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1

AMINO ACID REQUIREMENTS FOR MICROBIAL PROTEIN SYNTHESIS  

E-print Network

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

Paris-Sud XI, Université de

2

AMINO ACID REQUIREMENTS OF HERPES SIMPLEX VIRUS IN HUMAN CELLS.  

PubMed

Tankersley, Robert W., Jr. (Medical College of Virginia, Richmond). Amino acid requirements of herpes simplex virus in human cells. J. Bacteriol. 87:609-613. 1964.-Progressive infection of human cells minimally infected with herpes simplex virus requires 11 of the amino acids of Eagle's medium, and glutamine. Lysine is not required, but rather exerts a partially inhibitory effect upon virus multiplication. Infected cells deprived of arginine support neither cytopathogenic effects nor virus replication; when arginine is replaced, a prompt and extensive infection follows. The effect of nutritional deficiencies on virus infection is discussed. PMID:14127578

TANKERSLEY, R W

1964-03-01

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

The requirements of the brain for some amino acids.  

PubMed Central

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

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

1975-01-01

5

Studies on the amino acid requirements of horses  

E-print Network

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

Word, James Dewey

1968-01-01

6

Carbobenzoxy amino acids: Structural requirements for cholecystokinin receptor antagonist activity  

SciTech Connect

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

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

1985-04-01

7

A Model of Proto-Anti-Codon RNA Enzymes Requiring L-Amino Acid Homochirality  

E-print Network

A Model of Proto-Anti-Codon RNA Enzymes Requiring L-Amino Acid Homochirality Albert Erives Received natural amino acid units of polypeptides using a universal scheme of triplet nucleotide ``codons) the absence of any codons for D-amino acids; (ii) the odd combination of alternate codon patterns for some

Erives, Albert J.

8

Autophagy and amino acid homeostasis are required for chronological longevity in Saccharomyces cerevisiae  

E-print Network

Autophagy and amino acid homeostasis are required for chronological longevity in Saccharomyces). Autophagy is a degra- dative process responsible for amino acid recycling in response to nitrogen starvation and amino acid limitation. We have investigated the role of autophagy during chronological aging of yeast

Aris, John P.

9

Amino Acids  

NSDL National Science Digital Library

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

10

Estimated quantitative amino acid requirements for Florida pompano reared in low-salinity  

Technology Transfer Automated Retrieval System (TEKTRAN)

As with most marine carnivores, Florida pompano require relatively high crude protein diets to obtain optimal growth. Precision formulations to match the dietary indispensable amino acid (IAA) pattern to a species’ requirements can be used to lower the overall dietary protein. However IAA requirem...

11

Zwitterion formation in hydrated amino acid, dipole bound anions: How many water molecules are required?  

NASA Astrophysics Data System (ADS)

While the naturally occurring amino acids are not zwitterions in the vapor phase, they are in aqueous solutions, implying that water plays an important role in inducing zwitterion formation. Together, these observations inspire the question, "How many water molecules are required to induce zwitterion formation in a given amino acid molecule?" In this paper, we address this question in the context of mass spectrometric and size-selected photoelectron spectroscopic studies of hydrated amino acid anions. We utilize the facts that zwitterions possess very large dipole moments, and that excess electrons can bind to strong dipole fields to form dipole bound anions, which in turn display distinctive and recognizible photoelectron spectral signatures. The appearance of dipole-bound photoelectron spectra of hydrated amino acid anions, beginning at a given hydration number, thus signals the onset of greatly enhanced dipole moments there and, by implication, of zwitterion formation. We find that five water molecules are needed to transform glycine into its zwitterion, while four each are required for phenylalanine and tryptophan. Since the excess electron may also make a contribution to zwitterion stabilization, these numbers are lower limits for how many water molecules are needed to induce zwitterion formation in these amino acids when no extra (net) charges are involved.

Xu, Shoujun; Nilles, J. Michael; Bowen, Kit H.

2003-11-01

12

Models to Estimate Amino Acid Requirements for Broiler Chickens: A Review  

Microsoft Academic Search

Computerized growth models can be a useful tool to determine more profitable and accurate concentrations and balance of dietary amino acids and other nutrients for broiler chickens. The methodology of mathematical modeling can be rapidly accepted in poultry nutrition and research due to the complexity of nutrient requirement estimations in practical and economical terms, and the necessity to have some

E. O. Oviedo-Rondon

2002-01-01

13

Surgical stress resistance induced by single amino acid deprivation requires Gcn2 in mice.  

PubMed

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. PMID:22277968

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

2012-01-25

14

Plasma amino acids  

MedlinePLUS

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

15

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

Federal Register 2010, 2011, 2012, 2013, 2014

...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

16

Lysine requirements of pre-lay broiler breeder pullets: determination by indicator amino acid oxidation.  

PubMed

The indicator amino acid oxidation (IAAO) method allows the determination of amino acid requirements under conditions of low growth rate as found in pre-laying broiler breeder pullets. Cobb 500 breeder pullets (20 wk old; 2290 +/- 280 g, n = 4) were adapted (6 d) to a pelleted, purified control diet containing all nutrients at >or=110% of NRC recommendations. After recovery from surgery for implantation of a jugular catheter, each bird was fed, in random order, test diets containing one of nine levels of lysine (0.48, 0.96, 1.92, 2.88, 3.84, 4.80, 7.68, 9.60 and 14.40 g/kg of diet). Indicator oxidation was determined during 4-h primed (74 kBq/kg body), constant infusions (44 kBq x h(-1). kg body(-1)) of L-[1-(14)C]phenylalanine. Using the breakpoint of a one-slope broken-line model, the lysine requirement was determined to be 4.88 +/- 0.96 g/kg of diet or 366 +/- 72 mg x hen(-1) x d(-1) with an upper 95% CI of 6.40 g/kg of diet or 480 mg x hen(-1) x d(-1). IAAO allows determination of individual bird amino acid requirements for specific ages and types of birds over short periods of time and enables more accurate broiler breeder pullet diet formulation. PMID:12949372

Coleman, Russell A; Bertolo, Robert F; Moehn, Soenke; Leslie, Michael A; Ball, Ronald O; Korver, Doug R

2003-09-01

17

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

PubMed

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

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

2010-09-01

18

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

19

Simulating evolution by gene duplication of protein features that require multiple amino acid residues  

PubMed Central

Gene duplication is thought to be a major source of evolutionary innovation because it allows one copy of a gene to mutate and explore genetic space while the other copy continues to fulfill the original function. Models of the process often implicitly assume that a single mutation to the duplicated gene can confer a new selectable property. Yet some protein features, such as disulfide bonds or ligand binding sites, require the participation of two or more amino acid residues, which could require several mutations. Here we model the evolution of such protein features by what we consider to be the conceptually simplest route—point mutation in duplicated genes. We show that for very large population sizes N, where at steady state in the absence of selection the population would be expected to contain one or more duplicated alleles coding for the feature, the time to fixation in the population hovers near the inverse of the point mutation rate, and varies sluggishly with the ?th root of 1/N, where ? is the number of nucleotide positions that must be mutated to produce the feature. At smaller population sizes, the time to fixation varies linearly with 1/N and exceeds the inverse of the point mutation rate. We conclude that, in general, to be fixed in 108 generations, the production of novel protein features that require the participation of two or more amino acid residues simply by multiple point mutations in duplicated genes would entail population sizes of no less than 109. PMID:15340163

Behe, Michael J.; Snoke, David W.

2004-01-01

20

Novel Toxic Shock Syndrome Toxin-1 Amino Acids Required for Biological Activity  

PubMed Central

Superantigens interact with T lymphocytes and macrophages to cause T lymphocyte proliferation and overwhelming cytokine production, which lead to toxic shock syndrome. Staphylococcus aureus superantigen toxic shock syndrome toxin-1 is a major cause of menstrual toxic shock syndrome. In general, superantigen-secreting S. aureus remain localized at the vaginal surface, and the superantigen must therefore penetrate the vaginal mucosa to interact with underlying immune cells to cause toxic shock syndrome. A dodecapeptide region (toxic shock syndrome toxin-1 amino acids F119-D130), relatively conserved among superantigens, has been implicated in superantigen penetration of epithelium. The purpose of this study was to determine amino acids within this dodecapeptide region that are required for interaction with vaginal epithelium. Alanine mutations were constructed in S. aureus toxic shock syndrome toxin-1 amino acids D120 to D130. All mutants maintained superantigenicity, and selected mutants were lethal when given intravenously to rabbits. Toxic shock syndrome toxin-1 induces interleukin-8 from immortalized human vaginal epithelial cells; however three toxin mutants (S127A, T128A, and D130A) induced low levels of interleukin-8 compared to wild type toxin. When carboxy-terminal mutants (S127A to D130A) were administered vaginally to rabbits, D130A was nonlethal, while S127A and T128A demonstrated delayed lethality compared to wild type toxin. In a porcine ex vivo permeability model, mutant D130A penetrated vaginal mucosa more quickly than wild type toxin. Toxic shock syndrome toxin-1 residue D130 may contribute to binding an epithelial receptor, which allows it to penetrate vaginal mucosa, induce interleukin-8, and cause toxic shock syndrome. PMID:19012411

Brosnahan, Amanda J.; Schaefers, Matthew M.; Amundson, William H.; Mantz, Mary J.; Squier, Christopher A.; Peterson, Marnie L.

2009-01-01

21

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. PMID:9684881

Sun, J.; Sampson, N. S.

1998-01-01

22

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 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

2014-01-01

23

Distinct Amino Acid Compositional Requirements for Formation and Maintenance of the [PSI+] Prion in Yeast.  

PubMed

Multiple yeast prions have been identified that result from the structural conversion of proteins into a self-propagating amyloid form. Amyloid-based prion activity in yeast requires a series of discrete steps. First, the prion protein must form an amyloid nucleus that can recruit and structurally convert additional soluble proteins. Subsequently, maintenance of the prion during cell division requires fragmentation of these aggregates to create new heritable propagons. For the Saccharomyces cerevisiae prion protein Sup35, these different activities are encoded by different regions of the Sup35 prion domain. An N-terminal glutamine/asparagine-rich nucleation domain is required for nucleation and fiber growth, while an adjacent oligopeptide repeat domain is largely dispensable for prion nucleation and fiber growth but is required for chaperone-dependent prion maintenance. Although prion activity of glutamine/asparagine-rich proteins is predominantly determined by amino acid composition, the nucleation and oligopeptide repeat domains of Sup35 have distinct compositional requirements. Here, we quantitatively define these compositional requirements in vivo. We show that aromatic residues strongly promote both prion formation and chaperone-dependent prion maintenance. In contrast, nonaromatic hydrophobic residues strongly promote prion formation but inhibit prion propagation. These results provide insight into why some aggregation-prone proteins are unable to propagate as prions. PMID:25547291

MacLea, Kyle S; Paul, Kacy R; Ben-Musa, Zobaida; Waechter, Aubrey; Shattuck, Jenifer E; Gruca, Margaret; Ross, Eric D

2015-03-01

24

Kidney amino acid transport  

Microsoft Academic Search

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

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

2009-01-01

25

Essential amino acid transporter Lat4 (Slc43a2) is required for mouse development.  

PubMed

Amino acid uniporter Lat4 (Slc43a2) mediates facilitated diffusion of branched-chain amino acids, methionine and phenylalanine, but its physiological role and subcellular localization are not known. We report here that Slc43a2 knock-out mice were born at expected Mendelian frequency but displayed an ?10% intrauterine growth retardation and low amniotic fluid amino acids suggesting defective transplacental transport. Postnatal growth was strongly reduced with premature death occurring within 9 days such that further investigations were made within three days after birth. Lat4 immunofluorescence showed a strong basolateral signal in small intestine, kidney proximal tubule and thick ascending limb epithelial cells of wild type but not Slc43a2 null littermates and no signal in liver and skeletal muscle. Experiments using Xenopus laevis oocytes demonstrated that Lat4 functioned as symmetrical low affinity uniporter with a K0.5 of ?5 mM for both in- and efflux. Plasma amino acid concentration was decreased in Slc43a2 null pups, in particular that of non-essential amino acids alanine, serine, histidine and proline. Together with an increased level of plasma long chain acylcarnitines and a strong alteration of liver gene expression, this indicates malnutrition. Attempts to rescue pups by decreasing the litter size or by intraperitoneal nutrients injection did not succeed. Radioactively labeled leucine but not lysine given per os accumulated in small intestine of Slc43a2null pups suggesting defective transcellular transport of Lat4 substrates. Taken together, Lat4 is a symmetrical uniporter for neutral essential amino acids localizing at the basolateral side of (re)absorbing epithelia and is necessary for early nutrition and development. This article is protected by copyright. All rights reserved. PMID:25480797

Guetg, Adriano; Mariotta, Luca; Bock, Lukas; Herzog, Brigitte; Fingerhut, Ralph; Camargo, Simone M R; Verrey, François

2014-12-01

26

Amino Acid Crossword Puzzle  

ERIC Educational Resources Information Center

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

Sims, Paul A.

2011-01-01

27

The nutritional value of plant-based diets in relation to human amino acid and protein requirements.  

PubMed

The adequacy of plant-based diets in developed and developing countries as sources of protein and amino acids for human subjects of all ages is examined. Protein quantity is shown not to be an issue. Digestibility is identified as a problem for some cereals (millet (Panicum miliaceum) and sorghum (Sorghum sp.)) and generally is poorly understood. Direct measurements of biological value in children are reviewed and scoring is considered. Various existing requirement values for amino acids and especially lysine are reviewed, and it is concluded that stable-isotope studies do not yet provide adequate alternative values of N balance data, which for lysine are robust after recalculation and adjustment. A new maintenance requirement pattern is developed, with higher values than those of Food and Agriculture Organization/World Health Organization/United Nations University (1985) but lower values than the Massachusetts Institute of Technology pattern (Young et al. 1989). Calculations of age-related amino acid requirements are based on most recent estimates of human growth and maintenance protein requirements, a tissue amino acid pattern and the new maintenance amino acid pattern. These values appear valid when used to score plant proteins, since they indicate values similar to or less than the biological value measured directly in young children. When used to score plant-based diets in India, no marked deficiencies are identified. All regions score > 1 for adults, whilst for children scores range from > 1, (Tamil Nadhu) from 6 months of age to 0.78 (West Bengal), rising to 0.9 in the 2-5 year old, consistent with reports that high-lysine maize supports similar weight and height growth to that of casein. Inadequate amino acid supply is not an issue with most cereal-based diets. PMID:10466163

Millward, D J

1999-05-01

28

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

29

Amino Acid Sequences of Porcine Sp38 and Proacrosin Required for Binding to the Zona Pellucida  

Microsoft Academic Search

We previously purified a boar sperm protein, sp38, and demonstrated that this protein bound to the 90-kDa family of zona pellucida (ZP) glycoprotein in a calcium-dependent manner. Sp38 competed with proacrosin for the binding to the zona pellucida. Herein we have isolated cDNA clones encoding sp38 from a boar testis cDNA library in ?gt11. The amino acid sequence deduced from

Etsuko Mori; Shin-ichi Kashiwabara; Tadashi Baba; Yoshimasa Inagaki; Tsuneatsu Mori

1995-01-01

30

Amino Acid Homeostasis and Chronological Longevity in Saccharomyces cerevisiae  

E-print Network

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

Aris, John P.

31

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

PubMed Central

A novel coronavirus, severe acute respiratory syndrome coronavirus (SARS-CoV), has recently been identified 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 of the viral envelope with the host cell membrane. Here we describe the construction and expression of a soluble codon-optimized SARS-CoV S glycoprotein comprising the first 1,190 amino acids of the native S glycoprotein (S1190). The codon-optimized and native S glycoproteins exhibit similar molecular weight as determined by Western blot analysis, indicating that synthetic S glycoprotein is modified correctly in a mammalian expression system. S1190 binds to the surface of Vero E6 cells, a cell permissive to infection, as demonstrated by fluorescence-activated cell sorter analysis, suggesting that S1190 maintains the biologic activity present in native S glycoprotein. This interaction is blocked with serum obtained from recovering SARS patients, indicating that the binding is specific. In an effort to map the ligand-binding domain of the SARS-CoV S glycoprotein, carboxy- and amino-terminal truncations of the S1190 glycoprotein were constructed. Amino acids 270 to 510 were the minimal receptor-binding region of the SARS-CoV S glycoprotein as determined by flow cytometry. We speculate that amino acids 1 to 510 of the SARS-CoV S glycoprotein represent a unique domain containing the receptor-binding site (amino acids 270 to 510), analogous to the S1 subunit of other coronavirus S glycoproteins. PMID:15078936

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

2004-01-01

32

Brain amino acid sensing.  

PubMed

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

Tsurugizawa, T; Uneyama, H; Torii, K

2014-09-01

33

Novel renal amino acid transporters.  

PubMed

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

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

2005-01-01

34

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

E-print Network

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

Zare, Richard N.

35

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, 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 · 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 Jr, A

2012-10-01

36

A Stereodivergent Approach to Amino Acids, Amino Alcohols, or  

E-print Network

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

Spino, Claude

37

TOR signaling is required for amino acid stimulation of early trypsin protein synthesis in the midgut of Aedes aegypti mosquitoes.  

PubMed

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. PMID:18708143

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

2008-10-01

38

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. PMID:18708143

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

2008-01-01

39

The tuberous sclerosis protein TSC2 is not required for the regulation of the mammalian target of rapamycin by amino acids and certain cellular stresses.  

PubMed

Amino acids positively regulate signaling through the mammalian target of rapamycin (mTOR). Recent work demonstrated the importance of the tuberous sclerosis protein TSC2 for regulation of mTOR by insulin. TSC2 contains a GTPase-activator domain that promotes hydrolysis of GTP bound to Rheb, which positively regulates mTOR signaling. Some studies have suggested that TSC2 also mediates the control of mTOR by amino acids. In cells lacking TSC2, amino acid withdrawal still results in dephosphorylation of S6K1, ribosomal protein S6, the eukaryotic initiation factor 4E-binding protein, and elongation factor-2 kinase. The effects of amino acid withdrawal are diminished by inhibiting protein synthesis or adding back amino acids. These studies demonstrate that amino acid signaling to mTOR occurs independently of TSC2 and involves additional unidentified inputs. Although TSC2 is not required for amino acid control of mTOR, amino acid withdrawal does decrease the proportion of Rheb in the active GTP-bound state. Here we also show that Rheb and mTOR form stable complexes, which are not, however, disrupted by amino acid withdrawal. Mutants of Rheb that cannot bind GTP or GDP can interact with mTOR complexes. We also show that the effects of hydrogen peroxide and sorbitol, cell stresses that impair mTOR signaling, are independent of TSC2. Finally, we show that the ability of energy depletion (which impairs mTOR signaling in TSC2+/+ cells) to increase the phosphorylation of eukaryotic elongation factor 2 is also independent of TSC2. This likely involves the phosphorylation of the elongation factor-2 kinase by the AMP-activated protein kinase. PMID:15772076

Smith, Ewan M; Finn, Stephen G; Tee, Andrew R; Browne, Gareth J; Proud, Christopher G

2005-05-13

40

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

PubMed Central

Background The Nef protein of HIV facilitates virus replication and disease progression in infected patients. This role as pathogenesis factor depends on several genetically separable Nef functions that are mediated by interactions of highly conserved protein-protein interaction motifs with different host cell proteins. By studying the functionality of a series of nef alleles from clinical isolates, we identified a dysfunctional HIV group O Nef in which a highly conserved valine-glycine-phenylalanine (VGF) region, which links a preceding acidic cluster with the following proline-rich motif into an amphipathic surface was deleted. In this study, we aimed to study the functional importance of this VGF region. Results The dysfunctional HIV group O8 nef allele was restored to the consensus sequence, and mutants of canonical (NL4.3, NA-7, SF2) and non-canonical (B2 and C1422) HIV-1 group M nef alleles were generated in which the amino acids of the VGF region were changed into alanines (VGF?AAA) and tested for their capacity to interfere with surface receptor trafficking, signal transduction and enhancement of viral replication and infectivity. We found the VGF motif, and each individual amino acid of this motif, to be critical for downregulation of MHC-I and CXCR4. Moreover, Nef’s association with the cellular p21-activated kinase 2 (PAK2), the resulting deregulation of cofilin and inhibition of host cell actin remodeling, and targeting of Lck kinase to the trans-golgi-network (TGN) were affected as well. Of particular interest, VGF integrity was essential for Nef-mediated enhancement of HIV virion infectivity and HIV replication in peripheral blood lymphocytes. For targeting of Lck kinase to the TGN and viral infectivity, especially the phenylalanine of the triplet was essential. At the molecular level, the VGF motif was required for the physical interaction of the adjacent proline-rich motif with Hck. Conclusion Based on these findings, we propose that this highly conserved three amino acid VGF motif together with the acidic cluster and the proline-rich motif form a previously unrecognized amphipathic surface on Nef. This surface appears to be essential for the majority of Nef functions and thus represents a prime target for the pharmacological inhibition of Nef. PMID:22537596

2012-01-01

41

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. PMID:19703979

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

2009-01-01

42

BIOCHEMISTRY: The 22nd Amino Acid  

NSDL National Science Digital Library

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

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

2002-05-24

43

Growth requirements of hyperthermophilic sulfur-dependent heterotrophic archaea isolated from a shallow submarine geothermal system with reference to their essential amino acids.  

PubMed Central

Three hyperthermophilic sulfur-dependent heterotrophs were isolated from a shallow submarine hydrothermal system at an inlet of Kodakara-jima island, Kagoshima, Japan. The isolates grew at 60 to 97 degrees C, with the optimum temperatures at 85 to 90 degrees C. Sensitivity to rifampin and the existence of ether lipids indicated that the isolates are hyperthermophilic archaea. Partial sequencing of the genes coding for 16S rRNA showed that the three isolates are closely related to the genus Thermococcus. They grew on proteinaceous mixtures, such as yeast extract, Casamino Acids, and purified proteins (e.g., casein and gelatin), but not on carbohydrates or organic acids as sole carbon and energy sources. Nine amino acids were essential for growth of isolate KS-1 (Thr, Leu, Ile, Val, Met, Phe, His, Tyr, and Arg). Isolate KS-2 required Lys in addition to the nine amino acids, and KS-8 required Lys instead of Tyr. In comparative studies, it was shown that Thermococcus celer DSM 2476 required 10 amino acids (Thr, Leu, Ile, Val, Met, Phe, Tyr, Trp, Lys, and Arg) while Pyrococcus furiosus DSM 3638 required only Ile and Val. The hyperthermophilic fermentative eubacterium Thermotoga neapolitana DSM 4359 did not require any amino acids for growth. Images PMID:8085828

Hoaki, T; Nishijima, M; Kato, M; Adachi, K; Mizobuchi, S; Hanzawa, N; Maruyama, T

1994-01-01

44

An Abstracting Transformation for Amino Acid Polymorphism  

E-print Network

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

Texas at San Antonio, University of

45

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

46

Direct demonstration of critical amino acid residues required for cytotoxic T-lymphocyte allorecognition of H-2 class I antigens.  

PubMed Central

To identify critical amino acid residues recognized by alloreactive cytolytic T lymphocytes (CTL) generated between H-2Kb and H-2Kbm1, we have derived a series of cloned L-cell lines expressing the following mutant H-2Kb class I genes. Cell line L-KbTyr-Tyr expresses a mutant gene in which positions 155-156 of the Kb molecule have been changed from Arg-Leu to Tyr-Tyr, leaving position 152 unchanged. Cell line L-KbAla expresses the reciprocal mutant gene that has position 152 of the Kb molecule mutated from glutamic acid to alanine, leaving positions 155-156 unchanged. Electrophoretic mobilities of the mutant Kb molecules reflect only those changes predicted by the mutations. Mutant-specific (anti-Kbm1) and native-specific (anti-Kb) CTL lyse L-KbTyr-Tyr and L-KbAla target cells equally well. Unlabeled target inhibition of lysis revealed a pattern of recognition and inhibition that suggests that the amino acid differences between Kbm1 and Kb create at least two discrete determinants that can be recognized by different populations of CTL. The results suggest that these determinants consist, at least in part, of a linear amino acid sequence from which critical amino acid residues can be identified. Images PMID:2452442

McLaughlin-Taylor, E; Miyada, C G; McMillan, M; Wallace, R B

1988-01-01

47

Nutrient Requirements The Amino Acid Need for Milk Synthesis Is Defined by the Maximal Uptake  

E-print Network

requirement, i.e., the sum of maintenance need and milk synthesis need after adjustment for body weight loss (MG), 16 lactating sows were fed 1 of 4 isocaloric diets varying in protein concentrations (from 78 such as different rates of lactation performance and body weight change. In contrast, the factorial approach derives

Bequette, Brian J.

48

The Lysine and Total Sulfur Amino Acid Requirements of Six- to Twelve-kilogram Pigs  

Technology Transfer Automated Retrieval System (TEKTRAN)

Three experiments (Exp.) were conducted to determine the Lys and TSAA requirement of 6- to 12-kg pigs. There were five replications of five or six pigs per pen (n = 150, 150, and 168 with initial BW of 6.3, 6.7, and 6.4 kg and final BW of 10.8, 11.7, and 11.2 kg for Exp. 1, 2, and 3, respectively). ...

49

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

50

Fed levels of amino acids are required for the somatotropin-induced increase in muscle protein synthesis  

Technology Transfer Automated Retrieval System (TEKTRAN)

Chronic somatotropin (pST) treatment in pigs increases muscle protein synthesis and circulating insulin, a known promoter of protein synthesis. Previously, we showed that the pST-mediated rise in insulin could not account for the pST-induced increase in muscle protein synthesis when amino acids were...

51

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

52

Determination of the amino acid sequence requirements for catalysis by the highly proficient orotidine monophosphate decarboxylase  

PubMed Central

Orotidine 5?-monophosphate decarboxylase (ODCase) catalyzes the decarboxylation of orotidine 5?-monophosphate to uridine 5?-monophosphate during pyrimidine nucleotide biosynthesis. This enzyme is one of the most proficient known, exhibiting a rate enhancement of over 17 orders of magnitude over the uncatalyzed rate. An interesting question is whether the high proficiency of ODCase is associated with a highly optimized sequence of active site residues. This question was addressed by randomizing 24 residue positions in and around the active site of the E. coli ODCase (pyrF) by site-directed mutagenesis. The libraries of mutants were selected for function from a multicopy plasmid or by single-copy replacement at the pyrF locus on the E. coli chromosome. Stringent sequence requirements for function were found for the mutants expressed from the chromosomal pyrF locus. Six positions were not tolerant of substitutions and several others accepted very limited substitutions. In contrast, all positions could be substituted to some extent when the library mutants were expressed from a multicopy plasmid. For the conserved quartet of charged residues Lys44-Asp71-Lys73-Asp76, a cysteine substitution was found to provide function at positions 71 and 76. A lower pKa for both cysteine mutants supports a mechanism whereby the thiolate group of cysteine substitutes for the negatively charged aspartate side chain. The partial function mutants such as D71C and D76C exhibit reduced catalytic efficiency relative to wild type but nevertheless provide a rate enhancement of 15 orders of magnitude over the uncatalyzed rate indicating the catalytic proficiency of the enzyme is robust and tolerant of mutation. PMID:21898650

Yuan, Ji; Cardenas, Ana Maria; Gilbert, Hiram F; Palzkill, Timothy

2011-01-01

53

Cry1Aa binding to the cadherin receptor does not require conserved amino acid sequences in the domain II loops  

PubMed Central

Characterizing the binding mechanism of Bt (Bacillus thuringiensis) Cry toxin to the cadherin receptor is indispensable to understanding the specific insecticidal activity of this toxin. To this end, we constructed 30 loop mutants by randomly inserting four serial amino acids covering all four receptor binding loops (loops ?8, 1, 2 and 3) and analysed their binding affinities for Bombyx mori cadherin receptors via Biacore. High binding affinities were confirmed for all 30 mutants containing loop sequences that differed from those of wild-type. Insecticidal activities were confirmed in at least one mutant from loops 1, 2 and 3, suggesting that there is no critical amino acid sequence for the binding of the four loops to BtR175. When two mutations at different loops were integrated into one molecule, no reduction in binding affinity was observed compared with wild-type sequences. Based on these results, we discussed the binding mechanism of Cry toxin to cadherin protein. PMID:23145814

Fujii, Yuki; Tanaka, Shiho; Otsuki, Manami; Hoshino, Yasushi; Morimoto, Chinatsu; Kotani, Takuya; Harashima, Yuko; Endo, Haruka; Yoshizawa, Yasutaka; Sato, Ryoichi

2012-01-01

54

Amino acids and cell regulation.  

PubMed Central

Free amino play an important role in regulating cell volume in fishes. Four tissues/cells (skeletal muscle, RBC, brain, and myocardium) of the little skate, Raja erinacea, were selected for detailed study because of their special importance or unique advantage as experimental models. Three particular amino acids, beta-alanine, taurine, and sarcosine play a predominant role in all four tissues. As in higher vertebrates, amino acid uptake in skate brain, heart, and RBC is mediated via a Na+-dependent process. Amino acids leave the skate brain rapidly in response to a sudden decrease in plasma osmolality and/or to a simultaneous drop in extracellular Na+ concentration. However, although amino acids are important for volume regulation in normal brain cells, they do not appear to be likely candidates for the unidentified "idiogenic" osmolytes in mammalian brain cells. The high concentration of taurine in skate myocardium is of special interest because of the special role of this amino acid in myocardial contractility. Thus, unlike beta-alanine and sarcosine, taurine may play a dual role in regulating both cell volume and contractility of myocardial cells. The isolated skate atrium is well suited for in vitro studies of these two processes. PMID:395764

Forster, R. P.; Goldstein, L.

1979-01-01

55

The Cpc1 regulator of the cross-pathway control of amino acid biosynthesis is required for pathogenicity of the vascular pathogen Verticillium longisporum.  

PubMed

The plant-pathogenic fungus Verticillium longisporum is a causal agent of early senescence and ripening in cruciferous crops like Brassica napus. Verticillium wilts have become serious agricultural threats in recent decades. Verticillium species infect host plants through the roots and colonize xylem vessels of the host plant. The xylem fluid provides an environment with limited carbon sources and unbalanced amino acid supply, which requires V. longisporum to induce the cross-pathway control of amino acid biosynthesis. RNA-mediated gene silencing reduced the expression of the two CPC1 isogenes (VlCPC1-1 and VlCPC1-2) of the allodiploid V. longisporum up to 85%. VlCPC1 encodes the conserved transcription factor of the cross-pathway control. The silenced mutants were highly sensitive to amino-acid starvation, and the infected plants showed significantly fewer symptoms such as stunting or early senescence in oilseed rape plant infection assays. Consistently, deletion of single CPC1 of the haploid V. dahliae resulted in strains that are sensitive to amino-acid starvation and cause strongly reduced symptoms in the plant-host tomato (Solanum lycopersicum). The allodiploid V. longisporum and the haploid V. dahliae are the first phytopathogenic fungi that were shown to require CPC1 for infection and colonization of their respective host plants, oilseed rape and tomato. PMID:23883358

Timpner, Christian; Braus-Stromeyer, Susanna A; Tran, Van Tuan; Braus, Gerhard H

2013-11-01

56

Chemotaxis Toward Amino Acids in Escherichia coli  

PubMed Central

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

Mesibov, Robert; Adler, Julius

1972-01-01

57

Transport of amino acids in the kidney.  

PubMed

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

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

2014-01-01

58

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

59

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

60

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

E-print Network

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

Boyer, Edmond

61

The standard amino acids alanine ala A  

E-print Network

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

Guevara-Vasquez, Fernando

62

Combinatorics of aliphatic amino acids  

NASA Astrophysics Data System (ADS)

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

Grützmann, Konrad; Böcker, Sebastian; Schuster, Stefan

2011-01-01

63

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. PMID:23269789

Rodriguez, Kenny R.

2013-01-01

64

Nonprotein Amino Acids in the Murchison Meteorite  

PubMed Central

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

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

1971-01-01

65

Evolutionary Systems Biology of Amino Acid Biosynthetic Cost in Yeast  

PubMed Central

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

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

2010-01-01

66

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

Code of Federal Regulations, 2011 CFR

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

2011-07-01

67

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

68

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

69

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

Code of Federal Regulations, 2014 CFR

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

2014-07-01

70

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

Code of Federal Regulations, 2012 CFR

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

2012-07-01

71

Roast effects on coffee amino acid enantiomers  

Microsoft Academic Search

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

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

2005-01-01

72

Evolutionarily Conserved Optimization of Amino Acid Biosynthesis  

E-print Network

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

de Bivort, Benjamin

73

Intestinal metabolism of sulfur amino acids  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

74

Amino acids in earthworms: Are earthworms ecosystemivorous?  

Microsoft Academic Search

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

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

1997-01-01

75

21 CFR 172.320 - Amino acids.  

Code of Federal Regulations, 2014 CFR

... 2014-04-01 2014-04-01 false Amino acids. 172.320 Section 172.320 Food and...Dietary and Nutritional Additives § 172.320 Amino acids. The food additive amino acids may be safely used as nutrients added to...

2014-04-01

76

21 CFR 172.320 - Amino acids.  

Code of Federal Regulations, 2013 CFR

... 2013-04-01 2013-04-01 false Amino acids. 172.320 Section 172.320 Food and...Dietary and Nutritional Additives § 172.320 Amino acids. The food additive amino acids may be safely used as nutrients added to...

2013-04-01

77

Amino acid analyses of Apollo 14 samples.  

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

78

Unnatural reactive amino acid genetic code additions  

SciTech Connect

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

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

2014-08-26

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-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

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, 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

81

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

82

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

E-print Network

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

Paris-Sud XI, Université de

83

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

84

Amino Acid Properties Conserved in Molecular Evolution  

PubMed Central

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

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

2014-01-01

85

Amino acid contents of infant foods.  

PubMed

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

Bosch, Lourdes; Alegría, Amparo; Farré, Rosaura

2006-01-01

86

Identification of Amino Acid Residues of the Pheromone-binding Domain of the Transcription Factor TraR that are Required for Positive Control  

PubMed Central

Genes required for replication and for conjugal transfer of the Agrobacterium tumefaciens Ti plasmid are regulated by the quorum sensing transcription factor TraR, whose N-terminal domain binds to the pheromone N-3-oxooctanoyl-L-homoserine lactone (OOHL) and whose C-terminal domain binds to specific DNA sequences called tra boxes. Here, we constructed 117 mutants, altering 103 surface-exposed amino acid residues of the TraR N-terminal domain. Each mutant was tested for activation of the traI promoter, where TraR binds to a site centered 45 nucleotides upstream of the transcription start site, and of the traM promoter, where TraR binds a site centered 66 nucleotides upstream. Alteration of 18 residues blocked activity at the traI promoter. Of these, alteration at three positions impaired TraR abundance or DNA binding, leaving 15 residues that are specifically needed for positive control. Of these 15 residues, nine also blocked or reduced activity at the traM promoter, while six had no effect. Amino acid residues required for activation of both promoters probably contact the carboxy terminal domain of the RNA polymerase ? subunit, while residues required only for traI promoter activation may contact another RNA polymerase component. PMID:19602141

Costa, Esther D.; Cho, Hongbaek; Winans, Stephen C.

2009-01-01

87

Original article Effects of amino acids on the growth of an anaerobic  

E-print Network

Original article Effects of amino acids on the growth of an anaerobic rumen fungus Neocallimastix (Received 2 January 1996; accepted 25 March 1996) Summary ― The amino acid requirements amino acids (10 EAA) or eight nonessen- tial amino acids (8 NEAA), or both (18 AA). Although the fungus

Boyer, Edmond

88

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

89

N-Benzoyl-L-tyrosyl-p-aminobenzoic acid hydrolase beta (human meprinbeta). A 13-amino-acid sequence is required for proteolyticprocessing and subsequent secretion.  

PubMed

N-Benzoyl-L-tyrosyl-p-aminobenzoic acid hydrolase or human meprin (PPH) is a brush-border membrane enzyme of small intestinal epithelial cells. It is a type I integral membrane protein composed of two disulphide-bridged subunits (alpha and beta). PPH and its homologous counterparts in rodents belong to the astacin family of zinc-metalloendopeptidases. Although the amino-acid sequence of the beta subunits is 80-90% identical in these three species, processing is different. Expression of PPHbeta in simian virus 40-transformed African green monkey kidney cells (COS-1) and Madin Darby canine kidney (MDCK) cells results in its cell surface localization and secretion, whereas mouse meprinbeta is only found at the plasma membrane. To investigate proteolytic processing of PPHbeta and to identify the cleavage site, different C-terminal domains of wild-type PPHbeta were exchanged with the homologous domains of mouse meprinbeta. We identified a 13-amino-acid sequence (QIQLTPAPSVQDL) necessary for cleavage and subsequent secretion of PPHbeta. Using brefeldin A, the site of processing was identified as being after passage through the Golgi compartment. Proteolytic processing of PPHbeta thus provides a means for secretion of alphabeta heterodimers. PMID:10215852

Pischitzis, A; Hahn, D; Leuenberger, B; Sterchi, E E

1999-04-01

90

Characterization of Amino Acid Efflux from Isolated Soybean Cells 1  

PubMed Central

Cells from reproductive soybean (Glycine max [L.] Merr.) plants were isolated using a mechanical-enzymic technique that produced a high yield of uniform, physiologically active cells. Cells were incubated in a pH 6.0 buffered solution and subjected to various treatments in order to determine the nature of net amino acid efflux. Total net amino acid (ninhydrinreactive substances) efflux was not affected by the following conditions: (a) darkness, (b) aeration, (c) K+ concentrations of 0.1, 1.0, 10, or 100 millimolar and (d) pH 4, 5, 6, 7, or 8. The Q10 for net amino acid efflux between 10°C and 30°C was 1.6. Thus, it seems that net amino acid efflux requires neither current photosynthetic energy nor a pH/ion concentration gradient. Amino acid analyses of the intra-and extracellular fractions over time showed that each amino acid was exported linearly for at least 210 minutes, but that export rate was not necessarily related to internal amino acid pools. Amino acids that were exported fastest were alanine, lysine, leucine, and glycine. Addition of the inhibitor p-chloromercuriphenyl sulfonic acid, 3(3,4-dichlorophenyl)-1,1-dimethylurea, or carbonylcyanide p-trifluoromethoxyphenylhydrazone increased the rate of total amino acid efflux but had specific effects on the efflux of certain amino acids. For example, p-chloromercuriphenyl sulfonic acid greatly enhanced efflux of ?-aminobutyric acid, which is not normally exported rapidly even though a high concentration normally exists within cells. The data suggest that net amino acid efflux is a selective diffusional process. Because net efflux is the result of simultaneous efflux and influx, we propose that efflux is a facilitated diffusion process whereas influx involves energy-dependent carrier proteins. PMID:16663380

Secor, Jacob; Schrader, Larry E.

1984-01-01

91

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 GDU1’s 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. PMID:22291198

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

2012-01-01

92

Amino acid regulation of TOR complex 1.  

PubMed

TOR complex 1 (TORC1), an oligomer of the mTOR (mammalian target of rapamycin) protein kinase, its substrate binding subunit raptor, and the polypeptide Lst8/GbetaL, controls cell growth in all eukaryotes in response to nutrient availability and in metazoans to insulin and growth factors, energy status, and stress conditions. This review focuses on the biochemical mechanisms that regulate mTORC1 kinase activity, with special emphasis on mTORC1 regulation by amino acids. The dominant positive regulator of mTORC1 is the GTP-charged form of the ras-like GTPase Rheb. Insulin, growth factors, and a variety of cellular stressors regulate mTORC1 by controlling Rheb GTP charging through modulating the activity of the tuberous sclerosis complex, the Rheb GTPase activating protein. In contrast, amino acids, especially leucine, regulate mTORC1 by controlling the ability of Rheb-GTP to activate mTORC1. Rheb binds directly to mTOR, an interaction that appears to be essential for mTORC1 activation. In addition, Rheb-GTP stimulates phospholipase D1 to generate phosphatidic acid, a positive effector of mTORC1 activation, and binds to the mTOR inhibitor FKBP38, to displace it from mTOR. The contribution of Rheb's regulation of PL-D1 and FKBP38 to mTORC1 activation, relative to Rheb's direct binding to mTOR, remains to be fully defined. The rag GTPases, functioning as obligatory heterodimers, are also required for amino acid regulation of mTORC1. As with amino acid deficiency, however, the inhibitory effect of rag depletion on mTORC1 can be overcome by Rheb overexpression, whereas Rheb depletion obviates rag's ability to activate mTORC1. The rag heterodimer interacts directly with mTORC1 and may direct mTORC1 to the Rheb-containing vesicular compartment in response to amino acid sufficiency, enabling Rheb-GTP activation of mTORC1. The type III phosphatidylinositol kinase also participates in amino acid-dependent mTORC1 activation, although the site of action of its product, 3'OH-phosphatidylinositol, in this process is unclear. PMID:18765678

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

2009-04-01

93

Amino acid regulation of TOR complex 1  

PubMed Central

TOR complex 1 (TORC1), an oligomer of the mTOR (mammalian target of rapamycin) protein kinase, its substrate binding subunit raptor, and the polypeptide Lst8/G?L, controls cell growth in all eukaryotes in response to nutrient availability and in metazoans to insulin and growth factors, energy status, and stress conditions. This review focuses on the biochemical mechanisms that regulate mTORC1 kinase activity, with special emphasis on mTORC1 regulation by amino acids. The dominant positive regulator of mTORC1 is the GTP-charged form of the ras-like GTPase Rheb. Insulin, growth factors, and a variety of cellular stressors regulate mTORC1 by controlling Rheb GTP charging through modulating the activity of the tuberous sclerosis complex, the Rheb GTPase activating protein. In contrast, amino acids, especially leucine, regulate mTORC1 by controlling the ability of Rheb-GTP to activate mTORC1. Rheb binds directly to mTOR, an interaction that appears to be essential for mTORC1 activation. In addition, Rheb-GTP stimulates phospholipase D1 to generate phosphatidic acid, a positive effector of mTORC1 activation, and binds to the mTOR inhibitor FKBP38, to displace it from mTOR. The contribution of Rheb's regulation of PL-D1 and FKBP38 to mTORC1 activation, relative to Rheb's direct binding to mTOR, remains to be fully defined. The rag GTPases, functioning as obligatory heterodimers, are also required for amino acid regulation of mTORC1. As with amino acid deficiency, however, the inhibitory effect of rag depletion on mTORC1 can be overcome by Rheb overexpression, whereas Rheb depletion obviates rag's ability to activate mTORC1. The rag heterodimer interacts directly with mTORC1 and may direct mTORC1 to the Rheb-containing vesicular compartment in response to amino acid sufficiency, enabling Rheb-GTP activation of mTORC1. The type III phosphatidylinositol kinase also participates in amino acid-dependent mTORC1 activation, although the site of action of its product, 3?OH-phosphatidylinositol, in this process is unclear. PMID:18765678

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

2009-01-01

94

Enantiomeric excesses in meteoritic amino acids  

NASA Technical Reports Server (NTRS)

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

Cronin, J. R.; Pizzarello, S.

1997-01-01

95

Indigenous amino acids in primitive CR meteorites  

E-print Network

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

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

2008-03-10

96

Semantic Publishing of Knowledge about Amino Acids  

E-print Network

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

Robert Stevens; Phillip Lord

97

Indigenous amino acids in primitive CR meteorites  

E-print Network

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

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

2008-01-01

98

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

99

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

100

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

PubMed

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

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

2015-02-25

101

METABOLISM OF ?-AMINO ACIDS V.  

PubMed Central

Hardman, John K. (National Heart Institute, National Institutes of Health, Bethesda, Md.) and Thressa C. Stadtman. Metabolism of ?-amino acids. V. Energetics of the ?-aminobutyrate fermentation by Clostridium aminobutyricum. J. Bacteriol. 85:1326–1333. 1963.—Clostridium aminobutyricum utilizes ?-aminobutyrate as its sole carbon, nitrogen, and energy source, producing ammonia, acetate, and butyrate as a result of this fermentation. Coenzyme A (CoA)-transferase, phosphotransacetylase, and acetokinase activities have been demonstrated in crude extracts of the organism; the coupling of the reactions catalyzed by these enzymes to the fermentation reactions provides a mechanism whereby C. aminobutyricum can obtain energy, in the form of adenosine triphosphate, from the decomposition of ?-aminobutyrate. Indirect evidence of additional phosphorylation, at the electron-transport level, has been obtained from molar growth yield studies and from the inhibition by 2,4-dinitrophenol of butyrate synthesis from ?-aminobutyrate and from crotonyl-CoA. PMID:14047225

Hardman, John K.; Stadtman, Thressa C.

1963-01-01

102

Supernovae, Neutrinos and the Chirality of Amino Acids  

PubMed Central

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

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

2011-01-01

103

Supernovae, neutrinos and the chirality of amino acids.  

PubMed

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

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

2011-01-01

104

Amino Acid Uptake in Arbuscular Mycorrhizal Plants  

PubMed Central

We examined the extent to which arbuscular mycorrhizal (AM) fungi root improved the acquisition of simple organic nitrogen (ON) compounds by their host plants. In a greenhouse-based study, we used quantum dots (fluorescent nanoparticles) to assess uptake of each of the 20 proteinaceous amino acids by AM-colonized versus uncolonized plants. We found that AM colonization increased uptake of phenylalanine, lysine, asparagine, arginine, histidine, methionine, tryptophan, and cysteine; and reduced uptake of aspartic acid. Arbuscular mycorrhizal colonization had the greatest effect on uptake of amino acids that are relatively rare in proteins. In addition, AM fungi facilitated uptake of neutral and positively-charged amino acids more than negatively-charged amino acids. Overall, the AM fungi used in this study appeared to improve access by plants to a number of amino acids, but not necessarily those that are common or negatively-charged. PMID:23094070

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

2012-01-01

105

Research for amino acids in lunar samples.  

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

106

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

PubMed Central

Urinary amino acid analysis is typically done by cation-exchange chromatography followed by post-column derivatization with ninhydrin and UV detection. This method lacks throughput and specificity. Two recently introduced stable isotope ratio mass spectrometric methods promise to overcome those shortcomings. Using two blinded sets of urine replicates and a certified amino acid standard, we compared the precision and accuracy of gas chromatography/mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) of propyl chloroformate and iTRAQ® derivatized amino acids, respectively, to conventional amino acid analysis. The GC-MS method builds on the direct derivatization of amino acids in diluted urine with propyl chloroformate, GC separation and mass spectrometric quantification of derivatives using stable isotope labeled standards. The LC-MS/MS method requires prior urinary protein precipitation followed by labeling of urinary and standard amino acids with iTRAQ® tags containing different cleavable reporter ions distinguishable by MS/MS fragmentation. Means and standard deviations of percent technical error (%TE) computed for 20 amino acids determined by amino acid analyzer, GC-MS, and iTRAQ®-LC-MS/MS analyses of 33 duplicate and triplicate urine specimens were 7.27±5.22, 21.18±10.94, and 18.34±14.67, respectively. Corresponding values for 13 amino acids determined in a second batch of 144 urine specimens measured in duplicate or triplicate were 8.39±5.35, 6.23±3.84, and 35.37±29.42. Both GC-MS and iTRAQ®-LC-MS/MS are suited for high-throughput amino acid analysis, with the former offering at present higher reproducibility and completely automated sample pretreatment, while the latter covers more amino acids and related amines. PMID:19481989

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

2009-01-01

107

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

108

Amino acid regulation of gene expression.  

PubMed Central

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

Fafournoux, P; Bruhat, A; Jousse, C

2000-01-01

109

Acute regulation of mouse AE2 anion exchanger requires isoform-specific amino acid residues from most of the transmembrane domain  

PubMed Central

The widely expressed anion exchanger polypeptide AE2/SLC4A2 is acutely inhibited by acidic intracellular (pHi), by acidic extracellular pH (pHo), and by the calmodulin inhibitor, calmidazolium, whereas it is acutely activated by NH4+. The homologous erythroid/kidney AE1/SLC4A1 polypeptide is insensitive to these regulators. Each of these AE2 regulatory responses requires the presence of AE2's C-terminal transmembrane domain (TMD). We have now measured 36Cl? efflux from Xenopus oocytes expressing bi- or tripartite AE2–AE1 chimeras to define TMD subregions in which AE2-specific sequences contribute to acute regulation. The chimeric AE polypeptides were all functional at pHo 7.4, with the sole exception of AE2(1-920)/AE1(613-811)/AE2(1120-1237). Reciprocal exchanges of the large third extracellular loops were without effect. AE2 regulation by pHi, pHo and NH4+ was retained after substitution of C-terminal AE2 amino acids 1120–1237 (including the putative second re-entrant loop, two TM spans and the cytoplasmic tail) with the corresponding AE1 sequence. In contrast, the presence of this AE2 C-terminal sequence was both necessary and sufficient for inhibition by calmidazolium. All other tested TMD substitutions abolished AE2 pHi sensitivity, abolished or severely attenuated sensitivity to pHo and removed sensitivity to NH4+. Loss of AE2 pHi sensitivity was not rescued by co-expression of a complementary AE2 sequence within separate full-length chimeras or AE2 subdomains. Thus, normal regulation of AE2 by pH and other ligands requires AE2-specific sequence from most regions of the AE2 TMD, with the exceptions of the third extracellular loop and a short C-terminal sequence. We conclude that the individual TMD amino acid residues previously identified as influencing acute regulation of AE2 exert that influence within a regulatory structure requiring essential contributions from multiple regions of the AE2 TMD. PMID:17690150

Stewart, A K; Kurschat, C E; Vaughan-Jones, R D; Shmukler, B E; Alper, S L

2007-01-01

110

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

111

Inhibitors of Aromatic Amino Acid Biosynthesis  

NSDL National Science Digital Library

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

112

6th Amino Acid Assessment Workshop  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

113

Amino acid and albumin losses during hemodialysis  

Microsoft Academic Search

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

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

1994-01-01

114

Soil Bacteria Take Up D-Amino Acids, Protect Plants  

NASA Astrophysics Data System (ADS)

Recently, many groups reported D-amino acid uptake by plant roots, raising the question of whether soil D-amino acids represent a source of nitrogen or a source of toxicity. The discussion needs to be placed in the context of competition with rhizosphere bacteria. To provide this context, we followed the concentrations of D- and L-enantiomers of alanine, glutamic acid, aspartic acid, and leucine after they were added to soils in the laboratory. In all cases, the uptake of L-enantiomer began immediately and proceeded rapidly until exhausted. In contrast, the uptake of D-enantiomer required induction: an initial period of inactivity followed by rapid consumption comparable in rate to L-enantiomer. The induced nature of the D activity was confirmed by the addition of rifampicin, an mRNA synthesis inhibitor. Preventing the synthesis of new enzymes abolished soil flora's ability to consume D-amino acids, but not L-amino acids. These results suggest that inducible special racemase enzymes, which can convert D-amino acids back to their native L-forms, are widespread among soil microorganisms. This finding does not rule out the possibility that some plants may out-compete microorganisms and be able to access D-amino acids. It does suggest, however, that rhizosphere bacteria can shield plants from the toxic effect of D-amino acids.

Sun, H. J.; Zhang, G.

2011-12-01

115

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

PubMed Central

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

Cline, Martin J.; Lehrer, Robert I.

1969-01-01

116

Enzymatic aminoacylation of tRNA with unnatural amino acids  

E-print Network

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

Heller, Eric

117

Exogenous amino acids as fuel in shock.  

PubMed

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

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

1982-01-01

118

Preparation of some amino phosphonic acids  

E-print Network

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

Chambers, James Richard

1958-01-01

119

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

PubMed Central

Amino acid availability regulates cellular physiology by modulating gene expression and signal transduction pathways. However, although the signalling intermediates between nutrient availability and altered gene expression have become increasingly well documented, how eukaryotic cells sense the presence of either a nutritionally rich or deprived medium is still uncertain. From recent studies it appears that the intracellular amino acid pool size is particularly important in regulating translational effectors, thus, regulated transport of amino acids across the plasma membrane represents a means by which the cellular response to amino acids could be controlled. Furthermore, evidence from studies with transportable amino acid analogues has demonstrated that flux through amino acid transporters may act as an initiator of nutritional signalling. This evidence, coupled with the substrate selectivity and sensitivity to nutrient availability classically associated with amino acid transporters, plus the recent discovery of transporter-associated signalling proteins, demonstrates a potential role for nutrient transporters as initiators of cellular nutrient signalling. Here, we review the evidence supporting the idea that distinct amino acid "receptors" function to detect and transmit certain nutrient stimuli in higher eukaryotes. In particular, we focus on the role that amino acid transporters may play in the sensing of amino acid levels, both directly as initiators of nutrient signalling and indirectly as regulators of external amino acid access to intracellular receptor/signalling mechanisms. PMID:12879880

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

2003-01-01

120

Aromatic L-amino acid decarboxylase: conformational change in the flexible region around Arg334 is required during the transaldimination process.  

PubMed Central

Aromatic L-amino acid decarboxylase (AADC) catalytic mechanism has been proposed to proceed through two consecutive intermediates (i.e., Michaelis complex and the external aldimine). Limited proteolysis of AADC that preferentially digested at the C-terminal side of Arg334 was slightly retarded in the presence of dihydroxyphenyl acetate that formed a stable Michaelis complex. On the contrary, AADC was scarcely digested in the presence of L-dopa methyl ester that formed a stable external aldimine. Similar protection by the substrate analogs was observed in the chemical modification experiment. From these results, we concluded that the region around Arg334 must be exposed and flexible in the unliganded state, and forming the Michaelis complex generated a subtle conformational change, then underwent marked conformational change during the subsequent transaldimination process prerequisite to forming the external aldimine. For further analyses, we constructed a mutant gene encoding in tandem the two peptides of AADC cleaved at the Asn327-Met328 bond inside the putative flexible region. The gene product, fragmentary AADC, was still active with L-dopa as substrate, but its k(cat) value was decreased 57-fold, and the Km value was increased 9-fold compared with those of the wild-type AADC. The absorption spectra of the fragmentary AADC in the presence of L-dopa methyl ester showed shift in the equilibrium of the transaldimination from the external aldimine to the Michaelis complex. Tryptic digestion of the fragmentary AADC removed seven amino acid residues, Met328-Arg334, and resulted in complete inactivation. Susceptibility of the fragmentary enzyme to trypsin was not changed by L-dopa methyl ester revealing the loss of appropriate conformational change in the flexible region induced by substrate binding. From these results we propose that the conformational change in the flexible region is required during the transaldimination process. PMID:10082378

Ishii, S.; Hayashi, H.; Okamoto, A.; Kagamiyama, H.

1998-01-01

121

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

122

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

123

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

124

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

125

Effects of branched-chain amino acids on protein turnover.  

PubMed

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

May, M E; Buse, M G

1989-05-01

126

Enantiomer-specific selection of amino acids.  

PubMed

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

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

2013-12-01

127

Distribution of Amino Acids in Lunar Regolith  

NASA Technical Reports Server (NTRS)

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

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

2014-01-01

128

Amino Acid Metabolism Conflicts with Protein Diversity  

PubMed Central

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

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

2014-01-01

129

Quantitative analysis of amino acid mixtures by mass spectrometry  

E-print Network

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

Bird, James Spencer

1971-01-01

130

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

131

Protein, amino acids and the control of food intake.  

PubMed

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

Tome, Daniel

2004-08-01

132

Highly Efficient Asymmetric Synthesis of -Amino Acid Derivatives via  

E-print Network

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

Zhang, Xumu

133

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

Code of Federal Regulations, 2014 CFR

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

2014-07-01

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

2013-07-01

135

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

Code of Federal Regulations, 2012 CFR

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

2012-07-01

136

Genetics Home Reference: Aromatic l-amino acid decarboxylase deficiency  

MedlinePLUS

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

137

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

138

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

Code of Federal Regulations, 2011 CFR

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

2011-07-01

139

Landscape patterns of free amino acids in arctic tundra soils  

Microsoft Academic Search

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

Knut Kielland

1995-01-01

140

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

141

Inhibitors of Branched Chain Amino Acid Biosynthesis  

NSDL National Science Digital Library

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

142

Residues Within a Conserved Amino Acid Motif of Domains 1 and 4 of VCAM-1 Are Required for Binding to VLA-4  

E-print Network

in the first and fourth domains of VCAM-1. Results based on amino acid substitution mutants demonstrated and disease processes, including rheumatoid arthritis (24, 30, 40, 57), osteoarthritis (24, 30), allogeneic identified on a variety of nonvascular cell types, including follicular dendritic cells (17, 26), bone marrow

Springer, Timothy A.

143

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

144

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

Code of Federal Regulations, 2012 CFR

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

2012-07-01

145

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

Code of Federal Regulations, 2011 CFR

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

2011-07-01

146

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

Code of Federal Regulations, 2014 CFR

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

2014-07-01

147

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

148

Amino acid profile of milk-based infant formulas.  

PubMed

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

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

2000-09-01

149

An Evaluation of the FAO Amino Acid Reference Pattern in Human Nutrition  

Microsoft Academic Search

each amino acid needed for nitrogen equi librium was determined using dietary con ditions wherein the essential amino acids were proportioned as in whole egg pro teins, with the exception of the amino acid under study, and the total nitrogen was maintained at a constant and ade quate level. It appears that the require ments of young women for at

MARIAN E. SWENDSEID; CHERYL L. HARRIS; ANDSTEWART G. TUTTLE

150

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

151

Amino acid sequence of squid troponin C  

Microsoft Academic Search

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

Takao Ojima; Tomokatsu Ohta; Kiyoyoshi Nishita

2001-01-01

152

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

153

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

154

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. PMID:20719949

Ramachandran, Aparna; Horvath, Curt M.

2010-01-01

155

Amino acids in the Yamato carbonaceous chrondrite from Antarctica  

NASA Technical Reports Server (NTRS)

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

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

1979-01-01

156

Amino acids in modern and fossil woods  

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

157

Amino Acid Odorants Stimulate Microvillar Sensory Neurons  

Microsoft Academic Search

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

David L. Lipschitz; William C. Michel

2002-01-01

158

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

E-print Network

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

Xia, Xuhua

159

Original article Rumen effective degradability of amino acids  

E-print Network

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

Paris-Sud XI, Université de

160

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 cerevisiæ 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. PMID:22489878

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

2012-01-01

161

Distinguishing Proteins From Arbitrary Amino Acid Sequences  

PubMed Central

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

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

2015-01-01

162

Distinguishing proteins from arbitrary amino Acid sequences.  

PubMed

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

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

2015-01-01

163

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

164

Amino acid uptake in rust fungi  

PubMed Central

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

Struck, Christine

2015-01-01

165

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

PubMed

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

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

2007-01-01

166

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

167

Interactive Hangman teaches amino acid structures and abbreviations.  

PubMed

We developed an interactive exercise to teach students how to draw the structures of the 20 standard amino acids and to identify the one-letter abbreviations by modifying the familiar game of "Hangman." Amino acid structures were used to represent single letters throughout the game. To provide additional practice in identifying structures, hints to the answers were written in "amino acid sentences" for the students to translate. Students were required to draw the structure of the corresponding letter they wished to guess on a whiteboard. Each student received a reference sheet of the structures and abbreviations, but was required to draw from memory when guessing a letter. Preassessments and postassessments revealed a drastic improvement in the students' ability to recognize and draw structures from memory. This activity provides a fun, educational game to play in biochemistry discussion sections or during long incubations in biochemistry laboratories. PMID:25345852

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

2014-01-01

168

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

169

Terahertz broadband spectroscopic investigations of amino acid  

NASA Astrophysics Data System (ADS)

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

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

2011-08-01

170

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

171

The Genetics of Heteromeric Amino Acid Transporters  

NSDL National Science Digital Library

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

Manuel Palacín (University of Barcelona Department of Biochemistry and Molecular Biology)

2005-04-01

172

New Glycoprotein-Associated Amino Acid Transporters  

Microsoft Academic Search

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

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

1999-01-01

173

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

Microsoft Academic Search

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

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

2006-01-01

174

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

175

Original article Ileal true digestibility of amino acids  

E-print Network

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

Paris-Sud XI, Université de

176

Specific lysosomal transport of small neutral amino acids  

SciTech Connect

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

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

1986-05-01

177

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

178

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. PMID:15240255

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

2004-01-01

179

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. PMID:22230793

Boudko, Dmitri Y.

2012-01-01

180

FLU, an amino acid substitution model for influenza proteins  

PubMed Central

Background The amino acid substitution model is the core component of many protein analysis systems such as sequence similarity search, sequence alignment, and phylogenetic inference. Although several general amino acid substitution models have been estimated from large and diverse protein databases, they remain inappropriate for analyzing specific species, e.g., viruses. Emerging epidemics of influenza viruses raise the need for comprehensive studies of these dangerous viruses. We propose an influenza-specific amino acid substitution model to enhance the understanding of the evolution of influenza viruses. Results A maximum likelihood approach was applied to estimate an amino acid substitution model (FLU) from ~113, 000 influenza protein sequences, consisting of ~20 million residues. FLU outperforms 14 widely used models in constructing maximum likelihood phylogenetic trees for the majority of influenza protein alignments. On average, FLU gains ~42 log likelihood points with an alignment of 300 sites. Moreover, topologies of trees constructed using FLU and other models are frequently different. FLU does indeed have an impact on likelihood improvement as well as tree topologies. It was implemented in PhyML and can be downloaded from ftp://ftp.sanger.ac.uk/pub/1000genomes/lsq/FLU or included in PhyML 3.0 server at http://www.atgc-montpellier.fr/phyml/. Conclusions FLU should be useful for any influenza protein analysis system which requires an accurate description of amino acid substitutions. PMID:20384985

2010-01-01

181

Optimization of short amino acid sequences classifier  

NASA Astrophysics Data System (ADS)

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

Barcz, Aleksy; Szyma?ski, Zbigniew

182

Intestinal metabolism of sulfur amino acids  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

183

Amino acid substitution matrices from protein blocks  

Microsoft Academic Search

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

Steven Henikoff; Jorja G. Henikoff

1992-01-01

184

Amino acid profile in Down's syndrome.  

PubMed Central

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

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

1996-01-01

185

Amino Acid Metabolism of Pea Leaves  

PubMed Central

In the young leaves of pea (Pisum sativum L.) plants, there was a diurnal variation in the levels of amino acids. In the light, total amino nitrogen increased for the first few hours, then stabilized; in the dark, there was a transient decrease followed by a gradual recovery. Asparagine, homoserine, alanine, and glutamine accounted for much of these changes. The incorporation of 15N into various components of the young leaves was followed after supply of 15N-nitrate. 15N appeared most rapidly in ammonia, due to reduction in the leaf, and this process took place predominantly in the light. A large proportion of the primary assimilation took place through the amide group of glutamine, which became labeled and turned over rapidly; labeling of glutamic acid and alanine was also rapid. Asparagine (amide group) soon became labeled and showed considerable turnover. Slower incorporation and turnover were found for aspartic acid, ?-aminobutyric acid, and homoserine. Synthesis and turnover of all of the amino acids continued at a low rate in the dark. ?-Aminobutyric acid was the only compound found to label more rapidly in the dark than in the light. PMID:16659967

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

1977-01-01

186

A model of proteolysis and amino acid biosynthesis for Lactobacillus delbrueckii subsp. bulgaricus in whey.  

PubMed

Lactobacillus delbrueckii subsp. bulgaricus 2038 (L. bulgaricus 2038) is a bacterium that is used as a starter for dairy products by Meiji Co., Ltd of Japan. Culturing L. bulgaricus 2038 with whey as the sole nitrogen source results in a shorter lag phase than other milk proteins under the same conditions (carbon source, minerals, and vitamins). Microarray results of gene expression revealed characteristics of amino acid anabolism with whey as the nitrogen source and established a model of proteolysis and amino acid biosynthesis for L. bulgaricus. Whey peptides and free amino acids are readily metabolized, enabling rapid entry into the logarithmic growth phase. The oligopeptide transport system is the primary pathway for obtaining amino acids. Amino acid biosynthesis maintains the balance between amino acids required for cell growth and the amount obtained from environment. The interconversion of amino acids is also important for L. bulgaricus 2038 growth. PMID:22986815

Liu, Enuo; Zheng, Huajun; Hao, Pei; Konno, Tomonobu; Yu, Yao; Kume, Hisae; Oda, Munehiro; Ji, Zai-Si

2012-12-01

187

FREE AMINO ACID CONTENT OF EWE UTERINE FLUID  

E-print Network

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

Paris-Sud XI, Université de

188

Pre-and post-calving plasma-free amino acids in high-yielding dairy cows  

E-print Network

Pre- and post-calving plasma-free amino acids in high-yielding dairy cows G Piva, F Masoero, L, Italy Glutamine, glutamic acid, methionine, and phenyl- alanine are thought to be limiting amino acids in early lactating animals. A possible approach to estimate the amino-acid requirements of the very high

Paris-Sud XI, Université de

189

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

190

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

191

How Do Haloarchaea Synthesize Aromatic Amino Acids?  

PubMed Central

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

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

2014-01-01

192

Alterations of Amino Acid Level in Depressed Rat Brain  

PubMed Central

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

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

2014-01-01

193

Fatty acid-amino acid conjugates diversification in Lepidopteran caterpillars  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

194

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

195

Single amino acid supplementation in aminoacidopathies: a systematic review  

PubMed Central

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

2014-01-01

196

Branched-Chain Amino Acid Metabolism in Arabidopsis thaliana  

PubMed Central

Valine, leucine and isoleucine form the small group of branched-chain amino acids (BCAAs) classified by their small branched hydrocarbon residues. Unlike animals, plants are able to de novo synthesize these amino acids from pyruvate, 2-oxobutanoate and acetyl-CoA. In plants, biosynthesis follows the typical reaction pathways established for the formation of these amino acids in microorganisms. Val and Ile are synthesized in two parallel pathways using a single set of enzymes. The pathway to Leu branches of from the final intermediate of Val biosynthesis. The formation of this amino acid requires a three-step pathway generating a 2-oxoacid elongated by a methylene group. In Arabidopsis thaliana and other Brassicaceae, a homologous three-step pathway is also involved in Met chain elongation required for the biosynthesis of aliphatic glucosinolates, an important class of specialized metabolites in Brassicaceae. This is a prime example for the evolutionary relationship of pathways from primary and specialized metabolism. Similar to animals, plants also have the ability to degrade BCAAs. The importance of BCAA turnover has long been unclear, but now it seems apparent that the breakdown process might by relevant under certain environmental conditions. In this review, I summarize the current knowledge about BCAA metabolism, its regulation and its particular features in Arabidopsis thaliana. PMID:22303262

Binder, Stefan

2010-01-01

197

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

198

A search for extraterrestrial amino acids in carbonaceous Antarctic micrometeorites  

NASA Technical Reports Server (NTRS)

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.

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

1998-01-01

199

Unnatural amino acids in novel antibody conjugates.  

PubMed

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

Hallam, Trevor J; Smider, Vaughn V

2014-07-01

200

Variation in competitive abilities of plants and microbes for specific amino acids  

Microsoft Academic Search

Microbes are assumed to possess strong competitive advantages over plants for uptake of nutrients from the soil. The finding\\u000a that non-mycorrhizal plants can obtain a significant fraction of their N requirement from soil amino acids contradicts this\\u000a assumption. The amino acid glycine (Gly) has been used as a model amino acid in many recent studies. Our preliminary studies\\u000a showed that

D. A. Lipson; T. K. Raab; S. K. Schmidt; R. K. Monson

1999-01-01

201

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

202

Analysis of free amino acids in green coffee beans  

Microsoft Academic Search

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

Ulrike Arnold; Eberhard Ludwig

1996-01-01

203

Proteins: From Structural Classification to Amino Acid Interaction Networks  

E-print Network

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

Boyer, Edmond

204

Original article Comparison of nucleic and amino acid sequences and  

E-print Network

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

Boyer, Edmond

205

Stochastic Analysis of Amino Acid Substitution in Protein Synthesis  

E-print Network

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

de Vink, Erik

206

Highly Efficient Synthesis of Chiral -Amino Acid Derivatives via  

E-print Network

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

Zhang, Xumu

207

Original article Whole blood and plasma amino acid transfers across  

E-print Network

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

Paris-Sud XI, Université de

208

Exploring the Overproduction of Amino Acids Using the Bilevel Optimization  

E-print Network

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

Maranas, Costas

209

ASTROCHEMISTRY Radiolysis and radioracemization of 20 amino acids  

E-print Network

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

210

Chemoenzymatic Synthesis of Unnatural Amino Acids via Modified Claisen  

E-print Network

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

Hudlicky, Tomas

211

Amino Acids DOI: 10.1002/anie.200602801  

E-print Network

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

Lectka, Thomas

212

Jacobs University Bremen Encoding of Amino Acids and Proteins  

E-print Network

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

Henkel, Werner

213

Reconstructing Amino Acid Interaction Networks by an Ant Colony Approach  

E-print Network

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

Paris-Sud XI, Université de

214

Racemic amino acids from the ultraviolet photolysis of  

E-print Network

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

215

Chemical Genetic Programming The Effect of Evolving Amino Acids  

E-print Network

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

Fernandez, Thomas

216

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

217

Efficient Synthesis of Enantiopure -Amino--Keto Acids from  

E-print Network

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

Hergenrother, Paul J.

218

Protein structures uncovered Amino acids are molecules and are the  

E-print Network

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

Rambaut, Andrew

219

Regulatory Roles of Amino Acids in Immune Response  

Microsoft Academic Search

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

Junya Yoneda; Ayatoshi Andou; Kenji Takehana

2009-01-01

220

Different and overlapping functions of Arabidopsis LHT6 and AAP1 transporters in root amino acid uptake  

PubMed Central

Plants acquire nitrogen in the form of amino acids from the soil, and transport proteins located in the plasma membrane of root cells are required for this process. It was found that the Arabidopsis lysine-histidine-like transporter LHT6 is expressed in root cells important for amino acid uptake, including the epidermis, root hairs, and cortex. Transport studies with lht6 mutants using high levels of amino acids demonstrated that LHT6 is in fact involved in amino acid uptake. To determine if LHT6 plays a role in nitrogen acquisition at soil amino acid concentrations, growth and uptake studies were performed with low levels of toxic amino acid analogues and radiolabelled amino acids, respectively. In addition, mutants of AAP1, another root amino acid transporter, and lht6/aap1 double mutants were examined. The results showed that LHT6 is involved in uptake of acidic amino acids, glutamine and alanine, and probably phenylalanine. LHT6 seems not to transport basic or other neutral amino acids, or, alternatively, other transporters might compensate for eliminated LHT6 function. Previous studies suggested that AAP1 only takes up amino acids at high concentrations; however, here it is demonstrated that the transporter functions in acquisition of glutamate and neutral amino acids when present at soil concentrations. When comparing the characterized root uptake systems, it appears that transporters both with overlapping substrate specificity and with preference for specific substrates are required to access the soil amino acid pool. PMID:25005136

Perchlik, Molly; Foster, Justin; Tegeder, Mechthild

2014-01-01

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. PMID:24587851

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

2014-01-01

222

Branched-chain Amino Acid Metabolon  

PubMed Central

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

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

2010-01-01

223

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

E-print Network

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

Paris-Sud XI, Université de

224

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

PubMed

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

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

2014-01-01

225

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

226

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

227

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

NASA Astrophysics Data System (ADS)

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

Tarasevych, Arkadii V.; Guillemin, Jean-Claude

228

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

E-print Network

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

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

229

Amino acid regulation of autophagy through the GPCR TAS1R1-TAS1R3  

PubMed Central

Cells require the ability to rapidly detect decreases in concentrations of free amino acids so that homeostatic mechanisms, including autophagy, can be engaged to replenish amino acids. Amino acids are transported into cells where it is generally accepted that they are detected by an intracellular sensor. We now show that the cell surface G protein coupled receptor (GPCR) TAS1R1-TAS1R3 (T1R1-T1R3) can sense extracellular amino acids, activate MTORC1, and inhibit autophagy. This receptor is expressed in most tissues and fasted TAS1R3?/? mice have increased autophagy in the heart, skeletal muscle and liver. PMID:23222068

Wauson, Eric M.; Zaganjor, Elma; Cobb, Melanie H.

2013-01-01

230

Structure-function relationships of heterodimeric amino acid transporters  

Microsoft Academic Search

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

Stefan Bröer; Carsten A. Wagner

2002-01-01

231

Amino acid enantiomer excesses in meteorites: origin and significance  

NASA Astrophysics Data System (ADS)

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

Cronin, J. R.; Pizzarello, S.

1999-01-01

232

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

PubMed

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

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

2005-01-01

233

Isotope composition of carbon in amino acids of solid bitumens  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

234

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

235

The Next Generation MOD: A Microchip Amino Acid Analyzer for Detecting Extraterrestrial Life  

NASA Technical Reports Server (NTRS)

The MOD (Mars Organic Detector) instrument which has selected for the definition phase of the BEDS package on the 2005 Mars Explorer Program spacecraft is designed to simply detect the presence of amino acids in Martian surface samples at a sensitivity of a few parts per billion (ppb). An additional important aspect of amino acid analyses of Martian samples is identifying and quantifying which compounds are present, and also distinguishing those produced abiotically from those synthesized by either extinct or extant life. Amino acid homochirality provides an unambiguous way of distinguishing between abiotic vs. biotic origins. Proteins made up of mixed D- and L-amino acids would not likely have been efficient catalysts in early organisms because they could not fold into bioactive configurations such as the a-helix. However, enzymes made up of all D-amino acids function just as well as those made up of only L-amino acids, but the two enzymes use the opposite stereoisomeric substrates. There are no biochemical reasons why L-amino acids would be favored over Damino acids. On Earth, the use of only L-amino acids in proteins by life is probably simply a matter of chance. We assume that if proteins and enzymes were a component of extinct or extant life on Mars, then amino acid homochirality would have been a requirement. However, the possibility that Martian life was (or is) based on D-amino acids would be equal to that based on L-amino acids. The detection of a nonracemic mixture of amino acids in a Martian sample would be strong evidence for the presence of an extinct or extant biota on Mars. The finding of an excess of D-amino acids would provide irrefutable evidence of unique Martian life that could not have been derived from seeding the planet with terrestrial life (or the seeding of the Earth with Martian life). In contrast, the presence of racemic amino acids, along with non-protein amino acids such as alpha-aminoisobutyric acid and isovaline, would be indicative of an abiotic origin, although we have to consider the possibility that the racemic amino acids were generated from the racemization of biotically produced amino acids.

Mathies, R. A.; Hutt, L. D.; Bada, J. L.; Glavin, D.; Grunthaner, F. J.; Grunthaner, P. J.

2000-01-01

236

Role of amino acids and vitamins in nutrition of mesophilic Methanococcus spp  

SciTech Connect

In this study the authors found that autotrophic methanococci similar to Methanococcus maripaludis obtained up to 57% of their cellular carbon from exogeneous amino acids. About 85% of the incorporation was into protein. Primarily nonpolar and basic amino acids and glycine were incorporated; only small amounts of acidic and some polar amino acids were taken up. An additional 10% of the incorporation was into the nucleic acid fraction. Because little /sup 14/CO/sub 2/ was formed from the /sup 14/C-amino acids, little metabolism of the amino acids occurred. Therefore, the growth stimulation by amino acids was probably due to the sparing of anabolic energy requirements. Of the amino acids incorporated, only alanine was also a sole nitrogen source for these methanococci. In contrast, Methanococcus vannielii and Methanococcus aeolicus are autotrophic methanococci which did not incorporate amino acids and did not utilize alanine as a sole nitrogen source. Although glutamine served as a sole nitrogen source for the autotrophic methanococci and Methanococcus voltae, a heterotrophic methanococcus, growth was due to chemical deamination in the medium. M. voltae requires leucine and isoleucine for growth. However, these amino acids were not significant nitrogen sources, and alanine was not a sole nitrogen source for the growth of M. voltae. The branched-chain amino acids were not extensively metabolized by M. voltae. Pantoyl lactone and pantoic acid were readily incorporated by M. voltae. The intact vitamin pantothenate was neither stimulatory to growth nor incorporated. In conclusion, although amino acids and vitamins are nutritionally important to both autotrophic and heterotrophic methanococci, generally they are not subject to extensive catabolism.

Whitman, W.B.; Sohn, S.; Kuk, S.; Xing, R.

1987-10-01

237

Running Head: Amino acid inhibition of Agrp gene expression  

E-print Network

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

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

238

Accumulated analyses of amino acid precursors in returned lunar samples  

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

239

NUTRITIONAL AND FUNCTIONAL IMPORTANCE OF INTESTINAL SULFUR AMINO ACID METABOLISM  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

240

Hybrid polypeptides: gabapentin as a stereochemically constrained ?-amino acid residue.  

PubMed

The design of folded structures in peptides containing the higher homologues of ?-amino acid residues requires the restriction of the range of local conformational choices. In ?-amino acids stereochemically constrained residues like ?,?-dialkylated residue, aminoisobutyric acid (Aib), and D-Proline ((D)Pro) have proved extremely useful in the design of helices and hairpins in short peptides. Extending this approach, backbone substitution and cyclization are anticipated to be useful in generating conformationally constrained ?- and ?-residues. This brief review provides a survey of work on hybrid peptide sequences concerning the conformationally constrained ?-amino acid residue 1-aminomethyl cyclohexane acetic acid, gabapentin (Gpn). This achiral, ?,?-disubstituted, ?-residue strongly favors gauche-gauche conformations about the C(?)-C(?) (?(2)) and C(?)-C(?) (?(1)) bonds, facilitating local folding. The Gpn residue can adopt both C(7) (NH(i)?CO(i)) and C(9) (CO(i-1)?NH(i+1)) hydrogen bonds which are analogous to the C(5) and C(7) (?-turn) conformations at ?-residues. In conjunction with adjacent residues, Gpn may be used in ?? and ?? segments to generate C(12) hydrogen bonded conformations which may be considered as expanded analogs of conventional ?-turns. The structural characterization of C(12) helices, C(12)/C(10) helices with mixed hydrogen bond directionalities and ?-hairpins incorporating Gpn residues at the turn segment is illustrated. PMID:20564041

Balaram, Padmanabhan

2010-01-01

241

Synthesis of alpha-amino acids  

DOEpatents

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

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

1983-01-01

242

Synthesis of alpha-amino acids  

DOEpatents

A method for synthesizing alpha amino acids proceeding through novel intermediates of the formulas: R.sub.1 R.sub.2 C(OSOCl)CN, R.sub.1 R.sub.2 C(Cl)CN and [R.sub.1 R.sub.2 C(CN)O].sub.2 SO wherein R.sub.1 and R.sub.2 are each selected from hydrogen monovalent substituted and unsubstituted hydrocarbon radicals of 1 to 12 carbon atoms. The use of these intermediates allows the synthesis steps to be exothermic and results in an overall synthesis method which is faster than the synthesis methods of the prior art.

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

1983-01-01

243

Synthesis of alpha-amino acids  

DOEpatents

A method for synthesizing alpha amino acids proceding through novel intermediates of the formulas: R.sub.1 R.sub.2 C(OSOCl)CN, R.sub.1 R.sub.2 C(Cl)CN and [R.sub.1 R.sub.2 C(CN)O].sub.2 SO wherein R.sub.1 and R.sub.2 are each selected from hydrogen monovalent substituted and unsubstituted hydrocarbon radicals of 1 to 12 carbon atoms. The use of these intermediates allows the synthesis steps to be exothermic and results in an overall synthesis method which is faster than the synthesis methods of the prior art.

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

1983-01-01

244

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

245

Biosynthesis of 'essential' amino acids by scleractinian corals.  

PubMed Central

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

Fitzgerald, L M; Szmant, A M

1997-01-01

246

Biosynthesis of glycosylphosphatidylinositol (GPI)-anchored membrane proteins in intact cells: specific amino acid requirements adjacent to the site of cleavage and GPI attachment  

PubMed Central

Mutational studies were previously carried out at the omega site intact cells (Micanovic, R., L. Gerber, J. Berger, K. Kodukula, and S. Udenfriend. 1990. Proc. Natl. Acad. Sci. USA. 87:157-161; Micanovic R., K. Kodukula, L. Gerber, and S. Udenfriend. 1990. Proc. Natl. Acad. Sci. USA: 87:7939-7943) and at the omega + 1 and omega + 2 sites in a cell- free system (Gerber, L., K. Kodukula, and S. Udenfriend. 1992. J. Biol. Chem. 267:12168-12173) of nascent proteins destined to be processed to a glycosylphosphatidyl-inositol (GPI)-anchored form. We have now mutated the omega + 1 and omega + 2 sites in placental alkaline phosphatase (PLAP) cDNA and transfected the wild-type and mutant cDNAs into COS 7 cells. Only glycine at the omega + 2 site yielded enzymatically active GPI membrane-anchored PLAP in amounts comparable to the wild type (alanine). Serine was less active and threonine and valine yielded very low but significant activity. By contrast the omega + 1 site was promiscuous, with only proline being inactive. These and the previous studies indicate that the omega and omega + 2 sites of a nascent protein are key determinants for recognition by COOH-terminal signal transamidase. Comparisons have been made to specific requirements for substitution at the -1, -3 sites of amino terminal signal peptides for recognition by NH2-terminal signal peptidase and the mechanisms of NH2 and COOH-terminal signaling are compared. PMID:8425894

1993-01-01

247

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...

248

Amino acid substitutions of cysteine residues near the amino terminus of Wheat streak mosaic virus HC-Pro abolishes virus transmission by the wheat curl mite  

Technology Transfer Automated Retrieval System (TEKTRAN)

The amino-terminal half of HC-Pro of Wheat streak mosaic virus (WSMV) is required for semi-persistent transmission by the wheat curl mite (Aceria tosichella Keifer). The amino-proximal region of WSMV HC-Pro is cysteine-rich with a zinc finger-like motif. Amino acid substitutions were made in this re...

249

Twenty natural amino acids identification by a photochromic sensor chip.  

PubMed

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

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

2015-01-20

250

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

251

Diversity of amino acids in a typical chernozem of Moldova  

NASA Astrophysics Data System (ADS)

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

Frunze, N. I.

2014-12-01

252

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

253

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

PubMed

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

Hayashi, Nobuyuki; Jin, Shigeki; Ujihara, Tomomi

2012-11-01

254

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

E-print Network

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

Cain, Natalie Elaine

255

Amino acid sequence of the human fibronectin receptor  

Microsoft Academic Search

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

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

1987-01-01

256

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

E-print Network

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

Risinger, April L. (April Lynn)

2007-01-01

257

Assembly of the herpes simplex virus capsid: requirement for the carboxyl-terminal twenty-five amino acids of the proteins encoded by the UL26 and UL26.5 genes.  

PubMed Central

Herpes simplex virus type 1 (HSV-1) intermediate capsids are composed of seven proteins, VP5, VP19C, VP21, VP22a, VP23, VP24, and VP26, and the genes that encode these proteins, UL19, UL38, UL26, UL26.5, UL18, UL26, and UL35, respectively. The UL26 gene encodes a protease that cleaves itself and the product of the UL26.5 gene at a site (M site) 25 amino acids from the C terminus of these two proteins. In addition, the protease cleaves itself at a second site (R site) between amino acids 247 and 248. Cleavage of the UL26 protein gives rise to the capsid proteins VP21 and VP24, and cleavage of the UL26.5 protein gives rise to the capsid protein VP22a. Previously we described the production of HSV-1 capsids in insect cells by infecting the cells with recombinant baculoviruses expressing the six capsid genes (D. R. Thomsen, L. L. Roof, and F. L. Homa, J. Virol. 68:2442-2457, 1994). Using this system, we demonstrated that the products of the UL26 and/or UL26.5 genes are required as scaffolds for assembly of HSV-1 capsids. To better understand the functions of the UL26 and UL26.5 proteins in capsid assembly, we constructed baculoviruses that expressed altered UL26 and UL26.5 proteins. The ability of the altered UL26 and UL26.5 proteins to support HSV-1 capsid assembly was then tested in insect cells. Among the specific mutations tested were (i) deletion of the C-terminal 25 amino acids from the proteins coded for by the UL26 and UL26.5 genes; (ii) mutation of His-61 of the UL26 protein, an amino acid required for protease activity; and (iii) mutation of the R cleavage site of the UL26 protein. Analysis of the capsids formed with wild-type and mutant proteins supports the following conclusions: (i) the C-terminal 25 amino acids of the UL26 and UL26.5 proteins are required for capsid assembly; (ii) the protease activity associated with the UL26 protein is not required for assembly of morphologically normal capsids; and (iii) the uncleaved forms of the UL26 and UL26.5 proteins are employed in assembly of 125-nm-diameter capsids; cleavage of these proteins occurs during or subsequent to capsid assembly. Finally, we carried out in vitro experiments in which the major capsid protein VP5 was mixed with wild-type or truncated UL26.5 protein and then precipitated with a VP5-specific monoclonal antibody.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:7745718

Thomsen, D R; Newcomb, W W; Brown, J C; Homa, F L

1995-01-01

258

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

E-print Network

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

Li, Shih-ming

2012-01-01

259

INCAP studies of energy, amino acids, and protein.  

PubMed

This Special Issue summarizes the results of several studies aimed at providing information on a series of questions related to the adequate protein and energy intakes that allow adequate growth and function in children and work performance and productivity in adults. The effect of different sources of protein on nitrogen balance and the requirements of essential amino acids in young children were also explored in fully recovered, previously malnourished children housed in the Metabolic Ward of the Biomedical Division of INCAP. The following are the main results of these investigations: Animal experiments and studies in children recovering from protein-energy malnutrition (PEM) strongly suggest that even when requirements of all nutrients are satisfied, inactivity reduces the rate of linear growth and physical activity improves it as well as lean body mass repletion. The effects of different energy intakes on nitrogen balance demonstrated how energy intake modifies the need to ingest different amounts of protein to satisfy protein requirements. Insensible nitrogen losses in preschool children and their relation to protein intake was demonstrated. The quality of even "good protein sources" modifies the amount needed to satisfy nitrogen requirements, and corn and bean-based diets can satisfy protein needs for health and even growth of young children. Essential amino acid requirements of 2-year-old children was assessed by diverse measurements of nitrogen metabolism and amino acid levels in blood, and were found lower than those recommended by FAO-WHO. In rural adult populations the relationship between energy and protein intake, productivity and body composition, and the impact of environmental hygiene on nitrogen balance was demonstrated and measured. PMID:20461903

Viteri, Fernando E

2010-03-01

260

Kinetic Trapping of Metastable Amino Acid Polymorphs  

PubMed Central

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

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

2014-01-01

261

Coherent manipulation of free amino acids fluorescence.  

PubMed

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

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

2012-07-14

262

Detection of neutral amino acid substitutions in proteins.  

PubMed Central

The field of biochemical genetics relies heavily upon the detection by electrophoresis of genetically determined variants of proteins. Most of these variants differ by substitutions that involve charged amino acids. Genetic variants of another large class, ones that involve substitutions among neutral amino acids, are not easily detected and are often ignored. Ampholyte isoelectric focusing in some cases can separate proteins indistinguishable by standard electrophoresis, including genetic variants of mouse hemoglobins that differ only by neutral amino acid substitutions. A revolutionary variation of isoelectric focusing, in which gradients covering a small pH range are fixed into place in a polyacrylamide gel, provides greater resolution of these nearly identical proteins. Mouse hemoglobin tetramers that differ only by the substitution of alanine for glycine in the alpha-globin chains are resolved by several millimeters with the new technique; by comparison, these tetramers are imperfectly resolved on a standard pH 7-9 isoelectric focusing gel. This improved technique of isoelectric focusing was used to identify a variety of previously unreported genetic variants of mouse hemoglobin alpha chains. Immobilized gradients tailored to the requirements of the proteins being analyzed will extend greatly the ranges of protein variations that can be easily recognized for diverse applications, including genetic quality-control analyses and in studies of genetics, mutagenesis, and evolution. Images PMID:3865185

Whitney, J B; Cobb, R R; Popp, R A; O'Rourke, T W

1985-01-01

263

Understanding and identifying amino acid repeats  

PubMed Central

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

Nijveen, Harm

2014-01-01

264

Amino acid fermentation at the origin of the genetic code.  

PubMed

There is evidence that the genetic code was established prior to the existence of proteins, when metabolism was powered by ribozymes. Also, early proto-organisms had to rely on simple anaerobic bioenergetic processes. In this work I propose that amino acid fermentation powered metabolism in the RNA world, and that this was facilitated by proto-adapters, the precursors of the tRNAs. Amino acids were used as carbon sources rather than as catalytic or structural elements. In modern bacteria, amino acid fermentation is known as the Stickland reaction. This pathway involves two amino acids: the first undergoes oxidative deamination, and the second acts as an electron acceptor through reductive deamination. This redox reaction results in two keto acids that are employed to synthesise ATP via substrate-level phosphorylation. The Stickland reaction is the basic bioenergetic pathway of some bacteria of the genus Clostridium. Two other facts support Stickland fermentation in the RNA world. First, several Stickland amino acid pairs are synthesised in abiotic amino acid synthesis. This suggests that amino acids that could be used as an energy substrate were freely available. Second, anticodons that have complementary sequences often correspond to amino acids that form Stickland pairs. The main hypothesis of this paper is that pairs of complementary proto-adapters were assigned to Stickland amino acids pairs. There are signatures of this hypothesis in the genetic code. Furthermore, it is argued that the proto-adapters formed double strands that brought amino acid pairs into proximity to facilitate their mutual redox reaction, structurally constraining the anticodon pairs that are assigned to these amino acid pairs. Significance tests which randomise the code are performed to study the extent of the variability of the energetic (ATP) yield. Random assignments can lead to a substantial yield of ATP and maintain enough variability, thus selection can act and refine the assignments into a proto-code that optimises the energetic yield. Monte Carlo simulations are performed to evaluate the establishment of these simple proto-codes, based on amino acid substitutions and codon swapping. In all cases, donor amino acids are assigned to anticodons composed of U+G, and have low redundancy (1-2 codons), whereas acceptor amino acids are assigned to the the remaining codons. These bioenergetic and structural constraints allow for a metabolic role for amino acids before their co-option as catalyst cofactors. PMID:22325238

de Vladar, Harold P

2012-01-01

265

Amino acid fermentation at the origin of the genetic code  

PubMed Central

There is evidence that the genetic code was established prior to the existence of proteins, when metabolism was powered by ribozymes. Also, early proto-organisms had to rely on simple anaerobic bioenergetic processes. In this work I propose that amino acid fermentation powered metabolism in the RNA world, and that this was facilitated by proto-adapters, the precursors of the tRNAs. Amino acids were used as carbon sources rather than as catalytic or structural elements. In modern bacteria, amino acid fermentation is known as the Stickland reaction. This pathway involves two amino acids: the first undergoes oxidative deamination, and the second acts as an electron acceptor through reductive deamination. This redox reaction results in two keto acids that are employed to synthesise ATP via substrate-level phosphorylation. The Stickland reaction is the basic bioenergetic pathway of some bacteria of the genus Clostridium. Two other facts support Stickland fermentation in the RNA world. First, several Stickland amino acid pairs are synthesised in abiotic amino acid synthesis. This suggests that amino acids that could be used as an energy substrate were freely available. Second, anticodons that have complementary sequences often correspond to amino acids that form Stickland pairs. The main hypothesis of this paper is that pairs of complementary proto-adapters were assigned to Stickland amino acids pairs. There are signatures of this hypothesis in the genetic code. Furthermore, it is argued that the proto-adapters formed double strands that brought amino acid pairs into proximity to facilitate their mutual redox reaction, structurally constraining the anticodon pairs that are assigned to these amino acid pairs. Significance tests which randomise the code are performed to study the extent of the variability of the energetic (ATP) yield. Random assignments can lead to a substantial yield of ATP and maintain enough variability, thus selection can act and refine the assignments into a proto-code that optimises the energetic yield. Monte Carlo simulations are performed to evaluate the establishment of these simple proto-codes, based on amino acid substitutions and codon swapping. In all cases, donor amino acids are assigned to anticodons composed of U+G, and have low redundancy (1-2 codons), whereas acceptor amino acids are assigned to the the remaining codons. These bioenergetic and structural constraints allow for a metabolic role for amino acids before their co-option as catalyst cofactors. Reviewers: this article was reviewed by Prof. William Martin, Prof. Eörs Szathmáry (nominated by Dr. Gáspár Jékely) and Dr. Ádám Kun (nominated by Dr. Sandor Pongor) PMID:22325238

2012-01-01

266

Complexing of Amino Acids to DNA by Chromate in Intact Cells  

E-print Network

Using o-pthaldialdehyde (OPT) fluorescence, the amino acids associated with DNA were studied following exposure of intact Chinese hamster ovary cells to chromate. Rigorous extraction with EDTA, acid, or base was required to release the amino acids cross-linked to the DNA isolated from control or chromate-treated cells by standard procedures (i.e., proteinase K, phenol, etc.). Amino acids resisting extraction from DNA were not studied since analysis was limited to those that could be released by these procedures. There was a chromate dose-dependent increase in amino acids complexed with the DNA that could be released by EDTA, acid, and base, and these amino acids were separated by HPLC and identified. Substantial increases in cysteine, glutamine, glutamic acid, histidine, threonine, and tyrosine were found as a function of increasing concentrations of chromate. There was also a time-dependent increase in complexing of these amino acids to the DNA by chromate. The amino acids found complexed to DNA in intact cells by chromate were thought to originate from reactions of free amino acids or small peptides with the DNA rather than being proteolytic products derived from larger proteins that were cross-linked to the DNA. This was supported by a number of experiments: a) free amino acids or bovine serum albumin (BSA) were cross-linked by chromium to DNA in vitro and the DNA was isolated by standard procedures. With BSA, few amino acids were found cross-linked to the DNA, but with free amino acids, numerous amino acids were associated with DNA; b) when radiolabelled threonine complexed to the DNA was examined in the absence and presence of a protein synthesis inhibitor, there was substantial stimulation of the threonine complex to DNA by chromate when protein synthesis was inhibited with cyclohexamide; c) there were substantial increases in amino acids associated with DNA isolated without protease. Not only does the cross-linking of amino acids to DNA represent a new type of lesion to study in intact cells but it may also be a useful biomarker of human exposure to cross-linking agents.- Environ Health Perspect 102(Suppl 3):251-255 (1994).

Victoria Voitkun; Anatoly Zhitkovich; Max Costa

267

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

E-print Network

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

Wehrli, Bernhard

268

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

PubMed

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

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

2008-01-01

269

Amino Acids Regulate Transgene Expression in MDCK Cells  

PubMed Central

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

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

2014-01-01

270

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

271

Proton-assisted amino acid transporters are conserved regulators of proliferation and amino acid-dependent mTORC1 activation  

PubMed Central

The PI3-kinase (PI3K)/Akt and downstream mammalian target of rapamycin complex 1 (mTORC1) signalling cascades promote normal growth and are frequently hyperactivated in tumour cells. mTORC1 is also regulated by local nutrients, particularly amino acids, but the mechanisms involved are poorly understood. Unexpectedly, members of the proton-assisted amino acid transporter (PAT or SLC36) family emerged from in vivo genetic screens in Drosophila as transporters with uniquely potent effects on mTORC1-mediated growth. Here we show the two human PATs that are widely expressed in normal tissues and cancer cell lines, PAT1 and PAT4, behave similarly to fly PATs when expressed in Drosophila. siRNA knockdown reveals that these molecules are required for activation of mTORC1 targets and for proliferation in human MCF-7 breast cancer and HEK-293 embryonic kidney cell lines. Furthermore, activation of mTORC1 in starved HEK-293 cells stimulated by amino acids requires PAT1 and PAT4, and is elevated in PAT1-overexpressing cells. Importantly, in HEK-293 cells, PAT1 is highly concentrated in intracellular compartments, including endosomes, where mTOR shuttles upon amino acid stimulation. Our data are therefore consistent with a model in which PATs modulate mTORC1's activity not by transporting amino acids into the cell, but by modulating the intracellular response to amino acids. PMID:20498635

Heublein, S; Kazi, S; Ögmundsdóttir, M H; Attwood, E V; Kala, S; Boyd, C A R; Wilson, C; Goberdhan, D C I

2011-01-01

272

The amino acid composition of estuarine colloidal material  

NASA Astrophysics Data System (ADS)

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

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

1983-07-01

273

Essential dietary amino acids for growth of larvae of the yellow mealworm, Tenebrio molitor L.  

PubMed

Larvae of the yellow mealworm, Tenebrio molitor L., have been used to evaluate nutritional quality of proteins and protein isolates. However, such investigations have been complicated by lack of knowledge of dietary requirements of the larvae. To determine essential dietary amino acids for growth of Tenebrio molitor, single amino acids were deleted from the amino acid mixture of the diet. Diets were maintained isonitrogenous with supplementary glycine and, in the case of deleted glycine, with glutamic acid. Growth, as measured by gain in weight, and survival were observed over a 4-week period at 27 plus or minus 0.25 degrees and 65 plus or minus 5% relative humidity. The results indicate that larvae of Tenebrio molitor require a dietary source of the same 10 amino acids essential for growth in rats, other vertebrates, and some protozoa. They also showed that serine, tyrosine, glutamic acid, and possibly glycine were dispensable for growth in this insect. Alanine, cystine, proline, and aspartic acid appeared semidispensable. Survival over the 4-week experimental period was unaffected by deleting amino acids from the diet. The results are discussed in relation to amino acid requirements of other insects and to suggested improvement of the diet of the present investigation. PMID:1142013

Davis, G R

1975-08-01

274

Small-intestinal or colonic microbiota as a potential amino acid source in animals.  

PubMed

Factors affecting physiological impacts of the microbiome on protein nutrition are discussed for hind-gut fermenters (humans, pigs, rodents). The microbiome flourishes in all gastrointestinal organs, and is a major source of amino acids to fore-gut fermenting animals. In humans, rats and pigs the net effect of microbiome biomass synthesis on amino acid requirements is much less certain. Dietary proteins, amino acids, peptides, endogenous-secreted protein and recycled urea may all be utilized as nitrogen source by growing bacteria in the small intestine and colon. The inclusions of radiolabelled amino acid precursors will result in labeled bacteria which can be digested and absorbed in the ileum and to some degree in the colon. This does not necessarily indicate a significant nutritional role of the microbiome in humans, pigs and rodents. The physiological attributes required for small-intestinal and colon microbiome utilization are a vigorous proteolytic digestion with pancreatic or intestinal enzymes and the presence of amino acid transporters. Findings to date seem to suggest that these two physiological attributes for effective bacterial protein utilization are present in the small intestine; however, these attributes have a much lower capacity/impact in the colon. The gastrointestinal microbiome is likely a protein source of medium to high nutritional quality, but overall the microbiome is not an important amino acid source in humans and animals fed amino acids at requirement levels. PMID:25466904

Bergen, Werner G

2015-02-01

275

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

NASA Astrophysics Data System (ADS)

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

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

1988-05-01

276

Polymerization of beta-amino acids in aqueous solution  

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

277

Boron containing amino acid compounds and methods for their use  

SciTech Connect

The present invention provides new boron containing amino acid compounds and methods for making these compounds by contacting melphalan or another nitrogen mustard derivative and sodium borocaptate. The present invention also provides a method of treating a mammal having a tumor by administering to the mammal a therapeutically effective amount of the new boron containing amino acid compounds.

Glass, J.D.; Coderre, J.A.

2000-01-25

278

Amino Acids Availability of Poultry Feedstuffs in Pakistan  

Microsoft Academic Search

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

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

279

The amino acid sequence of snapping turtle (Chelydra serpentina) ribonuclease  

Microsoft Academic Search

Snapping turtle (Chelydra serpentina) ribonuclease was isolated from pancreatic tissue. Turtle ribonuclease binds much more weakly to the affinity chromatography matrix used than mammalian ribonucleases. The amino acid sequence was determined from overlapping peptides obtained from three different digests. The N-terminal amino acid sequence of the protein determined by others and homology were used as additional evidence for several overlaps.

Cornelis Schüller; Jaap J. Beintema; Jaap Broos; Janneke Meulenberg

1985-01-01

280

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

281

Vitreous Amino Acid Concentrations in Patients With Glaucoma Undergoing Vitrectomy  

Microsoft Academic Search

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

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

2003-01-01

282

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

283

Prediction of protein antigenic determinants from amino acid sequences  

Microsoft Academic Search

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

T. P. Hopp; K. R. Woods

1981-01-01

284

Site specific incorporation of keto amino acids into proteins  

DOEpatents

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

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

2008-10-07

285

Site specific incorporation of keto amino acids into proteins  

SciTech Connect

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

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

2011-12-06

286

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

287

Site specific incorporation of keto amino acids into proteins  

SciTech Connect

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

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

2009-04-28

288

Site specific incorporation of keto amino acids into proteins  

SciTech Connect

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

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

2012-02-14

289

Interactive Hangman Teaches Amino Acid Structures and Abbreviations  

ERIC Educational Resources Information Center

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

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

2014-01-01

290

EFFECT OF LEAD ON GAMMA AMINO BUTYRIC ACID SYNTHESIS  

EPA Science Inventory

The project studies the inhibitory effect of lead on the enzymatic activity of brain glutamic amino acid decarboxylase (GADC). The enzyme is responsible for the catalytic formation of gamma amino butyric acid (GABA) inhibitory neurons which is believed to be involved with the tra...

291

Rapid and Precise Determination of Cellular Amino Acid Flux Rates  

E-print Network

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

Wikswo, John

292

Parenteral amino acid intakes in critically ill children  

Technology Transfer Automated Retrieval System (TEKTRAN)

Parenteral amino acid formulas used in parenteral nutrition have a variable composition. To determine the amino acid intake of parenterally fed, critically ill children, and compare it with recommended dietary allowances (RDA) established by the Institute of Medicine (IOM), we retrospectively review...

293

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.

294

INTESTINAL SULFUR AMINO ACID METABOLISM IN NEONATAL PIGLETS  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

295

Amino acids control ammonia pulses in yeast colonies  

Microsoft Academic Search

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

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

2002-01-01

296

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

297

Abnormalities of cerebrospinal fluid amino-acids in purulent meningitis  

PubMed Central

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

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

1979-01-01

298

Role of sialic acid in synaptosomal transport of amino acid transmitters  

SciTech Connect

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

Zaleska, M.M.; Erecinska, M.

1987-03-01

299

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

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

300

Single amino acids in sucrose rewards modulate feeding and associative learning in the honeybee  

PubMed Central

Obtaining the correct balance of nutrients requires that the brain integrates information about the body’s nutritional state with sensory information from food to guide feeding behaviour. Learning is a mechanism that allows animals to identify cues associated with nutrients so that they can be located quickly when required. Feedback about nutritional state is essential for nutrient balancing and could influence learning. How specific this feedback is to individual nutrients has not often been examined. Here, we tested how the honeybee’s nutritional state influenced the likelihood it would feed on and learn sucrose solutions containing single amino acids. Nutritional state was manipulated by pre-feeding bees with either 1 M sucrose or 1 M sucrose containing 100 mM of isoleucine, proline, phenylalanine, or methionine 24 h prior to olfactory conditioning of the proboscis extension response. We found that bees pre-fed sucrose solution consumed less of solutions containing amino acids and were also less likely to learn to associate amino acid solutions with odours. Unexpectedly, bees pre-fed solutions containing an amino acid were also less likely to learn to associate odours with sucrose the next day. Furthermore, they consumed more of and were more likely to learn when rewarded with an amino acid solution if they were pre-fed isoleucine and proline. Our data indicate that single amino acids at relatively high concentrations inhibit feeding on sucrose solutions containing them, and they can act as appetitive reinforcers during learning. Our data also suggest that select amino acids interact with mechanisms that signal nutritional sufficiency to reduce hunger. Based on these experiments, we predict that nutrient balancing for essential amino acids during learning requires integration of information about several amino acids experienced simultaneously. PMID:24819203

Simcock, Nicola K.; Gray, Helen E.; Wright, Geraldine A.

2014-01-01

301

Extraterrestrial amino acids identified in metal-rich CH and CB carbonaceous chondrites from Antarctica  

NASA Astrophysics Data System (ADS)

Carbonaceous chondrites contain numerous indigenous organic compounds and could have been an important source of prebiotic compounds required for the origin of life on Earth or elsewhere. Extraterrestrial amino acids have been reported in five of the eight groups of carbonaceous chondrites and are most abundant in CI, CM, and CR chondrites but are also present in the more thermally altered CV and CO chondrites. We report the abundance, distribution, and enantiomeric and isotopic compositions of simple primary amino acids in six metal-rich CH and CB carbonaceous chondrites that have not previously been investigated for amino acids: Allan Hills (ALH) 85085 (CH3), Pecora Escarpment (PCA) 91467 (CH3), Patuxent Range (PAT) 91546 (CH3), MacAlpine Hills (MAC) 02675 (CBb), Miller Range (MIL) 05082 (CB), and Miller Range (MIL) 07411 (CB). Amino acid abundances and carbon isotopic values were obtained by using both liquid chromatography time-of-flight mass spectrometry and fluorescence, and gas chromatography isotope ratio mass spectrometry. The ?13C/12C ratios of multiple amino acids fall outside of the terrestrial range and support their extraterrestrial origin. Extracts of CH chondrites were found to be particularly rich in amino acids (13-16 parts per million, ppm) while CB chondrite extracts had much lower abundances (0.2-2 ppm). The amino acid distributions of the CH and CB chondrites were distinct from the distributions observed in type 2 and 3 CM and CR chondrites and contained elevated levels of ?-, ?-, and ?-amino acids compared to the corresponding ?-amino acids, providing evidence that multiple amino acid formation mechanisms were important in CH and CB chondrites.

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

2013-03-01

302

Matrix effects in the derivatization of amino acids with 9-fluorenylmethyl chloroformate and phenylisothiocyanate.  

PubMed

Pre-column derivatization of amino acids is widely practiced today for the HPLC analysis of amino acids. Due to the requirement for pH control, excess reagent removal and multi-step manipulations, automation is a major challenge in the derivatization of amino acids. Another challenge for pre-column chemistries is the effect of matrices in the sample such as salts, buffers and surfactants. This paper reports on automated derivatization using phenylisothiocyanate (PITC) and compares matrix effects between this PITC method and that of derivatization using 9-fluorenylmethyl chloroformate (FMOC). An autosampler was programmed to mix amino acid samples with PITC or FMOC reagent, allow a programmed reaction time, extract excess reagent and finally inject onto the HPLC. To study sample matrix effects, amino acid samples were spiked with various concentrations of Tris-HCl, phenol, citrate, sulfosalicylic acid, sodium chloride and sodium dodecyl sulfate. Using the PITC method and the FMOC method, the recoveries of amino acids in varied sample matrices were compared to pure amino acid standards. The PITC method appears to be affected less by matrix effects than the FMOC method. However, the FMOC method has a higher sensitivity so that sample dilution (up to 30 times) can be used to eliminate matrix effects. PMID:1931023

Lai, F; Mayer, A; Sheehan, T

1991-08-01

303

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

304

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

PubMed Central

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

Macnicol, Peter K.

1983-01-01

305

Phenotypic and genotypic analysis of amino acid auxotrophy in Lactobacillus helveticus CNRZ 32.  

PubMed

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. PMID:17993552

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

2008-01-01

306

Chemical interaction between titanium implant surface and amino acids.  

PubMed

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

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

2007-03-01

307

Mating frequency influences nectar amino acid preference of Pieris napi.  

PubMed Central

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

Mevi-Schütz, Jovanne; Erhardt, Andreas

2004-01-01

308

Evolution of a Genome-Encoded Bias in Amino Acid Biosynthetic Pathways Is a Potential Indicator of Amino Acid Dynamics in the Environment  

PubMed Central

Overcoming the stress of starvation is one of an organism’s most challenging phenotypic responses. Those organisms that frequently survive the challenge, by virtue of their fitness, will have evolved genomes that are shaped by their specific environments. Understanding this genotype–environment–phenotype relationship at a deep level will require quantitative predictive models of the complex molecular systems that link these aspects of an organism’s existence. Here, we treat one of the most fundamental molecular systems, protein synthesis, and the amino acid biosynthetic pathways involved in the stringent response to starvation. These systems face an inherent logical dilemma: Building an amino acid biosynthetic pathway to synthesize its product—the cognate amino acid of the pathway—may require that very amino acid when it is no longer available. To study this potential “catch-22,” we have created a generic model of amino acid biosynthesis in response to sudden starvation. Our mathematical analysis and computational results indicate that there are two distinctly different outcomes: Partial recovery to a new steady state, or full system failure. Moreover, the cell’s fate is dictated by the cognate bias, the number of cognate amino acids in the corresponding biosynthetic pathway relative to the average number of that amino acid in the proteome. We test these implications by analyzing the proteomes of over 1,800 sequenced microbes, which reveals statistically significant evidence of low cognate bias, a genetic trait that would avoid the biosynthetic quandary. Furthermore, these results suggest that the pattern of cognate bias, which is readily derived by genome sequencing, may provide evolutionary clues to an organism’s natural environment. PMID:25118252

Fasani, Rick A.; Savageau, Michael A.

2014-01-01

309

Synthesis and chirality of amino acids under interstellar conditions.  

PubMed

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

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

2013-01-01

310

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

PubMed

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. PMID:24016666

Murakami, Taro; Yoshinaga, Mariko

2013-10-01

311

An amino acid substitution-selection model adjusts residue fitness to improve phylogenetic estimation.  

PubMed

Standard protein phylogenetic models use fixed rate matrices of amino acid interchange derived from analyses of large databases. Differences between the stationary amino acid frequencies of these rate matrices from those of a data set of interest are typically adjusted for by matrix multiplication that converts the empirical rate matrix to an exchangeability matrix which is then postmultiplied by the amino acid frequencies in the alignment. The result is a time-reversible rate matrix with stationary amino acid frequencies equal to the data set frequencies. On the basis of population genetics principles, we develop an amino acid substitution-selection model that parameterizes the fitness of an amino acid as the logarithm of the ratio of the frequency of the amino acid to the frequency of the same amino acid under no selection. The model gives rise to a different sequence of matrix multiplications to convert an empirical rate matrix to one that has stationary amino acid frequencies equal to the data set frequencies. We incorporated the substitution-selection model with an improved amino acid class frequency mixture (cF) model to partially take into account site-specific amino acid frequencies in the phylogenetic models. We show that 1) the selection models fit data significantly better than corresponding models without selection for most of the 21 test data sets; 2) both cF and cF selection models favored the phylogenetic trees that were inferred under current sophisticated models and methods for three difficult phylogenetic problems (the positions of microsporidia and breviates in eukaryote phylogeny and the position of the root of the angiosperm tree); and 3) for data simulated under site-specific residue frequencies, the cF selection models estimated trees closer to the generating trees than a standard ? model or cF without selection. We also explored several ways of estimating amino acid frequencies under neutral evolution that are required for these selection models. By better modeling the amino acid substitution process, the cF selection models will be valuable for phylogenetic inference and evolutionary studies. PMID:24441033

Wang, Huai-Chun; Susko, Edward; Roger, Andrew J

2014-04-01

312

Human L-type amino acid transporter 1 (LAT1): characterization of function and expression in tumor cell lines  

Microsoft Academic Search

System L is a major nutrient transport system responsible for the transport of large neutral amino acids including several essential amino acids. We previously identified a transporter (L-type amino acid transporter 1: LAT1) subserving system L in C6 rat glioma cells and demonstrated that LAT1 requires 4F2 heavy chain (4F2hc) for its functional expression. Since its oncofetal expression was suggested

Osamu Yanagida; Yoshikatsu Kanai; Arthit Chairoungdua; Do Kyung Kim; Hiroko Segawa; Tomoko Nii; Seok Ho Cha; Hirotaka Matsuo; Jun-ichi Fukushima; Yoshiki Fukasawa; Yoshiko Tani; Yutaka Taketani; Hiroshi Uchino; Ju Young Kim; Jun Inatomi; Isao Okayasu; Ken-ichi Miyamoto; Eiji Takeda; Tomoyuki Goya; Hitoshi Endou

2001-01-01

313

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

314

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

Code of Federal Regulations, 2012 CFR

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

2012-07-01

315

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

316

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

Code of Federal Regulations, 2014 CFR

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

2014-07-01

317

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

318

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

Code of Federal Regulations, 2014 CFR

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

2014-07-01

319

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

320

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

321

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

Code of Federal Regulations, 2012 CFR

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

2012-07-01

322

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

323

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

Code of Federal Regulations, 2011 CFR

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

2011-07-01

324

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

Code of Federal Regulations, 2012 CFR

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

2012-07-01

325

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

E-print Network

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

Zhang, Jianzhi

326

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

E-print Network

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

Wurtman, Richard

327

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

Code of Federal Regulations, 2012 CFR

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

2012-07-01

328

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

Code of Federal Regulations, 2011 CFR

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

2011-07-01

329

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

330

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

Code of Federal Regulations, 2014 CFR

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

2014-07-01

331

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

Code of Federal Regulations, 2014 CFR

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

2014-07-01

332

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

Code of Federal Regulations, 2014 CFR

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

2014-07-01

333

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

Code of Federal Regulations, 2011 CFR

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

2011-07-01

334

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

335

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

Code of Federal Regulations, 2014 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....

2014-07-01

336

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

337

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

E-print Network

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

Kiyonori Yoshii; Naoki Kamo; Kenzo Kurihara

338

TOXICITY OF VARIOUS ORGANIC SULFUR COMPOUNDS FOR CHICKS FED CRYSTALLINE AMINO ACID DIETS CONTAINING THREONINE AND GLYCINE AT THEIR MINIMAL DIETARY REQUIREMENTS FOR MAXIMAL GROWTH  

Microsoft Academic Search

SUMMARY Five growth assays were conducted with young chicks to study relative toxicities of various organic sulfur compounds. Evaluation of the dietary requirements for glycine and threonine indicated that .52% threonine and .51% glycine were the minimum requirements for maximal gain. To provide a margin of safety .55% threonine and .60% glycine were chosen as levels to use in subsequent

Robert S. Katz; David H. Baker

339

How amino acids and peptides shaped the RNA world.  

PubMed

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

van der Gulik, Peter T S; Speijer, Dave

2015-01-01

340

Cerebrospinal fluid amino acids in pathological gamblers and healthy controls.  

PubMed

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

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

2007-01-01

341

Metabolism of tryptophan, methionine and arginine in Diplodus sargus larvae fed rotifers: effect of amino acid supplementation.  

PubMed

Dietary amino acids imbalances have been described when fish larvae are fed rotifers, what may lead to a reduction in growth rate. The tube-feeding technique can be used to assess the effect of free amino acid short term supplementation. In this study supplementation of tryptophan, methionine and arginine were tested in Diplodus sargus. Single crystalline (14)C amino acids as well as a mix of (14)C amino acids were used as tracers to compare results of individual amino acids metabolism with the average of all amino acids. The results show low absorption efficiencies for tryptophan (70%) and arginine (80%) and similar absorption for methionine (90%) when compared with the average of all amino acids. Supplementation of these amino acids seems to be viable but it did not result in higher retention compared to the amino acid mix. This means that tryptophan, methionine and arginine are probably not the limiting amino acid when Diplodus sargus larvae are fed rotifers. However, supplementation in these IAA may be required for their roles as precursors of important molecules other than proteins, in order to improve larval quality and/or performance. PMID:18204926

Saavedra, M; Conceição, L E C; Pousão-Ferreira, P; Dinis, M T

2008-06-01

342

Characterisation of dissolved combined amino acids in marine waters.  

PubMed

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

Sommerville, K; Preston, T

2001-01-01

343

Experimental and Theoretical Studies on the Rearrangement of 2-Oxoazepane ?,?-Amino Acids into 2'-Oxopiperidine ?(2,3,3) -Amino Acids: An Example of Intramolecular Catalysis.  

PubMed

Enantiopure ?-amino acids represent interesting scaffolds for peptidomimetics, foldamers and bioactive compounds. However, the synthesis of highly substituted analogues is still a major challenge. Herein, we describe the spontaneous rearrangement of 4-carboxy-2-oxoazepane ?,?-amino acids to lead to 2'-oxopiperidine-containing ?(2,3,3) -amino acids, upon basic or acid hydrolysis of the 2-oxoazepane ?,?-amino acid ester. Under acidic conditions, a totally stereoselective synthetic route has been developed. The reordering process involved the spontaneous breakdown of an amide bond, which typically requires strong conditions, and the formation of a new bond leading to the six-membered heterocycle. A quantum mechanical study was carried out to obtain insight into the remarkable ease of this rearrangement, which occurs at room temperature, either in solution or upon storage of the 4-carboxylic acid substituted 2-oxoazepane derivatives. This theoretical study suggests that the rearrangement process occurs through a concerted mechanism, in which the energy of the transition states can be lowered by the participation of a catalytic water molecule. Interestingly, it also suggested a role for the carboxylic acid at position?4 of the 2-oxoazepane ring, which facilitates this rearrangement, participating directly in the intramolecular catalysis. PMID:25522111

Núñez-Villanueva, Diego; Bonache, M Ángeles; Lozano, Laura; Infantes, Lourdes; Elguero, José; Alkorta, Ibon; García-López, M Teresa; González-Muñiz, Rosario; Martín-Martínez, Mercedes

2015-02-01

344

Amino acid utilization by Aerobacter aerogenes and Escherichia coli  

E-print Network

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

Herrera, Rodolfo Eduardo

1938-01-01

345

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

346

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

347

Amino acid signalling upstream of mTOR  

PubMed Central

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

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

2014-01-01

348

Inhibitors of amino acids biosynthesis as antifungal agents.  

PubMed

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

Jastrz?bowska, Kamila; Gabriel, Iwona

2015-02-01

349

The effect of dietary amino acid composition on egg production in blue tits  

PubMed Central

Most studies on the interaction between food supply and reproduction in animals have assumed that energy is likely to be the factor limiting egg number and/or size. In this paper, we investigate whether dietary protein proximately constrains egg production in birds. We provisioned breeding blue tits with two food supplements that differed only in the concentration of five essential amino acids. Birds receiving a supplementary diet containing an amino acid balance close to that required for egg protein formation laid significantly larger clutches (18% greater) than control birds, whereas birds receiving an otherwise identical supplementary diet but without a favourable amino acid balance did not increase egg production. To our knowledge, this is the first demonstration that dietary amino acid composition may limit egg production in free-living birds.

Ramsay, S. L.; Houston, D. C.

1998-01-01

350

The stability of amino acids at submarine hydrothermal vent temperatures  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

351

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

352

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

353

Ferroelectric studies on amino acids mixed TGSP single crystals  

Microsoft Academic Search

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

G. Arunmozhi; R. Jayavel; C. Subramanian

1998-01-01

354

Taurine: new implications for an old amino acid  

Microsoft Academic Search

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

Georgia B. Schuller-Levis

2003-01-01

355

Amino acid uptake in deciduous and coniferous taiga ecosystems  

Microsoft Academic Search

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

Knut Kielland; Jack McFarland; Karl Olson

2006-01-01

356

Each protein is characterized by its unique sequential order of amino acids, the so-called protein sequence. Biology"s paradigm is that this order of amino acids determines the  

E-print Network

protein-coupled receptors. The TEA method requires a definition of protein subfamilies as an input113 Summary Each protein is characterized by its unique sequential order of amino acids, the so-called protein sequence. Biology"s paradigm is that this order of amino acids determines the protein"s

van den Brink, Jeroen

357

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

E-print Network

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

Reed, Christopher A.

358

Amino acid analysis using core-shell particle column.  

PubMed

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

Song, Yanting; Funatsu, Takashi; Tsunoda, Makoto

2013-05-15

359

On the utility of alternative amino acid scripts.  

PubMed

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

Flower, Darren R

2012-01-01

360

Extraterrestrial Amino Acids in Ureilites Including Almahata Sitta  

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

361

Evaluation of Amino Acids as Turfgrass Nematicides1  

PubMed Central

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

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

2010-01-01

362

Autophagy and aging--importance of amino acid levels.  

PubMed

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

Dröge, Wulf

2004-03-01

363

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

364

The spark discharge synthesis of amino acids from various hydrocarbons  

NASA Technical Reports Server (NTRS)

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

Ring, D.; Miller, S. L.

1984-01-01

365

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

366

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

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

367

Phenotypic and genetic relationships between growth and feed intake curves and feed efficiency and amino acid requirements in the growing pig.  

PubMed

Improvement of feed efficiency in pigs has been achieved essentially by increasing lean growth rate, which resulted in lower feed intake (FI). The objective was to evaluate the impact of strategies for improving feed efficiency on the dynamics of FI and growth in growing pigs to revisit nutrient recommendations and strategies for feed efficiency improvement. In 2010, three BWs, at 35±2, 63±9 and 107±7 kg, and daily FI during this period were recorded in three French test stations on 379 Large White and 327 French Landrace from maternal pig populations and 215 Large White from a sire population. Individual growth and FI model parameters were obtained with the InraPorc® software and individual nutrient requirements were computed. The model parameters were explored according to feed efficiency as measured by residual feed intake (RFI) or feed conversion ratio (FCR). Animals were separated in groups of better feed efficiency (RFI- or FCR-), medium feed efficiency and poor feed efficiency. Second, genetic relationships between feed efficiency and model parameters were estimated. Despite similar average daily gains (ADG) during the test for all RFI groups, RFI- pigs had a lower initial growth rate and a higher final growth rate compared with other pigs. The same initial growth rate was found for all FCR groups, but FCR- pigs had significantly higher final growth rates than other pigs, resulting in significantly different ADG. Dynamic of FI also differed between RFI or FCR groups. The calculated digestible lysine requirements, expressed in g/MJ net energy (NE), showed the same trends for RFI or FCR groups: the average requirements for the 25% most efficient animals were 13% higher than that of the 25% least efficient animals during the whole test, reaching 0.90 to 0.95 g/MJ NE at the beginning of the test, which is slightly greater than usual feed recommendations for growing pigs. Model parameters were moderately heritable (0.30±0.13 to 0.56±0.13), except for the precocity of growth (0.06±0.08). The parameter representing the quantity of feed at 50 kg BW showed a relatively high genetic correlation with RFI (0.49±0.14), and average protein deposition between 35 and 110 kg had the highest correlation with FCR (-0.76±0.08). Thus, growth and FI dynamics may be envisaged as breeding tools to improve feed efficiency. Furthermore, improvement of feed efficiency should be envisaged jointly with new feeding strategies. PMID:25192352

Saintilan, R; Brossard, L; Vautier, B; Sellier, P; Bidanel, J; van Milgen, J; Gilbert, H

2015-01-01

368

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

PubMed

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

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

2014-09-01

369

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

PubMed Central

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

Horn, Lyle W.

1981-01-01

370

Diel and depth variations in dissolved free amino acids and ammonium in the Baltic Sea determined by shipboard HPL Canalysis  

Microsoft Academic Search

A precolumn fluorimetric labeling method was tested for shipboard HPLC analysis of dis- solved fret amino acids (DFAA) in natural waters. No sample preparation is required and all naturally occurring amino acids plus ammonium are sufficiently separated within 30 min, Striking diel trends were observed to a depth of at least 60 m, with maximal DFAA concen- trations (200400 nM)

KENNETH MOPPER; PETER LINDROTH

1982-01-01

371

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

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

372

Amino Acid Supplementation Affects Imprinted Gene Transcription Patterns in Parthenogenetic Porcine Blastocysts  

PubMed Central

To determine whether exogenous amino acids affect gene transcription patterns in parthenogenetic porcine embryos, we investigated the effects of amino acid mixtures in culture medium. Parthenogenetic embryos were cultured in PZM3 medium under four experimental conditions: 1) control (no amino acids except L-glutamine and taurine); 2) nonessential amino acids (NEAA); 3) essential amino acids (EAA); and 4) NEAA and EAA. The rate of development of embryos to the four-cell stage was not affected by treatment. However, fewer (P<0.05) embryos cultured with EAA (12.8%) reached the blastocyst stage as compared with the control group (25.6%) and NEAA group (30.3%). Based on these findings, we identified genes with altered expression in parthenogenetic embryos exposed to medium with or without EAAs. The results indicated that EAA influenced gene expression patterns, particularly those of imprinted genes (e.g., H19, IGF2R, PEG1, XIST). However, NEAAs did not affect impaired imprinted gene expressions induced by EAA. The results also showed that mechanistic target of rapamycin (MTOR) mRNA expression was significantly increased by EAA alone as compared with control cultures, and that the combined treatment with NEAA and EAA did not differ significantly from those of control cultures. Our results revealed that gene transcription levels in porcine embryos changed differentially depending on the presence of EAA or NEAA. However, the changes in the H19 mRNA observed in the parthenogenetic blastocysts expression level was not related to the DNA methylation status in the IGF2/H19 domain. The addition of exogenous amino acid mixtures affected not only early embryonic development, but also gene transcription levels, particularly those of imprinted genes. However, this study did not reveal how amino acids affect expression of imprinted genes under the culture conditions used. Further studies are thus required to fully evaluate how amino acids affect transcriptional regulation in porcine embryos. PMID:25180972

Park, Chi-Hun; Jeong, Young-Hee; Jeong, Yeun-Ik; Kwon, Jeong-Woo; Shin, Taeyoung; Hyun, Sang-Hwan; Jeung, Eui-Bae; Kim, Nam-Hyung; Seo, Sang-Kyo; Lee, Chang-Kyu; Hwang, Woo-Suk

2014-01-01

373

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

PubMed

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

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

2014-05-20

374

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

PubMed

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

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

1995-01-01

375

Boron-containing amino carboxylic acid compounds and uses thereof  

DOEpatents

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

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

2000-03-14

376

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

Microsoft Academic Search

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

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

2009-01-01

377

Fungal Peptaibiotics: Assessing Potential Meteoritic Amino Acid Contamination  

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

378

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

E-print Network

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

Sali, Andrej

379

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

E-print Network

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

Paris-Sud XI, Université de

380

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

E-print Network

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

Carbone, Alessandra

381

Protein digestion and amino acid absorption along the intestine of the common carp (Cyprinus carpio L.),  

E-print Network

Protein digestion and amino acid absorption along the intestine of the common carp (Cyprinus carpio amino acids and the apparent absorption of amino acids (AAaa) were evaluated in different segments of carp intestine. The AAaa analysed using Crz03 as a marker indicated that 73.2 % of the amino acids were

Paris-Sud XI, Université de

382

AMINO ACID CATABOLISM AND GLUCONEOGENESIS IN SHEEP' A.R. EGAN* J.C. MACRAE  

E-print Network

AMINO ACID CATABOLISM AND GLUCONEOGENESIS IN SHEEP' A.R. EGAN* J.C. MACRAE * Waite Agricultural of catabolism of amino acids are well described, there is as yet little information on the relationships bet- ween amino acid supply, flux and oxidation, or on the contribution made by certain amino acids

Paris-Sud XI, Université de

383

Plasma Amino Acids and Insulin Luels in Obesity: Response to Carbohydrate Intake and Tryptophan Supplements  

E-print Network

Plasma Amino Acids and Insulin Luels in Obesity: Response to Carbohydrate Intake and Tryptophan Supplements Benjamin Caballero, Nicholas Finer, and Richard J. Wurtman We assessed the plasma amino acids-chain amino acids, phenylalanine and tyrosine, and the level. of these amino acids declined much less

Wurtman, Richard

384

Seasonal variation of hydrophilic, hydrophobic, and charged amino acids in developing apple flower buds  

Microsoft Academic Search

An increase in polar amino acids especially in hydrophilic and charged amino acids and a decrease in hydrophobic amino acids were observed in developing apple flower buds from July to November (beginning of dormancy). This suggests that polar amino acids may play a role in dormancy of apple flower buds similar to that of other polar substances. A 2nd?degree polynomial

S. Khanizadeh; D. Buszard; C. G. Zarkadas

1994-01-01

385

Accuracy of sequence alignment and fold assessment using reduced amino acid alphabets  

Microsoft Academic Search

Reduced or simplified amino acid alphabets group the 20 naturally occurring amino acids into a smaller number of representative pro- tein residues. To date, several reduced amino acid alphabets have been proposed, which have been derived and optimized by a variety of methods. The resulting reduced amino acid alphabets have been appliedtopatternrecognition,generationofconsen- sus sequences from multiple alignments, protein folding, and

Francisco Melo; Marc A. Marti-Renom

2006-01-01

386

Closed-system behaviour of the intra-crystalline fraction of amino acids in mollusc shells  

Microsoft Academic Search

When mollusc shells are analysed conventionally for amino acid geochronology, the entire population of amino acids is included, both inter- and intra-crystalline. This study investigates the utility of removing the amino acids that are most susceptible to environmental effects by isolating the fraction of amino acids encapsulated within mineral crystals of mollusc shells (intra-crystalline fraction). Bleaching, heating and leaching (diffusive

K. E. H. Penkman; D. S. Kaufman; D. Maddy; M. J. Collins

2008-01-01

387

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

Microsoft Academic Search

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

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

1998-01-01

388

Tandem sulfur-containing amino acids are epicritical determinants of dopamine D(2) receptor pharmacology.  

PubMed

The conserved aspartic acid that is required for ligand binding to the dopamine D(2) receptor is followed by three tandem sulfur-containing amino acids. While previous point mutation studies did not reveal any single one of these residues as being critical for ligand binding, we now show that simultaneously substituting all three with isovolumetric, non sulfur-containing amino acids results in large decreases in the binding affinity for dopamine, (-)-raclopride and 7-(-4(4-(2, 3-dichlorophenyl)-1-piperazinyl)butyloxy)-3, 4-dihydro-2(1H)-quinolinone (aripiprazole), but not for methylspiperone or allosteric modulators. PMID:10666514

Schetz, J A; Sibley, D R

2000-01-28

389

Resolving Discrepancy between Nucleotides and Amino Acids in Deep-Level Arthropod Phylogenomics: Differentiating Serine Codons in 21-Amino-Acid Models  

E-print Network

amino acids. This study investigates the cause of that discrepancy. METHODOLOGY/PRINCIPAL FINIDINGS: The hypothesis is tested that failure to distinguish the serine residues encoded by two disjunct clusters of codons (TCN, AGY) in amino acid analyses...

Zwick, Andreas; Regier, Jerome C.; Zwickl, Derrick J.

2012-11-20

390

The problem of amino acid complementarity and antisense peptides.  

PubMed

The review presents three hypotheses concerning the amino acid complementarity: 1) the Mekler-Blalock antisense hypothesis; 2) the Root-Bernstein approach based on stereochemical complementarity of amino acids and anti-amino acids coded by anticodons read in parallel with the coding DNA strand; 3) Siemion hypothesis resulting from the periodicity of the genetic code. The current state of knowledge as well as the results of the implementations of these hypotheses are compared. A special attention is given to Root-Bernstein and Siemion hypotheses, which differ in only few points of the complementarity prediction. We describe methods of investigation of peptide-antipeptide pairing, including circular dichroism, mass spectrometry, affinity chromatography and other techniques. The biological applications of complementarity principle are considered, such as search for bioeffector-bioreceptor interaction systems, the influence of peptide-antipeptide pairing on the activity of peptide hormones, and the application of antipeptides in immunochemistry. The possible role of amino acid-anti-amino acid interactions in the formation of the spatial structures of peptides, proteins and protein complexes is discussed. Such problems as the pairing preferences of protein-protein interfaces, the role of the pairing in the creation of disulfide bonds and the possible appearance of such interactions in beta-structure are also examined. The main intention of the paper is to bring the complementarity problem to the attention of the scientific community, as a possible tool in proteomics, molecular design and molecular recognition. PMID:15581420

Siemion, Ignacy Z; Cebrat, Marek; Kluczyk, Alicja

2004-12-01

391

Extraction of amino acids by reverse iontophoresis in vivo.  

PubMed

Reverse iontophoresis across the skin is a potentially useful alternative for non-invasive clinical and therapeutic drug monitoring. In this work, the reverse iontophoretic extraction of 17 amino acids was studied in vivo in healthy volunteers. Charged amino acids were primarily extracted towards the electrode of opposite polarity, while zwitterionic species were extracted, more or less equally, to both anode and cathode, suggesting that the net charge on the skin, under the conditions of the experiment, was close to zero. The significant presence of a 'skin reservoir' of several amino acids, presumably originating from the barrier's so-called 'natural moisturizing factor', was deduced from the results. While this phenomenon had been observed in an earlier in vitro investigation, the levels of certain amino acids (including serine and glycine) in the skin were found to be much higher in vivo. Hence, while the results of this study confirm the feasibility of extracting some amino acids at physiologically relevant levels in vivo, the objective of achieving a correlation between iontophoretically extracted fluxes and blood plasma levels may not be a practically realisable goal in all cases. PMID:19347973

Sieg, Anke; Jeanneret, Fabienne; Fathi, Marc; Hochstrasser, Denis; Rudaz, Serge; Veuthey, Jean-Luc; Guy, Richard H; Delgado-Charro, M Begoña

2009-05-01

392

Effect of L-amino acids on Mucor rouxii dimorphism.  

PubMed Central

Mucor rouxii organisms growing aerobically and exponentially on a well-defined minimal medium are able to differentiate as yeasts or as mycelia, depending on the amino acid as the nitrogen source. When certain amino acids were used as the nitrogen source, spores differentiated only as hyphae, whereas other amino acids gave rise to other morphological forms having different ratios of yeasts to hyphae. In both hyphal and yeast cultures, an aerobic metabolism was predominant, as shown by determining several metabolic parameters such as oxygen tension, glucose consumption, ethanol production, and CO2 release. A complete conversion of yeasts to hyphae was obtained by the appropriate change in the amino acid used as nitrogen source. By preparing spheroplasts from mycelial cultures and transferring them to media with amino acids that induce yeast formation, a 50% yield in the reverse transformation was achieved. A correlation between the change in pH of the medium and cell morphology was observed in different growth conditions. Decrease in the pH of the medium preceded the appearance of hyphae. Also, when the initial pH of the medium was increased, aspartate-containing cultures developed mainly as mycelia, instead of yeasts, with a corresponding decrease in the final pH. Images PMID:3096961

Leija, A; Ruiz-Herrera, J; Mora, J

1986-01-01

393

Dietary free amino acids and the gastric phase of digestion.  

PubMed

In the stomach, pre-absorptive perception of food constituents is of particular importance in maintaining secretion and motility that matches the quantity and quality of nutrients. Products of food protein hydrolysis, free amino acids and short peptides, are the most potent chemical stimulants of the gastric phase of digestion. They are recognized by a variety of extracellular receptors belonging to the G-protein-coupled receptor superfamily, which are expressed by gastric mucosal exocrine and endocrine cells. Enteroendocrine G and D cells are likely the first level of integration of amino-acid-induced signals influencing a balance of endocrine activation and inhibition of gastric functions. This review focuses mainly on the physiological significance of dietary L-glutamate (Glu) in control of the gastric phase of digestion. The Glu signaling system in the stomach is linked to activation of the vagal afferents. In contrast to other natural amino acids, luminal Glu activates a paracrine cascade led by nitric oxide and followed by serotonin (5-HT), interacting in turn with 5- HT3 receptors on the afferent endings in the sub-mucosal layer. Glu, the only amino acid regularly ingested in a free form, enhances secretory and gastroprokinetic responses to protein- and amino-acid-rich diets but has no effect when applied alone or with carbohydrates. Possible mechanisms are discussed. PMID:23886390

Zolotarev, Vasiliy A

2014-01-01

394

Amino acid containing glass-ionomer cement for orthopedic applications  

NASA Astrophysics Data System (ADS)

Amino acid containing glass-ionomer cements were synthesized, formulated, and evaluated for orthopedic application. The formulation of different amino acid containing glass-ionomer bone cements was optimized, and conventional and resin-modified glass-ionomer bone cements were compared. Properties of interest included handling characteristics, physical and chemical properties, and mechanical strength of the bone cement. The study was based on the synthesis of different vinyl containing amino acids, different polyelectrolytes containing these amino acid residues, and different resin-modified polyelectrolytes, as well as formulation and evaluation of conventional and resin-modified glass-ionomer bone cements using these polyelectrolytes. Systematic preparation of polyelectrolytes and formulation of glass-ionomer bone cements were essential features of this work, since we anticipated that the mechanical properties of the glass-ionomer bone cements could be strongly affected by the nature of the polyelectrolytes and formulation. Mechanical properties were evaluated in a screw driven mechanical testing machine, and structure-property relationships were determined by scanning electron microscopic (SEM) observation of the fracture surface of the specimens. How the structure of polyelectrolytes, such as different amino acid residues, molecular weight, different modifying resin, and formulation of glass-ionomer bone cement, affected the mechanical properties was also studied.

Wu, Wei

395

Industrial production of amino acids by coryneform bacteria.  

PubMed

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

Hermann, Thomas

2003-09-01

396

De Novo Amino Acid Biosynthesis Contributes to Salmonella enterica Growth in Alfalfa Seedling Exudates.  

PubMed

Salmonella enterica is a member of the plant microbiome. Growth of S. enterica in sprouting-seed exudates is rapid; however, the active metabolic networks essential in this environment are unknown. To examine the metabolic requirements of S. enterica during growth in sprouting-seed exudates, we inoculated alfalfa seeds and identified 305 S. enterica proteins extracted 24 h postinoculation from planktonic cells. Over half the proteins had known metabolic functions, and they are involved in over one-quarter of the known metabolic reactions. Ion and metabolite transport accounted for the majority of detected reactions. Proteins involved in amino acid transport and metabolism were highly represented, suggesting that amino acid metabolic networks may be important for S. enterica growth in association with roots. Amino acid auxotroph growth phenotypes agreed with the proteomic data; auxotrophs in amino acid-biosynthetic pathways that were detected in our screen developed growth defects by 48 h. When the perceived sufficiency of each amino acid was expressed as a ratio of the calculated biomass requirement to the available concentration and compared to growth of each amino acid auxotroph, a correlation between nutrient availability and bacterial growth was found. Furthermore, glutamate transport acted as a fitness factor during S. enterica growth in association with roots. Collectively, these data suggest that S. enterica metabolism is robust in the germinating-alfalfa environment; that single-amino-acid metabolic pathways are important but not essential; and that targeting central metabolic networks, rather than dedicated pathways, may be necessary to achieve dramatic impacts on bacterial growth. PMID:25416761

Kwan, Grace; Pisithkul, Tippapha; Amador-Noguez, Daniel; Barak, Jeri

2015-02-01

397

Structure determination of a 20 amino acid peptide by NMR The twenty amino acid peptide contains over 100 unique protons that are potentially observable by  

E-print Network

Structure determination of a 20 amino acid peptide by NMR The twenty amino acid peptide contains information is helpful: a) A table of typical proton NMR chemical shifts for protons within amino acids of the 20 amino acid peptide. It is: K1 T2 L3 T4 L5 E6 A7 A8 L9 R10 N11 A12 W13 L14 R15 E16 V17 G18 L19 K20

398

Characterization of the system L amino acid transporter in T24 human bladder carcinoma cells  

Microsoft Academic Search

System L is a major nutrient transport system responsible for the Na+-independent transport of large neutral amino acids including several essential amino acids. In malignant tumors, a system L transporter L-type amino acid transporter 1 (LAT1) is up-regulated to support tumor cell growth. LAT1 is also essential for the permeation of amino acids and amino acid-related drugs through the blood–brain

Do Kyung Kim; Yoshikatsu Kanai; Hye Won Choi; Sahatchai Tangtrongsup; Arthit Chairoungdua; Ellappan Babu; Kittipong Tachampa; Naohiko Anzai; Yuji Iribe; Hitoshi Endou

2002-01-01

399

Excretion of amino acids by humans during space flight  

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

400

The Gap1 general amino acid permease acts as an amino acid sensor for activation of protein kinase A targets in the yeast Saccharomyces cerevisiae.  

PubMed

Addition of a nitrogen source to yeast (Saccharomyces cerevisiae) cells starved for nitrogen on a glucose-containing medium triggers activation of protein kinase A (PKA) targets through a pathway that requires for sustained activation both a fermentable carbon source and a complete growth medium (fermentable growth medium induced or FGM pathway). Trehalase is activated, trehalose and glycogen content as well as heat resistance drop rapidly, STRE-controlled genes are repressed, and ribosomal protein genes are induced. We show that the rapid effect of amino acids on these targets specifically requires the general amino acid permease Gap1. In the gap1Delta strain, transport of high concentrations of l-citrulline occurs at a high rate but without activation of trehalase. Metabolism of the amino acids is not required. Point mutants in Gap1 with reduced or deficient transport also showed reduced or deficient signalling. However, two mutations, S391A and S397A, were identified with a differential effect on transport and signalling for l-glutamate and l-citrulline. Specific truncations of the C-terminus of Gap1 (e.g. last 14 or 26 amino acids) did not reduce transport activity but caused the same phenotype as in strains with constitutively high PKA activity also during growth with ammonium as sole nitrogen source. The overactive PKA phenotype was abolished by mutations in the Tpk1 or Tpk2 catalytic subunits. We conclude that Gap1 acts as an amino acid sensor for rapid activation of the FGM signalling pathway which controls the PKA targets, that transport through Gap1 is connected to signalling and that specific truncations of the C-terminus result in permanently activating Gap1 alleles. PMID:14617151

Donaton, Monica C V; Holsbeeks, Inge; Lagatie, Ole; Van Zeebroeck, Griet; Crauwels, Marion; Winderickx, Joris; Thevelein, Johan M

2003-11-01

401

Amino Acids, Aromatic Compounds, and Carboxylic Acids: How Did They Get Their Common Names?  

ERIC Educational Resources Information Center

Surveys the roots of the common names of organic compounds most likely to be encountered by undergraduate organic chemistry students. Includes information for 19 amino acids, 17 aromatic compounds, and 21 carboxylic acids. (WRM)

Leung, Sam H.

2000-01-01

402

Partitioning of acidic, basic and neutral amino acids into imidazolium-based ionic liquids  

Microsoft Academic Search

In this paper, partitioning behaviors of typical neutral (Alanine), acidic (Glutamic acid) and basic (Lysine) amino acids\\u000a into imidazolium-based ionic liquids [C4mim][PF6], [C6mim][PF6], [C8mim][PF6], [C6mim][BF4] and [C8mim][BF4] as extracting solvents were examined. [C6mim][BF4] showed the best efficiency for partitioning of amino acids. The partition coefficients of amino acids in ionic liquids were\\u000a found to depend strongly on pH of the

Ghodratollah AbsalanMorteza Akhond; Morteza Akhond; Leila Sheikhian

2010-01-01

403

The Biology Project: The Chemistry of Amino Acids  

NSDL National Science Digital Library

The Biology Project at the University of Arizona doesn't shy away from the big (or little) questions of life and science, and this helpful educational resource will be another educational arrow in the quiver of science educators from Seattle to Tashkent. The site provides a basic introduction to amino acids, offering a brief description of their role as the "building blocks" of protein. After reading the introduction, students can learn about the structure of amino acids, and then take on a few exercises in the "Test yourself" section of the site. Of course, that's not all, as visitors can also learn about each amino acid separately, and there's even a handy legend that makes learning that much easier.

404

Energetics of amino acid synthesis in hydrothermal ecosystems  

NASA Technical Reports Server (NTRS)

Thermodynamic calculations showed that the autotrophic synthesis of all 20 protein-forming amino acids was energetically favored in hot (100 degrees C), moderately reduced, submarine hydrothermal solutions relative to the synthesis in cold (18 degrees C), oxidized, surface seawater. The net synthesis reactions of 11 amino acids were exergonic in the hydrothermal solution, but all were endergonic in surface seawater. The synthesis of the requisite amino acids of nine thermophilic and hyperthermophilic proteins in a 100 degreesC hydrothermal solution yielded between 600 and 8000 kilojoules per mole of protein, which is energy that is available to drive the intracellular synthesis of enzymes and other biopolymers in hyperthermophiles thriving in these ecosystems.

Amend, J. P.; Shock, E. L.

1998-01-01

405

Amino acids in a Fischer Tropsch type synthesis  

NASA Technical Reports Server (NTRS)

One postulation is described for the presence of organic compounds in meteorites which states that they were formed during the condensation of the solar nebula. A viable laboratory simulation of these conditions can be modeled after the industrial Fischer Tropsch reaction, which is known to produce organic compounds called hydrocarbons. In this simulation, a mixture of carbon monoxide, hydrogen and ammonia is heated in the presence of iron meteorite. The reaction products for amino acids, a class of organic compounds important to life, were examined. A large number of these compounds is found in meteorites and other chemical evolution experiments, but only small quantities of a few amino acids were found in the present simulation work. These results are at odds with the existing literature in which many amino acids were reported.

Brown, D. L.; Lawless, J. G.

1974-01-01

406

Regulation of skeletal muscle proteolysis by amino acids.  

PubMed

Skeletal muscle is the major reservoir of body protein that can be mobilized in a number of muscle wasting conditions, that include kidney failure. Increased proteolysis in such conditions provides free amino acids that are used for acute-phase protein synthesis or that are degraded for energy purposes. Amino acids act as signals to regulate both protein synthesis and protein breakdown. We review the current but limited information available on the regulation of proteolytic systems in muscle cells. In particular, recent data have shown that amino acid deprivation in C2C12 myotubes stimulates autophagic sequestration by mechanisms that implicate the Apg system through a class III phosphoinositide-3'-kinase (PI3K III ) signaling cascade. PMID:15648001

Béchet, Daniel; Tassa, Amina; Combaret, Lydie; Taillandier, Daniel; Attaix, Didier

2005-01-01

407

Transport of aromatic amino acids by Brevibacterium linens.  

PubMed Central

Whole metabolizing Brevibacterium linens cells were used to study the transport of aromatic amino acids. Kinetic results followed the Michaelis-Menten equation with apparent Km values for phenylalanine, tyrosine, and tryptophan of 24, 3.5, and 1.8 microM. Transport of these amino acids was optimum at pH 7.5 and 25 degrees C for phenylalanine and pH 8.0 and 35 degrees C for tyrosine and tryptophan. Crossed inhibitions were all noncompetitive. The only marked stereospecificity was for the L form of phenylalanine. Transport was almost totally inhibited by carbonyl cyanide-m-chlorophenylhydrazone. Iodoacetate and N-ethylmaleimide were much more inhibitory for tryptophan transport than for transport of the other two aromatic amino acids. PMID:6885717

Boyaval, P; Moreira, E; Desmazeaud, M J

1983-01-01

408

Figure 1. Comparison of amino-acid frequencies in predicted disordered (freqdis) and ordered (freqord) regions of human proteins. Amino acids are  

E-print Network

Figure 1. Comparison of amino-acid frequencies in predicted disordered (freqdis) and ordered (freqord) regions of human proteins. Amino acids are sorted by the relative difference (freqdis ­freqord differences between amino acid sequences of IDPs/IDRs and structured globular proteins and domains

Obradovic, Zoran

409

Micro-Detection System for Determination of the Biotic or Abiotic Origin of Amino Acids  

NASA Technical Reports Server (NTRS)

The research carried out under this PIDDP involves the development of a breadboard version of a spacecraft-based system for the detection of amino acid chirality (molecular handedness) on solar system bodies. Chirality provides an unambiguous way of distinguishing between abiotic and biotic origins since only one mirror-image form is used in the functional molecules of life. Recent advances in a variety of nano-fabrication technologies have resulted in concepts for enabling miniaturized chemical and biological analytical systems. These are complete application-specific systems that integrate fluid micro handling systems for extracting and reacting target molecules, micro-separation technologies for enhanced sensitivity and resolution, and advanced detection technologies. This effort makes use of a relatively new technology that shows demonstrated promise for spacecraft-based amino acid analysis: microchip-based capillary electrophoresis (muCE). The muCE system is capable of analyzing the type of amino acids present as well as the relative amounts of their mirror image forms. The system we developed will be able to chirally resolve all of the major amino acids found in extraterrestrial material (Gly, Ala, Val, Pro, Asp, Glu, a-aminoisobutyric acid, and isovaline) at sub-part-per-billion levels. The _CE analysis requires that the amino acids be extracted from the sample and derivatized for either optical or electrochemical detection. In our implementation, the amino acids are released from the sample by sublimation and prepared for muCE analysis using a microfluidic circuit. In addition, we have investigated the use of a microfluidic circuit for the release of amino acids from samples in which sublimation has proven to be problematic.

Bada, Jeffrey L.

2003-01-01

410

Enrichment of amino acid-oxidizing, acetate-reducing bacteria.  

PubMed

In anaerobic condition, amino acids are oxidatively deaminated, and decarboxylated, resulting in the production of volatile fatty acids. In this process, excess electrons are produced and their consumption is necessary for the accomplishment of amino acid degradation. In this study, we anaerobically constructed leucine-degrading enrichment cultures from three different environmental samples (compost, excess sludge, and rice field soil) in order to investigate the diversity of electron-consuming reaction coupled to amino acid oxidation. Constructed enrichment cultures oxidized leucine to isovalerate and their activities were strongly dependent on acetate. Analysis of volatile fatty acids (VFAs) profiles and community structure analysis during batch culture of each enrichment indicated that Clostridium cluster I coupled leucine oxidation to acetate reduction in the enrichment from the compost and the rice field soil. In these cases, acetate was reduced to butyrate. On the other hand, Clostridium cluster XIVb coupled leucine oxidation to acetate reduction in the enrichment from the excess sludge. In this case, acetate was reduced to propionate. To our surprise, the enrichment from rice field soil oxidized leucine even in the absence of acetate and produced butyrate. The enrichment would couple leucine oxidation to reductive butyrate synthesis from CO2. The coupling reaction would be achieved based on trophic link between hydrogenotrophic acetogenic bacteria and acetate-reducing bacteria by sequential reduction of CO2 and acetate. Our study suggests anaerobic degradation of amino acids is achieved yet-to-be described reactions. PMID:24630616

Ato, Makoto; Ishii, Masaharu; Igarashi, Yasuo

2014-08-01

411

Solution nonideality related to solute molecular characteristics of amino acids.  

PubMed Central

By measuring the freezing-point depression for dilute, aqueous solutions of all water-soluble amino acids, we test the hypothesis that nonideality in aqueous solutions is due to solute-induced water structuring near hydrophobic surfaces and solute-induced water destructuring in the dipolar electric fields generated by the solute. Nonideality is expressed with a single solute/solvent interaction parameter I, calculated from experimental measure of delta T. A related parameter, I(n), gives a method of directly relating solute characteristics to solute-induced water structuring or destructuring. I(n)-values correlate directly with hydrophobic surface area and inversely with dipolar strength. By comparing the nonideality of amino acids with progressively larger hydrophobic side chains, structuring is shown to increase with hydrophobic surface area at a rate of one perturbed water molecule per 8.8 square angstroms, implying monolayer coverage. Destructuring is attributed to dielectric realignment as described by the Debye-Hückel theory, but with a constant separation of charges in the amino-carboxyl dipole. By using dimers and trimers of glycine and alanine, this destructuring is shown to increase with increasing dipole strength using increased separation of fixed dipolar charges. The capacity to predict nonideal solution behavior on the basis of amino acid characteristics will permit prediction of free energy of transfer to water, which may help predict the energetics of folding and unfolding of proteins based on the characteristics of constituent amino acids. Images FIGURE 6 PMID:7711253

Keener, C R; Fullerton, G D; Cameron, I L; Xiong, J

1995-01-01

412

The amino acid sequence of reeves' pheasant (Syrmaticus reevesii) lysozyme.  

PubMed

The amino acid sequence of reeves' pheasant lysozyme was analyzed. Carboxymethylated lysozyme was digested with trypsin and resulting peptides were analyzed using the DABITC/PITC double coupling manual Edman method. The established amino acid sequence had seven substitutions, Tyr3, Leu15, His41, His77, Ser79, Arg102, and Asn121, compared with hen egg-white lysozyme. Ser79 was the first found in a bird lysozyme. A substitution in the active site was found in position 102 which has been considered to participate in the substrate binding at subsites A-C. PMID:1368713

Araki, T; Kuramoto, M; Torikata, T

1991-07-01

413

Protein conjugation with genetically encoded unnatural amino acids  

PubMed Central

The site-specific incorporation of unnatural amino acids with orthogonal chemical reactivity into proteins enables the synthesis of structurally-defined protein conjugates. Amino acids containing ketone, azide, alkyne, alkene, and tetrazine side chains can be genetically encoded in response to nonsense and frameshift codons. These bio-orthogonal chemical handles allow precise control over the site and stoichiometry of conjugation, and have enabled medicinal chemistry-like optimization of the physical and biological properties of protein conjugates, especially the next-generation protein therapeutics. PMID:23664497

Kim, Chan Hyuk; Axup, Jun Y.; Schultz, Peter G.

2014-01-01

414

Utilization of sorghum grain protein and amino acids by cattle  

E-print Network

UTILIZATION OF SORG!VJH GRAIN PROTFIN AND AMINO ACIDS BY CATTLE A Thesis GLEN RAY HENDERSON Submitted to tne Gr duate ColleEe of Texas A&li Unirersity ln partial fulfillment of the reRuirement for the deSree of BASTER OF SC1ENCE January 1970... Najor Subject Ar. imal Nutrition UTILIZATION OF SORGHUM GRAIN PROTEIN AND AMINO ACIDS BY CATTLE A Thesis by GLEN RAY HENDF. RSON Approved as to style and content by: (Head of Department) (M ber) January 1970 ABSTPACT Utilization of Sorghum...

Henderson, Glen Ray

2012-06-07

415

Branched-chain amino acids in liver diseases.  

PubMed

Branched chain amino acids (BCAAs) have been shown to affect gene expression, protein metabolism, apoptosis and regeneration of hepatocytes, and insulin resistance. They have also been shown to inhibit the proliferation of liver cancer cells in vitro, and are essential for lymphocyte proliferation and dendritic cell maturation. In patients with advanced chronic liver disease, BCAA concentrations are low, whereas the concentrations of aromatic amino acids such as phenylalanine and tyrosine are high, conditions that may be closely associated with hepatic encephalopathy and the prognosis of these patients. Based on these basic observations, patients with advanced chronic liver disease have been treated clinically with BCAA-rich medicines, with positive effects. PMID:24282351

Tajiri, Kazuto; Shimizu, Yukihiro

2013-11-21

416

Amino acid functionalised calixarenes: crystal growth modifiers and low molecular weight gelators.  

E-print Network

??A selection of amino acid functionalised calix[4]arenes was studied. Acidic amino acid functionalised calixarenes were investigated as crystal growth modifiers. The self-assembly behaviour of proline… (more)

Goh, Ching Yong

2012-01-01

417

Main-Chain Conformational Tendencies of Amino Acids Robert J. Anderson,1,2  

E-print Network

Main-Chain Conformational Tendencies of Amino Acids Robert J. Anderson,1,2 Zhiping Weng,2 Robert K tendencies of an amino acid. Despite forty years of research, the shape of Ramachandran plots is still tendencies among amino acids, and showed that the conformational relationships of amino ac- ids are well

Weng, Zhiping

418

Amino acid and protein volumes A novel evaluation of residue and protein volumes  

E-print Network

Amino acid and protein volumes 1 A novel evaluation of residue and protein volumes by means - Paris 7, INTS, 6, rue Alexandre Cabanel, 75739 Paris Cedex 15, France Short title: Amino acid and Modeling 2010;50(5):947-60" DOI : 10.1021/ci9004892 #12;Amino acid and protein volumes 2 Abstract Amino

Paris-Sud XI, Université de

419

A Catalytic Asymmetric Method for the Synthesis of -Unsaturated -Amino Acid Derivatives  

E-print Network

A Catalytic Asymmetric Method for the Synthesis of -Unsaturated -Amino Acid Derivatives Alice E for the synthesis of -unsaturated -amino acids and their corresponding 1,3-amino alcohol derivatives to the -unsaturated -amino acid derivatives of high enantiopurity. Introduction The development of synthetically

Walsh, Patrick J.

420

A Test of Amino Acid Reversibility Nick G.C. Smith, Adam Eyre-Walker  

E-print Network

A Test of Amino Acid Reversibility Nick G.C. Smith, Adam Eyre-Walker Centre for the Study no evidence to reject the assumption of reversibility in protein evolution. Key words: Amino acid evolution the evolution of proteins, it is generally assumed that the number of substitutions from amino acid X to amino

Eyre-Walker, Adam

421

Enhanced amino acid selection in fully evolved tryptophanyl-tRNA synthetase, relative to its urzyme, requires domain motion sensed by the D1 switch, a remote dynamic packing motif.  

PubMed

We previously showed (Li, L., and Carter, C. W., Jr. (2013) J. Biol. Chem. 288, 34736-34745) that increased specificity for tryptophan versus tyrosine by contemporary Bacillus stearothermophilus tryptophanyl-tRNA synthetase (TrpRS) over that of TrpRS Urzyme results entirely from coupling between the anticodon-binding domain and an insertion into the Rossmann-fold known as Connecting Peptide 1. We show that this effect is closely related to a long range catalytic effect, in which side chain repacking in a region called the D1 Switch, accounts fully for the entire catalytic contribution of the catalytic Mg(2+) ion. We report intrinsic and higher order interaction effects on the specificity ratio, (kcat/Km)Trp/(kcat/Km)Tyr, of 15 combinatorial mutants from a previous study (Weinreb, V., Li, L., and Carter, C. W., Jr. (2012) Structure 20, 128-138) of the catalytic role of the D1 Switch. Unexpectedly, the same four-way interaction both activates catalytic assist by Mg(2+) ion and contributes -4.4 kcal/mol to the free energy of the specificity ratio. A minimum action path computed for the induced-fit and catalytic conformation changes shows that repacking of the four residues precedes a decrease in the volume of the tryptophan-binding pocket. We suggest that previous efforts to alter amino acid specificities of TrpRS and glutaminyl-tRNA synthetase (GlnRS) by mutagenesis without extensive, modular substitution failed because mutations were incompatible with interdomain motions required for catalysis. PMID:24394410

Weinreb, Violetta; Li, Li; Chandrasekaran, Srinivas Niranj; Koehl, Patrice; Delarue, Marc; Carter, Charles W

2014-02-14

422

Amino acid analysis of spider dragline silk using ¹H NMR.  

PubMed

The amino acid composition of Nephila clavipes dragline silk fiber was determined by conducting ¹H nuclear magnetic resonance (NMR) spectroscopy experiments on acid-hydrolyzed material. N. clavipes dragline silk was found to consist of 43.0±0.6% Gly, 29.3±0.2% Ala, 9.1±0.1% Glx, 4.0±0.1% Leu, 3.3±0.1% Tyr, 3.4±0.2% Ser, 2.7±0.1% Pro, 2.1±0.1% Arg, 1.07±0.05% Asx, 0.96±0.05% Val, 0.48±0.03% Thr, 0.35±0.03% Phe, and 0.28±0.03% Ile. Compared with standard chromatography-based amino acid analysis (AAA), the chemical resolution of NMR allows for an amino acid solution to be characterized without separation and is shown to provide considerably higher precision. This allows for more accurate statistics on the variability of amino acids in spider dragline silk. In general, this ¹H NMR AAA technique is applicable to a large range of proteins and peptides for precise composition characterization, especially when the precise content of a minor component is critical and relatively large amounts of sample are available (microgram to milligram quantities). PMID:23727559

Shi, Xiangyan; Holland, Gregory P; Yarger, Jeffery L

2013-09-15

423

Amino acid grafted chitosan for high performance gene delivery: comparison of amino acid hydrophobicity on vector and polyplex characteristics.  

PubMed

To develop a safe, effective, and biocompatible gene delivery vector, a series of hydrophobic amino acid grafted chitosan (AGC) derivatives were synthesized by carbodiimide mediated coupling reaction. Chemical characterization of AGC polymers was performed by NMR and elemental analysis. AGC polymers demonstrated excellent blood compatibility and cell viability, as evaluated by hemolysis and MTT assay, respectively. AGC polymers could effectively bind and condense plasmid DNA (pDNA) to form polyplexes in the size range of 161-263 nm and possessed net cationic charge. The resultant polyplex showed 3.4-5.4-fold greater cellular uptake and 13-30-fold higher transfection efficiency in HEK 293 cells as compared to unmodified chitosan. Moreover, both cellular uptake and transfection efficiency improved with the increasing amino acid hydrophobicity. Hydrophobic amino acid substitution contributed to the enhance pDNA release at cytosolic pH. These data demonstrate AGC polymers as a promising novel nonviral gene delivery vector. PMID:23301560

Layek, Buddhadev; Singh, Jagdish

2013-02-11

424

Amino Acid Exchange by the Mammary Gland of Lactating Goats when Histidine Limits Milk Production  

E-print Network

Amino Acid Exchange by the Mammary Gland of Lactating Goats when Histidine Limits Milk Production B gland in response to an imposed limitation on His supply for milk production. Lactating goats (n = 4% of energy requirements for milk production. The protein deficiency was alleviated by infusion

Bequette, Brian J.

425

Thermal Stability of Amino Acids in Siliceous Ooze under Alkaline Hydrothermal Condition  

Microsoft Academic Search

Hydrothermal systems have been considered as a suitable environment for the origin and evolution of life on the primitive Earth. For the assessment of this hypothesis, it is required to investigate behaviors of basic biomolecules, such as amino acids (AAs), under hydrothermal condition. Although many experiments on the thermal stability of the AAs in hydrothermal systems have been carried out,

K. Yamaoka; H. Kawahata; L. P. Gupta; M. Ito; H. Masuda

2006-01-01

426

Use of free amino acid composition of shell to estimate age since death of recent molluscs  

Microsoft Academic Search

An understanding of death assemblage formation requires a measurement of time since death of constituent individuals. A new dating technique based on the measurement of the free amino acid content of mollusc shells has been developed which is inexpensive, rapid, and effective in dating time scales of a few decades to a few centuries. Since the breakdown of proteins of

A. M. Logan; E. N. Powell; R. J. Jr. Stanton

1985-01-01

427

Swarming modulatory effects of some amino acids on Proteus strains from Lagos, Nigeria  

Microsoft Academic Search

Swarming motility, a multicellular behaviour characterized by periodic concentric growth on solid media has severally been reported as a constraint in the clinical investigation of mixed- culture infections involving Proteus and as a requirement for virulence. While media are being formulated to restrain swarming in this organism, the roles played by amino acids in the biogenesis of swarming have not

Bamidele A. Iwalokun; Babatunde O. Akinwumi

2002-01-01

428

New Charge-Bearing Amino Acid Residues That Promote ?-Sheet Secondary Structure.  

PubMed

Proteinogenic amino acid residues that promote ?-sheet secondary structure are hydrophobic (e.g., Ile or Val) or only moderately polar (e.g., Thr). The design of peptides intended to display ?-sheet secondary structure in water typically requires one set of residues to ensure conformational stability and an orthogonal set, with charged side chains, to ensure aqueous solubility and discourage self-association. Here we describe new amino acids that manifest substantial ?-sheet propensity, by virtue of ?-branching, and also bear an ionizable group in the side chain. PMID:25393077

Maynard, Stacy J; Almeida, Aaron M; Yoshimi, Yasuharu; Gellman, Samuel H

2014-11-26

429

Random Analysis of Presence and Absence of Twoand Three-Amino-Acid Sequences and Distributions of Amino Acids, Two- and Three-Amino-Acid Sequences in Bovine p53 Protein  

E-print Network

In this study we use five probabilistic procedures to analyse the bovine p53 protein. (1) We count each kind of two-, three- and multi-amino-acid sequences along bovine p53 protein from one terminal to the other and calculate their frequencies and probabilities. (2) We compare the amino-acid sequences in bovine p53 protein with the theoretical amino-acid sequences and determine which theoretical amino-acid sequences are present and absent. (3) We use the random principle to predict the frequencies of presence and absence of amino-acid sequences in bovine p53 protein from its amino acid composition and compare the predicted frequencies with the counted frequencies. (4) We use the random principle to predict the probability that an amino acid follows a preceding amino acid and compare the predicted probabilities with the probabilities occurred in bovine p53 protein. (5) We use the random principle to predict the distributions of amino acids, two- and three-amino-acid sequences in bovine p53 protein and compare the predicted distributions with the measured distributions.

Guang Wu; Shaomin Yan

430

Amino acid composition, available lysine content and in vitro protein digestibility of selected tropical crop seeds.  

PubMed

As the search for alternative sources of food to alleviate hunger continues, this study was undertaken to determine nitrogen and amino acid content, chemical score, protein digestibility corrected amino acid score, available lysine and in vitro digestibility of 8 lesser known, wild tropical seeds, gathered in Nigeria. Results were contrasted with a tropical soybean variety (Glycine max, TGX 1660-15F). The investigated seeds were Millettia thonningii, Gliricidia sepium, Lonchocarpus sericeus, Albizia zygia, Daneillia ogea and Afzella bella from the family of Leguminosae, Diospyros mespiliformis (Ebenaceae) and Entandrophragma angolense (Meliaceae). The crude protein content, based on nitrogen determination, was found to be lower in the wild seeds compared to soybean, which was partly due to the relatively high content of non-protein nitrogen. With reference to amino acid requirement and digestibility in most seed samples, lysine, followed by sulphur amino acids and threonine, were the limiting amino acids. It was concluded, that these less familiar wild seed plants may be used as valuable food or feed complements. However, further investigation is necessary to elucidate potential toxic and antinutritional factors. PMID:9201749

Petzke, K J; Ezeagu, I E; Proll, J; Akinsoyinu, A O; Metges, C C

1997-01-01

431

The metabolic utilization of amino acids: potentials of 14CO2 breath test measurements.  

PubMed

The present paper offers a dual 14CO2 breath test approach to study the metabolic utilization of free amino acids in the body. Using the carboxyl-[14C]isotopomer of an amino acid as the test substrate the percentage recovery of the isotope as 14CO2 reflects which part of the labelled amino acid flux has been decarboxylated. The residual C fragments may flow to total oxidation at least to the level recovered for the universal [14C]isotopomer. In the case that recovery for total oxidation is less than for decarboxylation, part of the [14C]fragments are retained in the body by either exchange or non-oxidative pathways. Utilization of tyrosine and leucine was measured in the post-absorptive phase in adult rats, conditioned on isoenergetic diets containing 210, 75 or 0 g protein/kg. It was shown that the level of dietary protein exerts an influence on both decarboxylation and total oxidation. Although the responses of leucine and tyrosine were not different for total oxidation, there was a difference between the amino acids in their relative rate of decarboxylation. That this dual 14CO2 breath test approach can be used as a tool to evaluate whether the protein and amino acid supply has been adequate to support actual requirements is discussed. PMID:1596496

Schreurs, V V; Boekholt, H A; Koopmanschap, R E; Weijs, P J

1992-03-01

432

Chemical evolution. XXI - The amino acids released on hydrolysis of HCN oligomers  

NASA Technical Reports Server (NTRS)

Major amino acids released by hydrolysis of acidic and basic HCN oligomers are identified by chromatography as Gly, Asp, and diaminosuccinic acid. Smaller amounts of Ala, Ile and alpha-aminoisobutyric acid are also detected. The amino acids released did not change appreciably when the hydrolysis medium was changed from neutral to acidic or basic. The presence of both meso and d, l-diaminosuccinic acids was established by paper chromatography and on an amino acid analyzer.

Ferris, J. P.; Wos, J. D.; Nooner, D. W.; Oro, J.

1974-01-01

433

Zeolitic metal-organic frameworks based on amino acid.  

PubMed

Two enantiomorphic metal-organic frameworks with zeotype SOD topology have been successfully synthesized from enantiopure L-alanine and D-alanine, respectively, which demonstrates the feasibility of fabricating MOFs that integrate the 4-connected zeotype topologies and homochiral nature by the employment of enantiopure amino acids. PMID:25191784

Yang, E; Wang, Lin; Wang, Fei; Lin, Qipu; Kang, Yao; Zhang, Jian

2014-10-01

434

Analysis and survival of amino acids in Martian regolith analogs  

NASA Astrophysics Data System (ADS)

We have investigated the native amino acid composition of two analogs of Martian soil, JSC Mars-1 and Salten Skov. A Mars simulation chamber has been built and used to expose samples of these analogs to temperature and lighting conditions similar to those found at low latitudes on the Martian surface. The effects of the simulated conditions have been examined using high-performance liquid chromatography (HPLC). Exposure to energetic ultraviolet (UV) light in vacuum appears to cause a modest increase in the concentration of certain amino acids within the materials, which is interpreted as resulting from the degradation of microorganisms. The influence of low temperatures shows that the accretion of condensed water on the soils leads to the destruction of amino acids, supporting the idea that reactive chemical processes involving H2O are at work within the Martian soil. We discuss the influence of UV radiation, low temperatures, and gaseous CO2 on the intrinsic amino acid composition of Martian soil analogs and describe, with the help of a simple model, how these studies fit within the framework of life detection on Mars and the practical tasks of choosing and using Martian regolith analogs in planetary research.

Garry, James R. C.; Loes Ten Kate, Inge; Martins, Zita; Nørnberg, Per; Ehrenfreund, Pascale

2006-03-01

435

Amino acids in Antarctica: evolution and fate of marine aerosols  

NASA Astrophysics Data System (ADS)

The chemical composition and size distribution of marine aerosols constitute an important parameter to investigate the latter's impact on global climate change. Amino acids are an important component of organic nitrogen in aerosols and have the ability to activate and act as cloud condensation nuclei, with important effects on the radiation balance. In order to understand which physical and chemical transformations occur during transport processes, aerosol samples were collected during four different Antarctic austral summer campaigns. The mean amino acids concentration detected at the Italian coastal base was 11 pmol m-3. The main components were fine fractions, establishing a local marine source. Once produced on the sea surface, marine aerosols undergo an ageing process, due to various phenomena such as coagulation, or photochemical transformations. This was demonstrated by using the samples collected on the Antarctic plateau, where the background values of amino acids (0.7 and 0.8 pmol m-3) were determined, and concentration enrichment in the coarse particles was observed. Another important source of amino acids in marine aerosols is the presence of biological material, demonstrated through a sampling cruise on the R/V Italica on the Southern Ocean.

Barbaro, E.; Zangrando, R.; Vecchiato, M.; Piazza, R.; Capodaglio, G.; Barbante, C.; Gambaro, A.

2014-06-01

436

Original article Effect of dietary protein and amino acids  

E-print Network

to the rabbits fed the highest protein diet. However, their growth rate was 9% lower. Empty body compositionOriginal article Effect of dietary protein and amino acids on the performance, carcass composition progressively blending a high protein mixture with a low protein mixture, in order to obtain a series of six iso

Boyer, Edmond