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1

Influence of valine and other amino acids on total diacetyl and 2,3-pentanedione levels during fermentation of brewer's wort.  

PubMed

Undesirable butter-tasting vicinal diketones are produced as by-products of valine and isoleucine biosynthesis during wort fermentation. One promising method of decreasing diacetyl production is through control of wort valine content since valine is involved in feedback inhibition of enzymes controlling the formation of diacetyl precursors. Here, the influence of valine supplementation, wort amino acid profile and free amino nitrogen content on diacetyl formation during wort fermentation with the lager yeast Saccharomyces pastorianus was investigated. Valine supplementation (100 to 300 mg L(-1)) resulted in decreased maximum diacetyl concentrations (up to 37 % lower) and diacetyl concentrations at the end of fermentation (up to 33 % lower) in all trials. Composition of the amino acid spectrum of the wort also had an impact on diacetyl and 2,3-pentanedione production during fermentation. No direct correlation between the wort amino acid concentrations and diacetyl production was found, but rather a negative correlation between the uptake rate of valine (and also other branched-chain amino acids) and diacetyl production. Fermentation performance and yeast growth were unaffected by supplementations. Amino acid addition had a minor effect on higher alcohol and ester composition, suggesting that high levels of supplementation could affect the flavour profile of the beer. Modifying amino acid profile of wort, especially with respect to valine and the other branched-chain amino acids, may be an effective way of decreasing the amount of diacetyl formed during fermentation. PMID:23677441

Krogerus, Kristoffer; Gibson, Brian R

2013-08-01

2

Racemic synthesis and solid phase peptide synthesis application of the chimeric valine/leucine derivative 2-amino-3,3,4-trimethyl-pentanoic acid.  

PubMed

The synthesis of non natural amino acid 2-amino-3,3,4-trimethyl-pentanoic acid (Ipv) ready for solid phase peptide synthesis has been developed. Copper (I) chloride Michael addition, followed by a Curtius rearrangement are the key steps for the lpv synthesis. The racemic valine/leucine chimeric amino acid was then successfully inserted in position 5 of neuropeptide S (NPS) and the diastereomeric mixture separated by reverse phase HPLC. The two diastereomeric NPS derivatives were tested for intracellular calcium mobilization using HEK293 cells stably expressing the mouse NPS receptor where they behaved as partial agonist and pure antagonist. PMID:25073393

Pelà, M; Del Zoppo, L; Allegri, L; Marzola, E; Ruzza, C; Calo, G; Perissutti, E; Frecentese, F; Salvadori, S; Guerrini, R

2014-07-01

3

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. PMID:22537596

2012-01-01

4

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.

5

Thermal, dielectric studies on pure and amino acid ( L-glutamic acid, L-histidine, L-valine) doped KDP single crystals  

NASA Astrophysics Data System (ADS)

Amino acids ( L-glutamic acid, L-histidine, L-valine) doped potassium dihydrogen phospate crystals are grown by 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 mol% to 10 mol%. The solubility data for all dopants concentration were determined. There is variation in pH value and hence, there is habit modification of the grown crystals were characterized with UV-VIS, FT-IR studies, SHG trace elements and dielectric studies reveal slight distortion of lattice parameter for the heavily doped KDP crystals. UV-Visible spectra confirm the improvement in the transparency of these crystals on doping metal ions. FT-IR spectra reveal strong absorption band between 1400 and 1600 cm -1 for metal ion doped crystals. TGA-DTA studies reveal good thermal stability. The dopants increase the hardness value of the material and it 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.; Moorthy Babu, S.; Anbarasan, P. M.

2008-05-01

6

Response of piglets to the valine content in diet in combination with the supply of other branched-chain amino acids.  

PubMed

The branched-chain amino acids (BCAA) valine (Val) and isoleucine (Ile) are considered to be among the next-limiting amino acids for growth in piglets. In earlier studies, we estimated the standardized ileal digestible (SID) Val : Lys (lysine) requirement to be at least 70%, whereas the Ile : Lys requirement may be as low as 50%. Because the BCAA partially share a common route of catabolism, the supply of one BCAA may affect the availability of the other BCAA. Four experiments were conducted to determine the response of 6-week-old piglets to the Val supply in relation to the other BCAA. A deficient supply of Val or Ile typically results in a reduction in average daily feed intake (ADFI). Experiment 1 was designed to determine the effect of a limiting Val supply, independent of the effect on feed intake. In a dose-response study using restrictively fed piglets, nitrogen retention did not increase for an SID Val : Lys supply greater than 64%. In the remaining experiments, piglets were offered feed ad libitum using ADFI, average daily gain (ADG) and gain-to-feed ratio as response criteria. The interaction between the Val and leucine (Leu) was studied in Experiment 2 in a 2 × 2 factorial design (60% and 70% SID Val : Lys, and 111% and 165% SID Leu : Lys). Performance was considerably lower in piglets receiving 60% Val : Lys compared with those receiving 70% Val : Lys and was lowest in piglets receiving the diet with low Val and high Leu content. To further evaluate the interaction between Val and Leu, a dose-response study was carried out in which the response to Val supply was studied in combination with high Leu supply (165% Leu : Lys). Using a curvilinear-plateau model, the average SID Val : Lys requirement was 72%. However, low Val supply (60% SID Val : Lys) reduced performance by 13% to 38%, which was much greater than what we observed in earlier studies. Experiment 4 was carried out to test the hypothesis that the Val requirement is not affected by low Ile supply (50% SID Ile : Lys). Performance was not improved for Val : Lys supplies greater than 65%, which may indicate that Ile (and not Lys) was second-limiting in this study. In conclusion, the first response of piglets to deficient Val supply appears to be a reduction in ADFI, rather than a reduction in ADG or nitrogen retention. A large supply of Leu may not affect the Val requirement per se, but may aggravate the consequences of Val deficiency. PMID:22440413

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

2011-09-01

7

Amino acids  

MedlinePLUS

Amino acids are organic compounds that combine to form proteins . Amino acids and proteins are the building blocks of life. When proteins are digested or broken down, amino acids are left. The human body uses amino acids ...

8

Spectroscopic studies on sidewall carboxylic acid functionalization of multi-walled carbon nanotubes with valine.  

PubMed

The valine functionalized multi-walled carbon nanotubes (MWCNTS) were prepared and characterized by using XRD, UV-Vis, FT-IR, EPR, SEM, and EDX, spectroscopic techniques. The enhanced XRD peak (002) intensity was observed for valine functionalized MWCNTs compared with oxidized MWCNTs, which is likely due to sample purification by acid washing. UV-Vis study shows the formation of valine functionalized MWCNTs. FT-IR study confirms the presence of functional groups of oxidized MWCNTs and valine functionalized MWCNTs. The ESR line shape analysis indicates that the observed EPR line shape is a Gaussian line shape. The g-values indicate that the systems are isotropic in nature. The morphology study was carried out for oxidized MWCNTs and valine functionalized MWCNTs by using SEM. The EDX spectra revealed that the high purity of oxidized MWCNTs and valine functionalized MWCNTs. The functionalization has been chosen because, functionalization of CNTs with amino acids makes them soluble and biocompatible. Thus, they have potential applications in the field of biosensors and targeted drug delivery. PMID:25554963

Deborah, M; Jawahar, A; Mathavan, T; Dhas, M Kumara; Benial, A Milton Franklin

2015-03-15

9

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

10

Amino Acids  

NSDL National Science Digital Library

The Featured Molecules this month are the 20 standard ?-amino acids found in proteins and serve as background to the paper by Barone and Schmidt on the Nonfood Applications of Proteinaceous Renewable Materials. The molecules are presented in two formats, the neutral form and the ionized form found in solution at physiologic pH.

11

Molybdenum(VI) Peroxo alpha-Amino Acid Complexes: Synthesis, Spectra, and Properties of MoO(O(2))(2)(alpha-aa)(H(2)O) for alpha-aa = Glycine, Alanine, Proline, Valine, Leucine, Serine, Asparagine, Glutamine, and Glutamic Acid. X-ray Crystal Structures of the Glycine, Alanine, and Proline Compounds.  

PubMed

The compounds MoO(O(2))(2)(alpha-aa)(H(2)O), alpha-aa = glycine (1), alanine (2), proline (3), valine (4), leucine (5), serine (6), asparagine (7), glutamine (8), and glutamic acid (9), were prepared from the acidic aqueous solutions and characterized by examination of their IR, (1)H and (13)C NMR, and UV-visible spectra. They represent the first complexes containing a peroxo-alpha-amino acid combination in a metal ion ligand sphere. The synthesis and crystallization of these complexes was pH and concentration dependent, and their stability varied for different alpha-amino acids. X-ray structural studies of 1-3 have shown that the alpha-amino acids are coordinated as a zwitterion via one oxygen. This oxygen of the monodentate carboxylato group occupies an equatorial position in a distorted pentagonal bipyramid and encloses the pentagonal ring with the two bidentate peroxo groups. The apical positions are occupied by an oxo group and a water molecule, respectively. The Mo-O(O(2)) bonds are nonsymmetrical, differing in length by 0.009-0.045 Å. The longer bonds are located next to the coordinated carboxylato oxygen. A correlation between O-O and Mo-O bond lengths with the IR and UV-visible spectra of complexes 1-3 is discussed. Crystal structure of MoO(O(2))(2)(alanine)(H(2)O): monoclinic, space group P2(1)/c; Z = 4; a = 10.727(3) Å; b = 8.026(2) Å; c = 10.794(4) Å; beta = 110.81(2) degrees; V = 869 (Å)(3); R = 0.041. (1)H and (13)C NMR spectra in D(2)O solutions showed the presence of one complex species, which decomposed by standing in solution. Analogies and differences between Mo(VI) and V(V) peroxo complexes are outlined. PMID:11669783

Djordjevic, Cirila; Vuletic, Nikola; Jacobs, Bradley A.; Lee-Renslo, Myunghi; Sinn, Ekk

1997-04-23

12

Plasma amino acids  

MedlinePLUS

Amino acids blood test ... types of methods used to determine the individual amino acids levels in the blood. ... test is done to measure the level of amino acids in the blood. An increased level of a ...

13

Inhibitors of Branched Chain Amino Acid Biosynthesis  

NSDL National Science Digital Library

Herbicides that inhibit the production of the branched chain amino acids valine, leucine and isoleucine are used for total vegetation management and selective weed control in a wide variety of crops.  There are currently four different chemical families that share this MOA.  Before the development of glyphosate-tolerance crop technology, branched chain amino acid inhibitors were the mainstay for several major row crops.  While this is still a very important herbicide MOA, the major increase in herbicide resistance weeds since 1980 has been the direct result selection pressure from these herbicides.  There are currently more weed species resistant to branched chain amino acid inhibitors than any other herbicide MOA.

14

Reaction of dehydropyrrolizidine alkaloids with valine and hemoglobin.  

PubMed

Pyrrolizidine alkaloid-containing plants are probably the most common poisonous plants affecting livestock, wildlife, and humans. Pyrrolizidine alkaloids exert toxicity through metabolism to dehydropyrrolizidine alkaloids that bind to cellular protein and DNA, leading to hepatotoxicity, genotoxicity, and tumorigenicity. To date, it is not clear how dehydropyrrolizidine alkaloids bind to cellular constituents, including amino acids and proteins, resulting in toxicity. Metabolism of carcinogenic monocrotaline, riddelliine, and heliotrine produces dehydromonocrotaline, dehyroriddelliine, and dehydroheliotrine, respectively, as primary reactive metabolites. In this study, we report that reaction of dehydromonocrotaline with valine generated four highly unstable 6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP)-derived valine (DHP-valine) adducts. For structural elucidation, DHP-valine adducts were derivatized with phenyl isothiocyanate (PITC) to DHP-valine-PITC products. After HPLC separation, their structures were characterized by mass spectrometry, UV-visible spectrophotometry, (1)H NMR, and (1)H-(1)H COSY NMR spectral analysis. Two DHP-valine-PITC adducts, designated as DHP-valine-PITC-1 and DHP-valine-PITC-3, had the amino group of valine linked to the C7 position of the necine base, and the other two DHP-valine-PITC products, DHP-valine-PITC-2 and DHP-valine-PITC-4, linked to the C9 position of the necine base. DHP-valine-PITC-1 was interconvertible with DHP-valine-PITC-3, and DHP-valine-PITC-2 was interconvertible with DHP-valine-PITC-4. Reaction of dehydroriddelliine and dehydroheliotrine with valine provided similar results. However, reaction of valine and dehydroretronecine (DHR) under similar experimental conditions did not produce DHP-valine adducts. Reaction of dehydromonocrotaline with rat hemoglobin followed by derivatization with PITC also generated the same four DHP-valine-PITC adducts. This represents the first full structural elucidation of protein conjugated pyrrolic adducts formed from reaction of dehydropyrrolizidine alkaloids with an amino acid (valine). In addition, it was found that DHP-valine-2 and DHP-valine-4, with the valine amino group linked at the C7 position of the necine base, can lose the valine moiety to form DHP. PMID:25211425

Zhao, Yuewei; Wang, Shuguang; Xia, Qingsu; Gamboa da Costa, Gonçalo; Doerge, Daniel R; Cai, Lining; Fu, Peter P

2014-10-20

15

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

16

Effects of running the Bostom Marathon on plasma concentrations of large neutral amino acids  

NASA Technical Reports Server (NTRS)

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 valine, leucine, and isoleucine all decreased. These changes in plasma amino acid patterns may influence neurotransmitter synthesis.

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

17

Ferroelectric studies on amino acids mixed TGSP single crystals  

Microsoft Academic Search

Amino acids mixed TGS crystals are of interest due to their high pyroelectric coefficient and low dielectric constant. Partial substitution of phosphate has resulted in triglycine sulpho-phosphate (TGSP), a mixed crystal with improved pyroelectric figure of merit. In order to study the effect of amino acids on the ferroelectric properties of TGSP, we have substituted l-alanine (ATGSP), l-valine (VTGSP), l-asparagine

G. Arunmozhi; R. Jayavel; C. Subramanian

1998-01-01

18

Manipulation of Amino Acid Supply to the Growing Ruminant1  

Microsoft Academic Search

Quality of protein (indicated by amino acid LAAI composition) that enters the small intestine (SI) of growing ruminants is dictated largely by the AA composition of microbial pro- tein. The AA supply is well-balanced and, although individual AA can be experimentally determined to be first- or second-limiting, it seems that several AA (sulfur AA, lysine, histidine, and possibly threonine, valine,

Neal R. Merchen; Evan C. Titgemeyer

19

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

20

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

21

Chemotaxis Toward Amino Acids in Escherichia coli  

PubMed Central

Escherichia coli cells are shown to be attracted to the l-amino acids alanine, asparagine, aspartate, cysteine, glutamate, glycine, methionine, serine, and threonine, but not to arginine, cystine, glutamine, histidine, isoleucine, leucine, lysine, phenylalanine, tryptophan, tyrosine, or valine. Bacteria grown in a proline-containing medium were, in addition, attracted to proline. Chemotaxis toward amino acids is shown to be mediated by at least two detection systems, the aspartate and serine chemoreceptors. The aspartate chemoreceptor was nonfunctional in the aspartate taxis mutant, which showed virtually no chemotaxis toward aspartate, glutamate, or methionine, and reduced taxis toward alanine, asparagine, cysteine, glycine, and serine. The serine chemoreceptor was nonfunctional in the serine taxis mutant, which was defective in taxis toward alanine, asparagine, cysteine, glycine, and serine, and which showed no chemotaxis toward threonine. Additional data concerning the specificities of the amino acid chemoreceptors with regard to amino acid analogues are also presented. Finally, two essentially nonoxidizable amino acid analogues, ?-aminoisobutyrate and ?-methylaspartate, are shown to be attractants for E. coli, demonstrating that extensive metabolism of attractants is not required for amino acid taxis. PMID:4562400

Mesibov, Robert; Adler, Julius

1972-01-01

22

Biosynthesis of 'essential' amino acids by scleractinian corals.  

PubMed Central

Animals rely on their diet for amino acids that they are incapable either of synthesizing or of synthesizing in sufficient quantities to meet metabolic needs. These are the so-called 'essential amino acids'. This set of amino acids is similar among the vertebrates and many of the invertebrates. Previously, no information was available for amino acid synthesis by the most primitive invertebrates, the Cnidaria. The purpose of this study was to examine amino acid synthesis by representative cnidarians within the Order Scleractinia. Three species of zooxanthellate reef coral, Montastraea faveolata, Acropora cervicornis and Porites divaricata, and two species of non-zooxanthellate coral, Tubastrea coccinea and Astrangia poculata, were incubated with 14C-labelled glucose or with the 14C-labelled amino acids glutamic acid, lysine or valine. Radiolabel tracer was followed into protein amino acids. A total of 17 amino acids, including hydroxyproline, were distinguishable by the techniques used. Of these, only threonine was not found radiolabelled in any of the samples. We could not detect tryptophan or cysteine, nor distinguish between the amino acid pairs glutamic acid and glutamine, or aspartic acid and asparagine. Eight amino acids normally considered essential for animals were made by the five corals tested, although some of them were made only in small quantities. These eight amino acids are valine, isoleucine, leucine, tyrosine, phenylalanine histidine, methionine and lysine. The ability of cnidarians to synthesize these amino acids could be yet another indicator of a separate evolutionary history of the cnidarians from the rest of the Metazoa. PMID:9078264

Fitzgerald, L M; Szmant, A M

1997-01-01

23

Amino acids in modern and fossil woods  

NASA Technical Reports Server (NTRS)

The amino acid composition and the extent of racemization in several modern and fossil woods are reported. The method of analysis is described, and data are presented on the total amino acid concentration, the amino acid ratios, and the enantiomeric ratios in each sample. It is found that the amino acid concentration per gram of dry wood decreases with age of the sample, that the extent of racemization increases with increasing age, and that the amounts of aspartic acid, threonine, and serine decrease relative to valine with increasing age. The relative racemization rates of amino acids in wood, bone, and aqueous solution are compared, and it is shown that racemization in wood is much slower than in bone or aqueous solution. Racemization results for woods from the Kalambo Falls area of Zambia are used to calculate a minimum age of 110,000 years for the transition between the Sangoan and Acheulian industries at that site. This result is shown to be consistent with numerous radiometric dates for older Acheulian sites in Africa and to compare well with geologically inferred dates for the beginning of the Eemian and the end of the Acheulian industry in southern Africa.

Lee, C.; Bada, J. L.; Peterson, E.

1976-01-01

24

Amino Acids and Chirality  

NASA Technical Reports Server (NTRS)

Amino acids are among the most heavily studied organic compound class in carbonaceous chondrites. The abundance, distributions, enantiomeric compositions, and stable isotopic ratios of amino acids have been determined in carbonaceous chondrites fi'om a range of classes and petrographic types, with interesting correlations observed between these properties and the class and typc of the chondritcs. In particular, isomeric distributions appear to correlate with parent bodies (chondrite class). In addition, certain chiral amino acids are found in enantiomeric excess in some chondrites. The delivery of these enantiomeric excesses to the early Earth may have contributed to the origin of the homochirality that is central to life on Earth today. This talk will explore the amino acids in carbonaceous chondritcs and their relevance to the origin of life.

Cook, Jamie E.

2012-01-01

25

Bioconversion of 2-amino acids to 2-hydroxy acids by Clostridium butyricum  

Microsoft Academic Search

Analysis by gas chromatography-mass spectrometry (GC-MS) of 24-h cultures of Clostridium butyricum type strain in synthetic BMG medium supplemented with various 2-amino acids (10 mM) revealed the presence of the corresponding 2-hydroxy acids. C. butyricum was able to bioconvert l-valine, dl-norvaline, l-leucine, dl-norleucine, l-methionine and l-phenylalanine as well as unusual 2-amino acids, i.e., l-2-aminobutyric acid, l-2-amino-4-pentenoic acid, dl-2-aminooctanoic acid, and

Nasser Khelifa; Annabelle Dugay; Annie-Claude Tessedre; François Guyon; Alain Rimbault

1998-01-01

26

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. PMID:17656140

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

2010-01-01

27

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

28

Profile of Plasma Amino Acid Levels in Rats Exposed to Acute Hypoxic Hypoxia  

Microsoft Academic Search

The effect of acute hypoxic hypoxia on the profile of plasma amino acids in rats was studied and compared to that resulting\\u000a from acute liver injury induced by giving carbon tetrachloride. In hypoxic rats exposed to 45% air in N2 for 5 h, the concentrations of branched chain amino acids, including valine, leucine and isoleucine, and aromatic amino acids\\u000a such as

Haruhiro Muratsubaki; Akiko Yamaki

29

Brain amino acid sensing.  

PubMed

The 20 different amino acids, in blood as well as in the brain, are strictly maintained at the same levels throughout the day, regardless of food intake. Gastric vagal afferents only respond to free glutamate and sugars, providing recognition of food intake and initiating digestion. Metabolic control of amino acid homeostasis and diet-induced thermogenesis is triggered by this glutamate signalling in the stomach through the gut-brain axis. Rats chronically fed high-sugar and high-fat diets do not develop obesity when a 1% (w/v) monosodium glutamate (MSG) solution is available in a choice paradigm. Deficiency of the essential amino acid lysine (Lys) induced a plasticity in rats in response to Lys. This result shows how the body is able to identify deficient nutrients to maintain homeostasis. This plastic effect is induced by activin A activity in the brain, particularly in certain neurons in the lateral hypothalamic area (LHA) which is the centre for amino acid homeostasis and appetite. These neurons respond to glutamate signalling in the oral cavity by which umami taste is perceived. They play a quantitative role in regulating ingestion of deficient nutrients, thereby leading to a healthier life. After recovery from malnutrition, rats prefer MSG solutions, which serve as biomarkers for protein nutrition. PMID:25200295

Tsurugizawa, T; Uneyama, H; Torii, K

2014-09-01

30

Heat-initiated prebiotic formation of peptides from glycine/aspartic acid and glycine/valine in aqueous environment and clay suspension  

NASA Astrophysics Data System (ADS)

The effect of heat on the reaction system of glycine/aspartic acid and glycine/valine in the aqueous environment as well as in montmorillonite clay suspension with or without divalent cations (Ca2+, Mg2+ and Ni2+) has been investigated at 85°C±5°C for varying periods under prebiotic drying and wetting conditions. The resulting products were analysed and characterized by chromatographic and spectroscopic methods. Peptide formation appears to depend on the duration of heat effect, nature of reactant amino acids and, to some extent, on montmorillonite clay incorporated with divalent cations. In the glycine/aspartic acid system, oligomerization of glycine was limited up to trimer level (Gly)3 along with the formation of glycyl-aspartic acid, while linear and cyclic peptides of aspartic acid were not formed, whereas the glycine/valine system preferentially elongated homo-oligopeptide of glycine up to pentamer level (Gly)5 along with formation of hetero-peptides (Gly-Val and Val-Gly). These studies are relevant in the context of the prebiotic origin of proteins and the role of clay and metal ions in condensation and oligomerization of amino acids. The length of the bio-oligomer chain depends upon the reaction conditions. However, condensation into even a small length seems significant, as the same process would have taken millions of years in the primitive era of the Earth, leading to the first proteins.

Pant, Chandra Kala; Lata, Hem; Pathak, Hari Datt; Mehata, Mohan Singh

2009-04-01

31

Quantification of racemization of amino acids in alkaline-treated duck eggs by micellar capillary electrophoresis.  

PubMed

Duck eggs were pickled in 4.2% NaOH/5% NaCl solution for 20 days to prepare the traditional Chinese Pidan. The extent of racemization of compositional amino acid in egg albumen and yolk over the alkaline pickling period was investigated with micellar capillary electrophoresis (MCE) using beta-cyclodextrin as chiral selector. The racemization value of amino acids in egg albumen was in the order serine > aspartic acid > glutamic acid > phenylalanine > leucine > valine > threonine = isoleucine, whereas the order in egg yolk was aspartic acid > glutamic acid > phenylalanine > leucine > valine. Therefore, the tendency of amino acid racemization appeared to be closely related to the properties of its residual side chain, as well as the pH and alkaline treating period. Moreover, racemization of most of the amino acids was remarkably induced by the alkaline treatment during the initial pickling period. PMID:10563920

Chang, H M; Tsai, C F; Li, C F

1999-02-01

32

Novel renal amino acid transporters.  

PubMed

Reabsorption of amino acids, similar to that of glucose, is a major task of the proximal kidney tubule. Various amino acids are actively transported across the luminal brush border membrane into proximal tubule epithelial cells, most of which by cotransport. An important player is the newly identified cotransporter (symporter) B0AT1 (SLC6A19), which imports a broad range of neutral amino acids together with Na+ across the luminal membrane and which is defective in Hartnup disorder. In contrast, cationic amino acids and cystine are taken up in exchange for recycled neutral amino acids by the heterodimeric cystinuria transporter. The basolateral release of some neutral amino acids into the extracellular space is mediated by unidirectional efflux transporters, analogous to GLUT2, that have not yet been definitively identified. Additionally, cationic amino acids and some other neutral amino acids leave the cell basolaterally via heterodimeric obligatory exchangers. PMID:15709970

Verrey, François; Ristic, Zorica; Romeo, Elisa; Ramadan, Tamara; Makrides, Victoria; Dave, Mital H; Wagner, Carsten A; Camargo, Simone M R

2005-01-01

33

2-Amino-3-(Oxirane-2,3-Dicarboxamido)-Propanoyl-Valine, an Effective Peptide Antibiotic from the Epiphyte Pantoea agglomerans 48b/90 ?  

PubMed Central

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

2009-01-01

34

Enantiomeric separation of amino acids and nonprotein amino acids using a particle-loaded  

E-print Network

Enantiomeric separation of amino acids and nonprotein amino acids using a particle acids and three nonprotein amino acids are derivatized with the fluorogenic reagent 4-fluoro-7-nitro-2 liquid chromatography (HPLC). Keywords: Amino acid / Nonprotein amino acid / Capillary

Zare, Richard N.

35

Solubility of xenon in amino-acid solutions. II. Nine less-soluble amino acids  

NASA Astrophysics Data System (ADS)

Ostwald solubility (L) of xenon gas, as the radioisotope 133Xe, has been measured as a function of solute concentration, at 25.0 °C, in aqueous solutions of nine amino acids. The amino-acid concentrations investigated covered much of their solubility ranges in water, viz., asparagine monohydrate (0-0.19 M), cysteine (0-1.16 M), glutamine (0-0.22 M), histidine (0-0.26 M), isoleucine (0-0.19 M), methionine (0-0.22 M), serine (0-0.38 M), threonine (0-1.4 M), and valine (0-0.34 M). We have previously reported solubility results for aqueous solutions of six other, generally more soluble, amino acids (alanine, arginine, glycine, hydroxyproline, lysine, and proline), of sucrose and sodium chloride. In general, L decreases approximately linearly with increasing solute concentration in these solutions. If we postulate that the observed decreases in gas solubility are due to hydration, the results under some assumptions can be used to calculate hydration numbers (H), i.e., the number of H2O molecules associated with each amino-acid solute molecule. The average values of hydration number (H¯) obtained at 25.0 °C are 15.3±1.5 for asparagine, 6.8±0.3 for cysteine, 11.5±1.1 for glutamine, 7.3±0.7 for histidine, 5.9±0.4 for isoleucine, 10.6±0.8 for methionine, 11.2±1.3 for serine, 7.7± 1.0 for threonine, and 6.6±0.6 for valine. We have also measured the temperature dependence of solubility L(T) from 5-40 °C for arginine, glycine, and proline, and obtained hydration numbers H¯(T) in this range. Between 25-40 °C, arginine has an H¯ near zero. This may be evidence for an attractive interaction between xenon and arginine molecules in aqueous solution.

Kennan, Richard P.; Himm, Jeffrey F.; Pollack, Gerald L.

1988-05-01

36

Branched-chain Amino Acid Metabolon  

PubMed Central

The catabolic pathway for branched-chain amino acids includes deamination followed by oxidative decarboxylation of the deaminated product branched-chain ?-keto acids, catalyzed by the mitochondrial branched-chain aminotransferase (BCATm) and branched-chain ?-keto acid dehydrogenase enzyme complex (BCKDC). We found that BCATm binds to the E1 decarboxylase of BCKDC, forming a metabolon that allows channeling of branched-chain ?-keto acids from BCATm to E1. The protein complex also contains glutamate dehydrogenase (GDH1), 4-nitrophenylphosphatase domain and non-neuronal SNAP25-like protein homolog 1, pyruvate carboxylase, and BCKDC kinase. GDH1 binds to the pyridoxamine 5?-phosphate (PMP) form of BCATm (PMP-BCATm) but not to the pyridoxal 5?-phosphate-BCATm and other metabolon proteins. Leucine activates GDH1, and oxidative deamination of glutamate is increased further by addition of PMP-BCATm. Isoleucine and valine are not allosteric activators of GDH1, but in the presence of 5?-phosphate-BCATm, they convert BCATm to PMP-BCATm, stimulating GDH1 activity. Sensitivity to ADP activation of GDH1 was unaffected by PMP-BCATm; however, addition of a 3 or higher molar ratio of PMP-BCATm to GDH1 protected GDH1 from GTP inhibition by 50%. Kinetic results suggest that GDH1 facilitates regeneration of the form of BCATm that binds to E1 decarboxylase of the BCKDC, promotes metabolon formation, branched-chain amino acid oxidation, and cycling of nitrogen through glutamate. PMID:19858196

Islam, Mohammad Mainul; Nautiyal, Manisha; Wynn, R. Max; Mobley, James A.; Chuang, David T.; Hutson, Susan M.

2010-01-01

37

Accumulation, selection and covariation of amino acids in sieve tube sap of tansy (Tanacetum vulgare) and castor bean (Ricinus communis): evidence for the function of a basic amino acid transporter and the absence of a ?-amino butyric acid transporter.  

PubMed

Sieve tube sap was obtained from Tanacetum by aphid stylectomy and from Ricinus after apical bud decapitation. The amino acids in sieve tube sap were analyzed and compared with those from leaves. Arginine and lysine accumulated in the sieve tube sap of Tanacetum more than 10-fold compared to the leaf extracts and they were, together with asparagine and serine, preferably selected into the sieve tube sap, whereas glycine, methionine/tryptophan and ?-amino butyric acid were partially or completely excluded. The two basic amino acids also showed a close covariation in sieve tube sap. The acidic amino acids also grouped together, but antagonistic to the other amino acids. The accumulation ratios between sieve tube sap and leaf extracts were smaller in Ricinus than in Tanacetum. Arginine, histidine, lysine and glutamine were enriched and preferentially loaded into the phloem, together with isoleucine and valine. In contrast, glycine and methionine/tryptophan were partially and ?-amino butyric acid almost completely excluded from sieve tube sap. The covariation analysis grouped arginine together with several neutral amino acids. The acidic amino acids were loaded under competition with neutral amino acids. It is concluded from comparison with the substrate specificities of already characterized plant amino acid transporters, that an AtCAT1-like transporter functions in phloem loading of basic amino acids, whereas a transporter like AtGAT1 is absent in phloem. Although Tanacetum and Ricinus have different minor vein architecture, their phloem loading specificities for amino acids are relatively similar. PMID:24446756

Bauer, Susanne N; Nowak, Heike; Keller, Frank; Kallarackal, Jose; Hajirezaei, Mohamad-Reza; Komor, Ewald

2014-09-01

38

A valine-resistant mutant of Arabidopsis thaliana displays an acetolactate synthase with altered feedback control  

Microsoft Academic Search

A valine-resistant mutant line, VAL-2, of Arabidopsis thaliana (L.) Heynh. was identified by screening M 2 populations of ethylmethane-sulfonate-mutagenized seeds. The resistance was found to be due to a single, dominant, nuclear gene mutation. Assay of acetolactate synthase (ALS) indicated that the valine resistance in this mutant is caused by decreased sensitivity of ALS to the branched-chain amino acids, valine,

K. Wu; G. Mourad; J. King

1994-01-01

39

A valine-resistant mutant of Arabidopsis thaliana displays an acetolactate synthase with altered feedback control  

Microsoft Academic Search

A valine-resistant mutant line, VAL-2, ofArabidopsis thaliana (L.) Heynh. was identified by screening M 2 populations of ethylmethane-sulfonate-mutagenized seeds. The resistance was found to be due to a single, dominant, nuclear gene mutation. Assay of acetolactate synthase (ALS) indicated that the valine resistance in this mutant is caused by decreased sensitivity of ALS to the branched-chain amino acids, valine, leucine

K. Wu; G. Mourad; J. King

1994-01-01

40

A Stereodivergent Approach to Amino Acids, Amino Alcohols, or  

E-print Network

A Stereodivergent Approach to Amino Acids, Amino Alcohols, or Oxazolidinones of High Enantiomeric of r-amino acids, amino alcohols, or oxazolidinones. The sequence includes the SN2 displacement by a cuprate reagent and a Curtius rearrangement as key steps. Amino acids1 and amino alcohols2,3 are compounds

Spino, Claude

41

Effect of a valine-rich diet on a rat model of short bowel syndrome  

Microsoft Academic Search

It has been recently reported that valine, which was one of the branched chain amino acids, enhanced liver regeneration after a hepatectomy in rats. The aim of this study is to investigate the effect of enteral valine supplementation on the intestinal adaptation of short bowel syndrome using a rat model. Seven-week-old male Lewis rats underwent a 90% small bowel resection.

Narito Takada; Keiko Ogita; Tomoaki Taguchi; Kouji Masumoto; Sachiyo Suita

2005-01-01

42

Preferential Treatment: Interaction Between Amino Acids and Minerals  

NASA Astrophysics Data System (ADS)

Amino acids are the building blocks of proteins and are important for some models of the origin of life. Polymerization of amino acids from dilute solution is unlikely without a scaffold or catalyst. The surfaces of early Earth minerals are the most likely candidates for this role. The surface adsorption behavior of 12 amino acids (L-alanine, L-serine, L-aspartic acid, L-proline, L- phenylalanine, L-valine, L-arginine, d-amino valeric acid, glycine, L-lysine, L-isoleucine, and B-alanine) on 21 minerals (quartz, calcite, enstatite, illite, olivine, pyrrhotite, pyrite, alkali basalt, albite, analcime, chlorite, barite, hydroxyl apatite, hematite, magnetite, aluminum hydroxide, kaolin, silica gel, corundum, rutile, and montmorillonite) was determined via batch adsorption experiments. Absorption was determined for concentrations between 10-4M and 10-6M in the presence of 0.1M NaCl, and between pH values of 3 and 9 at 25 degrees C. The equilibrated solutions were centrifuged, filtered, derivatized using a fluorescent amino group tag (dansyl-chloride) and analyzed by HPLC. Adsorption was standardized using BET surface area measurements for each mineral to give the number of mols of each amino acid adsorbed per square meter for each mineral. The results indicate an enormous difference in the adsorption of amino acids between minerals, along with major differences in the adsorption of individual amino acids on the same mineral surface. There is also a change in the absorbance of amino acids as the pH changes. Many previous studies of amino acid concentration and catalysis by minerals have used clay minerals because of their high surface areas, however, this data suggests that the surfaces of minerals such as calcite, quartz and pyrite have even higher affinities for amino acids. The results suggest mineral surfaces that could be optimal locations for the polymerization of molecules linked to the origin of life.

Crapster-Pregont, E. J.; Cleaves, H. J.; Hazen, R. M.

2008-12-01

43

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

44

Cerebrospinal fluid amino acids in pathological gamblers and healthy controls.  

PubMed

Amino acids, such as valine, isoleucine and leucine compete with tyrosine and tryptophan for transport into the brain and might thus affect the central serotonin and catecholamine patterns. Furthermore, the excitatory amino acids glutamic acid, aspartic acid and glycine are known to act on the N-methyl-D-aspartate receptor, which is part of the reward system. Based on these facts, we have explored the role of cerebrospinal fluid (CSF) amino acids in pathological gambling. Concentrations of amino acids were determined in CSF obtained from one female and 11 pathological male gamblers and 11 healthy male controls. In an ANCOVA with best subset regression, pathological male gamblers had higher CSF levels of the excitatory glutamic and aspartic acids, as well as of phenylalanine, isoleucine, citrulline and glycine. A negative contribution of glycine in interaction with the neuraxis distance might mirror a reduced spinal supply or an altered elimination of glycine in pathological gamblers. A decreasing CSF gradient from the first (0-6 ml) to the third (13-18 ml) CSF fraction was found for glutamic acid, glycine, leucine, isoleucine, lysine, ornithine and glutamine in both pathological gamblers and healthy controls. A decreasing gradient was found, however, for aspartic acid and phenylalanine in pathological male gamblers. The altered pattern of CSF amino acids in pathological gamblers might exert an influence on central monoamines as well as on N-methyl-D-aspartate receptor function. PMID:18259089

Nordin, Conny; Gupta, Ramesh C; Sjödin, Ingemar

2007-01-01

45

An Abstracting Transformation for Amino Acid Polymorphism  

E-print Network

An Abstracting Transformation for Amino Acid Polymorphism Anthony M. Castaldo, PhD Research three nucleotide se- quences (a codon) into amino acids: Amino Acid (or signal) Codons A (Alanine) GCT believe what is important is the sequence of amino acids produced, and because amino acids average about

Texas at San Antonio, University of

46

Amino Acids from a Comet  

NASA Technical Reports Server (NTRS)

NASA's Stardust spacecraft returned samples from comet 81P/Wild 2 to Earth in January 2006. Examinations of the organic compounds in cometary samples can reveal information about the prebiotic organic inventory present on the early Earth and within the early Solar System, which may have contributed to the origin of life. Preliminary studies of Stardust material revealed the presence of a suite of organic compounds including several amines and amino acids, but the origin of these compounds (cometary- vs. terrestrial contamination) could not be identified. We have recently measured the carbon isotopic ratios of these amino acids to determine their origin, leading to the first detection of a coetary amino acid.

Cook, Jamie Elisla

2009-01-01

47

Transport of branched-chain amino acids in brain slices of developing and adult rats.  

PubMed

The accumulation of labelled leucine, isoleucine and valine by cerebral slices of developing and adult rats was studied. The accumulation increased with age by 15-25%. It was strongly (from 52 to 86%) inhibited by a 100-fold excess of phenylalanine, tryptophan and another branched-chain amino acid, but moderately activated by GABA and glutamate. The inhibitions evoked by leucine and isoleucine were slightly stronger in young than in adult rats. The corresponding 2-oxoacid analogs of leucine, isoleucine and valine were also inhibitory but less effective. The 30-min accumulation of 3H-labelled branched-chain amino acids was ostensibly higher than the increase in their total concentrations in incubated slices, which apparently bespeaks lively homoexchange of endogenous intracellular and labelled extracellular amino acids. PMID:6516888

Pajari, M

1984-11-01

48

Analysis of amino acids in nectar from pitchers of Sarracenia purpurea (Sarraceniaceae).  

PubMed

Sarracenia purpurea L. (northern pitcher plant) is an insectivorous plant with extrafloral nectar that attracts insects to a water-filled pitfall trap. We identified and quantified the amino acids in extrafloral nectar produced by pitchers of S. purpurea. Nectar samples were collected from 32 pitchers using a wick-sampling technique. Samples were analyzed for amino acids with reverse-phase high-performance liquid chromatography with phenylisothiocyanate derivatization. Detectable amounts of amino acids were found in each of the 32 nectar samples tested. Mean number of amino acids in a nectar sample was 9 (SD = 2.2). No amino acid was detected in all 32 samples. Mean amount of amino acids in a nectar sample (i.e., amount per wick) was 351.4 ng (SD = 113.2). Nine amino acids occurred in 20 of the 32 samples (aspartic acid, cysteine, glutamic acid, glycine, histidine, hydroxyproline, methionine, serine, valine) averaging 263.4 ng (SD = 94.9), and accounting for ~75% of the total amino acid content. Nectar production may constitute a significant cost of carnivory since the nectar contains amino acids. However, some insects prefer nectar with amino acids and presence of amino acids may increase visitation and capture of insect prey. PMID:21708574

Dress, W; Newell, S; Nastase, A; Ford, J

1997-12-01

49

Industrial production of amino acids by coryneform bacteria.  

PubMed

In the 1950s Corynebacterium glutamicum was found to be a very efficient producer of L-glutamic acid. Since this time biotechnological processes with bacteria of the species Corynebacterium developed to be among the most important in terms of tonnage and economical value. L-Glutamic acid and L-lysine are bulk products nowadays. L-Valine, L-isoleucine, L-threonine, L-aspartic acid and L-alanine are among other amino acids produced by Corynebacteria. Applications range from feed to food and pharmaceutical products. The growing market for amino acids produced with Corynebacteria led to significant improvements in bioprocess and downstream technology as well as in molecular biology. During the last decade big efforts were made to increase the productivity and to decrease the production costs. This review gives an overview of the world market for amino acids produced by Corynebacteria. Significant improvements in bioprocess technology, i.e. repeated fed batch or continuous production are summarised. Bioprocess technology itself was improved furthermore by application of more sophisticated feeding and automatisation strategies. Even though several amino acids developed towards commodities in the last decade, side aspects of the production process like sterility or detection of contaminants still have increasing relevance. Finally one focus of this review is on recent developments in downstream technology. PMID:12948636

Hermann, Thomas

2003-09-01

50

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. PMID:395764

Forster, R. P.; Goldstein, L.

1979-01-01

51

Excretion of amino acids by humans during space flight  

NASA Technical Reports Server (NTRS)

We measured the urine amino acid distribution patterns before, during and after space flight on the Space Shuttle. The urine samples were collected on two separate flights of the space shuttle. The first flight lasted 9.5 days and the second flight 15 days. Urine was collected continuously on 8 subjects for the period beginning 10 d before launch to 6 d after landing. Results: In contrast to the earlier Skylab missions where a pronounced amino aciduria was found, on shuttle the urinary amino acids showed little change with spaceflight except for a marked decrease in all of the amino acids on FD (flight day) 1 (p<0.05) and a reduction in isoleucine and valine on FD3 and FD4 (p<0.05). Conclusions: (i) Amino aciduria is not an inevitable consequence of space flight. (ii) The occurrence of amino aciduria, like muscle protein breakdown is a mission specific effect rather than part of the general human response to microgravity.

Stein, T. P.; Schluter, M. D.

1998-01-01

52

Non-racemic amino acids in the Murray and Murchison meteorites  

NASA Astrophysics Data System (ADS)

Small (1.0-9.2%) L-enantiomer excesses were found in six ?-methyl-?-amino alkanoic acids from the Murchison (2.8-9.2%) and Murray (1.0-6.0%) carbonaceous chondrites by gas chromatography-mass spectroscopy of their N-trifluoroacetyl or N-pentafluoropropyl isopropyl esters. These amino acids [2-amino-2,3-dimethylpentanoic acid (both diastereomers), isovaline, ?-methyl norvaline, ?-methyl valine, and ?-methyl norleucine] are either unknown or rare in the terrestrial biosphere. Enantiomeric excesses were either not observed in the four ?-H-?-amino alkanoic acids analyzed (?-amino- n-butyric acid, norvaline, alanine, and valine) or were attributed to terrestrial contamination. The substantial excess of L-alanine reported by others was not found in the alanine in fractionated extracts of either meteorite. The enantiomeric excesses reported for the ?-methyl amino acids may be the result of partial photoresolution of racemic mixtures caused by ultraviolet circularly polarized light in the presolar cloud. The ?-methyl-?-amino alkanoic acids could have been significant in the origin of terrestrial homochirality given their resistance to racemization and the possibility for amplification of their enantiomeric excesses suggested by the strong tendency of their polymers to form chiral secondary structure.

Pizzarello, S.; Cronin, J. R.

2000-01-01

53

Branched-chain amino acid catabolism and cancer cachexia (review).  

PubMed

The present study focuses on the role of branched-chain amino acids (BCAA) (leucine, isoleucine and valine) in cancer cachexia. This is a frequent and devastating complication of cancer occurring in more than two thirds of patients who die with advanced cancer, and in up to 22% of cancer deaths it is the only abnormality found at autopsy. BCAA are essential amino acids often increased in cancer patients and this phenomenon may be related with increased protein degradation in skeletal muscle and consequently, cancer cachexia. The relevance of this association in medical terms is evident, future investigations may focus on therapeutical strategies based on the administration of BCAA to cachectic patients. PMID:21594436

Argiles, J; Costelli, P; Carbo, N; Lopezsoriano, F

1996-07-01

54

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

55

in amino-acid concentration enhanced amino-acid and glucose utilization for lipogenesis, with no  

E-print Network

in amino-acid concentration enhanced amino- acid and glucose utilization for lipogenesis more strongly amino-acid and glucose incorporation into cellular lipids, the glu- cose incorporation showed a synergistic effect between insulin and amino acids for up to 1.59 g/I amino acid in the medium

Boyer, Edmond

56

The standard amino acids alanine ala A  

E-print Network

The standard amino acids alanine ala A cysteine cys C aspartic acid asp D glutamic acid glu E's the mapping from nucleotide triplets in DNA sequences (via messenger RNA) to individual amino acids, and T) but only 20 amino acids, and that the code is redundant or "degenerate" in the sense that several

Guevara-Vasquez, Fernando

57

Effect of whey protein on plasma amino acids in diabetic mice  

PubMed Central

The aim of this study was to investigate the effect of whey protein on plasma amino acid levels in a mouse model of type II diabetes, using high-performance liquid chromatography (HPLC). The composition and content of amino acids in the whey proteins were analyzed using HPLC. Type I and type II diabetic mouse models were prepared using streptozotocin (STZ) and normal mice were used as a control. The ICR mice in each group were then randomly divided into four subgroups, to which 0, 10, 20 and 40% whey protein, respectively, was administered for four weeks. Changes in the plasma amino acid levels were observed in each group. The proportions of leucine, isoleucine and valine in the whey proteins were 14.40, 5.93 and 5.32% of the total amino acids, respectively, that is, the branched-chain amino acid content was 25.65%. The levels of branched-chain amino acids increased in the plasma of the normal and model mice following the administration of whey proteins by gavage and the amino acid levels increased as the concentration of the administered protein increased. In addition, the branched-chain amino acid levels in the blood of the model mice were higher than those in the normal mice. The levels of plasma amino acids in diabetic mice increased following gavage with whey protein, which is rich in branched-chain amino acids. PMID:24255674

HAN, TING; CAI, DONGLIAN; GENG, SHANSHAN; WANG, YING; ZHEN, HUI; WU, PEIYING

2013-01-01

58

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. PMID:22303262

Binder, Stefan

2010-01-01

59

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. PMID:5965349

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

1966-01-01

60

Combinatorics of aliphatic amino acids  

NASA Astrophysics Data System (ADS)

This study combines biology and mathematics, showing that a relatively simple question from molecular biology can lead to complicated mathematics. The question is how to calculate the number of theoretically possible aliphatic amino acids as a function of the number of carbon atoms in the side chain. The presented calculation is based on earlier results from theoretical chemistry concerning alkyl compounds. Mathematical properties of this number series are highlighted. We discuss which of the theoretically possible structures really occur in living organisms, such as leucine and isoleucine with a chain length of four. This is done both for a strict definition of aliphatic amino acids only involving carbon and hydrogen atoms in their side chain and for a less strict definition allowing sulphur, nitrogen and oxygen atoms. While the main focus is on proteinogenic amino acids, we also give several examples of non-proteinogenic aliphatic amino acids, playing a role, for instance, in signalling. The results are in agreement with a general phenomenon found in biology: Usually, only a small number of molecules are chosen as building blocks to assemble an inconceivable number of different macromolecules as proteins. Thus, natural biological complexity arises from the multifarious combination of building blocks.

Grützmann, Konrad; Böcker, Sebastian; Schuster, Stefan

2011-01-01

61

Evaluation of channel function after alteration of amino acid residues at the pore center of KCNQ1 channel  

Microsoft Academic Search

The effect of the electrical charge or the size of the amino acid residue at the pore center of a slowly activation component of the delayed rectifier potassium channel: KCNQ1 was studied. K+ currents were measured after transfection of one of four KCNQ1 mutants: substituting Isoleucine with Lysine, Glutamate, Valine or Glycine and then transfected in COS-7 cells. Both the

Taruna Ikrar; Haruo Hanawa; Hiroshi Watanabe; Yoshiyasu Aizawa; Mahmoud M. Ramadan; Masaomi Chinushi; Minoru Horie; Yoshifusa Aizawa

2009-01-01

62

Addition of amino acid moieties to lapatinib increases the anti-cancer effect via amino acid transporters.  

PubMed

Anti-cancer agents delivered to cancer cells often show multi-drug resistance (MDR) due to expulsion of the agents. One way to address this problem is to increase the accumulation of anti-cancer agents in cells via amino acid transporters. Thus, val-lapatinib and tyr-lapatinib were newly synthesized by adding valine and tyrosine moieties, respectively, to the parent anti-cancer agent lapatinib without stability issues in rat plasma. Val-lapatinib and tyr-lapatinib showed enhanced anti-cancer effects versus the parent lapatinib in various cancer cell lines, including human breast cancer cells (MDA-MB-231, MCF7) and lung cancer cells (A549), but not in non-cancerous MDCK-II cells. A glutamine uptake study revealed that both val-lapatinib and tyr-lapatinib, but not the parent lapatinib, inhibited glutamine transport in MDA-MB-231 and MCF7 cells, suggesting the involvement of amino acid transporters. In conclusion, val-lapatinib and tyr-lapatinib have enhanced anti-cancer effects, likely due to an increased uptake of the agents into cancer cells via amino acid transporters. The present data suggest that amino acid transporters may be an effective drug delivery target to increase the uptake of anti-cancer agents, leading to one method of overcoming MDR in cancer cells. PMID:24151179

Maeng, Han-Joo; Kim, Eun-Seo; Chough, Chieyeon; Joung, Misuk; Lim, Jee Woong; Shim, Chang-Koo; Shim, Won-Sik

2014-01-01

63

Investigation of 60Co ?-irradiated L-(-) malic acid, N-methyl- DL-valine and L-glutamic acid ?-ethyl ester by electron paramagnetic resonance technique  

NASA Astrophysics Data System (ADS)

The electron paramagnetic resonance spectra of ?-irradiated L-(-) malic acid, N-methyl- DL-valine and L-glutamic acid ?-ethyl ester powders have been investigation at room temperature. Radiation damage centres are attributed to HOOCCH 2?HCOOH, (CH 3) 2?CH(NHCH 3)COOH and C 2H 5OCOCH 2CH 2?(NH 2)COOH radicals, respectively. The spectra have been computer simulated. The EPR parameters of the observed radicals have been determined and discussed.

Ba?kan, M. Halim; Ayd?n, Murat; Osmano?lu, ?emsettin

64

Nonprotein Amino Acids in the Murchison Meteorite  

PubMed Central

Twelve nonprotein amino acids appear to be present in the Murchison meteorite. The identity of eight of them has been conclusively established as N-methylglycine, ?-alanine, 2-methylalanine, ?-amino-n-butyric acid, ?-amino-n-butyric acid, ?-amino-n-butyric acid, isovaline, and pipecolic acid. Tentative evidence is presented for the presence of N-methylalanine, N-ethylglycine, ?-aminoisobutyric acid, and norvaline. These amino acids appear to be extraterrestrial in origin and may provide new evidence for the hypothesis of chemical evolution. PMID:16591908

Kvenvolden, Keith A.; Lawless, James G.; Ponnamperuma, Cyril

1971-01-01

65

Protein Synthesis Inhibition in Neocortical Grafts Evaluated by Systemic Amino Acid Uptake Autoradiography  

Microsoft Academic Search

The temporal pattern of protein synthesis inhibition was examined in grafted neocortical neurons using [3H]valine in vivo autoradiography. Neuronal uptake levels of systemically administered 3H-labeled amino acids which cross the blood–brain barrier (BBB) via endothelial cell neutral carriers have long been a hallmark in studies of experimental ischemic pathology; there is likely a strong correlation between persistent protein synthesis inhibition

Jeffrey M. Rosenstein; William F. Silverman

2000-01-01

66

Adsorption behavior of cationic and anionic species on chitosan resins possessing amino acid moieties.  

PubMed

Chitosan resins modified with amino acids, such as glycine, valine, leucine, and serine, were synthesized for investigating the adsorption behavior of cationic and anionic species, and showed good abilities for the adsorption of trace elements in aquatic media as follows: glycine for lanthanoids at pH 7, leucine for molybdenum at pH 1-5, serine for uranium at pH 2-7, and amino acids for bismuth at pH 1-7. Cationic and anionic species could be adsorbed by a chelating mechanism and an anion-exchange mechanism. PMID:18071231

Oshita, Koji; Takayanagi, Toshio; Oshima, Mitsuko; Motomizu, Shoji

2007-12-01

67

[Features of amino acid assimilation by representatives of the Mycoplasma genus].  

PubMed

Amino acid assimilation by different representatives of Mycoplasma genus has been investigated. All typical strains, involved in this research--Mycoplasma pneumoniae, M. capricolum, M. hominis, M. mycoides subsp. capri, M. fermentans, M. salivarium were able to assimilate asparagine, glutamine, threonine, histidine and tryptophan. Most of the investigated mycoplasmas were able to assimilate proline, phenylalanine, methionine, glutamate, lysine, serine, tyrosine, glycine, valine, isoleucine and alanine; assimilation of leucine and cysteine was observed rarely. Each of the investigated species of mycoplasmas are characterized by a specific spectrum of assimilated amino acids that can be used as additional characteristic for systematics of mollicutes. PMID:15456219

Tokovenko, I P; Malynovs'ka, L P

2004-01-01

68

Enigmatic Isovaline: Investigating the Stability, Racemization, and Formation of a Non-biological Meteoritic Amino Acid  

NASA Technical Reports Server (NTRS)

Among the Murchison meteoritic amino acids, isovaline stands out as being both nonbiological (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, the 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 D and L enantiomers. Ion-irradiated isovaline- and valinecontaining 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 undertaken experiments to synthesize 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. -- 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, AL) and the Astrobiology Analytical Laboratory (JPD, DPG) at the NASA Goddard Space Flight Center.

Hudson, Reggie; Moore, Marla; Lewis, Ariel; Dworkin, Jason

2008-01-01

69

40 CFR 721.1643 - Benzenesulfonic acid, amino substituted phenylazo-.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Benzenesulfonic acid, amino substituted phenylazo-. 721... § 721.1643 Benzenesulfonic acid, amino substituted phenylazo-. ...generically as a benzenesulfonic acid, amino substituted phenylazo-...

2011-07-01

70

40 CFR 721.1643 - Benzenesulfonic acid, amino substituted phenylazo-.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Benzenesulfonic acid, amino substituted phenylazo-. 721... § 721.1643 Benzenesulfonic acid, amino substituted phenylazo-. ...generically as a benzenesulfonic acid, amino substituted phenylazo-...

2010-07-01

71

40 CFR 721.1643 - Benzenesulfonic acid, amino substituted phenylazo-.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Benzenesulfonic acid, amino substituted phenylazo-. 721... § 721.1643 Benzenesulfonic acid, amino substituted phenylazo-. ...generically as a benzenesulfonic acid, amino substituted phenylazo-...

2013-07-01

72

40 CFR 721.1643 - Benzenesulfonic acid, amino substituted phenylazo-.  

...2014-07-01 false Benzenesulfonic acid, amino substituted phenylazo-. 721... § 721.1643 Benzenesulfonic acid, amino substituted phenylazo-. ...generically as a benzenesulfonic acid, amino substituted phenylazo-...

2014-07-01

73

40 CFR 721.1643 - Benzenesulfonic acid, amino substituted phenylazo-.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Benzenesulfonic acid, amino substituted phenylazo-. 721... § 721.1643 Benzenesulfonic acid, amino substituted phenylazo-. ...generically as a benzenesulfonic acid, amino substituted phenylazo-...

2012-07-01

74

Roast effects on coffee amino acid enantiomers  

Microsoft Academic Search

The effects of roast on the amino acid enantiomers (d- and l-) of two green coffee samples (arabica and robusta) were determined, by gas chromatography, on a Chirasil l-Val column. The free amino acids were present in low amounts in both green samples and destroyed to a very high degree with roast. After hydrolysis, the amino acids behaved according to

S. Casal; E. Mendes; M. B. P. P. Oliveira; M. A. Ferreira

2005-01-01

75

Evolutionarily Conserved Optimization of Amino Acid Biosynthesis  

E-print Network

Evolutionarily Conserved Optimization of Amino Acid Biosynthesis Ethan O. Perlstein Ã? Benjamin L in evolutionary history the biosynthetic enzymes for amino acid x gradually lost residues of x, thereby reducing the threshold for deleterious effects of x scarcity. The resulting reduction in cognate amino acid composition

de Bivort, Benjamin

76

Intestinal metabolism of sulfur amino acids  

Technology Transfer Automated Retrieval System (TEKTRAN)

The gastrointestinal tract (GIT) serves a key function in the digestion of dietary protein and absorption of amino acids. However, the GIT is also an important site of amino acid metabolism in the body. Methionine is an indispensable amino acid and must be supplied in the diet. In addition, consider...

77

Amino acids in earthworms: Are earthworms ecosystemivorous?  

Microsoft Academic Search

Amino acid contents were studied in eight earthworm species (Lumbricus rubellus, L. terrestris, Nicodrilus roseus, N. caliginosus, Dendrobaena octaedra, Eisenia nordenskioldi, Octolasium lacteum, Drawida ghilarovi), plant litter and soil. There are considerable differences in the content of essential amino acids between earthworms and their food (for most amino acids, one order of magnitude; for methionine, up to two orders of

Andrei D. Pokarzhevskii; Dmitrii P. Zaboyev; Gennadii N. Ganin; Stella A. Gordienko

1997-01-01

78

21 CFR 172.320 - Amino acids.  

... 2014-04-01 2014-04-01 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...

2014-04-01

79

21 CFR 172.320 - Amino acids.  

Code of Federal Regulations, 2013 CFR

... 2013-04-01 2013-04-01 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...

2013-04-01

80

Amino acid analyses of Apollo 14 samples.  

NASA Technical Reports Server (NTRS)

Detection limits were between 300 pg and 1 ng for different amino acids, in an analysis by gas-liquid chromatography of water extracts from Apollo 14 lunar fines in which amino acids were converted to their N-trifluoro-acetyl-n-butyl esters. Initial analyses of water and HCl extracts of sample 14240 and 14298 samples showed no amino acids above background levels.

Gehrke, C. W.; Zumwalt, R. W.; Kuo, K.; Aue, W. A.; Stalling, D. L.; Kvenvolden, K. A.; Ponnamperuma, C.

1972-01-01

81

Unnatural reactive amino acid genetic code additions  

SciTech Connect

This invention provides compositions and methods for producing translational components that expand the number of genetically encoded amino acids in eukaryotic cells. The components include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, orthogonal pairs of tRNAs/synthetases and unnatural amino acids. Proteins and methods of producing proteins with unnatural amino acids in eukaryotic cells are also provided.

Deiters, Alexander; Cropp, T. Ashton; Chin, Jason W.; Anderson, J. Christopher; Schultz, Peter G.

2014-08-26

82

Unnatural reactive amino acid genetic code additions  

DOEpatents

This invention provides compositions and methods for producing translational components that expand the number of genetically encoded amino acids in eukaryotic cells. The components include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, orthogonal pairs of tRNAs/synthetases and unnatural amino acids. Proteins and methods of producing proteins with unnatural amino acids in eukaryotic cells are also provided.

Deiters, Alexander (La Jolla, CA); Cropp, T. Ashton (San Diego, CA); Chin, Jason W. (Cambridge, GB); Anderson, J. Christopher (San Francisco, CA); Schultz, Peter G. (La Jolla, CA)

2011-02-15

83

Unnatural reactive amino acid genetic code additions  

DOEpatents

This invention provides compositions and methods for producing translational components that expand the number of genetically encoded amino acids in eukaryotic cells. The components include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, pairs of tRNAs/synthetases and unnatural amino acids. Proteins and methods of producing proteins with unnatural amino acids in eukaryotic cells are also provided.

Deiters, Alexander; Cropp, Ashton T; Chin, Jason W; Anderson, Christopher J; Schultz, Peter G

2013-05-21

84

Unnatural reactive amino acid genetic code additions  

DOEpatents

This invention provides compositions and methods for producing translational components that expand the number of genetically encoded amino acids in eukaryotic cells. The components include orthogonal tRNAs, orthogonal aminoacyl-tRNAsyn-thetases, pairs of tRNAs/synthetases and unnatural amino acids. Proteins and methods of producing proteins with unnatural amino acids in eukaryotic cells are also provided.

Deiters, Alexander (La Jolla, CA); Cropp, T. Ashton (Bethesda, MD); Chin, Jason W. (Cambridge, GB); Anderson, J. Christopher (San Francisco, CA); Schultz, Peter G. (La Jolla, CA)

2011-08-09

85

Postnatal amino acid uptake by the rat small intestine. Changes in membrane transport systems for amino acids associated with maturation of jejunal morphology.  

PubMed

The uptake of a number of amino acids by the developing small intestine of the rat was investigated in vitro. L-valine, L-leucine, L-methionine, L-phenylalanine, L-arginine and L-lysine were all taken up by active transport and concentrated within the jejunal mucosa. GABA was not actively transported by the jejunum. The kinetics of carrier transport of amino acids was determined from birth to maturity. The Michaelis constant (Km) of the L-leucine, L-methionine, L-arginine and l-lysine transport systems was found to be low postnatally and increased with age, particularly after the time of weaning. The rate of l-leucine, L-methionine, L-phenylalanine and L-lysine transport (Vmax) was high postnatally but decreased after weaning. Neutral amino acids were transported at higher rates than basic amino acids. l-arginine was poorly transported by the jejunum. The specificity of transport systems for amino acids was investigated in inhibition studies. Amino acid transport systems appeared to be polyfunctional in the postnatal period but were more specific in post-weaned animals. The changes in kinetics and specificity of amino acid transport in the small intestine are discussed with reference to their possible functional significance and to the maturational changes in the jejunum, particularly with the appearance of a functionally distinct absorptive cell lining the intestinal villi during the third postnatal week (the time of weaning). PMID:121999

Murphy, S; Daniels, V G

1979-04-01

86

Up-regulating pyocyanin production by amino acid addition for early electrochemical identification of Pseudomonas aeruginosa.  

PubMed

This work focuses on developing a faster method for electrochemically detecting a Pseudomonas aeruginosa infection through the addition of amino acids to cell culture samples. We performed square-wave voltammetry measurements of pyocyanin produced by P. aeruginosa using commercially available carbon-based electrodes connected to a Ag/AgCl reference. The electrochemical response resulting from the production of pyocyanin by bacteria was measured in the presence of various amino acids while varying three different culturing parameters: liquid media type (trypticase soy broth vs. M63 minimal media); concentration of amino acids in the solution; and initial concentration of the P. aeruginosa in the solution. Our results demonstrate a faster and stronger electrochemical response in media containing tyrosine and valine at elevated concentrations, lending promise to using amino acids as up-regulatory molecules for faster bacterial detection. PMID:24998317

Sismaet, Hunter J; Webster, Thaddaeus A; Goluch, Edgar D

2014-09-01

87

Light-activated amino acid transport in Halobacterium halobium envelope vesicles  

NASA Technical Reports Server (NTRS)

Vesicles prepared from Halobacterium halobium cell envelopes accumulate amino acids in response to light-induced electrical and chemical gradients. Nineteen of 20 commonly occurring amino acids have been shown to be actively accumulated by these vesicles in response to illumination or in response to an artificially created Na+ gradient. On the basis of shared common carriers the transport systems can be divided into eight classes, each responsible for the transport of one or several amino acids: arginine, lysine, histidine; asparagine, glutamine; alanine, glycine, threonine, serine; leucine, valine, isoleucine, methionine; phenylalanine, tyrosine, tryptophan; aspartate; glutamate; proline. Available evidence suggests that these carriers are symmetrical in that amino acids can be transported equally well in both directions across the vesicle membranes. A tentative working model to account for these observations is presented.

Macdonald, R. E.; Lanyi, J. K.

1977-01-01

88

[Arachidonoyl amino acids and arachidonoyl peptides: synthesis and properties].  

PubMed

N-Arachidonoyl (AA) derivatives of amino acids (glycine, phenylalanine, proline, valine, gamma-amino butyric acid (GABA), dihydroxyphenylalanine, tyrosine, tryptophan, and alanine) and peptides (Semax, MEHFPGP, and PGP) were synthesized in order to study the biological properties of acylamino acids. The mass spectra of all the compounds at atmospheric pressure electrospray ionization display the most intense peaks of protonated molecular ions; the detection limits for these compounds are 10 fmol per sample. AA-Gly showed the highest inhibitory activity toward fatty acid amide hydrolase from rat brain (IC50 6.5 microM) among all the acylamino acids studied. AA-Phe, AA-Tyr, and AA-GABA exhibited a weak but detectable inhibitory effect (IC50 55, 60, and 50 microM, respectively). The acylated amino acids themselves, except for AA-Gly, were stable to the hydrolysis by this enzyme. All the arachidonoylamino acids inhibited cabbage phospholipase D to various degrees; AA-GABA and AA-Phe proved to be the most active (IC50 20 and 27 microM, respectively). Attempts to detect the biosynthesis of AA-Tyr in homogenates of rat liver and nerve tissue showed no formation in vitro of either this acylamino acid or AA-dopamine and AA-Phe, the products of its metabolism. The highest contents of these metabolites were detected in liver homogenate and in the brain homogenate, respectively. Acylamino acids exert no cytotoxic effect toward the glioma C6 cells. It was shown that N-acylation of Semax with arachidonic acid results in enhancement of its hydrolytic stability and increases its affinity for the sites of specific binding in rat cerebellum membranes. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2006, vol. 32, no. 3; see also http://www.maik.ru. PMID:16808168

Bezuglov, V V; Gretskaia, N M; Blazhenova, A V; Adrianova, E L; Akimov, A V; Bobrov, M Iu; Nazimov, I V; Kisel', M I; Sharko, O L; Novikov, A V; Krasnov, N V; Shevchenko, V P; V'iunova, T V; Miasoedova, N F

2006-01-01

89

Effect of defaunation and amino acid supplementation on growth and amino acid balance in growing sheep  

E-print Network

Effect of defaunation and amino acid supplementation on growth and amino acid balance in growing, and the wool growth. The supplementation with protected amino acids may increase the growth rate and may lead and the addition of protected methionine and lysine on animal growth and amino acids digestibility in the body

Paris-Sud XI, Université de

90

Current topics in the biotechnological production of essential amino acids, functional amino acids, and dipeptides.  

PubMed

Amino acids play important roles in both human and animal nutrition and in the maintenance of health. Here, amino acids are classified into three groups: first, essential amino acids, which are essential to nutrition; second, functional amino acids, recently found to be important in the promotion of physiological functions; and third, dipeptides, which are used to resolve problematic features of specific free amino acids, such as their instability or insolubility. This review focusses on recent researches concerning the microbial production of essential amino acids (lysine and methionine), functional amino acids (histidine and ornithine), and a dipeptide (L-alanyl-L-glutamine). PMID:24679256

Mitsuhashi, Satoshi

2014-04-01

91

Ion Chromatography Based Urine Amino Acid Profiling Applied for Diagnosis of Gastric Cancer  

PubMed Central

Aim. Amino acid metabolism in cancer patients differs from that in healthy people. In the study, we performed urine-free amino acid profile of gastric cancer at different stages and health subjects to explore potential biomarkers for diagnosing or screening gastric cancer. Methods. Forty three urine samples were collected from inpatients and healthy adults who were divided into 4 groups. Healthy adults were in group A (n = 15), early gastric cancer inpatients in group B (n = 7), and advanced gastric cancer inpatients in group C (n = 16); in addition, two healthy adults and three advanced gastric cancer inpatients were in group D (n = 5) to test models. We performed urine amino acids profile of each group by applying ion chromatography (IC) technique and analyzed urine amino acids according to chromatogram of amino acids standard solution. The data we obtained were processed with statistical analysis. A diagnostic model was constructed to discriminate gastric cancer from healthy individuals and another diagnostic model for clinical staging by principal component analysis. Differentiation performance was validated by the area under the curve (AUC) of receiver-operating characteristic (ROC) curves. Results. The urine-free amino acid profile of gastric cancer patients changed to a certain degree compared with that of healthy adults. Compared with healthy adult group, the levels of valine, isoleucine, and leucine increased (P < 0.05), but the levels of histidine and methionine decreased (P < 0.05), and aspartate decreased significantly (P < 0.01). The urine amino acid profile was also different between early and advanced gastric cancer groups. Compared with early gastric cancer, the levels of isoleucine and valine decreased in advanced gastric cancer (P < 0.05). A diagnosis model constructed for gastric cancer with AUC value of 0.936 tested by group D showed that 4 samples could coincide with it. Another diagnosis model for clinical staging with an AUC value of 0.902 tested by 3 advanced gastric cancer inpatients of group D showed that all could coincide with the model. Conclusions. The noticeable differences of urine-free amino acid profiles between gastric cancer patients and healthy adults indicate that such amino acids as valine, isoleucine, leucine, methionine, histidine and aspartate are important metabolites in cell multiplication and gene expression during tumor growth and metastatic process. The study suggests that urine-free amino acid profiling is of potential value for screening or diagnosing gastric cancer. PMID:22888338

Fan, Jing; Hong, Jing; Hu, Jun-Duo; Chen, Jin-Lian

2012-01-01

92

Amino Acid Properties Conserved in Molecular Evolution  

PubMed Central

That amino acid properties are responsible for the way protein molecules evolve is natural and is also reasonably well supported both by the structure of the genetic code and, to a large extent, by the experimental measures of the amino acid similarity. Nevertheless, there remains a significant gap between observed similarity matrices and their reconstructions from amino acid properties. Therefore, we introduce a simple theoretical model of amino acid similarity matrices, which allows splitting the matrix into two parts – one that depends only on mutabilities of amino acids and another that depends on pairwise similarities between them. Then the new synthetic amino acid properties are derived from the pairwise similarities and used to reconstruct similarity matrices covering a wide range of information entropies. Our model allows us to explain up to 94% of the variability in the BLOSUM family of the amino acids similarity matrices in terms of amino acid properties. The new properties derived from amino acid similarity matrices correlate highly with properties known to be important for molecular evolution such as hydrophobicity, size, shape and charge of amino acids. This result closes the gap in our understanding of the influence of amino acids on evolution at the molecular level. The methods were applied to the single family of similarity matrices used often in general sequence homology searches, but it is general and can be used also for more specific matrices. The new synthetic properties can be used in analyzes of protein sequences in various biological applications. PMID:24967708

Rudnicki, Witold R.; Mroczek, Teresa; Cudek, Pawe?

2014-01-01

93

Amino acid contents of infant foods.  

PubMed

The protein quality of three milk-cereal-based infant foods (paps) was evaluated by determining their amino acid contents and calculating the amino acid score. Proteins were subjected to acid hydrolysis, prior to which cysteine and methionine were oxidized with performic acid. Amino acids were determined by reverse-phase high-performance liquid chromatography with fluorescence detection with a prior derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate. Tryptophan was determined by reverse-phase high-performance liquid chromatography with ultraviolet detection after basic hydrolysis. Glutamic acid, proline and leucine were the most abundant amino acids, whereas tryptophan and cysteine had the lowest contents. Tryptophan was the limiting amino acid in the analyzed infant foods. A pap serving (250 ml) contributes significantly to fulfillment of the recommended dietary allowances of essential and semi-essential amino acids for infants (7-12 months old) and young children (1-3 years old). PMID:17127472

Bosch, Lourdes; Alegría, Amparo; Farré, Rosaura

2006-01-01

94

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

95

Gustatory responsiveness to the 20 proteinogenic amino acids in the spider monkey (Ateles geoffroyi).  

PubMed

The gustatory responsiveness of four adult spider monkeys to the 20 proteinogenic amino acids was assessed in two-bottle preference tests of brief duration (1min). We found that Ateles geoffroyi responded with significant preferences for seven amino acids (glycine, l-proline, l-alanine, l-serine, l-glutamic acid, l-aspartic acid, and l-lysine) when presented at a concentration of 100mM and/or 200mM and tested against water. At the same concentrations, the animals significantly rejected five amino acids (l-tryptophan, l-tyrosine, l-valine, l-cysteine, and l-isoleucine) and were indifferent to the remaining tastants. Further, the results show that the spider monkeys discriminated concentrations as low as 0.2mM l-lysine, 2mM l-glutamic acid, 10mM l-proline, 20mM l-valine, 40mM glycine, l-serine, and l-aspartic acid, and 80mM l-alanine from the alternative stimulus, with individual animals even scoring lower threshold values. A comparison between the taste qualities of the proteinogenic amino acids as described by humans and the preferences and aversions observed in the spider monkeys suggests a fairly high degree of agreement in the taste quality perception of these tastants between the two species. A comparison between the taste preference thresholds obtained with the spider monkeys and taste detection thresholds reported in human subjects suggests that the taste sensitivity of A. geoffroyi for the amino acids tested here might match that of Homo sapiens. The results support the assumption that the taste responses of spider monkeys to proteinogenic amino acids might reflect an evolutionary adaptation to their frugivorous and thus protein-poor diet. PMID:24480073

Larsson, Jenny; Maitz, Anna; Hernandez Salazar, Laura Teresa; Laska, Matthias

2014-03-29

96

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. PMID:6481334

1984-01-01

97

Enantiomeric excesses in meteoritic amino acids  

NASA Technical Reports Server (NTRS)

Gas chromatographic-mass spectral analyses of the four stereoisomers of 2-amino-2,3-dimethylpentanoic acid (dl-alpha-methylisoleucine and dl-alpha-methylalloisoleucine) obtained from the Murchison meteorite show that the L enantiomer occurs in excess (7.0 and 9.1%, respectively) in both of the enantiomeric pairs. Similar results were obtained for two other alpha-methyl amino acids, isovaline and alpha-methylnorvaline, although the alpha hydrogen analogs of these amino acids, alpha-amino-n-butyric acid and norvaline, were found to be racemates. With the exception of alpha-amino-n-butyric acid, these amino acids are either unknown or of limited occurrence in the biosphere. Because carbonaceous chondrites formed 4.5 billion years ago, the results are indicative of an asymmetric influence on organic chemical evolution before the origin of life.

Cronin, J. R.; Pizzarello, S.

1997-01-01

98

Indigenous amino acids in primitive CR meteorites  

E-print Network

CR meteorites are among the most primitive meteorites. In this paper, we report the first measurements of amino acids in Antarctic CR meteorites, two of which show the highest amino acid concentrations ever found in a chondrite. EET92042, GRA95229 and GRO95577 were analyzed for their amino acid content using high performance liquid chromatography with UV fluorescence detection (HPLC-FD) and gas chromatographymass spectrometry (GC-MS). Our data show that EET92042 and GRA95229 are the most amino acid-rich chondrites ever analyzed, with total amino acid concentrations ranging from 180 parts-per-million (ppm) to 249 ppm. GRO95577, however, is depleted in amino acids. The most abundant amino acids present in the EET92042 and GRA95229 meteorites are the alpha-amino acids glycine, isovaline, alpha-aminoisobutyric acid (alpha-AIB), and alanine, with delta13C values ranging from +31.6per mil to +50.5per mil. The carbon isotope results together with racemic enantiomeric ratios determined for most amino acids strongly indicate an extraterrestrial origin of these compounds. In addition, the relative abundances of alpha-AIB and beta-alanine in the Antarctic CR meteorites analyzed appear to correspond to the degree of aqueous alteration on their respective parent body.

Z. Martins; C. M. O'D. Alexander; G. E. Orzechowska; M. L. Fogel; P. Ehrenfreund

2008-03-10

99

Semantic Publishing of Knowledge about Amino Acids  

E-print Network

Abstract. We semantically publish knowledge about the amino acids commonly described within biochemistry. We do this as an ontology written in OWL and presented as XML/RDF. The classification of amino acids is based on taylor’s article (PMID:3461222) from 1986 published in the Journal of Theoretical Biology. The ontology goes further than the static paper version; it combines many aspects of the physicochemical properties taylor uses to classify amino acids to give a rich, multi axial classification of amino acids. Taylor’s original description of the amino acid’s physicochemical properties are captured with value partitions and restrictions on the amino acid classes themselves. A series of defined classes then establishes the multi-axial classification. The publication, hwen loaded into an OWL ontology manipulation tool, allows some knowledge about amino acids to be explored and used computationally. By publishing this knowledge about amino acids as a semantic document in the form of an ontology we persue an agenda of disruptive technology in publishing. It allows us to ‘push ’ at the nature of a semantic publication. Blogs about the published semantics of amino acids may be found at

Robert Stevens; Phillip Lord

100

Indigenous amino acids in primitive CR meteorites  

E-print Network

CR meteorites are among the most primitive meteorites. In this paper, we report the first measurements of amino acids in Antarctic CR meteorites, two of which show the highest amino acid concentrations ever found in a chondrite. EET92042, GRA95229 and GRO95577 were analyzed for their amino acid content using high performance liquid chromatography with UV fluorescence detection (HPLC-FD) and gas chromatographymass spectrometry (GC-MS). Our data show that EET92042 and GRA95229 are the most amino acid-rich chondrites ever analyzed, with total amino acid concentrations ranging from 180 parts-per-million (ppm) to 249 ppm. GRO95577, however, is depleted in amino acids. The most abundant amino acids present in the EET92042 and GRA95229 meteorites are the alpha-amino acids glycine, isovaline, alpha-aminoisobutyric acid (alpha-AIB), and alanine, with delta13C values ranging from +31.6per mil to +50.5per mil. The carbon isotope results together with racemic enantiomeric ratios determined for most amino acids strongly i...

Martins, Z; Orzechowska, G E; Fogel, M L; Ehrenfreund, P

2008-01-01

101

Amino acids in the Tagish Lake Meteorite  

NASA Technical Reports Server (NTRS)

High-performance liquid chromatography (HPLC) based amino acid analysis of a Tagish Lake meteorite sample recovered 3 months after the meteorite fell to Earth have revealed that the amino acid composition of Tagish Lake is strikingly different from that of the CM and CI carbonaceous chondrites. We found that the Tagish Lake meteorite contains only trace levels of amino acids (total abundance = 880 ppb), which is much lower than the total abundance of amino acids in the CI Orgueil (4100 ppb) and the CM Murchison (16 900 ppb). Because most of the same amino acids found in the Tagish Lake meteorite are also present in the Tagish Lake ice melt water, we conclude that the amino acids detected in the meteorite are terrestrial contamination. We found that the exposure of a sample of Murchison to cold water lead to a substantial reduction over a period of several weeks in the amount of amino acids that are not strongly bound to the meteorite matrix. However, strongly bound amino acids that are extracted by direct HCl hydrolysis are not affected by the leaching process. Thus even if there had been leaching of amino acids from our Tagish Lake meteorite sample during its 3 month residence in Tagish Lake ice and melt water, a Murchison type abundance of endogenous amino acids in the meteorite would have still been readily detectable. The low amino acid content of Tagish Lake indicates that this meteorite originated fiom a different type of parent body than the CM and CI chondrites. The parent body was apparently devoid of the reagents such as aldehyldes/ketones, HCN and ammonia needed for the effective abiotic synthesis of amino acids. Based on reflectance spectral measurements, Tagish Lake has been associated with P- or D-type asteroids. If the Tagish Lake meteorite was indeed derived fiom these types of parent bodies, our understanding of these primitive asteroids needs to be reevaluated with respect to their potential inventory of biologically important organic compounds.

Kminek, G.; Botta, O.; Glavin, D. P.; Bada, J. L.

2002-01-01

102

Amino acids precursors in lunar finds  

NASA Technical Reports Server (NTRS)

The consistent pattern is discussed of amino acids found in lunar dust from Apollo missions. The evidence indicates that compounds yielding amino acids were implanted into the surface of the moon by the solar wind, and the kind and amounts of amino acids found on the moon are closely similar to those found in meteorites. It is concluded that there is a common cosmochemical pattern for the moom and meteorites, and this offers evidence of a common course of cosmochemical reactions for carbon.

Fox, S. W.; Harada, K.; Hare, P. E.; Hinsch, G.; Mueller, G.

1975-01-01

103

Relationship between amino acid usage and amino acid evolution in primates.  

PubMed

Amino acid usage varies from species to species. A previous study has found a universal trend in amino acid gain and loss in many taxa and a one-way model of amino acid evolution in which the number of new amino acids increases as the number of old amino acids decreases was proposed. Later studies showed that this pattern of amino acid gain and loss is likely to be compatible with the neutral theory. The present work aimed to further study this problem by investigating the evolutionary patterns of amino acids in 8 primates (the nucleotide and protein alignments are available online http://gattaca.nju.edu.cn/pub_data.html). First, the number of amino acids gained and lost was calculated and the evolution trend of each amino acid was inferred. These values were found to be closely related to the usage of each amino acid. Then we analyzed the mutational trend of amino acid substitution in human using SNPs, this trend is highly correlated with fixation trend only with greater variance. Finally, the trends in the evolution of 20 amino acids were evaluated in human on different time scales, and the increasing rate of 5 significantly increasing amino acids was found to decrease as a function of time elapsed since divergence, and the dS/dN ratio also found to increase as a function of time elapsed since divergence. These results suggested that the observed amino acid substitution pattern is influenced by mutation and purifying selection. In conclusion, the present study shows that usage of amino acids is an important factor capable of influencing the observed pattern of amino acid evolution, and also presented evidences suggesting that the observed universal trend of amino acid gain and loss is compatible with neutral evolution. PMID:25527119

Liu, Haoxuan; Xie, Zhengqing; Tan, Shengjun; Zhang, Xiaohui; Yang, Sihai

2015-02-25

104

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. PMID:14047225

Hardman, John K.; Stadtman, Thressa C.

1963-01-01

105

Erythrocytes participate significantly in blood transport of amino acids during the post absorptive state in normal humans.  

PubMed

To investigate the participation of erythrocytes in the blood transport of amino acids during the course of intestinal absorption in humans, erythrocyte and plasma amino-acid concentrations were determined following ingestion of an oral load of amino acids. In addition to baseline plasma and erythrocyte amino acid concentrations in 18 subjects, plasma and erythrocyte amino acids kinetics during the 125 min following an oral amino acid load were further determined in 9 of the 18 subjects. The results showed that human erythrocytes contained most amino acids at similar or higher concentrations than plasma. Furthermore, the correlations observed between plasma and erythrocyte contents clearly indicated that erythrocytes were involved in the transport of amino acids by the blood. For some amino acids erythrocyte transport sometimes exceeded that of plasma. Significant correlation coefficients showed that strong plasma-erythrocyte relationships existed for alanine, valine, methionine, isoleucine, leucine, phenylalanine, and ornithine. In conclusion, our data supported the hypothesis that both blood compartments, plasma and erythrocytes, are involved significantly in the blood transport of amino acids in humans during the postabsorptive state. PMID:9840404

Agli, A N; Schaefer, A; Geny, B; Piquard, F; Haberey, P

1998-11-01

106

Alteration of free serum amino acids in voles infected with Trypanosoma brucei gambiense.  

PubMed

Free serum amino acid pools of field voles, Microtus montanus, were determined over a 24 hr period, and compared to values obtained from voles infected with Trypanosoma brucei gambiense. The majority of amino acids in the control animals demonstrated a diurnal variation, peaking predominantly during the dark portion of the photoperiod. This trend was not evident in the infected animals. In addition, infected voles possessed an apparent state of hypoaminoacidemia, with levels of threonine, serine, valine, isoleucine, leucine, tryosine, and tryptophan typically below uninfected values. Alanine and proline, in contrast, were markedly increased at certain time points. Tyrosine (reduced by approximately 50%) and tryptophan (reduced to levels below detection) underwent the most pronounced drop in trypanosome-infected animals, indicating the possibility of a related alteration in pools of derivative biogenic amines in other tissues. This suggests a role for the latter 2 amino acids in the neuropsychiatric syndromes of African trypanosomiasis. PMID:321737

Newport, G R; Page, C R; Ashman, P U; Stibbs, H H; Seed, J R

1977-02-01

107

Gluconeogenesis from Amino Acids in Germinating Castor Bean Endosperm and its Role in Transport to the Embryo 1  

PubMed Central

During germination of the castor bean all of the contents of the endosperm are ultimately transported to the embryo through the cotyledon or respired. A net loss of nitrogen from the endosperm begins about the fourth day, i.e. at the time when embryo growth and fat breakdown are also beginning. Amino acid analysis of the exudate from the cotyledons, still enclosed in the endosperm, showed that the amounts of aspartate, glutamate, glycine, and alanine were very low and that glutamine made up 40% of the amino acids in the exudate. Amino acids labeled with 14C were applied to intact excised endosperms to follow utilization. Aspartate, glutamate, alanine, glycine, serine, and leucine were converted to sugar to varying extents. Proline, arginine, valine, and phenylalanine were not appreciably converted to sugars. Proline and glutamate were converted to glutamine. When 14C-glutamate, aspartate, and alanine were added to the outer endosperm of intact seedlings, only sugars and glutamine contained appreciable label in the exudate. When 14C-valine was added, it was virtually the only labeled compound in the exudate. The results show that amino acids which on deamination can give rise to intermediates in the pathway of conversion of fat to sucrose are largely converted to sucrose and the nitrogen transported as glutamine. Other amino acids released from the endosperm protein are transported intact into the seedling axis. Some carbon from the gluconeogenic amino acids is also transported as glutamine. PMID:16656694

Stewart, Cecil R.; Beevers, Harry

1967-01-01

108

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

2014-02-01

109

Incorporation of [3H]Leucine and [3H]Valine into Protein of Freshwater Bacteria: Field Applications  

PubMed Central

Incorporation of leucine and valine into proteins of freshwater bacteria as a measure of bacterial production was tested in two eutrophic Danish lakes and was related to bacterial production measured by thymidine incorporation. In a depth profile (0 to 8 m) in Frederiksborg Castle Lake, incorporation of 100 nM leucine and valine gave similar rates of protein production. In terms of carbon, this production was about 50% lower than incorporation of 10 nM thymidine. In another depth profile in the same lake, incorporations of 10 nM valine and 100 nM leucine were identical, but differed from incorporations of 10 nM leucine and 100 nM valine. Bacterial carbon production calculated from incorporations of 10 nM thymidine and 10 nM leucine was similar, whereas 10 nM valine and 100 nM leucine and valine indicated an up to 2.4-fold-higher rate of carbon production. In a diel study in Lake Bagsvaerd, incorporation of 100 nM leucine and valine indicated a similar protein production, but the calculated carbon production was about 1.9-fold higher than the production based on uptake of 10 nM thymidine. Different diel changes in incorporation of the two amino acids and in incorporation of thymidine were observed. In both lakes, concentrations of naturally occurring leucine and valine were <5 nM in most samples. This means that the specific activity of a 3H isotope added at a concentration of 100 nM usually was diluted a maximum of 5%. Net assimilation of natural free amino acids in the lakes sustained 8 to 69% of the net bacterial carbon requirement, estimated from incorporation of leucine, valine, or thymidine. The present results indicate that incorporation of leucine and valine permits realistic measurements of bacterial production in freshwater environments. PMID:16348808

Jørgensen, Niels O. G.

1992-01-01

110

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. PMID:23094070

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

2012-01-01

111

Research for amino acids in lunar samples.  

NASA Technical Reports Server (NTRS)

The study was primarily directed toward the examination of Apollo 14 lunar fines for indigenous amino acids or materials which could be converted to amino acids on hydrolysis with 6 N hydrochloric acid. Initial experiments were conducted to confirm the integrity of the derivatization reactions and reagents, and to optimize the gas-liquid chromatographic (GLC) instrumental and chromatographic system for the separation and flame ionization detection of the amino acid derivatives. In studies on the recovery of amino acids added to lunar fines, low recoveries were obtained when 10 ng of each amino acid were added to 50 mg of virgin fines, but the subsequent addition of 50 ng of each to the previously extracted sample resulted in much higher recoveries.

Gehrke, C. W.; Zumwalt, R. W.; Kuo, K.; Rash, J. J.; Aue , W. A.; Stalling, D. L.; Kvenvolden, K. A.; Ponnamperuma, C.

1972-01-01

112

Amino acid regulation of gene expression.  

PubMed Central

The impact of nutrients on gene expression in mammals has become an important area of research. Nevertheless, the current understanding of the amino acid-dependent control of gene expression is limited. Because amino acids have multiple and important functions, their homoeostasis has to be finely maintained. However, amino-acidaemia can be affected by certain nutritional conditions or various forms of stress. It follows that mammals have to adjust several of their physiological functions involved in the adaptation to amino acid availability by regulating the expression of numerous genes. The aim of the present review is to examine the role of amino acids in regulating mammalian gene expression and protein turnover. It has been reported that some genes involved in the control of growth or amino acid metabolism are regulated by amino acid availability. For instance, limitation of several amino acids greatly increases the expression of the genes encoding insulin-like growth factor binding protein-1, CHOP (C/EBP homologous protein, where C/EBP is CCAAT/enhancer binding protein) and asparagine synthetase. Elevated mRNA levels result from both an increase in the rate of transcription and an increase in mRNA stability. Several observations suggest that the amino acid regulation of gene expression observed in mammalian cells and the general control process described in yeast share common features. Moreover, amino acid response elements have been characterized in the promoters of the CHOP and asparagine synthetase genes. Taken together, the results discussed in the present review demonstrate that amino acids, by themselves, can, in concert with hormones, play an important role in the control of gene expression. PMID:10998343

Fafournoux, P; Bruhat, A; Jousse, C

2000-01-01

113

Valine needs of male broilers from 42 to 56 days of age.  

PubMed

An experiment was conducted using Ross x Ross 308 males to estimate the proportion of dietary valine needed to optimize performance in broilers from 42 to 56 d of age. All birds received common feeds from 0 to 42 d, and then experimental diets were given to 56 d of age. A diet consisting of corn, soybean meal, and corn gluten meal (17% CP, 3.25 kcal of ME/g) having 0.60% valine served as basal feed. All other essential amino acids were above recommended levels. Successive additions of 0.07% of L-valine were isonitrogenously substituted for L-glutamic acid up to a total of 0.81%. Regression analysis (95% of response) indicated that valine at 0.72% of the diet maximized body weight gain, whereas 0.73% optimized feed conversion. Depot fat removed from the abdominal cavity after processing was unaltered, and weights of resultant chilled carcasses maximized at 0.73% valine in parallel with final live weight. The amount of fillets recovered from chilled carcasses optimized at 0.73% valine; however, the incidence of distinctive blood streaks in the meat (splash) progressively increased with valine as did the level of redness apart from streaking, based on light reflectance. Given lysine at 0.85%, a ratio of 0.86 with valine appears to be adequate. The presently determined requirement of 0.73% total valine (0.67% digestible) for broiler males from 42 to 56 d of age is slightly higher than the 0.70% recommended by the NRC. PMID:15206621

Corzo, A; Moran, E T; Hoehler, D

2004-06-01

114

The Apollo Program and Amino Acids  

ERIC Educational Resources Information Center

Discusses the determination of hydrolyzable amino acid precursors and a group of six amino acids in the returned lunar samples of the Apollo programs. Indicates that molecular evolution is arrested at the precursor stage on the Moon because of lack of water. (CC)

Fox, Sidney W.

1973-01-01

115

Inhibitors of Aromatic Amino Acid Biosynthesis  

NSDL National Science Digital Library

This lesson will detail the biochemical mechanisms that are affected by herbicides which inhibit a plantâ??s ability to synthesize amino acids. The significance of amino acids and proteins will also be described. The herbicide glyphosate, will be studied at length, including the advances made by biotechnology.

116

6th Amino Acid Assessment Workshop  

Technology Transfer Automated Retrieval System (TEKTRAN)

The focus of the 6th workshop is on lysine, arginine, and related amino acids. Functions, metabolic pathways, clinical uses, and upper tolerance intakes are emphasized in the articles that follow. Lysine is arguably the most deficient amino acid in the food supply of countries where poverty exists, ...

117

Amino acid and albumin losses during hemodialysis  

Microsoft Academic Search

Amino acid and albumin losses during hemodialysis. Protein and calorie malnutrition are prevalent in chronic hemodialysis (HD) patients and has been linked to increased mortality and morbidity in this patient population, Concern has been raised that the open pore structure of high flux membranes may induce the loss of more amino acids (AA) compared to low flux membranes. To address

T Alp Ikizler; Paul J Flakoll; Robert A Parker; Raymond M Hakim

1994-01-01

118

AMINO ACID REQUIREMENTS FOR MICROBIAL PROTEIN SYNTHESIS  

E-print Network

AMINO ACID REQUIREMENTS FOR MICROBIAL PROTEIN SYNTHESIS Jane LEIBHOLZ, R.C. KELLAWAY Department if a source of dietary amino acid was required to obtain a maximum effi- ciency of protein synthesis microbial protein synthesis in the rumen. #12;References FAICHNEY G.J., 1975. In Digestion and Metabolism

Paris-Sud XI, Université de

119

D-AMINO ACID OXIDASE IN LEUKOCYTES: A POSSIBLE D-AMINO-ACID-LINKED ANTIMICROBIAL SYSTEM*  

PubMed Central

D-Amino acid oxidase has been identified within the granule fraction of human neutrophilic leukocytes. Leukocyte homogenates and purified kidney D-amino acid oxidase can utilize either isolated D-amino acids or some species of bacteria as substrates for the generation of hydrogen peroxide. When linked to leukocyte myeloperoxidase in vitro, purified D-amino acid oxidase constitutes a system lethal for certain bacteria. It is proposed that leukocyte D-amino acid oxidase and myeloperoxidase constitute a biochemically specific system for the recognition and killing of certain microorganisms. PMID:4389749

Cline, Martin J.; Lehrer, Robert I.

1969-01-01

120

Enzymatic aminoacylation of tRNA with unnatural amino acids  

E-print Network

Enzymatic aminoacylation of tRNA with unnatural amino acids Matthew C. T. Hartman, KristopherRNAs with amino acids. We have developed an AARS assay based on mass spectrometry that can be used to rapidly functional properties. Remarkably, many -amino acids, N-methyl amino acids, and , -disubstituted amino acids

Heller, Eric

121

Amino Acid Homeostasis and Chronological Longevity in Saccharomyces cerevisiae  

E-print Network

Chapter 8 Amino Acid Homeostasis and Chronological Longevity in Saccharomyces cerevisiae John P is amino acid homeostasis. Amino acid homeostasis requires three principal functions: amino acid uptake, de novo synthesis, and recycling. Autophagy plays a key role in recycling amino acids and other metabolic

Aris, John P.

122

Exogenous amino acids as fuel in shock.  

PubMed

It has been suggested that in shock branched-chain amino acids are preferentially oxidized resulting in continued proteolysis and stimulated gluconeogenesis. To determine if exogenous amino acids could be used as fuel in shock, dogs rendered hypotensive by controlled cardiac tamponade and normotensive controls were infused with amino acid mixtures and individual amino acids. When Nephramine, a mixture rich in branched-chain amino acids, was infused, plasma alpha-amino nitrogen levels rose but urea output did not increase in either the control state or in shock, suggesting that these amino acids were not rapidly deaminated to serve as fuels. Travasol, which in addition contained large amounts of alanine and glycine, tripled urea output in the controls and doubled it in shock. The limit of urea production was reached in both groups at 35 mumoles urea/minute/kg. In the Travasol-infused animals plasma alpha-amino nitrogen levels were maintained in normotension but rose sharply in shock. When glycine alone was infused into five dogs in shock urea production rate was 30.6 + 2.1 mumoles/minute/kg; with alanine the same value was 22.5 + 2.2 mumoles/minute/kg. In both cases plasma alpha-amino nitrogen levels were high, suggesting that transport of these amino acids into the cell was slow in shock. In four dogs in shock glycine-14C was added to the glycine infusate as a tracer. At radioactive equilibrium 28% of the label infused appeared in CO2; another 22% appeared in glucose. It is concluded that of all the amino acids tested only glycine and alanine are deaminated rapidly enough to serve as exogenous fuels in shock. PMID:6814205

Daniel, A M; Kapadia, B; MacLean, L D

1982-01-01

123

Influence of leucine on arterial concentrations and regional exchange of amino acids in healthy subjects.  

PubMed

1. L-Leucine was given to healthy, post-absorptive subjects as a continuous intravenous infusion (300 mumol/min) during 2 1/2 h. Arterial blood concentrations and regional exchange amino acids were measured across the splanchnic region, the brain and a leg, by the catheter technique. Renal clearance of amino acids was also determined. 2. During the infusion of leucine its concentration rose four- to six-folds, while the concentrations of several other amino acids declined continually, the effect being most pronounced for isoleucine (-55% of initial value), methionine (-55%), valine (-40%), tyrosine (-35%) and phenylalanine (-35%). 3. The infused leucine was taken up by muscle tissue (55%), by the splanchnic region (25%) and by the brain (10%). Neither leg-muscle release nor splanchnic uptake of aromatic amino acids was affected. Renal clearance and tubular reabsorption of amino acids were uninfluenced by leucine infusion. The uptake of isoleucine and methionine by the brain, seen in the basal state, was inhibited during leucine infusion. 4. The marked reduction in the concentrations of the aromatic amino acids, the uptake of leucine by the brain and the inhibition of brain methionine uptake, which accompany leucine infusion in healthy subjects, may be of relevance for the treatment of patients with portal-systemic encephalopathy. PMID:7428288

Hagenfeldt, L; Eriksson, S; Wahren, J

1980-09-01

124

The mitochondrial branched-chain aminotransferase (AtBCAT-1) is capable to initiate degradation of leucine, isoleucine and valine in almost all tissues in Arabidopsis thaliana  

Microsoft Academic Search

Plants are capable to de novo synthesize the essential amino acids leucine, isoleucine and valine. Studies in recent years, however, also revealed that plants have the potential to degrade leucine or may be all of the branched-chain amino acids. One of the enzymes participating in both biosynthesis and degradation is the branched-chain aminotransferase, which is in Arabidopsis thaliana encoded by

Joachim Schuster; Stefan Binder

2005-01-01

125

Preparation of some amino phosphonic acids  

E-print Network

also stated that phosphonation of an ester of a-amino-(3-chloropropionic acid hydrochloride with a di? alkyl sodiophosphonate gave the triester of the desired acid. Again, he gave no experimental procedure except that twice the theoretical amount... hydrochloride (XVI), This hydrochloride is not very stable, since evaporation of the hydrochloric acid solution tends to convert some of it to the free amino phosphonic acid0 HpO,HCl 2 rv ? ------ S. CHo-P(0H)oI d d NH2-HC1 XVI The free amino phosphonic...

Chambers, James Richard

1958-01-01

126

Determination of the D and L isomers of some protein amino acids present in soils  

NASA Technical Reports Server (NTRS)

The D and L isomers of some protein amino acids present in soils were measured by using a gas chromatographic technique. The results of two processing procedures were compared to determine the better method. Results of the comparison indicated that the determination of D and L percentages requires amino acid purification if one is to obtain accurate data. It was found that very significant amounts of D-alanine, D-aspartic acid, and D-glutamic acid were present in the contemporary soils studied. Valine, isoleucine, leucine, proline, and phenylalanine generally contained only a trace to very small amounts of the D isomer. It is probable that the D-amino acids from the alanine, aspartic, and glutamic acids are contributed to the soil primarily via microorganisms. The finding of very significant quantities of some D-amino acids (about 5-16%) in present-day soils may alert some investigators of geological sediments to a possible problem in using amino acid racemization as an age-dating technique.

Pollock, G. E.; Cheng, C.-N.; Cronin, S. E.

1977-01-01

127

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. PMID:12879880

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

2003-01-01

128

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

129

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

130

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

131

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

132

Branched chain amino acid metabolism profiles in progressive human nonalcoholic fatty liver disease.  

PubMed

Nonalcoholic fatty liver disease (NAFLD) is a globally widespread disease of increasing clinical significance. The pathological progression of the disease from simple steatosis to nonalcoholic steatohepatitis (NASH) has been well defined, however, the contribution of altered branched chain amino acid metabolomic profiles to the progression of NAFLD is not known. The three BCAAs: leucine, isoleucine and valine are known to mediate activation of several important hepatic metabolic signaling pathways ranging from insulin signaling to glucose regulation. The purpose of this study is to profile changes in hepatic BCAA metabolite levels with transcriptomic changes in the progression of human NAFLD to discover novel mechanisms of disease progression. Metabolomic and transcriptomic data sets representing the spectrum of human NAFLD (normal, steatosis, NASH fatty, and NASH not fatty livers) were utilized for this study. During the transition from steatosis to NASH, increases in the levels of leucine (127 % of normal), isoleucine (139 %), and valine (147 %) were observed. Carnitine metabolites also exhibited significantly elevated profiles in NASH fatty and NASH not fatty samples and included propionyl, hexanoyl, lauryl, acetyl and butyryl carnitine. Amino acid and BCAA metabolism gene sets were significantly enriched among downregulated genes during NASH. These cumulative alterations in BCAA metabolite and amino acid metabolism gene profiles represent adaptive physiological responses to disease-induced hepatic stress in NASH patients. PMID:25534430

Lake, April D; Novak, Petr; Shipkova, Petia; Aranibar, Nelly; Robertson, Donald G; Reily, Michael D; Lehman-McKeeman, Lois D; Vaillancourt, Richard R; Cherrington, Nathan J

2015-03-01

133

Amino Acid Profile in Oral Submucous Fibrosis: A High Performance Liquid Chromatography (HPLC) Study  

PubMed Central

Background: Collagen is a significant structural protein, the integrity of which is essential to be maintained for proper homeostasis. Oral submucous fibrosis (OSMF), being a collagen metabolic disorder, may be subject to changes in amino acid profiling. Aim: The present study was attempted to evaluate the amino acid profile to assess its feasibility as a biological marker in OSMF. Materials and Methods: The study group comprised of 13 patents with OSMF and the normal group comprised of 13 normal patients without associated habits or systemic disorders. Venous blood was collected from the antecubital vein, plasma was separated and the plasma was then subjected to high profile liquid chromatographic analysis. Results: The assay levels of threonine, alanine and tyrosine did not yield any significant results. The decreased assay levels of valine, Isoleucine and the increased assay level of methionine and glycine observed in group II yielded significant results in correlation with the control group. The decreased assay level seen in phenylalanine in group II and III in correlation with group IV is statistically significant. Conclusion: A few amino acids have been identified which can be used as biological markers for the severity of the disease such as valine, methionine and phenyl alanine. Large scale studies are required to elucidate the potential of these biological markers.

Goel, Richa; Chandrasekhar, Thiruvengadam; Ramani, Pratibha; Sherlin, Herald J.; Natesan, Anuja; Premkumar, Priya

2014-01-01

134

Branched-chain and aromatic amino acid catabolism into aroma volatiles in Cucumis melo L. fruit  

PubMed Central

The unique aroma of melons (Cucumis melo L., Cucurbitaceae) is composed of many volatile compounds biosynthetically derived from fatty acids, carotenoids, amino acids, and terpenes. Although amino acids are known precursors of aroma compounds in the plant kingdom, the initial steps in the catabolism of amino acids into aroma volatiles have received little attention. Incubation of melon fruit cubes with amino acids and ?-keto acids led to the enhanced formation of aroma compounds bearing the side chain of the exogenous amino or keto acid supplied. Moreover, L-[13C6]phenylalanine was also incorporated into aromatic volatile compounds. Amino acid transaminase activities extracted from the flesh of mature melon fruits converted L-isoleucine, L-leucine, L-valine, L-methionine, or L-phenylalanine into their respective ?-keto acids, utilizing ?-ketoglutarate as the amine acceptor. Two novel genes were isolated and characterized (CmArAT1 and CmBCAT1) encoding 45.6?kDa and 42.7?kDa proteins, respectively, that displayed aromatic and branched-chain amino acid transaminase activities, respectively, when expressed in Escherichia coli. The expression of CmBCAT1 and CmArAT1 was low in vegetative tissues, but increased in flesh and rind tissues during fruit ripening. In addition, ripe fruits of climacteric aromatic cultivars generally showed high expression of CmBCAT1 and CmArAT1 in contrast to non-climacteric non-aromatic fruits. The results presented here indicate that in melon fruit tissues, the catabolism of amino acids into aroma volatiles can initiate through a transamination mechanism, rather than decarboxylation or direct aldehyde synthesis, as has been demonstrated in other plants. PMID:20065117

Gonda, Itay; Bar, Einat; Portnoy, Vitaly; Lev, Shery; Burger, Joseph; Schaffer, Arthur A.; Tadmor, Ya'akov; Gepstein, Shimon; Giovannoni, James J.; Katzir, Nurit; Lewinsohn, Efraim

2010-01-01

135

Oral branched-chain amino acids decrease whole-body proteolysis  

NASA Technical Reports Server (NTRS)

BACKGROUND: This study reports the effects of ingesting branched-chain amino acids (leucine, valine, and isoleucine) on protein metabolism in four men. METHODS: To calculate leg protein synthesis and breakdown, we used a new model that utilized the infusion of L-[ring-13C6]phenylalanine and the sampling of the leg arterial-venous difference and muscle biopsies. In addition, protein-bound enrichments provided for the direct calculation of muscle fractional synthetic rate. Four control subjects ingested an equivalent amount of essential amino acids (threonine, methionine, and histidine) to discern the effects of branched-chain amino acid nitrogen vs the effects of essential amino acid nitrogen. Each drink also included 50 g of carbohydrate. RESULTS: Consumption of the branched-chain and the essential amino acid solutions produced significant threefold and fourfold elevations in their respective arterial concentrations. Protein synthesis and breakdown were unaffected by branched-chain amino acids, but they increased by 43% (p < .05) and 36% (p < .03), respectively, in the group consuming the essential amino acids. However, net leg balance of phenylalanine was unchanged by either drink. Direct measurement of protein synthesis by tracer incorporation into muscle protein (fractional synthetic rate) revealed no changes within or between drinks. Whole-body phenylalanine flux was significantly suppressed by each solution but to a greater extent by the branched-chain amino acids (15% and 20%, respectively) (p < .001). CONCLUSIONS: These results suggest that branched-chain amino acid ingestion suppresses whole-body proteolysis in tissues other than skeletal muscle in normal men.

Ferrando, A. A.; Williams, B. D.; Stuart, C. A.; Lane, H. W.; Wolfe, R. R.

1995-01-01

136

Enantiomer-specific selection of amino acids.  

PubMed

Dietary intake of L-amino acids impacts on several physiological functions, including the control of gastrointestinal motility, pancreatic secretion, and appetite. However, the biological mechanisms regulating behavioral predilections for certain amino acid types remain poorly understood. We tested the hypothesis that, in mice, the potency with which a given glucogenic amino acid increases glucose utilization reflects its rewarding properties. We have found that: (1) during long-, but not short-, term preference tests, L-alanine and L-serine were preferred over their D-enantiomer counterparts, while no such effect was observed for L-threonine vs. D-threonine; (2) these behavioral patterns were closely associated with the ability of L-amino acids to promote increases in respiratory exchange ratios such that those, and only those, L-amino acids able to promote increases in respiratory exchange ratios were preferred over their D-isomers; (3) these behavioral preferences were independent of gustatory influences, since taste-deficient Trpm5 knockout mice displayed ingestive responses very similar to those of their wild-type counterparts. We conclude that the ability to promote increases in respiratory exchange ratios enhances the reward value of nutritionally relevant amino acids and suggest a mechanistic link between substrate utilization and amino acid preferences. PMID:24072505

Ren, Xueying; Tellez, Luis A; de Araujo, Ivan E

2013-12-01

137

Distribution of Amino Acids in Lunar Regolith  

NASA Technical Reports Server (NTRS)

One of the most eagerly studied questions upon initial return of lunar samples was whether significant amounts of organic compounds, including amino acids, were present. Analyses during the 1970s produced only tentative and inconclusive identifications of indigenous amino acids. Those analyses were hampered by analytical difficulties including relative insensitivity to certain compounds, the inability to separate chiral enantiomers, and the lack of compound-specific isotopic measurements, which made it impossible to determine whether the detected amino acids were indigenous to the lunar samples or the results of contamination. Numerous advances have been made in instrumentation and methodology for amino acid characterization in extraterrestrial samples in the intervening years, yet the origin of amino acids in lunar regolith samples has been revisited only once for a single lunar sample, (3) and remains unclear. Here, we present initial data from the analyses of amino acid abundances in 12 lunar regolith samples. We discuss these abundances in the context of four potential amino acid sources: (1) terrestrial biological contamination; (2) contamination from lunar module (LM) exhaust; (3) derivation from solar windimplanted precursors; and (4) exogenous delivery from meteorites.

Elsila, J. E.; Callahan, M. P.; Glavin, D. P.; Dworkin, J. P.; Noble, S. K.; Gibson, E. K., Jr.

2014-01-01

138

Amino Acid Metabolism Conflicts with Protein Diversity  

PubMed Central

The 20 protein-coding amino acids are found in proteomes with different relative abundances. The most abundant amino acid, leucine, is nearly an order of magnitude more prevalent than the least abundant amino acid, cysteine. Amino acid metabolic costs differ similarly, constraining their incorporation into proteins. On the other hand, a diverse set of protein sequences is necessary to build functional proteomes. Here, we present a simple model for a cost-diversity trade-off postulating that natural proteomes minimize amino acid metabolic flux while maximizing sequence entropy. The model explains the relative abundances of amino acids across a diverse set of proteomes. We found that the data are remarkably well explained when the cost function accounts for amino acid chemical decay. More than 100 organisms reach comparable solutions to the trade-off by different combinations of proteome cost and sequence diversity. Quantifying the interplay between proteome size and entropy shows that proteomes can get optimally large and diverse. PMID:25086000

Krick, Teresa; Verstraete, Nina; Alonso, Leonardo G.; Shub, David A.; Ferreiro, Diego U.; Shub, Michael; Sánchez, Ignacio E.

2014-01-01

139

Heterogeneous interaction between zwitterions of amino acids and glycerol in aqueous solutions at 298.15 K  

Microsoft Academic Search

The enthalpies of mixing of six kinds of amino acid (glycine, L-alanine, L-valine, L-serine, L-threonine, and L-proline) with\\u000a glycerol in aqueous solutions and the enthalpies of diluting of amino acid and glycerol aqueous solutions have been determined\\u000a by flow microcalorimetry at 298.15 K. Employing McMillan–Mayer theory, the enthalpies of mixing and diluting have been used\\u000a to calculate heterogeneous enthalpic pairwise interaction

Y. Li; Z. Yingyuan; L. Yonghui; J. Jing; W. Xiaoqing

2011-01-01

140

Amino Acid Degradation after Meteoritic Impact Simulation  

NASA Technical Reports Server (NTRS)

Amino acids are among the most important prebiotic molecules as it is from these precursors that the building blocks of life were formed [1]. Although organic molecules were among the components of the planetesimals making up the terrestrial planets, large amounts of primitive organic precursor molecules are believed to be exogenous in origin and to have been imported to the Earth via micrometeorites, carbonaceous meteorites and comets, especially during the early stages of the formation of the Solar System [1,2]. Our study concerns the hypothesis that prebiotic organic matter, present on Earth, was synthesized in the interstellar environment, and then imported to Earth by meteorites or micrometeorites. We are particularly concerned with the formation and fate of amino acids. We have already shown that amino acid synthesis is possible inside cometary grains under interstellar environment conditions [3]. We are now interested in the effects of space conditions and meteoritic impact on these amino acids [4-6]. Most of the extraterrestrial organic molecules known today have been identified in carbonaceous chondrite meteorites [7]. One of the components of these meteorites is a clay with a composition close to that of saponite, used in our experiments. Two American teams have studied the effects of impact on various amino acids [8,9]. [8] investigated amino acids in saturated solution in water with pressure ranges between 5.1 and 21 GPa and temperature ranges between 412 and 870 K. [9] studied amino acids in solid form associated with and without minerals (Murchison and Allende meteorite extracts) and pressure ranges between 3 and 30 GPa. In these two experiments, the amino acids survived up to 15 GPa. At higher pressure, the quantity of preserved amino acids decreases quickly. Some secondary products such as dipeptides and diketopiperazins were identified in the [8] experiment.

Bertrand, M.; Westall, F.; vanderGaast, S.; Vilas, F.; Hoerz, F.; Barnes, G.; Chabin, A.; Brack, A.

2008-01-01

141

Highly Efficient Asymmetric Synthesis of -Amino Acid Derivatives via  

E-print Network

Highly Efficient Asymmetric Synthesis of -Amino Acid Derivatives via Rhodium pure -amino acids and their deriva- tives are important building blocks for the synthesis of -peptides of -amino acids has attracted extensive interest. Although several stoichio- metric and catalytic methods

Zhang, Xumu

142

40 CFR 721.2584 - Dodecanoic acid, 12-amino-.  

...2014-07-01 false Dodecanoic acid, 12-amino-. 721.2584 Section 721...Substances § 721.2584 Dodecanoic acid, 12-amino-. (a) Chemical substance...substance identified as dodecanoic acid, 12-amino- (PMN P-98-0823;...

2014-07-01

143

40 CFR 721.2584 - Dodecanoic acid, 12-amino-.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Dodecanoic acid, 12-amino-. 721.2584 Section 721...Substances § 721.2584 Dodecanoic acid, 12-amino-. (a) Chemical substance...substance identified as dodecanoic acid, 12-amino- (PMN P-98-0823;...

2013-07-01

144

40 CFR 721.2584 - Dodecanoic acid, 12-amino-.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Dodecanoic acid, 12-amino-. 721.2584 Section 721...Substances § 721.2584 Dodecanoic acid, 12-amino-. (a) Chemical substance...substance identified as dodecanoic acid, 12-amino- (PMN P-98-0823;...

2012-07-01

145

Genetics Home Reference: Aromatic l-amino acid decarboxylase deficiency  

MedlinePLUS

... literature OMIM Genetic disorder catalog Conditions > Aromatic l-amino acid decarboxylase deficiency On this page: Description Genetic changes ... definitions Reviewed May 2008 What is aromatic l-amino acid decarboxylase deficiency? Aromatic l-amino acid decarboxylase (AADC) ...

146

40 CFR 721.2584 - Dodecanoic acid, 12-amino-.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Dodecanoic acid, 12-amino-. 721.2584 Section 721...Substances § 721.2584 Dodecanoic acid, 12-amino-. (a) Chemical substance...substance identified as dodecanoic acid, 12-amino- (PMN P-98-0823;...

2010-07-01

147

40 CFR 721.2584 - Dodecanoic acid, 12-amino-.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Dodecanoic acid, 12-amino-. 721.2584 Section 721...Substances § 721.2584 Dodecanoic acid, 12-amino-. (a) Chemical substance...substance identified as dodecanoic acid, 12-amino- (PMN P-98-0823;...

2011-07-01

148

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

149

Protein synthesis inhibition in neocortical grafts evaluated by systemic amino acid uptake autoradiography.  

PubMed

The temporal pattern of protein synthesis inhibition was examined in grafted neocortical neurons using [(3)H]valine in vivo autoradiography. Neuronal uptake levels of systemically administered (3)H-labeled amino acids which cross the blood-brain barrier (BBB) via endothelial cell neutral carriers have long been a hallmark in studies of experimental ischemic pathology; there is likely a strong correlation between persistent protein synthesis inhibition and the progression of cell damage. Because the grafting procedure involves the loss of blood flow and the subsequent reperfusion of the donor tissue there are, mechanistically, important similarities to reversible ischemia models. The effects of ischemic injury on grafted CNS neurons are not fully understood. Quantitative analysis of grain distribution in individual graft or control (adjacent host cortex) neurons indicated an initial breakdown of the amino acid barrier system, subsequent recovery, and progressive reduction of amino acid uptake by 1 year. Up to 3 weeks after surgery grafts were flooded with the [(3)H]valine tracer but individual neurons contained relatively few silver grains. After this time, the tracer was normally distributed within graft neurons but at significantly lower levels than in controls. Grain density gradually decreased over time such that 12-month grafted neurons had approximately half that compared to control and only 58% of that in 2-month grafts; the 12-month levels were comparable to those observed at early (10 days) postoperative times. Autoradiography of immunostained sections for MAP-2, SMI 311 (neurofilament marker), and neuron-specific enolase showed reduced expression of these proteins in neurons coupled with weak amino acid tracer uptake. The results further suggest that grafted neurons bear intriguing similarities to neurons placed at ischemic risk, particularly "penumbral" neurons, which are affected by reduced blood flow and are metabolically weakened. The loss of BBB properties in early grafts may also extend to the endothelial cell amino acid carrier system, and the delayed revascularization process could affect neuronal uptake mechanisms. PMID:10739633

Rosenstein, J M; Silverman, W F

2000-04-01

150

Differential effects of amino acid surface decoration on the anticancer efficacy of selenium nanoparticles.  

PubMed

The use of selenium for anticancer therapy has been heavily explored during the last decade. Amino acids (AAs) play central roles both as building blocks of proteins and intermediates in metabolism. In the present study, AAs-modified selenium nanoparticles (SeNPs@AAs) have been successfully synthesized in a simple redox system. Typical neutral (valine), acidic (aspartic acid) and basic (lysine) amino acids were used to decorate SeNPs, and the stable and homodisperse nanoparticles were characterized by zeta potential and transmission electron microscope. The result of X-ray photoelectron spectra (XPS) showed that the interaction of -NH3(+) groups of the amino acids with negative-charged SeNPs could be a driving force for dispersion of the nanoparticles. The screening of in vitro anticancer activities demonstrated that SeNPs@AAs exhibited differential growth inhibitory effects on various human cancer cell lines. Among them, SeNPs decorated by Lys displayed higher anticancer efficacy than those of valine and aspartic acid. The studies on the in vitro cellular uptake mechanisms revealed that SeNPs@AAs were internalized by cancer cells through endocytosis. Flow cytometric analysis and the determination of caspase activity indicated that treatment of the MCF-7 breast adenocarcinoma cells with SeNPs@AAs led to a dose-dependent increase in apoptosis. Moreover, it was found that SeNPs@AAs-induced ROS overproduction could be the upstream signal of caspase activation and mitochondrial dysfunction in cancer cells. Taken together, our results suggest that these amino acid biocompatible nanoparticles might have potential application as chemopreventive and chemotherapeutic agents for human cancers. PMID:24257441

Feng, Yanxian; Su, Jianyu; Zhao, Zhennan; Zheng, Wenjie; Wu, Hualian; Zhang, Yibo; Chen, Tianfeng

2014-01-28

151

Synthesis of N-carbobenzoxy-L-valyl-L-valyl-4-amino-3-hydroxy-5-methylhexanoic acid  

E-print Network

is extended to my wife, Corlis, for typing this thesis and her continued support during my graduate work. TABLE OF CONTENTS INTRODUCT1ON RESULTS AND DISCUSSION Synthesis of Ethyl 4-Amino-3-hydroxy-5- methylhexanoate Hydrochloride, Coupling Procedures...)-N-t-Butyloxycarbonyl-4-amino- 3-hydroxy-5-methylhexanoate (17a, 17b) Ethyl (38, 4S)-4-Amino-3-hydroxy-5-methylhexanoate Hydrochloride (18a). N-Carbobenzoxy-L-valine (19) Ethyl L-Valinate Hydrochloride (20). Ethyl N-Carbobenzoxy-L-valyl-L-valinate (21) N...

Hicks, Gary Dean

1980-01-01

152

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

2006-03-01

153

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

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Benzoic acid, 3-amino-, diazotized, coupled with...Substances § 721.1705 Benzoic acid, 3-amino-, diazotized, coupled with...generically identified as benzoic acid, 3-amino-, diazotized, coupled...

2013-07-01

154

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

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Benzoic acid, 3-amino-, diazotized, coupled with...Substances § 721.1705 Benzoic acid, 3-amino-, diazotized, coupled with...generically identified as benzoic acid, 3-amino-, diazotized, coupled...

2012-07-01

155

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

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Benzoic acid, 3-amino-, diazotized, coupled with...Substances § 721.1705 Benzoic acid, 3-amino-, diazotized, coupled with...generically identified as benzoic acid, 3-amino-, diazotized, coupled...

2011-07-01

156

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

...2014-07-01 false Benzoic acid, 3-amino-, diazotized, coupled with...Substances § 721.1705 Benzoic acid, 3-amino-, diazotized, coupled with...generically identified as benzoic acid, 3-amino-, diazotized, coupled...

2014-07-01

157

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 false Benzoic acid, 3-amino-, diazotized, coupled with...Substances § 721.1705 Benzoic acid, 3-amino-, diazotized, coupled with...generically identified as benzoic acid, 3-amino-, diazotized, coupled...

2010-07-01

158

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

159

Egg and whole-body amino acid profile of African bonytongue (Heterotis niloticus) with an estimation of their dietary indispensable amino acids requirements.  

PubMed

African bonytongue, Heterotis niloticus, is a river fish from the Central and West Africa basin. The species presents a great potential for fish farming and has been increasingly raised in Central and South Cameroon. The total amino acid and proximate composition of the whole body of egg, larva, juvenile, immature, and adult Heterotis were determined. Ash, moisture, whole-body protein, and lipid contents were significantly affected by size (P < 0.05). On the other hand, the amino acid composition of the whole-body tissue, when expressed as a percentage of dietary protein, was not significantly different among ontogenetic stages (ranging from 0.2 to 400 g mean body mass). The amino acid composition of the eggs was quite different to the one of whole-body tissue with lower levels of methionine, proline, and glycine, and higher levels of arginine, histidine, isoleucine, leucine, threonine, valine, serine, and alanine. The A/E ratios of adult Heterotis muscle tissue are similar to those obtained for other fish species, except for histidine and tryptophan. Based on whole-body or muscle tissue indispensable amino acids (IAA) to A/E ratios, the IAA requirement profiles for Heterotis (from larva to adult) were estimated and are similar to those of other omnivorous fish species, except for tryptophan and histidine. PMID:19544082

Monentcham, Serge-Eric; Whatelet, Bernard; Pouomogne, Victor; Kestemont, Patrick

2010-09-01

160

Amino acid sequence of squid troponin C  

Microsoft Academic Search

The complete amino acid sequence of squid Todarodes pacificus troponin C (TnC), which was shown to bind only 1 mol Ca2+\\/mol, was determined by both the Edman and cDNA methods. The squid TnC is composed of 147 amino acids including an unblocked Pro at the N-terminus and the calculated molecular weight is 17003.9. Among the four potential Ca2+-binding sites, namely

Takao Ojima; Tomokatsu Ohta; Kiyoyoshi Nishita

2001-01-01

161

Genetically encoded fluorescent coumarin amino acids  

DOEpatents

The invention relates to orthogonal pairs of tRNAs and aminoacyl-tRNA synthetases that can incorporate the coumarin unnatural amino acid L-(7-hydroxycoumarin-4-yl)ethylglycine into proteins produced in eubacterial host cells such as E. coli. The invention provides, for example but not limited to, novel orthogonal synthetases, methods for identifying and making the novel synthetases, methods for producing proteins containing the unnatural amino acid L-(7-hydroxycoumarin-4-yl)ethylglycine and related translation systems.

Wang, Jiangyun (San Diego, CA); Xie, Jianming (San Diego, CA); Schultz, Peter G. (La Jolla, CA)

2012-06-05

162

Genetically encoded fluorescent coumarin amino acids  

DOEpatents

The invention relates to orthogonal pairs of tRNAs and aminoacyl-tRNA synthetases that can incorporate the coumarin unnatural amino acid L-(7-hydroxycoumarin-4-yl) ethylglycine into proteins produced in eubacterial host cells such as E. coli. The invention provides, for example but not limited to, novel orthogonal synthetases, methods for identifying and making the novel synthetases, methods for producing proteins containing the unnatural amino acid L-(7-hydroxycoumarin-4-yl)ethylglycine and related translation systems.

Wang, Jiangyun (San Diego, CA); Xie, Jianming (San Diego, CA); Schultz, Peter G. (La Jolla, CA)

2010-10-05

163

Characterization and amino acid sequence of a fatty acid-binding protein from human heart.  

PubMed Central

The complete amino acid sequence of a fatty acid-binding protein from human heart was determined by automated Edman degradation of CNBr, BNPS-skatole [3'-bromo-3-methyl-2-(2-nitrobenzenesulphenyl)indolenine], hydroxylamine, Staphylococcus aureus V8 proteinase, tryptic and chymotryptic peptides, and by digestion of the protein with carboxypeptidase A. The sequence of the blocked N-terminal tryptic peptide from citraconylated protein was determined by collisionally induced decomposition mass spectrometry. The protein contains 132 amino acid residues, is enriched with respect to threonine and lysine, lacks cysteine, has an acetylated valine residue at the N-terminus, and has an Mr of 14768 and an isoelectric point of 5.25. This protein contains two short internal repeated sequences from residues 48-54 and from residues 114-119 located within regions of predicted beta-structure and decreasing hydrophobicity. These short repeats are contained within two longer repeated regions from residues 48-60 and residues 114-125, which display 62% sequence similarity. These regions could accommodate the charged and uncharged moieties of long-chain fatty acids and may represent fatty acid-binding domains consistent with the finding that human heart fatty acid-binding protein binds 2 mol of oleate or palmitate/mol of protein. Detailed evidence for the amino acid sequences of the peptides has been deposited as Supplementary Publication SUP 50143 (23 pages) at the British Library Lending Division, Boston Spa, Yorkshire LS23 7BQ, U.K., from whom copies may be obtained as indicated in Biochem. J. (1988) 249, 5. PMID:3421901

Offner, G D; Brecher, P; Sawlivich, W B; Costello, C E; Troxler, R F

1988-01-01

164

Polymers from amino acids: development of dual ester-urethane melt condensation approach and mechanistic aspects.  

PubMed

A new dual ester-urethane melt condensation methodology for biological monomers-amino acids was developed to synthesize new classes of thermoplastic polymers under eco-friendly and solvent-free polymerization approach. Naturally abundant L-amino acids were converted into dual functional ester-urethane monomers by tailor-made synthetic approach. Direct polycondensation of these amino acid monomers with commercial diols under melt condition produced high molecular weight poly(ester-urethane)s. The occurrence of the dual ester-urethane process and the structure of the new poly(ester-urethane)s were confirmed by (1)H and (13)C NMR. The new dual ester-urethane condensation approach was demonstrated for variety of amino acids: glycine, ?-alanine, L-alanine, L-leucine, L-valine, and L-phenylalanine. MALDI-TOF-MS end group analysis confirmed that the amino acid monomers were thermally stable under the melt polymerization condition. The mechanism of melt process and the kinetics of the polycondensation were studied by model reactions and it was found that the amino acid monomer was very special in the sense that their ester and urethane functionality could be selectively reacted by polymerization temperature or catalyst. The new polymers were self-organized as ?-sheet in aqueous or organic solvents and their thermal properties such as glass transition temperature and crystallinity could be readily varied using different l-amino acid monomers or diols in the feed. Thus, the current investigation opens up new platform of research activates for making thermally stable and renewable engineering thermoplastics from natural resource amino acids. PMID:22713137

Anantharaj, S; Jayakannan, M

2012-08-13

165

Ammonia and amino acid profiles in liver cirrhosis: Effects of variables leading to hepatic encephalopathy.  

PubMed

Hyperammonemia and severe amino acid imbalances play central role in hepatic encephalopathy (HE). In the article is demonstrated that the main source of ammonia in cirrhotic subjects is activated breakdown of glutamine (GLN) in enterocytes and the kidneys and the main source of GLN is ammonia detoxification to GLN in the brain and skeletal muscle. Branched-chain amino acids (BCAA; valine, leucine, and isoleucine) decrease due to activated GLN synthesis in muscle. Aromatic amino acids (AAA; phenylalanine, tyrosine, and tryptophan) and methionine increase due to portosystemic shunts and reduced ability of diseased liver. The effects on aminoacidemia of the following variables that may affect the course of liver disease are discussed: nutritional status, starvation, protein intake, inflammation, acute hepatocellular damage, bleeding from varices, portosystemic shunts, hepatic cancer, and renal failure. It is concluded that (1) neither ammonia nor amino acid concentrations correlate closely with the severity of liver disease; (2) BCAA/AAA ratio could be used as a good index of liver impairment and for early detection of derangements in amino acid metabolism; (3) variables potentially leading to overt encephalopathy exert substantial but uneven effects; and (4) careful monitoring of ammonia and aminoacidemia may discover important break points in the course of liver disease and indicate appropriate therapeutic approach. Of special importance might be isoleucine deficiency in bleeding from varices, arginine deficiency in sepsis, and a marked rise of GLN and ammonia levels that may appear in all events leading to HE. PMID:25220875

Holecek, Milan

2015-01-01

166

Amino acids in atmospheric droplets: perturbation of surface tension and critical supersaturation predicted by computer simulations  

NASA Astrophysics Data System (ADS)

Atmospheric amino acids constitute an important fraction of the water-soluble organic nitrogen compounds in both marine and continental aerosols, and have been confirmed as effective cloud condensation nuclei materials in laboratory tests. We here present a molecular dynamics study of amino acids representative for the remote marine atmospheric aerosol-cloud system, in order to investigate molecular distributions, orientations and induced changes in surface tension, and to evaluate their indirect effects on optical properties of clouds. These L-amino acids, including serine, glycine, alanine, valine, methionine and phenylalanine, are categorized as hydrophilic and hydrophobic according to their affinities to water. Different amino acids show distinct effects on the surface tension; even the same amino acid has different influence on the surface tension for planar and spherical interfaces. The curvature dependence of the surface tension is modelled by a quadratic polynomial function of the inverse of droplet radius, and such relationship is used to improve the Köhler equation in predicting the critical water vapour supersaturation of the droplet activation.

Li, X.; Hede, T.; Tu, Y.; Leck, C.; Ågren, H.

2011-11-01

167

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

2013-01-01

168

Amino acids in the Yamato carbonaceous chrondrite from Antarctica  

NASA Technical Reports Server (NTRS)

Evidence for the presence of amino acids of extraterrestrial origin in the Antarctic Yamato carbonaceous chrondrite is presented. Hydrolyzed and nonhydrolyzed water-extracted amino acid samples from exterior, middle and interior portions of the meteorite were analyzed by an amino acid analyzer and by gas chromatography of N-TFA-isopropyl amino acid derivatives. Nine protein and six nonprotein amino acids were detected in the meteorite at abundances between 34 and less than one nmole/g, with equal amounts in interior and exterior portions. Nearly equal abundances of the D and L enantiomers of alanine, aspartic acid and glutamic acid were found, indicating the abiotic, therefore extraterrestrial, origin of the amino acids. The Antarctic environment and the uniformity of protein amino acid abundances are discussed as evidence against the racemization of terrestrially acquired amino acids, and similarities between Yamato amino acid compositions and the amino acid compositions of the Murchison and Murray type II carbonaceous chrondrites are indicated.

Shimoyama, A.; Ponnamperuma, C.; Yanai, K.

1979-01-01

169

Transport of amino acids in the kidney.  

PubMed

Amino acids are the building blocks of proteins and key intermediates in the synthesis of biologically important molecules, as well as energy sources, neurotransmitters, regulators of cellular metabolism, etc. The efficient recovery of amino acids from the primary filtrate is a well-conserved key role of the kidney proximal tubule. Additionally, renal metabolism participates in the whole body disposition of amino acids. Therefore, a wide array of axially heterogeneously expressed transporters is localized on both epithelial membranes. For transepithelial transport, luminal uptake, which is carried out mainly by active symporters, is coupled with a mostly passive basolateral efflux. Many transporters require partner proteins for appropriate localization, or to modulate transporter activity, and/or increase substrate supply. Interacting proteins include cell surface antigens (CD98), endoplasmic reticulum proteins (GTRAP3-18 or 41), or enzymes (ACE2 and aminopeptidase N). In the past two decades, the molecular identification of transporters has led to significant advances in our understanding of amino acid transport and aminoacidurias arising from defects in renal transport. Furthermore, the three-dimensional crystal structures of bacterial homologues have been used to yield new insights on the structure and function of mammalian transporters. Additionally, transgenic animal models have contributed to our understanding of the role of amino acid transporters in the kidney and other organs and/or at critical developmental stages. Progress in elucidation of the renal contribution to systemic amino acid homeostasis requires further integration of kinetic, regulatory, and expression data of amino acid transporters into our understanding of physiological regulatory networks controlling metabolism. PMID:24692143

Makrides, Victoria; Camargo, Simone M R; Verrey, François

2014-01-01

170

The Branched-Chain Amino Acid Aminotransferase Encoded by ilvE Is Involved in Acid Tolerance in Streptococcus mutans  

PubMed Central

The ability of Streptococcus mutans to produce and tolerate organic acids from carbohydrate metabolism represents a major virulence factor responsible for the formation of carious lesions. Pyruvate is a key metabolic intermediate that, when rerouted to other metabolic pathways such as amino acid biosynthesis, results in the alleviation of acid stress by reducing acid end products and aiding in maintenance of intracellular pH. Amino acid biosynthetic genes such as ilvC and ilvE were identified as being upregulated in a proteome analysis of Streptococcus mutans under acid stress conditions (A. C. Len, D. W. Harty, and N. A. Jacques, Microbiology 150:1353–1366, 2004). In Lactococcus lactis and Staphylococcus carnosus, the ilvE gene product is involved with biosynthesis and degradation of branched-chain amino acids, as well as in the production of branched-chain fatty acids (B. Ganesan and B. C. Weimer, Appl. Environ. Microbiol. 70:638–641, 2004; S. M. Madsen et al., Appl. Environ. Microbiol. 68:4007–4014, 2002; and M. Yvon, S. Thirouin, L. Rijnen, D. Fromentier, and J. C. Gripon, Appl. Environ. Microbiol. 63:414–419, 1997). Here we constructed and characterized an ilvE deletion mutant of S. mutans UA159. Growth experiments revealed that the ilvE mutant strain has a lag in growth when nutritionally limited for branched-chain amino acids. We further demonstrated that the loss of ilvE causes a decrease in acid tolerance. The ilvE strain exhibits a defect in F1-Fo ATPase activity and has reduced catabolic activity for isoleucine and valine. Results from transcriptional studies showed that the ilvE promoter is upregulated during growth at low pH. Collectively, the results of this investigation show that amino acid metabolism is a component of the acid-adaptive repertoire of S. mutans. PMID:22328677

Santiago, Brendaliz; MacGilvray, Matthew; Faustoferri, Roberta C.

2012-01-01

171

Amino Acid Odorants Stimulate Microvillar Sensory Neurons  

Microsoft Academic Search

The olfactory epithelium (OE) of zebrafish is populated with ciliated and microvillar olfactory sensory neurons (OSNs). Whether distinct classes of odorants specifically activate either of these unique populations of OSNs is unknown. Previously we demonstrated that zebrafish OSNs could be labeled in an activity-dependent fashion by amino acid but not bile acid odorants. To determine which sensory neuron type was

David L. Lipschitz; William C. Michel

2002-01-01

172

What Amino Acid Properties Affect Protein Evolution? Xuhua Xia,1  

E-print Network

What Amino Acid Properties Affect Protein Evolution? Xuhua Xia,1 Wen-Hsiung Li2 1 Department the effects of 10 amino acid properties on the evolution of the genetic code, the amino acid composition of proteins, and the pattern of nonsynonymous substitutions. The 10 amino acid properties studied

Xia, Xuhua

173

Original article Rumen effective degradability of amino acids  

E-print Network

Original article Rumen effective degradability of amino acids from soybean meal corrected degradation kinetics and effective degradability of individual amino acids, total analysed amino acids (TAA was similar for TAA and CP (74.7 vs. 75.7%). Degradability values of individual amino acids varied moderately

Paris-Sud XI, Université de

174

Free amino acids in brain, liver, and skeletal muscle tissue of voles infected with Trypanosoma brucei gambiense.  

PubMed

The concentrations of several acidic and neutral amino acids of brain, liver, and skeletal muscle were determined in field voles, Microtus montanus, and compared to values obtained from voles harboring a chronic infection of Trypanosoma brucei gambiense. All of the amino acids examined were found at comparable levels in brain tissue from both groups of animals with the exception of tyrosine, which was reduced by approximately 45% in the infected voles. Similarly, the only difference noted in liver tissue was 32% decrease of free tyrosine in the infected animals. With respect to muscle tissue, in addition to a 45% reduction of free tyrosine in the infected voles, decreases of a smaller magnitude were also noted for threonine, glutamate, and valine. The relatively specific alteration of free tyrosine concentrations in the investigated tissues of trypanosome-infected animals suggests an alteration in host metabolism of this amino acid and/or parasite utilization. PMID:338875

Newport, G R; Page, C R

1977-12-01

175

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. PMID:16667654

Walters, Donald S.; Steffens, John C.

1990-01-01

176

Phenylalanine sensitive K562-D cells for the analysis of the biochemical impact of excess amino acid.  

PubMed

Although it is recognized that the abnormal accumulation of amino acid is a cause of the symptoms in metabolic disease such as phenylketonuria (PKU), the relationship between disease severity and serum amino acid levels is not well understood due to the lack of experimental model. Here, we present a novel in vitro cellular model using K562-D cells that proliferate slowly in the presence of excessive amount of phenylalanine within the clinically observed range, but not phenylpyruvate. The increased expression of the L-type amino acid transporter (LAT2) and its adapter protein 4F2 heavy chain appeared to be responsible for the higher sensitivity to phenylalanine in K562-D cells. Supplementation with valine over phenylalanine effectively restored cell proliferation, although other amino acids did not improve K562-D cell proliferation over phenylalanine. Biochemical analysis revealed mammalian target of rapamycin complex (mTORC) as a terminal target of phenylalanine in K562-D cell proliferation, and supplementation of valine restored mTORC1 activity. Our results show that K562-D cell can be a potent tool for the investigation of PKU at the molecular level and to explore new therapeutic approaches to the disease. PMID:25373594

Sanayama, Yoshitami; Matsumoto, Akio; Shimojo, Naoki; Kohno, Yoichi; Nakaya, Haruaki

2014-01-01

177

Phenylalanine sensitive K562-D cells for the analysis of the biochemical impact of excess amino acid  

PubMed Central

Although it is recognized that the abnormal accumulation of amino acid is a cause of the symptoms in metabolic disease such as phenylketonuria (PKU), the relationship between disease severity and serum amino acid levels is not well understood due to the lack of experimental model. Here, we present a novel in vitro cellular model using K562-D cells that proliferate slowly in the presence of excessive amount of phenylalanine within the clinically observed range, but not phenylpyruvate. The increased expression of the L-type amino acid transporter (LAT2) and its adapter protein 4F2 heavy chain appeared to be responsible for the higher sensitivity to phenylalanine in K562-D cells. Supplementation with valine over phenylalanine effectively restored cell proliferation, although other amino acids did not improve K562-D cell proliferation over phenylalanine. Biochemical analysis revealed mammalian target of rapamycin complex (mTORC) as a terminal target of phenylalanine in K562-D cell proliferation, and supplementation of valine restored mTORC1 activity. Our results show that K562-D cell can be a potent tool for the investigation of PKU at the molecular level and to explore new therapeutic approaches to the disease. PMID:25373594

Sanayama, Yoshitami; Matsumoto, Akio; Shimojo, Naoki; Kohno, Yoichi; Nakaya, Haruaki

2014-01-01

178

Distinguishing Proteins From Arbitrary Amino Acid Sequences  

PubMed Central

What kinds of amino acid sequences could possibly be protein sequences? From all existing databases that we can find, known proteins are only a small fraction of all possible combinations of amino acids. Beginning with Sanger's first detailed determination of a protein sequence in 1952, previous studies have focused on describing the structure of existing protein sequences in order to construct the protein universe. No one, however, has developed a criteria for determining whether an arbitrary amino acid sequence can be a protein. Here we show that when the collection of arbitrary amino acid sequences is viewed in an appropriate geometric context, the protein sequences cluster together. This leads to a new computational test, described here, that has proved to be remarkably accurate at determining whether an arbitrary amino acid sequence can be a protein. Even more, if the results of this test indicate that the sequence can be a protein, and it is indeed a protein sequence, then its identity as a protein sequence is uniquely defined. We anticipate our computational test will be useful for those who are attempting to complete the job of discovering all proteins, or constructing the protein universe. PMID:25609314

Yau, Stephen S.-T.; Mao, Wei-Guang; Benson, Max; He, Rong Lucy

2015-01-01

179

Distinguishing proteins from arbitrary amino Acid sequences.  

PubMed

What kinds of amino acid sequences could possibly be protein sequences? From all existing databases that we can find, known proteins are only a small fraction of all possible combinations of amino acids. Beginning with Sanger's first detailed determination of a protein sequence in 1952, previous studies have focused on describing the structure of existing protein sequences in order to construct the protein universe. No one, however, has developed a criteria for determining whether an arbitrary amino acid sequence can be a protein. Here we show that when the collection of arbitrary amino acid sequences is viewed in an appropriate geometric context, the protein sequences cluster together. This leads to a new computational test, described here, that has proved to be remarkably accurate at determining whether an arbitrary amino acid sequence can be a protein. Even more, if the results of this test indicate that the sequence can be a protein, and it is indeed a protein sequence, then its identity as a protein sequence is uniquely defined. We anticipate our computational test will be useful for those who are attempting to complete the job of discovering all proteins, or constructing the protein universe. PMID:25609314

Yau, Stephen S-T; Mao, Wei-Guang; Benson, Max; He, Rong Lucy

2015-01-01

180

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

181

Amino acid uptake in rust fungi  

PubMed Central

The plant pathogenic rust fungi colonize leaf tissue and feed off their host plants without killing them. Certain economically important species of different genera such as Melampsora, Phakopsora, Puccinia, or Uromyces are extensively studied for resolving the mechanisms of the obligate biotrophy. As obligate parasites rust fungi only can complete their life cycle on living hosts where they grow through the leaf tissue by developing an extended network of intercellular hyphae from which intracellular haustoria are differentiated. Haustoria are involved in key functions of the obligate biotrophic lifestyle: suppressing host defense responses and acquiring nutrients. This review provides a survey of rust fungi nitrogen nutrition with special emphasis on amino acid uptake. A variety of sequences of amino acid transporter genes of rust fungi have been published; however, transport activity of only three in planta highly up-regulated amino acid permeases have been characterized. Functional and immunohistochemical investigations have shown the specificity and localization of these transporters. Sequence data of various genome projects allowed identification of numerous rust amino acid transporter genes. An in silico analysis reveals that these genes can be classified into different transporter families. In addition, genetic and molecular data of amino acid transporters have provided new insights in the corresponding metabolic pathways.

Struck, Christine

2015-01-01

182

L-amino acid oxidases with specificity for basic L-amino acids in cyanobacteria.  

PubMed

The two closely related fresh water cyanobacteria Synechococcus elongatus PCC 6301 and Synechococcus elongatus PCC 7942 have previously been shown to constitutively express a FAD-containing L-amino acid oxidase with high specificity for basic L-amino acids (L-arginine being the best substrate). In this paper we show that such an enzyme is also present in the fresh water cyanobacterium Synechococcus cedrorum PCC 6908. In addition, an improved evaluation of the nucleotide/amino acid sequence of the L-amino acid oxidase of Synechococcus elongatus PCC 6301 (encoded by the aoxA gene) with respect to the FAD-binding site and a translocation pathway signal sequence will be given. Moreover, the genome sequences of 24 cyanobacteria will be evaluated for the occurrence of an aoxA-similar gene. In the evaluated cyanobacteria 15 genes encoding an L-amino acid oxidase-similar protein will be found. PMID:17542496

Gau, Achim E; Heindl, Achim; Nodop, Anke; Kahmann, Uwe; Pistorius, Elfriede K

2007-01-01

183

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

184

Amino acid sequence in constitutionally isomeric tetrapeptide amphiphiles dictates architecture of one-dimensional nanostructures.  

PubMed

The switching of two adjacent amino acids can lead to differences in how proteins fold thus affecting their function. This effect has not been extensively explored in synthetic peptides in the context of supramolecular self-assembly. Toward this end, we report here the use of isomeric peptide amphiphiles as molecular building blocks to create one-dimensional (1D) nanostructures. We show that four peptide amphiphile isomers, with identical composition but a different sequence of their four amino acids, can form drastically different types of 1D nanostructures under the same conditions. We found that molecules with a peptide sequence of alternating hydrophobic and hydrophilic amino acids such as VEVE and EVEV self-assemble into flat nanostructures that can be either helical or twisted. On the other hand, nonalternating isomers such as VVEE and EEVV result in the formation of cylindrical nanofibers. Furthermore, we also found that when the glutamic acid is adjacent to the alkyl tail the supramolecular assemblies appear to be internally flexible compared to those with valine as the first amino acid. These results clearly demonstrate the significance of peptide side chain interactions in determining the architectures of supramolecular assemblies. PMID:25144245

Cui, Honggang; Cheetham, Andrew G; Pashuck, E Thomas; Stupp, Samuel I

2014-09-01

185

Cometary Amino Acids from the STARDUST Mission  

NASA Technical Reports Server (NTRS)

NASA's Stardust spacecraft returned samples from comet 81 P/WiId 2 to Earth in January 2006. Examinations of the organic compounds in cometary samples can reveal information about the prebiotic organic inventory present on the early Earth and within the early Solar System, which may have contributed to the origin of life. Preliminary studies of Stardust material revealed the presence of a suite of organic compounds including several amines and amino acids, but the origin of these compounds (cometary vs. terrestrial contamination) could not be identified. We have recently measured the carbon isotopic ratios of these amino acids to determine their origin, leading to the first detection of a cometary amino acid.

Cook, Jamie Elsila

2009-01-01

186

Terahertz broadband spectroscopic investigations of amino acid  

NASA Astrophysics Data System (ADS)

We present an experimental terahertz (THz) spectroscopic investigation of amino acid using an air-breakdown-coherent detection (ABCD) system. The strong and ultra-broadband (0.1 to 10THz) terahertz radiations generated by two-color laser induced air plasma and measured by coherent heterodyne detection. The broadband THz reflection spectra of L-Lysine (C6H14N2O2) and L-Arginine (C6H14N2O2) are obtained. To solve the phase-retrieval problem in RTDS, the absorption signatures of the materials are extracted directly from the first derivative of the relative reflectance with respect to frequency. The absorption features of the two amino acids are characterized in the 0.5~6 THz region. It is found that both the two amino acids have an absorption peak at 1.10 THz.

Zhu, De-chong; Zhang, Liang-liang; Zhong, Hua; Zhang, Cun-lin

2011-08-01

187

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)

2005-04-01

188

New Glycoprotein-Associated Amino Acid Transporters  

Microsoft Academic Search

.   The L-type amino acid transporter LAT1 has recently been identified as being a disulfide-linked ``light chain'' of the ubiquitously\\u000a expressed glycoprotein 4F2hc\\/CD98. Several LAT1-related transporters have been identified, which share the same putative 12-transmembrane\\u000a segment topology and also associate with the single transmembrane domain 4F2hc protein. They display differing amino acid\\u000a substrate specificities, transport kinetics and localizations such as,

F. Verrey; D. L. Jack; I. T. Paulsen; R. Pfeiffer

1999-01-01

189

Expression and adaptive regulation of amino acid transport system A in a placental cell line under amino acid restriction  

Microsoft Academic Search

Trans-placental transport of amino acids is vital for the developing fetus. Using the BeWo cell line as a placental model, we investigated the effect of restricting amino acid availability on amino acid transport system type A. BeWo cells were cultured either in amino acid-depleted (without non-essential amino acids) or control media for 1, 3, 5 or 6h. System A function

H N Jones; C J Ashworth; H J McArdle; Aberdeen AB

2006-01-01

190

Original article Ileal true digestibility of amino acids  

E-print Network

Original article Ileal true digestibility of amino acids in wheat milling by-products for pigs (WF), 3 of wheat bran (WB) ­ were analysed and studied for their protein and amino acid ileal true the least digestible amino acids, whereas methionine was among the most digestible ones. N and all amino

Paris-Sud XI, Université de

191

An amino acid transporter involved in gastric acid secretion  

Microsoft Academic Search

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

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

2006-01-01

192

Anthelmintic efficacy of genistein, the active principle of Flemingia vestita (Fabaceae): alterations in the free amino acid pool and ammonia levels in the fluke, Fasciolopsis buski.  

PubMed

The crude root-peel extract of Flemingia vestita, its active principle genistein and the reference flukicide oxyclozanide were tested against Fasciolopsis buski, the giant intestinal trematode. The amino acid composition of F. buski was demonstrated using HPLC and it was observed that the free amino acid (FAA) pool of the control worm consisted of aspartate, threonine, serine, glutamic acid, glutamine, proline, glycine, alanine, valine, methionine, isoleucine, leucine, tyrosine, lysine, histidine, arginine, phosphoserine, taurine, citrulline, ornithine, beta-alanine, and gamma-amino butyric acid (GABA). Of the amino acids detected valine was found to be the maximum in quantitative analysis. In qualitative analysis the FAA pool of the parasites under various treatments remained same as that of the control; however, quantitatively the level of various FAAs in the parasite was significantly affected. The treated parasites showed a marked decrease in the levels of arginine, ornithine, tyrosine, leucine, isoleucine, valine, alanine, glycine, proline, serine, threonine, and taurine following treatment with 20 mg/ml of crude peel extract, 0.5 mg/ml of genistein and 20 mg/ml of the reference drug, though an increase in the levels of glutamic acid, glutamine, phosphoserine, citrulline and GABA was noticeable. Enhanced levels of GABA and citrulline under the influence of genistein may be implicated in alterations of nitric oxide release and consequent neurological change (e.g. paralysis) in the parasite. Ammonia in the tissue homogenate as well as in the incubation medium showed a quantitative increase compared to the controls after treatment with the various test materials. The ammonia level increased by 40.7%, 66.4% and 18.16% in treatments with F. vestita, genistein and oxyclozanide, respectively, at the mentioned dosages. The changes in the levels of the amino acids and nitrogen components post treatment suggest that the amino acid metabolism in the parasite may have been altered under the influence of the test materials. PMID:15464437

Kar, Pradip Kumar; Tandon, Veena; Saha, Nirmalendu

2004-12-01

193

Compartmentalization of amino acids in surfactant aggregates - Partitioning between water and aqueous micellar sodium dodecanoate and between hexane and dodecylammonium propionate trapped water in hexane  

NASA Technical Reports Server (NTRS)

The partitioning of amino acids (glycine, alanine, leucine, phenylalanine, histidine, aspartic acid, glutamic acid, lysine, isoleucine, threonine, serine, valine, proline, arginine) in aqueous and nonaqueous micellar systems was studied experimentally. Partitioning from neat hexane into dodecylammonium propionate trapped water in hexane was found to be dependent on both electrostatic and hydrophobic interactions, which implies that the interior of dodecylammonium propionate aggregates is negatively charged and is capable of hydrogen bonding in addition to providing a hydrophobic environment. Unitary free energies of transfer of amino acid side chains from hexane to water were determined and solubilities of amino acids in neat hexane substantiated the amino acid hydrophobicity scale. The relevance of the experiments to prebiotic chemistry was examined.

Fendler, J. H.; Nome, F.; Nagyvary, J.

1975-01-01

194

Enhanced production of branched-chain amino acids by Gluconacetobacter europaeus with a specific regional deletion in a leucine responsive regulator.  

PubMed

Vinegar with increased amounts of branched-chain amino acids (BCAAs; valine, leucine and isoleucine) is favorable for human health as BCAAs decrease diet-induced obesity and hyperglycemia. To construct Gluconacetobacter europaeus which produces BCAAs, leucine responsive regulator (GeLrp) is focused and two Gelrp mutants were constructed. Wild-type KGMA0119 didn't produce significant amount of valine (0.13 mM) and leucine (0 mM) and strain KGMA7110 which lacks complete Gelrp accumulated valine (0.48 mM) and leucine (0.11 mM) but showed impaired growth, and it was fully restored in the presence of essential amino acids. Strain KGMA7203 was then constructed with a nonsense mutation at codon Trp132 in the Gelrp, which leads a specific deletion at an estimated ligand-sensing region in the C-terminal domain. KGMA7203 produced greater quantities of valine (0.80 mM) and leucine (0.26 mM) and showed the same growth characteristics as KGMA0119. mRNA levels of BCAAs biosynthesis genes (ilvI and ilvC) and probable BCAAs efflux pump (leuE) were determined by quantitative reverse-transcription PCR. Expression rates of ilvI and ilvC in the two Gelrp disruptants were greater than those in KGMA0119. leuE was highly expressed in KGMA7110 only, suggesting that the accumulation in KGMA7110 culture was caused by increased expression of the biosynthesis genes and abnormal enhanced export of amino acids resulting in impaired cell growth. In contrast, KGMA7203 would achieve the high level production through enhanced expression of the biosynthesis genes without enhancing that for the efflux pump. KGMA7203 was considered advantageous for production of vinegar with higher amounts of valine and leucine. PMID:24985571

Akasaka, Naoki; Ishii, Yuri; Hidese, Ryota; Sakoda, Hisao; Fujiwara, Shinsuke

2014-12-01

195

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

196

Intestinal metabolism of sulfur amino acids  

Technology Transfer Automated Retrieval System (TEKTRAN)

The gastrointestinal tract (GIT) is a metabolically significant site of sulfur amino acid (SAA) metabolism in the body and metabolizes approx. 20% of the dietary methionine intake that is mainly transmethylated to homocysteine and transsulfurated to cysteine. The GIT accounts for approx. 25% of the ...

197

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

198

Amino acid profile in Down's syndrome.  

PubMed Central

Fasting plasma and urinary amino acid concentrations were studied under carefully controlled conditions in 22 children with Down's syndrome and in age matched controls. The only significant difference between the groups was a higher mean plasma lysine concentration in Down's syndrome patients compared to controls. PMID:8669939

Heggarty, H J; Ball, R; Smith, M; Henderson, M J

1996-01-01

199

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. PMID:16659967

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

1977-01-01

200

Branched-chain amino acids alleviate nonalcoholic steatohepatitis in rats.  

PubMed

Nonalcoholic steatohepatitis (NASH) is a prevalent disease in countries around the world. The branched-chain amino acids (BCAAs) leucine, isoleucine, and valine cannot be synthesized by the body and have been shown to promote muscle buildup; thus, it is logical to suggest that BCAAs can reduce fat deposition in the body. We used gonadectomized rats fed a high-fat diet to investigate the effects of BCAAs on lipid metabolism over an 8-week experimental period. Body composition, tissue histology, plasma lipid indices, and hormone levels were examined. We demonstrated that the body weights of rats were not significantly decreased but the mesenteric fat was significantly decreased (p < 0.05) in BCAA-treated rats. In addition, BCAAs decreased plasma lipid levels and fat deposition in the liver. At week 4, when the untreated rats displayed macrovesicular steatosis, BCAA-treated rats had only macrovesicular droplets in their hepatocytes. At week 8, when the untreated rat livers displayed profound inflammation and cirrhosis, BCAA-treated rat livers remained in the macrovesicular stage of steatosis. BCAAs induced higher blood glucose and plasma insulin levels (p < 0.05). BCAAs also improved liver blood flow by increasing mean arterial blood pressure and decreasing portal pressure, which helped delay the change in blood flow pattern to that of cirrhosis. BCAAs also induced the skeletal muscle to express higher levels of branched-chain ?-keto acid dehydrogenase E1?, which indicates an enhanced metabolic capacity of BCAAs in muscle tissue. This study clearly demonstrates the effects of BCAAs on the amelioration of fat deposition in rats fed a high-fat diet. PMID:23855271

Li, Tianrun; Geng, Leiluo; Chen, Xin; Miskowiec, Miranda; Li, Xuan; Dong, Bing

2013-08-01

201

Brain–blood amino acid correlates following protein restriction in murine maple syrup urine disease  

PubMed Central

Background Conventional therapy for patients with maple syrup urine disease (MSUD) entails restriction of protein intake to maintain acceptable levels of the branched chain amino acid, leucine (LEU), monitored in blood. However, no data exists on the correlation between brain and blood LEU with protein restriction, and whether correction in blood is reflected in brain. Methods To address this question, we fed intermediate MSUD mice diets of 19% (standard) and 6% protein, with collection of sera (SE), striata (STR), cerebellum (CE) and cortex (CTX) for quantitative amino acid analyses. Results LEU and valine (VAL) levels in all brain regions improved on average 28% when shifting from 19% to 6% protein, whereas the same improvements in SE were on average 60%. Isoleucine (ILE) in brain regions did not improve, while the SE level improved 24% with low-protein consumption. Blood-branched chain amino acids (LEU, ILE, and VAL in sera (SE)) were 362-434 ?M, consistent with human values considered within control. Nonetheless, numerous amino acids in brain regions remained abnormal despite protein restriction, including glutamine (GLN), aspartate (ASP), glutamate (GLU), gamma-aminobutyric acid (GABA), asparagine (ASN), citrulline (CIT) and serine (SER). To assess the specificity of these anomalies, we piloted preliminary studies in hyperphenylalaninemic mice, modeling another large neutral aminoacidopathy. Employing an identical dietary regimen, we found remarkably consistent abnormalities in GLN, ASP, and GLU. Conclusions Our results suggest that blood amino acid analysis may be a poor surrogate for assessing the outcomes of protein restriction in the large neutral amino acidopathies, and further indicate that chronic neurotransmitter disruptions (GLU, GABA, ASP) may contribute to long-term neurocognitive dysfunction in these disorders. PMID:24886632

2014-01-01

202

FREE AMINO ACID CONTENT OF EWE UTERINE FLUID  

E-print Network

FREE AMINO ACID CONTENT OF EWE UTERINE FLUID UNDER VARIOUS HORMONAL TREATMENTS DURING EARLY Recherches zootechniques, I. N. R. A., i'8350 Jouy en Josas SUMMARY Free amino acids are dosed in ewe uterine secretions are very rich in free amino acids, especially glutamic acid + glutamine and glycine. However

Paris-Sud XI, Université de

203

Molecular Structure of Valine  

NSDL National Science Digital Library

Valine was isolated in 1901 by the chemist Emil Fischer from casein and is acquired by hydrolyzing proteins. It is mostly found in muscles and is required for muscle metabolism, repair and growth of tissue, and maintaining nitrogen balance in the body. It can also be used in substrate recognition. However, its key role is in the muscle where it is used as an energy source. Valine reverses and treats hepatic encephalopathy, alcohol related brain damages, and degenerative neurological conditions. Research has indicated that valine aids in restoring muscle mass in people who have liver disease, any injuries, or who have had surgery. Good sources of valine are dairy, meat, grain, mushrooms, soy and peanuts.

2002-08-22

204

Nonconventional techniques for separation of biosynthetic amino acids.  

PubMed

Amino acids can be obtained by biosynthesis, by protein hydrolysis or by extraction from natural sources. The most efficient methods are the first two, but the separation of amino acids from fermentation broths or protein hydrolysates is rather difficult. Amino acids dissociate in aqueous solutions, forming characteristic ionic species depending on the solution pH-value. These properties make amino acids to be hydrophilic at any pH-value. This paper presents a review of the separation studies of some amino acids by nonconventional methods, namely individual or selective reactive extraction. Separation of some amino acids from their mixture obtained either by fermentation or protein hydrolysis by reactive extraction with different extractants indicated the possibility of the amino acids selective separation as a function of the pH-value of aqueous solution correlated with the acidic or basic character of each amino acid. PMID:24741809

Kloetzer, Lenu?a; Po?taru, M?d?lina; Cheptea, Corina; Ca?caval, D; Galaction, Anca-Irina

2014-01-01

205

Amino acid regulation of TOR complex 1.  

PubMed

TOR complex 1 (TORC1), an oligomer of the mTOR (mammalian target of rapamycin) protein kinase, its substrate binding subunit raptor, and the polypeptide Lst8/GbetaL, 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. PMID:18765678

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

2009-04-01

206

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. PMID:18765678

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

2009-01-01

207

Enantioseparation of N-derivatized amino acids by micro-liquid chromatography using carbamoylated quinidine functionalized monolithic stationary phase.  

PubMed

In order to obtain satisfactory column permeability, efficiency and selectivity for micro-HPLC, a capillary monolithic column containing O-9-[2-(methacryloyloxy)-ethylcarbamoyl]-10,11-dihydroquinidine (MQD) as chiral selector was re-optimized. The monolithic column was used to successfully enantioresolve a wide range of N-derivatized amino acids including alanine, leucine, methionine, threonine, phenylalanine, valine, serine, isoleucine, tryptophan, and cysteine. The influence of mobile phase parameters, such as the organic solvent type and concentration, the apparent pH, and buffer concentration, on retention and enantioseparation of N-derivatized amino acids has been investigated. 3,5-dinitrobenzoyl-amino acids and 3,5-dichlorobenzoyl-amino acids were resolved into enantiomers with exceptionally high selectivity and resolution. The chemoselectivity of the monolithic column for a multicomponent mixture of N-derivatized amino acids was also investigated. A mixture of three pairs of 3,5-dichlorobenzoyl-amino acids could be fully resolved in 22.5 min. PMID:24999069

Wang, Qiqin; Feng, Jun; Han, Hai; Zhu, Peijie; Wu, Huihui; Marina, Maria Luisa; Crommen, Jacques; Jiang, Zhengjin

2014-10-10

208

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

NASA Technical Reports Server (NTRS)

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 minor effects on the permeability coefficients of the amino acids tested in liposomes. Increasing the membrane surface charge increased the permeability of amino acids of the opposite charge, while increasing the cholesterol content decreased membrane permeability. The permeability coefficients for most amino acids tested were surprisingly similar to those previously measured for monovalent cations such as sodium and potassium (approximately 10(-12)-10(-13) cm s-1). This observation suggests that the permeation rates for the neutral, polar and charged amino acids are controlled by bilayer fluctuations and transient defects, rather than partition coefficients and Born energy barriers. Hydrophobic amino acids were 10(2) more permeable than the hydrophilic forms, reflecting their increased partition coefficient values. External pH had dramatic effects on the permeation rates for the modified amino acid lysine methyl ester in response to transmembrane pH gradients. It was established that lysine methyl ester and other modified short peptides permeate rapidly (P = 10(-2) cm s-1) as neutral (deprotonated) molecules. It was also shown that charge distributions dramatically alter permeation rates for modified di-peptides. These results may relate to the movement of peptides through membranes during protein translocation and to the origin of cellular membrane transport on the early Earth.

Chakrabarti, A. C.; Deamer, D. W. (Principal Investigator); Miller, S. L. (Principal Investigator)

1994-01-01

209

The development and amino acid binding ability of nano-materials based on azo derivatives: theory and experiment.  

PubMed

Two nano-material-containing azo groups have been designed and developed, and the binding ability of nano-materials with various amino acids has been characterized by UV-vis and fluorescence titrations. Results indicated that two nano-materials showed the strongest binding ability for homocysteine among twenty normal kinds of amino acids (alanine, valine, leucine, isoleucine, methionine, aspartic acid, glutamic acid, arginine, glycine, serine, threonine, asparagine, phenylalanine, histidine, tryptophan, proline, lysine, glutamine, tyrosine and homocysteine). The reason for the high sensitivity for homocysteine was that two nano-materials containing an aldehyde group reacted with SH in homocysteine and afforded very stable thiazolidine derivatives. Theoretical investigation further illustrated the possible binding mode in host-guest interaction and the roles of molecular frontier orbitals in molecular interplay. Thus, the two nano-materials can be used as optical sensors for the detection of homocysteine. PMID:24656358

Shang, Xuefang; Du, Jinge; Yang, Wancai; Liu, Yun; Fu, Zhiyuan; Wei, Xiaofang; Yan, Ruifang; Yao, Ningcong; Guo, Yaping; Zhang, Jinlian; Xu, Xiufang

2014-05-01

210

Alterations of Amino Acid Level in Depressed Rat Brain  

PubMed Central

Amino-acid neurotransmitter system dysfunction plays a major role in the pathophysiology of depression. Several studies have demonstrated the potential of amino acids as a source of neuro-specific biomarkers could be used in future diagnosis of depression. Only partial amino acids such as glycine and asparagine were determined from certain parts of rats' brain included hippocampi and cerebral cortex in previous studies. However, according to systematic biology, amino acids in different area of brain are interacted and interrelated. Hence, the determination of 34 amino acids through entire rats' brain was conducted in this study in order to demonstrate more possibilities for biomarkers of depression by discovering other potential amino acids in more areas of rats' brain. As a result, 4 amino acids (L-aspartic acid, L-glutamine, taurine and ?-amino-n-butyric acid) among 34 were typically identified as potentially primary biomarkers of depression by data statistics. Meanwhile, an antidepressant called Fluoxetine was employed to verify other potential amino acids which were not identified by data statistics. Eventually, we found L-?-amino-adipic acid could also become a new potentially secondary biomarker of depression after drug validation. In conclusion, we suggested that L-aspartic acid, L-glutamine, taurine, ?-amino-n-butyric acid and L-?-amino-adipic acid might become potential biomarkers for future diagnosis of depression and development of antidepressant. PMID:25352755

Yang, Pei; Li, Xuechun; Tian, Jingchen; Jing, Fu; Qu, Changhai; Lin, Longfei; Zhang, Hui

2014-01-01

211

Fatty acid-amino acid conjugates diversification in Lepidopteran caterpillars  

Technology Transfer Automated Retrieval System (TEKTRAN)

Fatty acid amino acid conjugates (FACs) have been found in Noctuid as well as Sphingid caterpillar oral secretions and especially volicitin [N-(17-hydroxylinolenoyl)-L-Glutamine] and its biochemical precursor, N-linolenoyl-L-glutamine, are known elicitors of induced volatile emissions in corn plants...

212

Allied Health Chemistry Laboratory: Amino Acids, Insulin, Proteins, and Skin  

ERIC Educational Resources Information Center

Presents a laboratory experiment specifically designed for allied health students. The students construct molecular models of amino acids, extract amino acids from their skin with hot water, and chromatographically analyze the skin extract and hydrolyzed insulin. (MLH)

Dever, David F.

1975-01-01

213

Single amino acid supplementation in aminoacidopathies: a systematic review  

PubMed Central

Aminoacidopathies are a group of rare and diverse disorders, caused by the deficiency of an enzyme or transporter involved in amino acid metabolism. For most aminoacidopathies, dietary management is the mainstay of treatment. Such treatment includes severe natural protein restriction, combined with protein substitution with all amino acids except the amino acids prior to the metabolic block and enriched with the amino acid that has become essential by the enzymatic defect. For some aminoacidopathies, supplementation of one or two amino acids, that have not become essential by the enzymatic defect, has been suggested. This so-called single amino acid supplementation can serve different treatment objectives, but evidence is limited. The aim of the present article is to provide a systematic review on the reasons for applications of single amino acid supplementation in aminoacidopathies treated with natural protein restriction and synthetic amino acid mixtures. PMID:24422943

2014-01-01

214

Valproate disturbs the balance between branched and aromatic amino acids in rats.  

PubMed

We investigated the effect of valproate (ip, 500 mg/kg), which is regarded as a potent plasma protein tryptophan (TRP) displacer, on the central nervous system (hippocampal) and peripheral (plasma) levels of the aromatic amino acids (AAAs; e.g. TRP, tyrosine and phenylalanine) and branched-chain amino acids (BCAAs; e.g. valine, isoleucine and leucine) as well as the other amino acids (glutamate, GABA, alanine, glutamine, glycine, aspartate and taurine) involved in the regulation of neurotransmission. Furthermore, we investigated whether the changes in the BCAA/AAA ratio affected the hippocampal concentration of monoamines [serotonin (5-HT), dopamine (DA) and noradrenaline (NA)]. Valproic acid (VPA) administration potently modified the balance between the BCAA and AAA. In the brain, the significantly increased AAA and decreased BCAA concentrations were followed by a decrease in the BCAA/AAA ratio. In the plasma, VPA significantly decreased the BCAA and AAA levels. The changes in the BCAA and AAA levels were accompanied by an increase in the NA, DA and 5-HT levels as well as hippocampal 5-HT metabolism. This novel finding indicates that VPA, through the displacement of TRP from its protein-binding sites, could disturb the BCAA/AAA ratio, with central nervous system consequences, including the possible contribution to VPAs effects in affective disorders. PMID:24249529

Maciejak, Piotr; Szyndler, Janusz; Ko?osowska, Karolina; Turzy?ska, Danuta; Sobolewska, Alicja; Walkowiak, Jerzy; P?a?nik, Adam

2014-05-01

215

Chemical and Enzymatic Stability of Amino acid Prodrugs Containing Methoxy, Ethoxy and Propylene Glycol Linkers  

PubMed Central

Purpose To evaluate the chemical and enzymatic stabilities of methoxy, ethoxy and propylene glycol linker containing prodrugs in order to find a suitable linker for prodrugs of carboxylic acids with amino acids. Methods L-valine and L-phenylalanine prodrugs of model compounds (benzoic acid and phenyl acetic acid) containing methoxy, ethoxy and propylene glycol linkers were synthesized. The hydrolysis rate profile of each compound was studied at physiologically relevant pHs (1.2, 4, 6 and 7.4). Enzymatic hydrolysis of propylene glycol containing compounds was studied using Caco-2 homogenate as well as purified enzymes, valacyclovirase. Results It was observed that the stability of the prodrugs increases with the linker length (propyl>ethyl>methyl). The model prodrugs were stable at acidic pH as compared to basic pH. It was observed that the prodrug with the aliphatic amino acid promoiety was more stable as compared to its aromatic counterpart. The comparison between benzyl and the phenyl model compounds revealed that the amino acid side chain is significant in determining the stability of the prodrug whereas the benzyl or phenyl carboxylic acid had little or no effect on the stability. The enzymatic activation studies of propylene glycol linker prodrug in presence of valacyclovirase and cell homogenate showed faster generation of the parent drug at pH 7.4. The half life of prodrugs at pH 7.4 was more than 12 hours, whereas in presence of cell homogenate the half lives were less than 1 hour. Hydrolysis by Caco-2 homogenate generated the parent compound in two steps, where the prodrug was first converted to the intermediate, propylene glycol benzoate, which was then converted to the parent compound (benzoic acid). Enzymatic hydrolysis of propylene glycol containing prodrugs by valacyclovirase showed hydrolysis of the amino acid ester part to generate the propylene glycol ester of model compound (propylene glycol benzoate) as the major product. Conclusion The methoxy linker containing amino acid prodrugs were the least stable while propylene glycol linker containing prodrugs were most stable. This work suggests that the propylene glycol linker is an optimal linker for amino acids prodrugs since it has good chemical stability and is enzymatically hydrolyzed to yield the parent drug. This approach can be further extended to other non-amino acid prodrugs and to provide a chemical handle to modify lead molecules containing carboxylic group(s). PMID:19566080

Gupta, Deepak; Gupta, Sheeba Varghese; Lee, Kyung-Dall; Amidon, Gordon L.

2012-01-01

216

The effect of fasting and the dietary levels of vitamins on the concentration of free amino acids in the plasma and tissues of chicks  

E-print Network

Charkey, Kano and Hougham (1955) determined the free amino acids in blood of adult humans which had been fasted 48 hours There was an increase in the level of leucine and valine, and a simultaneous decrease in the level of lysine, threonine, methionine... significantly when the diet was low in biotin. This observation has been confirmed in the present studies./ Charkey, Wilgus, Patton^ Glassner (1950) studied the effect, of vita? min on t^ie concentration of free amino acid in the blood plasma of the chicks...

Notani, Gursaran Wadhumal

2013-10-04

217

L-Glutamine regulates amino acid utilization by intestinal bacteria.  

PubMed

Catabolism of amino acids (AA) by intestinal bacteria greatly affects their bioavailability in the systemic circulation and the health of animals and humans. This study tests the novel hypothesis that L-glutamine regulates AA utilization by luminal bacteria of the small intestine. Pure bacterial strains (Streptococcus sp., Escherichia coli and Klebsiella sp.) and mixed bacterial cultures derived from the jejunum or ileum of pigs were cultured in the presence of 0-5 mM L-glutamine under anaerobic conditions. After 3 h of incubation, samples were taken for the determination of AA utilization. Results showed concentration-dependent increases in the utilization of glutamine in parallel with the increased conversion of glutamine into glutamate in all the bacteria. Complete utilization of asparagine, aspartate and serine was observed in pure bacterial strains after the 3-h incubation. The addition of glutamine reduced the net utilization of asparagine by both jejunal and ileal mixed bacteria. Net utilization of lysine, leucine, valine, ornithine and serine by jejunal or ileal mixed bacteria decreased with the addition of glutamine in a concentration-dependent manner. Collectively, glutamine dynamically modulates the bacterial metabolism of the arginine family of AA as well as the serine and aspartate families of AA and reduced the catabolism of most AA (including nutritionally essential and nonessential AA) in jejunal or ileal mixed bacteria. The beneficial effects of glutamine on gut nutrition and health may involve initiation of the signaling pathways related to AA metabolism in the luminal bacteria of the small intestine. PMID:22451274

Dai, Zhao-Lai; Li, Xi-Long; Xi, Peng-Bin; Zhang, Jing; Wu, Guoyao; Zhu, Wei-Yun

2013-09-01

218

Unnatural amino acids in novel antibody conjugates.  

PubMed

Antibody-drug conjugates are an important and emerging drug class for the treatment of cancer. Recent evidence strongly suggests that site-specific drug conjugation results in a homogenous population of molecules with more favorable activity and pharmacokinetic properties than randomly conjugated antibodies. Unnatural amino acids (uAAs) can be incorporated in recombinant proteins to enable unique orthogonal chemistries in comparison to the side chains of the natural 20 amino acids. Thus, uAAs present a novel platform for which to create next-generation antibody-drug conjugates. Furthermore, site-specific conjugation through uAAs can also enpower unique small molecule, bispecific, multispecific and other conjugates that could be important constructs for therapeutics, diagnostics and research reagents. Here, we review the progress in uAA incorporation and conjugate construction through both cell-based and -free approaches. PMID:25163001

Hallam, Trevor J; Smider, Vaughn V

2014-07-01

219

FgIlv5 is required for branched-chain amino acid biosynthesis and full virulence in Fusarium graminearum.  

PubMed

In this study, we characterized FgIlv5, a homologue of the Saccharomyces cerevisiae keto-acid reductoisomerase (KARI) from the important wheat head scab fungus Fusarium graminearum. KARI is a key enzyme in the branched-chain amino acid (BCAA, including leucine, isoleucine and valine) biosynthetic pathway that exists in a variety of organisms from bacteria to fungi and higher plants, but not in mammals. The FgILV5 deletion mutant ?FgIlv5-4 failed to grow when the culture medium was nutritionally limited for BCAAs. When grown on potato-dextrose agar plates, ?FgIlv5-4 exhibited a significant decrease in aerial hyphae formation and red pigmentation. Conidia formation was also blocked in ?FgIlv5-4. Exogenous addition of 1 mM isoleucine and valine was able to rescue the defects of mycelial growth and conidial morphogenesis. Cellular stress assays showed that ?FgIlv5-4 was more sensitive to osmotic and oxidative stresses than the wild-type strain. In addition, virulence of ?FgIlv5-4 was dramatically reduced on wheat heads, and a low level of deoxynivalenol production was detected in ?FgIlv5-4 in wheat kernels. The results of this study indicate that FgIlv5 is involved in valine and isoleucine biosynthesis and is required for full virulence in F. graminearum. PMID:24493249

Liu, Xin; Wang, Jian; Xu, Jianhong; Shi, Jianrong

2014-04-01

220

Amino acids and osmolarity in honeybee drone haemolymph  

Microsoft Academic Search

Summary In the haemolymph of honeybee drones, concentrations of free amino acids were higher than in worker haemolymph, with different relative proportions of individual amino acids. The overall concentration of free amino acids reached its highest level at the 5th day after adult drone emergence, and after the 9th day only minor changes in the concentration and distribution of free

B. Leonhard; K. Crailsheim

1999-01-01

221

Analysis of free amino acids in green coffee beans  

Microsoft Academic Search

To investigate amino acid changes in green coffee beans in the post-harvest period, amino acid concentrations were determined in green beans and after modelled drying, fermentation and storage. After the drying at alternating temperatures up to maximally 40°C, considerable changes in the concentrations of individual amino acids were identified. At the beginning of the storage period, significant changes in concentration

Ulrike Arnold; Eberhard Ludwig

1996-01-01

222

Proteins: From Structural Classification to Amino Acid Interaction Networks  

E-print Network

Proteins: From Structural Classification to Amino Acid Interaction Networks O. GACI LITIS are the protein's amino acids and whose edges are the inter- actions between them. Using a graph theory approach: proteins, amino acid, interaction network, structural classification 1 Introduction Proteins are biological

Boyer, Edmond

223

Original article Comparison of nucleic and amino acid sequences and  

E-print Network

Original article Comparison of nucleic and amino acid sequences and phylogenetic analysis of open was investigated. Nucleic and deduced amino acid sequences from seven different EAV isolates (one European, one reference strain. ORF 3 nucleotide and amino acid sequence identities between these isolates (including

Boyer, Edmond

224

Stochastic Analysis of Amino Acid Substitution in Protein Synthesis  

E-print Network

Stochastic Analysis of Amino Acid Substitution in Protein Synthesis D. Bosnacki1 , H.M.M. ten present a formal analysis of amino acid replacement dur- ing mRNA translation. Building on an abstract of the insertion of amino acids into the nascent polypeptide chain. To this end, we integrate the probabilistic

de Vink, Erik

225

Highly Efficient Synthesis of Chiral -Amino Acid Derivatives via  

E-print Network

Highly Efficient Synthesis of Chiral -Amino Acid Derivatives via Asymmetric Hydrogenation Wenjun-TangPhos complex is an efficient hydrogenation catalyst for making chiral -amino acid derivatives. With the Rh -amino acids has drawn a great deal of attention due to its importance in biomedical research

Zhang, Xumu

226

Original article Whole blood and plasma amino acid transfers across  

E-print Network

Original article Whole blood and plasma amino acid transfers across the portal drained viscera (WB) and plasma (P) amino acid transfers across the portal drained viscera and the liver were amino acid concentrations were determined in the CA, PV and HV. The plasma/WB ratios showed

Paris-Sud XI, Université de

227

Exploring the Overproduction of Amino Acids Using the Bilevel Optimization  

E-print Network

Exploring the Overproduction of Amino Acids Using the Bilevel Optimization Framework OptKnock Priti of representative amino acids and key precursors for all five families. These strat- egies span not only the central metabolic network genes but also the amino acid biosynthetic and degradation pathways. In addition to gene

Maranas, Costas

228

ASTROCHEMISTRY Radiolysis and radioracemization of 20 amino acids  

E-print Network

ASTROCHEMISTRY Radiolysis and radioracemization of 20 amino acids from the beginning of the Solar-Verlag 2011 Abstract A series of chiral amino acids in the levo form used in the current terrestrial. For each amino acids, the radiolysis degree and the radioracemization degree was measured, respectively

229

Chemoenzymatic Synthesis of Unnatural Amino Acids via Modified Claisen  

E-print Network

Chemoenzymatic Synthesis of Unnatural Amino Acids via Modified Claisen Rearrangement of Glycine functionalized R-cyclo- hexenyl amino acid such as 2, obtained via a [3,3]-sig- matropic rearrangement in our first publication in this area.7 The first synthesis of amino acids by Claisen rearrangement

Hudlicky, Tomas

230

Amino Acids DOI: 10.1002/anie.200602801  

E-print Network

Amino Acids DOI: 10.1002/anie.200602801 Catalytic, Asymmetric Synthesis of 1,4- Benzoxazinones: A Remarkably Enantioselective Route to a-Amino Acid Derivatives from o-Benzoquinone Imides** Jamison Wolfer enantiomeri- cally enriched a-amino acids and related derivatives.[4] Herein, we present the first catalytic

Lectka, Thomas

231

Jacobs University Bremen Encoding of Amino Acids and Proteins  

E-print Network

Jacobs University Bremen Encoding of Amino Acids and Proteins from a Communications and Information School of Engineering and Science Encoding of Amino Acids and Proteins from a Communications). The 2-D plots of ECM show that most mutations occur between codons that encode the same amino acid, i

Henkel, Werner

232

Reconstructing Amino Acid Interaction Networks by an Ant Colony Approach  

E-print Network

Reconstructing Amino Acid Interaction Networks by an Ant Colony Approach Omar GACI and Stefan BALEV are the proteins amino acids and whose edges are the interactions between them. We consider the problem of reconstructing protein's interaction network from its amino acid sequence. We rely on a probability that two

Paris-Sud XI, Université de

233

Racemic amino acids from the ultraviolet photolysis of  

E-print Network

.............................................................. Racemic amino acids from for the origin and early evolution of life1 . Indigenous amino acids have been found in meteorites2 --over 70 in the Murchison meteorite alone3 . Although it has been generally accepted that the meteoritic amino acids formed

234

Chemical Genetic Programming The Effect of Evolving Amino Acids  

E-print Network

Chemical Genetic Programming ­ The Effect of Evolving Amino Acids Wojciech Piaseczny1 , Hideaki of amino acids is prepared, mainly through assimilation of smaller inorganic compounds in plants, and through digestion of food in animals. Each amino acid is a bio- chemical building block, so together

Fernandez, Thomas

235

Origin, Microbiology, Nutrition, and Pharmacology of D-Amino Acids  

Technology Transfer Automated Retrieval System (TEKTRAN)

Exposure of food proteins to certain processing conditions induces two major chemical changes: racemization of all L-amino acids (LAA) to D-amino acids (DAA) and concurrent formation of crosslinked amino acids such as lysinoalanine (LAL). The diet contains both processing-induced and naturally-form...

236

Efficient Synthesis of Enantiopure -Amino--Keto Acids from  

E-print Network

Efficient Synthesis of Enantiopure -Amino--Keto Acids from L-Homoserine Anil K. Sharma and Paul J hergenro@uiuc.edu Received March 26, 2003 ABSTRACT A variety of -amino--keto acids were prepared in four-catalyzed Grignard addition to a N-protected derivative of L-homoserine. One of the -amino--keto acids was then used

Hergenrother, Paul J.

237

Protein structures uncovered Amino acids are molecules and are the  

E-print Network

Protein structures uncovered Lysozyme Amino acid Amino acids are molecules and are the building blocks of proteins. Human proteins contain 20 different kinds of amino acids, which are represented below to form a chain. This chain is called the primary structure. If the protein chain doesn't occur

Rambaut, Andrew

238

Regulatory Roles of Amino Acids in Immune Response  

Microsoft Academic Search

Amino acids are not only the building blocks of proteins but are also key regulators of various pathological and physiological processes, including immune responses, in living cells. However, the mechanisms responsible for these effects of amino acids are largely unknown. The regulatory roles of amino acids in the immune system can be considered from two perspectives, namely, the enhancement of

Junya Yoneda; Ayatoshi Andou; Kenji Takehana

2009-01-01

239

Regulation of yeast acetohydroxyacid synthase by valine and ATP.  

PubMed Central

The first step in the common pathway for the biosynthesis of branched-chain amino acids is catalysed by acetohydroxyacid synthase (AHAS; EC 4.1.3.18). The enzyme is found in plants, fungi and bacteria, and is regulated by controls on transcription and translation, and by allosteric modulation of catalytic activity. It has long been known that the bacterial enzyme is composed of two types of subunit, and a similar arrangement has been found recently for the yeast and plant enzymes. One type of subunit contains the catalytic machinery, whereas the other has a regulatory function. Previously, we have shown [Pang and Duggleby (1999) Biochemistry 38, 5222--5231] that yeast AHAS can be reconstituted from its separately purified subunits. The reconstituted enzyme is inhibited by valine, and ATP reverses this inhibition. In the present work, we further characterize the structure and the regulatory properties of reconstituted yeast AHAS. High phosphate concentrations are required for reconstitution and it is shown that these conditions are necessary for physical association between the catalytic and regulatory subunits. It is demonstrated by CD spectral changes that ATP binds to the regulatory subunit alone, most probably as MgATP. Neither valine nor MgATP causes dissociation of the regulatory subunit from the catalytic subunit. The specificity of valine inhibition and MgATP activation are examined and it is found that the only effective analogue of either regulator of those tested is the non-hydrolysable ATP mimic, adenosine 5'-[beta,gamma-imido]triphosphate. The kinetics of regulation are studied in detail and it is shown that the activation by MgATP depends on the valine concentration in a complex manner that is consistent with a proposed quantitative model. PMID:11463345

Pang, S S; Duggleby, R G

2001-01-01

240

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

241

Adult bile acid amino transferase deficiency  

PubMed Central

Patient: Female, 70 Final Diagnosis: Bile acid amino transferase deficiency Symptoms: Headache • indigestion • itching skin • nausea • vomiting Medication: — Clinical Procedure: — Specialty: Gastroenterology and Hepatology Objective: Challenging differential diagnosis Background: Bile acid synthesis impairments are difficult to diagnose due to non-specific manifestations related to progressive failure to absorb essential fatty acids and fat soluble vitamins and failure to maintain normal intestinal microbiota. Case Report: A 70-year-old female presented with long-standing history of recurrent headaches, indigestion, dry, scaly, itching skin, and fluid around knee joints. Quantitative Electroencephalography (QEEG) revealed widespread excess theta maximum in the temporal regions. A rare pattern of elevated plasma glycine and taurine led to suspicion of BAATD. A stool profile employing molecular probes for commensal bacteria revealed elevation of Fusobacteria spp. Implementation of bile acid replacement therapy (BART) produced rapid remission of headache and other symptoms and a three-month follow up stool profile revealed normalization of fecal Fusobacteria populations that remained normal after one year of BART. QEEG analyses 4 weeks following BART showed evidence of significant improvement in CNS functioning. Conclusions: This case illustrates the potential for diagnosis of latent, adult BAATD by finding a unique pattern of plasma amino acids and monitoring of therapy by observing normalization of fecal commensal bacteria and functional brain assessments. PMID:24587851

Lord, Richard S.; Tuttle, Daniel M.; Cantor, David S.

2014-01-01

242

Amino acid and vascular endothelial growth factor levels in subretinal fluid in rhegmatogenous retinal detachment  

PubMed Central

Purpose To study the concentrations of amino acids and vascular endothelial growth factor (VEGF) in subretinal fluid (SRF) of cases with rhegmatogenous retinal detachment (RRD). The relevance of the results with postoperative anatomic and functional success in RRD was investigated. Methods Fifty-three patients were included in this prospective study. The study group consisted of 46 patients who had scleral buckling surgery with the diagnosis of RRD, and SRF was obtained during the surgery. The control specimens consisted of vitreous samples of seven patients who were diagnosed with pars plana vitrectomy without RRD. Study cases were divided into three groups, corresponding to the duration of retinal detachment. Clinical characteristics, including best corrected visual acuity (BCVA) and anatomic status at month 6, were recorded. Concentrations of 15 selected amino acids were quantified by using high performance liquid chromatography, and VEGF levels were measured with enzyme immunoassay. Results When compared with the control group, SRF concentrations of aspartate, citrulline, glutamate, and glycine increased significantly in the study group (p<0.05). Statistical analysis showed that concentrations of alanine, isoleucine, leucine, methionine, phenylalanine, threonine, tyrosine, and valine decreased (p<0.05). SRF levels of glutamine, taurine, and serine had no significant change. SRF VEGF levels were significantly higher than the vitreous samples of the controls (p<0.001). Time-dependent changes and interactions between VEGF and amino acids were observed. There was no correlation between the concentrations of amino acids or VEGF with the parameters of BCVA and anatomical success. Conclusions Significant changes occur in concentrations of amino acids and VEGF in SRF of cases with RRD. Our results suggest that several mechanisms contribute to the pathophysiology. PMID:25352742

Buyukuysal, Rifat Levent; Gelisken, Oner; Buyukuysal, Cagatay; Can, Basak

2014-01-01

243

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

244

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

PubMed Central

Autoradiographs were prepared from frozen sections of everted sacs of hamster jejunum which had been incubated in vitro with C14- or H3-labeled sugars and amino acids. When such tissue was incubated in 1 mM solutions of L-valine or L-methionine, columnar absorptive cells at tips of villi accumulated these amino acids to concentrations ranging from 5 to 50 millimoles per liter of cells. Quantitative data were obtained by microdensitometry of C14 autoradiographs. Similar, though less striking, results were obtained with the sugars: galactose, 3-0-methylglucose, ?-methylglucoside, and 6-deoxyglucose. In all cases the marked "step-up" in concentration occurred near the brush border of the cell, and a "step-down" in concentration occurred at the basal pole of the cell. Known inhibitors of intestinal absorption, e.g., phlorizin in the case of sugars, blocked the concentrative step at the luminal border of the absorptive cell. It is inferred from these data that active transport systems for sugars and amino acids reside in the brush border region of the cell. Additional evidence suggests that the basal membrane of the cell may be the site of both a diffusion barrier and a weak transport system directed into the cell. PMID:19866662

Kinter, William B.; Wilson, T. Hastings

1965-01-01

245

A study of protein structure using amino acid interaction networks 1 A study of protein structure using amino acid  

E-print Network

A study of protein structure using amino acid interaction networks 1 X A study of protein structure using amino acid interaction networks Omar Gaci and Stefan Balev University of Le Havre France 1 of interacting amino acids. We believe that understanding these networks can help to better understand

Paris-Sud XI, Université de

246

Time-Resolved Transcriptome Analysis of Bacillus subtilis Responding to Valine, Glutamate, and Glutamine  

PubMed Central

Microorganisms can restructure their transcriptional output to adapt to environmental conditions by sensing endogenous metabolite pools. In this paper, an Agilent customized microarray representing 4,106 genes was used to study temporal transcript profiles of Bacillus subtilis in response to valine, glutamate and glutamine pulses over 24 h. A total of 673, 835, and 1135 amino-acid-regulated genes were identified having significantly changed expression at one or more time points in response to valine, glutamate, and glutamine, respectively, including genes involved in cell wall, cellular import, metabolism of amino-acids and nucleotides, transcriptional regulation, flagellar motility, chemotaxis, phage proteins, sporulation, and many genes of unknown function. Different amino acid treatments were compared in terms of both the global temporal profiles and the 5-minute quick regulations, and between-experiment differential genes were identified. The highlighted genes were analyzed based on diverse sources of gene functions using a variety of computational tools, including T-profiler analysis, and hierarchical clustering. The results revealed the common and distinct modes of action of these three amino acids, and should help to elucidate the specific signaling mechanism of each amino acid as an effector. PMID:19763274

Ye, Bang-Ce; Zhang, Yan; Yu, Hui; Yu, Wen-Bang; Liu, Bao-Hong; Yin, Bin-Cheng; Yin, Chun-Yun; Li, Yuan-Yuan; Chu, Ju; Zhang, Si-Liang

2009-01-01

247

Computational model of abiogenic amino acid condensation to obtain a polar amino acid profile.  

PubMed

In accordance with the second law of thermodynamics, the Universe as a whole tends to higher entropy. However, the sequence of far-from-equilibrium events that led to the emergence of life on Earth could have imposed order and complexity during the course of chemical reactions in the so-called primordial soup of life. Hence, we may expect to find characteristic profiles or biases in the prebiotic product mixtures, as for instance among the first amino acids. Seeking to shed light on this hypothesis, we have designed a high performance computer program that simulates the spontaneous formation of the amino acid monomers in closed environments. The program was designed in reference to a prebiotic scenario proposed by Sydney W. Fox. The amino acid abundances and their polarities as the two principal biases were also taken into consideration. We regarded the computational model as exhaustive since 200,000 amino acid dimers were formed by simulation, subsequently expressed in a vector and compared with the corresponding amino acid dimers that were experimentally obtained by Fox. We found a very high similarity between the experimental results and our simulations. PMID:24809066

Polanco, Carlos; Buhse, Thomas; Samaniego, José Lino; Castañón González, Jorge Alberto; Arias Estrada, Miguel

2014-01-01

248

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 alpha-amino-epsilon-caprolactam racemase.  

PubMed

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 alpha-amino-epsilon-caprolactam racemase from Achromobacter obae as the catalyst by dynamic kinetic resolution of amino acid amides. PMID:17586677

Yamaguchi, Shigenori; Komeda, Hidenobu; Asano, Yasuhisa

2007-08-01

249

Amino-Terminal Amino Acid Sequence of the Silkworm Prothoracicotropic Hormone: Homology with Insulin  

Microsoft Academic Search

Three molecular forms of prothoracicotropic hormone were isolated from the head of the adult silkworm, Bombyx mori, and the amino acid sequence of 19 amino acid residues in the amino terminus of these prothoracicotropic hormones was determined. These residues exhibit significant homology with insulin and insulin-like growth factors.

Hiromichi Nagasawa; Hiroshi Kataoka; Akira Isogai; Saburo Tamura; Akinori Suzuki; Hironori Ishizaki; Akira Mizoguchi; Yuko Fujiwara; Atsushi Suzuki

1984-01-01

250

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

2012-07-01

251

on Amino Acids Henrik SvennerstamAmino Acid Uptake in Arabidopsis-the Transporters Involved, Kinetics of Uptake and Growth on Amino Acids  

E-print Network

Doctoral Thesis No. 2008:50 Plants are known to have the ability to take up amino acids from the soil solution and use them as a source of nitrogen. In this thesis, two transporters involved in Arabidopsis amino acid uptake were identified, LHT1 and AAP5, each responsible for the uptake of a specific spectrum of amino acids. Mutant plants, either lacking or over-expressing the identified transporters were found to be affected in both the uptake of- and in the case of LHT1, growth on amino acids.

Acta Universitatis Agriculturae Sueciae; Acta Universitatis; Agriculturae Sueciae; Henrik Svennerstam

252

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

253

Amino acid enantiomer excesses in meteorites: origin and significance  

NASA Astrophysics Data System (ADS)

The presence of small l-excesses in both of the two enantiomeric pairs of 2-amino-2,3-dimethylpentanoic acid, in 2-amino-2-methylbutanoic acid (Isovaline), and in 2-amino-2-methylpentanoic acid from the Murchison meteorite has also been observed in these amino acids as extracted from the Murray meteorite. As in Murchison, the ?-hydrogen analogues of the latter amino acids, 2-amino butanoic acid and 2-amino pentanoic acid, were found to be racemates. In addition, l-excesses were observed in 2-amino-2,3-dimethylbutanoic acid and 2-amino-2-methylhexanoic acid from both the Murchison and Murray meteorites. The l-excesses observed in the amino acids from Murray were smaller than those found in their Murchison analogues. The substantial excess of l-alanine reported by others was not observed in fractionated (reverse-phase chromatography) extracts of either Murchison or Murray. Several amino acids were identified in the Murchison extract that can interfere with determination of the alanine enantiomer ratio on Chirasil-L-Val unless removed by a prior fractionation step. The role of ultraviolet circularly polarized light in generating meteorite enantiomeric excesses and the possible significance of such excesses to the origin of terrestrial homochirality are discussed.

Cronin, J. R.; Pizzarello, S.

1999-01-01

254

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

255

Isotope composition of carbon in amino acids of solid bitumens  

NASA Astrophysics Data System (ADS)

Primary data are presented on the isotope composition of carbon in individual amino acids from solid bitumens and several biological objects. The amino acids of biological objects are characterized by wide variations of the isotope composition of carbon. This fact occurs owing to the difference in biochemical paths of metabolism resulting in the synthesis of individual amino acids. The ?13C values are somewhat decreased for individual amino acids in asphaltenes, varying from -7.7 to -31.7‰. The carbon of amino acids is weighted in kerits from Bad'el' compared to asphaltenes. All the natural bitumens retain the characteristic trend for natural substances: the isotopically heavy and light amino acids by carbon are glycine and leucine, respectively. The isotope composition of amino-acid carbon is lightened compared to natural bitumens in the samples formed under a pronounced thermal impact (asphalt-like crust and kirishite).

Shanina, S. N.; Bushnev, D. A.

2014-06-01

256

(L)- or (D)-valine tert-butylamide grafted on permethylated beta-cyclodextrin derivatives as new mixed binary chiral selectors: versatile tools for capillary gas chromatographic enantioseparation.  

PubMed

This work deals with the synthesis of two mixed binary chiral selectors prepared by grafting (L)- or (D)-valine tert-butylamide on permethylated cyclodextrin macrocycle. The enantioselective properties of the new chiral selectors diluted in OV11 polysiloxane (35% phenyl- and 65% methylsiloxane) were investigated by means of injections of 117 racemic mixtures. The mixed chiral selectors with (L)-valine and, to a lesser extent with (D)-valine, were found to have an improved enantioselectivity toward amino acid derivatives by comparison to permethylated cyclodextrin. The enantioseparation capability of these new chiral selectors has proven to be slightly less efficient than Chirasil-L-Val (Alltech) for amino acid derivatives, but it has been extended to include terpenes, lactones, esters, aliphatic compounds and aryl alcohols. PMID:19303600

Stephany, O; Dron, F; Tisse, S; Martinez, A; Nuzillard, J-M; Peulon-Agasse, V; Cardinaël, P; Bouillon, J-P

2009-05-01

257

Substrate specificity of L-delta-(alpha-aminoadipoyl)-L-cysteinyl-D-valine synthetase from Cephalosporium acremonium: demonstration of the structure of several unnatural tripeptide products.  

PubMed Central

Potential substrates for L-delta-(alpha-aminoadipoyl)-L-(cysteinyl)-D-valine (ACV) synthetase were initially identified using both the amino-acid-dependent ATP<-->pyrophosphate exchange reaction catalysed by the enzyme and the incorporation of 14C-radiolabelled cysteine and valine into potential peptide products. S-Carboxymethylcysteine was an effective substitute for alpha-aminoadipate and both allylglycine and vinylglycine could substitute for cysteine, indicating that the thiol group of cysteine is not essential for peptide formation. L-allo-Isoleucine but not L-isoleucine substituted effectively for valine. The structures of the presumed peptide products derived from these amino acids were confirmed by combined use of electrospray-ionization m.s. (e.s.m.s.) and 1H n.m.r. These results clearly indicate that, in common with other peptide synthetases, but in contrast with ribosomal peptide synthesis, ACV synthetase has a relatively broad substrate specificity. PMID:8042979

Baldwin, J E; Shiau, C Y; Byford, M F; Schofield, C J

1994-01-01

258

Evolutionary Systems Biology of Amino Acid Biosynthetic Cost in Yeast  

PubMed Central

Every protein has a biosynthetic cost to the cell based on the synthesis of its constituent amino acids. In order to optimise growth and reproduction, natural selection is expected, where possible, to favour the use of proteins whose constituents are cheaper to produce, as reduced biosynthetic cost may confer a fitness advantage to the organism. Quantifying the cost of amino acid biosynthesis presents challenges, since energetic requirements may change across different cellular and environmental conditions. We developed a systems biology approach to estimate the cost of amino acid synthesis based on genome-scale metabolic models and investigated the effects of the cost of amino acid synthesis on Saccharomyces cerevisiae gene expression and protein evolution. First, we used our two new and six previously reported measures of amino acid cost in conjunction with codon usage bias, tRNA gene number and atomic composition to identify which of these factors best predict transcript and protein levels. Second, we compared amino acid cost with rates of amino acid substitution across four species in the genus Saccharomyces. Regardless of which cost measure is used, amino acid biosynthetic cost is weakly associated with transcript and protein levels. In contrast, we find that biosynthetic cost and amino acid substitution rates show a negative correlation, but for only a subset of cost measures. In the economy of the yeast cell, we find that the cost of amino acid synthesis plays a limited role in shaping transcript and protein expression levels compared to that of translational optimisation. Biosynthetic cost does, however, appear to affect rates of amino acid evolution in Saccharomyces, suggesting that expensive amino acids may only be used when they have specific structural or functional roles in protein sequences. However, as there appears to be no single currency to compute the cost of amino acid synthesis across all cellular and environmental conditions, we conclude that a systems approach is necessary to unravel the full effects of amino acid biosynthetic cost in complex biological systems. PMID:20808905

Barton, Michael D.; Delneri, Daniela; Oliver, Stephen G.; Rattray, Magnus; Bergman, Casey M.

2010-01-01

259

Running Head: Amino acid inhibition of Agrp gene expression  

E-print Network

Metabolic fuels act on hypothalamic neurons to regulate feeding behavior and energy homeostasis, but the signaling mechanisms mediating these effects are not fully clear. Rats placed on a low protein diet (10 % of calories) exhibited increased food intake (P amino acid mixture (RPMI 1640) or leucine alone (1 ug) suppressed 24h food intake (P amino acids concentrations within the brain is sufficient to suppress food intake. To define a cellular mechanism for these direct effects, GT1-7 hypothalamic cells were exposed to low amino acids for 16hrs. Decreasing amino acid availability increased Agrp mRNA levels in GT1-7 cells (P amino acid leucine (P amino acid concentrations increased S6K phosphorylation via a rapamycin-sensitive mechanism, suggesting that amino acids directly stimulated mTOR signaling. To test whether mTOR signaling contributes to amino acid inhibition of Agrp gene expression, GT1-7 cells cultured in either low or high amino acids for 16hrs and were also treated with rapamcyin (50 nM). Rapamycin treatment increased Agrp mRNA levels in cells exposed to high amino acids (P = 0.01). Taken together, these observations indicate that amino

Christopher D. Morrison; Xiaochun Xi; Christy L. White; Jianping Ye; Roy J. Martin; Neurosignaling Laboratory; Roy J Martin

260

Accumulated analyses of amino acid precursors in returned lunar samples  

NASA Technical Reports Server (NTRS)

Six amino acids (glycine, alanine, aspartic acid, glutamic acid, serine, and threonine) obtained by hydrolysis of extracts have been quantitatively determined in ten collections of fines from five Apollo missions. Although the amounts found, 7-45 ng/g, are small, the lunar amino acid/carbon ratios are comparable to those of the carbonaceous chondrites, Murchison and Murray, as analyzed by the same procedures. Since both the ratios of amino acid to carbon, and the four or five most common types of proteinous amino acid found, are comparable for the two extraterrestrial sources despite different cosmophysical histories of the moon and meteorites, common cosmochemical processes are suggested.

Fox, S. W.; Harada, K.; Hare, P. E.

1973-01-01

261

NUTRITIONAL AND FUNCTIONAL IMPORTANCE OF INTESTINAL SULFUR AMINO ACID METABOLISM  

Technology Transfer Automated Retrieval System (TEKTRAN)

The metabolism of sulfur amino acids, methionine and cysteine, has been linked to several key aspects of human health and cellular function. In addition, the metabolism of dietary amino acids by the gastrointestinal tract is nutritionally important for normal function. In the case of sulfur amino ac...

262

Synthesis of alpha-amino acids  

DOEpatents

A method for synthesizing alpha amino acids proceding 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 snythesis methods of the prior art.

Davis, Jr., Jefferson W. (San Francisco, CA)

1983-01-01

263

Synthesis of alpha-amino acids  

DOEpatents

A method 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 12 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, Jr., Jefferson W. (San Francisco, CA)

1983-01-01

264

Synthesis of alpha-amino acids  

DOEpatents

A method for synthesizing alpha amino acids proceding 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 12 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, Jr., Jefferson W. (San Francisco, CA)

1983-01-01

265

Identification, Purification, and Characterization of a Novel Amino Acid Racemase, Isoleucine 2-Epimerase, from Lactobacillus Species  

PubMed Central

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

2013-01-01

266

Mutual inhibition of incorporation into protein of branched-chain amino acids in brain homogenates of developing and adult rats.  

PubMed

The mutual inhibitory effect of an excess of leucine, isoleucine and valine on their incorporation into protein was studied with brain homogenates prepared from 1-, 7-, 14- and 90-day-old rats. All these branched-chain amino acids diminished each other's incorporation, leucine being slightly more potent in this respect. The inhibition was the stronger the younger were the experimental animals. An attempt was made to analyze with a digital computer the kinetics of inhibition of incorporation by fitting the experimental data by the Hill equation ?/V = s(n)/(K + s(n)). Mutual competition appears to occur, but the maximal velocity of incorporation was also in many cases diminished by these amino acids. PMID:20487942

Pajari, M; Oja, S S

1983-01-01

267

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

268

Synthesis, Chemical and Enzymatic Hydrolysis, and Aqueous Solubility of Amino Acid Ester Prodrugs of 3-Carboranyl Thymidine Analogues for Boron Neutron Capture Therapy of Brain Tumors  

PubMed Central

Various water-soluble L-valine-, L-glutamate-, and glycine ester prodrugs of two 3-Carboranyl Thymidine Analogues (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 to 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

2012-01-01

269

THIN-LAYER SEPARATION OF CITRIC ACID CYCLE INTERMEDIATES, LACTIC ACID, AND THE AMINO ACID TAURINE  

EPA Science Inventory

This paper describes a two-dimensional mixed-layer method for separating citric acid cycle intermediates, lactic acid and the amino acid taurine. The method cleanly separates all citric acid cycle intermediates tested, excepting citric acid and isocitric acid. The solvents are in...

270

Quantification of trimethylsilyl derivatives of amino acid disease biomarkers in neonatal blood samples by gas chromatography-mass spectrometry.  

PubMed

A novel analytical procedure was developed for the rapid determination of disease biomarkers of maple syrup urine disease (MSUD), L-valine, L-leucine, L-isoleucine, and L-phenylalanine in dried blood spots. Amino acids extracted from neonatal dried blood spots were rapidly derivatized with bis-(trimethylsilyl)trifluoroacetamide (BSTFA) and then analyzed by gas chromatography-mass spectrometry (GC-MS). Derivatization conditions and the method validation were studied: optimal derivatization conditions were acetonitrile as reaction solvent, a temperature of 100 degrees C, and a reaction time of 30 min. The proposed method provided a detection limit lower than 2.0 microM, recovery between 92% and 106%, and relative standard deviation less than 8.0%. The method was further tested in screening for neonatal MSUD by determination of L-valine, L-leucine, L-isoleucine, and L-phenylalanine in blood samples. The experimental results show that GC-MS following BSTFA derivatization is a rapid, simple, and sensitive method for the determination of amino acid disease biomarkers in blood samples, and is a potential tool for fast screening of MSUD. PMID:16385411

Shen, Xizhong; Deng, Chunhui; Wang, Ben; Dong, Ling

2006-02-01

271

Twenty natural amino acids identification by a photochromic sensor chip.  

PubMed

All 20 natural amino acids identification shows crucial importance in biochemistry and clinical application while it is still a challenge due to highly similarity in molecular configuration of the amino acids. Low efficiency, complicated sensing molecules and environment hindered the successful identification. Here, we developed a facile sensor chip composed of one photochromic molecule with metal ions spotted to form spirooxazine-metallic complexes, and successfully recognized all the 20 natural amino acids as well as their mixtures. The sensor chip gives distinct fluorescent fingerprint pattern of each amino acid, based on multistate of spirooxazine under different light stimulations and discriminated interaction between various metal ions and amino acids. The sensor chip demonstrates powerful capability of amino acids identification, which promotes sensing of biomolecules. PMID:25517682

Qin, Meng; Li, Fengyu; Huang, Yu; Ran, Wei; Han, Dong; Song, Yanlin

2015-01-20

272

Geochemistry of amino acids in shells of the clam Saxidomus  

USGS Publications Warehouse

Concentrations of amino acids and their corresponding d l enantiomeric ratios have been measured in shells of the bivalve mollusk Saxidomus from eleven localities, ranging in age from modern to probably more than 500,000 yr, along the Pacific coast of North America. Natural logarithms of amino acid concentrations correlate well with d l ratios, and the relationship provides a possible guide to the selection of fossils for use in amino acid dating. The relative order of the extents of racemization of amino acids at any given time appears to change with increasing sample age. Application of the amino acid dating method to shells from Whidbey Island, Washington, yields an age of about 80,000 yr, in contrast to the previously determined radiocarbon age of 36,000 yr which was measured on some shell carbonate and considered a minimum age. The amino acid age is compatible with the geologic record in the area. ?? 1980.

Kvenvolden, K.A.; Blunt, D.J.; McMenamin, M.A.; Straham, S.E.

1980-01-01

273

Diversity of amino acids in a typical chernozem of Moldova  

NASA Astrophysics Data System (ADS)

The content and composition of the amino acids in typical chernozems were studied. The objects of the study included a reference soil under an old fallow and three variants under fodder crop rotations: not fertilized, with mineral fertilizers, and with organic fertilizers. The contents of 18 amino acids were determined in these soils. The amino acids were extracted by the method of acid hydrolysis and identified by the method of ion-exchange chromatography. The total content of most of the amino acids was maximal in the reference soil; it was much lower in the cultivated soils and decreased in the following sequence: organic background > mineral background > no fertilization. The diversity of amino acids was evaluated quantitatively using different parameters applied in ecology for estimating various aspects of the species composition of communities (Simpson, Margalef, Menhinick, and Shannon's indices). The diversity and contribution of different amino acids to the total pool of amino acids also varied significantly in the studied variants. The maximum diversity of amino acids and maximum evenness of their relative abundance indices were typical of the reference chernozem; these parameters were lower in the cultivated soils. It was concluded that the changes in the structure of the amino acids under the impact of agricultural loads are similar to those that are usually observed under stress conditions.

Frunze, N. I.

2014-12-01

274

Survival of Amino Acids in Micrometeorites During Atmospheric Entry  

NASA Technical Reports Server (NTRS)

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 approx. 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. alpha-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 less than 550 C; all other amino acids apparently are destroyed. Key Words: Amino acids-Exogenous delivery-Micrometeorites-Sublimation.

Glavin, Daniel P.; Bada, Jeffrey L.

2003-01-01

275

Removal of acidic or basic ?-amino acids in water by poorly water soluble scandium complexes.  

PubMed

To recognize ?-amino acids with highly polar side chains in water, poorly water soluble scandium complexes with both Lewis acidic and basic portions were synthesized as artificial receptors. A suspension of some of these receptor molecules in an ?-amino acid solution could remove acidic and basic ?-amino acids from the solution. The compound most efficient at preferentially removing basic ?-amino acids (arginine, histidine, and lysine) was the receptor with 7,7'-[1,3-phenylenebis(carbonylimino)]bis(2-naphthalenesulfonate) as the ligand. The neutral ?-amino acids were barely removed by these receptors. Removal experiments using a mixed amino acid solution generally gave results similar to those obtained using solutions containing a single amino acid. The results demonstrated that the scandium complex receptors were useful for binding acidic and basic ?-amino acids. PMID:23050492

Hayashi, Nobuyuki; Jin, Shigeki; Ujihara, Tomomi

2012-11-01

276

Transport activity-dependent intracellular sorting of the yeast general amino acid permease  

E-print Network

Intracellular trafficking of the general amino acid permease, Gap1p, of Saccharomyces cerevisiae is regulated by amino acid abundance. When amino acids are scarce Gap1p is sorted to the plasma membrane, whereas when amino ...

Cain, Natalie Elaine

277

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. PMID:16663380

Secor, Jacob; Schrader, Larry E.

1984-01-01

278

Amino acid sequence of the human fibronectin receptor  

Microsoft Academic Search

The amino acid sequence deduced from eDNA of the human placental fibronectin receptor is reported. The receptor is composed of two subunits: an 0t subunit of 1,008 amino acids which is processed into two polypeptides disulfide bonded to one another, and a 13 subunit of 778 amino acids. Each subunit has near its COOH terminus a hydrophobic segment. This and

W. Scott Argraves; Shintaro Suzuki; Hiroharu Arai; Katie Thompson; Michael D. Pierschbacher; Erkki Ruoslahti

1987-01-01

279

Amino acids regulate the transcription, internal sorting, and intrinsic activity of the general amino acid permease (GAP1) in S. cerevisiae  

E-print Network

The high capacity general amino acid permease in Saccharomyces cerevisiae (GAP1) is regulated such that it actively imports amino acids into the cell from the extracellular medium only when internal amino acid levels are ...

Risinger, April L. (April Lynn)

2007-01-01

280

Cyclobutane amino acids and peptidomimetics, parallel catalyst screening for aziridination.  

E-print Network

??This thesis describes two projects: (i) syntheses and conformational studies of cyclobutane amino acids and peptidomimetics; and, (ii) parallel screening of catalysts for asymmetric aziridination.… (more)

Li, Shih-ming

2012-01-01

281

Kinetic Trapping of Metastable Amino Acid Polymorphs  

PubMed Central

Second harmonic generation (SHG) microscopy measurements indicate that inkjet-printed racemic solutions of amino acids can produce nanocrystals trapped in metastable polymorph forms upon rapid solvent evaporation. Polymorphism impacts the composition, distribution, and physicokinetic properties of organic solids, with energetic arguments favoring the most stable polymorph. In this study, unfavored noncentrosymmetric crystal forms were observed by SHG microscopy. Polarization-dependent SHG measurement and synchrotron X-ray microdiffraction analysis of individual printed drops are consistent with formation of homochiral crystal production. Fundamentally, these results provide evidence supporting the ubiquity of Ostwald’s Rule of Stages, describing the hypothesized transitioning of crystals between metastable polymorphic forms in the early stages of crystal formation. Practically, the presence of homochiral metastable forms has implications on chiral resolution and on solid form preparations relying on rapid solvent evaporation. PMID:24451055

Chowdhury, Azhad U.; Dettmar, Christopher M.; Sullivan, Shane Z.; Zhang, Shijie; Jacobs, Kevin T.; Kissick, David J.; Maltais, Thora; Hedderich, Hartmut G.; Bishop, Patricia A.; Simpson, Garth J.

2014-01-01

282

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

2012-07-14

283

Understanding and identifying amino acid repeats  

PubMed Central

Amino acid repeats (AARs) are abundant in protein sequences. They have particular roles in protein function and evolution. Simple repeat patterns generated by DNA slippage tend to introduce length variations and point mutations in repeat regions. Loss of normal and gain of abnormal function owing to their variable length are potential risks leading to diseases. Repeats with complex patterns mostly refer to the functional domain repeats, such as the well-known leucine-rich repeat and WD repeat, which are frequently involved in protein–protein interaction. They are mainly derived from internal gene duplication events and stabilized by ‘gate-keeper’ residues, which play crucial roles in preventing inter-domain aggregation. AARs are widely distributed in different proteomes across a variety of taxonomic ranges, and especially abundant in eukaryotic proteins. However, their specific evolutionary and functional scenarios are still poorly understood. Identifying AARs in protein sequences is the first step for the further investigation of their biological function and evolutionary mechanism. In principle, this is an NP-hard problem, as most of the repeat fragments are shaped by a series of sophisticated evolutionary events and become latent periodical patterns. It is not possible to define a uniform criterion for detecting and verifying various repeat patterns. Instead, different algorithms based on different strategies have been developed to cope with different repeat patterns. In this review, we attempt to describe the amino acid repeat-detection algorithms currently available and compare their strategies based on an in-depth analysis of the biological significance of protein repeats. PMID:23418055

Nijveen, Harm

2014-01-01

284

Amino acid fermentation at the origin of the genetic code.  

PubMed

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. PMID:22325238

de Vladar, Harold P

2012-01-01

285

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) PMID:22325238

2012-01-01

286

Modulation of Pseudomonas aeruginosa surface-associated group behaviors by individual amino acids through c-di-GMP signaling.  

PubMed

To colonize the cystic fibrosis lung, Pseudomonas aeruginosa establishes sessile communities referred to as biofilms. Although the signaling molecule c-di-GMP governs the transition from motile to sessile growth, the environmental signal(s) required to modulate biofilm formation remain unclear. Using relevant in vivo concentrations of the 19 amino acids previously identified in cystic fibrosis sputum, we demonstrated that arginine, ornithine, isoleucine, leucine, valine, phenylalanine and tyrosine robustly promoted biofilm formation in vitro. Among the seven biofilm-promoting amino acids, only arginine also completely repressed the ability of P. aeruginosa to swarm over semi-solid surfaces, suggesting that arginine may be an environmental cue favoring a sessile lifestyle. Mutating two documented diguanylate cyclases required for biofilm formation (SadC and RoeA) reduced biofilm formation and restored swarming motility on arginine-containing medium. Growth on arginine increased the intracellular levels of c-di-GMP, and this increase was dependent on the SadC and RoeA diguanylate cyclases. Strains mutated in sadC, roeA or both also showed a reduction in biofilm formation when grown with the other biofilm-promoting amino acids. Taken together, these results suggest that amino acids can modulate biofilm formation and swarming motility, at least in part, by controlling the intracellular levels of c-di-GMP. PMID:21554951

Bernier, Steve P; Ha, Dae-Gon; Khan, Wajiha; Merritt, Judith H; O'Toole, George A

2011-09-01

287

Contribution of bacterial cells to lacustrine organic matter based on amino sugars and D-amino acids  

E-print Network

23 April 2012 Abstract Amino sugars (ASs), D-amino acids (D-AAs), and bacterial cell counts were acids (AAs), neutral sugars, and amino sug- ars (ASs) (Cowie and Hedges, 1992; Benner and Kaiser, 2003Contribution of bacterial cells to lacustrine organic matter based on amino sugars and D-amino

Wehrli, Bernhard

288

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

PubMed

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. PMID:20331320

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

2010-03-21

289

Enzymatic tRNA acylation by acid and alpha-hydroxy acid analogues of amino acids.  

PubMed

Incorporation of unnatural amino acids with unique chemical functionalities has proven to be a valuable tool for expansion of the functional repertoire and properties of proteins as well as for structure-function analysis. Incorporation of alpha-hydroxy acids (primary amino group is substituted with hydroxyl) leads to the synthesis of proteins with peptide bonds being substituted by ester bonds. Practical application of this modification is limited by the necessity to prepare corresponding acylated tRNA by chemical synthesis. We investigated the possibility of enzymatic incorporation of alpha-hydroxy acid and acid analogues (lacking amino group) of amino acids into tRNA using aminoacyl-tRNA synthetases (aaRSs). We studied direct acylation of tRNAs by alpha-hydroxy acid and acid analogues of amino acids and corresponding chemically synthesized analogues of aminoacyl-adenylates. Using adenylate analogues we were able to enzymatically acylate tRNA with amino acid analogues which were otherwise completely inactive in direct aminoacylation reaction, thus bypassing the natural mechanisms ensuring the selectivity of tRNA aminoacylation. Our results are the first demonstration that the use of synthetic aminoacyl-adenylates as substrates in tRNA aminoacylation reaction may provide a way for incorporation of unnatural amino acids into tRNA, and consequently into proteins. PMID:18067322

Owczarek, Alina; Safro, Mark; Wolfson, Alexey D

2008-01-01

290

Amino Acids Regulate Transgene Expression in MDCK Cells  

PubMed Central

Gene expression and cell growth rely on the intracellular concentration of amino acids, which in metazoans depends on extracellular amino acid availability and transmembrane transport. To investigate the impact of extracellular amino acid concentrations on the expression of a concentrative amino acid transporter, we overexpressed the main kidney proximal tubule luminal neutral amino acid transporter B0AT1-collectrin (SLC6A19-TMEM27) in MDCK cell epithelia. Exogenously expressed proteins co-localized at the luminal membrane and mediated neutral amino acid uptake. However, the transgenes were lost over few cell culture passages. In contrast, the expression of a control transgene remained stable. To test whether this loss was due to inappropriately high amino acid uptake, freshly transduced MDCK cell lines were cultivated either with physiological amounts of amino acids or with the high concentration found in standard cell culture media. Expression of exogenous transporters was unaffected by physiological amino acid concentration in the media. Interestingly, mycoplasma infection resulted in a significant increase in transgene expression and correlated with the rapid metabolism of L-arginine. However, L-arginine metabolites were shown to play no role in transgene expression. In contrast, activation of the GCN2 pathway revealed by an increase in eIF2? phosphorylation may trigger transgene derepression. Taken together, high extracellular amino acid concentration provided by cell culture media appears to inhibit the constitutive expression of concentrative amino acid transporters whereas L-arginine depletion by mycoplasma induces the expression of transgenes possibly via stimulation of the GCN2 pathway. PMID:24797296

Torrente, Marta; Guetg, Adriano; Sass, Jörn Oliver; Arps, Lisa; Ruckstuhl, Lisa; Camargo, Simone M. R.; Verrey, François

2014-01-01

291

The amino acid composition of estuarine colloidal material  

NASA Astrophysics Data System (ADS)

Amino acids were determined in estuarine colloidal and particulate material from near surface waters ranging from fresh to brackish water (12 g kg -1 salinity). The hydrolizable amino acids and associated ammonia account for an average of 80% of the nitrogen present in colloidal samples, and approximately 75% of the nitrogen from particulate fractions of the same samples. The relative proportions of these amino acids are similar to those of a cultured estuarine diatom. There are no significant amounts of D amino acids, or non-protein amino acids characteristic of bacteria in sediments and soil. A single deep-water sample (25 m) shows some evidence of bottom mud resuspension by the presence of a possible aspartic acid-hydroxyproline dimer.

Sigleo, A. C.; Hare, P. E.; Helz, G. R.

1983-07-01

292

Metabolizable energy, nitrogen balance, and ileal digestibility of amino acids in quality protein maize for pigs  

PubMed Central

Background To compare the nutritional value and digestibility of five quality protein maize (QPM) hybrids to that of white and yellow maize, two experiments were carried out in growing pigs. In experiment 1, the energy metabolizability and the nitrogen balance of growing pigs fed one of five QPM hybrid diets were compared against those of pigs fed white or yellow maize. In experiment 2, the apparent and standardized ileal digestibility (AID and SID, respectively) of proteins and amino acids from the five QPM hybrids were compared against those obtained from pigs fed white and yellow maize. In both experiments, the comparisons were conducted using contrasts. Results The dry matter and nitrogen intakes were higher in the pigs fed the QPM hybrids (P?valine, phenylalanine, and methionine were lower in the QPM diets than those of maize (white and yellow) (all P?valine, phenylalanine, glutamic acid, serine, alanine, tyrosine, and proline (P?

2014-01-01

293

Orally supplemented l-arginine impairs amino acid absorption depending on dose in horses.  

PubMed

The beneficial effect of l-arginine (l-Arg) supplementation, on the physiology of several species, has generated an interest in the use of l-Arg as a nutraceutical in horses, but dosage and absorption of orally supplemented l-Arg must be inferred from other species. The study objective was to determine the effect of 2 oral l-Arg doses on plasma arginine concentrations and the effect on absorption of other amino acids in mares. In Experiment 1, mares were blocked by age and breed and were fed l-Arg supplemented (supplemented with 0.025% BW l-Arg; n = 6) or control (no supplement; n = 6) concentrate on a single day with blood samples taken at 0, 0.5, 1, 2, 3, 4, and 5 h relative to feeding. In Experiment 2, mares (n = 6) were used in a 3 × 3 Latin square design with l-Arg (0.0125% of BW), urea (0.0087% of BW), and control (no supplement) fed mixed into a grain concentrate as single meal with blood samples taken at 0, 1,2, 4, 6, 8,10, and 12 h relative to feeding. In Experiment 1, l-Arg supplementation increased (P < 0.05) plasma l-Arg and ornthine concentrations and decreased (P < 0.05) lysine and methionine concentrations compared with the control group. At 1 h post feeding, l-Arg mares had lower (P < 0.05) plasma concentrations of histidine, glutamic acid, proline, isoleucine, threonine, phenylalanine, leucine, valine, alanine, and taurine. In Experiment 2, l-Arg supplementation increased (P < 0.05) arginine and ornithine concentrations compared with urea and control; there was no difference among other amino acids. These experiments indicate that l-Argis absorbed and, dependent on the dose, alters the absorption of other amino acids in mares. PMID:25403187

Kelley, D E; Warren, L K; Mortensen, C J

2014-12-01

294

Polymerization of beta-amino acids in aqueous solution  

NASA Technical Reports Server (NTRS)

We have compared carbonyl diimidazole (CDI) and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC) as activating agents for the oligomerization of negatively-charged alpha- and beta-amino acids in homogeneous aqueous solution. alpha-Amino acids can be oligomerized efficiently using CDI, but not by EDAC. beta-Amino acids can be oligomerized efficiently using EDAC, but not by CDI. Aspartic acid, an alpha- and beta-dicarboxylic acid is oligomerized efficiently by both reagents. These results are explained in terms of the mechanisms of the reactions, and their relevance to prebiotic chemistry is discussed.

Liu, R.; Orgel, L. E.; Bada, J. L. (Principal Investigator)

1998-01-01

295

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

296

Amino Acids Availability of Poultry Feedstuffs in Pakistan  

Microsoft Academic Search

Quick bioassay technique of Sibbald (1986) involving adult cockerels was used to determine the amino acids availability of commonly used feedstuffs in Pakistan. Feedstuffs evaluated for amino acid availability were cereal grains (corn, rice, sorghum and wheat), cereal by-products (corn gluten feed, rice polishings and wheat bran), vegetable meals {corn gluten meal 30 and 60%, cottonseed meal expeller extracted (ee)

M. A. NADEEM; A. H. GILANI; A. G. KHAN

297

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

298

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

299

Vitreous Amino Acid Concentrations in Patients With Glaucoma Undergoing Vitrectomy  

Microsoft Academic Search

Objective: To measure vitreous concentrations of glu- tamate and other amino acids in patients with glaucoma undergoing vitrectomy. Methods: Undiluted vitreous samples were collected from patients undergoing vitrectomy at the University of Iowa (Iowa City) between 1997 and 1998 (n=69). Vitreous concentrations of 16 amino acids, including glutamate, were determined using high-pressure liquid chromatography. Patients with a history of diabetes

Robert A. Honkanen; Sankar Baruah; M. Bridget Zimmerman; Cheryl L. Khanna; Yaffa K. Weaver; Joanna Narkiewicz; Rafiq Waziri; Karen M. Gehrs; Thomas A. Weingeist; H. Culver Boldt; James C. Folk; Stephen R. Russell; Young H. Kwon; Hiroaki Isono; Shoji Kishi; Yasutaka Kimura; Naoya Hagiwara; Naoki Konishi; Hitoshi Fujii; Siavash Yazdanfar; Andrew M. Rollins; Joseph A. Izatt; Barbara Nemesure; Suh-Yuh Wu; Anselm Hennis; M. Cristina Leske

2003-01-01

300

Site specific incorporation of keto amino acids into proteins  

DOEpatents

Compositions and methods of producing components of protein biosynthetic machinery that include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, and orthogonal pairs of tRNAs/synthetases, which incorporate keto amino acids into proteins are provided. Methods for identifying these orthogonal pairs are also provided along with methods of producing proteins with keto amino acids using these orthogonal pairs.

Schultz, Peter G. (La Jolla, CA); Wang, Lei (San Diego, CA)

2011-03-22

301

Prediction of protein antigenic determinants from amino acid sequences  

Microsoft Academic Search

A method is presented for locating protein antigenic determinants by analyzing amino acid sequences in order to find the point of greatest local hydrophilicity. This is accomplished by assigning each amino acid a numerical value (hydrophilicity value) and then repetitively averaging these values along the peptide chain. The point of highest local average hydrophilicity is invariably located in, or immediately

T. P. Hopp; K. R. Woods

1981-01-01

302

Site specific incorporation of keto amino acids into proteins  

DOEpatents

Compositions and methods of producing components of protein biosynthetic machinery that include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, and orthogonal pairs of tRNAs/synthetases, which incorporate keto amino acids into proteins are provided. Methods for identifying these orthogonal pairs are also provided along with methods of producing proteins with keto amino acids using these orthogonal pairs.

Schultz, Peter G. (La Jolla, CA); Wang, Lei (San Diego, CA)

2008-10-07

303

Site specific incorporation of keto amino acids into proteins  

SciTech Connect

Compositions and methods of producing components of protein biosynthetic machinery that include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, and orthogonal pairs of tRNAs/synthetases, which incorporate keto amino acids into proteins are provided. Methods for identifying these orthogonal pairs are also provided along with methods of producing proteins with keto amino acids using these orthogonal pairs.

Schultz, Peter G. (La Jolla, CA); Wang, Lei (San Diego, CA)

2011-12-06

304

Amino Acid Difference Formula to Help Explain Protein Evolution  

Microsoft Academic Search

A formula for difference between amino acids combines properties that correlate best with protein residue substitution frequencies: composition, polarity, and molecular volume. Substitution frequencies agree much better with overall chemical difference between exchanging residues than with minimum base changes between their codons. Correlation coefficients show that fixation of mutations between dissimilar amino acids is generally rare.

R. Grantham

1974-01-01

305

Site specific incorporation of keto amino acids into proteins  

SciTech Connect

Compositions and methods of producing components of protein biosynthetic machinery that include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, and orthogonal pairs of tRNAs/synthetases, which incorporate keto amino acids into proteins are provided. Methods for identifying these orthogonal pairs are also provided along with methods of producing proteins with keto amino acids using these orthogonal pairs.

Schultz, Peter G. (La Jolla, CA); Wang, Lei (San Diego, CA)

2009-04-28

306

Production of amino acids using auxotrophic mutants of methylotrophic bacillus  

DOEpatents

A method of producing amino acids by culturing an amino acid auxotroph of a biologically pure strain of a type I methylotrophic bacterium of the genus Bacillus which exhibits sustained growth at 50.degree. C. using methanol as a carbon and energy source and requiring vitamin B.sub.12 and biotin is provided.

Hanson, Richard S. (Wayzata, MN); Flickinger, Michael C. (St. Paul, MN); Schendel, Frederick J. (Falcon Heights, MN); Guettler, Michael V. (Waconia, MN)

2001-07-17

307

Site specific incorporation of keto amino acids into proteins  

SciTech Connect

Compositions and methods of producing components of protein biosynthetic machinery that include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, and orthogonal pairs of tRNAs/synthetases, which incorporate keto amino acids into proteins are provided. Methods for identifying these orthogonal pairs are also provided along with methods of producing proteins with keto amino acids using these orthogonal pairs.

Schultz, Peter G. (La Jolla, CA); Wang, Lei (San Diego, CA)

2012-02-14

308

Interactive Hangman Teaches Amino Acid Structures and Abbreviations  

ERIC Educational Resources Information Center

We developed an interactive exercise to teach students how to draw the structures of the 20 standard amino acids and to identify the one-letter abbreviations by modifying the familiar game of "Hangman." Amino acid structures were used to represent single letters throughout the game. To provide additional practice in identifying…

Pennington, Britney O.; Sears, Duane; Clegg, Dennis O.

2014-01-01

309

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...

310

Rapid and Precise Determination of Cellular Amino Acid Flux Rates  

E-print Network

Rapid and Precise Determination of Cellular Amino Acid Flux Rates Using HPLC with Automated in complete cell media using an Agilent 1100 HPLC with a ZORBAX Eclipse Plus C18 column with absorbance synthesis may consume larger quantities of amino acids than other cell types. HPLC with precolumn

Wikswo, John

311

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...

312

Targets of Amino Acid Restriction in Prostate Cancer  

Cancer.gov

The objective of this application is to identify the molecular target(s) by which specific amino acid dependency modulates the viability and invasiveness of human androgen-independent prostate cancer calls. We hypothesize that specific amino acid-regulated invasion is dependent on the inhibition of FAK and its binding partners.

313

INTESTINAL SULFUR AMINO ACID METABOLISM IN NEONATAL PIGLETS  

Technology Transfer Automated Retrieval System (TEKTRAN)

BACKGROUND: Methionine (Met) is an essential sulfur amino acid that functions as a key precursor for the synthesis of homocysteine and cysteine, via transmethylation (TM) and transsulfuration (TS), respectively. Cysteine is a semi-essential amino acid in neonates.We previously showed that significan...

314

Amino acids control ammonia pulses in yeast colonies  

Microsoft Academic Search

Individual yeast colonies produce pulses of volatile ammonia separated by phases of medium acidification. Colonies of Saccharomyces cerevisiae mutant defective in the general amino acid permease, Gap1p, exhibit decreased ammonia production. Mutations in the S. cerevisiae amino acid sensor SPS completely abolish the colony ammonia pulses. In contrast, the ammonia pulse production is independent of external concentrations of ammonium and

Blanka Zikánová; Martin Kuthan; Markéta ?i?icová; Jitka Forstová; Zdena Palková

2002-01-01

315

Amino Acid Diets and Maximal Growth in the Rat  

Microsoft Academic Search

Amino acid diets fed in an agar gel have been found to support weight gains of rats as great or greater than those obtained with diets containing an equiva lent quantity of casein supplemented with methionine. Over 1% arginine, 0.6% asparagine and feeding the diet in gel form were necessary to obtain maximal weight gain. The diet contained amino acids

Q. R. ROGERS ANDA; E. HARPER

316

Abnormalities of cerebrospinal fluid amino-acids in purulent meningitis  

PubMed Central

Serial measurements were made of the cerebrospinal fluid and plasma amino-acid concentrations in 12 patients with purulent meningitis. Marked increases in the concentrations of most CSF amino-acids were found, possibly caused by altered transport mechanisms in the inflamed meninges and choroid plexuses. PMID:512663

Corston, R. N.; McGale, E. H. F.; Stonier, C.; Hutchinson, E. C.; Aber, G. M.

1979-01-01

317

Kinetics of amino acid and glucose absorption following pancreatic diversion in the pig  

NASA Technical Reports Server (NTRS)

An experiment was conducted in the pig to determine the consequences of deprivation of exocrine pancreatic secretion on the composition and quantity of nutrients absorbed after intake of a balanced diet. Five growing pigs (53.8 kg body weight) were fitted with permanent catheters in the portal vein and the carotid artery and with an electromagnetic flow probe around the portal vein to measure the exchanges between the blood and the intestinal lumen. They were also fitted with a permanent catheter in the duct of Wirsung to educe the exocrine pancreatic secretion and another one in the duodenum in order to reintroduce it. In each animal, glucose, amino-N and amino acid absorption as well as insulin and glucagon production were measured over a period of 10 h after the meal (semi-purified diet based on purified starch and containing 180 g fish meal/kg, DM content of the meal 731 g), either in the presence of pancreatic juice (group C: immediate reintroduction), or in the absence of pancreatic juice (group D: deprivation). The deprivation of pancreatic juice provoked a marked depression in the absorption of glucose (D 67.9 (SEM 27.9) g/10 h, C 437.7 (SEM 39.5) g/10 h, P < 0.001), and of amino-N (D 7.55 (SEM 0.54) g/10 h, C 15.80 (SEM 0.79) g/10 h, P < 0.001). The composition of the mixture of amino acids in the portal blood was only slightly modified: only the levels of histidine (P < 0.05) and of valine (P < 0.06, NS) decreased in the absence of pancreatic juice. Insulin production was much lower (by 64%, P < 0.05) in the absence of pancreatic juice whereas that of glucagon was not affected.

Rerat, A.; Calmes, R.; Corring, T.; Vaissade, P.

1996-01-01

318

Urinary Amino Acid Analysis: A Comparison of iTRAQ®-LC-MS/MS, GC-MS, and Amino Acid Analyzer  

PubMed Central

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.

2009-01-01

319

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

2009-07-01

320

Role of sialic acid in synaptosomal transport of amino acid transmitters  

SciTech Connect

Active, high-affinity, sodium-dependent uptake of (/sup 14/C)-aminobutyric acid and of the acidic amino acid D-(/sup 3/H)-aspartate was inhibited by pretreatment of synaptosomes with neuraminidase from Vibrio cholerae. Inhibition was of a noncompetitive type and was related to the amount of sialic acid released. The maximum accumulation ratios of both amino acids (intracellular (amino acid)/extracellular (amino acid)) remained largely unaltered. Treatment with neuraminidase affected neither the synaptosomal energy levels nor the concentration of internal potassium. It is suggested that the ..gamma..-aminobutyric acid and acidic amino acid transporters are glycosylated and that sialic acid is involved in the operation of the carrier proteins directly and not through modification of driving forces responsible for amino acid uptake.

Zaleska, M.M.; Erecinska, M.

1987-03-01

321

Interaction of metal ions and amino acids - Possible mechanisms for the adsorption of amino acids on homoionic smectite clays  

NASA Technical Reports Server (NTRS)

A semiempirical molecular orbital method is used to characterize the binding of amino acids to hexahydrated Cu(2+) and Ni(2+), a process presumed to occur when they are adsorbed in the interlamellar space of homoionic smectite clays. Five alpha-amino acids, beta-alanine, and gamma-aminobutyric acid were used to investigate the metal ion and amino acid specificity in binding. It was assumed that the alpha, beta, and gamma-amino acids would bind as bidentate anionic ligands, forming either 1:1 or 1:2 six-coordinated five, six, and seven-membered-ring chelate complexes, respectively. Energies of complex formation, optimized geometries, and electron and spin distribution were determined; and steric constraints of binding of the amino acids to the ion-exchanged cations in the interlamellar spacing of a clay were examined. Results indicate that hexahydrated Cu(2+) forms more stable complexes than hexahydrated Ni(2+) with all the amino acids studied. However, among these amino acids, complex formation does not favor the adsorption of the biological subset. Calculated energetics of complex formation and steric constraints are shown to predict that 1:1 rather than 1:2 metal-amino acid complexes are generally favored in the clay.

Gupta, A.; Loew, G. H.; Lawless, J.

1983-01-01

322

Supernovae, Neutrinos and the Chirality of Amino Acids  

PubMed Central

A mechanism for creating an enantioenrichment in the amino acids, the building blocks of the proteins, that involves global selection of one handedness by interactions between the amino acids and neutrinos from core-collapse supernovae is defined. The chiral selection involves the dependence of the interaction cross sections on the orientations of the spins of the neutrinos and the 14N nuclei in the amino acids, or in precursor molecules, which in turn couple to the molecular chirality. It also requires an asymmetric distribution of neutrinos emitted from the supernova. The subsequent chemical evolution and galactic mixing would ultimately populate the Galaxy with the selected species. The resulting amino acids could either be the source thereof on Earth, or could have triggered the chirality that was ultimately achieved for Earth’s proteinaceous amino acids. PMID:21747686

Boyd, Richard N.; Kajino, Toshitaka; Onaka, Takashi

2011-01-01

323

Supernovae, neutrinos and the chirality of amino acids.  

PubMed

A mechanism for creating an enantioenrichment in the amino acids, the building blocks of the proteins, that involves global selection of one handedness by interactions between the amino acids and neutrinos from core-collapse supernovae is defined. The chiral selection involves the dependence of the interaction cross sections on the orientations of the spins of the neutrinos and the (14)N nuclei in the amino acids, or in precursor molecules, which in turn couple to the molecular chirality. It also requires an asymmetric distribution of neutrinos emitted from the supernova. The subsequent chemical evolution and galactic mixing would ultimately populate the Galaxy with the selected species. The resulting amino acids could either be the source thereof on Earth, or could have triggered the chirality that was ultimately achieved for Earth's proteinaceous amino acids. PMID:21747686

Boyd, Richard N; Kajino, Toshitaka; Onaka, Takashi

2011-01-01

324

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. PMID:23417007

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

2013-01-01

325

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

326

Insulin resistance and regulation of serum amino acid levels in myotonic dystrophy.  

PubMed

To quantify the degree of whole body insulin resistance in patients with myotonic dystrophy and to determine if these same patients display signs of a whole body decrease in the action of insulin on amino acid uptake and glucose disposal, three separate 120 min studies employing the euglycaemic insulin clamp technique (20, 80 and 200 m-units min-1 m-2) were performed on five ambulatory patients with myotonic dystrophy. The results were compared with findings obtained in identical studies in 21 normal volunteers. Myotonic dystrophy patients showed a slower, less marked decline in the serum concentration of insulin sensitive amino acids (threonine, valine, leucine, isoleucine, tyrosine, phenylalanine) during all three insulin infusions compared with normals. The greatest difference occurred at the low physiological elevations of insulin produced by the 20 m-units min-1 m-2 infusion. Alanine levels fell significantly below baseline in patients with myotonic dystrophy after 60 and 120 min of insulin infusion with all three rates of insulin infusion. Normal subjects had only a minimal, insignificant decline in arterialized alanine concentrations during the three different insulin infusions. Creatinine adjusted rates of whole body glucose disposal were 30-40% lower in the myotonic dystrophy group at all three doses of insulin compared with the normals. This demonstrates that their insulin resistance was not due simply to a reduction in muscle mass. The overall pattern of findings in these studies of patients with myotonic dystrophy indicates that there is a whole body derangement in the regulation of circulating amino acid levels by insulin as well as a marked decrease in the action of this hormone in stimulating glucose uptake by target tissues. PMID:3530612

Moxley, R T; Kingston, W J; Minaker, K L; Corbett, A J; Rowe, J W

1986-10-01

327

High resolution mass analysis of N- and C-terminal negative ions resulting from resonance electron capture by aliphatic amino acids.  

PubMed

High mass resolving power was applied to study resonance electron capture by glycine, alanine, and valine, and accurate mass measurements helped to distinguish between some negative ions having the same nominal masses. It was established that the C- and N-terminal negative ions of the same nominal masses were formed at different electron energies from different resonance states. The typical fragmentation pathways in deprotonated amino acids via loss of water initiated by collisional activation were not observed upon resonant electron capture by aliphatic amino acids. Instead, [M-18](-) negative ions in the vicinity of 5 eV were found to be associated with simultaneous loss of either ammonia and a hydrogen atom or an amino group and a hydrogen molecule. PMID:20572704

Shchukin, Pavel V; Muftakhov, Mars V; Morré, Jeff; Deinzer, Max L; Vasil'ev, Yury V

2010-06-21

328

How Do Haloarchaea Synthesize Aromatic Amino Acids?  

PubMed Central

Genomic analysis of H. salinarum indicated that the de novo pathway for aromatic amino acid (AroAA) biosynthesis does not follow the classical pathway but begins from non-classical precursors, as is the case for M. jannaschii. The first two steps in the pathway were predicted to be carried out by genes OE1472F and OE1475F, while the 3rd step follows the canonical pathway involving gene OE1477R. The functions of these genes and their products were tested by biochemical and genetic methods. In this study, we provide evidence that supports the role of proteins OE1472F and OE1475F catalyzing consecutive enzymatic reactions leading to the production of 3-dehydroquinate (DHQ), after which AroAA production proceeds via the canonical pathway starting with the formation of DHS (dehydroshikimate), catalyzed by the product of ORF OE1477R. Nutritional requirements and AroAA uptake studies of the mutants gave results that were consistent with the proposed roles of these ORFs in AroAA biosynthesis. DNA microarray data indicated that the 13 genes of the canonical pathway appear to be utilised for AroAA biosynthesis in H. salinarum, as they are differentially expressed when cells are grown in medium lacking AroAA. PMID:25216252

Gulko, Miriam Kolog; Dyall-Smith, Mike; Gonzalez, Orland; Oesterhelt, Dieter

2014-01-01

329

Anatomical and pharmacological characterization of excitatory amino acid receptors  

SciTech Connect

The majority of the excitatory neurotransmission in the vertebrate Central Nervous System is thought to be mediated by acidic amino acid neurotransmitters. However, relatively little is known about the excitatory amino acid receptors and their distribution within the CNS. By analyzing radioligand binding to purified synaptic plasma membranes and to thin tissue sections processed for autoradiography, multiple distinct binding sites were found. These binding sites exhibited the pharmacological properties indicative of the excitatory amino acid receptors, which had been identified by electrophysiological techniques. Specifically, L-(/sup 3/H)-glutamate and D-(/sup 3/H)-amino-5-phosphonopentanoate appear to label N-methyl-D-aspartate receptors, L-(/sup 3/H)-glutamate and (/sup 3/H)-kainic acid appear to label kainic acid receptors, and L-(/sup 3/H)-glutamate and (/sup 3/H)-amino-3-hydroxy-5-methyl-4-isoxazolepropionate appear to label quisqualate receptors. Together, these results confirm the three receptor scheme proposed for excitatory amino acid neurotransmission. These results also show that these transmitter-receptor systems are differentially distributed in the brain, and that the total distribution is consistent with that found by other markers for excitatory amino acid-using neurons.

Monaghan, D.T.

1985-01-01

330

Developmental Changes in the Free Amino Acid Pool and Total Protein Amino Acids of Pea Cotyledons (Pisum sativum L.)  

PubMed Central

Changes in the levels of twenty-two free amino acids and in the amino acid composition of the total protein were measured throughout the development of cotyledons of a dwarf garden pea, Pisum sativum cv Greenfeast, grown in a constant environment. A sensitive double-isotope dansylation technique was used. Fresh weight, dry weight, and protein content were also followed. Twenty of the amino acids showed synchronous changes in levels, giving a developmental pattern containing four peaks; major peaks occurred very early and very late in development. The amino acid composition of the total protein, which was always very different from that of the free amino acid pool, showed early changes to one consistent with the final storage protein composition of the seed. These changes included a 50% drop in methionine content and a 70% rise in cysteine. While the maximum free methionine level occurred early in development, that of cysteine was late. PMID:16663030

Macnicol, Peter K.

1983-01-01

331

Chemical interaction between titanium implant surface and amino acids.  

PubMed

The purpose of this study was to investigate the chemical interaction between titanium implant surface and amino acids. Pure titanium disks were pretreated with 10 N HCl and ultrapure water at room temperature for 30 minutes each. Disks were then modified with one of the three amino acids--L-aspartic acid, L-serine, or L-threonine--at 37 degrees C for 12 hours. Modification with oxalic acid was used as a control. By means of X-ray photoelectron spectroscopy (XPS), amino acid powders and the modified surfaces without or with ultrasonic water rinsing were chemically analyzed. It was revealed that the N 1s peak which originated from amino acids was not or hardly detected in the wide scan spectra of amino acid-modified surfaces. Moreover, the COO- peak which originated from oxalic acid could hardly be detected in the narrow scan spectrum of the C is region of oxalic acid-modified surface with ultrasonic water rinsing. Based on the results of this study, it was concluded that amino acids could not chemically bond to the titanium surface. PMID:17621929

Hiasa, Kyou; Abe, Yasuhiko; Yoshida, Yasuhiro; Taji, Tsuyoshi; Suzuki, Kazuomi; Akagawa, Yasumasa

2007-03-01

332

Purification, characterization, and complete amino acid sequence of a trypsin inhibitor from amaranth (Amaranthus hypochondriacus) seeds.  

PubMed Central

A protein proteinase inhibitor was purified from a seed extract of amaranth (Amaranthus hypochondriacus) by precipitation with (NH4)2SO4, gel-filtration chromatography, ion-exchange chromatography, and reverse-phase high-performance liquid chromatography. It is a 69-amino acid protein with a high content of valine, arginine, and glutamic acid, but lacking in methionine. The inhibitor has a relative molecular weight of 7400 and an isoelectric point of 7.5. It is a serine proteinase inhibitor that recognizes chymotrypsin, trypsin, and trypsin-like proteinase activities extracted from larvae of the insect Prostephanus truncatus. This inhibitor belongs to the potato-I inhibitor family, showing the closest homology (59.5%) with the Lycopersicum peruvianum trypsin inhibitor, and (51%) with the proteinase inhibitor 5 extracted from the seeds of Cucurbita maxima. The position of the lysine-aspartic acid residues present in the active site of the amaranth inhibitor are found in almost the same relative position as in the inhibitor from C. maxima. PMID:8290633

Valdes-Rodriguez, S; Segura-Nieto, M; Chagolla-Lopez, A; Verver y Vargas-Cortina, A; Martinez-Gallardo, N; Blanco-Labra, A

1993-01-01

333

Negative effect of heat sterilization on the free amino acid concentrations in infant formula.  

PubMed

Infant formulas are often heat sterilized in hospitals where water contamination or nosocomial infection is a concern, but there are few studies of the effect of high heat on the nutritional value of infant formula. In particular, the effect of heat sterilization on free amino acid (FAA) concentrations is seldom discussed. In view of the importance of these nutrients for infant growth, we investigated the FAA concentrations of infant formula after heat sterilization. Powdered infant formulas were reconstituted with hot water (80 degrees C) in glass bottles and placed in an autoclave for 5 min at 105 degrees C and 5600 kg/m2 of pressure. Additional samples of formula were prepared by conventional methods to serve as controls. After autoclaving, we measured the FAA concentrations with ion exchange chromatography. The results were compared with those obtained after conventional preparation. We found a 19.5% lower amount of total protein after autoclaving compared with conventional preparation. Concentrations of total FAA were significantly lower after autoclaving (696.5 +/- 101.4 vs 899.4 +/- 152.2 micromol/l, P = 0.01). The concentrations of individual amino acids were also lower in autoclaved infant formulas, with differences ranging from -4.1 to 71.5% (mean 22.6%). Concentrations of certain amino acids were more than 30% lower, such as valine (71.5%), citrulline (61.1%), glutamine (60.6%), ethanolamine (54%), and lysine (39.2%). Both essential and nonessential amino acids were similarly affected by autoclaving, 28.17 and 27.13%, respectively, lower than in controls (P = 0.37). The concentration of ammonia was significantly higher after autoclaving (645.2 +/- 76.2 vs 393.2 +/-140.7 micromol/l, P = 0.0003). However, the urea level was significantly lower after autoclaving than after conventional preparation (1110.8 +/- 162.7 vs 1426.5 +/- 209.5 micromol/l, P = 0.0004). The accumulation of ammonia may reflect degradation of protein and amino acids. Autoclaving clearly results in decreased concentrations of FAA in infant formula. The increased concentration of ammonia after autoclaving is of concern if it leads to deleterious effects. PMID:16234843

Yeung, C Y; Lee, H C; Lin, S P; Yang, Y C; Huang, F Y; Chuang, C K

2006-01-01

334

Plasma and Urinary Amino Acid Metabolomic Profiling in Patients with Different Levels of Kidney Function  

PubMed Central

Summary Background and objectives Patients with CKD display altered plasma amino acid profiles. This study estimated the association between the estimated GFR and urinary and plasma amino acid profiles in CKD patients. Design, setting, participants, & measurements Urine and plasma samples were taken from 52 patients with different stages of CKD, and plasma samples only were taken from 25 patients on maintenance hemodialysis. Metabolic profiling was performed by liquid chromatography coupled with tandem mass spectrometry after phenylisothiocyanate derivatization. Results Most plasma amino acid concentrations were decreased in hemodialysis patients, whereas proline, citrulline, asparagine, asymmetric dimethylarginine, and hydroxykynurenine levels were increased (P<0.05). Both plasma levels and urinary excretion of citrulline were higher in the group of patients with advanced CKD (CKD stages 2 and 3 versus CKD stages 4 and 5; in plasma: 35.9±16.3 versus 61.8±23.6 µmol/L, P<0.01; in urine: 1.0±1.2 versus 7.1±14.3 µmol/mol creatinine, P<0.001). Plasma asymmetric dimethylarginine levels were higher in advanced CKD (CKD stages 2 and 3, 0.57±0.29; CKD stages 4 and 5, 1.02±0.48, P<0.001), whereas urinary excretion was lower (2.37±0.93 versus 1.51±1.43, P<0.001). Multivariate analyses adjusting on estimated GFR, serum albumin, proteinuria, and other covariates revealed associations between diabetes and plasma citrulline (P=0.02) and between serum sodium and plasma asymmetric dimethylarginine (P=0.03). Plasma tyrosine to phenylalanine and valine to glycine ratios were lower in advanced CKD stages (P<0.01). Conclusion CKD patients have altered plasma and urinary amino acid profiles that are not corrected by dialysis. Depending on solutes, elevated plasma levels were associated with increased or decreased urinary excretion, depicting situations of uremic retention (asymmetric dimethylarginine) or systemic overproduction (citrulline). These results give some insight in the CKD-associated modifications of amino acid metabolism, which may help improve their handling. PMID:24235289

Duranton, Flore; Lundin, Ulrika; Gayrard, Nathalie; Mischak, Harald; Aparicio, Michel; Mourad, Georges; Daurès, Jean-Pierre; Weinberger, Klaus M.

2014-01-01

335

The requirements of the brain for some amino acids.  

PubMed Central

1. A constant specific activity of radioactively labelled amino acids was maintained in the circulation by means of a new technique devised for this purpose. This has made it possible to measure accurately the entry rates of amino acids into the brain in vivo. 2. The rates of entry into the brain of seven nutritionally non-essential amino acids were measured. 3. Glycine and proline enter the brain relatively slowly, at rates comparable to those of amino acids which are not normally found in the blood. Thus their entry is due mainly if not entirely to passive diffusion. 4. Serine (which is used by the brain to make glycine) and alanine (which is used to make glutamate and aspartate) enter the brain as rapidly as the essential amino acids and thus, although not essential for the body as a whole, appear to be essential for the brain. 5. It is suggested that those amino acids that the brain is able to synthesize have low rates of entry, even though they are present at high concentrations in the plasma, but that the transport systems for those amino acids that are not synthesized in the brain ensure rapid entry at rates that are related to the rates of cerebral utilization. PMID:1133786

Baños, G; Daniel, P M; Moorhouse, S R; Pratt, O E

1975-01-01

336

Protein, amino acids and the control of food intake.  

PubMed

The influence of protein and amino acid on the control of food intake and the specific control of protein and amino acid intakes remains incompletely understood. The most commonly accepted conclusions are: (1) the existence of an aversive response to diets deficient in or devoid of protein or deficient in at least one essential amino acid; (2) the existence of a mechanism that enables attainment of the minimum requirement for N and essential amino acids by increasing intake of a low-protein diet; (3) a decrease in the intake of a high-protein diet is associated with different processes, including the high satiating effect of protein. Ingested proteins are believed to generate pre- and post-absorptive signals that contribute to the control of gastric kinetics, pancreatic secretion and food intake. At the brain level, two major afferent pathways are involved in protein and amino acid monitoring: the indirect neuro-mediated (mainly vagus-mediated) pathway and the direct blood pathway. The neuro-mediated pathway transfers pre-absorptive and visceral information. This information is for the main part transferred through the vagus nerve that innervates part of the oro-sensory zone: the stomach, the duodenum and the liver. Other information is directly monitored in the blood. It is likely that the system responds precisely when protein and essential amino acid intake is inadequate, but in contrast allows a large range of adaptive capacities through amino acid degradation and substrate interconversion. PMID:15384319

Tome, Daniel

2004-08-01

337

Mating frequency influences nectar amino acid preference of Pieris napi.  

PubMed Central

It is generally assumed that butterflies, as is the case with many holometabolous insects, rely primarily on nutrients gathered by larval feeding for somatic maintenance and fecundity. These reserves can be supplemented by adult feeding and in some cases by nuptial gifts passed from the males to the females during mating. Recent findings indicate that female butterflies detect and prefer nectar with high levels of amino acids, thus calling new attention to this nutritive source. Polyandrous species can further supplement their larval stores with additional nuptial gifts. This study examined how mating frequency of the polyandrous butterfly Pieris napi affects the female's preference for nectar amino acids. Females of this species generally detect and prefer nectar mimics containing amino acids. However, nectar amino acid preference is significantly lower in mated females. Furthermore, nectar amino acid preference increases when females are not allowed to remate, whereas the preference of twice-mated females remains constant at a lower level. These results indicate a versatile response of females to nectar amino acids, depending on their nutritional status; they may even switch their source of amino acids between adult feeding and nuptial gifts. PMID:15058391

Mevi-Schütz, Jovanne; Erhardt, Andreas

2004-01-01

338

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

Microsoft Academic Search

Stable carbon isotope ratios (? 13C) were determined for alanine, proline, phenylalanine, valine, leucine, isoleucine, aspartate (aspartic acid and asparagine), glutamate (glutamic acid and glu- tamine), 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

JAMES H. SCOTT; DIANE M. O'BRIEN; DAVID EMERSON; HENRY SUN; GENE D. McDONALD; ANTONIO SALGADO; MARILYN L. FOGEL

339

Synthesis and chirality of amino acids under interstellar conditions.  

PubMed

Amino acids are the fundamental building blocks of proteins, the biomolecules that provide cellular structure and function in all living organisms. A majority of amino acids utilized within living systems possess pre-specified orientation geometry (chirality); however the original source for this specific orientation remains uncertain. In order to trace the chemical evolution of life, an appreciation of the synthetic and evolutional origins of the first chiral amino acids must first be gained. Given that the amino acids in our universe are likely to have been synthesized in molecular clouds in interstellar space, it is necessary to understand where and how the first synthesis might have occurred. The asymmetry of the original amino acid synthesis was probably the result of exposure to chiral photons in the form of circularly polarized light (CPL), which has been detected in interstellar molecular clouds. This chirality transfer event, from photons to amino acids, has been successfully recreated experimentally and is likely a combination of both asymmetric synthesis and enantioselective photolysis. A series of innovative studies have reported successful simulation of these environments and afforded production of chiral amino acids under realistic circumstellar and interstellar conditions: irradiation of interstellar ice analogues (CO, CO2, NH3, CH3OH, and H2O) with circularly polarized ultraviolet photons at low temperatures does result in enantiomer enriched amino acid structures (up to 1.3% ee). This topical review summarizes current knowledge and recent discoveries about the simulated interstellar environments within which amino acids were probably formed. A synopsis of the COSAC experiment onboard the ESA cometary mission ROSETTA concludes this review: the ROSETTA mission will soft-land on the nucleus of the comet 67P/Churyumov-Gerasimenko in November 2014, anticipating the first in situ detection of asymmetric organic molecules in cometary ices. PMID:22976459

Giri, Chaitanya; Goesmann, Fred; Meinert, Cornelia; Evans, Amanda C; Meierhenrich, Uwe J

2013-01-01

340

40 CFR 721.10633 - Aromatic sulfonic acid amino azo dye salts (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Aromatic sulfonic acid amino azo dye salts (generic). 721...721.10633 Aromatic sulfonic acid amino azo dye salts (generic). ...identified generically as aromatic sulfonic acid amino azo dye salts (PMN...

2013-07-01

341

40 CFR 721.430 - Oxo-substituted amino-al-kanoic acid derivative.  

Code of Federal Regulations, 2012 CFR

... false Oxo-substituted amino-al-kanoic acid derivative. 721.430...430 Oxo-substituted amino-al-kanoic acid derivative. (a) Chemical...generically as oxo-substituted amino al-kan-oic acid derivative (PMN No....

2012-07-01

342

40 CFR 721.10474 - Substituted amino ethane sulfonic acid salt (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Substituted amino ethane sulfonic acid salt (generic). 721...721.10474 Substituted amino ethane sulfonic acid salt (generic). ...generically as substituted amino ethane sulfonic acid salt (PMN...

2013-07-01

343

40 CFR 721.10630 - Amino acid, carboxyalkyl, alkylsulfonate, alkali salt (generic).  

...2014-07-01 2014-07-01 false Amino acid, carboxyalkyl, alkylsulfonate...Chemical Substances § 721.10630 Amino acid, carboxyalkyl, alkylsulfonate...substances identified generically as amino acid, carboxyalkyl,...

2014-07-01

344

37 CFR 1.821 - Nucleotide and/or amino acid sequence disclosures in patent applications.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Nucleotide and/or amino acid sequence disclosures in patent applications...Disclosures Containing Nucleotide And/or Amino Acid Sequences § 1.821 Nucleotide and/or amino acid sequence disclosures in patent...

2010-07-01

345

40 CFR 721.10380 - Benzoic acid, 3-amino-2-mercapto-.  

...2014-07-01 false Benzoic acid, 3-amino-2-mercapto-. 721.10380...Substances § 721.10380 Benzoic acid, 3-amino-2-mercapto-. (a) Chemical...substance identified as benzoic acid, 3-amino-2-mercapto- (PMN...

2014-07-01

346

40 CFR 721.1728 - Benzoic acid, 2-(3-phenylbutylidene)amino-, methyl ester.  

Code of Federal Regulations, 2010 CFR

... false Benzoic acid, 2-(3-phenylbutylidene)amino-, methyl ester...721.1728 Benzoic acid, 2-(3-phenylbutylidene)amino-, methyl ester...identified as benzoic acid, 2-(3-phenylbutylidene)amino-, methyl...

2010-07-01

347

40 CFR 721.1728 - Benzoic acid, 2-(3-phenylbutylidene)amino-, methyl ester.  

Code of Federal Regulations, 2013 CFR

... false Benzoic acid, 2-(3-phenylbutylidene)amino-, methyl ester...721.1728 Benzoic acid, 2-(3-phenylbutylidene)amino-, methyl ester...identified as benzoic acid, 2-(3-phenylbutylidene)amino-, methyl...

2013-07-01

348

40 CFR 721.1728 - Benzoic acid, 2-(3-phenylbutylidene)amino-, methyl ester.  

Code of Federal Regulations, 2012 CFR

... false Benzoic acid, 2-(3-phenylbutylidene)amino-, methyl ester...721.1728 Benzoic acid, 2-(3-phenylbutylidene)amino-, methyl ester...identified as benzoic acid, 2-(3-phenylbutylidene)amino-, methyl...

2012-07-01

349

37 CFR 1.821 - Nucleotide and/or amino acid sequence disclosures in patent applications.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Nucleotide and/or amino acid sequence disclosures in patent applications...Disclosures Containing Nucleotide And/or Amino Acid Sequences § 1.821 Nucleotide and/or amino acid sequence disclosures in patent...

2013-07-01

350

40 CFR 721.1728 - Benzoic acid, 2-(3-phenylbutylidene)amino-, methyl ester.  

Code of Federal Regulations, 2011 CFR

... false Benzoic acid, 2-(3-phenylbutylidene)amino-, methyl ester...721.1728 Benzoic acid, 2-(3-phenylbutylidene)amino-, methyl ester...identified as benzoic acid, 2-(3-phenylbutylidene)amino-, methyl...

2011-07-01

351

40 CFR 721.10380 - Benzoic acid, 3-amino-2-mercapto-.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Benzoic acid, 3-amino-2-mercapto-. 721.10380...Substances § 721.10380 Benzoic acid, 3-amino-2-mercapto-. (a) Chemical...substance identified as benzoic acid, 3-amino-2-mercapto- (PMN...

2012-07-01

352

Accuracies of Ancestral Amino Acid Sequences Inferred by the Parsimony, Likelihood, and Distance Methods  

E-print Network

Accuracies of Ancestral Amino Acid Sequences Inferred by the Parsimony, Likelihood, and Distance- cestral organisms is important for identifying critical amino acid substitutions that have caused amino acids inferred by two currently available methods (maximum- parsimony [MP] and maximum

Zhang, Jianzhi

353

4 Aromatic Amino Acids in the Brain M. Cansev . R. J. Wurtman  

E-print Network

4 Aromatic Amino Acids in the Brain M. Cansev . R. J. Wurtman 1 Introduction ..................................................................................... 60 2 Sources of Aromatic Amino Acids .............................................................. 61 3 Plasma Concentrations of the Aromatic Amino Acids ......................................... 62 3

Wurtman, Richard

354

37 CFR 1.821 - Nucleotide and/or amino acid sequence disclosures in patent applications.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Nucleotide and/or amino acid sequence disclosures in patent applications...Disclosures Containing Nucleotide And/or Amino Acid Sequences § 1.821 Nucleotide and/or amino acid sequence disclosures in patent...

2012-07-01

355

40 CFR 721.430 - Oxo-substituted amino-al-kanoic acid derivative.  

Code of Federal Regulations, 2011 CFR

... false Oxo-substituted amino-al-kanoic acid derivative. 721.430...430 Oxo-substituted amino-al-kanoic acid derivative. (a) Chemical...generically as oxo-substituted amino al-kan-oic acid derivative (PMN No....

2011-07-01

356

40 CFR 721.430 - Oxo-substituted amino-al-kanoic acid derivative.  

Code of Federal Regulations, 2010 CFR

... false Oxo-substituted amino-al-kanoic acid derivative. 721.430...430 Oxo-substituted amino-al-kanoic acid derivative. (a) Chemical...generically as oxo-substituted amino al-kan-oic acid derivative (PMN No....

2010-07-01

357

40 CFR 721.1728 - Benzoic acid, 2-(3-phenylbutylidene)amino-, methyl ester.  

... false Benzoic acid, 2-(3-phenylbutylidene)amino-, methyl ester...721.1728 Benzoic acid, 2-(3-phenylbutylidene)amino-, methyl ester...identified as benzoic acid, 2-(3-phenylbutylidene)amino-, methyl...

2014-07-01

358

37 CFR 1.821 - Nucleotide and/or amino acid sequence disclosures in patent applications.  

...2014-07-01 false Nucleotide and/or amino acid sequence disclosures in patent applications...Disclosures Containing Nucleotide And/or Amino Acid Sequences § 1.821 Nucleotide and/or amino acid sequence disclosures in patent...

2014-07-01

359

40 CFR 721.10474 - Substituted amino ethane sulfonic acid salt (generic).  

...2014-07-01 false Substituted amino ethane sulfonic acid salt (generic). 721...721.10474 Substituted amino ethane sulfonic acid salt (generic). ...generically as substituted amino ethane sulfonic acid salt (PMN...

2014-07-01

360

37 CFR 1.821 - Nucleotide and/or amino acid sequence disclosures in patent applications.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Nucleotide and/or amino acid sequence disclosures in patent applications...Disclosures Containing Nucleotide And/or Amino Acid Sequences § 1.821 Nucleotide and/or amino acid sequence disclosures in patent...

2011-07-01

361

40 CFR 721.10380 - Benzoic acid, 3-amino-2-mercapto-.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Benzoic acid, 3-amino-2-mercapto-. 721.10380...Substances § 721.10380 Benzoic acid, 3-amino-2-mercapto-. (a) Chemical...substance identified as benzoic acid, 3-amino-2-mercapto- (PMN...

2013-07-01

362

40 CFR 721.430 - Oxo-substituted amino-al-kanoic acid derivative.  

... false Oxo-substituted amino-al-kanoic acid derivative. 721.430...430 Oxo-substituted amino-al-kanoic acid derivative. (a) Chemical...generically as oxo-substituted amino al-kan-oic acid derivative (PMN No....

2014-07-01

363

40 CFR 721.430 - Oxo-substituted amino-al-kanoic acid derivative.  

Code of Federal Regulations, 2013 CFR

... false Oxo-substituted amino-al-kanoic acid derivative. 721.430...430 Oxo-substituted amino-al-kanoic acid derivative. (a) Chemical...generically as oxo-substituted amino al-kan-oic acid derivative (PMN No....

2013-07-01

364

Gustatory Responses of Eel Palatine Receptors to Amino Acids and Carboxylic Acids  

E-print Network

ABSTRACT The gustatory receptors of the eel palate were found to be extremely sensitive to amino acids and carboxylic acids. The results obtained are as follows: (a) 11 amino acids which are among naturally occurring amino acids elicited responses in the palatine nerve, but 9 amino acids did not elicit a response even at a high concentration. The effect of D-amino acids was always much less than that of their corresponding L-isomers. There was no appreciable difference in the effectiveness of an a-amino acid (a-alanine) and fl-amino acid (fl-alanine). (b) The threshold concentrations of the most potent amino acids (arginine, glycine) were between 10-s and 10-aM. A linear relation between the magnitude of the response and log stimulus concentration held for a wide concentration range for all the amino acids examined. (c) The palatine receptors responded sensitively to various carboxylic acid solutions whose pH was adjusted to neutral. The threshold concentrations varied between 10-4 and 10-7M. The magnitude of the response at 10-2M increased with an increase of carbon chain length. (d) The extent of cross-adaptation was examined with various combinations of amino acids. A variety of the response patterns showing complete cross-adaptation, no cross-adaptation, or synergetic interaction was observed. The synergetic interaction was also observed when one amino acid below its threshold concentration was added to the other amino acid. No cross-adaptation was observed between amino acids and fatty acids. (e) The treatment of the palate with papain led to loss of the responses to arginine, glycine, and histidine without affecting those to proline and acetic acid. The treatment with pronase E eliminated selectively the response to proline. The possibility that the eel gustatory receptors are responsible for sensing food at a distance was discussed.

Kiyonori Yoshii; Naoki Kamo; Kenzo Kurihara

365

Differentiation of Positional Isomers of Hybrid Peptides Containing Repeats of ?-Nucleoside Derived Amino Acid (?-Nda-) and L-Amino Acids by Positive and Negative Ion Electrospray Ionization Tandem Mass Spectrometry (ESI-MS n )  

NASA Astrophysics Data System (ADS)

A new class of positional isomeric pairs of -Boc protected oligopeptides comprised of alternating nucleoside derived ?-amino acid (?-Nda-) and L-amino acid residues (alanine, valine, and phenylalanine) have been differentiated by both positive and negative ion electrospray ionization ion-trap tandem mass spectrometry (ESI-MS n ). The protonated dipeptide positional isomers with ?-Nda- at the N-terminus lose CH3OH, NH3, and C2H4O2, whereas these processes are absent for the peptides with L-amino acids at the N-terminus. Instead, the presence of L-amino acids at the N-terminus results in characteristic retro-Mannich reaction involving elimination of imine. A good correlation has been observed between the conformational structure of the peptides and the abundance of y{n/+} and b{n/+} ions in MS n spectra. In the case of tetrapeptide isomers that are reported to form helical structures in solution phase, no y{n/+} and b{n/+} ions are observed when the corresponding amide -NH- participates in the helical structures. In contrast, significant y{n/+} and b{n/+} ions are formed when the amide -NH- is not involved in the H-bonding. In the case of tetra- and hexapeptides, it is observed that abundant b{n/+} ions are formed, presumably with stable oxazolone structures when the C-terminus of the b{n/+} ions possessed L-amino acid and the ?-Nda- at the C-terminus appears to prevent the cyclization process leading to the absence of corresponding b{n/+} ions.

Raju, B.; Ramesh, M.; Srinivas, R.; Chandrasekhar, S.; Kiranmai, N.; Sarma, V. U. M.

2011-04-01

366

Studies on the amino acid requirements of horses  

E-print Network

of Urea and Creatinine and Fraction of Filtered Urea Excreted, Experiment 4. 53 23 Percentage Change in Post-Prandial Serum Amino Acid Concentrations. 55 LIST OF TABLES IN APPENDIX Table Page 24 Growth and Feed Efficiency for Individual Foals... Excreted. 84 Table Page }'sating and PosL- ceding Serum Amino Acid ConccuLrations in Animal: Receiving Soybean Veal Ration. Ao Fasting and Post-feeding Serum Amino Acid Concentrations in Animal. Rc eiving 2ein I:ation. 88 CHAPTER I IHTROHUCTIOR...

Word, James Dewey

1968-01-01

367

Effects of branched-chain amino acids on protein turnover.  

PubMed

Amino acid availability rapidly regulates protein synthesis and degradation. Increasing amino acid concentrations above the levels found in post-absorptive plasma stimulates protein synthesis in a dose-dependent manner at the level of mRNA translation-initiation and inhibits protein degradation by inhibiting lysosomal autophagy. The anabolic effects of insulin on protein synthesis and protein degradation are exerted at the same sites (i.e., peptide chain initiation and lysosomal stabilization) allowing for a rapid synergistic response when both amino acids and insulin increase after a protein-containing meal. In perfused liver preparations, protein anabolic effects are exerted by a group of amino acids acting in concert. The BCAA are among the amino acids required for stimulation of hepatic protein synthesis, but there is no evidence that BCAA or leucine alone are effective. Leucine alone is an important inhibitor of hepatic protein degradation, but maximal inhibition requires in addition several other regulatory amino acids. In heart and skeletal muscle in vitro, increasing the concentration of the three BCAA or of leucine alone reproduces the effects of increasing the supply of all amino acids in stimulating protein synthesis and inhibiting protein degradation. Skeletal muscle is the largest repository of metabolically active protein and a major contributor to total body nitrogen balance. Supplying energy alone (i.e., carbohydrate and lipids) cannot prevent negative nitrogen balance (net protein catabolism) in animals or humans; only provision of amino acids allows the attainment of nitrogen balance. In rats and in humans nourished parenterally, provision of balanced amino acid solutions or of only the three BCAA cause similar improvements in nitrogen balance for several days. There is some evidence that infusions of leucine alone can stimulate muscle protein synthesis in vivo; the effect may be transitory and was not observed by all investigators; provisions of excess leucine alone does not seem to affect total body or muscle protein degradation in vivo. In postabsorptive rats, in vivo, infusion of the three BCAA together stimulates muscle protein synthesis as much as the infusion of a complete amino acid mixture or of a mixture of essential amino acids; the in vivo effect requires coinfusion of glucose or of small (physiological) doses of insulin, suggesting synergism between insulin and amino acids.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2656154

May, M E; Buse, M G

1989-05-01

368

Amino acid profile of milk-based infant formulas.  

PubMed

The protein content and amino acid profile of three milk-based infant formulas, two of which were powdered (adapted and follow-on) and the third liquid, were determined to check their compliance with the EU directive and to evaluate whether or not they fulfil an infant's nutritional needs. To obtain the amino acid profile proteins were subjected to acid hydrolysis, prior to which the sulfur-containing amino acids were oxidized with performic acid. The amino acids were derivatized with phenylisothiocyanate (PITC) and then determined by ion-pair reverse phase high performance liquid chromatography (HPLC) In the case of tryptophan a basic hydrolysis was applied and there was no need of derivatization. The protein contents of the analysed formulas were in the ranges established by the EU directive for these products and the amino acid contents were in the ranges reported by other authors for these types of formulas. In all cases the tryptophan content determined the value of the chemical score, which was always lower than 80% of the reference protein but in the ranges reported by other authors. The analysed adapted infant formula provides amino acids in amounts higher than the established nutritional requirements. PMID:11103301

Viadel, B; Alegriá, A; Farré, R; Abellán, P; Romero, F

2000-09-01

369

How amino acids and peptides shaped the RNA world.  

PubMed

The "RNA world" hypothesis is seen as one of the main contenders for a viable theory on the origin of life. Relatively small RNAs have catalytic power, RNA is everywhere in present-day life, the ribosome is seen as a ribozyme, and rRNA and tRNA are crucial for modern protein synthesis. However, this view is incomplete at best. The modern protein-RNA ribosome most probably is not a distorted form of a "pure RNA ribosome" evolution started out with. Though the oldest center of the ribosome seems "RNA only", we cannot conclude from this that it ever functioned in an environment without amino acids and/or peptides. Very small RNAs (versatile and stable due to basepairing) and amino acids, as well as dipeptides, coevolved. Remember, it is the amino group of aminoacylated tRNA that attacks peptidyl-tRNA, destroying the bond between peptide and tRNA. This activity of the amino acid part of aminoacyl-tRNA illustrates the centrality of amino acids in life. With the rise of the "RNA world" view of early life, the pendulum seems to have swung too much towards the ribozymatic part of early biochemistry. The necessary presence and activity of amino acids and peptides is in need of highlighting. In this article, we try to bring the role of the peptide component of early life back into focus. We argue that an RNA world completely independent of amino acids never existed. PMID:25607813

van der Gulik, Peter T S; Speijer, Dave

2015-01-01

370

Partial Molar Volumes of Some of ?-Amino Acids in Binary Aqueous Solutions of MgSO 4 ·7H 2 O at 298.15 K  

Microsoft Academic Search

The apparent molar volume, V\\u000a o\\u000a ?, 2, of glycine, alanine, ?-amino-n-butyric acid, valine and leucine have been determined in aqueous solutions of 0.25, 0.5 and 1.0 mol?dm?3 magnesium sulfate, and the partial specific volume from density measurements at 298.15 K. These data have been used to calculate the infinite dilution apparent molar volume, V\\u000a o\\u000a 2,m\\u000a , group contribution

Bairagi C. Mallick; Nand Kishore

2006-01-01

371

Polymers with complexing properties. Simple poly(amino acids)  

NASA Technical Reports Server (NTRS)

The free amino (0.3 equiv/residue) and carboxyl (0.5 equiv/residue) groups of thermal polylysine increased dramatically on treatment with distilled water. The total hydrolysis of such a polymer was abnormal in that only about 50% of the expected amino acids were recovered. Poly (lysine-co-alanine-co-glycine) under usual conditions hydrolyzed completely in 8 hours; whereas, when it was pretreated with diazomethane, a normal period of 24 hours was required to give (nearly) the same amounts of each free amino acid as compared with those obtained from the untreated polymer. The amino groups of the basic thermal poly(amino acids) were sterically hindered. The existence of nitrogen atoms linking two or three chains and reactive groups (anhydride, imine) were proposed.

Roque, J. M.

1978-01-01

372

Alteration of organic matter during infaunal polychaete gut passage and links to sediment organic geochemistry. Part I: Amino acids  

NASA Astrophysics Data System (ADS)

Of the factors which control the quantity and composition of organic matter (OM) buried in marine sediments, the links between infaunal ingestion and gut passage and sediment geochemistry have received relatively little attention. This study aimed to use feeding experiments and novel isotope tracing techniques to quantify amino acid net accumulation and loss during polychaete gut passage, and to link this to patterns of selective preservation and decay in sediments. Microcosms containing either Arenicolamarina or Hediste (formerly Nereis) diversicolor were constructed from defaunated sediment and filtered estuarine water, and maintained under natural temperature and light conditions. They were fed with 13C-labelled diatoms daily for 8 days, and animals were transferred into fresh, un-labelled sediment after ?20 days. Samples of fauna, microcosm sediment and faecal matter were collected after 8, ?20 and ?40 days, and analysed for their bulk isotopic signatures and 13C-labelled amino acid compositions. Bulk isotopic data showed that, consistent with their feeding modes, Hediste assimilated added 13C more quickly, and attained a higher labelling level than Arenicola. Both species retained the added 13C in their biomass even after removal from the food. A principal component analysis of 13C-labelled amino acid mole percentages showed clear differences in composition between the algae, faunal tissues, and sediment plus faecal matter. Further, the two species of polychaete showed different compositions in their tissues. The amino acids phenylalanine, valine, leucine, iso-leucine, threonine and proline showed net accumulation in polychaete tissues. Serine, methionine, lysine, aspartic and glutamic acids and tyrosine were rapidly lost through metabolism, consistent with their presence in easily digestible cell components (as opposed to cell walls which offer physical protection). All sample types (polychaete tissues, sediments and faecal matter) were enriched in labelled glycine. Possible mechanisms for this enrichment include accumulation through inclusion in tissues with long residence times, preferential preservation (i.e. selection against) during metabolism, production from other labelled amino acids during varied metabolic processes, and accumulation in refractory by-products of secondary bacterial production. Overall, similarities were observed between amino-acid decay patterns in faunated microcosms, afaunal controls, and those previously reported in marine sediments. Thus, while polychaete gut passage did produce compound-selective accumulation and losses of certain amino acids in polychaete tissues and faecal matter, the impact of polychaete gut passage on sediment organic geochemistry was difficult to deconvolve from microbial decay. Despite processing large volumes of organic matter, polychaetes may not have distinctive influence on sediment compositions, possibly because metabolic processes concerning amino acids may be broadly similar across a wide range of organisms.

Woulds, Clare; Middelburg, Jack J.; Cowie, Greg L.

2012-01-01

373

Biosynthesis of the proteasome inhibitor syringolin A: the ureido group joining two amino acids originates from bicarbonate  

PubMed Central

Background Syringolin A, an important virulence factor in the interaction of the phytopathogenic bacterium Pseudomonas syringae pv. syringae B728a with its host plant Phaseolus vulgaris (bean), was recently shown to irreversibly inhibit eukaryotic proteasomes by a novel mechanism. Syringolin A is synthesized by a mixed non-ribosomal peptide synthetase/polyketide synthetase and consists of a tripeptide part including a twelve-membered ring with an N-terminal valine that is joined to a second valine via a very unusual ureido group. Analysis of sequence and architecture of the syringolin A synthetase gene cluster with the five open reading frames sylA-sylE allowed to formulate a biosynthesis model that explained all structural features of the tripeptide part of syringolin A but left the biosynthesis of the unusual ureido group unaccounted for. Results We have cloned a 22 kb genomic fragment containing the sylA-sylE gene cluster but no other complete gene into the broad host range cosmid pLAFR3. Transfer of the recombinant cosmid into Pseudomonas putida and P. syringae pv. syringae SM was sufficient to direct the biosynthesis of bona fide syringolin A in these heterologous organisms whose genomes do not contain homologous genes. NMR analysis of syringolin A isolated from cultures grown in the presence of NaH13CO3 revealed preferential 13C-labeling at the ureido carbonyl position. Conclusion The results show that no additional syringolin A-specific genes were needed for the biosynthesis of the enigmatic ureido group joining two amino acids. They reveal the source of the ureido carbonyl group to be bicarbonate/carbon dioxide, which we hypothesize is incorporated by carbamylation of valine mediated by the sylC gene product(s). A similar mechanism may also play a role in the biosynthesis of other ureido-group-containing NRPS products known largely from cyanobacteria. PMID:19863801

Ramel, Christina; Tobler, Micha; Meyer, Martin; Bigler, Laurent; Ebert, Marc-Olivier; Schellenberg, Barbara; Dudler, Robert

2009-01-01

374

Characterisation of dissolved combined amino acids in marine waters.  

PubMed

Dissolved combined amino acids (DCAA) are important constituents of the dissolved organic nitrogen (DON) pool in marine environments, although little is known about their sources, dynamics and sinks. The DCAA pool consists of various compounds including proteins and peptides, proteins linked to sugars and amino acids adsorbed to humic and fulvic acids, clays and other materials. The proportions of each of these components and the extent to which they are used by microplankton living within the photic zone are not known. An investigation was carried out, using (15)N isotope dilution techniques, to determine the concentration and composition of dissolved amino acid pools in the marine environment. A near-shore seawater sample was collected and split into fractions to determine the concentrations of dissolved free amino acids (DFAA), DCAA and a <3 kDa dissolved peptide fraction (DPEP; obtained by ultrafiltration). DCAA and DPEP fractions were hydrolysed to yield free amino acids and all samples were analysed by gas chromatography/mass spectrometry (GC/MS) as isobutyloxycarbonyl/tert-butyldimethylsilyl derivatives. The DFAA was the smallest fraction representing approximately 1% of total dissolved amino acids. The majority of DCAA was contained in the low molecular weight DPEP fraction (90%) and was probably as a result of release from phytoplankton and degradation by heterotrophic bacteria. PMID:11466786

Sommerville, K; Preston, T

2001-01-01

375

Amino acid utilization by Aerobacter aerogenes and Escherichia coli  

E-print Network

A considerable amount of work has been done on the growth of A. aerogenes and E. coli in synthetic media, but little work has been undertaken on the utilization by these organisms of amino acids as comparative sources of ...

Herrera, Rodolfo Eduardo

1938-01-01

376

Isotopic analyses of amino acids from the Murchison meteorite  

NASA Technical Reports Server (NTRS)

An account is given of the results of H-2, C-13 isotopic analyses of the Murchison meteorite incorporating an ultrafiltration step to exclude the possibility of fine particulate contaminants. The meteorite's amino acids were chromatographically separated in order to preclude isotopic enrichment by basic compounds other than the amino acids. The results indicate that the Murchison amino acids are isotopically highly unusual; delta-C-13 is elevated by about 40 percent, and delta-D by fully 2500 percent. This high D content of the meteorite's alpha-amino acids may be due to the synthesis of their molecular precursors by low-temperature ion-molecule reactions in an interstellar cloud.

Pizzarello, S.; Cronin, J. R.; Krishnamurthy, R. V.; Epstein, S.

1991-01-01

377

Comparing Amino Acid Abundances and Distributions Across Carbonaceous Chondrite Groups  

NASA Technical Reports Server (NTRS)

Meteorites are grouped according to bulk properties such as chemical composition and mineralogy. These parameters can vary significantly among the different carbonaceous chondrite groups (CI, CM, CO, CR, CH, CB, CV and CK). We have determined the amino acid abundances of more than 30 primary amino acids in meteorites from each of the eight groups, revealing several interesting trends. There are noticeable differences in the structural diversity and overall abundances of amino acids between meteorites from the different chondrite groups. Because meteorites may have been an important source of amino acids to the prebiotic Earth and these organic compounds are essential for life as we know it, the observed variations of these molecules may have been important for the origins of life.

Burton, Aaron S.; Callahan, Michael P.; Glavin, Daniel P.; Elsila, Jamie E.; Dworkin, Jason P.

2012-01-01

378

Amino acid signalling upstream of mTOR  

PubMed Central

Mammalian target of rapamycin (mTOR) is a conserved Ser/Thr kinase that is part of mTOR complex 1 (mTORC1), a master regulator that couples amino acid availability to cell growth and autophagy. Multiple cues modulate mTORC1 activity, such as growth factors, stress, energy status and amino acids. Although amino acids are key environmental stimuli, exactly how they are sensed and how they activate mTORC1 is not fully understood. Recently, a model has emerged whereby mTORC1 activation occurs at the lysosome and is mediated through an amino acid sensing cascade involving RAG GTPases, Ragulator and vacuolar H+-ATPase (v-ATPase). PMID:23361334

Jewell, Jenna L.; Russell, Ryan C.; Guan, Kun-Liang

2014-01-01

379

Inhibitors of amino acids biosynthesis as antifungal agents.  

PubMed

Fungal microorganisms, including the human pathogenic yeast and filamentous fungi, are able to synthesize all proteinogenic amino acids, including nine that are essential for humans. A number of enzymes catalyzing particular steps of human-essential amino acid biosynthesis are fungi specific. Numerous studies have shown that auxotrophic mutants of human pathogenic fungi impaired in biosynthesis of particular amino acids exhibit growth defect or at least reduced virulence under in vivo conditions. Several chemical compounds inhibiting activity of one of these enzymes exhibit good antifungal in vitro activity in minimal growth media, which is not always confirmed under in vivo conditions. This article provides a comprehensive overview of the present knowledge on pathways of amino acids biosynthesis in fungi, with a special emphasis put on enzymes catalyzing particular steps of these pathways as potential targets for antifungal chemotherapy. PMID:25408465

Jastrz?bowska, Kamila; Gabriel, Iwona

2015-02-01

380

The adsorption of valine on cation-exchanged montmorillonites  

Microsoft Academic Search

The interfacial reaction of valine was systematically studied on the surface of different cation-exchanged montmorillonites, namely calcium-, copper-, zinc-montmorillonite, and montmorillonite KSF. The exchanged cations were selected on the basis of stability of their valine complexes. At first the interfacial acid\\/base properties of cation exchanged montmorillonites were studied: the stability constants of the ion exchange processes on the layer charges

Noémi M. Nagy; József Kónya

2004-01-01

381

The stability of amino acids at submarine hydrothermal vent temperatures  

NASA Technical Reports Server (NTRS)

It has been postulated that amino acid stability at hydrothermal vent temperatures is controlled by a metastable thermodynamic equilibrium rather than by kinetics. Experiments reported here demonstrate that the amino acids are irreversibly destroyed by heating at 240 C and that quasi-equilibrium calculations give misleading descriptions of the experimental observations. Equilibrium thermodynamic calculations are not applicable to organic compounds under high-temperature submarine vent conditions.

Bada, Jeffrey L.; Miller, Stanley L.; Zhao, Meixun

1995-01-01

382

Neuropeptide Y: Complete Amino Acid Sequence of the Brain Peptide  

Microsoft Academic Search

The amino acid sequence of neuropeptide Y, a 36-residue peptide recently isolated from porcine brain, has been determined by using high performance liquid chromatography for separation of its tryptic and chymotryptic fragments and subsequent sequence analysis of the isolated fragments by an improved dansyl Edman subtractive technique. The amino acid sequence of neuropeptide Y has been found to be: Tyr-Pro-Ser-Lys-Pro-Asp-Asn-Pro-Gly-Glu-Asp-Ala-Pro-Ala-Glu-Asp-Leu-Ala-

Kazuhiko Tatemoto

1982-01-01

383

Polypeptide having an amino acid replaced with N-benzylglycine  

DOEpatents

The present invention relates to one or more polypeptides having useful biological activity in a mammal, which comprise: a polypeptide related to bradykinin of four to ten amino acid residues wherein one or more specific amino acids in the polypeptide chain are replaced with achiral N-benzylglycine. These polypeptide analogues have useful potent agonist or antagonist pharmacological properties depending upon the structure. A preferred polypeptide is (N-benzylglycine.sup.7)-bradykinin.

Mitchell, Alexander R. (Livermore, CA); Young, Janis D. (Los Angeles, CA)

1996-01-01

384

Quantitative analysis of amino acid mixtures by mass spectrometry  

E-print Network

QUANTITATIVE ANALYSIS OF AMINO ACID MIXTURES BY MASS SPECTROMETRY A Thesis by DAMES SPENCER BIRD Submitted to the Graduate College of Texas AhM University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE August... 1971 Ma j or Subject: Biochemistry QDANTITATIVE ANALYSIS OE AMINO ACID MIXTURES BY MASS SPECTROMETRY A Thesis by JAMES SPENCER BIRD Approved as to style and content by: (Chairman oE Committ ) (Head of- Department. ) (Member) (Member) August...

Bird, James Spencer

1971-01-01

385

Taurine: new implications for an old amino acid  

Microsoft Academic Search

Taurine is a semi-essential amino acid and is not incorporated into proteins. In mammalian tissues, taurine is ubiquitous and is the most abundant free amino acid in the heart, retina, skeletal muscle, brain, and leukocytes. In fact, taurine reaches up to 50 mM concentration in leukocytes. Taurine has been shown to be tissue-protective in many models of oxidant-induced injury. One

Georgia B. Schuller-Levis

2003-01-01

386

Amino acid uptake in deciduous and coniferous taiga ecosystems  

Microsoft Academic Search

We measured in situ uptake of amino acids and ammonium across deciduous and coniferous taiga forest ecosystems in interior Alaska to examine the idea that late successional (coniferous) forests rely more heavily on dissolved organic nitrogen (DON), than do early successional (deciduous) ecosystems. We traced 15N-NH4+ and 13C-15N-amino acids from the soil solution into plant roots and soil pools over

Knut Kielland; Jack McFarland; Karl Olson

2006-01-01

387

GTP Dysregulation in Bacillus subtilis Cells Lacking (p)ppGpp Results in Phenotypic Amino Acid Auxotrophy and Failure To Adapt to Nutrient Downshift and Regulate Biosynthesis Genes  

PubMed Central

The nucleotide (p)ppGpp inhibits GTP biosynthesis in the Gram-positive bacterium Bacillus subtilis. Here we examined how this regulation allows cells to grow in the absence of amino acids. We showed that B. subtilis cells lacking (p)ppGpp, due to either deletions or point mutations in all three (p)ppGpp synthetase genes, yjbM, ywaC, and relA, strongly require supplementation of leucine, isoleucine, valine, methionine, and threonine and modestly require three additional amino acids. This polyauxotrophy is rescued by reducing GTP levels. Reduction of GTP levels activates transcription of genes responsible for the biosynthesis of the five strongly required amino acids by inactivating the transcription factor CodY, which represses the ybgE, ilvD, ilvBHC-leuABCD, ilvA, ywaA, and hom-thrCB operons, and by a CodY-independent activation of transcription of the ilvA, ywaA, hom-thrCB, and metE operons. Interestingly, providing the eight required amino acids does not allow for colony formation of (p)ppGpp0 cells when transitioning from amino acid-replete medium to amino acid-limiting medium, and we found that this is due to an additional role that (p)ppGpp plays in protecting cells during nutrient downshifts. We conclude that (p)ppGpp allows adaptation to amino acid limitation by a combined effect of preventing death during metabolic transitions and sustaining growth by activating amino acid biosynthesis. This ability of (p)ppGpp to integrate a general stress response with a targeted reprogramming of gene regulation allows appropriate adaptation and is likely conserved among diverse bacteria. PMID:24163341

Kriel, Allison; Brinsmade, Shaun R.; Tse, Jessica L.; Tehranchi, Ashley K.; Bittner, Alycia N.; Sonenshein, Abraham L.

2014-01-01

388

Exploring DNA binding and nucleolytic activity of few 4-aminoantipyrine based amino acid Schiff base complexes: a comparative approach.  

PubMed

A series of novel Co(II), Cu(II), Ni(II) and Zn(II) complexes were synthesized from Schiff base(s), obtained by the condensation of 4-aminoantipyrine with furfural and amino acid (glycine(L1)/alanine(L2)/valine(L3)) and respective metal(II) chloride. Their structural features and other properties were explored from the analytical and spectral methods. The binding behaviors of the complexes to calf thymus DNA were investigated by absorption spectra, viscosity measurements and cyclic voltammetry. The intrinsic binding constants for the above synthesized complexes are found to be in the order of 10(2) to 10(5) indicating that most of the synthesized complexes are good intercalators. The binding constant values (Kb) clearly indicate that valine Schiff-base complexes have more intercalating ability than alanine and glycine Schiff-base complexes. The results indicate that the complexes bind to DNA through intercalation and act as efficient cleaving agents. The in vitro antibacterial and antifungal assay indicates that these complexes are good antimicrobial agents against various pathogens. The IC50 values of [Ni(L1)2] and [Zn(L1)2] complexes imply that these complexes have preferable ability to scavenge hydroxyl radical. PMID:24566120

Raman, N; Sakthivel, A; Pravin, N

2014-05-01

389

5,6,9/99 Neuman Chapter 22 Peptides, Proteins, and -Amino Acids  

E-print Network

5,6,9/99 Neuman Chapter 22 0 Chapter 22 Peptides, Proteins, and -Amino Acids from Organic Chemistry. Peptides, Proteins, and -Amino Acids 23. Nucleic Acids, Proteins, and -Amino Acids Preview 22-3 22.1 Peptides 22-3 Peptide Structure (22.1A) 22-3 -Amino Acids

Reed, Christopher A.

390

Amino acid analysis using core-shell particle column.  

PubMed

In this study, the separation efficiency of a core-shell particle column was compared with particle-packed and monolithic silica columns, which showed that the core-shell particle column had a smaller theoretical plate height and that its separation efficiency was not affected significantly by the increase in flow rate. A fast HPLC method using a core-shell particle column was developed for the determination of amino acids. 4-Fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) was used as a fluorescence derivatization reagent for amino acids, followed by separation on a core-shell Kinetex C18 column. The analysis time for 21 NBD-amino acids was within 7min, which was faster than that in our previous studies with conventional particle-packed columns or monolithic silica columns. The linearities of the calibration curves for all the amino acids were found to be good over a range of injection amounts from 40fmol to 40pmol. The accuracies for the amino acid determinations were 90.9-107%. The method was proved to have potential for the fast determination of amino acids in biological samples. PMID:23022276

Song, Yanting; Funatsu, Takashi; Tsunoda, Makoto

2013-05-15

391

On the utility of alternative amino acid scripts.  

PubMed

In this work we propose the hypothesis that replacing the current system of representing the chemical entities known as amino acids using Latin letters with one of several possible alternative symbolic representations will bring significant benefits to the human construction, modification, and analysis of multiple protein sequence alignments. We propose ways in which this might be done without prescribing the choice of actual scripts used. Specifically we propose and explore three ways to encode amino acid texts using novel symbolic alphabets free from precedents. Primary orthographic encoding is the direct substitution of a new alphabet for the standard, Latin-based amino acid code. Secondary encoding imposes static residue groupings onto the orthography of the alphabet by manipulating the shape and/or orientation of amino acid symbols. Tertiary encoding renders each residue as a composite symbol; each such symbol thus representing several alternative amino acid groupings simultaneously. We also propose that the use of a new group-focussed alphabet will free the colouring of amino acid residues often used as a tool to facilitate the representation or construction of multiple alignments for other purposes, possibly to indicate dynamic properties of an alignment such as position-wise residue conservation. PMID:22829727

Flower, Darren R

2012-01-01

392

Extraterrestrial Amino Acids in Ureilites Including Almahata Sitta  

NASA Technical Reports Server (NTRS)

Ureilites are a class of meteorites that lack chondrules (achondrites) but have relatively high carbon abundances, averaging approx.3 wt %. Using highly sensitive liquid chromatography coupled with UV fluorescence and time-of-flight mass spectrometry (LC-FD/ToF-MS), it was recently determined that there are amino acids in. fragment 94 of the Almahata Sitta ureilite[l]. Based on the presence of amino acids that are rare in the Earth's biosphere, as well as the near-racemic enantiomeric ratios of marry of the more common amino acids, it was concluded that most of the detected amino acids were indigenous to the meteorite. Although the composition of the Almahata Sitta ureilite appears to be unlike other recovered ureilites, the discovery of amino acids in this meteorite raises the question of whether other ureilites rnav also contain amino acids. Herein we present the results of LC-FDlTo.F-MS analyses of: a sand sample from the Almahata Sitta strewn held, Almahata Sitta fragments 425 (an ordinary H5 chondrite) and 427 (ureilite), as well as an Antarctic ureilite (Allan lulls, ALHA 77257).

Burton, A. S.; Glavin, D. P.; Callahan, M. P.; Dworkin, J. P.

2011-01-01

393

Carbobenzoxy amino acids: Structural requirements for cholecystokinin receptor antagonist activity  

SciTech Connect

The authors used dispersed acini prepared from guinea pig pancreas to examine 28 carbobenzoxy (CBZ) amino acids for their abilities to function as cholecystokinin receptor antagonists. All amino acid derivatives tested, except for CBZ-alanine, CBZ-glycine, and N alpha-CBZ- lysine, were able to inhibit the stimulation of amylase secretion caused by the C-terminal octapeptide of cholecystokinin. In general, there was a good correlation between the ability of a carbobenzoxy amino acid to inhibit stimulated amylase secretion and the ability of the amino acid derivative to inhibit binding of /sup 125/I-cholecystokinin. The inhibition of cholecystokinin-stimulated amylase secretion was competitive, fully reversible, and specific for those secretagogues that interact with the cholecystokinin receptor. The potencies with which the various carbobenzoxy amino acids inhibited the action of cholecystokinin varied 100-fold and CBZ-cystine was the most potent cholecystokinin receptor antagonist. This variation in potency was primarily but not exclusively a function of the hydrophobicity of the amino acid side chain.

Maton, P.N.; Sutliff, V.E.; Jensen, R.T.; Gardner, J.D.

1985-04-01

394

Evaluation of Amino Acids as Turfgrass Nematicides1  

PubMed Central

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.

2010-01-01

395

Autophagy and aging--importance of amino acid levels.  

PubMed

Melendez et al. [Science 301 (2003) 1387] have recently shown that the increased longevity of Caenorhabditis elegans mutants with defective Daf-2 protein, i.e. an insulin receptor analog, involves increased autophagy. Autophagy increases the free amino acid pool and is in certain cells essential for survival at times of limited amino acid availability. In addition, autophagy plays an important role in the turnover of proteins and organelles including mitochondria. The autophagic activity is sensitive to changes in physiological conditions, i.e. it is strongly inhibited by an increase in amino acid concentrations or in insulin receptor signaling. In line with this fact, clinical studies indicate that autophagy mainly occurs at times of low plasma amino acid and insulin concentrations in the post-absorptive (fasted) state, and that the post-absorptive amino acid-sensitive protein catabolism may be taken as a bona fide indicator of autophagic activity. The increased longevity of insulin receptor mutants or of organisms subjected to calorie restriction may, therefore, be attributed to an increase in autophagic activity. Importantly, the autophagic activity decreases with age. Recent studies suggest that this decrease may result from an age-related increase in post-absorptive amino acid levels and/or from an increase in baseline insulin receptor signaling. If so, it is potentially reversible. PMID:15104104

Dröge, Wulf

2004-03-01

396

Did Evolution Select a Nonrandom "Alphabet" of Amino Acids?  

NASA Astrophysics Data System (ADS)

The last universal common ancestor of contemporary biology (LUCA) used a precise set of 20 amino acids as a standard alphabet with which to build genetically encoded protein polymers. Considerable evidence indicates that some of these amino acids were present through nonbiological syntheses prior to the origin of life, while the rest evolved as inventions of early metabolism. However, the same evidence indicates that many alternatives were also available, which highlights the question: what factors led biological evolution on our planet to define its standard alphabet? One possibility is that natural selection favored a set of amino acids that exhibits clear, nonrandom properties - a set of especially useful building blocks. However, previous analysis that tested whether the standard alphabet comprises amino acids with unusually high variance in size, charge, and hydrophobicity (properties that govern what protein structures and functions can be constructed) failed to clearly distinguish evolution's choice from a sample of randomly chosen alternatives. Here, we demonstrate unambiguous support for a refined hypothesis: that an optimal set of amino acids would spread evenly across a broad range of values for each fundamental property. Specifically, we show that the standard set of 20 amino acids represents the possible spectra of size, charge, and hydrophobicity more broadly and more evenly than can be explained by chance alone.

Philip, Gayle K.; Freeland, Stephen J.

2011-04-01

397

The spark discharge synthesis of amino acids from various hydrocarbons  

NASA Technical Reports Server (NTRS)

The spark discharge synthesis of amino acids using an atmosphere of CH4+N2+H2O+NH3 has been investigated with variable pNH3. The amino acids produced using higher hydrocarbons (ethane, ethylene, acetylene, propane, butane, and isobutane) instead of CH4 were also investigated. There was considerable range in the absolute yields of amino acids, but the yields relative to glycine (or alpha-amino-n-butyric acid) were more uniform. The relative yields of the C3 to C6 aliphatic alpha-amino acids are nearly the same (with a few exceptions) with all the hydrocarbons. The glycine yields are more variable. The precursors to the C3-C6 aliphatic amino acids seem to be produced in the same process, which is separate from the synthesis of glycine precursors. It may be possible to use these relative yields as a signature for a spark discharge synthesis provided corrections can be made for subsequent decomposition events (e.g. in the Murchison meteorite).

Ring, D.; Miller, S. L.

1984-01-01

398

Improving phylogenetic inference with a semiempirical amino acid substitution model.  

PubMed

Amino acid substitution matrices describe the rates by which amino acids are replaced during evolution. In contrast to nucleotide or codon models, amino acid substitution matrices are in general parameterless and empirically estimated, probably because there is no obvious parametrization for amino acid substitutions. Principal component analysis has previously been used to improve codon substitution models by empirically finding the most relevant parameters. Here, we apply the same method to amino acid substitution matrices, leading to a semiempirical substitution model that can adjust the transition rates to the protein sequences under investigation. Our new model almost invariably achieves the best likelihood values in large-scale comparisons with established amino acid substitution models (JTT, WAG, and LG). In particular for longer alignments, these likelihood gains are considerably larger than what could be expected from simply having more parameters. The application of our model differs from that of mixture models (such as UL2 or UL3), as we optimize one rate matrix per alignment, whereas mixture models apply the variation per alignments site. This makes our model computationally more efficient, while the performance is comparable to that of UL3. Applied to the phylogenetic problem of the origin of placental mammals, our new model and the UL3 mixed model are the only ones of the tested models that cluster Afrotheria and Xenarthra into a clade called Atlantogenata, which would be in correspondence with recent findings using more sophisticated phylogenetic methods. PMID:23002090

Zoller, Stefan; Schneider, Adrian

2013-02-01

399

Detection of trace amino acid biomarkers in ice from extreme environments with the Mars Organic Analyzer  

NASA Astrophysics Data System (ADS)

A portable microfabricated capillary electrophoresis (CE) system named the Mars Organic Analyzer (MOA) has been developed to analyze fluorescently-labeled biomarkers including amino acids, amines, nucleobases, and amino sugars with the goal of life detection on Mars (1,2). This system consists of a multilayer microfabricated glass wafer containing electrophoresis channels as well as microfluidic valves and pumps for sample manipulation, a confocal laser excitation and fluorescence detection system, and integrated CE power supplies. The MOA has been successfully field tested in the Panoche Valley, CA and in the Atacama Desert, Chile, detecting amino acids at the ppb levels (3). In addition, this technology has been shown to be effective in screening the formation of biogenic amines during fermentation (4). The MOA is a part of the Urey instrument package that has been selected for the 2013 European ExoMars mission by ESA. The identification of recent gully erosion sites, observations of ice on and beneath the surface of Mars, and the discovery of large reservoirs of sub-surface ice on Mars point to water-ice as an important target for astrobiological analyses (5). In addition, the ice moons Europa and Enceladus are of astrobiological interest due to the possibility that they may contain liquid water under their ice crusts. Consequently, we explore here the use of the MOA instrument for the analysis of amino acids in polar ice samples. Soil extracts as well as concentrated icecore samples tend to be highly saline and inhomogeneous. Furthermore, brine pockets in ice form potential refugia for extant extra-terrestrial life, rendering near surface ice a key target for the search for a record of past life on the planet (6). Therefore, we have determined the effect of salinity on sample injection parameters in ice-core samples retrieved from Greenland. The amino acids valine, alanine/serine, glycine, glutamic acid, and aspartic acid were found in the parts-per-billion range from these ice-core samples. Chiral analysis of these samples yielded D/L ratios of 0.51/0.09 for alanine/serine and 0.14/0.06 for aspartic acid. Individual amino acids in the parts-per-trillion range were found in Antarctic ice samples collected from the surface of a meteorite collection area. The distinct amino acid and amine content of these samples indicates that further biomarker characterization of ice samples as a function of sampling location, depth, and structural features will be highly informative. The rapid sensitive analysis capabilities demonstrated here establish the feasibility of using the MOA to analyze the biomarker content of ice samples in planetary exploration. 1. Skelley, A. M.; Scherer, J. R.; Aubrey, A. D.; Grover, W. H.; Ivester, R. H. C., Ehrenfreund, P.; Grunthaner, F. J.; Bada, J. L.; Mathies, R. A. Proceedings of the National Academy of Sciences, U.S.A., 2005, 192, 1041-1046. 2. Skelley, A. M., Cleaves, H. J., Jayarajah, C. N., Bada, J. L. and Mathies, R. A., Astrobiology 2006, 6, 824-837. 3. Skelley, A. M., Aubrey, A. D., Willis, P. A., Amashukeli, X., Ehrenfreuend, P. , Bada, J. L., Grunthaner, F. J. and Mathies, R. A. Journal of Geophysical Research 2007, 112, G04S11 4. Jayarajah, C.N., Skelley, A.M., Fortner, A.D., and Mathies, R.A., Analytical Chemistry, 2007, 79, 21, 8162-8169. 5. Sanderson, K., Nature 2006, 414. 800-801. 6. Price, B.P. Proceedings of the National Academy of Sciences, U.S.A., 2000, 97, 1247-1251.

Jayarajah, Christine; Jayarajah, Christine; Botta, Oliver; Aubrey, Andrew; Parker, Eric; Bada, Jeffrey; Mathies, Richard

400

Sublimation of natural amino acids and induction of asymmetry by meteoritic amino acids  

NASA Astrophysics Data System (ADS)

It is believed that the homochirality of building blocks of life like amino acids (AAs) and sugars is a prerequisite requirement for the origin and evolution of life. Among different mechanisms that might have triggered the initial disparity in the enantiomeric ratio on the primitive Earth, the key roles were assigned to: (i) local chiral symmetry breaking and (ii) the inflow of extraterrestrial matter (eg the carbonaceous meteorites containing non-racemic AAs). Recently it has been revealed that sublimation, a subject almost completely neglected for a long time, gives a pathway to enantioenrichment of natural AAs (1,2 and references herein). Sublimation is however one of the key physical processes that occur on comets. Starting from a mixture with a low content of an enantiopure AA, a partial sublimation gives an important enrichment of the sublimate (1,2). The resulted disparity in the ratio between enantiomers of a partial sublimate is determined by the crystalline nature of the starting mixture: we observed a drastic difference in the behavior of (i) mixtures based on true racemic compounds and (ii) mechanical mixtures of two enantiopure solid phases. On the other hand, combination of crystallization and sublimation can lead to segregation of enantioenriched fractions starting from racemic composition of sublimable aliphatic AAs (Ala, Leu, Pro, Val) in mixtures with non-volatile enantiopure ones (Asn, Asp, Glu, Ser, Thr) (3). The resulted sense of chirality correlates with the handedness of the non-volatile AAs: the observed changes in enantiomeric ratios clearly demonstrate the preferential homochiral interactions and a tendency of natural amino acids to homochiral self-organization. It is noteworthy that just these 5 (Asn, Asp, Glu, Ser, Thr) out of 22 proteinogenic amino acids are able to local symmetry breaking. On the other hand, recent data on the enantiomeric composition of the Tagish Lake, a C2-type carbonaceous meteorite, revealed a large L-enantiomeric excess of Asp and Glu (4) that we used in our experiments. These experimental data may shed some light on one of the facets of complex and mysterious preobiotic processes that eventually could have led to the origin of life. References: 1. Bellec A, Guillemin JC. Chem Commun 2010, 46:1482-1484. 2. Tarasevych AV, Sorochinsky AE, Kukhar VP, Chollet A, Daniellou R, Guillemin JC. J Org Chem 2013, 78:10530-10533. 3. Tarasevych AV, Sorochinsky AE, Kukhar VP, Guillemin JC. Orig Life Evol Biosph 2013, 43:129-135. 4. Glavin DP, Elsila JE, Burton AS, Callahan MP, Dworkin JP, Hilts RW, Herd CDK. Meteor Planet Sci 2012, 47:1347-1364.

Tarasevych, Arkadii V.; Guillemin, Jean-Claude

401

Simultaneous quantification of amino acids and Amadori products in foods through ion-pairing liquid chromatography-high-resolution mass spectrometry.  

PubMed

The formation of the Amadori products (APs) is the first key step of Maillard reaction. Only few papers have dealt with simultaneous quantitation of amino acids and corresponding APs (1-amino-1-deoxy-2-ketose). Chromatographic separation of APs is affected by several drawbacks mainly related to their poor retention in conventional reversed phase separation. In this paper, a method for the simultaneous quantification of amino acids and their respective APs was developed combining high-resolution mass spectrometry with ion-pairing liquid chromatography. The limit of detection was 0.1 ng/mL for tryptophan, valine and arginine, while the limit of quantification ranged from 2 to 5 ng/mL according to the specific sensitivity of each analyte. The relative standard deviation % was lower than 10 % and the coefficient of correlation was higher than 0.99 for each calibration curve. The method was applied to milk, milk-based products, raw and processed tomato. Among the analyzed products, the most abundant amino acid was glutamic acid (16,646.89 ± 1,385.40 µg/g) and the most abundant AP was fructosyl-arginine in tomato puree (774.82 ± 10.01 µg/g). The easiness of sample preparation coupled to the analytical performances of the proposed method introduced the possibility to use the pattern of free amino acids and corresponding APs in the evaluation of the quality of raw food as well as the extent of thermal treatments in different food products. PMID:25323735

Troise, Antonio Dario; Fiore, Alberto; Roviello, Giovanni; Monti, Simona Maria; Fogliano, Vincenzo

2015-01-01

402

On the abiotic formation of amino acids. I - HCN as a precursor of amino acids detected in extracts of lunar samples. II - Formation of HCN and amino acids from simulated mixtures of gases released from lunar samples  

NASA Technical Reports Server (NTRS)

Two studies on the abiotic formation of amino acids are presented. The first study demonstrates the role of hydrogen cyanide as a precursor of amino acids detected in extracts of lunar samples. The formation of several amino acids, including glycine, alanine, aspartic acid, and glutamic acid, under conditions similar to those used for the analysis of lunar samples is demonstrated. The second study investigates the formation of hydrogen cyanide as well as amino acids from lunar-sample gas mixtures under electrical discharge conditions. These results extend the possibility of synthesis of amino acids to planetary bodies with primordial atmospheres less reducing than a mixture of methane, ammonia, hydrogen and water.

Yuasa, S.; Flory, D.; Basile, B.; Oro, J.

1984-01-01

403

Functional Analysis of Fructosyl-Amino Acid Oxidases of Aspergillus oryzae  

PubMed Central

Three active fractions of fructosyl-amino acid oxidase (FAOD-Ao1, -Ao2a, and -Ao2b) were isolated from Aspergillus oryzae strain RIB40. N-terminal and internal amino acid sequences of FAOD-Ao2a corresponded to those of FAOD-Ao2b, suggesting that these two isozymes were derived from the same protein. FAOD-Ao1 and -Ao2 were different in substrate specificity and subunit assembly; FAOD-Ao2 was active toward N?-fructosyl N?-Z-lysine and fructosyl valine (Fru-Val), whereas FAOD-Ao1 was not active toward Fru-Val. The genes encoding the FAOD isozymes (i.e., FAOAo1 and FAOAo2) were cloned by PCR with an FAOD-specific primer set. The deduced amino acid sequences revealed that FAOD-Ao1 was 50% identical to FAOD-Ao2, and each isozyme had a peroxisome-targeting signal-1, indicating their localization in peroxisomes. The genes was expressed in Escherichia coli and rFaoAo2 showed the same characteristics as FAOD-Ao2, whereas rFaoAo1 was not active. FAOAo2 disruptant was obtained by using ptrA as a selective marker. Wild-type strain grew on the medium containing Fru-Val as the sole carbon and nitrogen sources, but strain ?faoAo2 did not grow. Addition of glucose or (NH4)2SO4 to the Fru-Val medium did not affect the assimilation of Fru-Val by wild-type, indicating glucose and ammonium repressions did not occur in the expression of the FAOAo2 gene. Furthermore, conidia of the wild-type strain did not germinate on the medium containing Fru-Val and NaNO2 as the sole carbon and nitrogen sources, respectively, suggesting that Fru-Val may also repress gene expression of nitrite reductase. These results indicated that FAOD is needed for utilization of fructosyl-amino acids as nitrogen sources in A. oryzae. PMID:15466528

Akazawa, Shin-ichi; Karino, Tetsuya; Yoshida, Nobuyuki; Katsuragi, Tohoru; Tani, Yoshiki

2004-01-01

404

Amino acid transport in Myxicola giant axon: stability of the amino acid pool, taurine efflux, and trans effect of sodium  

PubMed Central

1. The giant axon of Myxicola infundibulum was assessed for its suitability as a model preparation for study of amino acid transport mechanisms. 2. The amino acid composition of axoplasm was measured and compared with those of coelomic fluid, muscle and axon sheath. The axoplasmic composition is unique. Axoplasm/coelomic fluid concentration ratios are all much larger than 1. The axoplasmic amino acid concentrations are (mmol/kg plasm): cysteic acid (104), aspartic acid (75), glutamic acid (10), taurine (64), serine (5), glycine (191) and alanine (5). Other amino acids or primary amines, if present, must have concentrations of less than 1 mm. 3. The size of the sheath amino acid pool is 12% or less of the axoplasmic pool. 4. The amino acid pool of axons soaked in sea water for up to 24 h is stable. Removal of Na from sea water causes a large increase of net efflux and net production of amino acids. 5. Net amino acid production can not be detected in sheath. Metabolic production occurs in axoplasm with little accumulation. Time scales for production and net efflux are therefore similar. 6. The Myxicola axon has a vigorous amino acid metabolism and transport systems capable of relatively large fluxes. Homeostasis is strongly linked to Na and may involve Na-coupled co-transport. Conservation of transmembrane amino acid gradients could be promoted in part by trans inhibition of efflux by external Na. 7. Taurine is a useful model substrate because it is not catabolized in Myxicola and its net efflux is sensitive to Na. [3H]taurine efflux was measured from injected axons. Fluxes and internally recorded action potentials are stable for up to 6 h. 8. Axon sheaths take up [3H]taurine from 10 mm-taurine sea water with an apparent half-time of 5 h. [3H]taurine washout from the apparent extracellular space has a half-time of 5 min. Washout from sheath cells has a half-time of 2-3 h. Sheath is not an important parallel compartment for taurine fluxes in the axon. 9. Taurine efflux has a Q10 of 1·8. 10. Taurine efflux is insensitive to external taurine concentrations up to 10 mm. 11. Taurine efflux is sensitive to external Na, but only if internal Na is high. 12. Taurine is transported by a low-affinity Na-dependent system in Myxicola axon. Results could be explained by a carrier which is more mobile in the empty state than in the substrate-loaded state. Trans inhibition of taurine efflux by external Na is an important property of the system, and contributes to conservation of axoplasmic taurine. PMID:7310729

Horn, Lyle W.

1981-01-01

405

A single mechanism for the stimulation of insulin release and 86Rb+ efflux from rat islets by cationic amino acids  

PubMed Central

The mechanisms by which cationic amino acids influence pancreatic B-cell function have been studied by monitoring simultaneously 86Rb+ efflux and insulin release from perifused rat islets. The effects of two reference amino acids arginine and lysine were compared with those of closely related substances to define the structural requirements for recognition of these molecules as secretagogues. Arginine accelerated 86Rb+ efflux and increased insulin release in the absence or in the presence of 7mm-glucose. Its effects on efflux did not require the presence of extracellular Ca2+ or Na+, but its insulinotropic effects were suppressed in a Ca2+-free medium and inhibited in an Na+-free medium. Among arginine derivatives, only 2-amino-3-guanidinopropionic acid mimicked its effects on 86Rb+ efflux and insulin release; citrulline, guanidinoacetic acid, 3-guanidinopropionic acid and guanidine were inactive. Norvaline and valine also increased 86Rb+ efflux, but their effect required the presence of extracellular Na+; they did not stimulate insulin release. Lysine as well as the shorter-chain cationic amino acids ornithine and 2,4-diaminobutyric acid accelerated 86Rb+ efflux in a Ca2+- and Na+-independent manner. Their stimulation of insulin release was suppressed by Ca2+ omission, but only partially inhibited in an Na+-free medium. The uncharged glutamine and norleucine increased the rate of 86Rb+ efflux in the presence of glucose, only if extracellular Na+ was present. Norleucine slightly increased release in a Ca2+- and Na+-dependent manner. The effects of lysine on efflux and release were not mimicked by other related substances such as 1,5-diaminopentane and 6-aminohexanoic acid. The results suggest that the depolarizing effect of cationic amino acids is due to accumulation of these positively charged molecules in B-cells. This causes acceleration of the efflux of K+ (86Rb+) and activation of the influx of Ca2+ (which triggers insulin release). The prerequisite for the stimulation of B-cells by this mechanism appears to be the presence of a positive charge on the side chain of the amino acid, rather than a specific group. PMID:6818952

Charles, Stanislas; Tamagawa, Tatsuo; Henquin, Jean-Claude

1982-01-01

406

Plasma tryptophan and total neutral amino acid levels in men: influence of hyperinsulinemia and age.  

PubMed

Because of the well-recognized age-related changes in peripheral tissue sensitivity to insulin and the demonstrated impact of insulin on blood amino acid profiles in young individuals, we evaluated the influence of insulin level and age on the concentrations of tryptophan and its ratio to the sum of the large neutral amino acids (LNAA). The ratio of the plasma concentrations of tryptophan and the LNAA (leucine, isoleucine, valine, tyrosine, and phenylalanine), may be an important determinant of the rate at which tissues synthesize neurotransmitters, such as catecholamines and serotonin. Each of five healthy young (21 to 34 yr) and five healthy old subjects (67 to 85 yr) received, on separate occasions, euglycemic insulin infusions at rates of 6, 10, 30, and 400 mU X m-2 X min-1. Basal plasma tryptophan concentrations and LNAA levels were similar in young and old. Both tryptophan and LNAA levels decreased in an insulin dose-dependent manner (P less than .02). The dose-response effect of insulin on tryptophan levels in the elderly was less than in the young (P less than .03), while the response of the LNAA was similar in both age groups. The ratio of tryptophan to LNAA was less in the old when compared to the young (P less than .03) but increased in the two age groups in an insulin-dose-dependent fashion (P less than .02). Maximal plasma tryptophan decrements were 39% and 32%, and maximal LNAA declines were 58% and 61% in young and old, respectively, during the 400 mU X m-2 X min-1 studies.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3600282

Fukagawa, N K; Minaker, K L; Rowe, J W; Young, V R

1987-07-01

407

Metabolic heterogeneity of follicular amino acids in polycystic ovary syndrome is affected by obesity and related to pregnancy outcome  

PubMed Central

Background Polycystic ovary syndrome (PCOS) is a heterogeneous endocrine disorder frequently accompanied by obesity and by insulin resistance, and patients with this syndrome suffer from infertility and poor pregnancy outcome. Disturbances in plasma amino acid (AA) metabolism have been implicated in women with PCOS. However, direct evidence on follicular AA metabolic profiles in PCOS patients and their relationship with pregnancy outcome is sparse. Methods We conducted a prospective study in 63 PCOS patients and 48 controls in the Division of Reproductive Center, Peking University Third Hospital. Follicular AA levels were measured by the liquid chromatography-tandem mass spectrometric method, and the results were analyzed based on different grouping criteria. Results The levels of aromatic amino acid (AAA) increased in PCOS patients independent of obesity (P?amino acid (BCAA), glutamic acid, phenylalanine, alanine, and arginine increased with body mass index irrespective of the PCOS status (all P?valine and glutamic acid (all P?acid and serine levels were elevated in pregnant patients compared with the non-pregnant subjects (both P?valine were higher in the non-pregnant group than in the pregnant group (both P?

2014-01-01

408

Specific lysosomal transport of small neutral amino acids  

SciTech Connect

Studies of amino acid exodus from lysosomes have allowed us previously to describe transport systems specific for cystine and another for cationic amino acids in fibroblast lysosomes. They are now able to study amino acid uptake into highly purified fibroblast lysosomes obtained by separating crude granular fraction on gradients formed by centrifugation in 35% isoosmotic Percoll solutions. Analog inhibition and saturation studies indicate that L-(/sup 14/C)proline (50 ..mu..M) uptake by fibroblast lysosomes at 37/sup 0/C in 50 mM citrate/tris pH 7.0 buffer containing 0.25 M sucrose is mediated by two transport systems, one largely specific for L-proline and the other for which transport is shared with small neutral amino acids such as alanine, serine and threonine. At 7 mM, L-proline inhibits L-(/sup 14/C)proline uptake almost completely, whereas ala, ser, val, thr, gly, N-methylalanine and sarcosine inhibit proline uptake by 50-65%. The system shared by alanine, serine and threonine is further characterized by these amino acids strongly inhibiting the uptakes of each other. Lysosomal proline transport is selective for the L-isomer of the amino acid, and is scarcely inhibited by 7 mM arg, glu, asp, leu, phe, his, met, (methylamino) isobutyrate, betaine or N,N-dimethylglycine. Cis or trans-4-hydroxy-L-proline inhibit proline uptake only slightly. In sharp contrast to the fibroblast plasma membrane in which Na/sup +/ is required for most proline and alanine transport, lysosomal uptake of these amino acids occurs independently of Na/sup +/.

Pisoni, R.L.; Flickinger, K.S.; Thoene, J.G.; Christensen, H.N.

1986-05-01

409

An amino acid depleted cell-free protein synthesis system for the incorporation of non-canonical amino acid analogs into proteins.  

PubMed

Residue-specific incorporation of non-canonical amino acids into proteins is usually performed in vivo using amino acid auxotrophic strains and replacing the natural amino acid with an unnatural amino acid analog. Herein, we present an efficient amino acid depleted cell-free protein synthesis system that can be used to study residue-specific replacement of a natural amino acid by an unnatural amino acid analog. This system combines a simple methodology and high protein expression titers with a high-efficiency analog substitution into a target protein. To demonstrate the productivity and efficacy of a cell-free synthesis system for residue-specific incorporation of unnatural amino acids in vitro, we use this system to show that 5-fluorotryptophan and 6-fluorotryptophan substituted streptavidin retain the ability to bind biotin despite protein-wide replacement of a natural amino acid for the amino acid analog. We envisage this amino acid depleted cell-free synthesis system being an economical and convenient format for the high-throughput screening of a myriad of amino acid analogs with a variety of protein targets for the study and functional characterization of proteins substituted with unnatural amino acids when compared to the currently employed in vivo methodologies. PMID:24631721

Singh-Blom, Amrita; Hughes, Randall A; Ellington, Andrew D

2014-05-20

410

Availability of phenylisothiocyanate for the amino acid sequence/configuration determination of peptides containing D/L-amino acids.  

PubMed

A potential use for phenylisothiocyanate (PITC), the most popular Edman reagent, is presented for analysis of the amino acid sequence and configuration in peptides containing D/L-amino acids. After derivatization with PITC of the N-terminal amino acid (L-Tyr) of an enkephalin analogue, [D-Ala2, D-Leu5]-enkephalin, followed by cleavage/cyclization with trifluoroacetic acid at 50 degrees C for 5 min, the liberated 2-anilino-5-thiazolinone-L-Tyr (ATZ-L-Tyr) was further treated with 20% aqueous trifluoroacetic acid at 50 degrees C for 10 min. The resultant phenylthiohydantoin (PTH)-L-Tyr was then separated on a chiral stationary phase (a penylcarbamoylated cyclodextrin column), retaining its configuration. The residual sequence and configurations of the peptide (D-Ala-Gly-L-Phe-D-Leu) were also determined by separating the corresponding PTH-D- or L-amino acids on chiral columns. This method may be applicable to an automatic Edman sequence analyzer for the configuration determination of peptides containing D/L-amino acids. PMID:8520211

Imai, K; Matsunaga, H; Santa, T; Homma, H

1995-01-01

411

Boron-containing amino carboxylic acid compounds and uses thereof  

DOEpatents

Novel compounds which are useful for boron neutron capture therapy (BNCT) are disclosed. The compounds comprise a stable boron-containing group and an aminocycloalkane carboxylic acid group or a boronated acyclic hydrocarbon-linked amino carboxylic acid. Methods for synthesis of the compounds and for use of the compounds in BNCT are disclosed.

Kabalka, George W. (Knoxville, TN); Srivastava, Rajiv R. (Knoxville, TN)

2000-03-14

412

Peculiarities of electrostatic interactions between amino acids and salicylic acid in aqueous solution  

Microsoft Academic Search

Based on calorimetric data, the enthalpy of transfer of salicylic acid to aqueous buffer solutions with the addition of different\\u000a amino acids at the constant acidity of medium pH 7.35 was determined. It was shown that the exothermicity of transfer and\\u000a negative enthalpic coefficients for these pairwise interactions of salicylic acid with amino acids considerably increase with\\u000a increasing charge of

V. P. Barannikov; V. G. Badelin; M. B. Berezin

2009-01-01

413

Age related changes in blood-to-brain amino acid transport and incorporation into brain protein.  

PubMed

Blood-to-brain amino acid transport consists of at least two components: 1. a fast rate or early process, commonly measured by the intra-carotid bolus injection method and attributed to transport across the capillary endothelium and entry into the astrocytes, and, 2. a slow rate or later component measured over 2 to 15 minutes probably associated with exit from the astrocytes and entry into the neurons. Incorporation into brain protein is temporally related to the second process. In the present study the slow and fast rate transport components and the incorporation into brain protein of tyrosine (Tyr) and Valine (Val) was measured in young adult and aged male C57BL/6 mice. The results indicate that the fast rate transport component is unaffected by age while the rates of the slow process and protein turnover show an exponential decline most marked between 3 and 8 months of age. Changes in the relative incorporation of Tyr and Val suggest that brain protein metabolism is altered qualitatively as well as quantitatively in aging, in these animals. PMID:6856024

Samuels, S; Fish, I; Schwartz, S A; Hochgeschwender, U

1983-02-01

414

DNA binding mode of novel tetradentate amino acid based 2-hydroxybenzylidene-4-aminoantipyrine complexes  

NASA Astrophysics Data System (ADS)

Few transition metal complexes of tetradentate N2O2 donor Schiff base ligands containing 2-hydroxybenzylidene-4-aminoantipyrine and amino acids (alanine/valine) abbreviated to KHL1/KHL2 have been synthesized. All the metal complexes have been fully characterized with the help of elemental analyses, molecular weights, molar conductance values, magnetic moments and spectroscopic data. The Schiff bases KHL1/KHL2 are found to act as tetradentate ligands using N2O2 donor set of atoms leading to a square-planar geometry for the complexes around the metal ions. The binding behaviors of the complexes to calf thymus DNA have been investigated by absorption spectra, viscosity measurements and cyclic voltammetry. The DNA binding constants reveal that all these complexes interact with DNA through minor groove binding mode. The studies on mechanism of photocleavage reveal that singlet oxygen (1O2) and superoxide anion radical (O2rad -) may play an important role in the photocleavage. The Schiff bases and their metal complexes have been screened for their in vitro antibacterial activities against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus epidermidis, Klebsiella pneumoniae and antifungal activities against Aspergillus niger, Fusarium solani, Culvularia lunata, Rhizoctonia bataicola and Candida albicans by MIC method.

Raman, N.; Sobha, S.; Selvaganapathy, M.; Mahalakshmi, R.

2012-10-01

415

Expanding metabolism for total biosynthesis of the nonnatural amino acid L-homoalanine.  

PubMed

The dramatic increase in healthcare cost has become a significant burden to the world. Many patients are denied the accessibility of medication because of the high price of drugs. Total biosynthesis of chiral drug intermediates is an environmentally friendly approach that helps provide more affordable pharmaceuticals. Here we have expanded the natural metabolic capability to biosynthesize a nonnatural amino acid L-homoalanine, which is a chiral precursor of levetiracetam, brivaracetam, and ethambutol. We developed a selection strategy and altered the substrate specificity of ammonium-assimilating enzyme glutamate dehydrogenase. The specificity constant k(cat)/K(m) of the best mutant towards 2-ketobutyrate is 50-fold higher than that towards the natural substrate 2-ketoglutarate. Compared to transaminase IlvE and NADH-dependent valine dehydrogenases, the evolved glutamate dehydrogenase increased the conversion yield of 2-ketobutyrate to L-homoalanine by over 300% in aerobic condition. As a result of overexpressing the mutant glutamate dehydrogenase and Bacillus subtilis threonine dehydratase in a modified threonine-hyperproducing Escherichia coli strain (ATCC98082, DeltarhtA), 5.4 g/L L-homoalanine was produced from 30 g/L glucose (0.18 g/g glucose yield, 26% of the theoretical maximum). This work opens the possibility of total biosynthesis of other nonnatural chiral compounds that could be useful pharmaceutical intermediates. PMID:20332210

Zhang, Kechun; Li, Han; Cho, Kwang Myung; Liao, James C

2010-04-01

416

Expanding metabolism for total biosynthesis of the nonnatural amino acid L-homoalanine  

PubMed Central

The dramatic increase in healthcare cost has become a significant burden to the world. Many patients are denied the accessibility of medication because of the high price of drugs. Total biosynthesis of chiral drug intermediates is an environmentally friendly approach that helps provide more affordable pharmaceuticals. Here we have expanded the natural metabolic capability to biosynthesize a nonnatural amino acid L-homoalanine, which is a chiral precursor of levetiracetam, brivaracetam, and ethambutol. We developed a selection strategy and altered the substrate specificity of ammonium-assimilating enzyme glutamate dehydrogenase. The specificity constant kcat/Km of the best mutant towards 2-ketobutyrate is 50-fold higher than that towards the natural substrate 2-ketoglutarate. Compared to transaminase IlvE and NADH-dependent valine dehydrogenases, the evolved glutamate dehydrogenase increased the conversion yield of 2-ketobutyrate to L-homoalanine by over 300% in aerobic condition. As a result of overexpressing the mutant glutamate dehydrogenase and Bacillus subtilis threonine dehydratase in a modified threonine-hyperproducing Escherichia coli strain (ATCC98082, ?rhtA), 5.4 g/L L-homoalanine was produced from 30 g/L glucose (0.18 g/g glucose yield, 26% of the theoretical maximum). This work opens the possibility of total biosynthesis of other nonnatural chiral compounds that could be useful pharmaceutical intermediates. PMID:20332210

Zhang, Kechun; Li, Han; Cho, Kwang Myung; Liao, James C.

2010-01-01

417

Fungal Peptaibiotics: Assessing Potential Meteoritic Amino Acid Contamination  

NASA Technical Reports Server (NTRS)

The presence of non-protein alpha-dialkyl-amino acids such as alpha-aminoisobutyric acid (alpha-A1B) and isovaline (Iva), which are relatively rare in the terrestrial biosphere, has long been used as an indication of the indigeneity of meteoritic amino acids, however, the discovery of alpha-AIB in peptides producers by a widespread group of filamentous fungi indicates the possibility of a terrestrial biotic source for the alpha-AIB observed in some meteorites. The alpha-AIB-containing peptides produced by these fungi are dubbed peptaibiotics. We measured the molecular distribution and stable carbon and nitrogen isotopic ratios for amino acids found in the total hydrolysates of four biologically synthesized peptaibiotics. We compared these aneasurenetts with those from the CM2 carbonaceous chondrite Murchison and from three Antarctic CR2 carbonaceous chondrites in order to understand the peptaibiotics as a potential source of meteoritic contamination.

Elsila, J. E.; Callahan, M. P.; Glavin, D. P.; Dworkin, J. P.; Bruckner, H.

2010-01-01

418

Structure-based ligand discovery for the Large-neutral Amino Acid Transporter 1, LAT-1  

E-print Network

Structure-based ligand discovery for the Large-neutral Amino Acid Transporter 1, LAT-1 Ethan G) The Large-neutral Amino Acid Transporter 1 (LAT-1)--a sodium- independent exchanger of amino acids, thyroid, and placenta, where it mediates transport of large-neutral amino acids (e.g., tyrosine) and thyroid hormones (e

Sali, Andrej

419

AMINO ACIDS AND PROTEIN ADEQUACY FOR HONEY BEES OF POLLENS FROM DESERT PLANTS AND OTHER FLORAL  

E-print Network

AMINO ACIDS AND PROTEIN ADEQUACY FOR HONEY BEES OF POLLENS FROM DESERT PLANTS AND OTHER FLORAL from pollen primarily as a source of essential amino acids. Thus, we determined the amino acids, and proline were the predominant amino acids in all desert pollens examined. The desert plants had low protein

Paris-Sud XI, Université de

420

Periodic Distributions of Hydrophobic Amino Acids Allows the Definition of Fundamental Building Blocks  

E-print Network

Periodic Distributions of Hydrophobic Amino Acids Allows the Definition of Fundamental Building that hydrophobic amino acids are globally conserved even if they are subjected to high rate substitution. Statistical analysis of amino acids evolution within blocks of hydrophobic amino acids detected in sequences

Carbone, Alessandra