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1

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

Microsoft Academic Search

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

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

2009-01-01

2

Aromatic Amino Acid Requirement of the Lactating Sow  

Microsoft Academic Search

ABSTRACT Six mature,Yorkshire X Landrace,sows,were,randomly,assigned to a 6 X 6 Latin-square ex- periment,on d 5 of lactation to determine,the total phenylalanine,(Phe) and tyrosine (Tyr) require- ment. A control diet of corn sugar, cornstarch, whey, L-glutamic acid, solka floc, soybean oil, amino acids, minerals and vitamins was supplemented with L-Phe to provide .30 (basal), .45, .60, .75, .90 and 1.05% total

W. A. Leilis; V. C. Speer

2010-01-01

3

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 ...

4

Aromatic amino acid requirement of the lactating sow.  

PubMed

Six mature Yorkshire X Landrace sows were randomly assigned to a 6 X 6 Latin-square experiment on d 5 of lactation to determine the total phenylalanine (Phe) and tyrosine (Tyr) requirement. A control diet of corn sugar, cornstarch, whey, L-glutamic acid, solka floc, soybean oil, amino acids, minerals and vitamins was supplemented with L-Phe to provide .30 (basal), .45, .60, .75, .90 and 1.05% total aromatic amino acids (TAAA). Each diet was fed to a maximum of 5.5 kg/d within each of six 10-d periods. Feed intake, average pig weight gain and sow milk yield decreased linearly (P less than .01) with increasing period. Sow milk yield was maximized at .75% TAAA (quadratic, P less than .10), but average pig weight gain did not reflect the higher yield. Urea nitrogen decreased quadratically with increasing dietary Phe in both plasma (P less than .05) and urine (P less than .01) to a breakpoint at .56% TAAA. Plasma Phe increased (quadratic, P less than .01) as dietary TAAA increased, but no clear inflection point was obtained. A sharp rise (quadratic, P less than .001) in plasma Tyr occurred at .73% dietary TAAA. Plasma lysine decreased (linear, P less than .001) to a low level at .76% TAAA, but plasma methionine was unaffected by treatment. Urine allantoin/urea X protein intake was maximized at .61% TAAA (quadratic, P less than .01). Nitrogen (N) intake varied among diets (quadratic, P less than .05), but fecal N was not altered by TAAA level.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:4086394

Lellis, W A; Speer, V C

1985-12-01

5

Requirements for indispensable amino acids in adult humans: longer-term amino acid kinetic study with support for the adequacy of the Massachusetts Institute of Technology amino acid requirement pattern  

Microsoft Academic Search

Twenty young men received an L-amino acid diet, supplying 140 mg Nkgdand patterned as in the Egg diet for 1 wk, and then for 3 wk either a pattern based on inter- national recommendations (modified FAO diet; n = 7), our new amino acid requirement pattern (MIT diet; n 7), on the egg pattern (Egg diet; n = 6). At

J Sergio Marchini; Joaquin Cortiella; Takeyuki Hiramatsu; Thomas E Chapman; Vernon R Young

6

Can amino acid requirements for nutritional maintenance in adult humans be approximated from the amino acid composition of body mixed proteins?  

PubMed Central

The quantitative needs for the dietary indispensable amino acids in adult human protein nutrition are still poorly established. Tracer studies with 13C-labeled amino acids have been undertaken previously in our laboratories to reevaluate and further determine the minimum physiological needs for selected indispensable amino acids in healthy adult volunteers. For those amino acids that have not yet been studied by this approach we have proposed a tentative set of requirement figures based on considerations of the amino acid composition of body mixed proteins and the rate of obligatory amino acid losses (i.e., losses when the diet contains no proteins or amino acids). Here we provide an argument for, and a justification of, this approach as an interim measure until more comprehensive data become available on the quantitative aspects of amino acid metabolism in healthy humans.

Young, V R; el-Khoury, A E

1995-01-01

7

THE SPECIFIC AMINO ACID REQUIREMENTS OF A HUMAN CARCINOMA CELL (STRAIN HELA) IN TISSUE CULTURE  

PubMed Central

The amino acid requirements of a human uterine carcinoma cell (HeLa strain) have been defined. The 12 compounds previously found to be essential for the growth of a mouse fibroblast proved similarly essential for this human epithelial cell. They included arginine, cyst(e)ine, histidine, and tyrosine, in addition to the eight amino acids required for nitrogen balance in man (isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine). Only the L-amino acids were active; the D-enantiomorphs had no demonstrable effect at physiologic concentrations. The minimum concentrations required for survival and limited growth varied from 0.003 然 per ml. for L-tryptophan, to 0.1 然 per ml. for L-lysine. The concentrations permitting optimum growth similarly varied from 0.01 然 per ml. for tryptophan, to 0.1 然 per ml. for leucine, isoleucine, threonine, lysine, and valine. The latter optimum concentrations of the individual amino acids were closely correlated with their serum levels. With at least six of the amino acids, high concentrations, in the range 1 to 10 然 per ml., caused a definite growth inhibition. In the absence of a single essential amino acid, degenerative changes occurred in the cells, culminating in their death and dissolution. In the early stages, however, these degenerative changes could be reversed by the restoration of the missing component.

Eagle, Harry

1955-01-01

8

37 CFR 1.823 - Requirements for nucleotide and/or amino acid sequences as part of the application.  

Code of Federal Regulations, 2010 CFR

...Requirements for nucleotide and/or amino acid sequences as part of the application...Disclosures Containing Nucleotide And/or Amino Acid Sequences 禮 1.823 Requirements for nucleotide and/or amino acid sequences as part of the application....

2010-07-01

9

37 CFR 1.823 - Requirements for nucleotide and/or amino acid sequences as part of the application.  

Code of Federal Regulations, 2010 CFR

...Requirements for nucleotide and/or amino acid sequences as part of the application...Disclosures Containing Nucleotide And/or Amino Acid Sequences 禮 1.823 Requirements for nucleotide and/or amino acid sequences as part of the application....

2009-07-01

10

Amino acid, heme, and sterol requirements of the nematode, Rhabditis maupasi.  

PubMed

Rhabditis maupasi, a nematode that occurs in the mantle cavity of Helix aspersa and related North African food snails, requires 5 amino acids (lysine, methionine, phenylalanine, tryptophane and valine) for maintenance of the stage-3 survival larvae, and 5 additional amino acids (arginine, isoleucine, leucine, threonine and, marginally, histidine) for development of these larvae into adults and for reproduction. Tyrosine is beneficial but not absolutely required for reproduction. These results were obtained with axenic R. maupasi grown in a chemically defined medium containing salts, trace metals, purines and pyrimidines, Krebs cycle intermediates, a fatty acid (butyric), vitamins, urea, and a carbohydrate (dextrose). The complete medium contained 18 amino acids; each of 18 test media was deficient in one of the amino acids. In the complete medium and in a medium lacking the "nematode nonessential" amino acids, stage-3 R. maupasi developed into adults and produced one generation of offspring. For continuous cultivation, however, the nematode also required hemin or another iron porphyrin as well as a sterol such as cholesterol. PMID:569194

Brockelman, C R; Jackson, G J

1978-10-01

11

Amino Acids  

NSDL National Science Digital Library

The Featured Molecules this month are the 20 standard α-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.

12

Surgical Stress Resistance Induced by Single Amino Acid Deprivation Requires Gcn2 in Mice  

PubMed Central

Dietary restriction, or reduced food intake without malnutrition, increases life span, health span, and acute stress resistance in model organisms from yeast to nonhuman primates. Although dietary restriction is beneficial for human health, this treatment is not widely used in the clinic. Here, we show that short-term, ad libitum feeding of diets lacking essential nutrients increased resistance to surgical stress in a mouse model of ischemia reperfusion injury. Dietary preconditioning by 6 to 14 days of total protein deprivation, or removal of the single essential amino acid tryptophan, protected against renal and hepatic ischemic injury, resulting in reduced inflammation and preserved organ function. Pharmacological treatment with halofuginone, which activated the amino acid starvation response within 3 days by mimicking proline deprivation, was also beneficial. Both dietary and pharmacological interventions required the amino acid sensor and eIF2? (eukaryotic translation initiation factor 2?) kinase Gcn2 (general control nonderepressible 2), implicating the amino acid starvation response and translational control in stress protection. Thus, short-term dietary or pharmacological interventions that modulate amino acid sensing can confer stress resistance in models of surgical ischemia reperfusion injury.

Peng, Wei; Robertson, Lauren; Gallinetti, Jordan; Mejia, Pedro; Vose, Sarah; Charlip, Allison; Chu, Timothy; Mitchell, James R.

2012-01-01

13

77 FR 65537 - Requirements for Patent Applications Containing Nucleotide Sequence and/or Amino Acid Sequence...  

Federal Register 2010, 2011, 2012, 2013

...Applications Containing Nucleotide Sequence and/or Amino Acid Sequence Disclosures ACTION: Proposed collection; comment...Patent applications that contain nucleotide and/or amino acid sequence disclosures must include a copy of the...

2012-10-29

14

Decreased amino acid requirements of growing chicks due to immunologic stress.  

PubMed

Experiments were conducted to determine the influence of immunologic stress on methionine and lysine requirements of growing chicks. Immunologic stress was elicited by injection of either Escherichia coli lipopolysaccharide or heat-killed Staphylococcus aureus every other day for 6 d. In the first experiment, diets were formulated to provide methionine levels of 0.30, 0.50 and 0.70%. In the second experiment, diets contained 0.75, 0.90 or 1.2% lysine. In chicks fed amino acid-sufficient diets, those chicks injected with immunogens had slower growth, lower feed intake and poorer efficiency of feed utilization than those injected with saline. The decreases due to immunogens were diminished in chicks fed amino acid-deficient diets. The methionine requirements of saline- and immunogen-injected chicks were above 0.5% and between 0.3 and 0.5%, respectively; the lysine requirements were greater than 0.95% and between 0.7 and 0.95%, respectively. Thus immunogen injection decreased methionine and lysine requirements, probably because of a decreased need of amino acids for growth and tissue accretion. Immunogen-induced depression in serum zinc and increase in serum copper levels were ameliorated by lysine or methionine deficiencies. Compared with saline-injected chicks, immunogen-injected chicks had significantly higher serum interleukin-1 (IL-1) activity by 53% when fed the methionine-sufficient diet, but they did not have significantly greater IL-1 levels when fed the methionine-deficient diet. These observations indicate that the diminished expression of immunologic stress in amino acid-deficient chicks is due to an impaired immune response. PMID:2458441

Klasing, K C; Barnes, D M

1988-09-01

15

Studies on the protein and sulfur amino acid requirements of young bobwhite quail  

USGS Publications Warehouse

Four experiments were conducted with purified diets to examine the influence of protein level and to estimate the sulfur amino acid (S.A.A.) requirement of young Bobwhite quail (Colinus virginianus). These studies demonstrated (I) that 26% protein was sufficient for rapid growth when the diet was supplemented with methionine; (2) that diets containing higher levels of protein (29.3% and 31.3%) failed to support satisfactory growth unless they contained supplemental methionine; and (3) that young Bobwhite quail require no more than 1.0% sulfur-containing amino acids for optimal growth and efficiency of feed utilization. A fifth experiment was conducted to examine the protein and S.A.A. requirements of young Bobwhite quail using practical rations and to compare results with those obtained with purified diets. Diets containing 24%, 26% and 28% protein were supplied with and without supplemental methionine in a five week study. Results showed significant growth responses to protein and supplemental methionine. Responses showed that Bobwhite quail require no more than 26% protein for maximum growth and efficiency of feed utilization when the S.A.A. level of the diet was approximately 1.0%. The results were in close agreement with those obtained with purified diets. These findings define more precisely than had been known the quantitative requirements of young Bobwhite quail for protein and for the S.A.A. necessary for optimal growth.

Serafin, J.A.

1977-01-01

16

Plasma amino acids  

MedlinePLUS

Plasma amino acids is a screening test done on infants that looks at the amounts of amino ... Rheumatoid arthritis High or low concentrations of individual plasma amino acids must be interpreted along with other ...

17

Determination of the amino acid requirements for a protein hinge in triosephosphate isomerase.  

PubMed Central

We have determined the sequence requirements for a protein hinge in triosephosphate isomerase. The codons encoding the hinge at the C-terminus of the active-site lid of triosephosphate isomerase were replaced with a genetic library of all possible 8,000 amino acid combinations. The most active of these 8,000 mutants were selected using in vivo complementation of a triosephosphate isomerase deficient strain of E. coli, DF502. Approximately 3% of the mutants complement DF502 with an activity that is above 70% of wild-type activity. The sequences of these hinge mutants reveal that the solutions to the hinge flexibility problem are varied. Moreover, these preferences are sequence dependent; that is, certain pairs occur frequently. They fall into six families of similar sequences. In addition to the hinge sequences expected on the basis of phylogenetic analysis, we selected three new families of 3-amino-acid hinges: X(A/S)(L/K/M), X(aromatic/beta-branched)(L/K), and XP(S/N). The absence of these hinge families in the more than 60 known species of triosephosphate isomerase suggests that during evolution, not all of sequence space is sampled, perhaps because there is no neutral mutation pathway to access the other families.

Sun, J.; Sampson, N. S.

1998-01-01

18

ATF2 is required for amino acid-regulated transcription by orchestrating specific histone acetylation  

Microsoft Academic Search

The transcriptional activation of CHOP (a CCAAT\\/ enhancer-binding protein-related gene) by amino acid deprivation involves the activating transcrip- tion factor 2 (ATF2) and the activating transcription factor 4 (ATF4) binding the amino acid response element (AARE) within the promoter. Using a chromatin immunoprecipitation approach, we report that in vivo binding of phospho-ATF2 and ATF4 to CHOP AARE are associated with

Alain Bruhat; Yoan Cherasse; Anne-Catherine Maurin; Wolfgang Breitwieser; Laurent Parry; Christiane Deval; Nic Jones; C. Jousse; P. Fafournoux

2007-01-01

19

Dietary requirements of synthesizable amino acids by animals: a paradigm shift in protein nutrition  

PubMed Central

Amino acids are building blocks for proteins in all animals. Based on growth or nitrogen balance, amino acids were traditionally classified as nutritionally essential or nonessential for mammals, birds and fish. It was assumed that all the nutritionally nonessential amino acids (NEAA) were synthesized sufficiently in the body to meet the needs for maximal growth and optimal health. However, careful analysis of the scientific literature reveals that over the past century there has not been compelling experimental evidence to support this assumption. NEAA (e.g., glutamine, glutamate, proline, glycine and arginine) play important roles in regulating gene expression, cell signaling, antioxidative responses, fertility, neurotransmission, and immunity. Additionally, glutamate, glutamine and aspartate are major metabolic fuels for the small intestine to maintain its digestive function and to protect the integrity of the intestinal mucosa. Thus, diets for animals must contain all NEAA to optimize their survival, growth, development, reproduction, and health. Furthermore, NEAA should be taken into consideration in revising the ideal protein concept that is currently used to formulate swine and poultry diets. Adequate provision of all amino acids (including NEAA) in diets enhances the efficiency of animal production. In this regard, amino acids should not be classified as nutritionally essential or nonessential in animal or human nutrition. The new Texas A&M Universitys optimal ratios of dietary amino acids for swine and chickens are expected to beneficially reduce dietary protein content and improve the efficiency of their nutrient utilization, growth, and production performance.

2014-01-01

20

Dietary requirements of synthesizable amino acids by animals: a paradigm shift in protein nutrition.  

PubMed

Amino acids are building blocks for proteins in all animals. Based on growth or nitrogen balance, amino acids were traditionally classified as nutritionally essential or nonessential for mammals, birds and fish. It was assumed that all the "nutritionally nonessential amino acids (NEAA)" were synthesized sufficiently in the body to meet the needs for maximal growth and optimal health. However, careful analysis of the scientific literature reveals that over the past century there has not been compelling experimental evidence to support this assumption. NEAA (e.g., glutamine, glutamate, proline, glycine and arginine) play important roles in regulating gene expression, cell signaling, antioxidative responses, fertility, neurotransmission, and immunity. Additionally, glutamate, glutamine and aspartate are major metabolic fuels for the small intestine to maintain its digestive function and to protect the integrity of the intestinal mucosa. Thus, diets for animals must contain all NEAA to optimize their survival, growth, development, reproduction, and health. Furthermore, NEAA should be taken into consideration in revising the "ideal protein" concept that is currently used to formulate swine and poultry diets. Adequate provision of all amino acids (including NEAA) in diets enhances the efficiency of animal production. In this regard, amino acids should not be classified as nutritionally essential or nonessential in animal or human nutrition. The new Texas A&M University's optimal ratios of dietary amino acids for swine and chickens are expected to beneficially reduce dietary protein content and improve the efficiency of their nutrient utilization, growth, and production performance. PMID:24999386

Wu, Guoyao

2014-01-01

21

Rapid degradation of auxin/indoleacetic acid proteins requires conserved amino acids of domain II and is proteasome dependent.  

PubMed

Auxin rapidly induces auxin/indoleacetic acid (Aux/IAA) transcription. The proteins encoded are short-lived nucleus-localized transcriptional regulators that share four conserved domains. In a transient assay measuring protein accumulation, an Aux/IAA 13-amino acid domain II consensus sequence was sufficient to target firefly luciferase (LUC) for low protein accumulation equivalent to that observed previously for full-length PSIAA6. Single amino acid substitutions in these 13 amino acids, corresponding to known auxin response mutants, resulted in a sixfold to 20-fold increase in protein accumulation. Naturally occurring variant amino acids had no effect. Residues identified as essential by single alanine substitutions were not sufficient when all flanking amino acids were alanine, indicating the importance of flanking regions. Using direct protein degradation measurements in transgenic Arabidopsis seedlings, full-length IAA1, PSIAA6, and the N-terminal 73 PSIAA6 amino acids targeted LUC for rapid degradation with 8-min half-lives. The C-terminal 109 amino acids did not affect LUC half-life. Smaller regions containing domain II also targeted LUC for rapid degradation, but the rates were not equivalent to those of the full-length protein. A single domain II substitution in the context of full-length PSIAA6 increased half-life 30-fold. Proteasome inhibitors affected Aux/IAA::LUC fusion protein accumulation, demonstrating the involvement of the proteasome. PMID:11595806

Ramos, J A; Zenser, N; Leyser, O; Callis, J

2001-10-01

22

of natural amino acids  

Microsoft Academic Search

A new method for the synthesis of protected N a -(-Y-alkyl) amino acids (Y is a thio, amino or carboxy group) and related compounds by reductive alkylation of natural amino acids is reported. These new amino acids serve as building units for the synthesis of backbone-cyclic peptides. They are orthogonally protected at the -amino position by butoxycarbonyl (Boc) or 9-fluorenylmethoxycarbonyl

Gal Bitan; Dan Muller; Ron Kasher; Evgenia V. Gluhov; Chaim Gilon

1997-01-01

23

Mms Sensitivity of All Amino Acid-Requiring Mutants in Aspergillus and Its Suppression by Mutations in a Single Gene  

PubMed Central

All available amino acid-requiring mutants of Aspergillus nidulans were found to be hypersensitive to MMS (methyl methanesulfonate) to various degrees. On MMS media, secondary mutations could be selected which suppress this MMS sensitivity but do not affect the requirement. Many such mutations were analyzed and found to be alleles of one gene, smsA (= suppressor of MMS sensitivity), which mapped distal on the right arm of chromosome V. This gene is more likely to be involved in general regulation of amino acid biosynthesis than MMS uptake, since a variety of pathway interactions were clearly modified by smsA suppressors in the absence of MMS.

Kafer, Etta

1987-01-01

24

The components required for amino acid neurotransmitter signaling are present in adipose tissues  

Microsoft Academic Search

The adipocyte does not only serve as fuel stor- age but produces and secretes compounds with modulating effects on food intake and energy homeostasis. Although there is firm evidence for a centrally mediated regulation of adipocyte function via the autonomous nervous system, little is known about signaling between adipocytes. Amino acid neurotransmitters are candidates for such paracrine signaling. Here, we

Anne Nicolaysen; Runhild Gammelsaeter; Jon Storm-Mathisen; Vidar Gundersen; Per Ole Iversen

2007-01-01

25

Pyrolysis products from amino acids and protein: Highest mutagenicity requires cytochrome P1-450  

PubMed Central

Pyrolysis products of proteins and amino acids are highly mutagenic, but metabolism of these chemicals by rat liver subcellular fractions is known to be required for production of the mutagenic intermediates. We examined the mutagenesis of seven purified pyrolysis products from tryptophan, lysine, glutamic acid, and soybean globulin with Salmonella typhimurium strain TA98 in the presence of liver fractions from genetically responsive C57BL/6N and Ahb/Ahd or nonresponsive DBA/2N and Ahd/Ahd mice that had been pretreated in vivo with benzo[a]pyrene. For all pyrolysis products tested, mutagenesis is 2-fold to more than 1000-fold greater with C57BL/6N and Ahb/Ahd than with DBA/2N or Ahd/Ahd liver fractions. A sucrose density gradient assay for detecting the Ah regulatory gene product, the receptor, was studied with C57BL/6N hepatic cytosol. At levels 100 times in excess of [1,6-3H]2,3,7,8-tetrachlorodibenzo-p-dioxin, nonlabeled 2,3,7,8-tetrachlorodibenzo-p-dioxin, 3-methylcholanthrene, and ?-naphthoflavone (inducers of cytochrome P1-450) are able to displace the radioligand from its hepatic cytosolic receptor; four pyrolysates from tryptophan, glutamic acid, and soybean globulin did not have this capacity. These data indicate that the pyrolysis products tested, although not effective as inducers of cytochrome P1-450, are most mutagenic when metabolized by P1-450. Potent P1-450 inducerspresent in pyrolysates during the combustion processmight be present in quantities insufficient to initiate mutagenesis or carcinogenesis but might have a synergistic action, or act as comutagens or cocarcinogens, with the N-containing heterocyclic pyrolysis products. A quantitative relationship between mutagenic and carcinogenic potency of these pyrolysis products remains, however, to be demonstrated.

Nebert, Daniel W.; Bigelow, Sanford W.; Okey, Allan B.; Yahagi, Takie; Mori, Yuko; Nagao, Minako; Sugimura, Takashi

1979-01-01

26

Requirement for lysosomal localization of mTOR for its activation differs between leucine and other amino acids.  

PubMed

The mammalian target of rapamycin complex 1 (mTORC1) is a master regulator of cell growth and metabolism. It controls many cell functions by integrating nutrient availability and growth factor signals. Amino acids, and in particular leucine, are among the main positive regulators of mTORC1 signaling. The current model for the regulation of mTORC1 by amino acids involves the movement of mTOR to the lysosome mediated by the Rag-GTPases. Here, we have examined the control of mTORC1 signaling and mTOR localization by amino acids and leucine in serum-fed cells, because both serum growth factors (or, e.g., insulin) and amino acids are required for full activation of mTORC1 signaling. We demonstrate that mTORC1 activity does not closely correlate with the lysosomal localization of mTOR. In particular, leucine controls mTORC1 activity without any detectable modification of the lysosomal localization of mTOR, indicating that the signal(s) exerted by leucine is likely distinct from those exerted by other amino acids. In addition, knock-down of the Rag-GTPases attenuated the inhibitory effect of amino acid- or leucine-starvation on the phosphorylation of mTORC1 targets. Furthermore, data from cells where Rag expression has been knocked down revealed that leucine can promote mTORC1 signaling independently of the lysosomal localization of mTOR. Our data complement existing models for the regulation of mTORC1 by amino acids and provide new insights into this important topic. PMID:24793303

Averous, Julien; Lambert-Langlais, Sarah; Carraro, Val廨ie; Gourbeyre, Oph幨ie; Parry, Laurent; B'Chir, Wafa; Muranishi, Yuki; Jousse, C幨ine; Bruhat, Alain; Maurin, Anne-Catherine; Proud, Christopher G; Fafournoux, Pierre

2014-09-01

27

Amino acid analysis  

NASA Technical Reports Server (NTRS)

The process and apparatus for qualitative and quantitative analysis of the amino acid content of a biological sample are presented. The sample is deposited on a cation exchange resin and then is washed with suitable solvents. The amino acids and various cations and organic material with a basic function remain on the resin. The resin is eluted with an acid eluant, and the eluate containing the amino acids is transferred to a reaction vessel where the eluant is removed. Final analysis of the purified acylated amino acid esters is accomplished by gas-liquid chromatographic techniques.

Winitz, M.; Graff, J. (inventors)

1974-01-01

28

Amino acids in carbonaceous chondrites.  

PubMed

For almost 20 years laboratory experiments have advanced the concepts of chemical evolution, particularly with regard to formation of the amino acids. What has been generally lacking is concrete natural evidence for this chemical evolution hypothesis. The recent development of sophisticated analytical techniques and availability of carbonaceous chondrites with a minimum of terrestrial contamination has resulted in the identification of amino acids which provide strong evidence for a natural extraterrestrial chemical synthesis. Since the initial find in the Murchison meteorite (a type II carbonaceous chondrite) of both protein and nonprotein amino acids with nearly equal abundances of D and L isomers, further studies have been carried out. These studies have revealed the presence of at least 35 amino acids; the population consists of a wide variety of linear, cyclic and polyfunctional amino acids which shows a trend of decreasing concentration with increasing carbon number. Investigations of the Murray meteorite (a type II carbonaceous chondrite) has produced similar results, but studies of the Orgueil meteorite (a type I carbonaceous chondrite) show only a limited suite of amino acids, some of which appear to be indigenous while others appear to be terrestrial contaminanats. A sample of the Murchison meteorite was extracted with D2O and in addition of 'free' amino acids, showing no deuterium incorporation, some amino acids showed the presence of deuterium suggesting either a 'precursor(s)' or hydrogen-deuterium exchange which require(s) formation of carbon-hydrogen bonds. PMID:1153189

Lawless, J G; Peterson, E

1975-01-01

29

Amino acid requirements of springbok ( Antidorcas marsupialis), blesbok ( Damaliscus dorcas phillipsi) and impala ( Aepyceros melampus) estimated by the whole empty body essential amino acid profile  

Microsoft Academic Search

The essential amino acid (EAA) profile of the duodenal digesta and whole empty body of springbok (Antidorcas marsupialis), blesbok (Damaliscus dorcas phillipsi) and impala (Aepyceros melampus) were investigated. Significant differences were found between the whole empty body EAA composition of the three game species, whether protein quantity was taken into account (g AA\\/100g crude protein (CP)) or not (expressed as

L. van Zyl; A. V. Ferreira

2003-01-01

30

Autophagy in Trypanosoma brucei: Amino Acid Requirement and Regulation during Different Growth Phases  

PubMed Central

Autophagy in the protozoan parasite, Trypanosoma brucei, may be involved in differentiation between different life cycle forms and during growth in culture. We have generated multiple parasite cell lines stably expressing green fluorescent protein- or hemagglutinin-tagged forms of the autophagy marker proteins, TbAtg8.1 and TbAtg8.2, in T. brucei procyclic forms to establish a trypanosome system for quick and reliable determination of autophagy under different culture conditions using flow cytometry. We found that starvation-induced autophagy in T. brucei can be inhibited by addition of a single amino acid, histidine, to the incubation buffer. In addition, we show that autophagy is induced when parasites enter stationary growth phase in culture and that their capacity to undergo starvation-induced autophagy decreases with increasing cell density.

Schmidt, Remo S.; Butikofer, Peter

2014-01-01

31

Specific amino acid (L-arginine) requirement for the microbiostatic activity of murine macrophages.  

PubMed Central

The microbiostatic action of macrophages was studied in vitro employing peritoneal cytotoxic macrophages (CM) from mice acting against Cryptococcus neoformans cultured in Dulbecco's medium with 10% dialyzed fetal bovine serum. Fungistasis was measured using electronic particle counting after lysis of macrophages with detergent. Macrophage fungistasis failed in medium lacking only L-arginine. Complete fungistasis was restored by L-arginine; restoration was concentration dependent, maximal at 200 microM. Deletion of all other essential amino acids did not abrogate fungistasis provided that L-arginine was present. Of twenty guanido compounds, including D-arginine, only three (L-arginine, L-homoarginine, and L-arginine methylester) supported fungistasis. Known activators or mediators of macrophage cytotoxicity (endotoxin, interferon gamma, tumor necrosis factor) did not replace L-arginine for CM-mediated fungistasis. The guanido analogue NG-monomethyl-L-arginine was a potent competitive inhibitor of CM-mediated fungistasis giving 50% inhibition at an inhibitor/L-arginine ratio of 1:27. Although CM completely blocked fungal reproduction via an L-arginine-dependent mechanism, the majority of the dormant fungi remained viable. Thus, this mechanism is viewed as a microbiostatic process similar or identical to the tumoristatic effect of macrophages. This suggests the production of a broad spectrum biostatic metabolite(s) upon consumption of L-arginine by cytotoxic macrophages.

Granger, D L; Hibbs, J B; Perfect, J R; Durack, D T

1988-01-01

32

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

33

Amino Acid Signaling in Saccharomyces cerevisiae: a Permease-Like Sensor of External Amino Acids and F-Box Protein Grr1p Are Required for Transcriptional Induction of the AGP1 Gene, Which Encodes a Broad-Specificity Amino Acid Permease  

PubMed Central

The SSY1 gene of Saccharomyces cerevisiae encodes a member of a large family of amino acid permeases. Compared to the 17 other proteins of this family, however, Ssy1p displays unusual structural features reminiscent of those distinguishing the Snf3p and Rgt2p glucose sensors from the other proteins of the sugar transporter family. We show here that SSY1 is required for transcriptional induction, in response to multiple amino acids, of the AGP1 gene encoding a low-affinity, broad-specificity amino acid permease. Total noninduction of the AGP1 gene in the ssy1? mutant is not due to impaired incorporation of inducing amino acids. Conversely, AGP1 is strongly induced by tryptophan in a mutant strain largely deficient in tryptophan uptake, but it remains unexpressed in a mutant that accumulates high levels of tryptophan endogenously. Induction of AGP1 requires Uga35p(Dal81p/DurLp), a transcription factor of the Cys6-Zn2 family previously shown to participate in several nitrogen induction pathways. Induction of AGP1 by amino acids also requires Grr1p, the F-box protein of the SCFGrr1 ubiquitin-protein ligase complex also required for transduction of the glucose signal generated by the Snf3p and Rgt2p glucose sensors. Systematic analysis of amino acid permease genes showed that Ssy1p is involved in transcriptional induction of at least five genes in addition to AGP1. Our results show that the amino acid permease homologue Ssy1p is a sensor of external amino acids, coupling availability of amino acids to transcriptional events. The essential role of Grr1p in this amino acid signaling pathway lends further support to the hypothesis that this protein participates in integrating nutrient availability with the cell cycle.

Iraqui, Ismail; Vissers, Stephan; Bernard, Florent; de Craene, Johan-Owen; Boles, Eckhard; Urrestarazu, Antonio; Andre, Bruno

1999-01-01

34

Protein turnover, amino acid requirements and recommendations for athletes and active populations.  

PubMed

Skeletal muscle is the major deposit of protein molecules. As for any cell or tissue, total muscle protein reflects a dynamic turnover between net protein synthesis and degradation. Noninvasive and invasive techniques have been applied to determine amino acid catabolism and muscle protein building at rest, during exercise and during the recovery period after a single experiment or training sessions. Stable isotopic tracers ((13)C-lysine, (15)N-glycine, 淡5-phenylalanine) and arteriovenous differences have been used in studies of skeletal muscle and collagen tissues under resting and exercise conditions. There are different fractional synthesis rates in skeletal muscle and tendon tissues, but there is no major difference between collagen and myofibrillar protein synthesis. Strenuous exercise provokes increased proteolysis and decreased protein synthesis, the opposite occurring during the recovery period. Individuals who exercise respond differently when resistance and endurance types of contractions are compared. Endurance exercise induces a greater oxidative capacity (enzymes) compared to resistance exercise, which induces fiber hypertrophy (myofibrils). Nitrogen balance (difference between protein intake and protein degradation) for athletes is usually balanced when the intake of protein reaches 1.2 g kg(-1) day(-1) compared to 0.8 g kg(-1) day(-1) in resting individuals. Muscular activities promote a cascade of signals leading to the stimulation of eukaryotic initiation of myofibrillar protein synthesis. As suggested in several publications, a bolus of 15-20 g protein (from skimmed milk or whey proteins) and carbohydrate ( 30 g maltodextrine) drinks is needed immediately after stopping exercise to stimulate muscle protein and tendon collagen turnover within 1 h. PMID:22666780

Poortmans, J R; Carpentier, A; Pereira-Lancha, L O; Lancha, A

2012-10-01

35

Protein turnover, amino acid requirements and recommendations for athletes and active populations  

PubMed Central

Skeletal muscle is the major deposit of protein molecules. As for any cell or tissue, total muscle protein reflects a dynamic turnover between net protein synthesis and degradation. Noninvasive and invasive techniques have been applied to determine amino acid catabolism and muscle protein building at rest, during exercise and during the recovery period after a single experiment or training sessions. Stable isotopic tracers (13C-lysine, 15N-glycine, 2H5-phenylalanine) and arteriovenous differences have been used in studies of skeletal muscle and collagen tissues under resting and exercise conditions. There are different fractional synthesis rates in skeletal muscle and tendon tissues, but there is no major difference between collagen and myofibrillar protein synthesis. Strenuous exercise provokes increased proteolysis and decreased protein synthesis, the opposite occurring during the recovery period. Individuals who exercise respond differently when resistance and endurance types of contractions are compared. Endurance exercise induces a greater oxidative capacity (enzymes) compared to resistance exercise, which induces fiber hypertrophy (myofibrils). Nitrogen balance (difference between protein intake and protein degradation) for athletes is usually balanced when the intake of protein reaches 1.2?g搔g?1搞ay?1 compared to 0.8?g搔g?1搞ay?1 in resting individuals. Muscular activities promote a cascade of signals leading to the stimulation of eukaryotic initiation of myofibrillar protein synthesis. As suggested in several publications, a bolus of 15-20?g protein (from skimmed milk or whey proteins) and carbohydrate ( 30?g maltodextrine) drinks is needed immediately after stopping exercise to stimulate muscle protein and tendon collagen turnover within 1?h.

Poortmans, J.R.; Carpentier, A.; Pereira-Lancha, L.O.; Lancha, A.

2012-01-01

36

Amino acid metabolism in ruminants  

Microsoft Academic Search

All animals require amino acids (AA) which are the building blocks of proteins required for optimal growth, reproduction, lactation, and maintenance. In ruminants, proteins and AA are first subject to microbial degradation in the rumen making it difficult to predict the quality and quantity of AA that are absorbed by the animal. In ruminants, absorbed AA comes from microbial protein

Limin Kung; Lyle M. Rode

1996-01-01

37

TOR Signaling is Required for Amino Acid Stimulation of Early Trypsin Protein Synthesis in the Midgut of Aedes aegypti Mosquitoes  

PubMed Central

Blood meal digestion in mosquitoes occurs in two phases, an early phase that is translationally-regulated, and a late phase that is transcriptionally-regulated. Early trypsin is a well-characterized serine endoprotease that is representative of other early phase proteases in the midgut that are only synthesized after feeding. Since the kinase Target of Rapamycin (TOR) has been implicated as a nutrient sensor in other systems, including the mosquito fat body, we tested if TOR signaling is involved in early trypsin protein synthesis in the mosquito midgut in response to feeding. We found that ingestion of an amino acid meal by female mosquitoes induces early trypsin protein synthesis, coincident with phosphorylation of two known TOR target proteins, p70S6 kinase (S6K) and the translational repressor 4E-Binding Protein (4E-BP). Moreover, in vitro culturing of midguts from unfed mosquitoes led to amino acid-dependent phosphorylation of S6K and 4E-BP which could be blocked by treatment with rapamycin, a TOR-specific inhibitor. Lastly, by injecting mosquitoes with TOR double stranded RNA (dsRNA) or rapamycin, we demonstrated that TOR signaling was required in vivo for both phosphorylation of S6K and 4E-BP in the midgut, and for translation of early trypsin mRNA in response to amino acid feeding. It may be possible to target the TOR signaling pathway in the midgut to inhibit blood meal digestion, and thereby, decrease fecundity and the spread of mosquito-borne diseases.

Brandon, Michelle C.; Pennington, James E.; Isoe, Jun; Zamora, Jorge; Schillinger, Anne-Sophie; Miesfeld, Roger L.

2008-01-01

38

A Single Amino Acid Change in the Newcastle Disease Virus Fusion Protein Alters the Requirement for HN Protein in Fusion  

PubMed Central

The role of a leucine heptad repeat motif between amino acids 268 and 289 in the structure and function of the Newcastle disease virus (NDV) F protein was explored by introducing single point mutations into the F gene cDNA. The mutations affected either folding of the protein or the fusion activity of the protein. Two mutations, L275A and L282A, likely interfered with folding of the molecule since these proteins were not proteolytically cleaved, were minimally expressed at the cell surface, and formed aggregates. L268A mutant protein was cleaved and expressed at the cell surface although the protein migrated slightly slower than wild type on polyacrylamide gels, suggesting an alteration in conformation or processing. L268A protein was fusion inactive in the presence or absence of HN protein expression. Mutant L289A protein was expressed at the cell surface and proteolytically cleaved at better than wild-type levels. Most importantly, this protein mediated syncytium formation in the absence of HN protein expression although HN protein enhanced fusion activity. These results show that a single amino acid change in the F1 portion of the NDV F protein can alter the stringent requirement for HN protein expression in syncytium formation.

Sergel, Theresa A.; McGinnes, Lori W.; Morrison, Trudy G.

2000-01-01

39

A single amino acid change in the Newcastle disease virus fusion protein alters the requirement for HN protein in fusion.  

PubMed

The role of a leucine heptad repeat motif between amino acids 268 and 289 in the structure and function of the Newcastle disease virus (NDV) F protein was explored by introducing single point mutations into the F gene cDNA. The mutations affected either folding of the protein or the fusion activity of the protein. Two mutations, L275A and L282A, likely interfered with folding of the molecule since these proteins were not proteolytically cleaved, were minimally expressed at the cell surface, and formed aggregates. L268A mutant protein was cleaved and expressed at the cell surface although the protein migrated slightly slower than wild type on polyacrylamide gels, suggesting an alteration in conformation or processing. L268A protein was fusion inactive in the presence or absence of HN protein expression. Mutant L289A protein was expressed at the cell surface and proteolytically cleaved at better than wild-type levels. Most importantly, this protein mediated syncytium formation in the absence of HN protein expression although HN protein enhanced fusion activity. These results show that a single amino acid change in the F(1) portion of the NDV F protein can alter the stringent requirement for HN protein expression in syncytium formation. PMID:10799584

Sergel, T A; McGinnes, L W; Morrison, T G

2000-06-01

40

Branched-Chain Amino Acids Are Required for the Survival and Virulence of Actinobacillus pleuropneumoniae in Swine?  

PubMed Central

In Actinobacillus pleuropneumoniae, which causes porcine pleuropneumonia, ilvI was identified as an in vivo-induced (ivi) gene and encodes the enzyme acetohydroxyacid synthase (AHAS) required for branched-chain amino acid (BCAA) biosynthesis. ilvI and 7 of 32 additional ivi promoters were upregulated in vitro when grown in chemically defined medium (CDM) lacking BCAA. Based on these observations, we hypothesized that BCAA would be found at limiting concentrations in pulmonary secretions and that A. pleuropneumoniae mutants unable to synthesize BCAA would be attenuated in a porcine infection model. Quantitation of free amino acids in porcine pulmonary epithelial lining fluid showed concentrations of BCAA ranging from 8 to 30 ?mol/liter, which is 10 to 17% of the concentration in plasma. The expression of both ilvI and lrp, a global regulator that is required for ilvI expression, was strongly upregulated in CDM containing concentrations of BCAA similar to those found in pulmonary secretions. Deletion-disruption mutants of ilvI and lrp were both auxotrophic for BCAA in CDM and attenuated compared to wild-type A. pleuropneumoniae in competitive index experiments in a pig infection model. Wild-type A. pleuropneumoniae grew in CDM+BCAA but not in CDM?BCAA in the presence of sulfonylurea AHAS inhibitors. These results clearly demonstrate that BCAA availability is limited in the lungs and support the hypothesis that A. pleuropneumoniae, and potentially other pulmonary pathogens, uses limitation of BCAA as a cue to regulate the expression of genes required for survival and virulence. These results further suggest a potential role for AHAS inhibitors as antimicrobial agents against pulmonary pathogens.

Subashchandrabose, Sargurunathan; LeVeque, Rhiannon M.; Wagner, Trevor K.; Kirkwood, Roy N.; Kiupel, Matti; Mulks, Martha H.

2009-01-01

41

Amino acid analysis.  

PubMed

Amino acid analysis (AAA) is one of the best methods to quantify peptides and proteins. Two general approaches to quantitative AAA exist, namely, classical postcolumn derivatization following ion-exchange chromatography and precolumn derivatization followed by reversed-phase HPLC (RP-HPLC). Excellent instrumentation and several specific methodologies are available for both approaches, and both have advantages and disadvantages. This unit focuses on picomole-level AAA of peptides and proteins using the most popular precolumn-derivatization method, namely, phenylthiocarbamyl amino acid analysis (PTC-AAA). It is directed primarily toward those interested in establishing the technology with a modest budget. PTC derivatization and analysis conditions are described, and support and alternate protocols describe additional techniques necessary or useful for most any AAA method--e.g., sample preparation, hydrolysis, instrument calibration, data interpretation, and analysis of difficult or unusual residues such as cysteine, tryptophan, phosphoamino acids, and hydroxyproline. PMID:18429107

Crabb, J W; West, K A; Dodson, W S; Hulmes, J D

2001-05-01

42

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

43

Inorganic Polyphosphate Kinase in Required to Stimulate Protein Degradation and for Adaptation to Amino Acid Starvation in Escherichia coli  

Microsoft Academic Search

Inorganic polyphosphate (polyP) kinase was studied for its roles in physiological responses to nutritional deprivation in Escherichia coli. A mutant lacking polyP kinase exhibited an extended lag phase of growth, when shifted from a rich to a minimal medium (nutritional downshift). Supplementation of amino acids to the minimal medium abolished the extended growth lag of the mutant. Levels of the

Akio Kuroda; Shoutaro Tanaka; Tsukasa Ikeda; Junichi Kato; Noboru Takiguchi; Hisao Ohtake

1999-01-01

44

Amino acids in Arctic aerosols  

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

45

Amino acids in Arctic aerosols  

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

46

Perceived Cost of Auxotrophic Amino Acids in Two Bacterial Species  

Microsoft Academic Search

Amino acid biosynthetic pathways are highly conserved throughout all domains of life. Biosynthesis of amino acid requires the diversion of resources from energy production to amino acid production. The consequent energy-cost of producing an individual amino acid is can be estimated by addingthe amount of ATP expended in production itself to the amount of potential energy lost. Some organisms lack

Esley M. Heizer Jr; D. W. Raiford; M. L. Raymer; D. E. Krane

2009-01-01

47

Piezoelectricity in protein amino acids  

NASA Astrophysics Data System (ADS)

The piezoelectric activity of protein amino acids and their compounds has been measured using the pulse method at a frequency of 10 MHz. It has been established that, at room temperature, the piezoelectric effect is not observed in ?-glycine (achiral amino acid) and protein amino acids of the L modification, namely, methionine, phenylalanine, and tryptophan. An assumption has been made that this phenomenon is associated with the enhanced damping of elastic vibrations excited in samples due to the piezoelectric effect.

Lemanov, V. V.; Popov, S. N.; Pankova, G. A.

2011-06-01

48

Regulation of L-amino acid oxidase and of D-amino acid oxidase in Neurospora crassa  

Microsoft Academic Search

Neurospora crassa possesses an inducible L-amino acid oxidase that is expressed only when cells are derepressed for nitrogen in the presence of an amino acid. Enzyme synthesis requires both induction by an amino acid and simultaneous nitrogen catabolite derepression. Carbon limition in the presence of an amino acid does not permit induction of L-amino acid oxidase. The nit-2 gene is

Len Sikora; George A. Marzluf

1982-01-01

49

Region and amino acid residues required for Rad51C binding in the human Xrcc3 protein  

Microsoft Academic Search

The Xrcc3 protein, which is required for the homo- logous recombinational repair of damaged DNA, forms a complex with the Rad51C protein in human cells. Mutations in either the Xrcc3 or Rad51C gene cause extreme sensitivity to DNA-damaging agents and generate the genomic instability frequently found in tumors. In the present study, we found that the Xrcc3 segment containing amino

Hitoshi Kurumizaka; Rima Enomoto; Maki Nakada; Keiko Ed; Shigeyuki Yokoyama; Takehiko Shibata

2003-01-01

50

Identification of Amino Acid Residues Required for the Substrate Specificity of Human and Mouse Chondroitin Sulfate Hydrolase (Conventional Hyaluronidase-4)*  

PubMed Central

Human hyaluronidase-4 (hHYAL4), a member of the hyaluronidase family, has no hyaluronidase activity, but is a chondroitin sulfate (CS)-specific endo-?-N-acetylgalactosaminidase. The expression of hHYAL4 is not ubiquitous but restricted to placenta, skeletal muscle, and testis, suggesting that hHYAL4 is not involved in the systemic catabolism of CS, but rather has specific functions in particular organs or tissues. To elucidate the function of hyaluronidase-4 in vivo, mouse hyaluronidase-4 (mHyal4) was characterized. mHyal4 was also demonstrated to be a CS-specific endo-?-N-acetylgalactosaminidase. However, mHyal4 and hHYAL4 differed in the sulfate groups they recognized. Although hHYAL4 strongly preferred GlcUA(2-O-sulfate)-GalNAc(6-O-sulfate)-containing sequences typical in CS-D, where GlcUA represents d-glucuronic acid, mHyal4 depolymerized various CS isoforms to a similar extent, suggesting broad substrate specificity. To identify the amino acid residues responsible for this difference, a series of human/mouse HYAL4 chimeric proteins and HYAL4 point mutants were generated, and their preference for substrates was investigated. A combination of the amino acid residues at 261265 and glutamine at 305 was demonstrated to be essential for the enzymatic activity as well as substrate specificity of mHyal4.

Kaneiwa, Tomoyuki; Miyazaki, Anzu; Kogawa, Ryo; Mizumoto, Shuji; Sugahara, Kazuyuki; Yamada, Shuhei

2012-01-01

51

Parasite sulphur amino acid metabolism  

Microsoft Academic Search

This paper reviews current knowledge regarding the metabolism of the sulphur-containing amino acids methionine and cysteine in parasitic protozoa and helminths. Particular emphasis is placed on the unusual aspects of parasite biochemistry which may present targets for rational design of anti-parasite drugs. In general, the basic pathways of sulphur amino acid metabolism in most parasites resemble those of their mammalian

John Walker; John Barrett

1997-01-01

52

Modification of fetal plasma amino acid composition by placental amino acid exchangers in vitro  

PubMed Central

Fetal growth is dependent on both the quantity and relative composition of amino acids delivered to the fetal circulation, and impaired placental amino acid supply is associated with restricted fetal growth. Amino acid exchangers can alter the composition, but not the quantity, of amino acids in the intra- and extracellular amino acid pools. In the placenta, exchangers may be important determinants of the amino acid composition in the fetal circulation. This study investigates the substrate specificity of exchange between the placenta and the feto-placental circulation. Maternalfetal transfer of radiolabelled amino acids and creatinine were measured in the isolated perfused human placental cotyledon. Transfer of l-[14C]serine or l-[14C]leucine, and [3H]glycine, were measured in the absence of amino acids in the fetal circulation (transfer by non-exchange mechanisms) and following 1020 ?mol boluses of unlabelled amino acids into the fetal circulation to provide substrates for exchange (transfer by exchange and non-exchange mechanisms). The ability of fetal arterial boluses of l-alanine and l-leucine to stimulate release of amino acids from the placenta was also determined using HPLC in order to demonstrate the overall pattern of amino acid release. Experiments with radiolabelled amino acids demonstrated increased maternalfetal transfer of l-serine and l-leucine, but not glycine, following boluses of specific amino acids into the fetal circulation. l-[14C]Leucine, but not l-[14C]serine or [3H]glycine, was transferred from the maternal to the fetal circulation by non-exchange mechanisms also (P < 0.01). HPLC analysis demonstrated that fetal amino acid boluses stimulated increased transport of a range of different amino acids by 47 ?mol l?1 (P < 0.05). Amino acid exchange provides a mechanism to supply the fetus with amino acids that it requires for fetal growth. This study demonstrates that these transporters have the capacity to exchange micromolar amounts of specific amino acids, and suggests that they play an important role in regulating fetal plasma amino acid composition.

Cleal, Jane K; Brownbill, Paul; Godfrey, Keith M; Jackson, John M; Jackson, Alan A; Sibley, Colin P; Hanson, Mark A; Lewis, Rohan M

2007-01-01

53

Examination of lysine requirement of healthy young male adults on a Chinese habitual diet by the modified indicator amino acid oxidation method  

PubMed Central

There is currently no reference for intake of lysine for Chinese people; therefore, the present study was conducted to determine the lysine requirement of Chinese young male adults on a habitual Chinese mixed diet based on the modified indicator amino acid oxidation method. Seven young men with a mean age of 23.7 2.2 years that were healthy based on questionnaire, physical examinations and screening tests were evaluated. Subjects were evaluated over five consecutive 7 day periods, during which time they were administered decreasing amounts of lysine via the diet (65, 55, 45, 35, 25 mg搔g-1搞-1). Subjects were allowed to adapt from day 1 to 6 and the isotopes were measured on day 7 in each period. The subjects' body weights, body compositions and plasma proteins were also examined during the study. Amino acid kinetics were measured based on the indicator amino acid oxidation technique using the 13CO2 release rate and phenylalanine oxidation rate to estimate lysine requirements. Body weights, body compositions, and plasma proteins of subjects did not change significantly relative to those at baseline. The mean and the upper 95% CI of lysine requirements of Chinese habitual diets were determined to be 58.41 and 70.09 mg搔g-1搞-1, respectively, based on the 13CO2 release rate and 54.28 and 65.14 mg搔g-1搞-1, respectively, based on the phenylalanine oxidation rate.

Peng, Jing; Chen, Yu; Gong, Junjun; Xu, Huiqing

2014-01-01

54

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

55

Amino Acid Detection in Cometary Matter?  

NASA Astrophysics Data System (ADS)

The recent identification of amino acid structures in interstellar ice analogues [1, 2] strongly supports the assumption that amino acids are abundant in cometary matter too. Cometary matter is assumed to be built up of aggregates of interstellar dust particles. Amino acids are the molecular building blocks of proteins in living organisms. These results amplified the scientific interest in the ESA cometary mission Rosetta. The Rosetta Lander includes the Cosac experiment dedicated to the identification of chiral organic molecules in cometary matter itshape in situ \\upshape by multi column gas chromatography coupled with a reflectron time-of-flight mass spectrometer. However, the envisaged itshape in situ \\upshape amino acid analysis on the cometary surface requires special technical emphasis of the COSAC instrumentation. The context in which the amino acid identification in cometary matter is of interest will be outlined and the analytical solutions that make amino acids accessible to the COSAC instrument will be presented. A succesful identification of amino acid structures in cometary matter would help to understand the beginnings of the biomolecular evolution and the origin of the biomolecular asymmetry. [1] G.M. Mu隳z Caro, U.J. Meierhenrich, W.A. Schutte, B. Barbier, A. Arcones Sergovia, H. Rosenbauer, W.H.-P. Thiemann, A. Brack, J.M. Greenberg: itshape Nature \\upshape 416 (2002), 403-406. [2] M.P. Bernstein, J.P. Dworkin, S.A. Sandford, G.W. Cooper, L.J. Allamandola: itshape Nature \\upshape 416 (2002), 401-403.

Meierhenrich, U. J.; Munoz Caro, G. M.; Thiemann, W.; Goesmann, F.; Rosenbauer, H.

2003-04-01

56

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

57

Amino acid transport in podocytes.  

PubMed

It has recently been shown that formation of podocyte foot processes is dependent on a constant source of lipids and proteins (Simons M, Saffrich R, Reiser J, and Mundel P. J Am Soc Nephrol 10: 1633-1639, 1999). Here we characterize amino acid transport mechanisms in differentiated cultured podocytes and investigate whether it may be disturbed during podocyte injury. RT-PCR studies detected mRNA for transporters of neutral amino acids (ASCT1, ASCT2, and B(0/+)), cationic AA (CAT1 and CAT3), and anionic AA (EAAT2 and EAAT3). Alanine (Ala), asparagine, cysteine (Cys), glutamine (Gln), glycine (Gly), leucine (Leu), methionine (Met), phenylalanine (Phe), proline (Pro), serine (Ser), threonine (Thr), glutamic acid (Glu), arginine (Arg), and histidine (His) depolarized podocytes and increased their whole cell conductances. Depletion of extracellular Na(+) completely inhibited the depolarization induced by Ala, Gln, Glu, Gly, Leu, and Pro and decreased the depolarization induced by Arg and His, indicating the presence of Na(+)-dependent amino acid transport. Incubation of podocytes with 100 microg/ml puromycin aminonucleoside for 24 h significantly attenuated the effects induced by the various amino acids by approximately 70%. The data indicate the existence of different amino acid transporter systems in podocytes. Alteration of amino acid transport may participate in podocyte injury and disturbed foot process formation. PMID:10836988

Gloy, J; Reitinger, S; Fischer, K G; Schreiber, R; Boucherot, A; Kunzelmann, K; Mundel, P; Pavenst輐t, H

2000-06-01

58

Amino acid requirements for MDA5 and LGP2 recognition by paramyxovirus V proteins: a single arginine distinguishes MDA5 from RIG-I.  

PubMed

Paramyxovirus V proteins bind to MDA5 (melanoma differentiation-associated gene 5) and LGP2 (laboratory of genetics and physiology gene 2) but not RIG-I (retinoic acid-inducible gene I). The results demonstrate MDA5 R806 is essential for inhibition by diverse V proteins. Complementary substitution for the analogous RIG-I L714 confers V protein recognition. The analogous LGP2 R455 is required for recognition by measles V protein, but not other V proteins. These findings indicate that paramyxoviruses use a single amino acid to distinguish MDA5 from RIG-I and have evolved distinct contact sites for LGP2 interference. PMID:23269789

Rodriguez, Kenny R; Horvath, Curt M

2013-03-01

59

Amino Acid Requirements for MDA5 and LGP2 Recognition by Paramyxovirus V Proteins: a Single Arginine Distinguishes MDA5 from RIG-I  

PubMed Central

Paramyxovirus V proteins bind to MDA5 (melanoma differentiation-associated gene 5) and LGP2 (laboratory of genetics and physiology gene 2) but not RIG-I (retinoic acid-inducible gene I). The results demonstrate MDA5 R806 is essential for inhibition by diverse V proteins. Complementary substitution for the analogous RIG-I L714 confers V protein recognition. The analogous LGP2 R455 is required for recognition by measles V protein, but not other V proteins. These findings indicate that paramyxoviruses use a single amino acid to distinguish MDA5 from RIG-I and have evolved distinct contact sites for LGP2 interference.

Rodriguez, Kenny R.

2013-01-01

60

Endothelial cell spreading on fibrin requires fibrinopeptide B cleavage and amino acid residues 15-42 of the beta chain.  

PubMed Central

Adhesion and spreading of cultured human umbilical vein endothelial cells on fibrin surfaces of varying structure were characterized to understand better the interactions occurring between endothelium and fibrin at sites of vascular injury. Fibrin prepared with reptilase, which cleaves only fibrinopeptide A from fibrinogen, and fibrin prepared with thrombin, which cleaves both fibrinopeptide A and fibrinopeptide B, equally supported endothelial cell adhesion. In contrast, only fibrin made with thrombin mediated endothelial cell spreading, as assessed by fluorescence microscopy of cells stained with rhodamine phalloidin to identify actin stress fibers or by scanning electron microscopy. Fibrin prepared with reptilase failed to support cell spreading. To further investigate the role of the amino terminus of the fibrin beta chain after fibrinopeptide B cleavage in promoting cell spreading, protease III from Crotalus atrox venom was used to specifically cleave the amino-terminal 42 residues of the fibrinogen B beta chain. After clotting with thrombin, this fibrin derivative lacking B beta 1-42 failed to support significant cell spreading. Spreading on fibrin was unaffected by depletion of Weibel-Palade bodies from endothelial cells, indicating that the spreading was independent of stimulated von Willebrand factor release. We conclude that endothelial cell spreading on fibrin requires fibrinopeptide B cleavage and involves residues 15-42 of the fibrin beta chain. Images

Bunce, L A; Sporn, L A; Francis, C W

1992-01-01

61

BranchedChain Amino Acids  

Microsoft Academic Search

The branched-chain amino acids (BCAAs) leucine, isoleucine, and valine are synthesized by bacteria,\\u000a fungi, and plants, but are essential for vertebrates including humans, who must receive them from their\\u000a diet. The interest to construct overproducing industrial strains therefore stems from the need to supplement\\u000a the food or feed with these amino acids to use them in medical treatment and as

Miroslav P嫢ek

62

Amino Acids and the Mitochondria  

Microsoft Academic Search

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

Nicola King

63

D-amino acids trigger biofilm disassembly.  

PubMed

Bacteria form communities known as biofilms, which disassemble over time. In our studies outlined here, we found that, before biofilm disassembly, Bacillus subtilis produced a factor that prevented biofilm formation and could break down existing biofilms. The factor was shown to be a mixture of D-leucine, D-methionine, D-tyrosine, and D-tryptophan that could act at nanomolar concentrations. D-amino acid treatment caused the release of amyloid fibers that linked cells in the biofilm together. Mutants able to form biofilms in the presence of D-amino acids contained alterations in a protein (YqxM) required for the formation and anchoring of the fibers to the cell. D-amino acids also prevented biofilm formation by Staphylococcus aureus and Pseudomonas aeruginosa. D-amino acids are produced by many bacteria and, thus, may be a widespread signal for biofilm disassembly. PMID:20431016

Kolodkin-Gal, Ilana; Romero, Diego; Cao, Shugeng; Clardy, Jon; Kolter, Roberto; Losick, Richard

2010-04-30

64

Design and Characterization of Auxotrophy-Based Amino Acid Biosensors  

Microsoft Academic Search

Efficient and inexpensive methods are required for the high-throughput quantification of amino acids in physiological fluids or microbial cell cultures. Here we develop an array of Escherichia coli biosensors to sensitively quantify eleven different amino acids. By using online databases, genes involved in amino acid biosynthesis were identified that upon deletion should render the corresponding mutant auxotrophic for

Felix Bertels; Holger Merker; Christian Kost

2012-01-01

65

Amino Acid Sequence Requirements in the Hinge of Human Immunoglobulin A1 (IgA1) for Cleavage by Streptococcal IgA1 Proteases  

PubMed Central

The amino acid sequence requirements in the hinge of human immunoglobulin A1 (IgA1) for cleavage by IgA1 proteases of different species of Streptococcus were investigated. Recombinant IgA1 antibodies were generated with point mutations at proline 227 and threonine 228, the residues lying on either side of the peptide bond at which all streptococcal IgA1 proteases cleave wild-type human IgA1. The amino acid substitutions produced no major effect upon the structure of the mutant IgA1 antibodies or their functional ability to bind to Fc? receptors. However, the substitutions had a substantial effect upon sensitivity to cleavage with some streptococcal IgA1 proteases, with, in some cases, a single point mutation rendering the antibody resistant to a particular IgA1 protease. This effect was least marked with the IgA1 protease from Streptococcus pneumoniae, which showed no absolute requirement for either proline or threonine at residues 227 to 228. By contrast, the IgA1 proteases of Streptococcus oralis, Streptococcus sanguis, and Streptococcus mitis had an absolute requirement for proline at 227 but not for threonine at 228, which could be replaced by valine. There was evidence in S. mitis that proteases from different strains may have different amino acid requirements for cleavage. Remarkably, some streptococcal proteases appeared able to cleave the hinge at a distant alternative site if substitution prevented efficient cleavage of the original site. Hence, this study has identified key residues required for the recognition of the IgA1 hinge as a substrate by streptococcal IgA1 proteases, and it marks a preliminary step towards development of specific enzyme inhibitors.

Batten, Margaret R.; Senior, Bernard W.; Kilian, Mogens; Woof, Jenny M.

2003-01-01

66

Studying amino acid transport using liposomes.  

PubMed

The transport of amino acid across the membranes has great importance in cell metabolism. Specific experimental methodologies are required for measuring the vectorial reactions catalyzed by the membrane transporters. So far, the most widely used technique to study amino acid transport was the measure of amino acid flux in intact cell systems expressing a specific transporter. Some limitations in this procedure are caused by the presence of endogenous transporters and intracellular enzymes and by the inaccessibility of the intracellular compartment. Alternative experimental strategies which allow to reducing the interferences and improving the handling of the internal compartment would be useful to the amino acid transport knowledge.An experimental protocol, which makes use of liposomes to study the transport of amino acid mediated by the glutamine/amino acid (ASCT2) transporter, solubilized from rat kidney brush borders, is described. The procedure is based on the reconstitution of the transporter in liposomes by removal of detergent from mixed micelles of detergent, solubilized protein, and phospholipid. The transport is assayed in the formed proteoliposomes measuring the Na(+) dependent uptake of L: -[(3)H]glutamine in antiport with internal L: -glutamine. This method allows measuring the transport activity under well controlled experimental conditions and permits performing experiments which cannot be realized in intact cell systems. PMID:20013389

Indiveri, Cesare

2010-01-01

67

Bacterial ABC transporters of amino acids  

Microsoft Academic Search

There are two subfamilies of ABC uptake systems for amino acids in bacteria, the polar amino acid transport family and the hydrophobic amino acid transport family. We consider the general properties of these families and we examine the specific transporters. Focusing on some of the best-studied ATP binding cassette transporters we also examine the mechanism of amino acid uptake, paying

Arthur H. F. Hosie; Philip S. Poole

2001-01-01

68

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

69

Amino acid transport in Lactobacillus helveticus  

Microsoft Academic Search

Amino acid transport in Lactobacillus helveticus was analyzed. Strain specificity of amino acid transport was speculated between L. helveticus NCDO2712 and SBT2171. Glucose energized L. helveticus NCDO2712 actively transported and accumulated the essential and growth stimulating amino acids (leucine, isoleucine, valine, threonine, lysine, aspartic acid, glutamic acid, tyrosine, arginine, and histidine). Uptake of proline, phenylalanine and tryptophan was not observed.

Hadjime Nakajima; Edmund R. S. Kunji; Bert Poolman; Wil N. Konings

1998-01-01

70

mTORC1 senses lysosomal amino acids through an inside-out mechanism that requires the vacuolar H(+)-ATPase.  

PubMed

The mTOR complex 1 (mTORC1) protein kinase is a master growth regulator that is stimulated by amino acids. Amino acids activate the Rag guanosine triphosphatases (GTPases), which promote the translocation of mTORC1 to the lysosomal surface, the site of mTORC1 activation. We found that the vacuolar H(+)-adenosine triphosphatase ATPase (v-ATPase) is necessary for amino acids to activate mTORC1. The v-ATPase engages in extensive amino acid-sensitive interactions with the Ragulator, a scaffolding complex that anchors the Rag GTPases to the lysosome. In a cell-free system, ATP hydrolysis by the v-ATPase was necessary for amino acids to regulate the v-ATPase-Ragulator interaction and promote mTORC1 translocation. Results obtained in vitro and in human cells suggest that amino acid signaling begins within the lysosomal lumen. These results identify the v-ATPase as a component of the mTOR pathway and delineate a lysosome-associated machinery for amino acid sensing. PMID:22053050

Zoncu, Roberto; Bar-Peled, Liron; Efeyan, Alejo; Wang, Shuyu; Sancak, Yasemin; Sabatini, David M

2011-11-01

71

Signalling by amino acid nutrients.  

PubMed

It is clear that mTORC1 (mammalian target of rapamycin complex 1) is regulated by the presence of ambient amino acid nutrients. However, the mechanism by which amino acids regulate mTORC1 is still open to question, despite extensive efforts. Our recent work has revealed that PR61?, a B56 family regulatory subunit of PP2A (protein phosphatase 2A), associates with and regulates the activity of MAP4K3 (mitogen-activated protein kinase kinase kinase kinase 3), a protein kinase regulated by amino acid sufficiency that acts upstream of mTORC1. In searching for a physiological process regulated by amino acids, we have demonstrated recently that arginine plays a role in the activation of LPS (lipopolysaccharide)-induced MEK [MAPK (mitogen-activated protein kinase)/ERK (extracellular-signal-regulated kinase) kinase]/ERK signalling in macrophages. PP2A similarly associates with the upstream regulator of MEK in this signalling pathway, TPL-2 (tumour progression locus-2), in response to arginine availability. Thus PP2A is a negative regulator of both MAP4K3 and TPL-2 in both mTORC1 and MEK/ERK signalling pathways. PMID:21428916

Yan, Lijun; Lamb, Richard F

2011-04-01

72

Biosynthesis of natural products containing ?-amino acids.  

PubMed

Covering: up to January, 2014We focus here on ?-amino acids as components of complex natural products because the presence of ?-amino acids produces structural diversity in natural products and provides characteristic architectures beyond those of ordinary ?-l-amino acids, thus generating significant and unique biological functions in nature. In this review, we first survey the known bioactive ?-amino acid-containing natural products including nonribosomal peptides, macrolactam polyketides, and nucleoside-?-amino acid hybrids. Next, the biosynthetic enzymes that form ?-amino acids from ?-amino acids and the denovo synthesis of ?-amino acids are summarized. Then, the mechanisms of ?-amino acid incorporation into natural products are reviewed. Because it is anticipated that the rational swapping of the ?-amino acid moieties with various side chains and stereochemistries by biosynthetic engineering should lead to the creation of novel architectures and bioactive compounds, the accumulation of knowledge regarding ?-amino acid-containing natural product biosynthetic machinery could have a significant impact in this field. In addition, genome mining of characteristic ?-amino acid biosynthetic genes and unique ?-amino acid incorporation machinery could lead to the discovery of new ?-amino acid-containing natural products. PMID:24926851

Kudo, Fumitaka; Miyanaga, Akimasa; Eguchi, Tadashi

2014-07-01

73

The Ubiquitin E3 Ligase LOSS OF GDU2 Is Required for GLUTAMINE DUMPER1-Induced Amino Acid Secretion in Arabidopsis1[C][W][OA  

PubMed Central

Amino acids serve as transport forms for organic nitrogen in the plant, and multiple transport steps are involved in cellular import and export. While the nature of the export mechanism is unknown, overexpression of GLUTAMINE DUMPER1 (GDU1) in Arabidopsis (Arabidopsis thaliana) led to increased amino acid export. To gain insight into GDU1s role, we searched for ethyl-methanesulfonate suppressor mutants and performed yeast-two-hybrid screens. Both methods uncovered the same gene, LOSS OF GDU2 (LOG2), which encodes a RING-type E3 ubiquitin ligase. The interaction between LOG2 and GDU1 was confirmed by glutathione S-transferase pull-down, in vitro ubiquitination, and in planta coimmunoprecipitation experiments. Confocal microscopy and subcellular fractionation indicated that LOG2 and GDU1 both localized to membranes and were enriched at the plasma membrane. LOG2 expression overlapped with GDU1 in the xylem and phloem tissues of Arabidopsis. The GDU1 protein encoded by the previously characterized intragenic suppressor mutant log1-1, with an arginine in place of a conserved glycine, failed to interact in the multiple assays, suggesting that the Gdu1D phenotype requires the interaction of GDU1 with LOG2. This hypothesis was supported by suppression of the Gdu1D phenotype after reduction of LOG2 expression using either artificial microRNAs or a LOG2 T-DNA insertion. Altogether, in accordance with the emerging bulk of data showing membrane protein regulation via ubiquitination, these data suggest that the interaction of GDU1 and the ubiquitin ligase LOG2 plays a significant role in the regulation of amino acid export from plant cells.

Pratelli, Rejane; Guerra, Damian D.; Yu, Shi; Wogulis, Mark; Kraft, Edward; Frommer, Wolf B.; Callis, Judy; Pilot, Guillaume

2012-01-01

74

Arrangement of domains, and amino acid residues required for binding of vascular cell adhesion molecule-1 to its counter-receptor VLA-4 (alpha 4 beta 1)  

PubMed Central

Interaction of the vascular cell adhesion molecule (VCAM-1) with its counter-receptor very late antigen-4 (VLA-4) (integrin alpha 4 beta 1) is important for a number of developmental pathways and inflammatory functions. We are investigating the molecular mechanism of this binding, in the interest of developing new anti-inflammatory drugs that block it. In a previous report, we showed that the predominant form of VCAM-1 on stimulated endothelial cells, seven-domain VCAM (VCAM-7D), is a functionally bivalent molecule. One binding site requires the first and the other requires the homologous immunoglobulin-like domain. Rotary shadowing and electron microscopy of recombinant soluble VCAM-7D molecules suggests that the seven Ig-like domains are extended in a slightly bent linear array, rather than compactly folded together. We have systematically mutagenized the first domain of VCAM-6D (a monovalent, alternately spliced version mission domain 4) by replacing 3-4 amino acids of the VCAM sequence with corresponding portions of the related ICAM-1 molecule. Specific amino acids, important for binding VLA-4 include aspartate 40 (D40), which corresponds to the acidic ICAM- 1 residue glutamate 34 (E34) previously reported to be essential for binding of ICAM-1 to its integrin counter-receptor LFA-1. A small region of VCAM including D40, QIDS, can be replaced by the similar ICAM- 1 sequence, GIET, without affecting function or epitopes, indicating that this region is part of a general integrin-binding structure rather than a determinant of binding specificity for a particular integrin. The VCAM-1 sequence G65NEH also appears to be involved in binding VLA-4.

1994-01-01

75

When and why amino acids?  

PubMed Central

This article reviews especially the early history of glutamate and GABA as neurotransmitters in vertebrates. The proposal that some amino acids could mediate synaptic transmission in the CNS initially met with much resistance. Both GABA and its parent glutamate are abundant in the brain; but, unlike glutamate, GABA had no obvious metabolic function. By the late 1950s, the switch of interest from electrical to chemical transmission invigorated the search for central transmitters. Its identification with Factor I, a brain extract that inhibited crustacean muscle, focused interest on GABA as a possible inhibitory transmitter. In the first microiontophoretic tests, though GABA strongly inhibited spinal neurons, these effects were considered non-specific. Strong excitation by glutamate (and other acidic amino acids) led to the same conclusion. However, their great potency and rapid actions on cortical neurons convinced other authors that these endogenous amino acids are probably synaptic transmitters. This was partly confirmed by showing that both IPSPs and GABA greatly increased Cl? conductance, their effects having similar reversal potentials. Many anticonvulsants proving to be GABA antagonists, by the 1970s GABA became widely accepted as a mediator of IPSPs. Progress was much slower for glutamate. Being generated on distant dendrites, EPSPs could not be easily compared with glutamate-induced excitation, and the search for specific antagonists was long hampered by the lack of blockers and the variety of glutamate receptors. These difficulties were gradually overcome by the application of powerful techniques, such as single channel recording, cloning receptors, as well as new pharmacological tools.

Krnjevic, Kresimir

2010-01-01

76

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.

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

1971-01-01

77

Amino Acid Metabolism in Uremia of Man.  

National Technical Information Service (NTIS)

The following studies on various facets of amino acid disposition and metabolism in uremic patients were carried out: (a) Assessment of the losses of amino acids during hemodialysis with the Kiil Dialyzer and the Hollow Fiber Artificial Kidney. (b) Examin...

J. H. Peters, P. F. Gulyassy

1971-01-01

78

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

79

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

80

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

81

Biochemistry and biotechnology of amino acid dehydrogenases  

Microsoft Academic Search

Over the last decade, amino acid dehydrogenases such as alanine dehydrogenase (Ala DH), leucine dehydrogenase (Leu DH), and phenylalanine dehydrogenase (Phe DH) have been applied to the enantiomer-specific synthesis and analysis of various amino acids. In perticular, amino acid dehydrogenases from thermophiles have received much attention because of their high stability. Their productivity was enhanced and the purification facilitated by

Toshihisa Ohshima; Kenji Soda

82

Amino acids as regulators of gene expression  

Microsoft Academic Search

The role of amino acids as substrates for protein synthesis is well documented. However, a function for amino acids in modulating the signal transduction pathways that regulate mRNA translation has only recently been described. Interesting, some of the signaling pathways regulated by amino acids overlap with those classically associated with the cellular response to hormones such as insulin and insulin-like

Scot R Kimball; Leonard S Jefferson

2004-01-01

83

Evolutionarily Conserved Optimization of Amino Acid Biosynthesis  

Microsoft Academic Search

The cognate bias hypothesis states that early 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 of the enzymes comprising a particular amino acid biosynthetic\\u000a pathway is predicted to confer a selective growth advantage on cells.

Ethan O. Perlstein; Benjamin L. de Bivort; Samuel Kunes; Stuart L. Schreiber

2007-01-01

84

An alternative model of amino acid replacement  

Microsoft Academic Search

Motivation: The observed correlations between pairs of homologous protein sequences are typically explained in terms of a Markovian dynamic of amino acid substitution. This model assumes that every location on the protein sequence has the same background distribution of amino acids, an assumption that is incompatible with the observed heterogeneity of protein amino acid profiles and with the success of

Gavin E. Crooksand; Steven E. Brenner

2005-01-01

85

Sulfur-Containing Amino Acid Metabolism in Parasitic Protozoa  

Microsoft Academic Search

Sulfur-containing amino acids play indispensable roles in a wide variety of biological activities including protein synthesis, methylation, and biosynthesis of polyamines and glutathione. Biosynthesis and catabolism of these amino acids need to be carefully regulated to achieve the requirement of the above-mentioned activities and also to eliminate toxicity attributable to the amino acids. Genome-wide analyses of enzymes involved in the

Tomoyoshi Nozaki; Vahab Ali; Masaharu Tokoro

2005-01-01

86

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... 禮 721.1643 Benzenesulfonic acid, amino substituted phenylazo-. ...generically as a benzenesulfonic acid, amino substituted phenylazo-...

2013-07-01

87

Bacterial synthesis of D-amino acids.  

PubMed

Recent work has shed light on the abundance and diversity of D-amino acids in bacterial extracellular/periplasmic molecules, bacterial cell culture, and bacteria-rich environments. Within the extracellular/periplasmic space, D-amino acids are necessary components of peptidoglycan, and disruption of their synthesis leads to cell death. As such, enzymes responsible for D-amino acid synthesis are promising targets for antibacterial compounds. Further, bacteria are shown to incorporate a diverse collection of D-amino acids into their peptidoglycan, and differences in D-amino acid incorporation may occur in response to differences in growth conditions. Certain D-amino acids can accumulate to millimolar levels in cell culture, and their synthesis is proposed to foretell movement from exponential growth phase into stationary phase. While enzymes responsible for synthesis of D-amino acids necessary for peptidoglycan (D-alanine and D-glutamate) have been characterized from a number of different bacteria, the D-amino acid synthesis enzymes characterized to date cannot account for the diversity of D-amino acids identified in bacteria or bacteria-rich environments. Free D-amino acids are synthesized by racemization or epimerization at the ?-carbon of the corresponding L-amino acid by amino acid racemase or amino acid epimerase enzymes. Additionally, D-amino acids can be synthesized by stereospecific amination of ?-ketoacids. Below, we review the roles of D-amino acids in bacterial physiology and biotechnology, and we describe the known mechanisms by which they are synthesized by bacteria. PMID:24752840

Radkov, Atanas D; Moe, Luke A

2014-06-01

88

Amino acid catabolic pathways of lactic acid bacteria.  

PubMed

Lactic acid bacteria (LAB) constitute a diverse group of Gram positive obligately fermentative microorganisms which include both beneficial and pathogenic strains. LAB generally have complex nutritional requirements and therefore they are usually associated with nutrient-rich environments such as animal bodies, plants and foodstuffs. Amino acids represent an important resource for LAB and their utilization serves a number of physiological roles such as intracellular pH control, generation of metabolic energy or redox power, and resistance to stress. As a consequence, the regulation of amino acid catabolism involves a wide set of both general and specific regulators and shows significant differences among LAB. Moreover, due to their fermentative metabolism, LAB amino acid catabolic pathways in some cases differ significantly from those described in best studied prokaryotic model organisms such as Escherichia coli or Bacillus subtilis. Thus, LAB amino acid catabolism constitutes an interesting case for the study of metabolic pathways. Furthermore, LAB are involved in the production of a great variety of fermented products so that the products of amino acid catabolism are also relevant for the safety and the quality of fermented products. PMID:16893752

Fern嫕dez, Mar燰; Z鎴ga, Manuel

2006-01-01

89

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

90

NRPSs and amide ligases producing homopoly(amino acid)s and homooligo(amino acid)s.  

PubMed

Microorganisms are capable of producing a wide variety of biopolymers. Homopoly(amino acid)s and homooligo(amino acid)s, which are made up of only a single type of amino acid, are relatively rare; in fact, only two homopoly(amino acid)s have been known to occur in nature: poly(?-L-lysine) (?-PL) and poly(?-glutamic acid) (?-PGA). Bacterial enzymes that produce homooligo(amino acid)s, such as L-?-lysine-, L-valine-, L-leucine-, L-isoleucine-, L-methionine-, and L-glutamic acid-oligopeptides and poly(?-l-glutamic acid) (?-PGA) have recently been identified, as well as ?-PL synthetase and ?-PGA synthetase. This article reviews the current knowledge about these unique enzymes producing homopoly(amino acid)s and homooligo(amino acid)s. PMID:23817633

Hamano, Yoshimitsu; Arai, Toshinobu; Ashiuchi, Makoto; Kino, Kuniki

2013-08-01

91

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.

Rudnicki, Witold R.; Mroczek, Teresa; Cudek, Pawel

2014-01-01

92

Amino Acids 270 to 510 of the Severe Acute Respiratory Syndrome Coronavirus Spike Protein Are Required for Interaction with Receptor  

Microsoft Academic Search

A novel coronavirus, severe acute respiratory syndrome coronavirus (SARS-CoV), has recently been iden- tified as the causative agent of severe acute respiratory syndrome (SARS). SARS-CoV appears similar to other coronaviruses in both virion structure and genome organization. It is known for other coronaviruses that the spike (S) glycoprotein is required for both viral attachment to permissive cells and for fusion

Gregory J. Babcock; Diana J. Esshaki; William D. Thomas; Donna M. Ambrosino

2004-01-01

93

Amino acid composition in parenteral nutrition: what is the evidence?  

PubMed Central

Purpose of review Complete parenteral nutrition solutions contain mixed amino acid products providing all nine essential amino acids and a varying composition of nonessential amino acids. Relatively little rigorous comparative efficacy research on altered parenteral nutrition amino acid composition has been published in recent years. Recent findings Limited data from randomized, double-blind, adequately powered clinical trials to define optimal doses of total or individual amino acids in parenteral nutrition are available. An exception is the growing number of studies on the efficacy of glutamine supplementation of parenteral nutrition or given as a single parenteral agent. Parenteral glutamine appears to confer benefit in selected patients; however, additional data to define optimal glutamine dosing and the patient subgroups who may most benefit from this amino acid are needed. Although some promising studies have been published, little data are available in the current era of nutrition support on the clinical efficacy of altered doses of arginine, branched chain amino acids, cysteine, or taurine supplementation of parenteral nutrition. Summary Despite routine use of parenteral nutrition, surprisingly little clinical efficacy data are available to guide total or specific amino acid dosing in adult and pediatric patients requiring this therapy. This warrants increased attention by the research community and funding agencies to better define optimal amino acid administration strategies in patient subgroups requiring parenteral nutrition.

Yarandi, Shadi S.; Zhao, Vivian M.; Hebbar, Gautam; Ziegler, Thomas R.

2011-01-01

94

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

95

Digestible amino acids for non-ruminant animals: theory and recent challenges  

Microsoft Academic Search

Accurate assessment of amino acid requirements of livestock for maintenance and growth and accurate supply of these amino acids in feed is essential to optimise growth and production. During passage through the gut and during absorption, the composition of dietary supplied amino acids is modified compared with that absorbed into the portal circulation. Amino acids are utilised for endogenous secretion

P. E. V. Williams

1995-01-01

96

Evaluating lysine requirements of nursery pigs fed low protein diets with different sources of nonessential amino acids.  

PubMed

The Lys requirement of nursery pigs may be dependent on the source of nonessential AA (NEAA) nitrogen or the source of Lys itself. However, little peer-reviewed data examines these phenomena. The objectives of these experiments were to determine if the Lys requirement of pigs is altered when 1) low protein diets are supplemented with different sources of NEAA nitrogen or 2) Lys is supplied as a crystalline source instead of intact protein such as soybean meal (SBM). Two 14-d experiments were conducted using 450 (Exp. 1) and 540 (Exp. 2) pigs (PIC C22/C29 337). There were 10 treatments in each experiment, each aligned as a 2 5 factorial. In Exp. 1, there were 2 sources of NEAA (l-Gln + l-Gly or l-Gly + l-Ala + l-Pro + l-His) and 5 levels of Lys (1.2, 1.3, 1.4, 1.5, and 1.6%). In Exp. 2, there were 2 sources of proteins providing additional Lys (l-Lys HCl or SBM) and the same 5 levels of Lys. Following weaning at 18 to 22 d of age, pigs were fed a common starter diet for 5 d postweaning followed by a 14-d treatment period. Pigs were weighed and feed disappearance determined on d 0, 7, and 14 of the experiment. Data were analyzed using the MIXED and NLIN procedures of SAS (SAS Inst., Cary, NC). In Exp. 1, increasing CP and Lys resulted in a quadratic increase (P < 0.05) in ADG and a linear improvement (P < 0.05) in G:F during the 14-d treatment period. Breakpoint regression analyses revealed that optimum ADG was obtained at 1.36% Lys, while optimum G:F was obtained at 1.45% Lys. The source of NEAA did not affect (P > 0.10) growth performance during the treatment period. In Exp. 2, both ADG and G:F increased linearly (P < 0.05) with increasing Lys. Optimal ADG was obtained at 1.47% Lys, but the breakpoint for optimum G:F was above tested levels. Source of Lys did not affect (P > 0.10) ADG, but pigs fed additional Lys from crystalline sources had improved (P < 0.05) G:F than those fed additional Lys from intact protein at 1.50% Lys; however, the analyzed Lys values at this level differ. Overall, these data show that the standardized ileal digestibility Lys requirement of pigs is not altered when low protein diets are supplemented with different sources of NEAA nitrogen. Feed efficiency appears to be maximized when additional Lys is supplied by l-Lys HCl instead of SBM, but more research is needed to confirm this phenomenon. PMID:25074452

Jones, C K; Tokach, M D; Usry, J L; Neill, C R; Patience, J F

2014-08-01

97

Amino and fatty acids in carbonaceous meteorites  

NASA Technical Reports Server (NTRS)

Analyses of two carbonaceous meteorites have provided much of the latest evidence which seems to support Oparin's theory on the origin of life. The meteorites involved are the Murray meteorite, which fell in 1950, and the Murchison meteorite, which fell in 1969. The amino acids in the two meteorites are similar in composition. Eight of the twenty amino acids found belong to amino acids present in proteins. A number of monocarboxylic and dicarboxylic fatty acids were also found in the meteorites.

Kvenvolden, K. A.

1974-01-01

98

Study on Amino Acid Metabolism and Uremia.  

National Technical Information Service (NTIS)

Histidine supplementation to either low protein diet or essential amino acid diet stimulates positivity of nitrogen balance in a group of 7 uremic patients each one studied for a period of 6 weeks. Imidazoleacetic acid, imidazolepyruvic acid and formimino...

C. Giordano

1970-01-01

99

Active-Site Residues of Escherichia coli DNA Gyrase Required in Coupling ATP Hydrolysis to DNA Supercoiling and Amino Acid Substitutions Leading to Novobiocin Resistance  

Microsoft Academic Search

DNA gyrase is a bacterial type II topoisomerase which couples the free energy of ATP hydrolysis to the introduction of negative supercoils into DNA. Amino acids in proximity to bound nonhydrolyzable ATP analog (AMP PNP) or novobiocin in the gyrase B (GyrB) subunit crystal structures were examined for their roles in enzyme function and novobiocin resistance by site-directed mutagenesis. Purified

Christian H. Gross; Jonathan D. Parsons; Trudy H. Grossman; Paul S. Charifson; Steven Bellon; James Jernee; Maureen Dwyer; Stephen P. Chambers; William Markland; Martyn Botfield; Scott A. Raybuck

2003-01-01

100

The mitochondrial sulfur dioxygenase ETHYLMALONIC ENCEPHALOPATHY PROTEIN1 is required for amino acid catabolism during carbohydrate starvation and embryo development in Arabidopsis.  

PubMed

The sulfur dioxygenase ETHYLMALONIC ENCEPHALOPATHY PROTEIN1 (ETHE1) catalyzes the oxidation of persulfides in the mitochondrial matrix and is essential for early embryo development in Arabidopsis (Arabidopsis thaliana). We investigated the biochemical and physiological functions of ETHE1 in plant metabolism using recombinant Arabidopsis ETHE1 and three transfer DNA insertion lines with 50% to 99% decreased sulfur dioxygenase activity. Our results identified a new mitochondrial pathway catalyzing the detoxification of reduced sulfur species derived from cysteine catabolism by oxidation to thiosulfate. Knockdown of the sulfur dioxygenase impaired embryo development and produced phenotypes of starvation-induced chlorosis during short-day growth conditions and extended darkness, indicating that ETHE1 has a key function in situations of high protein turnover, such as seed production and the use of amino acids as alternative respiratory substrates during carbohydrate starvation. The amino acid profile of mutant plants was similar to that caused by defects in the electron-transfer flavoprotein/electron-transfer flavoprotein:ubiquinone oxidoreductase complex and associated dehydrogenases. Thus, in addition to sulfur amino acid catabolism, ETHE1 also affects the oxidation of branched-chain amino acids and lysine. PMID:24692429

Kr絽l, Lena; Junemann, Johannes; Wirtz, Markus; Birke, Hannah; Thornton, Jeremy D; Browning, Luke W; Poschet, Gernot; Hell, Rdiger; Balk, Janneke; Braun, Hans-Peter; Hildebrandt, Tatjana M

2014-05-01

101

Indigenous amino acids in primitive CR meteorites  

NASA Astrophysics Data System (ADS)

CR chondrites are among the most primitive meteorites. In this paper, we report the first measurements of amino acids in Antarctic CR meteorites. Three CRs, Elephant Moraine (EET) 92042, Graves Nunataks (GRA) 95229, and Grosvenor Mountains (GRO) 95577, were analyzed for their amino acid content using high-performance liquid chromatography with UV fluorescence detection (HPLC-FD) and gas chromatography-mass spectrometry (GC-MS). Our data show that EET 92042 and GRA 95229 are the most amino acid-rich chondrites ever analyzed, with total amino acid concentrations ranging from 180 ppm to 249 ppm. The most abundant amino acids present in the EET 92042 and GRA 95229 meteorites are the ?-amino acids glycine, isovaline, ?-aminoisobutyric acid (?-AIB), and alanine, with ?13C values ranging from +31.6 to +50.5. The carbon isotope results together with racemic enantiomeric ratios determined for most amino acids strongly indicate an extraterrestrial origin for these compounds. Compared to Elephant Moraine (EET) 92042 and GRA 95229, the more aqueously altered GRO 95577 is depleted in amino acids. In both CRs and CMs, the absolute amino acid abundances appear to be related to the degree of aqueous alteration in their parent bodies. In addition, the relative abundances of ?-AIB and ?-alanine in the Antarctic CRs also appear to depend on the degree of aqueous alteration.

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

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

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

104

Dietary amino acid L-tryptophan requirement of fingerling Indian catfish, Heteropneustes fossilis (Bloch), estimated by growth and haemato-biochemical parameters.  

PubMed

An 8-week feeding trial was conducted to determine the dietary tryptophan requirement of fingerling Indian catfish, Heteropneustes fossilis (6.10 1.15 cm, 4.44 0.50 g). Six isonitrogenous (40 g 100 g?) and isoenergetic (17.90 kJ g?) amino acid test diets were formulated with gradation of 0.1 g 100 g? containing graded levels of L-tryptophan (0.04-0.54 g 100 g?, dry diet). Fish were stocked in triplicate groups, in 75-L circular trough with flow-through system and fed experimental diets at 4% BW/day twice daily. Maximum live weight gain (258%), best feed conversion ratio (FCR) (1.54) and protein efficiency ratio (PER) (1.62) were obtained in fish fed diet containing 0.34 g 100 g? tryptophan. However, quadratic regression analysis of weight gain, FCR, PER and body protein deposition (BPD) data indicated requirements for dietary tryptophan at 0.37, 0.33, 0.32 and 0.33 g 100 g? of dry diet, respectively. Significantly (P < 0.05) higher body protein, minimum moisture and intermediate fat contents were recorded at 0.34 g 100 g? dietary tryptophan diet. Ash content was not significantly different (P > 0.05) among treatments except for diets 0.04 and 0.14 g 100 g?. Excellent somatic and haematological indices values were obtained at the requirement level. Based on above results, it is recommended that the diet for H. fossilis should contain tryptophan at 0.32 g 100 g?, dry diet, corresponding to 0.80 g 100 g? dietary protein for optimum growth and efficient feed utilization. PMID:22437368

Ahmed, Imtiaz

2012-08-01

105

Amino Acid Free Energy Decomposition  

NASA Astrophysics Data System (ADS)

The Distance Constraint Model (DCM) describes protein thermodynamics at a coarse-grained level based on a Free Energy Decomposition (FED) that assigns energy and entropy contributions to specific molecular interactions. Application of constraint theory accounts for non-additivity in conformational entropy so that the total free energy of a system can be reconstituted from all its molecular parts. In prior work, a minimal DCM utilized a simple FED involving temperature-independent parameters indiscriminately applied to all residues. Here, we describe a residue-specific FED that depends on local conformational states. The FED of an amino acid is constructed by weighting the energy spectrums associated with local energy minimums in configuration space by absolute entropies estimated using a quasi-harmonic approximation. Interesting temperature-dependent behavior is found. Support is from NIH R01 GM073082 and a CRI postdoctoral Duke research fellowship for H. Wang.

Wang, Hui; Fairchild, Michael; Livesay, Dennis; Jacobs, Donald

2009-03-01

106

A five-amino-acid motif in the undefined region of the TLR8 ectodomain is required for species-specific ligand recognition  

PubMed Central

Toll-like receptors play important roles in regulating immunity against microbial infections. Toll-like receptor 8 (TLR8) belongs to a subfamily comprising TLR7, TLR8 and TLR9. Human TLR8 mediates anti-viral immunity by recognizing ssRNA viruses, and triggers potent anti-viral and antitumor immune responses upon ligation by synthetic small molecular weight ligands. Interestingly, distinct from human TLR8, mouse TLR8 was not responsive to ligand stimulation in the absence of polyT-oligodeoxynucleotides (polyT-ODN). The molecular basis for this distinct ligand recognition is still unclear. In the present study, we compared activation of TLR8 from different species including mouse, rat, human, bovine, porcine, horse, sheep, and cat by ligand ligations. Only the TLR8s from the rodent species (i.e., mouse and rat TLR8s) failed to respond to ligand stimulation in the absence of polyT-ODN. Multiple sequence alignment analysis suggested that these two rodent TLR8s lack a five-amino-acid motif that is conserved in the non-rodent species with varied sequence. This small motif is located in an undefined region of the hTLR8 ectodomain, immediately following LRR-14. Deletion mutation analysis suggested that this motif is essential for the species-specific ligand recognition of hTLR8, whereas it is not required for self-dimerization and intracellular localization of this receptor.

Liu, Jin; Xu, Congfeng; Hsu, Li-Chung; Luo, Yunping; Xiang, Rong; Chuang, Tsung-Hsien

2009-01-01

107

Dissociation of Paramyxovirus Interferon Evasion Activities: Universal and Virus-Specific Requirements for Conserved V Protein Amino Acids in MDA5 Interference ?  

PubMed Central

The V protein of the paramyxovirus subfamily Paramyxovirinae is an important virulence factor that can interfere with host innate immunity by inactivating the cytosolic pathogen recognition receptor MDA5. This interference is a result of a protein-protein interaction between the highly conserved carboxyl-terminal domain of the V protein and the helicase domain of MDA5. The V protein C-terminal domain (CTD) is an evolutionarily conserved 49- to 68-amino-acid region that coordinates two zinc atoms per protein chain. Site-directed mutagenesis of conserved residues in the V protein CTD has revealed both universal and virus-specific requirements for zinc coordination in MDA5 engagement and has also identified other conserved residues as critical for MDA5 interaction and interference. Mutation of these residues produces V proteins that are specifically defective for MDA5 interference and not impaired in targeting STAT1 for proteasomal degradation via the VDC ubiquitin ligase complex. Results demonstrate that mutation of conserved charged residues in the V proteins of Nipah virus, measles virus, and mumps virus also abolishes MDA5 interaction. These findings clearly define molecular determinants for MDA5 inhibition by the paramyxovirus V proteins.

Ramachandran, Aparna; Horvath, Curt M.

2010-01-01

108

Pyrolysis of amino acids - Mechanistic considerations  

NASA Technical Reports Server (NTRS)

Pyrolysis of several structurally different amino acids in a column at 500 C showed differences in the mechanisms and final products. The aliphatic protein amino acids decompose mainly by simple decarboxylation and condensation reactions, while the beta amino acids undergo deamination to unsaturated acids. Alpha amino acids with alpha alkyl substituents undergo an unusual intramolecular SN1 reaction with the formation of an intermediate alpha lactone which decomposes to yield a ketone. The alpha alkyl substituents appear to stabilize the developing negative charge formed by partial heterolytic cleavage of the alpha carbon - NH3 bond. The gamma and delta amino acids give 2-pyrrolidinone and 2-piperidone respectively, while the epsilon acids yield mixed products.

Ratcliff, M. A., Jr.; Medley, E. E.; Simmonds, P. G.

1974-01-01

109

Selective racemization of amino acid amides in the presence of amino acids  

Microsoft Academic Search

The significant differences in the racemization rates of amino acids and the corresponding amides make it possible to carry out selective racemization of amides in the presence of optically active amino acids.

I. A. Yamskov; T. V. Tikhonova; V. E. Tikhonov; V. A. Davankov

1986-01-01

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.

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

2012-01-01

111

Amino acids at the N- and C-termini of human glutamate carboxypeptidase II are required for enzymatic activity and proper folding.  

PubMed

Human glutamate carboxypeptidase II (GCPII) is a co-catalytic metallopeptidase and its putative catalytic domain is homologous to the aminopeptidases from Vibrio proteolyticus and Streptomyces griseus. In humans, the enzyme is expressed predominantly in the nervous system and the prostate. The prostate form, termed prostate-specific membrane antigen, is overexpressed in prostate cancer and is used as a diagnostic marker of the disease. Inhibition of the form of GCPII expressed in the central nervous system has been shown to protect against ischemic injury in experimental animal models. Human GCPII consists of 750 amino acids, and six individual domains were predicted to constitute the protein structure. Here, we report the analysis of the contribution of these putative domains to the structure/function of recombinant human GCPII. We cloned 13 mutants of human GCPII that are truncated or extended at one or both the N- and C-termini of the GCPII sequence. The clones were used to generate stably transfected Drosophila Schneider's cells, and the expression and carboxypeptidase activities of the individual protein products were determined. The extreme C-terminal region of human GCPII was found to be critical for the hydrolytic activity of the enzyme. The deletion of as few as 15 amino acids from the C-terminus was shown to completely abolish the enzymatic activity of GCPII. Furthermore, the GCPII carboxypeptidase activity was abrogated upon removal of more than 60 amino acid residues from the N-terminus of the protein. Overall, these results clearly show that amino acid segments at the N- and C-termini of the ectodomain of GCPII are essential for its carboxypeptidase activity and/or proper folding. PMID:15206943

Barinka, Cyril; Mlcochov, Petra; S塶ha, Pavel; Hilgert, Ivan; Majer, Pavel; Slusher, Barbara S; Horejs, V塶lav; Konvalinka, Jan

2004-07-01

112

Aspergillus nidulans CkiA is an essential casein kinase I required for delivery of amino acid transporters to the plasma membrane  

PubMed Central

Summary Type I casein kinases are highly conserved among Eukaryotes. Of the two Aspergillus nidulans casein kinases I, CkiA is related to the ?/? mammalian kinases and to Saccharomyces cerevisi Hrr25p. CkiA is essential. Three recessive ckiA mutations leading to single residue substitutions, and downregulation using a repressible promoter, result in partial loss-of-function, which leads to a pleiotropic defect in amino acid utilization and resistance to toxic amino acid analogues. These phenotypes correlate with miss-routing of the YAT plasma membrane transporters AgtA (glutamate) and PrnB (proline) to the vacuole under conditions that, in the wild type, result in their delivery to the plasma membrane. Miss-routing to the vacuole and subsequent transporter degradation results in a major deficiency in the uptake of the corresponding amino acids that underlies the inability of the mutant strains to catabolize them. Our findings may have important implications for understanding how CkiA, Hrr25p and other fungal orthologues regulate the directionality of transport at the ER-Golgi interface.

Apostolaki, Angeliki; Harispe, Laura; Calcagno-Pizarelli, Ana Maria; Vangelatos, Ioannis; Sophianopoulou, Vicky; Arst, Herbert N; Penalva, Miguel Angel; Amillis, Sotiris; Scazzocchio, Claudio

2012-01-01

113

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

Microsoft Academic Search

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

Rui Alves; Michael A. Savageau

2005-01-01

114

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

115

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

116

Intramolecular arylation of amino acid enolates.  

PubMed

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

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

2013-10-28

117

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 plant璽舊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.

118

Reexamination of Amino Acids in Lunar Soil.  

National Technical Information Service (NTIS)

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

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

1993-01-01

119

Amino acid chemoreceptors of Bacillus subtilis.  

PubMed Central

Specificities of chemoreceptors for the 20 common amino acids, toward which Bacillus subtilis shows chemotaxis, were assessed by competition ("jamming") experiments using a modification of the traditional capillary assay, called the "sensitivity capillary assay." Many amino acids were sensed by at least two chemoreceptors. All the highest affinity chemoreceptors for the amino acids were distinct, except glutamate and aspartate, which may share one chemoreceptor, and tyrosine, for which the data could not be collected due to low solubility. The data suggest the hypothesis that each amino acid-chemoreceptor complex binds to a different signaler (from each amino acid-chemoreceptor complex binds to a different signaler (from which signals travel to the flagella to modify behavior appropriately), and that many of the signalers can also bind other attractant-chemoreceptor complexes as antagonists (no signals to flagella).

Ordal, G W; Villani, D P; Gibson, K J

1977-01-01

120

Unearthing the root of amino acid similarity.  

PubMed

Similarities and differences between amino acids define the rates at which they substitute for one another within protein sequences and the patterns by which these sequences form protein structures. However, there exist many ways to measure similarity, whether one considers the molecular attributes of individual amino acids, the roles that they play within proteins, or some nuanced contribution of each. One popular approach to representing these relationships is to divide the 20 amino acids of the standard genetic code into groups, thereby forming a simplified amino acid alphabet. Here, we develop a method to compare or combine different simplified alphabets, and apply it to 34 simplified alphabets from the scientific literature. We use this method to show that while different suggestions vary and agree in non-intuitive ways, they combine to reveal a consensus view of amino acid similarity that is clearly rooted in physico-chemistry. PMID:23743923

Stephenson, James D; Freeland, Stephen J

2013-10-01

121

Free amino acid profiling in grain amaranth using LC-MS/MS.  

PubMed

Reliable and reproducible techniques for identification and quantification of amino acids usually require derivatization. However, techniques such as LC-MS/MS may perhaps sideline the derivatization with significant accuracy. Understanding the interaction between free amino acids and several physiological processes apparently requires that the pool be studied in the seed itself. Data on free amino acid content of grain amaranth is very inadequate. The present analysis revealed a higher concentration of essential amino acids especially Threonine and Tryptophan than non essential amino acids. The study constitutes first report of use of LC-MS/MS method for analysing the free amino acid composition of amaranth grain. PMID:23442725

Nimbalkar, Mansingraj S; Pai, Sandeep R; Pawar, Nilesh V; Oulkar, Dashrath; Dixit, Ghansham B

2012-10-15

122

Amino acids in the Martian meteorite Nakhla  

NASA Technical Reports Server (NTRS)

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

Glavin, D. P.; Bada, J. L.; Brinton, K. L.; McDonald, G. D.

1999-01-01

123

Amino acids in the Martian meteorite Nakhla  

PubMed Central

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

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

1999-01-01

124

Gemini surfactants from natural amino acids.  

PubMed

In this review, we report the most important contributions in the structure, synthesis, physicochemical (surface adsorption, aggregation and phase behaviour) and biological properties (toxicity, antimicrobial activity and biodegradation) of Gemini natural amino acid-based surfactants, and some potential applications, with an emphasis on the use of these surfactants as non-viral delivery system agents. Gemini surfactants derived from basic (Arg, Lys), neutral (Ser, Ala, Sar), acid (Asp) and sulphur containing amino acids (Cys) as polar head groups, and Geminis with amino acids/peptides in the spacer chain are reviewed. PMID:24238395

P廨ez, Lourdes; Pinazo, Aurora; Pons, Ramon; Infante, Mrosa

2014-03-01

125

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

126

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

127

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

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)

1998-09-15

129

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

PubMed Central

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

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

2003-01-01

130

Mammalian Target of Rapamycin Complex 1 Activation Is Required for the Stimulation of Human Skeletal Muscle Protein Synthesis by Essential Amino Acids123  

PubMed Central

The relationship between mammalian target of rapamycin complex 1 (mTORC1) signaling and muscle protein synthesis during instances of amino acid surplus in humans is based solely on correlational data. Therefore, the goal of this study was to use a mechanistic approach specifically designed to determine whether increased mTORC1 activation is requisite for the stimulation of muscle protein synthesis following L-essential amino acid (EAA) ingestion in humans. Examination of muscle protein synthesis and signaling were performed on vastus lateralis muscle biopsies obtained from 8 young (25 2 y) individuals who were studied prior to and following ingestion of 10 g of EAA during 2 separate trials in a randomized, counterbalanced design. The trials were identical except during 1 trial, participants were administered a single oral dose of a potent mTORC1 inhibitor (rapamycin) prior to EAA ingestion. In response to EAA ingestion, an ~60% increase in muscle protein synthesis was observed during the control trial, concomitant with increased phosphorylation of mTOR (Ser2448), ribosomal S6 kinase 1 (Thr389), and eukaryotic initiation factor 4E binding protein 1 (Thr37/46). In contrast, prior administration of rapamycin completely blocked the increase in muscle protein synthesis and blocked or attenuated activation of mTORC1-signaling proteins. The inhibition of muscle protein synthesis and signaling was not due to differences in either extracellular or intracellular amino acid availability, because these variables were similar between trials. These data support a fundamental role for mTORC1 activation as a key regulator of human muscle protein synthesis in response to increased EAA availability. This information will be useful in the development of evidence-based nutritional therapies targeting mTORC1 to counteract muscle wasting associated with numerous clinical conditions.

Dickinson, Jared M.; Fry, Christopher S.; Drummond, Micah J.; Gundermann, David M.; Walker, Dillon K.; Glynn, Erin L.; Timmerman, Kyle L.; Dhanani, Shaheen; Volpi, Elena; Rasmussen, Blake B.

2011-01-01

131

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

132

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

133

Hereditary folate malabsorption: A positively charged amino acid at position 113 of the proton-coupled folate transporter (PCFT/SLC46A1) is required for folic acid binding  

SciTech Connect

The proton-coupled folate transporter (PCFT/SLC46A1) mediates intestinal folate uptake at acidic pH. Some loss of folic acid (FA) transport mutations in PCFT from hereditary folate malabsorption (HFM) patients cluster in R113, thereby suggesting a functional role for this residue. Herein, unlike non-conservative substitutions, an R113H mutant displayed 80-fold increase in the FA transport Km while retaining parental Vmax, hence indicating a major fall in folate substrate affinity. Furthermore, consistent with the preservation of 9% of parental transport activity, R113H transfectants displayed a substantial decrease in the FA growth requirement relative to mock transfectants. Homology modeling based on the crystal structures of the Escherichia coli transporter homologues EmrD and glycerol-3-phosphate transporter revealed that the R113H rotamer properly protrudes into the cytoplasmic face of the minor cleft normally occupied by R113. These findings constitute the first demonstration that a basic amino acid at position 113 is required for folate substrate binding.

Lasry, Inbal; Berman, Bluma [The Fred Wyszkowski Cancer Research Laboratory, Dept. of Biology, Technion-Israel Institute of Technology, Haifa 32000 (Israel)] [The Fred Wyszkowski Cancer Research Laboratory, Dept. of Biology, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Glaser, Fabian [Bioinformatics Knowledge Unit, The Lorry I. Lokey Interdisciplinary Center for Life Sciences and Engineering, Technion, Haifa 32000 (Israel)] [Bioinformatics Knowledge Unit, The Lorry I. Lokey Interdisciplinary Center for Life Sciences and Engineering, Technion, Haifa 32000 (Israel); Jansen, Gerrit [Department of Rheumatology, VU University Medical Center, Amsterdam (Netherlands)] [Department of Rheumatology, VU University Medical Center, Amsterdam (Netherlands); Assaraf, Yehuda G., E-mail: assaraf@tx.technion.ac.il [The Fred Wyszkowski Cancer Research Laboratory, Dept. of Biology, Technion-Israel Institute of Technology, Haifa 32000 (Israel)

2009-08-28

134

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 禮 721.2584 Dodecanoic acid, 12-amino-. (a) Chemical substance...substance identified as dodecanoic acid, 12-amino- (PMN P-98-0823;...

2013-07-01

135

Genetics Home Reference: Aromatic l-amino acid decarboxylase deficiency  

MedlinePLUS

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

136

Exposure of amino acids and derivatives in the Earth orbit  

Microsoft Academic Search

Amino acids and amino acid derivatives were exposed to space conditions in Earth orbit as part of the ESA BIOPAN-2 mission to test the possible delivery of extraterrestrial biological building blocks to the primitive Earth. During the Biopan-2 mission, four proteinaceous amino acids (glycine, aspartic acid, glutamic acid and tyrosine), some amino acid esters and two peptides were exposed in

Bernard Barbier; Odile Henin; Fran蔞is Boillot; Annie Chabin; Didier Chaput; Andr Brack

2002-01-01

137

Identification of Conserved Amino Acids in the Herpes Simplex Virus Type 1 UL8 Protein Required for DNA Synthesis and UL52 Primase Interaction in the Virus Replisome*  

PubMed Central

We have used oriS-dependent transient replication assays to search for species-specific interactions within the herpes simplex virus replisome. Hybrid replisomes derived from herpes simplex virus type 1 (HSV-1) and equine herpesvirus type 1 (EHV-1) failed to support DNA replication in cells. Moreover, the replisomes showed a preference for their cognate origin of replication. The results demonstrate that the herpesvirus replisome behaves as a molecular machine relying on functionally important interactions. We then searched for functional interactions in the replisome context by subjecting HSV-1 UL8 protein to extensive mutagenesis. 52 mutants were made by replacing single or clustered charged amino acids with alanines. Four mutants showed severe replication defects. Mutant A23 exhibited a lethal phenotype, and mutants A49, A52 and A53 had temperature-sensitive phenotypes. Mutants A49 and A53 did not interact with UL52 primase as determined by co-immunoprecipitation experiments. Using GFP-tagged UL8, we demonstrate that all mutants were unable to support formation of ICP8-containing nuclear replication foci. Extended mutagenesis suggested that a highly conserved motif corresponding to mutant A49 serves an important role for establishing a physical contact between UL8 and UL52. The replication-defective mutations affected conserved amino acids, and similar phenotypes were observed when the corresponding mutations were introduced into EHV-1 UL8.

Muylaert, Isabella; Zhao, Zhiyuan; Andersson, Torbjorn; Elias, Per

2012-01-01

138

Homology-based modeling of the Erwinia amylovora type III secretion chaperone DspF used to identify amino acids required for virulence and interaction with the effector DspE.  

PubMed

The structure of DspF, a type III secretion system (T3SS) chaperone required for virulence of the fruit tree pathogen Erwinia amylovora, was modeled based on predicted structural homology to characterized T3SS chaperones. This model guided the selection of 11 amino acid residues that were individually mutated to alanine via site-directed mutagenesis. Each mutant was assessed for its effect on virulence complementation, dimerization and interaction with the N-terminal chaperone-binding site of DspE. Four amino acid residues were identified that did not complement the virulence defect of a dspF knockout mutant, and three of these residues were required for interaction with the N-terminus of DspE. This study supports the significance of the predicted beta-sheet helix-binding groove in DspF chaperone function. PMID:20600860

Triplett, Lindsay R; Wedemeyer, William J; Sundin, George W

2010-09-01

139

Amino Acid Metabolism in Uremia of Man.  

National Technical Information Service (NTIS)

Comparative studies on the intestinal absorption of tryptophan in normal subjects, end-stage uremics, and patients maintained by hemodialysis demonstrated that absorption of this essential amino acid is defective in the patients. Rates of clearance of the...

J. H. Peters, P. F. Gulyassy, P. Schoenfeld

1972-01-01

140

Amino Acid Biosynthesis Pathways in Diatoms  

PubMed Central

Amino acids are not only building blocks for proteins but serve as precursors for the synthesis of many metabolites with multiple functions in growth and other biological processes of a living organism. The biosynthesis of amino acids is tightly connected with central carbon, nitrogen and sulfur metabolism. Recent publication of genome sequences for two diatoms Thalassiosira pseudonana and Phaeodactylum tricornutum created an opportunity for extensive studies on the structure of these metabolic pathways. Based on sequence homology found in the analyzed diatomal genes, the biosynthesis of amino acids in diatoms seems to be similar to higher plants. However, one of the most striking differences between the pathways in plants and in diatomas is that the latter possess and utilize the urea cycle. It serves as an important anaplerotic pathway for carbon fixation into amino acids and other N-containing compounds, which are essential for diatom growth and contribute to their high productivity.

Bromke, Mariusz A.

2013-01-01

141

How to build optically active ? -amino acids  

Microsoft Academic Search

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

M. Calmes; J. Daunis

1999-01-01

142

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

PubMed Central

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

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

2008-01-01

143

Fullerene amino acid interactions. A theoretical study  

NASA Astrophysics Data System (ADS)

In this work we explore the ability of the C 60 fullerene to interact with amino acids at the DFT-B3LYP/3-21G? level of theory. The calculations suggest that the most favorable interactions of the fullerene is with arginine, leucine, and tryptophan which is related to the backbone structure of the corresponding amino acids. We propose correlations of the dissociation energies, HOMO/LUMO band gaps and hydrophobicity constants in relation to the computed quantum chemical behavior.

Leon, Aned de; Jalbout, Abraham F.; Basiuk, Vladimr A.

2008-02-01

144

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

145

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

146

Amino Acid Degradation after Meteoritic Impact Simulation  

NASA Astrophysics Data System (ADS)

Our study concerns the hypothesis that prebiotic organic matter, present on Earth, was synthesized in the interstellar environment, and then imported to Earth by the 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 (Munoz Caro, et al. Nature 416, 403 (2002).). We are now interested in the effects of space conditions and meteoritic impact on these amino acids (Barbier B., et al. Planet. Space Sci. 46, 391 (1998), Barbier B., et al. , Planet. Space Sci. 50, 353 (2002) ; Boillot F., et al. Origins of Life and Evol. Biosphere 32, 359 (2002)). Most of the extraterrestrial organic molecules known today have been identified in carbonaceous chondrite meteorites. One of the components of these meteorites is a clay with a composition close to that of saponite. Thus, in order to study the effects of meteoritic impact on amino acids, three amino acids (alanine, glycine, and b-alanine) were mixed with 0,275 mg saponite clay to simulate a carbonaceous chondrite meteorite. These three amino acids were identified in the Murchison meteorite, and two of them (Gly and Ala) are used in biological systems. A pressure of 15 GPa, simulating a meteorite impact with a velocity of 1.2 km/sec was applied to this artificial meteorite at the NASA Johnson Space Center Experimental Impact Laboratory. The sample extracts show a good preservation of the amino acids : 34% of glycine, about 46% of D-alanine and about 20% of b-alanine were preserved. Another experiment has been carried out using different amino-acids and higher pressures. We are now analyzing the samples. The preparation and the analysis of samples were carried out in Orl嶧ns (France) at the Molecular Biophysics Center.

Bertrand, M.; van der Gaast, S.; Vilas, F.; Horz, F.; Barnes, G.; Barbier, B.; Chabin, A.; Braak, A.; Westall, A.

2004-11-01

147

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 禮 721.1705 Benzoic acid, 3-amino-, diazotized, coupled with...generically identified as benzoic acid, 3-amino-, diazotized, coupled...

2013-07-01

148

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

149

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

Code of Federal Regulations, 2010 CFR

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

2009-07-01

150

A biosensor for all D-amino acids using evolved D-amino acid oxidase.  

PubMed

Determination of the D-amino acid content in foods and in biological samples is a very important task. In order to achieve this goal we developed a biosensor employing the flavoenzyme D-amino acid oxidase from the yeast Rhodotorula gracilis. To produce a device in which the D-amino acid composition does not alter the results, both the wild-type and a number of mutants obtained by rational design and directed evolution approaches were used. An analysis of D-amino acid oxidase mutants activity on D-amino acid mixtures containing various ratios of neutral, acidic, and basic substrates identified the Amberzyme-immobilized T60A/Q144R/K152E and M213G mutants as the best choice: their response shows an only limited dependence on the solution composition when at least 20% of the D-amino acid is made up of D-alanine (standard error is approximately 5-9%). This is the first report, to our knowledge, demonstrating that the entire D-amino acid content can be determined by using a screen-printed electrode amperometric biosensor, with a detection limit of 0.25 mM and a mean response time of 10-15 min. The D-amino acid assay based on R. gracilis DAAO-biosensor is inexpensive, simple to perform, and rapid: the D-amino acid concentration of a variety of biological samples can be investigated using this assay. PMID:18588925

Rosini, Elena; Molla, Gianluca; Rossetti, Carlo; Pilone, Mirella S; Pollegioni, Loredano; Sacchi, Silvia

2008-07-31

151

Protein and sulphur amino acid nutrition of hair fibre-producing Angora and Cashmere goats  

Microsoft Academic Search

The results from a number of studies are presented which investigated responses in fibre production of British Cashmere and Angora goats to variation in protein and sulphur amino acid nutrition under conditions of active fibre growth. Requirements for amino acids were considered in the context of the concentration of amino acids, including cysteine and methionine, in rumen microbial protein and

H. Galbraith

2000-01-01

152

Plasma amino acid levels and amino acid losses during continuous ambulatory peritoneal  

Microsoft Academic Search

Free amino acid losses into dialysate during a 24-h collection period and postahsorptiveplasma amino acid concentrations were measured in 14 studiesin nine clinically stable men undergoing continuous ambulatory peritoneal dialysis. Patients ingested diets containing 97 18 (SD) g\\/day of protein in a metabolic research unit. Total amino acid losses were 3.4 1.2 g\\/24 h and represented 3.9

Joel D Kopple; Michael J Blumenkrantz; Michael R Jones; John K Moran

153

Evidence of Selection for Low Cognate Amino Acid Bias in Amino Acid Biosynthetic Enzymes  

PubMed Central

Summary If the enzymes responsible for biosynthesis of a given amino acid are repressed and the cognate amino acid pool suddenly depleted, then derepression of these enzymes and replenishment of the pool would be problematic, if the enzymes were largely composed of the cognate amino acid. In the proverbial Catch 22, cells would lack the necessary enzymes to make the amino acid, and they would lack the necessary amino acid to make the needed enzymes. Based on this scenario, we hypothesize that evolution would lead to the selection of amino acid biosynthetic enzymes that have a relatively low content of their cognate amino acid. We call this the cognate bias hypothesis. Here we test several implications of this hypothesis directly using data from the proteome of Escherichia coli. Several lines of evidence show that low cognate bias is evident in 15 of the 20 amino acid biosynthetic pathways. Comparison with closely related Salmonella typhimurium shows similar results. Comparison with more distantly related Bacillus subtilis shows general similarities as well as significant differences in the detailed profiles of cognate bias. Thus, selection for low cognate bias plays a significant role in shaping the amino acid composition for a large class of cellular proteins.

Alves, Rui; Savageau, Michael A.

2006-01-01

154

D-Amino acid oxidase: new findings.  

PubMed

The most recent research on D-amino acid oxidases and D-amino acid metabolism has revealed new, intriguing properties of the flavoenzyme and enlighted novel biotechnological uses of this catalyst. Concerning the in vivo function of the enzyme, new findings on the physiological role of D-amino acid oxidase point to a detoxifying function of the enzyme in metabolizing exogenous D-amino acids in animals. A novel role in modulating the level of D-serine in brain has also been proposed for the enzyme. At the molecular level, site-directed mutagenesis studies on the pig kidney D-amino acid oxidase and, more recently, on the enzyme from the yeast Rhodotorula gracilis indicated that the few conserved residues of the active site do not play a role in acid-base catalysis but rather are involved in substrate interactions. The three-dimensional structure of the enzyme was recently determined from two different sources: at 2.5-3.0 A resolution for DAAO from pig kidney and at 1.2-1.8 A resolution for R. gracilis. The active site can be clearly depicted: the striking absence of essential residues acting in acid-base catalysis and the mode of substrate orientation into the active site, taken together with the results of free-energy correlation studies, clearly support a hydrid transfer type of mechanism in which the orbital steering between the substrate and the isoalloxazine atoms plays a crucial role during catalysis. PMID:11130179

Pilone, M S

2000-11-01

155

Amino acids derived from Titan tholins  

NASA Technical Reports Server (NTRS)

An organic heteropolymer (Titan tholin) was produced by continuous dc discharge through a 0.9 N2/0.1 CH4 gas mixture at 0.2 mbar pressure, roughly simulating the cloudtop atmosphere of Titan. Treatment of this tholin with 6N HCl yielded 16 amino acids by gas chromatography after derivatization of N-trifluroacetyl isopropyl esters on two different capillary columns. Identifications were confirmed by GC/MS. Glycine, aspartic acid, and alpha- and beta-alanine were produced in greatest abundance; the total yield of amino acids was approximately 10(-2), approximately equal to the yield of urea. The presence of "nonbiological" amino acids, the absence of serine, and the fact that the amino acids are racemic within experimental error together indicate that these molecules are not due to microbial or other contamination, but are derived from the tholin. In addition to the HCN, HC2CN, and (CN)2 found by Voyager, nitriles and aminonitriles should be sought in the Titanian atmosphere and, eventually, amino acids on the surface. These results suggest that episodes of liquid water in the past or future of Titan might lead to major further steps in prebiological organic chemistry on that body.

Khare, B. N.; Sagan, C.; Ogino, H.; Nagy, B.; Er, C.; Schram, K. H.; Arakawa, E. T.

1986-01-01

156

Detection of non-protein amino acids in the presence of protein amino acids. II.  

NASA Technical Reports Server (NTRS)

Studies conducted with the JEOL 5AH amino acid analyzer are described. This instrument makes possible the programming of the chromatographic process. Data are presented showing the separations of seventeen non-protein amino acids in the presence of eighteen protein amino acids. It is pointed out that distinct separations could be obtained in the case of a number of chemically similar compounds, such as ornithine and lysine, N-amidino alanine and arginine, and iminodiacetic acid and S-carboxymethyl cysteine and aspartic acid.

Shapshak, P.; Okaji, M.

1972-01-01

157

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

158

Amino Acids Profiles in Biological Media  

NASA Astrophysics Data System (ADS)

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 m0.25 mm, 0.25 ?m film thickness, using a temperature program from 50 蚓, 1 min, 6 蚓/min at 100 蚓, 4 蚓/min at 200 蚓, 20 蚓/min at 300 蚓, (3 min). The transfer line temperature was 250 蚓, the injector temperature 200 蚓 and ion source temperature 250 蚓 splitter: 10:1. Electron energy was 70 eV and emission current, 100 ?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.; Horj, E.; Ani, A. R.; Mesaros, C.; Morar, S.; Cozar, O.; Culea, M.

2010-08-01

159

Immunonutrition: role of sulfur amino acids, related amino acids, and polyamines  

Microsoft Academic Search

Pro-inflammatory cytokines mediate widespread changes in protein metabolism. Amino acids released from peripheral tissues fulfill a number of functions. They act as substrate for acute phase protein and immunoglobulin synthesis and, together with polyamines, in the replication of immune cells. Demands for specific amino acids may outstrip the supply from endogenous sources. A number of strands of evidence suggest that

Robert F. Grimble; George K. Grimble

1998-01-01

160

Economic aspects of amino acids production.  

PubMed

Amino acids represent basic elements of proteins, which as a main source of nutrition themselves serve as a major reserve for maintaining essential functions of humans as well as animals. Taking the recent state of scientific knowledge into account, the industrial sector of amino acids is a priori "suitable" to a specific kind of an ecologically sound way of production, which is based on biotechnology. The following article may point out characteristics of this particular industrial sector and illustrates the applicability of the latest economic methods, founded on development of the discipline of bionics in order to describe economic aspects of amino acids markets. The several biochemical and technological fields of application of amino acids lead to specific market structures in high developed and permanently evolving systems. The Harvard tradition of industrial economics explains how market structures mould the behaviour of the participants and influences market results beyond that. A global increase in intensity of competition confirms the notion that the supply-side is characterised by asymmetric information in contrast to Kantzenbachs concept of "narrow oligopoly" with symmetrical shared knowledge about market information. Departing from this point, certain strategies of companies in this market form shall be derived. The importance of Research and Development increases rapidly and leads to innovative manufacturing methods which replace more polluting manufacturing processes like acid hydrolysis. In addition to these modifications within the production processes the article deals furthermore with the pricing based on product life cycle concept and introduces specific applications of tools like activity based costing and target costing to the field of amino acid production. The authors come to the conclusion that based on a good transferability of latest findings in bionics and ecological compatibility competitors in amino acids manufacturing are well advised to exercise concepts of the management of complex systems in order to choose the right strategy towards gaining market leadership. PMID:12523391

Mueller, Udo; Huebner, Susanna

2003-01-01

161

Early parenteral feeding of amino acids.  

PubMed Central

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

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

1989-01-01

162

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

163

Glutamate: a truly functional amino acid.  

PubMed

Glutamate is one of the most abundant of the amino acids. In addition to its role in protein structure, it plays critical roles in nutrition, metabolism and signaling. Post-translational carboxylation of glutamyl residues increases their affinity for calcium and plays a major role in hemostasis. Glutamate is of fundamental importance to amino acid metabolism, yet the great bulk of dietary glutamate is catabolyzed within the intestine. It is necessary for the synthesis of key molecules, such as glutathione and the polyglutamated folate cofactors. It plays a major role in signaling. Within the central nervous system, glutamate is the major excitatory neurotransmitter and its product, GABA, the major inhibitory neurotransmitter. Glutamate interaction with specific taste cells in the tongue is a major component of umami taste. The finding of glutamate receptors throughout the gastrointestinal tract has opened up a new vista in glutamate function. Glutamate is truly a functional amino acid. PMID:22526238

Brosnan, John T; Brosnan, Margaret E

2013-09-01

164

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

165

Subtilisin-like proprotein convertase paired basic amino acid-cleaving enzyme4 is required for chondrogenic differentiation in ATDC5 cells.  

PubMed

Bone morphogenetic proteins (BMPs) have been implicated in the regulation of multiple stages of endochondral bone development. BMPs are synthesized as inactive precursors, and activated by removal of the propeptide. The subtilisin-like proprotein convertase (SPC) family comprises seven members [furin/SPC1, PC2/SPC2, PC1/PC3/SPC3, paired basic amino acid-cleaving enzyme4 (PACE4)/SPC4, PC4/SPC5, PC6/PC5/SPC6, and PC8/PC7/LPC/SPC7], and activates various signaling molecules, including BMPs. In this study, we analyzed the role of this family in chondrogenic differentiation by using the mouse embryonal carcinoma-derived clonal cell line ATDC5. Both SPC-specific inhibitors, decanoyl-Arg-Val-Lys-Arg-chloromethylketone and ?1-antitrypsin Portland variant, suppressed chondrogenic differentiation. RT-PCR analysis revealed that PACE4 mRNA levels increased markedly during chondrogenic differentiation, whereas furin expression remained unchanged. Knockdown of PACE4 expression significantly reduced chondrogenic differentiation. Furthermore, proBMP6, which shows an expression pattern similar to that of PACE4, was efficiently processed into its mature form by PACE4, whereas furin could not process proBMP6. These results suggest that PACE4 may regulate the rate of hypertrophic conversion of ATDC5 cells through activation of proBMP6. PMID:22925071

Yuasa, Keizo; Futamatsu, Go; Kawano, Tsuyoshi; Muroshita, Masaki; Kageyama, Yoko; Taichi, Hiromi; Ishikawa, Hiroshi; Nagahama, Masami; Matsuda, Yoshiko; Tsuji, Akihiko

2012-11-01

166

Amino Acid Transport by the Filamentous Fungus Arthrobotrys conoides1  

PubMed Central

Uptake of l-valine by germinated spores of Arthrobotrys conoides has all the characteristics of a system of transport that requires an expenditure of energy by the cells. It is dependent on temperature and has an energy of activation of 16,000 cal/mole. Uptake is optimal at pH 5 to 6. l-Valine accumulated against a concentration gradient and is not lost from the cells by leakage or exchange. The process requires energy supplied by the metabolic reactions that are inhibited by catalytic amounts of 2,4-dinitrophenol and azide. The kinetics of the system are consistent with a mechanism of transport that depends on a limited number of sites on the cell surface, and the Michaelis constant for the system is 1.5 10?5 to 7.5 10?5m. Modification of the amino or carboxyl group abolishes l-valine uptake. The process is competitively inhibited by d-valine, glycine, and other neutral amino acids (Ki = 1.5 10?5 to 4.0 10?5m), indicating a lack of stereospecificity, and also indicating that aliphatic side chain is not required for binding with the carrier. The transport system has less affinity for acidic amino acids (glutamic and aspartic acids) than neutral amino acids, and a greater affinity for basic amino acids (histidine, lysine, and arginine). The range of affinity is in the order of 100, as measured in terms of Ki values for various compounds. The data presented provide suggestive evidence that the uptake by A. conoides of all amino acids except proline is mediated by a single carrier system that possesses an overall negative charge.

Gupta, Rishab K.; Pramer, David

1970-01-01

167

CSF gradients for amino acid neurotransmitters.  

PubMed Central

Amino acid concentrations were measured in CSF samples obtained by lumbar puncture in 51 patients, cervical puncture in 16 patients, spinal drains in nine patients, ventricular taps in five patients and from below a spinal block in six patients. There was evidence of a rostrocaudal gradient for GABA and taurine and a reverse gradient for alanine and asparagine. Lumbar CSF glycine concentrations rose with increasing age whilst GABA concentrations fell. Women had significantly lower concentrations of asparagine and glutamine and elevated taurine compared to men. The influence of biological factors and gradients must be taken into account before the interpretation of changes in CSF amino acid concentrations.

Crawford, P M; Lloyd, K G; Chadwick, D W

1988-01-01

168

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 Palac藕要 (University of Barcelona Department of Biochemistry and Molecular Biology); Virginia Nunes (Institut de Recerca Oncol藕涿ica Centre de Gen藕系ica M藕牡ica i Molecular); Mariona Font-Llitj藕連 (Institut de Recerca Oncol藕涿ica Centre de Gen藕系ica M藕牡ica i Molecular); Maite Jim藕姊ez-Vidal (University of Barcelona,Institut de Recerca Oncol藕涿ica Department of Biochemistry and Molecular Biology,Centre de Gen藕系ica M藕牡ica i Molecular); Joana Fort (University of Barcelona Department of Biochemistry and Molecular Biology); Emma Gasol (University of Barcelona Department of Biochemistry and Molecular Biology)

2005-04-01

169

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

PubMed Central

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

Yamaguchi, Shigenori; Komeda, Hidenobu; Asano, Yasuhisa

2007-01-01

170

Amino acid transceptors: gate keepers of nutrient exchange and regulators of nutrient signaling  

PubMed Central

Amino acid transporters at the surface of cells are in an ideal location to relay nutritional information, as well as nutrients themselves, to the cell interior. These transporters are able to modulate signaling downstream of intracellular amino acid receptors by regulating intracellular amino acid concentrations through processes of coupled transport. The concept of dual-function amino acid transporter/receptor (or transceptor) proteins is well established in primitive eukaryotes such as yeast, where detection of extracellular amino acid deficiency leads to upregulation of proteins involved in biosynthesis and transport of the deficient amino acid(s). The evolution of the extracellular milieu and nutrient-regulated endocrine controls in higher eukaryotes, alongside their frequent inability to synthesize all proteinaceous amino acids (and, hence, the requirement for indispensable amino acids in their diet), appears to have lessened the priority of extracellular amino acid sensing as a stimulus for metabolic signals. Nevertheless, recent studies of amino acid transporters in flies and mammalian cell lines have revealed perhaps unanticipated echoes of these transceptor functions, which are revealed by cellular stresses (notably starvation) or gene modification/silencing. APC-transporter superfamily members, including slimfast, path, and SNAT2 all appear capable of sensing and signaling amino acid availability to the target of rapamycin (TOR) pathway, possibly through PI 3-kinase-dependent mechanisms. We hypothesize (by extrapolation from knowledge of the yeast Ssy1 transceptor) that, at least for SNAT2, the transceptor discriminates between extracellular and intracellular amino acid stimuli when evoking a signal.

Hundal, Harinder S.; Taylor, Peter M.

2009-01-01

171

Sensitive Amino Acid Composition and Chirality Analysis with the Mars Organic Analyzer (MOA)  

NASA Technical Reports Server (NTRS)

Detection of life on Mars requires definition of a suitable biomarker and development of sensitive yet compact instrumentation capable of performing in situ analyses. Our studies are focused on amino acid analysis because amino acids are more resistant to decomposition than other biomolecules, and because amino acid chirality is a well-defined biomarker. Amino acid composition and chirality analysis has been previously demonstrated in the lab using microfabricated capillary electrophoresis (CE) chips. To analyze amino acids in the field, we have developed the Mars Organic Analyzer (MOA), a portable analysis system that consists of a compact instrument and a novel multi-layer CE microchip.

Skelley, Alison M.; Scherer, James R.; Aubrey, Andrew D.; Grover, William H.; Ivester, Robin H. C.; Ehrenfreund, Pascale; Grunthaner, Frank J.; Bada, Jeffrey L.; Mathies, Richard A.

2005-01-01

172

Differential diagnosis of (inherited) amino acid metabolism or transport disorders  

Microsoft Academic Search

Disorders of amino acid metabolism or transport are most clearly expressed in urine. Nevertheless the interpretation of abnormalities in urinary amino acid excretion remains difficult. An increase or decrease of almost every amino acid in urine can be due to various etiology. To differentiate between primary and secondary aminoacido-pathies systematic laboratory investigation is necessary. Early diagnosis of disorders of amino

W. Blom; J. G. M. Huijmans

1992-01-01

173

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

SciTech Connect

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

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

1987-11-01

174

The Ubiquitin-Specific Protease Family from Arabidopsis. AtUBP1 and 2 Are Required for the Resistance to the Amino Acid Analog Canavanine1  

PubMed Central

Ubiquitin-specific proteases (UBPs) are a family of unique hydrolases that specifically remove polypeptides covalently linked via peptide or isopeptide bonds to the C-terminal glycine of ubiquitin. UBPs help regulate the ubiquitin/26S proteolytic pathway by generating free ubiquitin monomers from their initial translational products, recycling ubiquitins during the breakdown of ubiquitin-protein conjugates, and/or by removing ubiquitin from specific targets and thus presumably preventing target degradation. Here, we describe a family of 27 UBP genes from Arabidopsis that contain both the conserved cysteine (Cys) and histidine boxes essential for catalysis. They can be clustered into 14 subfamilies based on sequence similarity, genomic organization, and alignments with their closest relatives from other organisms, with seven subfamilies having two or more members. Recombinant AtUBP2 functions as a bona fide UBP: It can release polypeptides attached to ubiquitins via either ?- or ?-amino linkages by an activity that requires the predicted active-site Cys within the Cys box. From the analysis of T-DNA insertion mutants, we demonstrate that the AtUBP1 and 2 subfamily helps confer resistance to the arginine analog canavanine. This phenotype suggests that the AtUBP1 and 2 enzymes are needed for abnormal protein turnover in Arabidopsis.

Yan, Ning; Doelling, Jed H.; Falbel, Tanya G.; Durski, Adam M.; Vierstra, Richard D.

2000-01-01

175

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

176

Polymerization of amino acids containing nucleotide bases  

NASA Technical Reports Server (NTRS)

The nucleoamino acids 1-(3'-amino,3'-carboxypropyl)uracil (3) and 9-(3'-amino,3'-carboxypropyl)adenine (4) have been prepared as (L)-en-antiomers and as racemic mixtures. When 3 or 4 is suspended in water and treated with N,N'-carbon-yldiimidazole, peptides are formed in good yield. The products formed from the (L)-enantiomers are hydrolyzed to the monomeric amino acids by pronase. Attempts to improve the efficiency of these oligomerizations by including a polyuridylate template in the reaction mixture were not successful. Similarly, oligomers derived from the (L)-enantiomer of 3 did not act as templates to facilitate the oligomerization of 4.

Ben Cheikh, Azzouz; Orgel, Leslie E.

1990-01-01

177

Structual comparison of dermatopontin amino acid sequences  

Microsoft Academic Search

Dermatopontin is a tyrosine-rich acidic extracellular matrix protein of 22 kD with possible functions in cellmatrix interactions\\u000a and matrix assembly. Database of GenBank+EMBL+DDBJ sequences from Nucleotide, Gene, and Expressed Sequence Tag (EST) Divisions\\u000a was searched with a keyword dermatopontin or mouse dermatopontin amino acid sequence. In addition to five mammals previously\\u000a described, five mammalian, two bird, one fish dermatopontin genes

Takumi Takeuchi

2010-01-01

178

Carbon edge XANES spectroscopy of amino acids and peptides  

Microsoft Academic Search

Carbon edge X-ray absorption near-edge structures (XANES) of amino acids and small peptides have been investigated for the first time. Because of the heat sensitivity of the samples, gas phase spectroscopy of evaporated samples is difficult. Therefore they were analyzed in solid form as thin films. Quantitative absorption measurements require the region of the sample which is illuminated to be

J Boese; A Osanna; C Jacobsen; J Kirz

1997-01-01

179

Identification of Amino Acid Residues of ERH Required for Its Recruitment to Nuclear Speckles and Replication Foci in HeLa Cells  

PubMed Central

ERH is a small, highly evolutionarily conserved nuclear protein of unknown function. Its three-dimensional structure is absolutely unique and it can form a homodimer through a ? sheet surface. ERH has been shown to interact, among others, with PDIP46/SKAR and Ciz1. When coexpressed with the latter protein, ERH accumulates in replication foci in the nucleus of HeLa cells. Here, we report that when ERH is coexpressed with PDIP46/SKAR in HeLa cells, it is recruited to nuclear speckles, and identify amino acid residues critical for targeting ERH to both these subnuclear structures. ERH H3A Q9A shows a diminished recruitment to nuclear speckles but it is recruited to replication foci. ERH E37A T51A is very poorly recruited to replication foci while still accumulating in nuclear speckles. Consequently, ERH H3A Q9A E37A T51A is recruited neither to nuclear speckles nor to replication foci. The lack of interactions of these three ERH forms with PDIP46/SKAR and/or Ciz1 was further confirmed in vitro by GST pull-down assay. The residues whose substitutions interfere with the accumulation in nuclear speckles are situated on the ? sheet surface of ERH, indicating that only the monomer of ERH can interact with PDIP46/SKAR. Substitutions affecting the recruitment to replication foci map to the other side of ERH, near a long loop between the ?1 and ?2 helices, thus both the monomer and the dimer of ERH could interact with Ciz1. The construction of the ERH mutants not recruited to nuclear speckles or replication foci will facilitate further studies on ERH actions in these subnuclear structures.

Banko, Monika I.; Krzyzanowski, Marek K.; Turcza, Paulina; Maniecka, Zuzanna; Kulis, Marta; Kozlowski, Piotr

2013-01-01

180

Protein tolerance to random amino acid change  

Microsoft Academic Search

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

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

2004-01-01

181

Phenylketonuria: Defects in Amino Acid Metabolism  

Microsoft Academic Search

Phenylketonuria (PKU) is the most common disorder of amino acid metabolism affecting the PAH gene, which encodes for the enzyme phenylalanine hydroxylase. This defect results in toxic hyperphenylalanemia from a breakdown in the hydroxylation of phenylalanine (Phe) to tyrosine, the first step in the catabolic metabolism of Phe. This defect causes the symptoms of PKU, which include profound mental retardation

Matthew Madden

182

Aromatic amino acid hydroxylase genes and schizophrenia  

Microsoft Academic Search

Phenylalanine hydroxylase (PAH), which catalyzes the conversion of phenylalanine to tyrosine, shares physical, structural and catalytic properties with tyrosine hydroxy- lase (TH) and tryptophan hydroxylase (TPH) that catalyze the rate-limiting steps in the biosynthesis of the neurotransmitters dopa- mine, noradrenaline, and serotonin. Be- cause these neurotransmitter systems have all been implicated in the pathophysiology of schizophrenia, the aromatic amino acid

Helen M. Chao; Mary Ann Richardson

2002-01-01

183

High-pressure polymorphism in amino acids  

Microsoft Academic Search

Pressure up to 10 GPa is a powerful method for studying polymorphism in organic crystal structures, and this review surveys work carried out on high-pressure polymorphism in amino acids. High-pressure polymorphs have been established crystallographically for glycine, alanine, serine, cysteine and leucine. Phase transitions can be driven by the avoidance of very short intermolecular contacts or by promotion of a

Stephen A. Moggach; Simon Parsons; Peter A. Wood

2008-01-01

184

Enantioenrichment in sublimed amino acid mixtures.  

PubMed

A real amplification of an initial enantiomeric excess can be detected when two amino acids are sublimed at high temperature, even if one of the components is a racemic compound that does not convert into a conglomerate by sublimation. PMID:22388769

Viedma, Crist鏏al; Ortiz, Jos E; de Torres, Trinidad; Cintas, Pedro

2012-04-14

185

Amino Acid Sequence of Human Cholinesterase.  

National Technical Information Service (NTIS)

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

O. Lockridge

1985-01-01

186

Amino Acid Formation on Interstellar Dust Particles  

NASA Astrophysics Data System (ADS)

In the dense interstellar medium dust particles accrete ice layers of known molecular composition. In the diffuse interstellar medium these ice layers are subjected to energetic UV-irradiation. Here, photoreactions form complex organic molecules. The interstellar processes were recently successfully simulated in two laboratories. At NASA Ames Research Center three amino acids were detected in interstellar ice analogues [1], contemporaneously, our European team reported on the identification of 16 amino acids therein [2]. Amino acids are the molecular building blocks of proteins in living organisms. The identification of amino acids on the simulated icy surface of interstellar dust particles strongly supports the assumption that the precursor molecules of life were delivered from interstellar and interplanetary space via (micro-) meteorites and/or comets to the earyl Earth. The results shall be verified by the COSAC experiment onboard the ESA cometary mission Rosetta [3]. [1] M.P. Bernstein, J.P. Dworkin, S.A. Sandford, G.W. Cooper, L.J. Allamandola: itshape Nature \\upshape 416 (2002), 401-403. [2] G.M. Mu隳z Caro, U.J. Meierhenrich, W.A. Schutte, B. Barbier, A. Arcones Sergovia, H. Rosenbauer, W.H.-P. Thiemann, A. Brack, J.M. Greenberg: itshape Nature \\upshape 416 (2002), 403-406. [3] U. Meierhenrich, W.H.-P. Thiemann, H. Rosenbauer: itshape Chirality \\upshape 11 (1999), 575-582.

Meierhenrich, U. J.; Munoz Caro, G. M.; Barbier, B.; Brack, A.; Thiemann, W.; Goesmann, F.; Rosenbauer, H.

2003-04-01

187

Analytical techniques for the detection of ?-amino-?-methylaminopropionic acid.  

PubMed

The non-protein amino acid L-?-amino-?-methylaminopropionic acid (BMAA) has been linked to several neurodegenerative diseases. Its presence in trace amounts in complex sample such as bacterial, plant and mammalian tissue extracts and hydrolyzates makes analysis a complicated process requiring good analytical technique. There are conflicting reports in the literature regarding the presence or absence of BMAA in key samples, but the absence of standardized or validated methods makes comparison of the disparate findings difficult to compare. This critical review will summarize the historic and recent literature, and provide suggestions for improving the methods currently in practice. PMID:22421821

Cohen, Steven A

2012-05-01

188

Amino Acid Metabolism of Pea Leaves  

PubMed Central

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

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

1977-01-01

189

Ability of Thermophilic Lactic Acid Bacteria To Produce Aroma Compounds from Amino Acids  

PubMed Central

Although a large number of key odorants of Swiss-type cheese result from amino acid catabolism, the amino acid catabolic pathways in the bacteria present in these cheeses are not well known. In this study, we compared the in vitro abilities of Lactobacillus delbrueckii subsp. lactis, Lactobacillus helveticus, and Streptococcus thermophilus to produce aroma compounds from three amino acids, leucine, phenylalanine, and methionine, under mid-pH conditions of cheese ripening (pH 5.5), and we investigated the catabolic pathways used by these bacteria. In the three lactic acid bacterial species, amino acid catabolism was initiated by a transamination step, which requires the presence of an ?-keto acid such as ?-ketoglutarate (?-KG) as the amino group acceptor, and produced ?-keto acids. Only S. thermophilus exhibited glutamate dehydrogenase activity, which produces ?-KG from glutamate, and consequently only S. thermophilus was capable of catabolizing amino acids in the reaction medium without ?-KG addition. In the presence of ?-KG, lactobacilli produced much more varied aroma compounds such as acids, aldehydes, and alcohols than S. thermophilus, which mainly produced ?-keto acids and a small amount of hydroxy acids and acids. L. helveticus mainly produced acids from phenylalanine and leucine, while L. delbrueckii subsp. lactis produced larger amounts of alcohols and/or aldehydes. Formation of aldehydes, alcohols, and acids from ?-keto acids by L. delbrueckii subsp. lactis mainly results from the action of an ?-keto acid decarboxylase, which produces aldehydes that are then oxidized or reduced to acids or alcohols. In contrast, the enzyme involved in the ?-keto acid conversion to acids in L. helveticus and S. thermophilus is an ?-keto acid dehydrogenase that produces acyl coenzymes A.

Helinck, Sandra; Le Bars, Dominique; Moreau, Daniel; Yvon, Mireille

2004-01-01

190

D-Amino Acids in Living Higher Organisms  

NASA Astrophysics Data System (ADS)

The homochirality of biological amino acids (L-amino acids) and of the RNA/DNA backbone (D-ribose) might have become established before the origin of life. It has been considered that D-amino acids and L-sugars were eliminated on the primitive Earth. Therefore, the presence and function of D-amino acids in living organisms have not been studied except for D-amino acids in the cell walls of microorganisms. However, D-amino acids were recently found in various living higher organisms in the form of free amino acids, peptides, and proteins. Free D-aspartate and D-serine are present and may have important physiological functions in mammals. D-amino acids in peptides are well known as opioid peptides and neuropeptides. In protein, D-aspartate residues increase during aging. This review deals with recent advances in the study of D-amino acids in higher organisms.

Fujii, Noriko

2002-04-01

191

Molecular Evolution of Plant AAP and LHT Amino Acid Transporters  

PubMed Central

Nitrogen is an essential mineral nutrient and it is often transported within living organisms in its reduced form, as amino acids. Transport of amino acids across cellular membranes requires proteins, and here we report the phylogenetic analysis across taxa of two amino acid transporter families, the amino acid permeases (AAPs) and the lysinehistidine-like transporters (LHTs). We found that the two transporter families form two distinct groups in plants supporting the concept that both are essential. AAP transporters seem to be restricted to land plants. They were found in Selaginella moellendorffii and Physcomitrella patens but not in Chlorophyte, Charophyte, or Rhodophyte algae. AAPs were strongly represented in vascular plants, consistent with their major function in phloem (vascular tissue) loading of amino acids for sink nitrogen supply. LHTs on the other hand appeared prior to land plants. LHTs were not found in chlorophyte algae Chlamydomonas reinhardtii and Volvox carterii. However, the characean alga Klebsormidium flaccidum encodes KfLHT13 and phylogenetic analysis indicates that it is basal to land plant LHTs. This is consistent with the hypothesis that characean algae are ancestral to land plants. LHTs were also found in both S. moellendorffii and P. patens as well as in monocots and eudicots. To date, AAPs and LHTs have mainly been characterized in Arabidopsis (eudicots) and these studies provide clues to the functions of the newly identified homologs.

Tegeder, Mechthild; Ward, John M.

2012-01-01

192

Molecular basis of essential amino acid transport from studies of insect nutrient amino acid transporters of the SLC6 family (NAT-SLC6)  

PubMed Central

Two protein families that represent major components of essential amino acid transport in insects have been identified. They are annotated as the SLC6 and SLC7 families of transporters according to phylogenetic proximity to characterized amino acid transporters (HUGO nomenclature). Members of these families have been identified as important apical and basolateral parts of transepithelial essential amino acid absorption in the metazoan alimentary canal. Synergistically, they play critical physiological roles as essential substrate providers to diverse metabolic processes, including generic protein synthesis. This review briefly clarifies the requirements for amino acid transport and a variety of amino acid transport mechanisms, including the aforementioned families. Further it focuses on the large group of Nutrient Amino acid Transporters (NATs), which comprise a recently identified subfamily of the Neurotransmitter Sodium Symporter family (NSS or SLC6). The first insect NAT, cloned from the caterpillar gut, has a broad substrate spectrum similar to mammalian B0 transporters. Several new NAT-SLC6 members have been characterized in an effort to explore mechanisms for the essential amino acid absorption in model dipteran insects. The identification and functional characterization of new B0-like and narrow specificity transporters of essential amino acids in fruit fly and mosquitoes leads to a fundamentally important insight: that NATs evolved and act together as the integrated active core of a transport network that mediates active alimentary absorption and systemic distribution of essential amino acids. This role of NATs is projected from the most primitive prokaryotes to the most complex metazoan organisms, and represents an interesting platform for unraveling the molecular evolution of amino acid transport and modeling amino acid transport disorders. The comparative study of NATs elucidates important adaptive differences between essential amino acid transportomes of invertebrate and vertebrate organisms, outlining a new possibility for selective targeting of essential amino acid absorption mechanisms to control medically and economically important arthropods and other invertebrate organisms.

Boudko, Dmitri Y.

2012-01-01

193

Molecular basis of essential amino acid transport from studies of insect nutrient amino acid transporters of the SLC6 family (NAT-SLC6).  

PubMed

Two protein families that represent major components of essential amino acid transport in insects have been identified. They are annotated as the SLC6 and SLC7 families of transporters according to phylogenetic proximity to characterized amino acid transporters (HUGO nomenclature). Members of these families have been identified as important apical and basolateral parts of transepithelial essential amino acid absorption in the metazoan alimentary canal. Synergistically, they play critical physiological roles as essential substrate providers to diverse metabolic processes, including generic protein synthesis. This review briefly clarifies the requirements for amino acid transport and a variety of amino acid transport mechanisms, including the aforementioned families. Further it focuses on the large group of Nutrient Amino acid Transporters (NATs), which comprise a recently identified subfamily of the Neurotransmitter Sodium Symporter family (NSS or SLC6). The first insect NAT, cloned from the caterpillar gut, has a broad substrate spectrum similar to mammalian B(0) transporters. Several new NAT-SLC6 members have been characterized in an effort to explore mechanisms for the essential amino acid absorption in model dipteran insects. The identification and functional characterization of new B(0)-like and narrow specificity transporters of essential amino acids in fruit fly and mosquitoes leads to a fundamentally important insight: that NATs evolved and act together as the integrated active core of a transport network that mediates active alimentary absorption and systemic distribution of essential amino acids. This role of NATs is projected from the most primitive prokaryotes to the most complex metazoan organisms, and represents an interesting platform for unraveling the molecular evolution of amino acid transport and modeling amino acid transport disorders. The comparative study of NATs elucidates important adaptive differences between essential amino acid transportomes of invertebrate and vertebrate organisms, outlining a new possibility for selective targeting of essential amino acid absorption mechanisms to control medically and economically important arthropods and other invertebrate organisms. PMID:22230793

Boudko, Dmitri Y

2012-04-01

194

Regulation of Sulfur Amino Acid Metabolism in Men in Response to Changes in Sulfur Amino Acid Intakes1,2  

Microsoft Academic Search

We showed previously that 64% of the total dietary sulfur amino acid (SAA) requirement could be supported by dietary cysteine (Cys). However, the observation of such a sparing effect may be affected by the dietary intakes of SAA provided. The aim of this study was to compare methionine (Met) metabolism and transsulfuration (TS) in five healthy men fed three different

Marco Di Buono; Linda J. Wykes; David E. C. Cole; Ronald O. Ball; Paul B. Pencharz

195

Gas-phase acidities of the 20 protein amino acids  

NASA Astrophysics Data System (ADS)

The gas-phase acidities of the 20 protein amino acids (PAAs) have been determined using an electrospray ionization-quadrupole ion trap instrument. Three different methods were used to determine both the absolute acidities and the relative acidity ordering of the PAAs. The extended kinetic method was used to determine absolute acidities for all 20 PAAs with substituted carboxylic acids and substituted phenols as reference acids. Acidities were obtained with an average uncertainty of 10 kJ/mol, which is large compared to some of the differences between amino acids with similar acidities. To determine the relative acidity ordering, single-reference kinetic method experiments were performed using both the reference acids from the absolute acidity studies and tryptophan and threonine as reference acids. Additional ordering information was obtained from kinetic method experiments in which proton-bound dimer ions comprising pairs of amino acids were generated and dissociated in the ion trap. The recommended acidity ordering is Gly < Ala < Pro < Val < Leu < Ile < Lys < Trp < Phe < Tyr < Met < Ser < Thr < Cys < Gln < Gln < Arg < Asn < His < Glu < Asp. Isodesmic acidity values were also obtained at the B3LYP/6-311++G**//B3LYP/6-31+G* level of theory with acetic acid as the reference acid. The theoretical acidities are in excellent agreement with the absolute acidities obtained from the extended kinetic method studies. The calculations predict that the preferred isomer for protonated cysteine and tyrosine is not a carboxylate anion, but rather a thiolate anion and a phenoxide anion, respectively.

Jones, Christopher M.; Bernier, Matthew; Carson, Erin; Colyer, Kathryn Ee; Metz, Rachel; Pawlow, Anna; Wischow, Emily D.; Webb, Ian; Andriole, Erica J.; Poutsma, John C.

2007-11-01

196

Evolution from amino acids - Lunar occurrence of their precursors.  

NASA Technical Reports Server (NTRS)

Review of the present state of experimentally based concepts of organic evolution from amino acids. Earlier studies of the synthesis of amino acid precursors from meteoritic material, lunar dust, and terrestrial lava are briefly summarized, and laboratory experiments in which polymers of amino acids were obtained either by direct heating of dry amino acids or by heating aqueous solutions of mixtures of amino acids are described. In particular, a process is described by which alpha-amino acids were made to react to form linear chains of proteinoids. It is concluded that a proteinoid microsystem was a common ancestor of all life on earth.

Fox, S. W.

1972-01-01

197

Chemical Properties of Amino Acids and Identification of Unknown Amino Acids  

NSDL National Science Digital Library

This resource describes two related laboratory exercises on the chemical properties and identification of amino acids (the building blocks of proteins). Detailed pre-lab assignments and guidelines for students' laboratory reports are provided.

Karen Sprague (University of Oregon;); Carl Stiefbold (University of Oregon;); Sam Donovan (University of Oregon;)

1996-01-01

198

Amino Acid Transport into Cultured Tobacco Cells  

PubMed Central

The effects of calcium ions on lysine transport into cultured Wisconsin-38 tobacco cells were examined. In the presence of calcium, lysine was transported at a relatively low rate for 30 to 40 minutes followed by a period of increasing rates and subsequent stabilization at a higher rate after 2 to 3 hours. In the absence of calcium, transport was uniformly low. Time-dependent stimulation of lysine transport rate was observed after the cells had been preincubated in calcium-containing media. Similar treatments also resulted in the stimulated uptake of a variety of other amino acids, organic compounds, and sulfate. The stimulation of lysine uptake was apparently not due to nutrient starvation. Lysine transport was not stimulated in a time-dependent fashion by K+, La3+, Mg2+, or Mn2+. Cells with stimulated transport rates continued to exhibit high rates when washed with calcium-containing media followed by transport in calcium-containing media. All other cation wash treatments were inhibitory, although magnesium treatments resulted in partial preservation of stimulated transport rates. Cycloheximide inhibited the calcium/time-dependent stimulation of lysine transport and caused the stimulated rate to decay. The initial experimental treatments or the culture conditions may represent some form of shock that alters the membrane transport mechanism, thus reducing transport. The observed calcium/time-dependent stimulation may require protein synthesis and represents damage repair.

Harrington, H. Michael; Berry, Sandra L.; Henke, Randolph R.

1981-01-01

199

[Secretion of endogenous amino acids in the gastrointestinal tract and amino acid resorption in the swine].  

PubMed

A trial was performed with 2 fistula pigs (each with 2 fistulas, one located about 30 cm below the pyloric orifice and the other at the end of the small intestine). Animal A received a casein diet containing 14% crude protein for a period of 2 weeks before the tracer amino acid was administered. Animal B received the same diet for a period of 10 days and was then fed a diet (at the same protein level) containing gluten as sole protein source. The two tracer amino acids, 14C-U-L-leucine and 3H-4,5-(N)-L-lysine, were injected intravenously. The passage rates for dry matter, organic matter and N measured at the beginning of the small intestine were higher than the rate of intake. The rate of passage of amino acids was also found to be increased relative to the rate of intake. In general, this increase involved the non-essential amino acids to a much larger extent. A considerable proportion of the amino acids passing into the large intestine is not excreted with the faeces but is probably converted in catabolic processes. It is for this reason that any values for the efficiency of amino acid absorption calculated on the basis of data on the faecal excretion of amino acids will not provide conclusive evidence for the availability of dietary amino acids in processes of the intermediate metabolism. The rate of secretion of 3H and 14C radioactivity into the digesta of the small intestine was found to increase rapidly within 1-2 hrs after administration of the tracer amino acids. The 14C radioactivity detected was found to be almost exclusively derived from 14C leucine while only about 60% of the 3H activity found in the digesta of fistula I were shown to be bound to lysine. Labelled lysine and leucine (of endogenic origin) are absorbed into the small intestine at a slower rate (i.e. endogenic proteins are less efficiently digested) than the non-radioactive amino acids (of exogenic origin) so that a process of concentration of endogenic amino acids is observed towards the end of the small intestine. PMID:962584

Zebrowska, T; Simon, O; Mnchmeyer, R; Bergner, H

1976-02-01

200

Thin-Layer Separation of Citric Acid Cycle Intermediates, Lactic Acid, and the Amino Acid Taurine.  

National Technical Information Service (NTIS)

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 ...

R. T. Riley M. C. Mix

1979-01-01

201

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

Microsoft Academic Search

Transport of phenylalanine and lysine into the brain was measured in 4-wk streptozotocin-diabetic rats to assess the effect on the neutral and basic amino acid transport systems at the blood-brain barrier. Amino acid concentrations in plasma and brain were also measured. Regional permeability-times-surface area (PS) products and influx were determined using a continuous infusion method and quantitative autoradiography. The PS

A. M. Mans; M. R. DeJoseph; Davis D. W; R. A. Hawkins

1987-01-01

202

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

203

Determining important regulatory relations of amino acids from dynamic network analysis of plasma amino acids  

Microsoft Academic Search

The changes in the concentrations of plasma amino acids do not always follow the flow-based metabolic pathway network. We\\u000a have previously shown that there is a control-based network structure among plasma amino acids besides the metabolic pathway\\u000a map. Based on this network structure, in this study, we performed dynamic analysis using time-course data of the plasma samples\\u000a of rats fed

Nahoko Shikata; Yukihiro Maki; Masahiko Nakatsui; Masato Mori; Yasushi Noguchi; Shintaro Yoshida; Michio Takahashi; Nobuo Kondo; Masahiro Okamoto

2010-01-01

204

Plant amino acid-derived vitamins: biosynthesis and function.  

PubMed

Vitamins are essential organic compounds for humans, having lost the ability to de novo synthesize them. Hence, they represent dietary requirements, which are covered by plants as the main dietary source of most vitamins (through food or livestock's feed). Most vitamins synthesized by plants present amino acids as precursors (B1, B2, B3, B5, B7, B9 and E) and are therefore linked to plant nitrogen metabolism. Amino acids play different roles in their biosynthesis and metabolism, either incorporated into the backbone of the vitamin or as amino, sulfur or one-carbon group donors. There is a high natural variation in vitamin contents in crops and its exploitation through breeding, metabolic engineering and agronomic practices can enhance their nutritional quality. While the underlying biochemical roles of vitamins as cosubstrates or cofactors are usually common for most eukaryotes, the impact of vitamins B and E in metabolism and physiology can be quite different on plants and animals. Here, we first aim at giving an overview of the biosynthesis of amino acid-derived vitamins in plants, with a particular focus on how this knowledge can be exploited to increase vitamin contents in crops. Second, we will focus on the functions of these vitamins in both plants and animals (and humans in particular), to unravel common and specific roles for vitamins in evolutionary distant organisms, in which these amino acid-derived vitamins play, however, an essential role. PMID:24368523

Miret, Javier A; Munn-Bosch, Sergi

2014-04-01

205

Amino acids of the Murchison meteorite. I - Six carbon acyclic primary alpha-amino alkanoic acids  

NASA Technical Reports Server (NTRS)

Six of the seven chain isomers of six-carbon acyclic primary alpha-amino alkanoic acids (leucine isomers) have been either identified or confirmed in hot-water extracts of the Murchison meteorite using combined gas chromatography-mass spectrometry (GC-MS) and ion exchange chromatography. 2-Amino-2-ethylbutyric acid, 2-amino-2,3-dimethylbutyric acid, pseudoleucine, and 2-methylnorvaline were positively identified by GC-MS. These amino acids have not been previously reported to occur in natural materials and may be uniquely meteoritic in origin. The presence of leucine and isoleucine (including the diastereoisomer, alloisoleucine) was confirmed. Peaks corresponding to norleucine were seen by ion-exchange and gas chromatography but characteristic mass spectra were not obtained. The alpha-branched chain isomers in this series are quantitatively the most significant. These results are compared with literature data on amino acid synthesis by electrical discharge and Fischer-Tropsch-type catalysis. Neither model system produces an amino acid suite that is completely comparable to that found in the Murchison meteorite.

Cronin, J. R.; Gandy, W. E.; Pizzarello, S.

1981-01-01

206

Amino acids of the Murchison meteorite: I. Six carbon acyclic primary alpha-amino alkanoic acids.  

PubMed

Six of the seven chain isomers of six-carbon acyclic primary alpha-amino alkanoic acids (leucine isomers) have been either identified or confirmed in hot-water extracts of the Murchison meteorite using combined gas chromatography-mass spectrometry (GC-MS) and ion exchange chromatography. 2-Amino-2-ethylbutyric acid, 2-amino-2,3-dimethylbutyric acid, pseudoleucine, and 2-methylnorvaline were positively identified by GC-MS. These amino acids have not been previously reported to occur in natural materials and may be uniquely meteoritic in origin. The presence of leucine and isoleucine (including the diastereoisomer, alloisoleucine) was confirmed. Peaks corresponding to norleucine were seen by ion-exchange and gas chromatography but characteristic mass spectra were not obtained. The alpha-branched chain isomers in this series are quantitatively the most significant. These results are compared with literature data on amino acid synthesis by electrical discharge and Fischer-Tropsch-type catalysis. Neither model system produces an amino acids suite that is completely comparable to that found in the Murchison meteorite. PMID:7277509

Cronin, J R; Gandy, W E; Pizzarello, S

1981-01-01

207

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

208

Peptidases and amino acid catabolism in lactic acid bacteria  

Microsoft Academic Search

The conversion of peptides to free amino acids and their subsequent utilization is a central metabolic activity in prokaryotes. At least 16 peptidases from lactic acid bacteria (LAB) have been characterized biochemically and\\/or genetically. Among LAB, the peptidase systems of Lactobacillus helveticus and Lactococcus lactis have been examined in greatest detail. While there are homologous enzymes common to both systems,

Jeffrey E. Christensen; Edward G. Dudley; Jeffrey A. Pederson; James L. Steele

1999-01-01

209

40 CFR 721.10126 - Alkyl amino substituted triazine amino substituted benezenesulfonic acid reaction product with...  

Code of Federal Regulations, 2010 CFR

...substituted triazine amino substituted benezenesulfonic acid reaction product with naphthalenesulfonato azo substituted phenyl azo substituted benzenesulfonic acid copper compound (generic). 721.10126 Section 721.10126 Protection...

2010-07-01

210

A genetically encoded fluorescent amino acid  

PubMed Central

The ability to introduce fluorophores selectively into proteins provides a powerful tool to study protein structure, dynamics, localization, and biomolecular interactions both in vitro and in vivo. Here, we report a strategy for the selective and efficient biosynthetic incorporation of a low-molecular-weight fluorophore into proteins at defined sites. The fluorescent amino acid 2-amino-3-(5-(dimethylamino)naphthalene-1-sulfonamide)propanoic acid (dansylalanine) was genetically encoded in Saccharomyces cerevisiae by using an amber nonsense codon and corresponding orthogonal tRNA/aminoacyl-tRNA synthetase pair. This environmentally sensitive fluorophore was selectively introduced into human superoxide dismutase and used to monitor unfolding of the protein in the presence of guanidinium chloride. The strategy described here should be applicable to a number of different fluorophores in both prokaryotic and eukaryotic organisms, and it should facilitate both biochemical and cellular studies of protein structure and function.

Summerer, Daniel; Chen, Shuo; Wu, Ning; Deiters, Alexander; Chin, Jason W.; Schultz, Peter G.

2006-01-01

211

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

212

Amino Acid Composition of Crystalline Botulinum Toxin, Type A.  

National Technical Information Service (NTIS)

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

D. Stefanye

1965-01-01

213

Amino Acids in Nectar Enhance Longevity of Female Culex quinquefasciatus.  

National Technical Information Service (NTIS)

Culex mosquitoes feed on a wide range of nectars consisting of mostly carbohydrates and amino acids however, little is known about the utilization and effects of these different carbohydrates and their accompanying amino acids on longevity. Culex quinquef...

D. A. Hahn E. M. Vrzal S. A. Allan

2010-01-01

214

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.

2014-01-01

215

Identification of a novel system L amino acid transporter structurally distinct from heterodimeric amino acid transporters.  

PubMed

A cDNA that encodes a novel Na+-independent neutral amino acid transporter was isolated from FLC4 human hepatocarcinoma cells by expression cloning. When expressed in Xenopus oocytes, the encoded protein designated LAT3 (L-type amino acid transporter 3) transported neutral amino acids such as l-leucine, l-isoleucine, l-valine, and l-phenylalanine. The LAT3-mediated transport was Na+-independent and inhibited by 2-aminobicyclo[2.2.1]heptane-2-carboxylic acid, consistent with the properties of system L. Distinct from already known system L transporters LAT1 and LAT2, which form heterodimeric complex with 4F2 heavy chain, LAT3 was functional by itself in Xenopus oocytes. The deduced amino acid sequence of LAT3 was identical to the gene product of POV1 reported as a prostate cancer-up-regulated gene whose function was not determined, whereas it did not exhibit significant similarity to already identified transporters. The Eadie-Hofstee plots of LAT3-mediated transport were curvilinear, whereas the low affinity component is predominant at physiological plasma amino acid concentration. In addition to amino acid substrates, LAT3 recognized amino acid alcohols. The transport of l-leucine was electroneutral and mediated by a facilitated diffusion. In contrast, l-leucinol, l-valinol, and l-phenylalaninol, which have a net positive charge induced inward currents under voltage clamp, suggesting these compounds are transported by LAT3. LAT3-mediated transport was inhibited by the pretreatment with N-ethylmaleimide, consistent with the property of system L2 originally characterized in hepatocyte primary culture. Based on the substrate selectivity, affinity, and N-ethylmaleimide sensitivity, LAT3 is proposed to be a transporter subserving system L2. LAT3 should denote a new family of organic solute transporters. PMID:12930836

Babu, Ellappan; Kanai, Yoshikatsu; Chairoungdua, Arthit; Kim, Do Kyung; Iribe, Yuji; Tangtrongsup, Sahatchai; Jutabha, Promsuk; Li, Yuewei; Ahmed, Nesar; Sakamoto, Shinichi; Anzai, Naohiko; Nagamori, Seishi; Endou, Hitoshi

2003-10-31

216

Amino acids: metabolism, functions, and nutrition  

Microsoft Academic Search

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

Guoyao Wu

2009-01-01

217

A search for extraterrestrial amino acids in carbonaceous Antarctic micrometeorites.  

PubMed

Antarctic micrometeorites (AMMs) in the 100-400 microns size range are the dominant mass fraction of extraterrestrial material accreted by the Earth today. A high performance liquid chromatography (HPLC) based technique exploited at the limits of sensitivity has been used to search for the extraterrestrial amino acids alpha-aminoisobutyric acid (AIB) and isovaline in AMMs. Five samples, each containing about 30 to 35 grains, were analyzed. All the samples possess a terrestrial amino acid component, indicated by the excess of the L-enantiomers of common protein amino acids. In only one sample (A91) was AIB found to be present at a level significantly above the background blanks. The concentration of AIB (approximately 280 ppm), and the AIB/isovaline ratio (> or = 10), in this sample are both much higher than in CM chondrites. The apparently large variation in the AIB concentrations of the samples suggests that AIB may be concentrated in rare subset of micrometeorites. Because the AIB/isovaline ratio in sample A91 is much larger than in CM chondrites, the synthesis of amino acids in the micrometeorite parent bodies might have involved a different process requiring an HCN-rich environment, such as that found in comets. If the present day characteristics of the meteorite and micrometeorite fluxes can be extrapolated back in time, then the flux of large carbonaceous micrometeorites could have contributed to the inventory of prebiotic molecules on the early Earth. PMID:9742723

Brinton, K L; Engrand, C; Glavin, D P; Bada, J L; Maurette, M

1998-10-01

218

Expanded cellular amino Acid pools containing phosphoserine, phosphothreonine, and phosphotyrosine.  

PubMed

Adding nonstandard amino acids to the genetic code of E. coli expands the chemical and biological functional space for proteins. This is accomplished with engineered, orthogonal aminoacyl-tRNA synthetase and tRNA pairs that require a nonstandard amino acid in sufficient intracellular quantities to support protein synthesis. While cotranslational insertion of phosphoserine into proteins has been accomplished, conditions that modulate intracellular phosphoamino acid concentrations are still poorly understood. Here we used genetic and metabolic engineering to increase the free intracellular levels of phosphoserine in E. coli. We show that deletion of the phosphoserine phosphatase serB elevates the intracellular levels of phosphoserine within ranges comparable to those of standard amino acids. These new conditions improved insertion of phosphoserine into recombinant proteins. Surprisingly, we also observed dramatic increases in intracellular levels of phosphothreonine and phosphotyrosine when WT cells were grown in LB with supplemented phosphothreonine and serB deficient cells were grown in low phosphate media with supplemented phosphotyrosine, respectively. These findings remove a major barrier for further expansion of the genetic code with additional phosphorylated amino acids. PMID:24646179

Steinfeld, Justin B; Aerni, Hans R; Rogulina, Svetlana; Liu, Yuchen; Rinehart, Jesse

2014-05-16

219

Amino Acids as Metabolic Substrates during Cardiac Ischemia  

PubMed Central

The heart is well known as a metabolic omnivore in that it is capable of consuming fatty acids, glucose, ketone bodies, pyruvate, lactate, amino acids and even its own constituent proteins, in order of decreasing preference. The energy from these substrates supports not only mechanical contraction, but also the various transmembrane pumps and transporters required for ionic homeostasis, electrical activity, metabolism and catabolism. Cardiac ischemia for example, due to compromise of the coronary vasculature or end-stage heart failure will alter both electrical and metabolic activity. While the effects of myocardial ischemia on electrical propagation and stability have been studied in depth, the effects of ischemia on metabolic substrate preference has not been fully appreciated: oxygen deprivation during ischemia will significantly alter the relative ability of the heart to utilize each of these substrates. Although changes in cardiac metabolism are understood to be an underlying component in almost all cardiac myopathies, the potential contribution of amino acids in maintaining cardiac electrical conductance and stability during ischemia is underappreciated. Despite clear evidence that amino acids exert cardioprotective effects in ischemia and other cardiac disorders, their role in the metabolism of the ischemic heart has yet to be fully elucidated. This review synthesizes the current literature of the metabolic contribution of amino acids during ischemia by analyzing relevant historical and recent research.

Drake, Kenneth J.; Sidorov, Veniamin Y.; McGuinness, Owen P.; Wasserman, David H.; Wikswo, John P.

2013-01-01

220

Structure and Function of Cationic Amino Acid Transporters (CATs)  

Microsoft Academic Search

The CAT proteins (CAT for cationic amino acid transporter) are amongst the first mammalian amino acid transporters identified\\u000a on the molecular level and seem to be the major entry path for cationic amino acids in most cells. However, CAT proteins mediate\\u000a also efflux of their substrates and thus may also deplete cells from cationic amino acids under certain circumstances. The

E. I. Closs; J.-P. Boissel; A. Habermeier; A. Rotmann

2006-01-01

221

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.

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

2014-01-01

222

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

Microsoft Academic Search

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

Philip NEWSHOLME; Lorraine BRENNAN; Blanca RUBI; Pierre MAECHLER

2005-01-01

223

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

224

Amino acid and carnitine supplementation in haemodialysed children  

Microsoft Academic Search

Plasma carnitine, amino acids and lipids levels were studied in ten uraemic children treated with haemodialysis and given amino acid supplementation with and without carnitine. As carnitine is synthesised from lysine and methionine and has a significant influence on lipid metabolism, the relationship between these was examined. Amino acid supplementation (0.25 g\\/kg body weight) was started with the intention of

J. Zachwieja; M. Duran; J. A. Joles; P. J. Allers; D. Hurk; J. J. Frankhuisen; R. A. M. G. Donckerwolcke

1994-01-01

225

Amino Acids in Gut Contents During Digestion in the Dog  

Microsoft Academic Search

Analyses of alimentary tract contents for free amino acids demonstrated that various test meals yielded similar amino acid mixtures in the small intestine (Nas- set et al., '55). Gastric and duodenal con tents arising from a test meal protein of unusual amino acid composition, such as zein, were usually identifiable. Jejunal and ileal contents could not be characterized in this

E. S. NASSET

226

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蚓, 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

227

Bioavailable amino acids in sediments: A biomimetic, kinetics based approach  

Microsoft Academic Search

We developed a biomimetic approach, based on direct incubation with proteolytic enzymes, to measure bioavailable amino acids in sediments. The kinetics of release of monomers and oligopeptides, which are amenable to absorption by cells, is measured as either individual or total amino acids. Microbial proteases incubated with fresh sediments yield amino acids at a similar rate as gut juices from

LAWRENCE M. MAYER; LINDA L. SCHICK; THOMAS SAWYER; CRAIG J. PLANTE; PETER A. JUMARS; ROBERT L. SELF

1995-01-01

228

Transport of acidic amino acids by human jejunal brush-border membrane vesicles  

SciTech Connect

This study characterizes the transport of radiolabeled acidic amino acids into brush-border membrane vesicles prepared from human jejunum. The uptakes of L-glutamic, L-aspartic, and D-aspartic acids were stimulated by a Na/sup +/ gradient. Concentrative uptake (resulting in an overshoot phenomenon) of these dicarboxylic amino acids occurred when there was an outward K/sup +/ gradient. In addition, increasing K/sup +/ gradients resulted in enhanced uptake of L-glutamic acid. This K/sup +/ requirement is somewhat specific as Rb/sup +/ and Cs/sup +/ could enhance uptake to a limited extent, whereas Li/sup +/ and choline/sup +/ showed no enhancement. The presence of a K/sup +/ gradient did not affect the affinity of the carrier system for L-glutamic acid but it did increase the V/sub max/. The presence of extravesicular anions having differing membrane permeabilities did not altar L-glutamic acid uptake indicating an absence of an effect of membrane potential on the transport process. Finally, the human transport system for L-glutamic acid appears to be specific for acidic amino acids as demonstrated by inhibition studies. The studies demonstrate a transport system in human jejunum specific for acidic amino acids that is energized by an inward Na/sup +/ gradient and an outward K/sup +/ gradient.

Rajendran, V.M.; Harig, J.M.; Adams, M.B.; Ramaswamy, K.

1987-01-01

229

Specificity of amino acid regulated gene expression: analysis of genes subjected to either complete or single amino acid deprivation  

Microsoft Academic Search

Amino acid deprivation activates the amino acid response (AAR) pathway that enhances transcription of genes containing an\\u000a amino acid response element (AARE). The present data reveal a quantitative difference in the response to deprivation of individual\\u000a amino acids. The AAR leads to increased eukaryotic initiation factor 2? (eIF2?) phosphorylation and ATF4 translation. When\\u000a HepG2 cells were deprived of an individual

S. S. Palii; C. E. Kays; C. Deval; A. Bruhat; P. Fafournoux; M. S. Kilberg

2009-01-01

230

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, Jos Lino; Casta嚧n Gonz嫮ez, Jorge Alberto; Estrada, Miguel Arias

2014-01-01

231

Hair and amino acids: the interactions and the effects.  

PubMed

The interaction and the function of some amino acids in hair care applications are discussed. When amino acids are applied to hair in the form of simple aqueous solution, uptake of the amino acids is mainly controlled by ionic equilibrium. When amino acids were incorporated in a hair conditioner, the result was quite different, suggesting the importance of interaction between the amino acids and the cationic surfactants. Uptake of pyrrolidone carboxylic acid (PCA), a derivative of glutamic acid, is enhanced by combining with arginine, an amino with strong affinity towards hair. Effects of some amino acids on bleached/dyed hair are described. A hair conditioner incorporated with alanine improves hair surface hydrophobicity of bleach-damaged hair. Histidine and phenylalanine improve tensile strength. PCA was proved to be effective to improve color-retention of dyed hair. PMID:17728935

Oshimura, Eiko; Abe, Hiroshi; Oota, Rina

2007-01-01

232

Synthesis of N-kojic-amino acid and N-kojic-amino acid-kojiate and their tyrosinase inhibitory activity  

Microsoft Academic Search

Ten amino acid derivatives of kojic acid were synthesized to improve the tyrosinase inhibitory activity of kojic acid. Almost all derivatives showed stronger activities than kojic acid, and in general, N-kojic-amino acid-kojiate was found to have a higher inhibitory potency than N-kojic-amino acid. Among them, the N-kojic-L-phenylalanyl kojiate was the strongest inhibitor and its IC50 value was 1\\/380 that for

Yoshikane Kobayashi; Hiroshi Kayahara; Koji Tadasa; Hiroshi Tanaka

1996-01-01

233

Competitive Inhibition of Amino Acid Uptake Suppresses Chlamydial Growth: Involvement of the Chlamydial Amino Acid Transporter BrnQ  

Microsoft Academic Search

Chlamydiaceae are obligate intracellular bacterial pathogens that strictly depend on host metabolites, such as nucleotides, lipids, and amino acids. Depletion of amino acids in cell culture media results in abnormal chlamydial development in vitro. Surprisingly, enrichment of certain amino acids also retards chlamydial growth. Our experiments revealed that the antichlamydial effects are largely independent of changes in the host cell

Peter R. Braun; Hesham Al-Younes; Joscha Gussmann; Jeannette Klein; Erwin Schneider; Thomas F. Meyer

2008-01-01

234

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

PubMed

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

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

2013-09-25

235

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

236

Amino acid compositional shifts during streptophyte transitions to terrestrial habitats.  

PubMed

Across the streptophyte lineage, which includes charophycean algae and embryophytic plants, there have been at least four independent transitions to the terrestrial habitat. One of these involved the evolution of embryophytes (bryophytes and tracheophytes) from a charophycean ancestor, while others involved the earliest branching lineages, containing the monotypic genera Mesostigma and Chlorokybus, and within the Klebsormidiales and Zygnematales lineages. To overcome heat, water stress, and increased exposure to ultraviolet radiation, which must have accompanied these transitions, adaptive mechanisms would have been required. During periods of dehydration and/or desiccation, proteomes struggle to maintain adequate cytoplasmic solute concentrations. The increased usage of charged amino acids (DEHKR) may be one way of maintaining protein hydration, while increased use of aromatic residues (FHWY) protects proteins and nucleic acids by absorbing damaging UV, with both groups of residues thought to be important for the stabilization of protein structures. To test these hypotheses we examined amino acid sequences of orthologous proteins representing both mitochondrion- and plastid-encoded proteomes across streptophytic lineages. We compared relative differences within categories of amino acid residues and found consistent patterns of amino acid compositional fluxuation in extra-membranous regions that correspond with episodes of terrestrialization: positive change in usage frequency for residues with charged side-chains, and aromatic residues of the light-capturing chloroplast proteomes. We also found a general decrease in the usage frequency of hydrophobic, aliphatic, and small residues. These results suggest that amino acid compositional shifts in extra-membrane regions of plastid and mitochondrial proteins may represent biochemical adaptations that allowed green plants to colonize the land. PMID:21153633

Jobson, Richard W; Qiu, Yin-Long

2011-02-01

237

Urinary Amino Acid Analysis: A Comparison of iTRAQ(R)-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 7.275.22, 21.1810.94, and 18.3414.67, respectively. Corresponding values for 13 amino acids determined in a second batch of 144 urine specimens measured in duplicate or triplicate were 8.395.35, 6.233.84, and 35.3729.42. 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.

Kaspar, Hannelore; Dettmer, Katja; Chan, Queenie; Daniels, Scott; Nimkar, Subodh; Daviglus, Martha L.; Stamler, Jeremiah; Elliott, Paul; Oefner, Peter J.

2009-01-01

238

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

239

Phenotypic and Genotypic Analysis of Amino Acid Auxotrophy in Lactobacillus helveticus CNRZ 32?  

PubMed Central

The conversion of amino acids into volatile and nonvolatile compounds by lactic acid bacteria in cheese is thought to represent the rate-limiting step in the development of mature flavor and aroma. Because amino acid breakdown by microbes often entails the reversible action of enzymes involved in biosynthetic pathways, our group investigated the genetics of amino acid biosynthesis in Lactobacillus helveticus CNRZ 32, a commercial cheese flavor adjunct that reduces bitterness and intensifies flavor notes. Most lactic acid bacteria are auxotrophic for several amino acids, and L. helveticus CNRZ 32 requires 14 amino acids. The reconstruction of amino acid biosynthetic pathways from a draft-quality genome sequence for L. helveticus CNRZ 32 revealed that amino acid auxotrophy in this species was due primarily to gene absence rather than point mutations, insertions, or small deletions, with good agreement between gene content and phenotypic amino acid requirements. One exception involved the phenotypic requirement for Asp (or Asn), which genome predictions suggested could be alleviated by citrate catabolism. This prediction was confirmed by the growth of L. helveticus CNRZ 32 after the addition of citrate to a chemically defined medium that lacked Asp and Asn. Genome analysis also predicted that L. helveticus CNRZ 32 possessed ornithine decarboxylase activity and would therefore catalyze the conversion of ornithine to putrescine, a volatile biogenic amine. However, experiments to confirm ornithine decarboxylase activity in L. helveticus CNRZ 32 by the use of several methods were unsuccessful, which indicated that this bacterium likely does not contribute to putrescine production in cheese.

Christiansen, Jason K.; Hughes, Joanne E.; Welker, Dennis L.; Rodriguez, Beatriz T.; Steele, James L.; Broadbent, Jeff R.

2008-01-01

240

Organic geochemistry of amino acids: Precambrian to recent  

SciTech Connect

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

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

1985-01-01

241

Gut luminal endogenous protein: implications for the determination of ileal amino acid digestibility in humans.  

PubMed

The true ileal digestibility assay provides the most informative measure of digestibility to assess bioavailability of amino acids in foods for humans. To determine 'true' estimates of ileal amino acid digestibility, requires that endogenous amino acids present in digesta at the terminal ileum be quantified. The amounts of endogenous amino acids in ileal digesta can be determined after feeding an animal or human a protein-free diet (traditional approach) or by various methods after giving a protein-containing diet. When the protein-free method has been applied with adult human subjects an overall mean value (three separate studies) for endogenous ileal nitrogen flow of 800 mg N/d has been reported. This value is considerably lower than a comparable value obtained after feeding protein of 1852 mg N/d (mean of four separate studies), and thus endogenous ileal N and amino acids should be measured under conditions of protein alimentation. There is some confusion concerning the terminology used to define digestibility, with the term "true" digestibility having different adopted meanings. Here, true amino acid digestibility is defined as apparent amino acid digestibility corrected for the basal amino acid losses determined after giving either a protein-free or a protein-containing diet. Basal losses should be determined at a defined dry-matter and protein intake. The protein-free diet approach to determining endogenous amino acids is considered unphysiological and basal losses refer to ileal endogenous amino acid flows associated with digesta dry-matter flow, and not including "specific" effects of dietary factors such as non starch polysaccharides and anti nutritional factors. Arguments are advanced that the enzyme hydrolysed protein/ultra filtration method may be suitable for routine application with a cannulated pig model, to obtain physiologically-valid basal estimates of ileal endogenous amino acids to allow calculation of true ileal amino acid digestibility in the pig, and then prediction (via statistical relationships) of true coefficients of amino acid digestibility in humans. PMID:23107536

Moughan, Paul J; Rutherfurd, Shane M

2012-08-01

242

Paralogous chemoreceptors mediate chemotaxis towards protein amino acids and the non-protein amino acid gamma-aminobutyrate (GABA).  

PubMed

The paralogous receptors PctA, PctB and PctC of Pseudomonas aeruginosa were reported to mediate chemotaxis to amino acids, intermediates of amino acid metabolism and chlorinated hydrocarbons. We show that the recombinant ligand binding regions (LBRs) of PctA, PctB and PctC bind 17, 5 and 2 l-amino acids respectively. In addition, PctC-LBR recognized GABA but not any other structurally related compound. l-Gln, one of the three amino acids that is not recognized by PctA-LBR, was the most tightly binding ligand to PctB suggesting that PctB has evolved to mediate chemotaxis primarily towards l-Gln. Bacteria were efficiently attracted to l-Gln and GABA, but mutation of pctB and pctC, respectively, abolished chemoattraction. The physiological relevance of taxis towards GABA is proposed to reside in an interaction with plants. LBRs were predicted to adopt double PDC (PhoQ/DcuS/CitA) like structures and site-directed mutagenesis studies showed that ligands bind to the membrane-distal module. Analytical ultracentrifugation studies have shown that PctA-LBR and PctB-LBR are monomeric in the absence and presence of ligands, which is in contrast to the enterobacterial receptors that require sensor domain dimers for ligand recognition. PMID:23650915

Rico-Jim幯ez, Miriam; Mu隳z-Mart璯ez, Francisco; Garc燰-Fontana, Cristina; Fernandez, Matilde; Morel, Bertrand; Ortega, Alvaro; Ramos, Juan Luis; Krell, Tino

2013-06-01

243

Amino Acid Metabolism of Pea Leaves  

PubMed Central

Short term (2-hour) incorporation of nitrogen from nitrate, glutamine, or asparagine was studied by supplying them as unlabeled (14N) tracers to growing pea (Pisum sativum L.) leaves, which were previously labeled with 15N, and then following the elimination of 15N from various amino components of the tissue. Most components had active and inactive pools. Ammonia produced from nitrate was assimilated through the amide group of glutamine. When glutamine was supplied, its nitrogen was rapidly transferred to glutamic acid, asparagine, and other products, and there was some transfer to ammonia. Nitrogen from asparagine was widely distributed into ammonia and amino compounds. There was a rapid direct transfer to glutamine, which did not appear to involve free ammonia. Alanine nitrogen could be derived directly from asparagine, probably by transamination. Homoserine was synthesized in substantial amounts from all three nitrogen sources. Homoserine appears to derive nitrogen more readily from asparagine than from free aspartic acid. A large proportion of the pool of ?-aminobutyric acid turned over, and was replenished with nitrogen from all three supplied sources.

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

1977-01-01

244

Biosynthesis of amino acids in Clostridium pasteurianum  

PubMed Central

1. Clostridium pasteurianum was grown on a synthetic medium with the following carbon sources: (a) 14C-labelled glucose, alone or with unlabelled aspartate or glutamate, or (b) unlabelled glucose plus 14C-labelled aspartate, glutamate, threonine, serine or glycine. The incorporation of 14C into the amino acids of the cell protein was examined. 2. In both series of experiments carbon from exogenous glutamate was incorporated into proline and arginine; carbon from aspartate was incorporated into glutamate, proline, arginine, lysine, methionine, threonine, isoleucine, glycine and serine. Incorporations from the other exogenous amino acids indicated the metabolic sequence: aspartate ? threonine ? glycine ? serine. 3. The following activities were demonstrated in cell-free extracts of the organism: (a) the formation of aspartate by carboxylation of phosphoenolpyruvate or pyruvate, followed by transamination; (b) the individual reactions of the tricarboxylic acid route to 2-oxoglutarate from oxaloacetate; glutamate dehydrogenase was not detected; (c) the conversion of aspartate into threonine via homoserine; (d) the conversion of threonine into glycine by a constitutive threonine aldolase; (e) serine transaminase, phosphoserine transaminase, glycerate dehydrogenase and phosphoglycerate dehydrogenase. This last activity was abnormally high. 4. The combined evidence indicates that in C. pasteurianum the biosynthetic role of aspartate and glutamate is generally similar to that in aerobic and facultatively aerobic organisms, but that glycine is synthesized from glucose via aspartate and threonine.

Dainty, R. H.; Peel, J. L.

1970-01-01

245

Review: Taurine: A "very essential" amino acid  

PubMed Central

Taurine is an organic osmolyte involved in cell volume regulation, and provides a substrate for the formation of bile salts. It plays a role in the modulation of intracellular free calcium concentration, and although it is one of the few amino acids not incorporated into proteins, taurine is one of the most abundant amino acids in the brain, retina, muscle tissue, and organs throughout the body. Taurine serves a wide variety of functions in the central nervous system, from development to cytoprotection, and taurine deficiency is associated with cardiomyopathy, renal dysfunction, developmental abnormalities, and severe damage to retinal neurons. All ocular tissues contain taurine, and quantitative analysis of ocular tissue extracts of the rat eye revealed that taurine was the most abundant amino acid in the retina, vitreous, lens, cornea, iris, and ciliary body. In the retina, taurine is critical for photoreceptor development and acts as a cytoprotectant against stress-related neuronal damage and other pathological conditions. Despite its many functional properties, however, the cellular and biochemical mechanisms mediating the actions of taurine are not fully known. Nevertheless, considering its broad distribution, its many cytoprotective attributes, and its functional significance in cell development, nutrition, and survival, taurine is undoubtedly one of the most essential substances in the body. Interestingly, taurine satisfies many of the criteria considered essential for inclusion in the inventory of neurotransmitters, but evidence of a taurine-specific receptor has yet to be identified in the vertebrate nervous system. In this report, we present a broad overview of the functional properties of taurine, some of the consequences of taurine deficiency, and the results of studies in animal models suggesting that taurine may play a therapeutic role in the management of epilepsy and diabetes.

Shen, Wen

2012-01-01

246

Amino acids, precursors for cationic and anionic intercalation synthesis and characterization of amino acid pillared materials  

NASA Astrophysics Data System (ADS)

The preparation and characterization of amino acid pillared materials are reported in this contribution. Host substances were Na-montmorillonite for cationic and hydrotalcite for anionic pillaring. Guest molecules were L-phenylalanine and L-tyrosine. The pillared materials were characterized by powder X-ray diffraction, BET measurements and FT-IR spectroscopy. Pillaring was successful: the layers propped open and the basal distances increased significantly. For hydrotalcite this increase was always significantly larger than for montmorillonite. This fact indicated that the spatial arrangement of the amino acid moieties is widely different. A model for this arrangement is given.

Fudala, .; P嫮ink, I.; Kiricsi, I.

1999-05-01

247

Induction of amino acid transporters expression by endurance exercise in rat skeletal muscle  

SciTech Connect

Highlights: Regulation of amino acid transporter expression in working muscle remains unclear. Expression of amino acid transporters for leucine were induced by a bout of exercise. Requirement of leucine in muscle cells might regulate expression of its transporters. This information is beneficial for understanding the muscle remodeling by exercise. -- Abstract: We here investigated whether an acute bout of endurance exercise would induce the expression of amino acid transporters that regulate leucine transport across plasma and lysosomal membranes in rat skeletal muscle. Rats ran on a motor-driven treadmill at a speed of 28 m/min for 90 min. Immediately after the exercise, we observed that expression of mRNAs encoding L-type amino acid transporter 1 (LAT1) and CD98 was induced in the gastrocnemius, soleus, and extensor digitorum longus (EDL) muscles. Sodium-coupled neutral amino acid transporter 2 (SNAT2) mRNA was also induced by the exercise in those three muscles. Expression of proton-assisted amino acid transporter 1 (PAT1) mRNA was slightly but not significantly induced by a single bout of exercise in soleus and EDL muscles. Exercise-induced mRNA expression of these amino acid transporters appeared to be attenuated by repeated bouts of the exercise. These results suggested that the expression of amino acid transporters for leucine may be induced in response to an increase in the requirement for this amino acid in the cells of working skeletal muscles.

Murakami, Taro, E-mail: tamuraka@sgk.ac.jp; Yoshinaga, Mariko

2013-10-04

248

Extraterrestrial amino acids in the Almahata Sitta meteorite  

NASA Astrophysics Data System (ADS)

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

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

2010-10-01

249

Amino Acid Formation on Saturn's Inner Satellites  

NASA Astrophysics Data System (ADS)

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

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

2002-09-01

250

Formation of Amino Acid Thioesters for Prebiotic Peptide Synthesis: Catalysis By Amino Acid Products  

NASA Technical Reports Server (NTRS)

The origin of life can be described as a series of events in which a prebiotic chemical process came increasingly under the control of its catalytic products. In our search for this prebiotic process that yielded catalytic takeover products (such as polypeptides), we have been investigating a reaction system that generates peptide-forming amino acid thioesters from formaldehyde, glycolaldehyde, and ammonia in the presence of thiols. As shown below, this model process begins by aldol condensation of formaldehyde and glycolaldehyde to give trioses and releases. These sugars then undergo beta-dehydration yielding their respective alpha-ketoaldehydes. Addition of ammonia to the alpha-ketoaldehydes yields imines which can either: (a) rearrange in the presence of thesis to give amino acid thioesters or (be react with another molecule of aldehyde to give imidazoles. This 'one-pot' reaction system operates under mild aqueous conditions, and like modem amino acid biosynthesis, uses sugar intermediates which are converted to products by energy-yielding redox reactions. Recently, we discovered that amino acids, such as the alanine reaction product, catalyze the first and second steps of the process. In the presence of ammonia the process also generates other synthetically useful products, like the important biochemical -- pyruvic acid.

Weber, Arthur L.; DeVincenzi, Donald L. (Technical Monitor)

1999-01-01

251

Indicator assay for amino acid decarboxylases.  

PubMed

Indicator assays have been devised for glutamate decarboxylase and arginine decarboxylase as models for a general procedure for amino acid decarboxylases. Since the decarboxylation results in the absorption of a proton in the pH range of maximum enzymatic activity, the change in absorbance of an acid-base indicator can be used to follow the progress of the reaction. For glutamate decarboxylase, the substrate was used as the buffer, and 1-1'-diethyl-2-2'-cyanine iodide was used as the indicator. For arginine decarboxylase, acetate was used as the buffer, and bromcresol green was used as the indicator. The change in absorption with extent of reaction is linear if the indicator pK is equal to the buffer pK. PMID:2817382

Rosenberg, R M; Herreid, R M; Piazza, G J; O'Leary, M H

1989-08-15

252

Amino acid analysis for meat protein evaluation.  

PubMed

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

Ashworth, R B

1987-01-01

253

The Component Combined Amino Acids of Some Marine Phytoplankton Species  

Microsoft Academic Search

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

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

1967-01-01

254

Prebiotic Synthesis of Hydrophobic and Protein Amino Acids  

PubMed Central

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

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

1972-01-01

255

Novel class of amino acid antagonists at non-N-methyl-D-aspartic acid excitatory amino acid receptors. Synthesis, in vitro and in vivo pharmacology, and neuroprotection  

Microsoft Academic Search

The isoxazole amino acid 2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl) propionic acid (AMPA) (1), which is a highly selective agonist at the AMPA subtype of excitatory amino acid (EAA) receptors, has been used as a lead for the development of two novel EAA receptor antagonists. One of the compounds, 2-amino-3-(3-(carboxymethoxy)-5-methylisoxazol-4-yl)propionic acid (AMOA, 7), was synthesized via O-alkylation by ethyl chloroacetate of the amino acid protected

Povl Krogsgaard-Larsen; John W. Ferkany; Elsebet O. Nielsen; Ulf Madsen; Bjarke Ebert; Joergen S. Johansen; Nils H. Diemer; Torben Bruhn; David T. Beattie; David R. Curtis

1991-01-01

256

A reexamination of amino acids in lunar soil  

NASA Technical Reports Server (NTRS)

Amino acids in lunar soils provide an important indicator of the level of prebiotic organic compounds on the moon. The results provide insight into the chemistry of amino acid precursors, and furthermore, given the flux of carbonaceous material to the moon, we can evaluate the survival of organics upon impact. The amino acid contents of both hydrolyzed and unhydrolyzed hot-water extracts of Apollo 17 lunar soil were determined using ophthaldialdehyde/N-acetyl cysteine (OPA/NAC) derivatization followed by HPLC analysis. Previous studies of lunar amino acids were inconclusive, as the technique used (derivatization with ninhydrin followed by HPLC analysis) was unable to discriminate between cosmogenic amino acids and terrestrial contaminants. Cosmogenic amino acids are racemic, and many of the amino acids found in carbonaceous meteorites such as Murchison, i.e., alpha-amino-i-butyric acid (aib), are extremely rare on Earth. The ninhydrin method does not distinguish amino acid enantiomers, nor does it detect alpha-alkyl amino acids such as aib, whereas the OPA/NAC technique does both.

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

1993-01-01

257

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

258

Amino acid adsorption by clay minerals in distilled water  

NASA Astrophysics Data System (ADS)

The adsorption of 15 protein amino acids from dilute (~ 10 ?M) distilled water solutions onto organic-free kaolinite and montmorillonite clay minerals (1 wt% suspensions) was determined at room temperature over a 48 hour period. The systems came to steady state within 2 hours. Basic (positively charged) amino acids were strongly adsorbed (40-80% removal) by both clay minerals. Neutral (uncharged) amino acids were taken up appreciably (10-15%) by montmorillonite, but little if any (<5%) by kaolinite. Acidic (negatively charged) amino acids were adsorbed (20-35%) only by kaolinite. These adsorption patterns appear to be related in part to electrostatic interactions between the clay mineral surfaces and the different amino acid types. The measured extents and selectivities of adsorption onto these clay minerals are sufficiently great to potentially affect the distributions and reactions of free amino acids in natural environments.

Hedges, John I.; Hare, P. E.

1987-02-01

259

Amino acid distributions around O-linked glycosylation sites.  

PubMed Central

To study the sequence requirements for addition of O-linked N-acetylgalactosamine to proteins, amino acid distributions around 174 O-glycosylation sites were compared with distributions around non-glycosylated sites. In comparison with non-glycosylated serine and threonine residues, the most prominent feature in the vicinity of O-glycosylated sites is a significantly increased frequency of proline residues, especially at positions -1 and +3 relative to the glycosylated residues. Alanine, serine and threonine are also significantly increased. The high serine and threonine content of O-glycosylated regions is due to the presence of clusters of several closely spaced glycosylated hydroxy amino acids in many O-glycosylated proteins. Such clusters can be predicted from the primary sequence in some cases, but there is no apparent possibility of predicting isolated O-glycosylation sites from primary sequence data.

Wilson, I B; Gavel, Y; von Heijne, G

1991-01-01

260

Prebiotic Synthesis of Hydrophobic and Protein Amino Acids  

Microsoft Academic Search

The formation of amino acids by the action of electric discharges on a mixture of methane, nitrogen, and water with traces of ammonia was studied in detail. The presence of glycine, alanine, alpha -amino-n-butyric acid, alpha -aminoisobutyric acid, valine, norvaline, isovaline, leucine, isoleucine, alloisoleucine, norleucine, proline, aspartic acid, glutamic acid, serine, threonine, allothreonine, alpha -hydroxy-gamma -aminobutyric acid, and alpha ,gamma

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

1972-01-01

261

Engineered disulfide-forming amino acid substitutions interfere with a conformational change in the mismatch recognition complex Msh2-Msh6 required for mismatch repair.  

PubMed

ATP binding causes the mispair-bound Msh2-Msh6 mismatch recognition complex to slide along the DNA away from the mismatch, and ATP is required for the mispair-dependent interaction between Msh2-Msh6 and Mlh1-Pms1. It has been inferred from these observations that ATP induces conformational changes in Msh2-Msh6; however, the nature of these conformational changes and their requirement in mismatch repair are poorly understood. Here we show that ATP induces a conformational change within the C-terminal region of Msh6 that protects the trypsin cleavage site after Msh6 residue Arg(1124). An engineered disulfide bond within this region prevented the ATP-driven conformational change and resulted in an Msh2-Msh6 complex that bound mispaired bases but could not form sliding clamps or bind Mlh1-Pms1. The engineered disulfide bond also reduced mismatch repair efficiency in vivo, indicating that this ATP-driven conformational change plays a role in mismatch repair. PMID:23045530

Hargreaves, Victoria V; Putnam, Christopher D; Kolodner, Richard D

2012-11-30

262

Engineered Disulfide-forming Amino Acid Substitutions Interfere with a Conformational Change in the Mismatch Recognition Complex Msh2-Msh6 Required for Mismatch Repair*  

PubMed Central

ATP binding causes the mispair-bound Msh2-Msh6 mismatch recognition complex to slide along the DNA away from the mismatch, and ATP is required for the mispair-dependent interaction between Msh2-Msh6 and Mlh1-Pms1. It has been inferred from these observations that ATP induces conformational changes in Msh2-Msh6; however, the nature of these conformational changes and their requirement in mismatch repair are poorly understood. Here we show that ATP induces a conformational change within the C-terminal region of Msh6 that protects the trypsin cleavage site after Msh6 residue Arg1124. An engineered disulfide bond within this region prevented the ATP-driven conformational change and resulted in an Msh2-Msh6 complex that bound mispaired bases but could not form sliding clamps or bind Mlh1-Pms1. The engineered disulfide bond also reduced mismatch repair efficiency in vivo, indicating that this ATP-driven conformational change plays a role in mismatch repair.

Hargreaves, Victoria V.; Putnam, Christopher D.; Kolodner, Richard D.

2012-01-01

263

Catalytic hydrogenation of amino acids to amino alcohols with complete retention of configuration.  

PubMed

Rh-MoOx/SiO2 is an effective heterogeneous catalyst for selective hydrogenation of amino acids to amino alcohols in a water solvent. MoOx modification of Rh drastically enhanced the activity and improved the selectivity and ee. Various amino alcohols were obtained in high yields (90-94%) with complete retention of configuration. PMID:24824793

Tamura, Masazumi; Tamura, Riku; Takeda, Yasuyuki; Nakagawa, Yoshinao; Tomishige, Keiichi

2014-05-27

264

Unprecedented concentrations of indigenous amino acids in primitive CR meteorites  

NASA Astrophysics Data System (ADS)

CR meteorites are among the most primitive meteorites. We have performed pioneering work determining the compositional characteristics of amino acids in this type of carbonaceous chondrites. 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. We have analyzed the amino acid content of the Antarctic CRs EET92042, GRA95229 and GRO95577 using high performance liquid chromatography with UV fluorescence detection (HPLC-FD) and gas chromatography-mass spectrometry (GC-MS). Additionally, compound-specific carbon isotopic measurements for most of the individual amino acids from the EET92042 and GRA95229 meteorites were achieved by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). Our data show that EET92042 and GRA95229 are the most amino acid-rich chondrites ever analyzed, with total amino acid concentrations of 180 and 249 parts-per-million (ppm), respectively. GRO95577, however, is depleted in amino acids (<1 ppm). The most abundant amino acids present in the EET92042 and GRA95229 meteorites are the ?-amino acids glycine, isovaline, ?-aminoisobutyric acid (?-AIB), and alanine, with ? 13 C values ranging from +31.6% to +50.5%. The highly enriched carbon isotope results together with racemic enantiomeric ratios determined for most amino acids indicate that primitive organic matter was preserved in these meteorites. In addition, the relative abundances of ?-AIB and ?-alanine amongst Antarctic CR meteorites appear to correspond to the degree of aqueous alteration on their respective parent body. Investigating the abundances and isotopic composition of amino acids in primitive chondrites helps to understand the role of meteorites as a source of extraterrestrial prebiotic organic compounds to the early Earth.

Ehrenfreund, Pascale; Martins, Zita; Alexander, Conel; Orzechowska, Grazyna; Fogel, Marylin

265

Plasma amino acid quantitation using gas chromatography chemical ionization mass spectrometry and 13C amino acids as internal standards.  

PubMed

A specific and sensitive method for the quantitation of 16 alpha amino acids has been developed. The technique employed uses methane chemical ionization gas chromatography mass spectrometry of the carboxy-n-butyl, N-trifluoroacetyl amino acid derivatives. A commercial 13C amino acid mixture provided individual internal standards for 14 alpha amino acids. A computer controlled quadrupole mass spectrometer was used for selected ion monitoring of those ions characteristic of each N-trifluoroacetyl amino acid/13C amino acid pair. A BASIC computer program located peak maxima and background intensities in each selected ion recording. Standard curves for each amino acid/13C amino acid pair were utilized by the program to calculate the plasma concentration of each detected amino acid. The total instrumental analysis occupied 30 min with sample preparation and derivatization accounting for an additional 2 h. Based on the detection of known amounts of standard amino acids the method will quantitate at the 1-5 nanogram level of detection. PMID:749957

Kingston, E E; Duffield, A M

1978-11-01

266

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...

267

Diagnosis in bile acid-CoA: Amino acid N-acyltransferase deficiency  

PubMed Central

Cholate-CoA ligase (CCL) and bile acid-CoA: amino acid N-acyltransferase (BAAT) sequentially mediate bile-acid amidation. Defects can cause intrahepatic cholestasis. Distinction has required gene sequencing. We assessed potential clinical utility of immunostaining of liver for CCL and BAAT. Using commercially available antibodies against BAAT and CCL, we immunostained liver from an infant with jaundice, deficiency of amidated bile acids, and transcription-terminating mutation in BAAT. CCL was normally expressed. BAAT expression was not detected. Immunostaining may facilitate diagnosis in bile-acid amidation defects.

Hadzic, Nedim; Bull, Laura N; Clayton, Peter T; Knisely, AS

2012-01-01

268

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

269

[Amino acid sequence of anionic protease inhibitors from buckwheat seeds].  

PubMed

Complete amino acid sequence of IT1 protease inhibitor and partial amino acid sequences of IT2 and IT4 protease inhibitors from buckwheat Fagopyrum esculentum Moench seeds were determined by automatic Edman degradation and mass spectrometry. IT1 inhibitor comprises 69 amino acid residues and its molecular mass is 7743.8 D. N-terminal 48 amino acid residues of IT2 inhibitor are identical to similar sequence of IT1 inhibitor. The sequence of 10 amino acid residues of IT4 inhibitor is completely identical to a part of the sequence of IT1 inhibitor C-terminally adjacent to its active site. Analysis of amino acid sequences of IT1, IT2 and IT4 inhibitors suggests that the proteins are the members of the potato proteinase inhibitor 1 family and include Arg-Asp residues in their active site. PMID:9011225

Belozerski?, M A; Dunaevski?, Ia E; Musaliamov, A Kh; Egorov, Ts A

1996-10-01

270

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

271

Screening for defects of branched-chain amino acid metabolism  

Microsoft Academic Search

Screening for defects of branched-chain amino acid metabolism is a sequential process involving clinical evaluation of the patient, plasma carnitine determination, urinary organic acid analysis, and enzyme studies in cultured or isolated peripheral cells. This report will summarize clinical and metabolite features and enzymological methods available for the diagnosis of the more common defects of branchedchain amino acid metabolism, including

K. Michael Gibson; Carol F. Lee; Georg F. Hoffmann

1994-01-01

272

Amino acids of the Murchison meteorite. II - Five carbon acyclic primary beta-, gamma-, and delta-amino alkanoic acids  

NASA Technical Reports Server (NTRS)

The five-carbon acyclic primary beta, gamma, and delta amino alkanoic acids of the Murchison meteorite are studied using gas chromatography-mass spectrometry and ion exchange chromatography. The chromatograms reveal that alpha is the most abundant monoamino alkanoic acid followed by gamma and beta, and an exponential increase in the amount of amino acid is observed as the carbon number increases in the homologous series. The influence of frictional heating, spontaneous thermal decomposition, and radiation of the synthesis of amino acids is examined. The data obtained support an amino acid synthesis process involving random combination of single-carbon precursors.

Cronin, J. R.; Pizzarello, S.; Yuen, G. U.

1985-01-01

273

Amino acid transport in the renal proximal tubule  

Microsoft Academic Search

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

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

2000-01-01

274

Peptidology: short amino acid modules in cell biology and immunology  

Microsoft Academic Search

Summary.Short amino acid motifs, either linear sequences or discontinuous amino acid groupings, can interact with specific protein\\u000a domains, so exerting a central role in cell adhesion, signal transduction, hormone activity, regulation of transcript expression,\\u000a enzyme activity, and antigen-antibody interaction. Here, we analyze the literature for such critical short amino acid motifs\\u000a to determine the minimal peptide length involved in biologically

G. Lucchese; A. Stufano; B. Trost; A. Kusalik; D. Kanduc

2007-01-01

275

GLC of amino acids - A survey of contamination.  

NASA Technical Reports Server (NTRS)

Analyses of biological substances and geochemical samples, of both terrestrial and extraterrestrial origin, are reported for amino acids at the 1-10 nanogram per gram level achieved by gas-liquid and ion-exchange chromatographic methods. These studies have shown that nanogram quantities of amino acids, present in water extracts of geochemical samples or in other samples of low amino acid concentration, can be successfully determined only if the researcher is well aware of the possible sources of contamination.

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

1972-01-01

276

Synthesis of alpha-amino acids  

DOEpatents

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

Davis, J.W. Jr.

1983-01-25

277

Metabolic efficiency and amino acid composition in the proteomes of Escherichia coli and Bacillus subtilis  

PubMed Central

Biosynthesis of an Escherichia coli cell, with organic compounds as sources of energy and carbon, requires approximately 20 to 60 billion high-energy phosphate bonds [Stouthamer, A. H. (1973) Antonie van Leeuwenhoek 39, 545565]. A substantial fraction of this energy budget is devoted to biosynthesis of amino acids, the building blocks of proteins. The fueling reactions of central metabolism provide precursor metabolites for synthesis of the 20 amino acids incorporated into proteins. Thus, synthesis of an amino acid entails a dual cost: energy is lost by diverting chemical intermediates from fueling reactions and additional energy is required to convert precursor metabolites to amino acids. Among amino acids, costs of synthesis vary from 12 to 74 high-energy phosphate bonds per molecule. The energetic advantage to encoding a less costly amino acid in a highly expressed gene can be greater than 0.025% of the total energy budget. Here, we provide evidence that amino acid composition in the proteomes of E. coli and Bacillus subtilis reflects the action of natural selection to enhance metabolic efficiency. We employ synonymous codon usage bias as a measure of translation rates and show increases in the abundance of less energetically costly amino acids in highly expressed proteins.

Akashi, Hiroshi; Gojobori, Takashi

2002-01-01

278

Prebiotic Amino Acid Thioester Synthesis: Thiol-Dependent Amino Acid Synthesis from Formose substrates (Formaldehyde and Glycolaldehyde) and Ammonia  

NASA Technical Reports Server (NTRS)

Formaldehyde and glycolaldehyde (substrates of the formose autocatalytic cycle) were shown to react with ammonia yielding alanine and homoserine under mild aqueous conditions in the presence of thiol catalysts. Since similar reactions carried out without ammonia yielded alpha-hydroxy acid thioesters, the thiol-dependent synthesis of alanine and homoserine is presumed to occur via amino acid thioesters-intermediates capable of forming peptides. A pH 5.2 solution of 20 mM formaldehyde, 20 mM glycolaldehyde, 20 mM ammonium chloride, 23 mM 3-mercaptopropionic acid, and 23 mM acetic acid that reacted for 35 days at 40 C yielded (based on initial formaldehyde) 1.8% alanine and 0.08% homoserine. In the absence of thiol catalyst, the synthesis of alanine and homoserine was negligible. Alanine synthesis required both formaldehyde and glycolaldehyde, but homoserine synthesis required only glycolaldehyde. At 25 days the efficiency of alanine synthesis calculated from the ratio of alanine synthesized to formaldehyde reacted was 2.1%, and the yield (based on initial formaldehyde) of triose and tetrose intermediates involved in alanine and homoserine synthesis was 0.3 and 2.1%, respectively. Alanine synthesis was also seen in similar reactions containing only 10 mM each of aldehyde substrates, ammonia, and thiol. The prebiotic significance of these reactions that use the formose reaction to generate sugar intermediates that are converted to reactive amino acid thioesters is discussed.

Weber, Arthur L.

1998-01-01

279

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 proteinprotein 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.

Nijveen, Harm

2014-01-01

280

Which Amino Acids Should Be Used in Prebiotic Chemistry Studies?  

NASA Astrophysics Data System (ADS)

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

Zaia, Dimas A. M.; Zaia, C嫳sia Tha鮢 B. V.; de Santana, Henrique

2008-12-01

281

Analysis of Amino Acid Isotopomers using FT-ICR MS  

SciTech Connect

Fluxes through known metabolic pathways and the presence ofnovel metabolic reactions are often determined by feedingisotopically-labeled substrate to an organism and then determining theisotopomer distribution in amino acids in proteins. However, commonlyused techniques to measure the isotopomer distributions requirederivatization prior to analysis (gas chromatography-mass spectrometry(GC-MS)) or large sample sizes (nuclear magnetic resonance (NMR)spectroscopy). Here, we demonstrate the use of Fourier Transform-IonCyclotron Resonance Mass Spectrometry (FT-ICR MS) with direct infusionvia electrospray ionization to rapidly measure the amino acid isotopomerdistribution in a biomass hydrolysate of the soil bacterium Desulfovibriovulgaris Hildenborough. By applying high front-end resolution for theprecursor ion selection followed by sustained off-resonance irradiation -collision-induced dissociation (SORI-CID), it was possible to determineexactly and unambiguously the specific locations of the labeled atoms inthe amino acids, which usually requires a combination of 2-D 13C NMRspectroscopy and GC-MS. This method should be generally applicable toallbiomass samples and will allow more accurate determination of metabolicfluxes with less work and less sample.

Pingitore, Francesco; Tang, Yinjie; Kruppa, Gary H.; Keasling,Jay D.

2006-10-08

282

Predicting a protein's melting temperature from its amino acid sequence.  

PubMed

Melting temperature is an important characteristic feature of a protein and is used for various purposes such as in drug development. Currently protein melting temperature is determined by laboratory methods such as Differential Scanning Calorimetry, Circular Dichroism, Fourier transform infrared spectroscopy and several other methods. These methods are laborious and costly. Therefore, we propose a novel bioinformatics based method for predicting protein melting temperature from amino acid sequence of a protein. This is not only a challenging task but has been previously unexplored. For this study, melting temperature of 230 proteins from a range of organisms was collected along with their sequence information from the published literature. The melting temperature of these proteins represents a very large spectrum and varies between 25蚓 and 113蚓. The protein sequences are then used to derive two sets of sequence-driven features, namely amino acid composition (AAC) and pseudo-amino acid composition (PseudoAAC) to characterise the proteins. In order to predict the melting temperature, two different computational intelligence methods, namely artificial neural networks (ANN) and adaptive network-fuzzy inference system (ANFIS) were utilized. Amongst over 100 different models generated, the ANN produced the best model with the least error (0.01087 for the AAC and 0.01086 for the pseudoAAC). As both feature sets yielded quite similar error and computation of pseudoAAC is costly when compared to that of AAC, traditional AAC seems to be an effective feature set for predicting melting temperature. The results obtained in this study are very promising and, for the first time, shows that the melting temperature of a protein can be predicted from its amino acid sequence only. Therefore, costly lab-based experiments may not be required to measure the melting temperature and the bioinformatics models can help speed up laboratory processes such as in drug development. PMID:21095941

Gorania, Malde; Seker, Huseyin; Haris, Parvez I

2010-01-01

283

The effect of hydrolysis time on amino acid analysis.  

PubMed

Determining the amino acid content of a protein involves the hydrolysis of that protein, usually in acid, until the protein-bound amino acids are released and made available for detection. Both the variability in the ease of peptide bond cleavage and differences in the acid stability of certain amino acids can significantly affect determination of a protein's amino acid content. By using multiple hydrolysis intervals, a greater degree of accuracy can be obtained in amino acid analysis. Correction factors derived by linear extrapolation of serial hydrolysis data are currently used. Compartmental modeling of the simultaneous hydrolysis (yield) and degradation (decay) of amino acids by nonlinear multiple regression of serial hydrolysis data has also been validated and applied to determine the amino acid composition of various biological samples, including egg-white lysozyme, human milk protein, and hair. Implicit in the routine application of serial hydrolysis in amino acid analysis, however, is an understanding that correction factors, derived either linearly or through the more accurate nonlinear multiple regression approach, need to be determined for individual proteins rather than be applied uniformly across all protein types. PMID:16001867

Darragh, Alison J; Moughan, Paul J

2005-01-01

284

Amino Acid Toxicities of Escherichia coli That Are Prevented by Leucyl-tRNA Synthetase Amino Acid Editing  

Microsoft Academic Search

In the first step of protein synthesis, an aminoacyl-tRNA synthetase (aaRSs) is responsible for linking a single standard amino acid to its correct set of tRNA isoacceptors (11, 20). About half of the family of 20 aaRSs are challenged to distin- guish among closely related amino acids and have evolved amino-acid-editing mechanisms to clear their mistakes (10). These editing mechanisms

Vrajesh A. Karkhanis; Anjali P. Mascarenhas; Susan A. Martinis

2007-01-01

285

Production of ?-keto acids Part I. Immobilized cells ofTrigonopsis variabilis containing D-amino acid oxidase.  

PubMed

Whole cells ofTrigonopsis variabilis were immobilized by entrapment in Ca(2+)-alginate and used for the production of ?-keto acids from the corresponding D-amino acids. The D-amino acid oxidase within the immobilized cells has a broad substrate specificity. Hydrogen peroxide formed in the enzymatic reaction was efficiently hydrolyzed by manganese oxide co-immobilized with the cells. The amino acid oxidase activity was assayed with a new method based on reversed-phase HPLC. Oxygen requirements, bead size, concentration of cells in the beads, flow rate, and other factors were investigated in a " trickle-bed " reactor. PMID:24233977

Brodelius, P; Nilsson, K; Mosbach, K

1981-12-01

286

The biosynthetic gene cluster for coronamic acid, an ethylcyclopropyl amino acid, contains genes homologous to amino acid-activating enzymes and thioesterases.  

PubMed Central

Coronamic acid (CMA), an ethylcyclopropyl amino acid derived from isoleucine, functions as an intermediate in the biosynthesis of coronatine, a chlorosis-inducing phytotoxin produced by Pseudomonas syringae pv. glycinea PG4180. The DNA required for CMA biosynthesis (6.9 kb) was sequenced, revealing three distinct open reading frames (ORFs) which share a common orientation for transcription. The deduced amino acid sequence of a 2.7-kb ORF designated cmaA contained six core sequences and two conserved motifs which are present in a variety of amino acid-activating enzymes, including nonribosomal peptide synthetases. Furthermore, CmaA contained a spatial arrangement of histidine, aspartate, and arginine residues which are conserved in the ferrous active site of some nonheme iron(II) enzymes which catalyze oxidative cyclizations. The deduced amino acid sequence of a 1.2-kb ORF designated cmaT was related to thioesterases of both procaryotic and eucaryotic origins. These data suggest that CMA assembly is similar to the thiotemplate mechanism of nonribosomal peptide synthesis. No significant similarities between a 0.9-kb ORF designated cmaU and other database entries were found. The start sites of two transcripts required for CMA biosynthesis were identified in the present study. pRG960sd, a vector containing a promoterless glucuronidase gene, was used to localize and study the promoter regions upstream of the two transcripts. Data obtained in the present study indicate that CMA biosynthesis is regulated at the transcriptional level by temperature. Images

Ullrich, M; Bender, C L

1994-01-01

287

Patterns of Amino Acid Metabolism by Proliferating Human Mesenchymal Stem Cells  

PubMed Central

The nutritional requirements of stem cells have not been determined; in particular, the amino acid metabolism of stem cells is largely unknown. In this study, we investigated the amino acid metabolism of human mesenchymal stem cells (hMSCs), with focus on two questions: Which amino acids are consumed and/or secreted by hMSCs and at what rates? To answer these questions, hMSCs were cultured on tissue culture plastic and in a bioreactor, and their amino acid profile was analyzed. The results showed that the kinetics of hMSCs growth and amino acid metabolism were significantly higher for hMSCs in tissue culture plastic than in the bioreactor. Despite differences in culture conditions, 8 essential and 6 nonessential amino acids were consumed by hMSCs in both tissue culture plastic and bioreactor cultures. Glutamine was the most consumed amino acid with significantly higher rates than for any other amino acid. The metabolism of nonessential amino acids by hMSCs deviated significantly from that of other cell lines. The secretion of alanine, glycine, glutamate, and ornithine by hMSCs showed that there is a strong overflow metabolism that can be due to the high concentrations of amino acids provided in the medium. In addition, the data showed that there is a metabolic pattern for proliferating hMSCs, which can contribute to the design of medium without animal serum for stem cells. Further, this study shows how to implement amino acid rates and metabolic principles in three-dimensional stem cell biology.

Schop, Deborah; Spitters, Tim W.G.M.; van Dijkhuizen-Radersma, Riemke; Bracke, Madelon; de Bruijn, Joost D.; Martens, Dirk; Karperien, Marcel; van Boxtel, Anton; van Blitterswijk, Clemens A.

2012-01-01

288

Utilization of Acidic ?-Amino Acids as Acyl Donors: An Effective Stereo-Controllable Synthesis of Aryl-Keto ?-Amino Acids and Their Derivatives.  

PubMed

Aryl-keto-containing ?-amino acids are of great importance in organic chemistry and biochemistry. They are valuable intermediates for the construction of hydroxyl ?-amino acids, nonproteinogenic ?-amino acids, as well as other biofunctional components. Friedel-Crafts acylation is an effective method to prepare aryl-keto derivatives. In this review, we summarize the preparation of aryl-keto containing ?-amino acids by Friedel-Crafts acylation using acidic ?-amino acids as acyl-donors and Lewis acids or Br霵sted acids as catalysts. PMID:24840903

Wang, Lei; Murai, Yuta; Yoshida, Takuma; Okamoto, Masashi; Tachrim, Zetryana Puteri; Hashidoko, Yasuyuki; Hashimoto, Makoto

2014-01-01

289

Supervised learning method for the prediction of subcellular localization of proteins using amino acid and amino acid pair composition  

PubMed Central

Background Occurrence of protein in the cell is an important step in understanding its function. It is highly desirable to predict a protein's subcellular locations automatically from its sequence. Most studied methods for prediction of subcellular localization of proteins are signal peptides, the location by sequence homology, and the correlation between the total amino acid compositions of proteins. Taking amino-acid composition and amino acid pair composition into consideration helps improving the prediction accuracy. Results We constructed a dataset of protein sequences from SWISS-PROT database and segmented them into 12 classes based on their subcellular locations. SVM modules were trained to predict the subcellular location based on amino acid composition and amino acid pair composition. Results were calculated after 10-fold cross validation. Radial Basis Function (RBF) outperformed polynomial and linear kernel functions. Total prediction accuracy reached to 71.8% for amino acid composition and 77.0% for amino acid pair composition. In order to observe the impact of number of subcellular locations we constructed two more datasets of nine and five subcellular locations. Total accuracy was further improved to 79.9% and 85.66%. Conclusions A new SVM based approach is presented based on amino acid and amino acid pair composition. Result shows that data simulation and taking more protein features into consideration improves the accuracy to a great extent. It was also noticed that the data set needs to be crafted to take account of the distribution of data in all the classes.

Habib, Tanwir; Zhang, Chaoyang; Yang, Jack Y; Yang, Mary Qu; Deng, Youping

2008-01-01

290

Amino acids regulate transgene expression in MDCK cells.  

PubMed

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, J顤n Oliver; Arps, Lisa; Ruckstuhl, Lisa; Camargo, Simone M R; Verrey, Fran蔞is

2014-01-01

291

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.

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

2014-01-01

292

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

293

Gas-phase Acidities of Aspartic Acid, Glutamic Acid, and their Amino Acid Amides.  

SciTech Connect

Gas-phase acidities (GA or ?Gacid) for the two most acidic common amino acids, aspartic acid and glutamic acid, have been determined for the first time. Because of the amide linkages importance in peptides and as an aid in studying side chain versus main chain deprotonation, aspartic acid amide and glutamic acid amide were also studied. Experimental GA values were measured by proton transfer reactions in an electrospray ionization/Fourier transform ion cyclotron resonance mass spectrometer. Calculated GAs were obtained by density functional and molecular orbital theory approaches. The best agreement with experiment was found at the G3MP2 level; the MP2/CBS and B3LYP/aug-cc-pVDZ results are 34 kcal/mol more acidic than the G3MP2 results. Experiment shows that aspartic acid is more acidic than glutamic acid by ca. 3 kcal/mol whereas the G3MP2 results show a smaller acidity difference of 0.2 kcal/mol. Similarly, aspartic acid amide is experimentally observed to be ca. 2 kcal/mol more acidic than glutamic acid amide whereas the G3MP2 results show a correspondingly smaller energy difference of 0.7 kcal/mol. The computational results clearly show that the anions are all ring-like structures with strong hydrogen bonds between the OH or NH2 groups and the CO2? group from which the proton is removed. The two amino acids are main-chain deprotonated. In addition, use of the COSMO model for the prediction of the free energy differences in aqueous solution gave values in excellent agreement with the most recent experimental values for pKa. Glutamic acid is predicted to be more acidic than aspartic acid in aqueous solution due to differential solvation effects.

Li, Zhong; Matus, Myrna H.; Velazquez, Hector A.; Dixon, David A.; Cassady, Carolyn J.

2007-02-14

294

Gas-phase acidities of aspartic acid, glutamic acid, and their amino acid amides  

NASA Astrophysics Data System (ADS)

Gas-phase acidities (GA or [Delta]Gacid) for the two most acidic common amino acids, aspartic acid and glutamic acid, have been determined for the first time. Because of the amide linkage's importance in peptides and as an aid in studying side chain versus main chain deprotonation, aspartic acid amide and glutamic acid amide were also studied. Experimental GA values were measured by proton transfer reactions in an electrospray ionization/Fourier transform ion cyclotron resonance mass spectrometer. Calculated GAs were obtained by density functional and molecular orbital theory approaches. The best agreement with experiment was found at the G3MP2 level; the MP2/CBS and B3LYP/aug-cc-pVDZ results are 3-4 kcal/mol more acidic than the G3MP2 results. Experiment shows that aspartic acid is more acidic than glutamic acid by ca. 3 kcal/mol whereas the G3MP2 results show a smaller acidity difference of 0.2 kcal/mol. Similarly, aspartic acid amide is experimentally observed to be ca. 2 kcal/mol more acidic than glutamic acid amide whereas the G3MP2 results show a correspondingly smaller energy difference of 0.7 kcal/mol. The computational results clearly show that the anions are all ring-like structures with strong hydrogen bonds between the OH or NH2 groups and the CO2- group from which the proton is removed. The two amino acids are main-chain deprotonated. In addition, use of the COSMO model for the prediction of the free energy differences in aqueous solution gave values in excellent agreement with the most recent experimental values for pKa. Glutamic acid is predicted to be more acidic than aspartic acid in aqueous solution due to differential solvation effects.

Li, Zhong; Matus, Myrna H.; Velazquez, Hector Adam; Dixon, David A.; Cassady, Carolyn J.

2007-09-01

295

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)

2009-04-28

296

Molecular regulation of amino acid biosynthesis in plants  

Microsoft Academic Search

Our understanding of amino acid biosynthesis in plants has grown by leaps and bounds in the last decade. It appears that most of the amino acid biosynthesis takes place in the chloroplast. Recent demonstration of glutamine synthetase and DAHP synthase in the vascular tisuue has added a new dimension in the complexity of the nitrogen cycle in plants. Isolation of

B. K. Singh; B. F. Matthews

1994-01-01

297

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

298

Modeling amino acid substitution patterns in orthologous and paralogous genes  

Microsoft Academic Search

We study to what degree patterns of amino acid substitution vary between genes using two models of protein-coding gene evolution. The first divides the amino acids into groups, with one substitution rate for pairs of residues in the same group and a second for those in differing groups. Unlike previous applications of this model, the groups themselves are estimated from

Gavin C. Conant; Gnter P. Wagner; Peter F. Stadler

2007-01-01

299

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)

2011-12-06

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

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)

2012-02-14

302

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

303

Amino acid metabolism and the energetics of growth  

Microsoft Academic Search

The nonessential amino acids are involved in a large number of functions that are not directly associated with protein synthesis. Recent studies using a combination of transorgan balance and stable isotopic tracers have demonstrated that a substantial portion of the extra?splanchnic flux of glutamate, glutamine, glycine and cysteine derives from tissue synthesis. A key amino acid in this respect is

P. J. Reeds; D. G. Burrin; T. A. Davis; B. Stoll

1998-01-01

304

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.

305

Plasma Amino Acid Response to Graded Levels of Escape Protein  

Microsoft Academic Search

A trial was conducted to examine the potential of using plasma amino acid responses to graded levels of escape protein to determine limiting amino acids in cattle. Growing calves (n = 120; i BW = 220 f 21 kg) were fed a basal diet of corncobsorghum silage (61:39) and were individually supplemented with distillers' dried grains (DDG), heat-damaged DDG (H-DDG),

D. J. Gibb; T. J. Klopfenstein; R. A. Britton; A. J. Lewis

2010-01-01

306

Stability of free amino acid levels in stressed Abarenicola pacifica  

Microsoft Academic Search

JEFFRIES (1972), BAYNE et al. (1976), and ROESIJADI + ANDERSON (1979) have described a change in the composition of the free amino acid (FAA) pool of pelecypod molluscs under stress. This response consists of a significant decrease in the level of glycine, while the taurine level remains constant, leading to a decrease in the total free amino acid level and

J. M. Augenfeld; J. W. Anderson

1980-01-01

307

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

308

Amino Acids in Uremia. Short-Term Daily Peritoneal Dialysis.  

National Technical Information Service (NTIS)

The research has been directed toward the study: (1) of adverse effects among basic amino-acids in uremia, (2) of short daily peritoneal dialysis. Small amino acid loads have been administered orally to a group of normal and uremic subjects. Fasting plasm...

C. Giordano N. G. De Santo E. Esposito

1974-01-01

309

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 Schller; Jaap J. Beintema; Jaap Broos; Janneke Meulenberg

1985-01-01

310

Amino acids from ultraviolet irradiation of interstellar ice analogues  

Microsoft Academic Search

Amino acids are the essential molecular components of living organisms on Earth, but the proposed mechanisms for their spontaneous generation have been unable to account for their presence in Earth's early history. The delivery of extraterrestrial organic compounds has been proposed as an alternative to generation on Earth, and some amino acids have been found in several meteorites. Here we

G. M. Mu隳z Caro; U. J. Meierhenrich; W. A. Schutte; B. Barbier; A. Arcones Segovia; H. Rosenbauer; W. H.-P. Thiemann; A. Brack; J. M. Greenberg

2002-01-01

311

Net placental transfer of free amino acids against varying concentrations  

PubMed Central

1. The patterns of the free plasma amino acids in the pregnant guinea-pig and her foetuses, near term, are described. The concentration of each amino acid was higher in the foetal plasma than in the maternal. The foetal:maternal gradients (F:M) varied for each amino acid; the straight chain amino acids had the highest F:M ratios. 2. Net transfer of endogenous plasma amino acids, from the maternal circulation across the placental membrane, was studied. The foetus was removed and the foetal placenta perfused in situ via the umbilical arteries, with an artificial fluid containing varying concentrations of amino acids. 3. All the amino acids, both essential and non-essential, could be transferred from the maternal to the foetal circulation against the F:M gradients. With `closed circuit' perfusion, this transport increased the concentration of total amino N in the perfusate until it was twice that of the normal F:M gradient of 5. The concentrations of the individual amino acids was increased to 17-42 times those normally present in foetal plasma, and the final values reached were similar to the concentrations of free amino acid found in placental tissue. 4. The umbilical veinartery differences were small, with the placenta perfused `open circuit' in the steady state, using physiological flow rates and amino acid concentrations. The average net placental transfer of amino N found was 114 m-mole min-1. This is about 60% of the calculated net rate of accumulation of N by the 60 g guinea-pig foetus. 5. The influence of foetal placental perfusion concentration on transfer was small but significant. In the steady state, the transfer of amino N, and each individual amino acid, was found to be inversely proportional to the concentrations in the perfusate when the placenta was perfused `open circuit'. The slopes of the regression of transfer on concentration had an average value of 013 n-mole min-1 g-1 per ?mole. No significant difference in the slopes was found between the three amino acid transport groups. 6. Net transfer was independent of perfusate flow, within the physiological range, which suggests a secretory process across the membrane from maternal to foetal circulation.

Hill, Penny M. M.; Young, Maureen

1973-01-01

312

Amino acids and osmolarity in honeybee drone haemolymph.  

PubMed

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 amino acids were observed. This coincides with the age when drones reach sexual maturity and change their feeding behaviour. Levels of essential free amino acids were high during the first 3 days of life and thereafter decreased. Osmolarity was lowest at emergence (334 +/- 42 mOsm), increased until the age of 3 days (423 +/- 32 mOsm) and then stayed generally constant until the 16th day of life. Only 25-day-old drones had significantly higher osmolarity (532 +/- 38 mOsm). The overall change in osmolarity during a drone's lifetime was about 40%. PMID:10524277

Leonhard, B; Crailsheim, K

1999-01-01

313

Stardust, Supernovae and the Chirality of the Amino Acids  

SciTech Connect

A mechanism for creating enantiomerism in the amino acids, the building blocks of the proteins, that involves global selection of one chirality by interactions between the amino acids and neutrinos from core-collapse supernovae is described. The 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. 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 amino acids.

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

2011-03-09

314

Amino Acid Analyses of Acid Hydrolysates in Desert Varnish  

NASA Technical Reports Server (NTRS)

There has long been a debate as to whether rock varnish deposits are microbially mediated or are deposited by inorganic processes. Varnished rocks are found throughout the world primarily in arid and semi-arid regions. The varnish coats are typically up to 200 microns thick and are composed of clays and alternating layers enriched in manganese and iron oxides. The individual layers range in thickness from 1 micron to greater than 10 microns and may continue laterally for more than a 100 microns. Overlapping botryoidal structures are visible in thin section and scanning electron micrographs. The coatings also include small amounts of organic mater and detrital grains. Amino-acid hydrolysates offer a means of assessing the organic composition of rock varnish collected from the Sonoran Desert, near Phoenix, AZ. Chromatographic analyses of hydrolysates from powdered samples of rock varnish suggest that the interior of rock varnish is relatively enriched in amino acids and specifically in d-alanine and glutamic acid. Peptidoglycan (murein) is the main structural component of gram-positive bacterial cell walls. The d-enantiomer of alanine and glutamic acid are specific to peptidoglycan and are consequently an indicator for the presence of bacteria. D-alanine is also found in teichoic acid which is only found in gram-positive bacteria. Several researchers have cultured bacteria from the surface of rock varnish and most have been gram-positive, suggesting that gram-positive bacteria are intimately associated with varnish coatings and may play a role in the formation of varnish coatings.

Perry, Randall S.; Staley, James T.; Dworkin, Jason P.; Engel, Mike

2001-01-01

315

Amino acid sensing in the gastrointestinal tract.  

PubMed

Rapid progress in gastroenterology during the first part of the last century has shown that gastrointestinal (GI) function is regulated by neuroendocrine, paracrine and endocrine signals. However, recent advances in chemical sensing, especially in the last decade, have revealed that free L-amino acids (AA), among other nutrients, play a critical role in modifying exocrine and endocrine secretion, modulating protein digestion, metabolism and nutrient utilization, and supporting the integrity and defense of the GI mucosa. Many of the mechanisms by which AAs elicit these functions in the GI has been linked to the traditional concept of hormone release and nervous system activation. But most these effects are not direct. AAs appear to function by binding to a chemical communication system such as G protein-coupled receptors (GPCRs) that activate signaling pathways. These intracellular signals, although their molecular bases are not completely elucidated yet, are the ones responsible for the neuronal activity and release of hormones that in turn regulate GI functions. This review aims to describe the distribution of the known GPCRs from the class 3 superfamily that bind to different kinds of AA, especially from the oropharyngeal cavity to the stomach, what kind of taste qualities they elicit, such as umami, bitter or sweet, and their activity in the GI tract. PMID:22865248

San Gabriel, Ana; Uneyama, Hisayuki

2013-09-01

316

Wet, Carbonaceous Asteroids: Altering Minerals, Changing Amino Acids  

NASA Astrophysics Data System (ADS)

Many carbonaceous chondrites contain alteration products from water-rock interactions at low temperature and organic compounds. A fascinating fact known for decades is the presence in some of them of an assortment of organic compounds, including amino acids, sometimes called the building blocks of life. Murchison and other CM carbonaceous chondrites contain hundreds of amino acids. Early measurements indicated that the amino acids in carbonaceous chondrites had equal proportions of L- and D-structures, a situation called racemic. This was in sharp contrast to life on Earth, which heavily favors L- forms. However, beginning in 1997, John Cronin and Sandra Pizzarello (Arizona State University) found L- excesses in isovaline and several other amino acids in the Murchison carbonaceous chondrite. In 2009, Daniel Glavin and Jason Dworkin (Astrobiology Analytical Lab, Goddard Space Flight Center) reported the first independent confirmation of L-isovaline excesses in Murchison using a different analytical technique than employed by Cronin and Pizzarello. Inspired by this work, Daniel Glavin, Michael Callahan, Jason Dworkin, and Jamie Elsila (Astrobiology Analytical Lab, Goddard Space Flight Center), have done an extensive study of the abundance and symmetry of amino acids in carbonaceous chondrites that experienced a range of alteration by water in their parent asteroids. The results show that amino acids are more abundant in the less altered meteorites, implying that aqueous processing changes the mix of amino acids. They also confirmed the enrichment in L-structures of some amino acids, especially isovaline, confirming earlier work. The authors suggest that aqueously-altered planetesimals might have seeded the early Earth with nonracemic amino acids, perhaps explaining why life from microorganisms to people use only L- forms to make proteins. The initial imbalance caused by non-biologic processes in wet asteroids might have been amplified by life on Earth. Alternatively, the same processes that produced the L-amino acid excesses in carbonaceous asteroids also operated on the early Earth.

Taylor, G. J.

2011-04-01

317

Cloud droplet activation of amino acid aerosol particles.  

PubMed

In this work we investigated the ability of a series of amino acids to act as cloud condensation nuclei using a static thermal gradient diffusion type cloud condensation nucleus counter. Particles of pure dry l-glycine, glycyl-glycine, l-serine, l-methionine, l-glutamic acid, l-aspartic acid, and l-tyrosine were studied as well as internally mixed dry particles containing ammonium sulfate and one or two of the following amino acids: l-methionine, l-aspartic acid, or l-tyrosine. The amino acids ranged in water solubility from high (>100 g/L), intermediate (10-100 g/L), low (3-10 g/L), to very low (<3 g/L). With the exception of l-methionine and l-tyrosine, all the studied pure amino acid particles activated as though they were fully soluble, although Kohler theory modified to account for limited solubility suggests that the activation of the intermediate and low solubility amino acids l-serine, l-glutamic acid, and l-aspartic acid should be limited by solubility. Activation of mixed particles containing at least 60% dry mass of l-tyrosine was limited by solubility, but the activation of the other investigated mixed particles behaved as if fully soluble. In general, the results show that particles containing amino acids at atmospherically relevant mixture ratios are good cloud condensation nuclei. PMID:20000558

Kristensson, Adam; Rosen鷨n, Thomas; Bilde, Merete

2010-01-14

318

Amino acid biogeo- and stereochemistry in coastal Chilean sediments  

NASA Astrophysics Data System (ADS)

The spatial distribution of total hydrolysable amino acids (THAA) and amino acid enantiomers ( D- and L-forms) was investigated in sediments underlying two contrasting Chilean upwelling regions: at 23 訕 off Antofagasta and at 36 訕 off Concepci鏮. The contribution of amino acids to total organic carbon (%T AAC: 7-14%) and total nitrogen (%T AAN: 23-38%) in surface sediments decreased with increasing water depth (from 126 to 1350 m) indicating that organic matter becomes increasingly decomposed in surface sediments at greater water depth. Changes in the ratio between the protein amino acid aspartate and its non-protein degradation product ?-alanine confirmed this observation. Furthermore, estimates of THAA mineralization showed that sedimentary amino acid reactivity decreased with both increasing water depth as well as progressive degradation status of the organic matter that was incorporated into the sediment. Reactivity of organic matter in the sediment was also assessed using the Degradation Index (DI) developed by [Dauwe, B., Middelburg, J.J., 1998. Amino acids and hexosamines as indicators of organic matter degradation state in North Sea sediments. Limnol. Oceanogr.43, pp. 782-798.]. Off Concepci鏮, DI was successfully applied to examine the degradation status of sedimentary organic matter at different water depths. However, unexpected results were obtained at the Antofagasta stations as DI increased with sediment depth, suggesting more degraded organic matter at the surface than deeper in the cores. The contribution of peptidoglycan amino acids to THAA was estimated from the concentrations of D-aspartate, D-glutamic acid, D-serine, and D-alanine. Peptidoglycan amino acids accounted for >18% of THAA in all investigated samples. In surface sediments peptidoglycan amino acids accounted for a progressively larger fraction of THAA at increasing water depths (up to >26%). Further, the contribution of peptidoglycan amino acids to THAA increased with increased sediment depth and age (up to 288-year-old) reaching up to 59%. Independent estimates based on D-amino acid concentrations in selected laboratory strains, bacterial counts and the sedimentary concentrations of D-amino acids indicate that a large fraction of the measured D-amino acids (>47 to >97%) originated from cell wall residues rather than from enumerated cells.

Lomstein, Bente Aa.; J鷨gensen, Bo B.; Schubert, Carsten J.; Niggemann, Jutta

2006-06-01

319

Primordial coding of amino acids by adsorbed purine bases.  

PubMed

Scanning tunneling microscopy and chromatography experiments exploring the potential templating properties of nucleic acid bases adsorbed to the surface of crystalline graphite, revealed that the interactions of amino acids with the bare crystal surface are significantly modulated by the prior adsorption of adenine and hypoxanthine. These bases are the coding elements of a putative purine-only genetic alphabet and the observed effects are different for each of the bases. Such mapping between bases and amino acids provides a coding mechanism. These observations demonstrate that a simple pre-RNA amino acid discrimination mechanism could have existed on the prebiotic Earth providing critical functionality for the origin of life. PMID:11889916

Sowerby, Stephen J; Petersen, George B; Holm, Nils G

2002-02-01

320

Primordial Coding of Amino Acids by Adsorbed Purine Bases  

NASA Astrophysics Data System (ADS)

Scanning tunneling microscopy and chromatography experiments exploring the potential templating properties of nucleic acid bases adsorbed to the surface of crystalline graphite, revealed that the interactions of amino acids with the bare crystal surface are significantly modulated by the prior adsorption of adenine and hypoxanthine. These bases are the coding elements of a putative purine-only genetic alphabet and the observed effects are different for each of the bases. Such mapping between bases and amino acids provides a coding mechanism. These observations demonstrate that a simple pre-RNA amino acid discrimination mechanism could have existed on the prebiotic Earth providing critical functionality for the origin of life.

Sowerby, Stephen J.; Petersen, George B.; Holm, Nils G.

2002-02-01

321

Synthesis of Nonproteinogenic Amino Acids to Probe Lantibiotic Biosynthesis  

PubMed Central

The synthesis of six nonproteinogenic amino acids appropriately protected for Fmoc-based solid phase peptide synthesis is described. These amino acids are (2S,3R)-vinylthreonine, (2S)-(E)-2-amino-5-fluoro-pent-3-enoic acid (fluoroallylglycine), (S)-?2-homoserine 3, (S) and (R)-?3-homocysteine, and (2R,3R)-methylcysteine. Once incorporated into peptides, these compounds were envisioned to serve as alternative substrates for the lantibiotic synthases that dehydrate serine and threonine residues in their peptide substrates and catalyze the subsequent intramolecular Michael-type addition of cysteines to the dehydroamino acids.

Zhang, Xingang; Ni, Weijuan; van der Donk, Wilfred A.

2008-01-01

322

Chlamydial Development Is Adversely Affected by Minor Changes in Amino Acid Supply, Blood Plasma Amino Acid Levels, and Glucose Deprivation  

Microsoft Academic Search

This study has demonstrated the extreme sensitivity of Chlamydia trachomatis growing in McCoy cells to small changes in external amino acid supply. In the absence of cycloheximide, a decrease in the amino acid concentration of medium to 75% of control values was sufficient to induce the growth of enlarged chlamydial forms of reduced infectivity. Morphology became more distorted and the

ANGELA HARPER; CHRISTOPHER I. POGSON; MEIRION L. JONES; JOHN H. PEARCE

2000-01-01

323

Growth and Concentrations of Amino Acids in Plasma of Rats Fed Four Levels of Amino Acids '  

Microsoft Academic Search

Amino acids in plasma and liver were measured to determine whether they would reflect dietary intakes of weanling rats fed 4 levels of amino acids in the same proportions when blood was sampled at an interval of fasting at which it was least affected by either absorption or starvation. To determine the interval of fasting to be used, animals fed

CHARLOTTE S. HARKER; PATRICIA E. ALLEN; HELEN E. CLARK

324

Subcritical Water Extraction of Amino Acids from Atacama Desert Soils  

NASA Technical Reports Server (NTRS)

Amino acids are considered organic molecular indicators in the search for extant and extinct life in the Solar System. Extraction of these molecules from a particulate solid matrix, such as Martian regolith, will be critical to their in situ detection and analysis. The goals of this study were to optimize a laboratory amino acid extraction protocol by quantitatively measuring the yields of extracted amino acids as a function of liquid water temperature and sample extraction time and to compare the results to the standard HCl vapor- phase hydrolysis yields for the same soil samples. Soil samples from the Yungay region of the Atacama Desert ( Martian regolith analog) were collected during a field study in the summer of 2005. The amino acids ( alanine, aspartic acid, glutamic acid, glycine, serine, and valine) chosen for analysis were present in the samples at concentrations of 1 - 70 parts- per- billion. Subcritical water extraction efficiency was examined over the temperature range of 30 - 325 degrees C, at pressures of 17.2 or 20.0 MPa, and for water- sample contact equilibration times of 0 - 30 min. None of the amino acids were extracted in detectable amounts at 30 degrees C ( at 17.2 MPa), suggesting that amino acids are too strongly bound by the soil matrix to be extracted at such a low temperature. Between 150 degrees C and 250 degrees C ( at 17.2 MPa), the extraction efficiencies of glycine, alanine, and valine were observed to increase with increasing water temperature, consistent with higher solubility at higher temperatures, perhaps due to the decreasing dielectric constant of water. Amino acids were not detected in extracts collected at 325 degrees C ( at 20.0 MPa), probably due to amino acid decomposition at this temperature. The optimal subcritical water extraction conditions for these amino acids from Atacama Desert soils were achieved at 200 degrees C, 17.2 MPa, and a water- sample contact equilibration time of 10 min.

Amashukeli, Xenia; Pelletier, Christine C.; Kirby, James P.; Grunthaner, Frank J.

2007-01-01

325

Influence of amino acids on okadaic acid production.  

PubMed

Okadaic acid (OA) (1)) was the first example of a group of polyether toxins known to be produced by marine microalgae, which are responsible for the natural phenomena known as Diarrhetic Shellfish Poisoning (DSP) red tides. It is also a highly selective inhibitor of protein phosphatases type 1 (PP1) and 2A (PP2A), as well as being a potent tumour promoter. For these reasons, OA is an extremely useful tool for studying cellular processes and an important standard for polluted shellfish control. In this paper, we report on a double objective: to improve the production of toxins and verify the apparent participation of amino acids in the formation of these polyethers by monitoring their influence on the promotion of growth, total cell yield and increased in toxicity in Prorocentrum lima of the PL2V strain in batch cultures, in a modified K medium. PMID:11072044

Souto, M L; Fern嫕dez, J J; Norte, M; Fern嫕dez, M L; Mart璯ez, A

2001-05-01

326

Quantitative and qualitative changes in plasma amino nitrogen and amino acids during haemodialysis  

Microsoft Academic Search

SummaryTwenty-one patients undergoing haemodialysis on a coil dialyser were investigated for quantitative and qualitative changes\\u000a in plasma alpha amino nitrogen and amino acids. Blood samples obtained at the beginning and following the termination of dialysis\\u000a were analysed. There was an average fall of 29% in the level of circulating amino nitrogen during dialysis. In addition repeated\\u000a dialysis resulted in a

G. D. Doyle; W. F. ODwyer; M. Carmody; V. Gallagher

1924-01-01

327

Indispensable amino acid concentrations decrease in tissues of stomachless fish, common carp in response to free amino acid- or peptide-based diets.  

PubMed

The premise that free amino acid or dipeptide based diets will resolve the nutritional inadequacy of formulated feeds for larval and juvenile fish and improve utilization of nitrogen in comparison to protein-based diets was tested in stomachless fish, common carp (Cyprinus carpio L.) larvae. We examined the postprandial whole body free amino acid (FAA) pool in fish that were offered a FAA mixture based diet for the duration of 2 or 4 weeks. We found that the total amount and all indispensable amino acids concentrations in the whole body decreased after a meal. We then fed juvenile carp with dietary amino acids provided in the FAA, dipeptide (PP), or protein (live feed organisms; brine shrimp Artemia salina nauplii, AS) forms. Histidine concentrations in the whole fish body increased in all dietary groups after feeding whereas all other indispensable amino acids decreased in FAA and PP groups in comparison to the AS group. Taurine appears to be the major osmotic pressure balancing free amino acid in larval freshwater fish which may indicate a conditional requirement. We present the first evidence in larval fish that in response to synthetic FAA and PP diets, the whole body indispensable free AA concentrations decreased after feeding. This study shows that amino acids given entirely as FAA or PP cannot sustain stomachless larval fish growth, and may result in depletion of body indispensable AA and most of dispensable AA. The understanding of these responses will determine necessary changes in diet formulations that prevent accelerated excretion of amino acids without protein synthesis. PMID:16733614

Zhang, Y; Dabrowski, K; Hliwa, P; Gomulka, P

2006-09-01

328

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

329

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.

Macnicol, Peter K.

1983-01-01

330

7 Regulation of the yeast general amino acid control pathway in response to nutrient stress  

Microsoft Academic Search

In response to starvation for amino acids, yeast cells induce the expression of a collection of genes involved in amino acid metabolism. This pathway referred to as the general amino acid control is a true cross-pathway response that induces expression of genes contributing to the synthesis of all amino acids independent of which amino acid is limiting. In this review,

Ronald C. Wek; Kirk A. Staschke; Jana Narasimhan

331

Amino Acid Synthesis in a Supercritical Carbon Dioxide - Water System  

PubMed Central

Mars is a CO2-abundant planet, whereas early Earth is thought to be also CO2-abundant. In addition, water was also discovered on Mars in 2008. From the facts and theory, we assumed that soda fountains were present on both planets, and this affected amino acid synthesis. Here, using a supercritical CO2/liquid H2O (10:1) system which mimicked crust soda fountains, we demonstrate production of amino acids from hydroxylamine (nitrogen source) and keto acids (oxylic acid sources). In this research, several amino acids were detected with an amino acid analyzer. Moreover, alanine polymers were detected with LC-MS. Our research lights up a new pathway in the study of lifes origin.

Fujioka, Kouki; Futamura, Yasuhiro; Shiohara, Tomoo; Hoshino, Akiyoshi; Kanaya, Fumihide; Manome, Yoshinobu; Yamamoto, Kenji

2009-01-01

332

Telomerization of amino acids with butadiene, catalyzed by palladium complexes  

SciTech Connect

The telomerization of ..cap alpha..-, ..beta..-, ..gamma..-, and epsilon-amino acids having various structures with butadiene under the influence of the three-component palladium catalyst Pd(acac)/sub 2/-PPh/sub 3/-AlEt/sub 3/ was investigated in DMSO-toluene solution. The ..cap alpha..- and epsilon-aliphatic and also the ..cap alpha..-, ..beta..-, and ..gamma..-aromatic amino acids react with butadiene, giving the products from octadienylation at the amino group exclusively. Under the conditions of telomerization aliphatic ..beta..-amino acids are cleaved with the formation of unsaturated tertiary amines. In the case of aliphatic ..gamma..-amino acids it is possible to obtain telomers alkylated at the carbonyl group.

Dzhemilev, U.M.; Fakhretdinov, R.N.; Telin, A.G.

1987-01-10

333

Transaminases for the synthesis of enantiopure beta-amino acids  

PubMed Central

Optically pure ?-amino acids constitute interesting building blocks for peptidomimetics and a great variety of pharmaceutically important compounds. Their efficient synthesis still poses a major challenge. Transaminases (also known as aminotransferases) possess a great potential for the synthesis of optically pure ?-amino acids. These pyridoxal 5'-dependent enzymes catalyze the transfer of an amino group from a donor substrate to an acceptor, thus enabling the synthesis of a wide variety of chiral amines and amino acids. Transaminases can be applied either for the kinetic resolution of racemic compounds or the asymmetric synthesis starting from a prochiral substrate. This review gives an overview over microbial transaminases with activity towards ?-amino acids and their substrate spectra. It also outlines current strategies for the screening of new biocatalysts. Particular emphasis is placed on activity assays which are applicable to high-throughput screening.

2012-01-01

334

Amino acid regions 572-579 and 657-666 of the spacer domain of ADAMTS 13 provide a common antigenic core required for binding of antibodies in patients with acquired TTP  

Microsoft Academic Search

Antibodies directed against ADAMTS13 have been detected in the majority of patients with acquired thrombotic thrombocytopenic purpura (TTP). We have previously localized a major antigenic determinant within the spacer domain of ADAMTS13. To identify the amino acid residues of the spacer domain that are involved in binding of anti-ADAMTS13 antibodies, we constructed a series of fifteen hybrids (designated A-O) in

Brenda M. Luken; Ellen A. M. Turenhout; Paul H. P. Kaijen; Mascha J. Greuter; Wouter Pos; Mourik van J. A; Rob Fijnheer; Jan Voorberg

2006-01-01

335

Derivatives of aminoquinones with N-protected amino acids  

Microsoft Academic Search

SummaryThe synthesis of derivatives of aminoquinones with N-protected amino acids is reported here. 2-Amino-1,4-benzoquinone and\\u000a 2-amino-1,4-naphthoquinone, prepared by the azide method in yields of 60 and 95% respectively, were coupled with N-Boc-protected\\u000a amino acids including glycine, serine, proline and tyrosine, to give the correspondening derivatives.N, N?-Diisopropylcarbodiimide\\/1-hydroxybenzotriazole orN, N?-dicyclohexylcarbodiimide\\/HOBt used as coupling reagents provided the expected products in satisfactory yields and

Chrysostomos Pachatouridis; Elias A. Couladouros; Vassilios P. Papageorgiou; Maria Liakopoulou-Kyriakides

1998-01-01

336

Derivatives of Aminoquinones with N-protected Amino Acids  

Microsoft Academic Search

The synthesis of derivatives of aminoquinones with N-protected amino acids is reported here. 2-Amino-1,4-benzoquinone and 2-amino-1,4-naphthoquinone, prepared by the azide method in yields of 60 and 95% respectively, were coupled with N-Boc-protected amino acids including glycine, serine, proline and tyrosine, to give the correspondening derivatives. N,N'-Diisopropylcarbodiimide\\/1-hydroxybenzotriazole or N,N'-dicyclohexylcarbodiimide\\/HOBt used as coupling reagents provided the expected products in satisfactory yields and

Chrysostomos Pachatouridis; Elias A. Couladouros; Vassilios P. Papageorgiou

1998-01-01

337

An increase in essential amino acid availability upregulates amino acid transporter expression in human skeletal muscle  

PubMed Central

Essential amino acids (EAA) stimulate skeletal muscle mammalian target of rapamycin complex 1 (mTORC1) signaling and protein synthesis. It has recently been reported that an increase in amino acid (AA) transporter expression during anabolic conditions is rapamycin-sensitive. The purpose of this study was to determine whether an increase in EAA availability increases AA transporter expression in human skeletal muscle. Muscle biopsies were obtained from the vastus lateralis of seven young adult subjects (3 male, 4 female) before and 13 h after EAA ingestion (10 g). Blood and muscle samples were analyzed for leucine kinetics using stable isotopic techniques. Quantitative RT-PCR, and immunoblotting were used to determine the mRNA and protein expression, respectively, of AA transporters and members of the general AA control pathway [general control nonrepressed (GCN2), activating transcription factor (ATF4), and eukaryotic initiation factor (eIF2) ?-subunit (Ser52)]. EAA ingestion increased blood leucine concentration, delivery of leucine to muscle, transport of leucine from blood into muscle, intracellular muscle leucine concentration, ribosomal protein S6 (Ser240/244) phosphorylation, and muscle protein synthesis. This was followed with increased L-type AA transporter (LAT1), CD98, sodium-coupled neutral AA transporter (SNAT2), and proton-coupled amino acid transporter (PAT1) mRNA expression at 1 h (P < 0.05) and modest increases in LAT1 protein expression (3 h post-EAA) and SNAT2 protein expression (2 and 3 h post-EAA, P < 0.05). Although there were no changes in GCN2 expression and eIF2? phosphorylation, ATF4 protein expression reached significance by 2 h post-EAA (P < 0.05). We conclude that an increase in EAA availability upregulates human skeletal muscle AA transporter expression, perhaps in an mTORC1-dependent manner, which may be an adaptive response necessary for improved AA intracellular delivery.

Drummond, Micah J.; Glynn, Erin L.; Fry, Christopher S.; Timmerman, Kyle L.; Volpi, Elena

2010-01-01

338

Discovery of amino acid amides as new substrates for ?-amino-?-caprolactam racemase from Achromobacter obae  

Microsoft Academic Search

Amino acid amide racemizing activity was discovered in ?-amino-?-caprolactam (ACL) racemase (EC 5. 1. 1. 15) from Achromobacter obae. The nucleotide sequence of 1305bp ACL racemase gene was designed for expression in Escherichia coli and synthesized in a reaction with 46 oligonucleotides by assembly PCR technique. The gene was expressed under the control of the lac promoter, and ACL racemase

Yasuhisa Asano; Shigenori Yamaguchi

2005-01-01

339

Discovery of amino acid amides as new substrates for -amino--caprolactam racemase from Achromobacter obae  

Microsoft Academic Search

Amino acid amide racemizing activity was discovered in -amino--caprolactam (ACL) racemase (EC 5. 1. 1. 15) from Achromobacter obae. The nucleotide sequence of 1305 bp ACL racemase gene was designed for expression in Escherichia coli and synthesized in a reaction with 46 oligonucleotides by assembly PCR technique. The gene was expressed under the control of the lac promoter, and ACL

Yasuhisa Asano; Shigenori Yamaguchi

340

Effect of Cortisol on Growth, Food Intake, Dietary Preference and Plasma Amino Acid Pattern of Rats Fed Amino Acid Imbalanced Diets  

Microsoft Academic Search

Since cortisol is known to influence plasma amino acid concentrations and amino acid metabolism in general, rats fed amino acid unbalanced diets have been given cortisol, and growth, food intake, dietary choice and plasma amino acid concentrations have been measured. Food intake and growth of rats fed a threonine- or a histidine-imbalanced diet were depressed. However, food intakes of rats

PHILIP M.-B. LEUNG; QUINTON R. ROGERS ANDA; E. HARPER

2010-01-01

341

Isotopic analyses of amino acids from the Murchison meteorite  

SciTech Connect

Previous isotopic analyses of the total amino acids of the Murchison meteorite showed these compounds to be substantially enriched in {sup 2}H, {sup 13}C, and {sup 15}N relative to terrestrial organic matter. These analyses have been repeated ({sup 2}H, {sup 13}C) with inclusion of an ultrafiltration step to exclude the possibility that a fine particulate contaminant carried the isotopic excesses observed in the previous work. In addition, the meteorite amino acids were chromatographically separated to rule out the possibility that the isotopic enrichment of the meteorite extract could reside in basic compounds other than amino acids. The results indicate that the Murchison amino acids are truly isotopically unusual, that the isotopic excesses reside in at least several different amino acids, and that the isotopic contents of some of these amino acids reach values of about +40{per thousand} ({delta}{sup 13}C) and +2,500{per thousand} ({delta}D). If it is assumed that the high deuterium content of the meteroite {alpha}-amino acids is a result of the synthesis of their molecular precursors by low temperature ion-molecule reactions in an interstellar cloud, their formation by aqueous phase Strecker reactions in the parent body is consistent with their general characteristics and with known parent body processes.

Pizzarello, S.; Cronin, J.R. (Arizona State Univ., Tempe (United States)); Krishnamurthy, R.V.; Epstein, S. (California Inst. of Tech., Pasadena, CA (United States))

1991-03-01

342

Designing amino acids to determine the local conformations of peptides.  

PubMed Central

The local conformations of proteins and peptides are determined by the amino acid sequence. However, the 20 amino acids encoded by the genome allow the peptide backbone to fold into many conformations, so that even for a small peptide it becomes very difficult to predict the three-dimensional structure. By using empirical conformational energy calculations, a set of amino acids has been designed that would be expected to constrain the conformation of a peptide or a protein to one or two local minima. Most of these amino acids are based on asymmetric substitutions at the C alpha atom of each residue. The H alpha atom of alanine was replaced by various groups: -OCH3, -NCH3, -SCH3, -CONH2, -CONHCH3, -CON(CH3)2, -NH.CO.CH3, -phenyl, or -o-(OCH3)phenyl. Several of these new amino acids are predicted to fold into unique peptide conformations such as right-handed alpha-helical, left-handed alpha-helical, or extended. In an attempt to produce an amino acid that favored the C(eq)7 conformation (torsion angles: phi = -70 degrees and psi = +70 degrees), an extra amide group was added to the C beta atom of the asparagine side chain. Conformationally restricted amino acids of this type could prove useful for developing new peptide pharmaceuticals, catalysts, or polymers. Images

Burgess, A W

1994-01-01

343

The Fate of Amino Acids During Simulated Meteoritic Impact  

NASA Astrophysics Data System (ADS)

Delivery of prebiotic molecules, such as amino acids and peptides, in meteoritic/micrometeoritic materials to early Earth during the first 500 million years is considered to be one of the main processes by which the building blocks of life arrived on Earth. In this context, we present a study in which the effects of impact shock on amino acids and a peptide in artificial meteorites composed of saponite clay were investigated. The samples were subjected to pressures ranging from 12-28.9 GPa, which simulated impact velocities of 2.4-5.8 km/s for typical silicate-silicate impacts on Earth. Volatilization was determined by weight loss measurement, and the amino acid and peptide response was analyzed by gas chromatography-mass spectrometry. For all compounds, degradation increased with peak pressure. At the highest shock pressures, amino acids with an alkyl side chain were more resistant than those with functional side chains. The peptide cleaved into its two primary amino acids. Some chiral amino acids experienced partial racemization during the course of the experiment. Our data indicate that impact shock may act as a selective filter to the delivery of extraterrestrial amino acids via carbonaceous chondrites.

Bertrand, Maryl鋝e; van der Gaast, Sjerry; Vilas, Faith; H顤z, Friedrich; Haynes, Gerald; Chabin, Annie; Brack, Andre; Westall, Frances

2009-12-01

344

Amino acid signatures in the developing mouse retina.  

PubMed

This study characterizes the developmental patterns of seven key amino acids: glutamate, ?-amino-butyric acid (GABA), glycine, glutamine, aspartate, alanine and taurine in the mouse retina. We analyze amino acids in specific bipolar, amacrine and ganglion cell sub-populations (i.e. GABAergic vs. glycinergic amacrine cells) and anatomically distinct regions of photoreceptors and Mller cells (i.e. cell bodies vs. endfeet) by extracting data from previously described pattern recognition analysis. Pattern recognition statistically classifies all cells in the retina based on their neurochemical profile and surpasses the previous limitations of anatomical and morphological identification of cells in the immature retina. We found that the GABA and glycine cellular content reached adult-like levels in most neurons before glutamate. The metabolic amino acids glutamine, aspartate and alanine also reached maturity in most retinal cells before eye opening. When the overall amino acid profiles were considered for each cell group, ganglion cells and GABAergic amacrine cells matured first, followed by glycinergic amacrine cells and finally bipolar cells. Photoreceptor cell bodies reached adult-like amino acid profiles at P7 whilst Mller cells acquired typical amino acid profiles in their cell bodies at P7 and in their endfeet by P14. We further compared the amino acid profiles of the C57Bl/6J mouse with the transgenic X-inactivation mouse carrying the lacZ gene on the X chromosome and validated this animal model for the study of normal retinal development. This study provides valuable insight into normal retinal neurochemical maturation and metabolism and benchmark amino acid values for comparison with retinal disease, particularly those which occur during development. PMID:24368173

Nivison-Smith, Lisa; Chua, Jacqueline; Tan, Seong-Seng; Kalloniatis, Michael

2014-04-01

345

Microbial Products Trigger Amino Acid Exudation from Plant Roots1  

PubMed Central

Plants naturally cycle amino acids across root cell plasma membranes, and any net efflux is termed exudation. The dominant ecological view is that microorganisms and roots passively compete for amino acids in the soil solution, yet the innate capacity of roots to recover amino acids present in ecologically relevant concentrations is unknown. We find that, in the absence of culturable microorganisms, the influx rates of 16 amino acids (each supplied at 2.5 ?m) exceed efflux rates by 5% to 545% in roots of alfalfa (Medicago sativa), Medicago truncatula, maize (Zea mays), and wheat (Triticum aestivum). Several microbial products, which are produced by common soil microorganisms such as Pseudomonas bacteria and Fusarium fungi, significantly enhanced the net efflux (i.e. exudation) of amino acids from roots of these four plant species. In alfalfa, treating roots with 200 ?m phenazine, 2,4-diacetylphloroglucinol, or zearalenone increased total net efflux of 16 amino acids 200% to 2,600% in 3 h. Data from 15N tests suggest that 2,4-diacetylphloroglucinol blocks amino acid uptake, whereas zearalenone enhances efflux. Thus, amino acid exudation under normal conditions is a phenomenon that probably reflects both active manipulation and passive uptake by microorganisms, as well as diffusion and adsorption to soil, all of which help overcome the innate capacity of plant roots to reabsorb amino acids. The importance of identifying potential enhancers of root exudation lies in understanding that such compounds may represent regulatory linkages between the larger soil food web and the internal carbon metabolism of the plant.

Phillips, Donald A.; Fox, Tama C.; King, Maria D.; Bhuvaneswari, T.V.; Teuber, Larry R.

2004-01-01

346

Root uptake of cationic amino acids by Arabidopsis depends on functional expression of amino acid permease 5.  

PubMed

* Specific transporters mediate uptake of amino acids by plant roots. Earlier studies have indicated that the lysine histidine transporter 1 and amino acid permease 1 participate in this process, but although plant roots have been shown to absorb cationic amino acids with high affinity, neither of these transporters seems to mediate transport of L-arginine (L-Arg) or L-lysine (L-Lys). * Here, a collection of T-DNA knockout mutants were screened for alterations in Arabidopsis root uptake rates of L-Arg and it was found that only the AAP5 mutant displayed clear phenotypic divergence on high concentrations of L-Arg. A second screen using low concentrations of (15)N-labelled L-Arg in the growth media also identified AAP5 as being involved in L-Arg acquisition. * Momentaneous root uptake of basic amino acids was strongly affected in AAP5 mutant lines, but their uptake of other types of amino acids was only marginally affected. Comparisons of the root uptake characteristics of AAP5 and LHT1 mutants corroborated the hypothesis that the two transporters have distinct affinity spectra in planta. * Root uptake of all tested amino acids, except L-aspartic acid (L-Asp), was significantly affected in double AAP5*LHT1 mutants, suggesting that these two transporters account for a major proportion of roots' uptake of amino acids at low concentrations. PMID:18681934

Svennerstam, Henrik; Ganeteg, Ulrika; N酲holm, Torgny

2008-01-01

347

Formation of proline thiohydantoin with ammonium thiocyanate: progress towards a viable C-terminal amino-acid-sequencing procedure.  

PubMed

Pure amino acid thiohydantoins are required as reference standards for development of C-terminal-sequencing procedures based on thiohydantoin formation of the C-terminal amino acids of peptides and proteins. Proline thiohydantoin was prepared using a straightforward method involving reaction of acetylproline with ammonium thiocyanate. It was characterized by UV spectrophotometry, mass spectrometry and back-hydrolysis to the free amino acid. These data establish unequivocally that the thiocyanate procedure is applicable to proline as well as to the other common amino acids. This work also validates earlier claims that proline thiohydantoin can be prepared by reaction with thiocyanic acid. PMID:1491101

Inglis, A S; Duncan, M W; Adams, P; Tseng, A

1992-10-01

348

Determination of 2Keto Acids and Amino Acids in Plant Extracts  

Microsoft Academic Search

2-keto acids and amino acids were extracted using liquid nitrogen and 0.25 N HCl. The keto acids and amino acids were seperated by cation exchange chromatography on AG50W-X8 resin. The cation exchange chromatography is vital for the determination of keto acids. The keto acids were derivatized with 1,2-diamino-4,5-methylenedioxybenzene (DMB), a specific derivatizing agent for 2-keto acids. The derivatized keto acids

Bijay K. Singh; Berhane Tecle; Dale L. Shaner

1994-01-01

349

Exhaustive Database Searching for Amino Acid Mutations in Proteomes  

SciTech Connect

Amino acid mutations in proteins can be found by searching tandem mass spectra acquired in shotgun proteomics experiments against protein sequences predicted from genomes. Traditionally, unconstrained searches for amino acid mutations have been accomplished by using a sequence tagging approach that combines de novo sequencing with database searching. However, this approach is limited by the performance of de novo sequencing. The Sipros algorithm v2.0 was developed to perform unconstrained database searching using high-resolution tandem mass spectra by exhaustively enumerating all single non-isobaric mutations for every residue in a protein database. The performance of Sipros for amino acid mutation identification exceeded that of an established sequence tagging algorithm, Inspect, based on benchmarking results from a Rhodopseudomonas palustris proteomics dataset. To demonstrate the viability of the algorithm for meta-proteomics, Sipros was used to identify amino acid mutations in a natural microbial community in acid mine drainage.

Hyatt, Philip Douglas [ORNL; Pan, Chongle [ORNL

2012-01-01

350

[Adducts of glycosylated serum albumin with amino acids].  

PubMed

Glycosylation of human serum albumin was conducted by its long incubation with the excess either of D-glucose or D-glucose-6-phosphate at 37 degrees C. The glycosylated fractions were isolated by the cation-exchange chromatography on CM-cellulose. The quantity of glucose bound covalently with protein was determined by thiobarbituric acid. The glucose-modified human serum albumin forms stable adducts with amino acids. These complexes are, evidently, produced as a result of the Schiff's base formation between the carbonyl group of the ketoamine adduct of glucose with protein and primary amino group of amino acid further followed by the Amadori rearrangement. PMID:3739039

Stepuro, I I; Piletskaia, T P; Iaroshevich, N A; Naumov, A V

1986-01-01

351

SIFT: Predicting amino acid changes that affect protein function.  

PubMed

Single nucleotide polymorphism (SNP) studies and random mutagenesis projects identify amino acid substitutions in protein-coding regions. Each substitution has the potential to affect protein function. SIFT (Sorting Intolerant From Tolerant) is a program that predicts whether an amino acid substitution affects protein function so that users can prioritize substitutions for further study. We have shown that SIFT can distinguish between functionally neutral and deleterious amino acid changes in mutagenesis studies and on human polymorphisms. SIFT is available at http://blocks.fhcrc.org/sift/SIFT.html. PMID:12824425

Ng, Pauline C; Henikoff, Steven

2003-07-01

352

Double amino acid A novel molecule enabling peptide interpenetrating structures  

NASA Astrophysics Data System (ADS)

Peptide chains might be linked with one another using various external bifunctional molecules. We postulate an existence of a novel molecule termed double amino acid' containing four functional groups connected to one C atom ((NH2)2C(COOH)2). Using correlated ab initio approach (QCISD and MP2 methods) we provide its structure, simulated IR spectrum and verify its stability in gas and aqueous phases. The proposed double amino acid is predicted to enable the design of a novel family of interpenetrating peptides in which it is expected to serve as a built-in amino acid residue that might be shared by two independent peptide chains.

Freza, Sylwia; Marchaj, Marzena; Skurski, Piotr

2014-04-01

353

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

354

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

355

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

356

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 禮 721.10380 Benzoic acid, 3-amino-2-mercapto-. (a) Chemical...substance identified as benzoic acid, 3-amino-2-mercapto- (PMN...

2013-07-01

357

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

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Amino acid, carboxyalkyl, alkylsulfonate...Substances 禮 721.10630 Amino acid, carboxyalkyl, alkylsulfonate...identified generically as amino acid, carboxyalkyl, alkylsulfonate...subtracted in calculating the number of kilograms released....

2013-07-01

358

"Extreme" Ugi reactions with some complex ?-amino acids.  

PubMed

The Ti(IV)-catalyzed Ugi condensation of ?-amino acids with electron-rich aromatic aldehydes performs adequately even with sterically demanding ?-amino carboxylate salts. The reaction occurs diastereoselectively, in some cases with virtually complete diastereoselectivity. A stereochemical rationale for the reaction is proposed. PMID:22954286

Turner, Charles Dylan; Ciufolini, Marco A

2012-09-21

359

Bidirectional modulation of insulin action by amino acids.  

PubMed Central

Amino acids have been shown to stimulate protein synthesis, inhibit proteolysis, and decrease whole-body and forearm glucose disposal. Using cultured hepatoma and myotube cells, we demonstrate that amino acids act as novel signaling elements in insulin target tissues. Exposure of cells to high physiologic concentrations of amino acids activates intermediates important in the initiation of protein synthesis, including p70 S6 kinase and PHAS-I, in synergy with insulin. This stimulatory effect is largely due to branched chain amino acids, particularly leucine, and can be reproduced by its transamination product, ketoisocaproic acid. Concurrently, amino acids inhibit early steps in insulin action critical for glucose transport and inhibition of gluconeogenesis, including decreased insulin-stimulated tyrosine phosphorylation of IRS-1 and IRS-2, decreased binding of grb 2 and the p85 subunit of phosphatidylinositol 3-kinase to IRS-1 and IRS-2, and a marked inhibition of insulin-stimulated phosphatidylinositol 3-kinase. Taken together, these data support the hypothesis that amino acids act as specific positive signals for maintenance of protein stores, while inhibiting other actions of insulin at multiple levels. This bidirectional modulation of insulin action indicates crosstalk between hormonal and nutritional signals and demonstrates a novel mechanism by which nutritional factors contribute to insulin resistance.

Patti, M E; Brambilla, E; Luzi, L; Landaker, E J; Kahn, C R

1998-01-01

360

The Amino Acid Composition of the Sutter's Mill Carbonaceous Chondrite  

NASA Technical Reports Server (NTRS)

In contrast to the Murchison meteorite which had a complex distribution of amino acids with a total C2 to Cs amino acid abundance of approx.14,000 parts-per-billion (ppb) [2], the Sutters Mill meteorite was found to be highly depleted in amino acids. Much lower abundances (approx.30 to 180 ppb) of glycine, beta-alanine, L-alanine and L-serine were detected in SM2 above procedural blank levels indicating that this meteorite sample experienced only minimal terrestrial amino acid contamination after its fall to Earth. Carbon isotope measurements will be necessary to establish the origin of glycine and beta-alanine in SM2. Other non-protein amino acids that are rare on Earth, yet commonly found in other CM meteorites such as aaminoisobutyric acid (alpha-AIB) and isovaline, were not identified in SM2. However, traces of beta-AIB (approx.1 ppb) were detected in SM2 and could be" extraterrestrial in origin. The low abundances of amino acids in the Sutter's Mill meteorite is consistent with mineralogical evidence that at least some parts of the Sutter's Mill meteorite parent body experienced extensive aqueous and/or thermal alteration.

Glavin, D. P.; Burton, A. S.; Elsila, J. E.; Dworkin, J. P.; Yin, Q. Z.; Cooper, G.; Jenniskens, P.

2012-01-01

361

Synthesis of Some Novel Benzylidenehydantoins: Amino Acids Derivatives  

Microsoft Academic Search

5-Benzylidenehydantoin reacts with chlorosulfonic acid to give the corresponding p-sulfonyl chloride. Condensation of the latter with amino acids leads to sulfonylamino acid derivatives, which on coupling with glycine methyl ester hydrochloride in THF-Et3N using the dicyclohexylcarbodiimide method furnish the desired dipeptide methyl esters. The spectral data of the compounds are briefly discussed.

Ragab A. El-Sayed

2001-01-01

362

Some Novel Sulfanilyl Amino Acids and Dipeptides Derivatives  

Microsoft Academic Search

3-(N-phenylcarboxamido)-coumarin 1 reacted with chlorosulfonic acid to give the corresponding sulfaniyl chloride 2. However, isonicotinic acid anilide 14, and nicotinic acid anilide 33, reacted with chlorosulfonic acid in a 1:6 molar ratio, only for conversion into sulfanilyl chlorides 15 and 34. Treatment with nucleophilic reagents afforded amino acid derivatives 36, 1620, and 3537. Some of the corresponding methyl esters 79,

Ragab A. El-Sayed

2007-01-01

363

Principal transcriptional regulation and genome-wide system interactions of the Asp-family and aromatic amino acid networks of amino acid metabolism in plants.  

PubMed

Amino acid metabolism is among the most important and best recognized networks within biological systems. In plants, amino acids serve multiple functions associated with growth. Besides their function in protein synthesis, the amino acids are also catabolized into energy-associated metabolites as well we into numerous secondary metabolites, which are essential for plant growth and response to various stresses. Despite the central importance of amino acids in plants growth, elucidation of the regulation of amino acid metabolism within the context of the entire system, particularly transcriptional regulation, is still in its infancy. The different amino acids are synthesized by a number of distinct metabolic networks, which are expected to possess regulatory cross interactions between them for proper coordination of their interactive functions, such as incorporation into proteins. Yet, individual amino acid metabolic networks are also expected to differentially cross interact with various genome-wide gene expression programs and metabolic networks, in respect to their functions as precursors for various metabolites with distinct functions. In the present review, we discuss our recent genomics, metabolic and bioinformatics studies, which were aimed at addressing these questions, focusing mainly on the Asp-family metabolic network as the main example and also comparing it to the aromatic amino acids metabolic network as a second example (Angelovici et al. in Plant Physiol 151:2058-2072, 2009; Less and Galili in BMC Syst Biol 3:14, 2009; Tzin et al. in Plant J 60:156-167, 2009). Our focus on these two networks is because of the followings: (i) both networks are central to plant metabolism and growth and are also precursors for a wide range of primary and secondary metabolites that are indispensable to plant growth; (ii) the amino acids produced by these two networks are also essential to the nutrition and health of human and farm animals; and (iii) both networks contain branched pathways requiring extensive regulation of fluxes between the different branches. Additional views on the biochemistry, regulation and functional significance of the Asp-family and aromatic amino acid networks and some of their associated metabolites that are discussed in the present report, as well as the nutritional importance of Lys and Trp to human and farm animals, and attempts to improve Lys level in crop plants, can be obtained from the following reviews as examples (Radwanski and Last in Plant Cell 7:921-934, 1995; Halkier and Gershenzon in Annu Rev Plant Biol 57:303-333, 2006; Ufaz and Galili in Plant Physiol 147:954-961, 2008; Jander and Joshi in Mol Plant 3:54-65, 2010). PMID:20364431

Less, Hadar; Angelovici, Ruthie; Tzin, Vered; Galili, Gad

2010-10-01

364

Growth Response of Nitrosomonas europaea to Amino Acids  

PubMed Central

Growth responses of Nitrosomonas europaea to individual amino acids or vitamins was observed in log-phase cultures, as was the incorporation of carbon-14 labeled amino acids. Nitrite formation and protein synthesis were increased by l-glutamic acid, l-aspartic acid, l-serine, and l-glutamine. l-Lysine, l-histidine, l-threonine, l-valine, l-methionine, and l-arginine were inhibitory. The other amino acids had no effect on growth. All of the uniformly labeled amino acids added at low concentrations were taken up by growing cells and distributed into cell fractions. From 1 to 12% of the added radioactivity was present in cells analyzed in late log phase, depending on the amino acid; glycine and l-serine caused accumulation of the label to the greatest extent, whereas l-aspartic and l-glutamic acids were among those incorporated to the least extent. Aspartic acid increased both cell protein and nitrite values, but did not alter the ratio of protein to nitrite from that found in controls.

Clark, Connie; Schmidt, E. L.

1967-01-01

365

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).

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

2014-01-01

366

Amino acid signalling upstream of mTOR.  

PubMed

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

2013-03-01

367

Reconstructing a Flavodoxin Oxidoreductase with Early Amino Acids  

PubMed Central

Primitive proteins are proposed to have utilized organic cofactors more frequently than transition metals in redox reactions. Thus, an experimental validation on whether a protein constituted solely by early amino acids and an organic cofactor can perform electron transfer activity is an urgent challenge. In this paper, by substituting late amino acids (C, F, M, T, W, and Y) with early amino acids (A, L, and V) in a flavodoxin, we constructed a flavodoxin mutant and evaluated its characteristic properties. The major results showed that: (1) The flavodoxin mutant has structural characteristics similar to wild-type protein; (2) Although the semiquinone and hydroquinone flavodoxin mutants possess lower stability than the corresponding form of wild-type flavodoxin, the redox potential of double electron reduction Em,7 (fld) reached ?360 mV, indicating that the flavodoxin mutant constituted solely by early amino acids can exert effective electron transfer activity.

Lu, Ming-Feng; Ji, Hong-Fang; Li, Ting-Xuan; Kang, Shou-Kai; Zhang, Yue-Jie; Zheng, Jue-Fei; Tian, Tian; Jia, Xi-Shuai; Lin, Xing-Ming; Zhang, Hong-Yu

2013-01-01

368

Differential adhesion of amino acids to inorganic surfaces  

PubMed Central

A fundamental, yet underexplored, materials system is the interface between biological molecules and inorganic surfaces. In an elemental approach to this problem, we have systematically examined the adhesion of amino acids to a series of inorganic surfaces including metals, insulators, and semiconductors. Significant differential adhesion is observed over the full complement of amino acids, determined largely by amino acid side-chain charge. Extensive mapping of the amino acid adhesion versus materials in multiple solutions is presented, with preliminary mechanisms derived from concentration and pH dependence. These results provide an empirical basis for building peptide to inorganic surface structures, and, using this adhesion data, we design inorganic nanostructures that are shown to selectively bind to prescribed primary peptide sequences.

Willett, R. L.; Baldwin, K. W.; West, K. W.; Pfeiffer, L. N.

2005-01-01

369

Gas Chromatographic Confirmation of Amino Acid Structure via Diastereomer Preparation.  

National Technical Information Service (NTIS)

The partial gas chromatographic (GC) resolution of several amino acid N-trifluoroacetyl 2-butyl ester diastereomeric derivatives on a short packed column has been used to confirm GC peak assignments in analysis of a marine sediment sample. (Author)

J. K. Whelan

1974-01-01

370

Utilization of Free and Combined Amino Acids by Activated Sludge.  

National Technical Information Service (NTIS)

The research is concerned with utilization of nitrogen in the form of amino acids both singly and bound together in peptides and proteins. Such proteinaceous materials comprise the major nitrogen fraction in domestic sewage and, hence, studies on optimum ...

D. A. Carlson

1965-01-01

371

Stereospecific Chemical Sensors for Amino Acids and Carbohydrates  

NASA Astrophysics Data System (ADS)

Specific organic compounds, such as amino acids and carbohydrates, are attractive targets as biomarkers We are developing sensors based on a family of proteins that bind specific analytes with stereochemical specificity to measure enantiomeric excesses in these biomarkers.

Paavola, C. D.; Kabir, M.; Crochet, A. P.; Francis, M.

2010-04-01

372

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

373

Comparison of amino acids interaction with gold nanoparticle.  

PubMed

The study of nanomaterial/biomolecule interface is an important emerging field in bionanoscience, and additionally in many biological processes such as hard-tissue growth and cell-surface adhesion. To have a deeper understanding of the amino acids/gold nanoparticle assemblies, the adsorption of these amino acids on the gold nanoparticles (GNPs) has been investigated via molecular dynamics simulation. In these simulations, all the constituent atoms of the nanoparticles were considered to be dynamic. The geometries of amino acids, when adsorbed on the nanoparticle, were studied and their flexibilities were compared with one another. The interaction of each of 20 amino acids was considered with 3 and 8nm gold GNPs. PMID:24378870

Ramezani, Fatemeh; Amanlou, Massoud; Rafii-Tabar, Hashem

2014-04-01

374

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

375

Pyrolysis Gas Chromatography of Amino Acids and Proteins.  

National Technical Information Service (NTIS)

Pyrolysis gas chromatography was performed to estimate quickly and simply the amino acid composition. Two types of columns were constructed for use in the experiment. Considering that the ratios of the peak areas of pyrolysis gas chromatography patterns o...

K. Anomata Y. Mashiko

1972-01-01

376

Effects of divalent amino acids on iron absorption  

SciTech Connect

Solutions of each of 10 amino acids or ascorbic acid were mixed with iron and orally administered to rats. Iron was absorbed to a statistically significantly greater extent when mixed with asparagine, glycine, serine, or ascorbic acid as compared with a control solution of iron. The largest effects were for asparagine and glycine, which also increased iron absorption to a significantly greater extent than did serine or ascorbic acid. No statistically significant increase in iron absorption occurred when any of the other amino acids was mixed with iron. The extent of iron absorption from each test solution, as measured by area under the concentration of iron-59 in the blood-time curve (r2 . 0.0002), and the initial rate of iron absorption for each test solution (r2 . 0.01) showed no correlation with the stability constant of the amino acid-iron complex.

Christensen, J.M.; Ghannam, M.; Ayres, J.W.

1984-09-01

377

Evolution of the amino acid code: Inferences from mitochondrial codes  

Microsoft Academic Search

Summary The amino acid code is usually presented as a table of 64 codons. Actually the code results from the action of tRNA molecules that carry amino acids to codons in mRNA by means of codon-anticodon pairing. The tRNA molecules are transcribed from genes that undergo evolution and the number of anticodons can therefore increase during evolution, but the number

Thomas H. Jukes

1983-01-01

378

Amino Acid Transport Systems in Biotechnologically Relevant Bacteria  

Microsoft Academic Search

Besides metabolic pathways and regulatory networks, transport reactions are also pivotal for understanding\\u000a amino acid metabolism and production in bacteria. Apart from substrate uptake, this refers to product (amino\\u000a acid) excretion as well as product re-uptake. Both the mechanistic (kinetic and energetic) as well as structural\\u000a properties of these transport systems are relevant for understanding their significance and for providing

Kay Marin; Reinhard Kr鄝er

379

Production of Amino Acids: Physiological and Genetic Approaches  

Microsoft Academic Search

Large scale fermentative production of l-amino acids is still an important goal of modern biotechnology. Very large amounts of l-glutamate and l-lysine, as well as significant quantities of l-threonine and l-phenylalanine and other amino acids for the application in food, feed, and for pharmaceutical purposes are currently produced by fermentation using mainly the two organisms Corynebacterium glutamicum and Escherichia coli.

Reinhard Kr鄝er

2005-01-01

380

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

381

Response of brain amino acid metabolism to ketosis  

Microsoft Academic Search

Our objective was to study brain amino acid metabolism in response to ketosis. The underlying hypothesis is that ketosis is associated with a fundamental change of brain amino acid handling and that this alteration is a factor in the anti-epileptic effect of the ketogenic diet. Specifically, we hypothesize that brain converts ketone bodies to acetyl-CoA and that this results in

Marc Yudkoff; Yevgeny Daikhin; Ilana Nissim; Oksana Horyn; Adam Lazarow; Bohdan Luhovyy; Suzanne Wehrli; Itzhak Nissim

2005-01-01

382

Inborn errors of amino acid metabolism in North India  

Microsoft Academic Search

We screened 2560 referred cases for inborn errors of amino acid metabolism by chemical tests and thin-layer chromatography of urine\\/plasma. In 62(2.4%) cases, eleven inherited Mendelian disorders of amino acids were identified. The four commonest disorders were homocystinuria, alcaptonuria, maple syrup urine disease and nonketotic hyperglycinaemia. Ornithinaemia was detected in two cases (0.08%), and phenylketonuria and cystinuria in two cases

Manjeet Kaur; Ganesh Prasad; Ishwar Chander Verma

1994-01-01

383

The infrared absorption of amino acid side chains  

Microsoft Academic Search

Amino acid side chains play fundamental roles in stabilising protein structures and in catalysing enzymatic reactions. These fields are increasingly investigated by infrared spectroscopy at the molecular level. To help the interpretation of the spectra, a review of the infrared absorption of amino acid side chains in H2O and 2H2O is given. The spectral region of 2600900cm?1 is covered.

Andreas Barth

2000-01-01

384

Transient optical absorption spectra in pulse irradiated solid amino acids  

Microsoft Academic Search

A preliminary pulse radiolytic study is reported on transient optical absorption spectra in solid amino acids. Spectra have been obtained by improved Cherenkov Light Self-absorption Method applied during 5.5 s pulses of 10 or 13 MeV linac electrons. Amino acids exhibit a very different type of behaviour: from lack of absorption signal (at the present sensitivity of the system) to

Z. P. Zag鏎ski; Z. Tomasi?ski

1990-01-01

385

A note on the amino acid composition of the turkey.  

PubMed

1. The amino acid composition of the whole body protein of 28- and 56-day-old turkeys is reported. 2. There were some differences between the two ages; these could largely be reconciled by considering the likely differences in the proportion of feather protein. 3. The results were compared with similar values for the chicken and goose; overall there is a striking similarity, both in absolute concentrations and relative proportions of amino acids. PMID:7104783

Fisher, C; Scougall, R K

1982-05-01

386

Amino acid sequence restriction in rabbit antibody light chains.  

PubMed

Light chains were obtained from IgG rabbit antibodies to the group-specific carbohydrates of groups A and C streptococci. An analysis of the amino acid alternatives which exist at the first three positions of the N-terminus in both light-chain preparations shows a marked restriction in amino acid sequence heterogeneity when compared with preimmune light chains. Both of these related, but immunologically distinct, antigenic determinants select the same uncommon subpopulation of rabbit light chains. PMID:5259770

Hood, L; Lackland, H; Eichman, K; Kindt, T J; Braun, D G; Krause, R M

1969-07-01

387

Amino Acid Sequence Restriction in Rabbit Antibody Light Chains  

Microsoft Academic Search

Light chains were obtained from IgG rabbit antibodies to the group-specific carbohydrates of groups A and C streptococci. An analysis of the amino acid alternatives which exist at the first three positions of the N-terminus in both light-chain preparations shows a marked restriction in amino acid sequence heterogeneity when compared with preimmune light chains. Both of these related, but immunologically

Leroy Hood; Henry Lackland; Klaus Eichman; Thomas J. Kindt; Dietmar G. Braun; Richard M. Krause

1969-01-01

388

Genetic code correlations - Amino acids and their anticodon nucleotides  

NASA Technical Reports Server (NTRS)

The data here show direct correlations between both the hydrophobicity and the hydrophilicity of the homocodonic amino acids and their anticodon nucleotides. While the differences between properties of uracil and cytosine derivatives are small, further data show that uracil has an affinity for charged species. Although these data suggest that molecular relationships between amino acids and anticodons were responsible for the origin of the code, it is not clear what the mechanism of the origin might have been.

Weber, A. L.; Lacey, J. C., Jr.

1978-01-01

389

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

390

Experimental methods for scanning unnatural amino acid mutagenesis  

PubMed Central

Summary Site-specific incorporation of unnatural amino acids into proteins in vivo relies on the genetic reassignment of nonsense or quadruplet codons. Here, we describe a general procedure for the random introduction of these codons into open reading frames resulting in protein libraries that are scanned with unnatural amino acid residues. These libraries can enable large-scale mutagenesis experiments aimed at understanding and improving protein function.

Liu, Jia; Cropp, T. Ashton

2014-01-01

391

Intracellular sensing of amino acids in Xenopus laevis oocytes stimulates p70 S6 kinase in a target of rapamycin-dependent manner.  

PubMed

Amino acids exert modulatory effects on proteins involved in control of mRNA translation in animal cells through the target of rapamycin (TOR) signaling pathway. Here we use oocytes of Xenopus laevis to investigate mechanisms by which amino acids are "sensed" in animal cells. Small ( approximately 48%) but physiologically relevant increases in intracellular but not extracellular total amino acid concentration (or Leu or Trp but not Ala, Glu, or Gln alone) resulted in increased phosphorylation of p70(S6K) and its substrate ribosomal protein S6. This response was inhibited by rapamycin, demonstrating that the effects require the TOR pathway. Alcohols of active amino acids substituted for amino acids with lower efficiency. Oocytes were refractory to changes in external amino acid concentration unless surface permeability of the cell to amino acids was increased by overexpression of the System L amino acid transporter. Amino acid-induced, rapamycin-sensitive activation of p70(S6K) was conferred when System L-expressing oocytes were incubated in extracellular amino acids, supporting intracellular localization of the putative amino acid sensor. In contrast to lower eukaryotes such as yeast, which possess an extracellular amino acid sensor, our findings provide the first direct evidence for an intracellular location for the putative amino acid sensor in animal cells that signals increased amino acid availability to TOR/p70(S6K). PMID:11788584

Christie, Graham R; Hajduch, Eric; Hundal, Harinder S; Proud, Christopher G; Taylor, Peter M

2002-03-22

392

Aspartate-Derived Amino Acid Biosynthesis in Arabidopsis thaliana  

PubMed Central

The aspartate-derived amino acid pathway in plants leads to the biosynthesis of lysine, methionine, threonine, and isoleucine. These four amino acids are essential in the diets of humans and other animals, but are present in growth-limiting quantities in some of the world's major food crops. Genetic and biochemical approaches have been used for the functional analysis of almost all Arabidopsis thaliana enzymes involved in aspartate-derived amino acid biosynthesis. The branch-point enzymes aspartate kinase, dihydrodipicolinate synthase, homoserine dehydrogenase, cystathionine gamma synthase, threonine synthase, and threonine deaminase contain well-studied sites for allosteric regulation by pathway products and other plant metabolites. In contrast, relatively little is known about the transcriptional regulation of amino acid biosynthesis and the mechanisms that are used to balance aspartate-derived amino acid biosynthesis with other plant metabolic needs. The aspartate-derived amino acid pathway provides excellent examples of basic research conducted with A. thaliana that has been used to improve the nutritional quality of crop plants, in particular to increase the accumulation of lysine in maize and methionine in potatoes.

Jander, Georg; Joshi, Vijay

2009-01-01

393

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

394

On the utility of alternative amino acid scripts  

PubMed Central

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.

Flower, Darren R

2012-01-01

395

Role of Ferrocyanides in the Prebiotic Synthesis of ?-Amino Acids  

NASA Astrophysics Data System (ADS)

We investigated the synthesis of ?-amino acids under possible prebiotic terrestrial conditions in the presence of dissolved iron (II) in a simulated prebiotic ocean. An aerosol-liquid cycle with a prebiotic atmosphere is shown to produce amino acids via Strecker synthesis with relatively high yields. However, in the presence of iron, the HCN was captured in the form of a ferrocyanide, partially inhibiting the formation of amino acids. We showed how HCN captured as Prussian Blue (or another complex compound) may, in turn, have served as the HCN source when exposed to UV radiation, allowing for the sustained production of amino acids in conjunction with the production of oxyhydroxides that precipitate as by-products. We conclude that ferrocyanides and related compounds may have played a significant role as intermediate products in the prebiotic formation of amino acids and oxyhydroxides, such as those that are found in iron-containing soils and that the aerosol cycle of the primitive ocean may have enhanced the yield of the amino acid production.

Ruiz-Bermejo, Marta; Osuna-Esteban, Susana; Zorzano, Mar燰-Paz

2013-06-01

396

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

397

Amino acids in carbonaceous meteorites: biotic or abiotic?  

NASA Astrophysics Data System (ADS)

Carbonaceous meteorites are relics of ancient parent bodies from the time of formation of our solar system, about 4.5 billion years ago. They contain many of the organic compounds (e.g. amino acids) that are considered the building blocks of life. Experiments that attempt to simulate the synthesis of amino acids from inorganic precursors results in racemates. However, we have observed that several of the common protein amino acids in carbonaceous meteorites are non-racemeic, exhibiting an L-enantiomer excess typical of life. Stable isotope analysis of the individual amino acid enantiomers confirms that this L-excess is extraterrestrial, rather than contamination subsequent to impact. It has generally been assumed that these amino acids were formed by abiotic processes and were initially racemic, with subsequent partial destruction of their respective D-enantiomers by abiotic processes. However, the alternative scenario, i.e. the L-excess being a relic of ancient life, is largely ignored. Here we address this possibility based on the distributions, stereochemistry and stable carbon and nitrogen isotope compositions of the amino acids in carbonaceous meteorites.

Engel, Michael H.; Andrus, Vlad E.; Macko, Stephen A.

2004-02-01

398

Release of Dissolved Amino Acids by Marine Zooplankton.  

PubMed

Marine net zooplankton release dissolved amino acids into the water. Release rates are positively correlated with temperature and can be estimated by the equation: Release rate, (milligrams of alpha-amino nitrogen per gram dry weight of zooplankton per day) = 1.0 x temperature ( degrees C) -5.9. Release rates appeared to be independent of the taxonomic composition of the test samples, which were variously dominated by copepods, salps, chaetognaths, coelenterates, or radiolarians. These amino acids constitute an important source of dissolved organic matter in the sea. PMID:17829748

Johannes, R E; Webb, K L

1965-10-01

399

Asymmetric synthesis of nonproteinogenic amino acids with l-amino acid transaminase: synthesis of (2 S)-2-amino-4-oxo-4-phenylbutyric and (3 E,2 S)-2-amino-4-phenylbutenoic acids  

Microsoft Academic Search

2,4-Dioxo-4-phenylbutyric acid and 2-oxo-4-phenylbut-3-enoic acid are converted to the corresponding (S)-2-amino acids by recombinant Escherichia coli whole cells over-expressing aromatic transaminase from Enterobacter sp. BK2K-1 (AroATEs) in high yields (6878%) and high enantiomeric purity (>99%) using l-aspartic acid as an amino donor.

Nitin W. Fadnavis; Su-Hyun Seo; Joo-Hyun Seo; Byung-Gee Kim

2006-01-01

400

An efficient preparation of N-methyl-alpha-amino acids from N-nosyl-alpha-amino acid phenacyl esters.  

PubMed

In this paper we describe a simple and efficient solution-phase synthesis of N-methyl-N-nosyl-alpha-amino acids and N-Fmoc-N-methyl-alpha-amino acids. This represents a very important application in peptide synthesis to obtain N-methylated peptides in both solution and solid phase. The developed methodology involves the use of N-nosyl-alpha-amino acids with the carboxyl function protected as a phenacyl ester and the methylating reagent diazomethane. An important aspect of this synthetic strategy is the possibility to selectively deprotect the carboxyl function or alternatively both amino and carboxyl moieties by using the same reagent with a different molar excess and under mild conditions. Furthermore, the adopted procedure keeps unchanged the acid-sensitive side chain protecting groups used in Fmoc-based synthetic strategies. PMID:20121053

Leggio, Antonella; Belsito, Emilia Lucia; De Marco, Rosaria; Liguori, Angelo; Perri, Francesca; Viscomi, Maria Caterina

2010-03-01

401

Expression in Lactococcus lactis of functional genes related to amino acid catabolism and cheese aroma formation is influenced by branched chain amino acids.  

PubMed

Formation of cheese aroma compounds by Lactococcus lactis from amino acid catabolism depends on a complex network of reactions, which involve enzymes such as aminotransferases, dehydrogenases, lyases, and decarboxylases, among others. Based on the ability of some L. lactis strains to grow with low requirements of amino acids, we have studied in L. lactis IFPL730 the effect of the branched chain amino acid (BCAA) content on the expression of functional genes related to amino acid catabolism and aroma compound formation (araT, bcaT, kivD, ytjE and panE). L. lactis IFPL730 growth rate decreased under leucine, valine or isoleucine starvation but the strain reached similar viable counts at the stationary phase in all culture conditions studied. The level of expression of some genes encoding enzymes involved in amino acid catabolism changed significantly (P<0.05) when those conditions were compared. Specially, ?-ketoisovalerate decarboxylase (kivD), BCAA-specific aminotransferase (bcaT) and C-S lyase (yjtE) gene expressions increased markedly by both isoleucine and valine starvation. In addition to gene expression, formation of volatile compounds was determined in all growth conditions. The results showed that BCAA starvation conditions caused a significant increase (P<0.05) in the formation of metabolic end products related to cheese aroma, such as 3-methylbutanal and 3-methylbutanol. PMID:23107499

Garc燰-Cayuela, Tom嫳; G鏔ez de Cadi鎙nos, Luz P; Pel墈z, Carmen; Requena, Teresa

2012-10-15

402

Amino Acid Content of Noncell and Cell Wall Fractions in Feedstuffs  

Microsoft Academic Search

Total and phosphate buffer insoluble amino acids were determined for corn grain and silage, dried brewer's grain, timothy hay, and soybean meal. In addition, amino acid compositions of the acid detergent residue and neutral deter- gent residue were determined, and soluble amino acids were estimated for each feedstuff. Variation of amino acid con- centrations among protein fractions as percent of

T. V. Muscato; C. J. Sniffen; U. Krishnamoorthy; P. J. Van Soest

1983-01-01

403

Distinct amino acid-sensing mTOR pathways regulate skeletal myogenesis  

PubMed Central

Signaling through the mammalian target of rapamycin (mTOR) in response to amino acid availability controls many cellular and developmental processes. mTOR is a master regulator of myogenic differentiation, but the pathways mediating amino acid signals in this process are not known. Here we examine the Rag GTPases and the class III phosphoinositide 3-kinase (PI3K) Vps34, two mediators of amino acid signals upstream of mTOR complex 1 (mTORC1) in cell growth regulation, for their potential involvement in myogenesis. We find that, although both Rag and Vps34 mediate amino acid activation of mTORC1 in C2C12 myoblasts, they have opposing functions in myogenic differentiation. Knockdown of RagA/B enhances, whereas overexpression of active RagB/C mutants impairs, differentiation, and this inhibitory function of Rag is mediated by mTORC1 suppression of the IRS1-PI3K-Akt pathway. On the other hand, Vps34 is required for myogenic differentiation. Amino acids activate a Vps34-phospholipase D1 (PLD1) pathway that controls the production of insulin-like growth factor II, an autocrine inducer of differentiation, through the Igf2 muscle enhancer. The product of PLD, phosphatidic acid, activates the enhancer in a rapamycin-sensitive but mTOR kinaseindependent manner. Our results uncover amino acidsensing mechanisms controlling the homeostasis of myogenesis and underline the versatility and context dependence of mTOR signaling.

Yoon, Mee-Sup; Chen, Jie

2013-01-01

404

Proton affinity of several basic non-standard amino acids  

NASA Astrophysics Data System (ADS)

The structures and absolute proton affinities of several arginine (2-amino-3-guanidinopropionic acid, 2-amino-4-guanidinobutyric acid, homoarginine, citrulline and canavanine), histidine (1-methylhistidine and 3-methylhistidine) and lysine (2,3-diaminopropanoic acid, 2,4-diaminobutanoic acid, ornithine, 5-hydroxylysine, canaline and thialysine) homologues and analogues have been estimated using composite G3MP2B3 computational protocol. For a majority of here studied non-standard amino acids the gas-phase proton affinities were established for the first time, while for the others obtained values are used to improve the accuracy of the computational and experimental proton affinities reported previously. In addition, structures and proton affinities are discussed in order to rationalize their biological activity.

Roman, Marko

2012-08-01

405

Effect of an Amino Acid Imbalance on the Metabolism of the Most-limiting Amino Acid in the Rat  

Microsoft Academic Search

Rats trained to consume their entire daily ration in 1.5 hours were used to study the effect of an amino acid imbalance on the uptake of the limiting amino acid into the protein and protein-free portions of a number of tissues. They were fed 7.5 g of one of the following 3 diets containing L-histidine-U-14C: a 6% casein basal diet

N. J. BENEVENGA; A. E. HARPER; ANDQ. R. ROGERS

406

Changes with aging in the levels of amino acids in rat CNS structural elements I. Glutamate and related amino acids  

Microsoft Academic Search

Glutamate and related amino acids were determined in 53 discrete brain areas of 3-and 29-month-old male Fischer 344 rats microdissected with the punch technique. The levels of amino acids showed high regional variation-the ratio of the highest to lowest level was 9 for aspartate, 5 for glutamate, 6 for glutamine, and 21 for GABA. Several areas were found to have

M. Banay-Schwartz; A. Lajtha; M. Palkovits

1989-01-01

407

Amino acid uptake in isolated chick embryo heart cells.  

PubMed

1. The preparation of cell suspensions by treatment of chick embryo hearts with collagenase at various stages of development is described. 2. Measurements of oxygen consumption, incorporation of labelled leucine into protein and accumulation of labelled alpha-aminoisobutyric acid against a concentration gradient indicated a long-lasting viability of the isolated heart cells in vitro; a satisfactory preservation of subcellular structures, including plasma membrane, was assessed by electron-microscopic examination. 3. The rate of alpha-aminoisobutyric acid accumulation by cardiac cells isolated from hearts at different stages of embryological development decreased with aging; insulin stimulated the intracellular accumulation of this amino acid analogue. 4. Insulin increased the uptake by isolated heart cells of several (14)C-labelled naturally occurring amino acids; however, the fraction of amino acid taken up by the cells that was recovered free intracellularly, and therefore the concentration ratio (between intracellular water and medium), was enhanced by the hormone only with glycine, proline, serine, threonine, histidine and methionine. When isolated heart cells were incubated in the presence of a mixture of labelled amino acids, the addition of insulin increased the disappearance of radioactivity from the medium. 5. The general pattern of amino acid transport (in the absence and in the presence of insulin) in isolated cardiac cells was similar to that found in intact hearts, suggesting that the biological preparation described in this paper might be useful for studies of cell permeability and insulin action. PMID:4309308

Guidotti, G G; Lneburg, B; Borghetti, A F

1969-08-01

408

Raman spectra of amino acids and their aqueous solutions  

NASA Astrophysics Data System (ADS)

Amino acids are the basic "building blocks" that combine to form proteins and play an important physiological role in all life-forms. Amino acids can be used as models for the examination of the importance of intermolecular bonding in life processes. Raman spectra serve to obtain information regarding molecular conformation, giving valuable insights into the topology of more complex molecules (peptides and proteins). In this paper, amino acids and their aqueous solution have been studied by Raman spectroscopy. Comparisons of certain values for these frequencies in amino acids and their aqueous solutions are given. Spectra of solids when compared to those of the solute in solution are invariably much more complex and almost always sharper. We present a collection of Raman spectra of 18 kinds of amino