids, especially isovaline, confirming earlier work. The authors suggest that aqueously-altered planetesimals might have seeded the early Earth with nonracemic amino acids, perhaps explaining why life from microorganisms to people use only L- forms to make proteins. The initial imbalance caused by non-biologic processes in wet asteroids might have been amplified by life on Earth. Alternatively, the same processes that produced the L-amino acid excesses in carbonaceous asteroids also operated on the early Earth.

Taylor, G. J.

2011-04-01

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