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1

Minimizing Amino Acid Catabolism Decreases Amino Acid Requirements1  

Microsoft Academic Search

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

Kirk C. Klasing

2

The amino acid requirements of disease  

Microsoft Academic Search

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

P. J. Reeds; F. Jahoor

2001-01-01

3

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

Microsoft Academic Search

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

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

2009-01-01

4

Parenteral sulfur amino acid requirements in septic infants  

Technology Transfer Automated Retrieval System (TEKTRAN)

To investigate parenteral methionine requirements of critically ill, septic infants, we conducted an investigation involving 12 infants (age 2+/-1 years; weight 13+/-2kg) using the intravenous indicator amino acid oxidation and balance technique. They received a balanced parenteral amino acid formul...

5

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

Microsoft Academic Search

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

Alfred E. Harper

6

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

Microsoft Academic Search

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

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

2002-01-01

7

Brain amino acid requirements and toxicity: the example of leucine.  

PubMed

Glutamic acid is an important excitatory neurotransmitter of the brain. Two key goals of brain amino acid handling are to maintain a very low intrasynaptic concentration of glutamic acid and also to provide the system with precursors from which to synthesize glutamate. The intrasynaptic glutamate level must be kept low to maximize the signal-to-noise ratio upon the release of glutamate from nerve terminals and to minimize the risk of excitotoxicity consequent to excessive glutamatergic stimulation of susceptible neurons. The brain must also provide neurons with a constant supply of glutamate, which both neurons and glia robustly oxidize. The branched-chain amino acids (BCAAs), particularly leucine, play an important role in this regard. Leucine enters the brain from the blood more rapidly than any other amino acid. Astrocytes, which are in close approximation to brain capillaries, probably are the initial site of metabolism of leucine. A mitochondrial branched-chain aminotransferase is very active in these cells. Indeed, from 30 to 50% of all alpha-amino groups of brain glutamate and glutamine are derived from leucine alone. Astrocytes release the cognate ketoacid [alpha-ketoisocaproate (KIC)] to neurons, which have a cytosolic branched-chain aminotransferase that reaminates the KIC to leucine, in the process consuming glutamate and providing a mechanism for the "buffering" of glutamate if concentrations become excessive. In maple syrup urine disease, or a congenital deficiency of branched-chain ketoacid dehydrogenase, the brain concentration of KIC and other branched-chain ketoacids can increase 10- to 20-fold. This leads to a depletion of glutamate and a consequent reduction in the concentration of brain glutamine, aspartate, alanine, and other amino acids. The result is a compromise of energy metabolism because of a failure of the malate-aspartate shuttle and a diminished rate of protein synthesis. PMID:15930465

Yudkoff, Marc; Daikhin, Yevgeny; Nissim, Ilana; Horyn, Oksana; Luhovyy, Bohdan; Luhovyy, Bogdan; Lazarow, Adam; Nissim, Itzhak

2005-06-01

8

Nitrogen Balance of Men Fed Amino Acid Mixtures Based on Rose's Requirements, Egg White Protein, and Serum Free Amino Acid Patterns  

Microsoft Academic Search

Six healthy men were fed formula diets containing crystalline L-amino acids. Ratios of amino acids were designed according to requirements set by W. C. Rose (R); the pattern present in egg white (E); the free amino acids found in serum of fasting men maintained with 75 g egg-white proteins in the diet (S); and an inverse ratio of the serum

LEE ALYCE WELLER; DORIS HOWES GALLOWAY

9

Amino acid and energy requirements for rat hepatocytes in primary culture  

Microsoft Academic Search

Summary  The amino acid and energy requirements of rat hepatocytes in suspension and early culture were investigated. Among a number\\u000a of potential energy substrates tested, pyruvate (20 mM) was found to be most effective in stimulating hepatocytic protein synthesis. Amino acids stimulated protein synthesis both\\u000a as energy substrates and as protein precursors. An amino acid mixture was designed to provide maximal

Per E. Schwarze; Anne E. Solheim; Per O. Seglen

1982-01-01

10

Recent advances in determining protein and amino acid requirements in humans.  

PubMed

During the past 25 years a significant amount of research has been conducted to determine amino acid requirements in humans. This is primarily due to advancements in the application of stable isotopes to examine amino acid requirements. The indicator amino acid oxidation (IAAO) method has emerged as a robust and minimally invasive technique to identify requirements. The IAAO method is based on the concept that when one indispensable dietary amino acid (IDAA) is deficient for protein synthesis, then the excess of all other IDAA, including the indicator amino acid, will be oxidized. With increasing intakes of the limiting amino acid, IAAO will decrease, reflecting increasing incorporation into protein. Once the requirement for the limiting amino acid is met there will be no further change in the indicator oxidation. The IAAO method has been systematically applied to determine most IDAA requirements in adults. The estimates are comparable to the values obtained using the more elaborate 24h-indicator amino acid oxidation and balance (24h-IAAO/IAAB) model. Due to its non-invasive nature the IAAO method has also been used to determine requirements for amino acids in neonates, children and in disease. The IAAO model has recently been applied to determine total protein requirements in humans. The IAAO method is rapid, reliable and has been used to determine amino acid requirements in different species, across the life cycle and in disease. The recent application of IAAO to determine protein requirements in humans is novel and has significant implications for dietary protein intake recommendations globally. PMID:23107531

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

2012-08-01

11

Determining amino acid requirements from repeated observations on indicator amino acid oxidation method by mixed-effect change-point regression models.  

PubMed

In nutrition studies, it is often of primary interest to determine the critical threshold value of some biological quantities. To determine the amino acid requirement, the tracer approach including the indicator amino acid oxidation method is useful for the investigation of human subjects. In this approach, measurements of amino acids other than the test amino acid are often repeatedly carried out with various intakes of the test amino acid. Change-point regression models have often been applied to determine the amino acid requirement. However, within-subject dependence due to repeated measurements has not been sufficiently taken into account. In this paper, we propose a mixed-effect change-point model to estimate the amino acid requirements when utilizing the tracer approach. Inference based on Akaike Information Criteria is introduced to include selection of the optimal model and construction of a confidence interval. Our method can easily be applied with a standard software package, and we found that appropriate accounting for within-subject dependence may lead to a much narrower confidence interval. We recommend application of a mixed-effect change-point regression model to determine the amino acid requirements in studies utilizing the tracer approach. PMID:21980227

Hayamizu, Kohsuke; Kato, Mai; Hattori, Satoshi

2011-07-14

12

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

13

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

Code of Federal Regulations, 2010 CFR

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

2009-07-01

14

Amino acid requirements of fish larvae and post-larvae: new tools and recent findings  

Microsoft Academic Search

This paper reviews methodologies and recent findings in the study of the amino acid (AA) metabolism of fish larvae and post-larvae, in order to better understand the AA requirements. The larval indispensable AA (IAA) profile can be used as index of the IAA requirements. When turbot larvae and live food IAA profiles are compared, the profile of the latter seems

L. E. C. Conceição; H. Grasdalen; I. Rønnestad

2003-01-01

15

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

Microsoft Academic Search

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

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

1986-01-01

16

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

17

Amino acid transport systems required for diazotrophic growth in the cyanobacterium Anabaena sp. strain PCC 7120.  

PubMed Central

Uptake of 16 amino acids by the filamentous, heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 was characterized with regard to kinetic parameters of transport, intracellular accumulation of the transported amino acids, and sensitivity of the transport process to energy metabolism inhibitors. Mutants resistant to certain toxic analogs of some amino acids were isolated that were impaired in amino acid transport. Results obtained in this study, together with those reported previously (A. Herrero and E. Flores, J. Biol. Chem. 265:3931-3935, 1990), suggest that there are at least five amino acid transport systems in strain PCC 7120: one high-affinity, active system for basic amino acids; one low-affinity, passive system for basic amino acids; two high-affinity, active systems with overlapping, but not identical, specificities for neutral amino acids; and one putative system for acidic amino acids. Some of the amino acid transport mutants were impaired in diazotrophic growth. These mutants were unable to develop a normal percentage of heterocysts and normal nitrogenase activity in response to nitrogen stepdown. Putative roles for the amino acid transport systems in uptake of extracellular amino acids, recapture of amino acids that have leaked from the cells, and intercellular transfer of amino acids in the filaments of Anabaena sp. strain PCC 7120 are discussed.

Montesinos, M L; Herrero, A; Flores, E

1995-01-01

18

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

PubMed Central

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

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

2012-01-01

19

Requirement for alanine in the amino acid control of deprivation-induced protein degradation in liver.  

PubMed Central

Protein degradation in liver is actively controlled by a small group of inhibitory amino acids--leucine, tyrosine (or phenylalanine), glutamine, proline, histidine, tryptophan, and methionine. Other evidence, however, suggests that one or more of the remaining 12 noninhibitory amino acids is also required for suppression of proteolysis at normal concentrations. This question was investigated in livers of fed rats perfused in the single-pass mode. The deletion of alanine at normal (1x), but not at 4x or 10x normal, plasma amino acid concentrations evoked a near-maximal acceleration of protein degradation. No other noninhibitory amino acid was effective. Because alanine alone was not directly inhibitory and its omission was not associated with a decrease in inhibitory amino acid pools, alanine was presumed to act as a coregulator in the expression of inhibitory activity. When tested alone, the inhibitory group was as effective as the complete mixture at 0.5x and 4x levels, but it lost its suppressive ability within a narrow zone of concentration centered slightly above 1x. The addition of 1x (0.48 mM) alanine completely restored the inhibition. Pyruvate and lactate could be effectively substituted, but only at concentrations 10-20 times greater than that of alanine. These, together with earlier findings, indicate the existence of a regulatory complex that recognizes specific amino acids and transmits positive and negative signals to proteolytic sites. The results also suggest that alanine can provide an important regulatory link between energy demands and protein degradation.

Poso, A R; Mortimore, G E

1984-01-01

20

D-amino acid-substituted atrial natriuretic peptide analogs reveal novel receptor recognition requirements.  

PubMed

The introduction of D-amino acid residues into peptide hormones has been traditionally utilized in structure-activity studies to probe the conformational requirements of ligand-receptor interactions. A study was undertaken to examine the effect of D-amino acid substitutions into the atrial natriuretic peptide molecule on interactions with distinct subpopulations of specific membrane-associated receptors of bovine aortic smooth muscle cells. Competitive binding analysis revealed that each of 15 synthetic D-amino acid-substituted analogs showed comparable affinities for C-ANP receptors, a class of specific receptors which have been proposed to mediate the sequestration and metabolic clearance of ANP. The relative affinities of all 15 analogs did not differ more than 10-fold. In contrast, the interaction of the ANP analogs with a second receptor pool (B-ANP receptors), which is coupled to the stimulation of particulate guanylate cyclase, varied over a 1000-fold range of potency consistent with expectations for a receptor that displays rigorous conformational specificity. The indiscriminant selectivity of C-ANP receptors for D-amino acid-substituted ANP analogs is unprecedented for hormone receptors involved in biological signal transduction. These results, when coupled with the inability to correlate any direct in vitro biological effect associated with C-ANP receptor occupancy supports the hypothesis that the C-ANP receptor protein is a novel transport protein involved in the metabolic clearance of ANP. PMID:2846552

Scarborough, R M; McEnroe, G A; Arfsten, A; Kang, L L; Schwartz, K; Lewicki, J A

1988-11-15

21

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

Microsoft Academic Search

All living organisms encode the 20 natural amino acid units of polypeptides using a universal scheme of triplet nucleotide\\u000a “codons”. Disparate features of this codon scheme are potentially informative of early molecular evolution: (i) the absence\\u000a of any codons for d-amino acids; (ii) the odd combination of alternate codon patterns for some amino acids; (iii) the confinement of synonymous\\u000a positions

Albert Erives

22

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

Microsoft Academic Search

Summary Following cessation of growth, yeast cells remain viable in a nondividing state for a period of time known as the chronological lifespan (CLS). 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 grown in glucose minimal

Ashley L. Alvers; Laura K. Fishwick; Michael S. Wood; Doreen Hu; Hye S. Chung; William A. Dunn Jr; John P. Aris

2009-01-01

23

Extreme genetic code optimality from a molecular dynamics calculation of amino acid polar requirement  

NASA Astrophysics Data System (ADS)

A molecular dynamics calculation of the amino acid polar requirement is used to score the canonical genetic code. Monte Carlo simulation shows that this computational polar requirement has been optimized by the canonical genetic code, an order of magnitude more than any previously known measure, effectively ruling out a vertical evolution dynamics. The sensitivity of the optimization to the precise metric used in code scoring is consistent with code evolution having proceeded through the communal dynamics of statistical proteins using horizontal gene transfer, as recently proposed. The extreme optimization of the genetic code therefore strongly supports the idea that the genetic code evolved from a communal state of life prior to the last universal common ancestor.

Butler, Thomas; Goldenfeld, Nigel; Mathew, Damien; Luthey-Schulten, Zaida

2009-06-01

24

?-Amino acids  

Microsoft Academic Search

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

V. M. Rodionov; L. V. Antik

1953-01-01

25

Kidney amino acid transport.  

PubMed

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

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

2009-01-28

26

A simple amino acid dose-response method to quantify amino acid requirements of individual meal-fed pigs.  

PubMed

Two experiments were conducted to develop a simplified dose-response technique to estimate the Lys requirement of individual, meal-fed growing pigs. In Exp. 1, we studied adaptation processes that occur during such a dose-response study in meal-fed pigs, and in Exp. 2, we studied the accuracy of this simplified technique to estimate changes in Lys requirement estimates of pigs following changes in energy intake. In Exp. 1, the effect of the Lys supply strategy on the Lys requirement was assessed in 14 barrows fed an increasing [low to high (LH)] or decreasing [high to low (HL)] total Lys supply, with total Lys levels varying from 0.36 to 1.06 g/MJ DE in 7 equidistant steps of 4 d each. Urinary urea and ammonia excretion and whole body N turnover were measured. In Exp. 2, the accuracy of the dose-response technique to determine a shift in Lys requirement was assessed in 20 barrows fed at either 2.2 [low energy (LE)] or 2.7 [high energy (HE)] times the energy requirements for maintenance, with total Lys supply decreasing from 1.10 to 0.37 g Lys/MJ DE in 9 equidistant steps of 3 d each. In Exp. 1, a lower increment in protein synthesis, breakdown, and whole body N turnover with increasing dietary Lys supply was observed in LH pigs than HL pigs (P < 0.01) and the estimated Lys requirement was 0.06 g/MJ DE greater (P = 0.01) in LH pigs than HL pigs. These results indicated that pigs at a decreasing Lys supply strategy require less time for metabolic adaptation to a change in Lys supply than those at an increasing Lys supply. In Exp. 2, the estimated Lys requirement was 2.6 g/d greater (P < 0.001) in HE pigs than LE pigs. The variation in AA requirement estimates between individual pigs was low (4.9% in LH pigs and 3.0% in HL pigs in Exp. 1 and 8.1% in LE pigs and 6.0% in HE pigs in Exp. 2). The present studies indicated that a dose-response technique with a decreasing Lys supply in time and a step length of 3 d with urinary N excretion as response criteria provides a simple, accurate technique to quantitatively estimate a change in AA requirements of individual meal-fed pigs. PMID:23942706

Kampman-van de Hoek, E; Gerrits, W J J; van der Peet-Schwering, C M C; Jansman, A J M; van den Borne, J J G C

2013-08-13

27

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

SciTech Connect

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

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

1991-08-01

28

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

PubMed Central

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

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

1979-01-01

29

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

Microsoft Academic Search

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

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

2007-01-01

30

Amino Acid Sequence Requirements of the Transmembrane and Cytoplasmic Domains of Influenza Virus Hemagglutinin for Viable Membrane Fusion  

Microsoft Academic Search

The amino acid sequence requirements of the transmembrane (TM) domain and cyto- plasmic tail (CT) of the hemagglutinin (HA) of influenza virus in membrane fusion have been investigated. Fusion properties of wild-type HA were compared with those of chimeras consisting of the ectodomain of HA and the TM domain and\\/or CT of poly- immunoglobulin receptor, a nonviral integral membrane protein.

Grigory B. Melikyan; Sasa Lin; Michael G. Roth; Fredric S. Cohen

31

N Terminal 112 amino acid residues are not required for the sialyltransferase activity of Photobacterium damsela ?2,6-sialyltransferase  

Microsoft Academic Search

Photobacterium damsela ?2,6-sialyltransferase was cloned as N- and C- His-tagged fusion proteins with different lengths (16–497 aa or 113–497 aa). Expression and activity assays indicated that\\u000a the N-terminal 112 amino acid residues of the protein were not required for its ?2,6-sialyltransferase activity. Among four truncated\\u000a forms tested, N-His-tagged ?15Pd2,6ST(N) containing 16–497 amino acid residues had the highest expression level. Similar to the

Mingchi Sun; Yanhong Li; Harshal A. Chokhawala; Ryan Henning; Xi Chen

2008-01-01

32

Dietary requirements of "nutritionally non-essential amino acids" by animals and humans.  

PubMed

Amino acids are necessary for the survival, growth, development, reproduction and health of all organisms. They were traditionally classified as nutritionally essential or non-essential for mammals, birds and fish based on nitrogen balance or growth. It was assumed that all "non-essential amino acids (NEAA)" were synthesized sufficiently in the body to meet the needs for maximal growth and health. However, there has been no compelling experimental evidence to support this assumption over the past century. NEAA (e.g., glutamine, glutamate, proline, glycine and arginine) play important roles in regulating gene expression, cell signaling, antioxidative responses, neurotransmission, and immunity. Additionally, glutamate, glutamine and aspartate are major metabolic fuels for the small intestine to maintain its digestive function and protect its mucosal integrity. Therefore, based on new research findings, NEAA should be taken into consideration in revising the classical "ideal protein" concept and formulating balanced diets to improve protein accretion, food efficiency, and health in animals and humans. PMID:23247926

Wu, Guoyao; Wu, Zhenlong; Dai, Zhaolai; Yang, Ying; Wang, Weiwei; Liu, Chuang; Wang, Bin; Wang, Junjun; Yin, Yulong

2012-12-18

33

EBNA2 Amino Acids 3 to 30 Are Required for Induction of LMP-1 and Immortalization Maintenance  

PubMed Central

Epstein-Barr virus (EBV) nuclear antigen 2 (EBNA2), a direct transcriptional activator of viral and cellular genes, is required for EBV-induced B-cell transformation. The functional role of conserved regions within the amino terminus of the protein preceding the poly-proline region has yet to be fully characterized. Thus, we tested whether the EBNA2 amino-terminal 30 amino acid residues, containing evolutionarily conserved region 1, are required for stimulating viral and cellular gene expression necessary for B-cell transformation in a viral transcomplementation assay. We found that these residues are required for its ability to induce LMP-1 expression in lymphoblastoid cell lines (LCLs), to stimulate LMP-1 promoter reporter plasmids in transient-cotransfection assays, and to rescue LCL growth following inactivation of endogenous wild-type EBNA2 protein. Deletion of amino acid residues 3 to 30 also impaired its ability to self-associate in coimmunoprecipitation assays. These data indicate that EBNA2 residues 3 to 30 comprise an essential domain required for induction of LMP-1 expression and, consequently, for maintenance of the immortalized phenotype of LCLs. The ability to self-associate into dimers or multimers conferred by this domain may be an important mechanism for these effects.

Gordadze, Alexey V.; Onunwor, Chisaroka W.; Peng, RongSheng; Poston, David; Kremmer, Elisabeth; Ling, Paul D.

2004-01-01

34

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

35

An aspartic acid at amino acid 108 is required to rescue infectious virus after transfection of a poliovirus cDNA containing a CGDD but not SGDD amino acid motif in 3Dpol.  

PubMed Central

The poliovirus RNA-dependent RNA polymerase (3Dpol) contains a region of homology centered around the amino acid motif YGDD (amino acids 326 to 329), which has been postulated to be involved in the catalytic activity of the enzyme. Previous studies from this laboratory have used oligonucleotide site-directed mutagenesis to substitute the tyrosine amino acid at this motif with other amino acids (S. A. Jablonski and C. D. Morrow, J. Virol. 67:373-381, 1993). The viruses recovered with 3Dpol genes with a methionine mutation also contained a second mutation at amino acid 108 resulting in a glutamic acid-to-aspartic acid change (3D-E-108 to 3D-D-108) in the poliovirus RNA polymerase. On the basis of these results, we suggested that the amino acid at position 108 might interact with the YGDD region of the poliovirus polymerase. To further investigate this possibility, we have constructed a series of constructs in which the poliovirus RNA polymerases contained a mutation at amino acid 108 (3D-E-108 to 3D-D-108) as well as a mutation in which the tyrosine amino acid (3D-Y-326) was substituted with cysteine (3D-C-326) or serine (3D-S-326). The mutant 3Dpol polymerases were expressed in Escherichia coli, and in vitro enzyme activity was analyzed. Enzymes containing the 3D-D-108 mutation with the wild-type amino acid (3D-Y-326) demonstrated in vitro enzyme activity similar to that of the wild-type enzyme containing 3D-E-108. In contrast, enzymes with the 3D-C-326 or 3D-S-326 mutation had less in vitro activity than the wild type. The inclusion of the second mutation at amino acid 3D-D-108 did not significantly affect the in vitro activity of the polymerases containing 3D-C-326 or 3D-S-326 mutation. Transfections of poliovirus cDNAs containing the substitution at amino acid 326 with or without the second mutation at amino acid 108 were performed. Consistent with previous findings, we found that transfection of poliovirus cDNAs containing the 3D-C-326 or 3D-S-326 mutation in 3Dpol did not result in the production of virus. Surprisingly, transfection of the poliovirus cDNAs containing the 3D-D-108/C-326 double mutation, but not the 3D-D-108/S-326 mutation, resulted in the production of virus. The virus obtained from transfection of polio-virus cDNAs containing 3D-D-108/C-326 mutation replicated with kinetics similar to that of the wild-type virus. RNA sequence analysis of the region of the 3Dpol containing the 3D-C-326 mutation revealed that the codon for cysteine (UGC) reverted to the codon for tyrosine (UAC). The results of these studies establish that under the appropriate conditions, poliovirus has the capacity to revert mutations within the YGDD amino acid motif of the poliovirus 3Dpol gene and further strengthen the idea that interaction between amino acid 108 and the YGDD region of 3Dpol is required for viral replication.

Walker, D E; McPherson, D; Jablonski, S A; McPherson, S; Morrow, C D

1995-01-01

36

Amino acids: Analytical aspects  

Microsoft Academic Search

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

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

2001-01-01

37

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

38

A putative branched-chain-amino-acid transaminase gene required for HC-toxin biosynthesis and pathogenicity in Cochliobolus carbonum.  

PubMed

The cyclic tetrapeptide HC-toxin is required for pathogenicity of the filamentous fungus Cochliobolus carbonum on maize. HC-toxin production is controlled by a complex locus, TOX2. The isolation and characterization of a new gene of the TOX2 locus, TOXF, is reported. It is shown that TOXF is specifically required for HC-toxin production and pathogenicity. It is present as two or three copies in all HC-toxin-producing (Tox2+) isolates and is absent in toxin-non-producing strains. The deduced amino acid sequence of TOXF has moderate homology to many known or putative branched-chain-amino-acid transaminases from various species. A strain of C. carbonum with all copies of TOXF disrupted grew normally but lost HC-toxin production and pathogenicity. It is proposed that TOXF has a biosynthetic role in HC-toxin synthesis, perhaps to aminate a precursor of Aeo (2-amino-9,10-epoxi-8-oxodecanoic acid). PMID:10627051

Cheng, Y Q; Ahn, J H; Walton, J D

1999-12-01

39

Requirement of N-terminal amino acid residues of gp41 for human immunodeficiency virus type 1-mediated cell fusion.  

PubMed Central

An expression vector was designed to test the structural requirements of the gp41 N terminus for human immunodeficiency virus type 1-induced membrane fusion. Mutations in the region coding for the N terminus of gp41 were found to disrupt glycoprotein expression because of deleterious effects on the Rev-responsive element (RRE). Insertion of an additional RRE in the 3'-noncoding sequence of env made possible efficient glycoprotein expression, irrespective of the mutations introduced into the RRE in the natural location. This permitted the insertion of the unique restriction site SpeI within the N-terminal sequences of gp41, allowing convenient and efficient mutation of the gp41 N terminus by using double-stranded synthetic oligonucleotides. Mutants with deletions of 1 to 7 amino acids of the N terminus were constructed. Expression and cleavage of all mutants were confirmed by Western immunoblot analysis with anti-gp41 antibodies. The capability of mutants to induce membrane fusion was monitored following transfection of HeLa-T4+ cell lines with wild-type and mutant expression vectors by electroporation and microinjection. The efficiency of cell-fusing activity decreased drastically with deletion of 3 and 4 amino acids and was completely lost with deletion of 5 amino acids. Cotransfection of the parent and mutant expression vectors resulted in reduced cell-fusing activity. The extent of this dominant interference by mutant glycoprotein paralleled the decrease in cell-fusing activity of the mutants alone. This suggests the existence of a specific N-terminal structure required for fusing activity. However, there does not appear to be a stringent requirement for the precise length of the N terminus. This finding is supported by the length variation of this region among natural human immunodeficiency virus type 1 isolates and is in contrast to the apparent stringency in the length of analogous N-terminal structures of influenza A virus and paramyxovirus fusion glycoproteins.

Schaal, H; Klein, M; Gehrmann, P; Adams, O; Scheid, A

1995-01-01

40

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, A

2012-06-06

41

Multiple GCD genes required for repression of GCN4, a transcriptional activator of amino acid biosynthetic genes in Saccharomyces cerevisiae.  

PubMed Central

GCN4 encodes a positive regulator of multiple unlinked genes encoding amino acid biosynthetic enzymes in Saccharomyces cerevisiae. Expression of GCN4 is coupled to amino acid availability by a control mechanism involving GCD1 as a negative effector and GCN1, GCN2, and GCN3 as positive effectors of GCN4 expression. We used reversion of a gcn2 gcn3 double mutation to isolate new alleles of GCD1 and mutations in four additional GCD genes which we designate GCD10, GCD11, GCD12, and GCD13. All of the mutations lead to constitutive derepression of HIS4 transcription in the absence of the GCN2+ and GCN3+ alleles. By contrast, the gcd mutations require the wild-type GCN4 allele for their derepressing effect, suggesting that each acts by influencing the level of GCN4 activity in the cell. Consistent with this interpretation, mutations in each GCD gene lead to constitutive derepression of a GCN4::lacZ gene fusion. Thus, at least five gene products are required to maintain the normal repressed level of GCN4 expression in nonstarvation conditions. Interestingly, the gcd mutations are pleiotropic and also affect growth rate in nonstarvation conditions. In addition, certain alleles lead to a loss of M double-stranded RNA required for the killer phenotype. This pleiotropy suggests that the GCD gene products contribute to an essential cellular function, in addition to, or in conjunction with, their role in GCN4 regulation. Images

Harashima, S; Hinnebusch, A G

1986-01-01

42

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

PubMed Central

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

2012-01-01

43

Modeling mammary amino acid metabolism  

Microsoft Academic Search

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

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

2001-01-01

44

Transformation of some hydroxy amino acids to other amino acids.  

PubMed

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

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

1975-10-01

45

Review of advances in metabolic bioavailability of amino acids  

Microsoft Academic Search

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

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

2010-01-01

46

Natural amino acids do not require their native tRNAs for efficient selection by the ribosome  

PubMed Central

The involvement of tRNA structural elements beyond the anticodon in aminoacyl-tRNA (aa-tRNA) selection by the ribosome has revealed that substrate recognition is considerably more complex than originally envisioned in the adaptor hypothesis. By combining recent breakthroughs in aa-tRNA synthesis and mechanistic and structural studies of protein synthesis, we ask if aa-tRNA recognition further extends to the amino acid, thereby explaining various translation disorders exhibited by misacylated tRNAs. Contrary to expectation, we find that natural amino acids misacylated onto natural, but non-native tRNAs are selected with efficiencies very similar to those of their correctly-acylated counterparts. Despite this, small, but reproducible differences in selection indeed demonstrate that the translational machinery is sensitive to the amino acid/tRNA pairing. These results suggest that either the ribosome is an exquisite sensor of natural versus unnatural amino acid/tRNA pairings and/or that aa-tRNA selection is not the primary step governing the amino acid specificity of the ribosome.

Effraim, Philip R.; Wang, Jiangning; Englander, Michael T.; Avins, Josh

2010-01-01

47

Understanding conserved amino acids in proteins  

NASA Astrophysics Data System (ADS)

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

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

2002-11-01

48

Genome-wide siRNA screen reveals amino acid starvation-induced autophagy requires SCOC and WAC.  

PubMed

Autophagy is a catabolic process by which cytoplasmic components are sequestered and transported by autophagosomes to lysosomes for degradation, enabling recycling of these components and providing cells with amino acids during starvation. It is a highly regulated process and its deregulation contributes to multiple diseases. Despite its importance in cell homeostasis, autophagy is not fully understood. To find new proteins that modulate starvation-induced autophagy, we performed a genome-wide siRNA screen in a stable human cell line expressing GFP-LC3, the marker-protein for autophagosomes. Using stringent validation criteria, our screen identified nine novel autophagy regulators. Among the hits required for autophagosome formation are SCOC (short coiled-coil protein), a Golgi protein, which interacts with fasciculation and elongation protein zeta 1 (FEZ1), an ULK1-binding protein. SCOC forms a starvation-sensitive trimeric complex with UVRAG (UV radiation resistance associated gene) and FEZ1 and may regulate ULK1 and Beclin 1 complex activities. A second candidate WAC is required for starvation-induced autophagy but also acts as a potential negative regulator of the ubiquitin-proteasome system. The identification of these novel regulatory proteins with diverse functions in autophagy contributes towards a fuller understanding of autophagosome formation. PMID:22354037

McKnight, Nicole C; Jefferies, Harold B J; Alemu, Endalkachew A; Saunders, Rebecca E; Howell, Michael; Johansen, Terje; Tooze, Sharon A

2012-02-21

49

Amino acids in Arctic aerosols  

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

50

Synthesis of amino acids  

DOEpatents

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

Davis, J.W. Jr.

1979-09-21

51

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.

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

2012-01-01

52

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

PubMed

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

2012-12-20

53

Amino Acid Sequence Requirements at Residues 69 and 238 for the SME1  Lactamase To Confer Resistance to  Lactam Antibiotics  

Microsoft Academic Search

Carbapenem antibiotics have been used to counteract resistant strains of bacteria harboring -lactamases and extended-spectrum -lactamases. Four enzymes from the class A group of -lactamases, NMC-A, IMI-1, SME-1, and KPC-1, efficiently hydrolyze carbapenem antibiotics. Sequence comparisons and structural infor- mation indicate that cysteines at amino acid residues 69 and 238, which are conserved in all four of these enzymes, form

Fahd K. Majiduddin; Timothy Palzkill

2003-01-01

54

Daily methionine requirements of healthy Indian men, measured by a 24-h indicator amino acid oxidation and balance technique1-3  

Microsoft Academic Search

Background: The 1985 FAO\\/WHO\\/UNU upper requirement for the sulfur-containing amino acids in healthy adults, which was set at 13 mg · kg? 1 ·d ? 1, is based on nitrogen balance studies in West- ern subjects. Short-term tracer-based studies also estimated a mean requirement of 13 mg · kg? 1 ·d ? 1, but whether this estimate is applicable to

Anura V Kurpad; Meredith M Regan; Sureka Varalakshmi; Jahnavi Vasudevan; Justin Gnanou; Tony Raj; Vernon R Young

55

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

56

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

57

The Essential Amino Acids of 'Mytilus californianus'.  

National Technical Information Service (NTIS)

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

C. Harrison

1975-01-01

58

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

59

Specific binding of HIV-1 nucleocapsid protein to PSI RNA in vitro requires N-terminal zinc finger and flanking basic amino acid residues.  

PubMed Central

The nucleocapsid (NC) protein of human immunodeficiency virus HIV-1 (NCp7) is responsible for packaging the viral RNA by recognizing a packaging site (PSI) on the viral RNA genome. NCp7 is a molecule of 55 amino acids containing two zinc fingers, with only the first one being highly conserved among retroviruses. The first zinc finger is flanked by two basic amino acid clusters. Here we demonstrate that chemically synthesized NCp7 specifically binds to viral RNA containing the PSI using competitive filter binding assays. Deletion of the PSI from the RNA abrogates this effect. The 35 N-terminal amino acids of NCp7, comprising the first zinc finger, are sufficient for specific RNA binding. Chemically synthesized mutants of the first zinc finger demonstrate that the amino acid residues C-C-C/H-C/H are required for specific RNA binding and zinc coordination. Amino acid residues F16 and T24, but not K20, E21 and G22, located within this zinc finger, are essential for specific RNA binding as well. The second zinc finger cannot replace the first one. Furthermore, mutations in the basic amino acid residues flanking the first zinc finger demonstrate that R3, 7, 10, 29 and 32 but not K11, 14, 33 and 34 are also essential for specific binding. Specific binding to viral RNA is also observed with recombinant NCp15 and Pr55Gag. The results demonstrate for the first time specific interaction of a retroviral NC protein with its PSI RNA in vitro. Images

Dannull, J; Surovoy, A; Jung, G; Moelling, K

1994-01-01

60

Deprivation of protein or amino acid induces C/EBP? synthesis and binding to amino acid response elements, but its action is not an absolute requirement for enhanced transcription  

PubMed Central

A nutrient stress signalling pathway is triggered in response to protein or amino acid deprivation, namely the AAR (amino acid response), and previous studies have shown that C/EBP? (CCAAT/enhancer-binding protein ?) expression is up-regulated following activation of the AAR. DNA-binding studies, both in vitro and in vivo, have revealed increased C/EBP? association with AARE (AAR element) sequences in AAR target genes, but its role is still unresolved. The present results show that in HepG2 human hepatoma cells, the total amount of C/EBP? protein, both the activating [LAP* and LAP (liver-enriched activating protein)] and inhibitory [LIP (liver-enriched inhibitory)] isoforms, was increased in histidine-deprived cells. Immunoblotting of subcellular fractions and immunostaining revealed that most of the C/EBP? was located in the nucleus. Consistent with these observations, amino acid limitation caused an increase in C/EBP? DNA-binding activity in nuclear extracts and chromatin immunoprecipitation revealed an increase in C/EBP? binding to the AARE region in vivo, but at a time when transcription from the target gene was declining. A constant fraction of the basal and increased C/EBP? protein was phosphorylated on Thr235 and the phospho-C/EBP? did bind to an AARE. Induction of AARE-enhanced transcription was slightly greater in C/EBP?-deficient MEFs (mouse embryonic fibroblasts) or C/EBP? siRNA (small interfering RNA)-treated HepG2 cells compared with the corresponding control cells. Transient expression of LAP*, LAP or LIP in C/EBP?-deficient fibroblasts caused suppression of increased transcription from an AARE-driven reporter gene. Collectively, the results demonstrate that C/EBP? is not required for transcriptional activation by the AAR pathway but, when present, acts in concert with ATF3 (activating transcription factor 3) to suppress transcription during the latter stages of the response.

Thiaville, Michelle M.; Dudenhausen, Elizabeth E.; Zhong, Can; Pan, Yuan-Xiang; Kilberg, Michael S.

2013-01-01

61

Protein and amino acid nutrition of lactating dairy cattle.  

PubMed

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

Chalupa, W; Sniffen, C J

1991-07-01

62

N-terminal 112 amino acid residues are not required for the sialyltransferase activity of Photobacterium damsela ? 2,6-sialyltransferase  

PubMed Central

Photobacterium damsela ?2,6-sialyltransferase was cloned as N- and C- His-tagged fusion proteins with different lengths (16–497 aa or 113–497 aa). Expression and activity assays indicated that the N-terminal 112 amino acid residues of the protein were not required for its ?2,6-sialyltransferase activity. Among four truncated forms tested, N-His-tagged ?15Pd2,6ST(N) containing 16–497 amino acid residues had the highest expression level. Similar to the ?15Pd2,6ST(N), the shorter ?112Pd2,6ST(N) was active in a wide pH range of 7.5–10.0. A divalent metal ion was not required for the sialyltransferase activity, and the addition of EDTA and dithiothreitol did not affect the activity significantly.

Sun, Mingchi; Li, Yanhong; Chokhawala, Harshal A.; Henning, Ryan; Chen, Xi

2008-01-01

63

Structurally Conserved Amino Acid W501 Is Required for RNA Helicase Activity but Is Not Essential for DNA Helicase Activity of Hepatitis C Virus NS3 Protein  

Microsoft Academic Search

Hepatitis C virus (HCV) is a positive-strand RNA virus that encodes a helicase required for viral replication. Although HCV does not replicate through a DNA intermediate, HCV helicase unwinds both RNA and DNA duplexes. An X-ray crystal structure of the HCV helicase complexed with (dU)8 has been solved, and the substrate-amino acids interactions within the catalytic pocket were shown. Among

Jong Won Kim; M. Y. Seo; A. Shelat; C. S. Kim; T. W. Kwon; H.-h. Lu; D. T. Moustakas; J. Sun; J. H. Han

2003-01-01

64

Mutagenesis identifies the critical regions and amino acid residues of suid herpesvirus 1 DNA-binding protein required for DNA binding and strand invasion.  

PubMed

Herpesviral DNA-binding protein (DBP) is a unique protein involved in viral DNA replication and genomic recombination. It binds and stabilizes the single-stranded DNA. It also forms the D-loops and promotes the strand invasion. To identify the functional regions and amino acid residues required for DNA binding and D-loop formation, we characterized several DBP mutants of suid herpesvirus 1 (SuHV-1). Acetic anhydride modification assay showed that lysine residues were critical for DNA binding and D-loop formation. Replacement of highly conserved lysine residues with alanine revealed that Lys-756 and Lys-970 were critical for DNA binding, while Lys-161 participated in DNA binding and D-loop formation. Analysis of nested deleted mutants showed that N-terminal 201 amino acid residues and C-terminal 305 amino acid residues were required for D-loop formation and DNA binding, respectively. In conclusion, these findings suggested that SuHV-1 DBP contained critical regions for DNA binding and D-loop formation, and Lys-161, Lys-756, and Lys-970 were required for DNA binding or D-loop formation. PMID:19100791

Wu, Shih-Lu; Li, Chia-Cheng; Ho, Tin-Yun; Hsiang, Chien-Yun

2009-01-04

65

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

Microsoft Academic Search

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

James C. Wesenberg; Jacqueline E. Walpole

1980-01-01

66

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

National Technical Information Service (NTIS)

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

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

1964-01-01

67

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

PubMed Central

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

Rodriguez, Kenny R.

2013-01-01

68

An amino acid transporter involved in gastric acid secretion.  

PubMed

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

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

2005-11-25

69

Disorders of Amino Acid Metabolism  

MedlinePLUS

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

70

Characterization of a Pseudomonas putida ABC transporter (AatJMQP) required for acidic amino acid uptake: biochemical properties and regulation by the Aau two-component system.  

PubMed

We describe an ATP-binding cassette (ABC) transporter in Pseudomonas putida KT2440 that mediates the uptake of glutamate and aspartate. The system (AatJMQP, for acidic amino acid transport) is encoded by an operon involving genes PP1071-PP1068. A deletion mutant with inactivated solute-binding protein (KTaatJ) failed to grow on Glu and Gln as sole sources of carbon and nitrogen, while a mutant lacking a functional nucleotide-binding domain (KTaatP) was able to adapt to growth on Glu after an extended lag phase. Uptake of Glu and Asp by either mutant was greatly impaired at both low and high amino acid concentrations. The purified solute-binding protein AatJ exhibited high affinity towards Glu and Asp (K(d)=0.4 and 1.3 muM, respectively), while Gln and Asn as well as dicarboxylates (succinate and fumarate) were bound with much lower affinity. We further show that the expression of AatJMQP is controlled by the sigma(54)-dependent two-component system AauRS. Binding of the response regulator AauR to the aat promoter was examined by gel mobility shift assays and DNase I footprinting. By in silico screening, the AauR-binding motif (the inverted repeat TTCGGNNNNCCGAA) was detected in further P. putida KT2440 genes with established or putative functions in acidic amino acid utilization, and also occurred in other pseudomonads. The products of these AauR-responsive genes include the H(+)/Glu symporter GltP, a periplasmic glutaminase/asparaginase, AnsB, and phosphoenolpyruvate synthase (PpsA), a key enzyme of gluconeogenesis in Gram-negative bacteria. Based on these findings, we propose that AauR is a central regulator of acidic amino acid uptake and metabolism in pseudomonads. PMID:18310026

Singh, Birendra; Röhm, Klaus-Heinrich

2008-03-01

71

Amino Acids and the Mitochondria  

Microsoft Academic Search

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

Nicola King

72

Hydrothermal synthesis of amino acids  

SciTech Connect

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

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

1994-05-01

73

Amino acid auxotrophs from protoplast cultures of Nicotiana plumbaginifolia , Viviani  

Microsoft Academic Search

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

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

1985-01-01

74

Functional interactions between the retinoblastoma (Rb) protein and Sp-family members: superactivation by Rb requires amino acids necessary for growth suppression.  

PubMed Central

The transient expression of the retinoblastoma protein (Rb) regulates the transcription of a variety of growth-control genes, including c-fos, c-myc, and the gene for transforming growth factor beta 1 via discrete promoter sequences termed retinoblastoma control elements (RCE). Previous analyses have shown that Sp1 is one of three RCE-binding proteins identified in nuclear extracts and that Rb functionally interacts with Sp1 in vivo, resulting in the "superactivation" of Sp1-mediated transcription. By immunochemical and biochemical criteria, we report that an Sp1-related transcription factor, Sp3, is a second RCE-binding protein. Furthermore, in transient cotransfection assays, we report that Rb "superactivates" Sp3-mediated RCE-dependent transcription in vivo and that levels of superactivation are dependent on the trans-activator (Sp1 or Sp3) studied. Using expression vectors carrying mutated Rb cDNAs, we have identified two portions of Rb required for superactivation: (i) a portion of the Rb "pocket" (amino acids 614-839) previously determined to be required for physical interactions between Rb and transcription factors such as E2F-1 and (ii) a novel amino-terminal region (amino acids 140-202). Since both of these regions of Rb are targets of mutation in human tumors, our data suggest that superactivation of Sp1/Sp3 may play a role in Rb-mediated growth suppression and/or the induction of differentiation. Images Fig. 1 Fig. 2

Udvadia, A J; Templeton, D J; Horowitz, J M

1995-01-01

75

Amino acids and cell regulation.  

PubMed Central

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

Forster, R. P.; Goldstein, L.

1979-01-01

76

Transport and metabolism of amino acids in placenta  

Microsoft Academic Search

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

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

2002-01-01

77

Digestible amino acids for poultry and swine  

Microsoft Academic Search

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

Carl M. Parsons

1996-01-01

78

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

79

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

PubMed

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

Kino, Kuniki

2010-11-01

80

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

Microsoft Academic Search

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

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

2007-01-01

81

Available versus digestible amino acids - new stable isotope methods.  

PubMed

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

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

2012-08-01

82

Dietary Management of Stress Using Amino Acid Supplements  

Microsoft Academic Search

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

Miro Smriga; Kunio Torii

83

Cheese flavour formation by amino acid catabolism  

Microsoft Academic Search

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

Mireille Yvon; Liesbeth Rijnen

2001-01-01

84

Amino acids and gut function  

Microsoft Academic Search

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

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

2009-01-01

85

Stereoselective ribosylation of amino acids.  

PubMed

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

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

2013-04-24

86

Alicyclic ?-amino acids in Medicinal Chemistry  

Microsoft Academic Search

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

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

2005-01-01

87

Substrate specificity of the amino acid transporter PAT1  

Microsoft Academic Search

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

L. Metzner; K. Neubert; M. Brandsch

2006-01-01

88

21 CFR 172.320 - Amino acids.  

Code of Federal Regulations, 2010 CFR

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

2009-04-01

89

21 CFR 172.320 - Amino acids.  

Code of Federal Regulations, 2010 CFR

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

2010-01-01

90

Alteration of GyrA Amino Acid Required for Ciprofloxacin Resistance in Klebsiella pneumoniae Isolates in China  

Microsoft Academic Search

Resistance to ciprofloxacin was detected in 111 (48.1%) isolates of Klebsiella pneumoniae from China. GyrA alterations were identified in the ciprofloxacin-resistant and ciprofloxacin-susceptible isolates. The results, including previously published data, indicate that the single substitution Ser833Ile and three types of double mutations at Ser83 and Asp87 were required for ciprofloxacin resistance (P < 0.05). Resistance to fluoroquinolones is increasing in

Yingmei Fu; Lishuang Guo; Yan Xu; Wenli Zhang; Jiaao Gu; Jianfeng Xu; Xiaobei Chen; Yuehui Zhao; Jiayu Ma; Xinghan Liu; Fengmin Zhang

2008-01-01

91

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

Microsoft Academic Search

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

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

2004-01-01

92

Amino Acid Composition of Germinating Cotton Seeds  

PubMed Central

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

Elmore, C. Dennis; King, Earl E.

1978-01-01

93

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.

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

1998-01-01

94

Identification of amino acid sequence motifs in desmocollin, a desmosomal glycoprotein, that are required for plakoglobin binding and plaque formation.  

PubMed

By transfecting epithelial cells with gene constructs encoding chimeric proteins of the transmembrane part of the gap junction protein connexin 32 in combination with various segments of the cytoplasmic part of the desmosomal cadherin desmocollin 1a, we have determined that a relatively short sequence element is necessary for the formation of desmosome-like plaques and for the specific anchorage of bundles of intermediate-sized filaments (IFs). Deletion of as little as the carboxyl-terminal 37 aa resulted in a lack of IF anchorage and binding of the plaque protein plakoglobin, as shown by immunolocalization and immunoprecipitation experiments. In addition, we show that the sequence requirements for the recruitment of desmoplakin, another desmosomal plaque protein, differ and that a short (10 aa) segment of the desmocollin 1a tail, located close to the plasma membrane, is also required for the binding of plakoglobin, as well as of desmoplakin, and also for IF anchorage. The importance of the carboxyl-terminal domain, homologous in diverse types of cadherins, is emphasized, as it must harbor, in a mutually exclusive pattern, the information for assembly of the IF-anchoring desmosomal plaque in desmocollins and for formation of the alpha-/beta-catenin- and vinculin-containing, actin filament-anchoring plaque in E- and N-cadherin. PMID:7971964

Troyanovsky, S M; Troyanovsky, R B; Eshkind, L G; Leube, R E; Franke, W W

1994-11-01

95

Evolutionary patterns of amino acid substitutions in 12 Drosophila genomes  

Microsoft Academic Search

BACKGROUND: Harnessing vast amounts of genomic data in phylogenetic context stemming from massive sequencing of multiple closely related genomes requires new tools and approaches. We present a tool for the genome-wide analysis of frequencies and patterns of amino acid substitutions in multiple alignments of genes’ coding regions, and a database of amino acid substitutions in the phylogeny of 12 Drosophila

Lev Y Yampolsky; Michael A Bouzinier

2010-01-01

96

Sugar amino acids in designing new molecules.  

PubMed

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

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

2005-03-01

97

The Seven Amino Acids (547-553) of Rat Glucocorticoid Receptor Required for Steroid and Hsp90 Binding Contain a Functionally Independent LXXLL Motif That Is Critical for Steroid Binding  

Microsoft Academic Search

Hsp90 association with glucocorticoid receptors (GRs) is required for steroid binding. We recently reported that seven amino acids (547-553) overlapping the amino- terminal end of the rat GR ligand-binding domain are necessary for hsp90 binding, and consequently steroid binding. The role of a LXXLL motif at the COOH termi- nus of this sequence has now been analyzed by deter- mining

Georgia Giannoukos; Adam M. Silverstein; William B. Pratt; S. Stoney

1999-01-01

98

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

Microsoft Academic Search

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

P. E. V. Williams

1995-01-01

99

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

Microsoft Academic Search

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

A. M. Skelley; J. R. Scherer; A. D. Aubrey; R. H. Ivester; P. Ehrenfreund; F. J. Grunthaner; J. L. Bada; R. A. Mathies

2004-01-01

100

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

Microsoft Academic Search

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

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

2003-01-01

101

Amino acid composition in Isoparorchis hypselobagri  

Microsoft Academic Search

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

Meenakshi Srivastava; S. P. Gupta

1976-01-01

102

Amino acid regulation of TOR complex 1  

PubMed Central

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

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

2009-01-01

103

Characterization of Amino Acid Efflux from Isolated Soybean Cells 1  

PubMed Central

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

Secor, Jacob; Schrader, Larry E.

1984-01-01

104

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

PubMed

An 8-week feeding trial was conducted to determine the dietary tryptophan requirement of fingerling Indian catfish, Heteropneustes fossilis (6.10 ± 1.15 cm, 4.44 ± 0.50 g). Six isonitrogenous (40 g 100 g?¹) and isoenergetic (17.90 kJ g?¹) amino acid test diets were formulated with gradation of 0.1 g 100 g?¹ containing graded levels of L-tryptophan (0.04-0.54 g 100 g?¹, dry diet). Fish were stocked in triplicate groups, in 75-L circular trough with flow-through system and fed experimental diets at 4% BW/day twice daily. Maximum live weight gain (258%), best feed conversion ratio (FCR) (1.54) and protein efficiency ratio (PER) (1.62) were obtained in fish fed diet containing 0.34 g 100 g?¹ tryptophan. However, quadratic regression analysis of weight gain, FCR, PER and body protein deposition (BPD) data indicated requirements for dietary tryptophan at 0.37, 0.33, 0.32 and 0.33 g 100 g?¹ of dry diet, respectively. Significantly (P < 0.05) higher body protein, minimum moisture and intermediate fat contents were recorded at 0.34 g 100 g?¹ dietary tryptophan diet. Ash content was not significantly different (P > 0.05) among treatments except for diets 0.04 and 0.14 g 100 g?¹. Excellent somatic and haematological indices values were obtained at the requirement level. Based on above results, it is recommended that the diet for H. fossilis should contain tryptophan at 0.32 g 100 g?¹, dry diet, corresponding to 0.80 g 100 g?¹ dietary protein for optimum growth and efficient feed utilization. PMID:22437368

Ahmed, Imtiaz

2012-03-22

105

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

PubMed Central

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

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

1972-01-01

106

Astroglial amino acid-based transmitter receptors.  

PubMed

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

Parpura, Vladimir; Verkhratsky, Alexei

2013-01-26

107

METABOLISM OF ?-AMINO ACIDS V.  

PubMed Central

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

Hardman, John K.; Stadtman, Thressa C.

1963-01-01

108

Molecular Ontology of Amino Acid Transport  

Microsoft Academic Search

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

Dmitri Y. Boudko

109

Characteristics of amino acid uptake in barley  

Microsoft Academic Search

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

Sandra Jämtgård; Torgny Näsholm; Kerstin Huss-Danell

2008-01-01

110

What Amino Acid Properties Affect Protein Evolution?  

Microsoft Academic Search

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

Xuhua Xia; Wen-Hsiung Li

1998-01-01

111

Substrate specificity of the amino acid transporter PAT1.  

PubMed

The proton coupled amino acid transporter PAT1 expressed in intestine, brain, and other organs accepts L- and D-proline, glycine, and L-alanine but also pharmaceutically active amino acid derivatives such as 3-amino-1-propanesulfonic acid, L-azetidine-2-carboxylic acid, and cis-4-hydroxy-D-proline as substrates. We systematically analyzed the structural requirements for PAT1 substrates by testing 87 amino acids, proline homologs, indoles, and derivatives. Affinity data and effects on membrane potential were determined using Caco-2 cells. For aliphatic amino acids, a blocked carboxyl group, the distance between amino and carboxyl group, and the position of the hydroxyl group are affinity limiting factors. Methylation of the amino group enhances substrate affinity. Hetero atoms in the proline template are well tolerated. Aromatic alpha-amino acids display low affinity. PAT1 interacts strongly with heterocyclic aromatic acids containing an indole scaffold. The structural requirements of PAT1 substrates elucidated in this study will be useful for the development of prodrugs. PMID:16699824

Metzner, L; Neubert, K; Brandsch, M

2006-05-15

112

Amino acid composition of some Mexican foods.  

PubMed

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

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

2005-06-01

113

Adsorption of amino acids on hydrophilic surfaces  

NASA Astrophysics Data System (ADS)

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

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

2008-06-01

114

Amino Acid Catabolism and Malic Enzyme in Differentiating Dictyostelium discoideum  

PubMed Central

Amino acids produced from protein degradation are the major energy source for differentiation and aging in Dictyostelium discoideum. Considering the reactions involved in the conversion of amino acids from an average protein into tricarboxylic acid cycle intermediates, a route from a cycle intermediate (probably malate) to acetyl coenzyme A is required for the complete utilization of amino acids. Citrate was isolated from cells pulse-labeled with 14C-labeled amino acids and was cleaved with citrate lyase. When cells were pulse-labeled with [U-14C]-glutamate the specific radioactivity of the acetate and oxaloacetate portions of citrate were consistent with the conclusion that one-third of the carbon flowing through the tricarboxylic acid cycle is removed for the synthesis of acetyl coenzyme A. The data were also consistent with the patterns of carbon flux required to maintain steady-state levels of cycle intermediates in cells catabolizing amino acids. It is suggested that the malic enzyme (EC 1.1.1.40) catalyzes the synthesis of acetyl coenzyme A from malate and is responsible for the observed citrate labeling pattern. In cell extracts the activity of this enzyme increased markedly with the onset of differentiation. The properties of partially purified (40-fold) malic enzyme isolated at culmination indicated that the enzyme was allosteric and was positively affected by aspartate and glutamate. Thus, amino acid production from protein degradation would stimulate a reaction essential for the efficient utilization of these amino acids for energy.

Kelleher, Joanne K.; Kelly, Patrick J.; Wright, Barbara E.

1979-01-01

115

Three adjacent serines in the extracellular domains of the CaR are required for L-amino acid-mediated potentiation of receptor function.  

PubMed

The extracellular calcium (Ca(2+)(o))-sensing receptor (CaR) is a key player in Ca(2+)(o) homeostasis. The activity of CaR can be potentiated by various l-amino acids. In this study, we examined whether conserved amino acid residues involved in the binding of glutamate to metabotropic glutamate receptors (mGluRs) also participate in the potentiation of the activity of CaR by l-phenylalanine. Ser-170 corresponding to Thr-188 in rat mGluR1a appears to be important for the modulating actions of phenylalanine. In the presence of phenylalanine, a mutant CaR with a single mutation S170A showed no significant decrease in its EC(50) for stimulation by Ca(2+)(o) and a modest increase in its maximal activity. In addition, mutating Ser-169 and Ser-171 together with Ser-170 yielded a more complete block of the phenylalanine modulation than did the single mutation. The presence of the triple mutation, S169A/S170A/S171A, also eliminated phenylalanine potentiation of the activities of heterodimeric receptors in which one of the monomeric receptors had intact triple serines (A877Stop). The putative amino acid binding site of the CaR is probably close to or structurally dependent on the Ca(2+)(o) binding sites of the receptor, because mutant CaRs with mutations in the putative amino acid binding site exhibited severely reduced responses to Ca(2+)(o). PMID:12095982

Zhang, Zaixiang; Qiu, Weiying; Quinn, Stephen J; Conigrave, Arthur D; Brown, Edward M; Bai, Mei

2002-07-02

116

Transport of Amino Acids to the Maize Root 1  

PubMed Central

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

Oaks, Ann

1966-01-01

117

Amino Acid Uptake in Arbuscular Mycorrhizal Plants  

PubMed Central

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

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

2012-01-01

118

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

Microsoft Academic Search

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

JAN VEL; ROMAN KUBEC; KAREL CEJPEK

2006-01-01

119

C acid decarboxylases required for C photosynthesis are active in the mid-vein of the C species Arabidopsis thaliana, and are important in sugar and amino acid metabolism.  

PubMed

Cells associated with veins of petioles of C(3) tobacco possess high activities of the decarboxylase enzymes required in C(4) photosynthesis. It is not clear whether this is the case in other C(3) species, nor whether these enzymes provide precursors for specific biosynthetic pathways. Here, we investigate the activity of C(4) acid decarboxylases in the mid-vein of Arabidopsis, identify regulatory regions sufficient for this activity, and determine the impact of removing individual isoforms of each protein on mid-vein metabolite profiles. This showed that radiolabelled malate and bicarbonate fed to the xylem stream were incorporated into soluble and insoluble material in the mid-vein of Arabidopsis leaves. Compared with the leaf lamina, mid-veins possessed high activities of NADP-dependent malic enzyme (NADP-ME), NAD-dependent malic enzyme (NAD-ME) and phosphoenolpyruvate carboxykinase (PEPCK). Transcripts derived from both NAD-ME, one PCK and two of the four NADP-ME genes were detectable in these veinal cells. The promoters of each decarboxylase gene were sufficient for expression in mid-veins. Analysis of insertional mutants revealed that cytosolic NADP-ME2 is responsible for 80% of NADP-ME activity in mid-veins. Removing individual decarboxylases affected the abundance of amino acids derived from pyruvate and phosphoenolpyruvate. Reducing cytosolic NADP-ME activity preferentially affected the sugar content, whereas abolishing NAD-ME affected both the amino acid and the glucosamine content of mid-veins. PMID:19807880

Brown, Naomi J; Palmer, Ben G; Stanley, Susan; Hajaji, Hana; Janacek, Sophie H; Astley, Holly M; Parsley, Kate; Kajala, Kaisa; Quick, W Paul; Trenkamp, Sandra; Fernie, Alisdair R; Maurino, Veronica G; Hibberd, Julian M

2009-10-06

120

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

Microsoft Academic Search

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

Rui Alves; Michael A. Savageau

2005-01-01

121

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

Microsoft Academic Search

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

E. R. Stadtman; R. L. Levine

2003-01-01

122

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

123

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

PubMed Central

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

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

2008-01-01

124

GCN2 protein kinase is required to activate amino acid deprivation responses in mice treated with the anti-cancer agent L-asparaginase.  

PubMed

Asparaginase depletes circulating asparagine and glutamine, activating amino acid deprivation responses (AADR) such as phosphorylation of eukaryotic initiation factor 2 (p-eIF2) leading to increased mRNA levels of asparagine synthetase and CCAAT/enhancer-binding protein beta homologous protein (CHOP) and decreased mammalian target of rapamycin complex 1 (mTORC1) signaling. The objectives of this study were to assess the role of the eIF2 kinases and protein kinase R-like endoplasmic reticulum resident kinase (PERK) in controlling AADR to asparaginase and to compare the effects of asparaginase on mTORC1 to that of rapamycin. In experiment 1, asparaginase increased hepatic p-eIF2 in wild-type mice and mice with a liver-specific PERK deletion but not in GCN2 null mice nor in GCN2-PERK double null livers. In experiment 2, wild-type and GCN2 null mice were treated with asparaginase (3 IU per g of body weight), rapamycin (2 mg per kg of body weight), or both. In wild-type mice, asparaginase but not rapamycin increased p-eIF2, p-ERK1/2, p-Akt, and mRNA levels of asparagine synthetase and CHOP in liver. Asparaginase and rapamycin each inhibited mTORC1 signaling in liver and pancreas but maximally together. In GCN2 null livers, all responses to asparaginase were precluded except CHOP mRNA expression, which remained partially elevated. Interestingly, rapamycin blocked CHOP induction by asparaginase in both wild-type and GCN2 null livers. These results indicate that GCN2 is required for activation of AADR to asparaginase in liver. Rapamycin modifies the hepatic AADR to asparaginase by preventing CHOP induction while maximizing inhibition of mTORC1. PMID:19783659

Bunpo, Piyawan; Dudley, Allison; Cundiff, Judy K; Cavener, Douglas R; Wek, Ronald C; Anthony, Tracy G

2009-09-25

125

GCN2 Protein Kinase Is Required to Activate Amino Acid Deprivation Responses in Mice Treated with the Anti-cancer Agent l-Asparaginase*  

PubMed Central

Asparaginase depletes circulating asparagine and glutamine, activating amino acid deprivation responses (AADR) such as phosphorylation of eukaryotic initiation factor 2 (p-eIF2) leading to increased mRNA levels of asparagine synthetase and CCAAT/enhancer-binding protein ? homologous protein (CHOP) and decreased mammalian target of rapamycin complex 1 (mTORC1) signaling. The objectives of this study were to assess the role of the eIF2 kinases and protein kinase R-like endoplasmic reticulum resident kinase (PERK) in controlling AADR to asparaginase and to compare the effects of asparaginase on mTORC1 to that of rapamycin. In experiment 1, asparaginase increased hepatic p-eIF2 in wild-type mice and mice with a liver-specific PERK deletion but not in GCN2 null mice nor in GCN2-PERK double null livers. In experiment 2, wild-type and GCN2 null mice were treated with asparaginase (3 IU per g of body weight), rapamycin (2 mg per kg of body weight), or both. In wild-type mice, asparaginase but not rapamycin increased p-eIF2, p-ERK1/2, p-Akt, and mRNA levels of asparagine synthetase and CHOP in liver. Asparaginase and rapamycin each inhibited mTORC1 signaling in liver and pancreas but maximally together. In GCN2 null livers, all responses to asparaginase were precluded except CHOP mRNA expression, which remained partially elevated. Interestingly, rapamycin blocked CHOP induction by asparaginase in both wild-type and GCN2 null livers. These results indicate that GCN2 is required for activation of AADR to asparaginase in liver. Rapamycin modifies the hepatic AADR to asparaginase by preventing CHOP induction while maximizing inhibition of mTORC1.

Bunpo, Piyawan; Dudley, Allison; Cundiff, Judy K.; Cavener, Douglas R.; Wek, Ronald C.; Anthony, Tracy G.

2009-01-01

126

A New Naturally Occurring AminoAcid  

Microsoft Academic Search

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

Elizabeth Work

1950-01-01

127

Plasma amino acids in anorexia nervosa  

Microsoft Academic Search

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

D Moyano; MA Vilaseca; R Artuch; N Lambruschini

1998-01-01

128

Intramolecular arylation of amino acid enolates.  

PubMed

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

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

2013-09-26

129

Reexamination of Amino Acids in Lunar Soil.  

National Technical Information Service (NTIS)

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

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

1993-01-01

130

Urinary amino acid analysis: a comparison of iTRAQ-LC-MS/MS, GC-MS, and amino acid analyzer.  

PubMed

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

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

2009-05-15

131

Amino acid signatures in carbonaceous meteorites  

NASA Astrophysics Data System (ADS)

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

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

2002-02-01

132

Amino Acids in the Martian Meteorite Nakhla  

NASA Astrophysics Data System (ADS)

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

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

1999-08-01

133

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

134

Amino Acid Concentrations in Rumen Fluid  

PubMed Central

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

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

1967-01-01

135

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

PubMed Central

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

Ito, Len; Shiraki, Kentaro; Yamaguchi, Hiroshi

2010-01-01

136

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

Microsoft Academic Search

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

R. Caputo; L. Longobardo

2007-01-01

137

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

138

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

139

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

140

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

141

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

PubMed Central

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

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

2003-01-01

142

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

PubMed Central

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

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

2011-01-01

143

THE IMMUNOGENICITY OF DINITROPHENYL AMINO ACIDS  

PubMed Central

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

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

1969-01-01

144

Essential amino acids are primarily responsible for the amino acid stimulation of muscle protein anabolism in healthy elderly adults  

PubMed Central

Background Nutritional supplementation may be used to treat muscle loss with aging (sarcopenia). However, if physical activity does not increase, the elderly tend to compensate for the increased energy delivered by the supplements with reduced food intake, which results in a calorie substitution rather than supplementation. Thus, an effective supplement should stimulate muscle anabolism more efficiently than food or common protein supplements. We have shown that balanced amino acids stimulate muscle protein anabolism in the elderly, but it is unknown whether all amino acids are necessary to achieve this effect. Objective We assessed whether nonessential amino acids are required in a nutritional supplement to stimulate muscle protein anabolism in the elderly. Design We compared the response of muscle protein metabolism to either 18 g essential amino acids (EAA group: n = 6, age 69 ± 2 y; x? ± SD) or 40 g balanced amino acids (18 g essential amino acids + 22 g nonessential amino acids, BAA group; n = 8, age 71 ± 2 y) given orally in small boluses every 10 min for 3 h to healthy elderly volunteers. Muscle protein metabolism was measured in the basal state and during amino acid administration via l-[ring-2H5]phenylalanine infusion, femoral arterial and venous catheterization, and muscle biopsies. Results Phenylalanine net balance (in nmol · min?1 · 100 mL leg volume?1) increased from the basal state (P < 0.01), with no differences between groups (BAA: from ?16 ± 5 to 16 ± 4; EAA: from ?18 ± 5 to 14 ± 13) because of an increase (P < 0.01) in muscle protein synthesis and no change in breakdown. Conclusion Essential amino acids are primarily responsible for the amino acid–induced stimulation of muscle protein anabolism in the elderly.

Volpi, Elena; Kobayashi, Hisamine; Sheffield-Moore, Melinda; Mittendorfer, Bettina; Wolfe, Robert R

2011-01-01

145

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

PubMed Central

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

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

2012-01-01

146

Mutational analysis of the L1 neuronal cell adhesion molecule identifies membrane-proximal amino acids of the cytoplasmic domain that are required for cytoskeletal anchorage.  

PubMed

The preferential localization of the L1 cell adhesion molecule in the axons and growth cones of differentiating neurons suggests the existence of a mechanism for targeting or anchoring the molecule to these locations. We have used B28 glioma cells, which have an extremely flattened morphology, as a model system to study the organization of L1 on the cell structure. Transfection of L1 cDNA into B28 cells results in expression of the L1 protein in organized linear cell surface arrays which are codistributed with cytoskeletal stress fibers, but not with microtubles or intermediate filaments. Transfection studies with L1 deletion mutants identify the juxtamembrane segment of the cytoplasmic domain as the critical entity for arrangement of L1 into ordered cell surface arrays. The seventh cytoplasmic amino acid of L1, lysine 1150, and to a lesser extent the fourth cytoplasmic amino acid, lysine 1147, appear to be critical residues for maintaining normal L1 anchorage and distribution. PMID:9245498

Dahlin-Huppe, K; Berglund, E O; Ranscht, B; Stallcup, W B

1997-01-01

147

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

148

Chromatography of Rare Basic Amino Acids.  

National Technical Information Service (NTIS)

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

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

1973-01-01

149

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

PubMed Central

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

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

2008-01-01

150

Molecular Biology: Proteins, Polypeptides, Amino Acids.  

National Technical Information Service (NTIS)

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

1982-01-01

151

How to build optically active ? -amino acids  

Microsoft Academic Search

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

M. Calmes; J. Daunis

1999-01-01

152

Allylic halogenation of unsaturated amino acids.  

PubMed

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

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

2003-07-21

153

Advanced biosensors for amino acid detection  

NASA Astrophysics Data System (ADS)

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

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

1989-10-01

154

Molecular Biology: Proteins, Polypeptides, Amino Acids.  

National Technical Information Service (NTIS)

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

1984-01-01

155

Amino Acids Mediate Postprandial Jejunal Proabsorption  

Microsoft Academic Search

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

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

1995-01-01

156

Adsorption of amino acids on hydrophilic surfaces  

Microsoft Academic Search

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

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

2008-01-01

157

Amino acid selective labeling and unlabeling for protein resonance assignments.  

PubMed

Structural characterization of proteins by NMR spectroscopy begins with the process of sequence specific resonance assignments in which the (1)H, (13)C and (15)N chemical shifts of all backbone and side-chain nuclei in the polypeptide are assigned. This process requires different isotope labeled forms of the protein together with specific experiments for establishing the sequential connectivity between the neighboring amino acid residues. In the case of spectral overlap, it is useful to identify spin systems corresponding to the different amino acid types selectively. With isotope labeling this can be achieved in two ways: (i) amino acid selective labeling or (ii) amino acid selective 'unlabeling'. This chapter describes both these methods with more emphasis on selective unlabeling describing the various practical aspects. The recent developments involving combinatorial selective labeling and unlabeling are also discussed. PMID:23076581

Jaipuria, Garima; Krishnarjuna, B; Mondal, Somnath; Dubey, Abhinav; Atreya, Hanudatta S

2012-01-01

158

Evaluation of amino acids as turfgrass nematicides.  

PubMed

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

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

2010-12-01

159

Amino Acid Patterns around Disulfide Bonds  

PubMed Central

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

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

2010-01-01

160

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

Code of Federal Regulations, 2010 CFR

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

2009-07-01

161

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

162

Amino acid scoring patterns for protein quality assessment.  

PubMed

The 1985 FAO/WHO/UNU protein report defined reference amino acid patterns for infants based on breast milk and for preschool children, schoolchildren and adults from age specific estimates of dietary indispensible amino acid requirements divided by the safe protein requirement for each age group. This report argued that the protein quality of a diet should be estimated from its digestibility adjusted by its amino acid score calculated from its limiting amino acid in comparison with the reference amino acid pattern. Subsequently a joint FAO/WHO expert consultation on protein quality evaluation (1991) endorsed this protein digestibility-corrected score approach. However it rejected the adult scoring pattern identified in the 1985 report arguing that the amino acid values for this pattern were too low. As an interim measure it suggested that the scoring pattern for preschool children should be used for all age groups apart from infants. The recent WHO/FAO/UNU (2007) report endorsed the 1985 report in recommending the amino acid content of breast milk as the best estimate of infant amino acid requirements. However it was only able to identify reliable requirement values for adults and adopted a factorial approach to derivation of age-related scoring patterns. This utilized the adult pattern for maintenance, and the pattern of human tissue protein for growth. Thus scoring patterns were derived for children aged 0·5, 1-2, 3-10, 11-14, 15-18 years and for adults. The total dietary amino acid requirements calculated for these age groups were divided by the mean protein requirement to give the scoring pattern which should be used to adjust digestible intakes to identify the available protein in specific diets. However because the adult values were determined in subjects at protein intakes much higher than the mean minimum protein requirement, i.e. at 1 g/kg/d rather than 0·66 g/kg/d, the pattern is likely to include higher values than the minimum requirement and should therefore be referenced against the safe allowance. PMID:23107544

Millward, D Joe

2012-08-01

163

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

Microsoft Academic Search

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

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

1993-01-01

164

A Net Carbohydrate and Protein System for Evaluating Cattle Diets: IV. Predicting Amino Acid Adequacy  

Microsoft Academic Search

The Cornell Net Carbohydrate and Protein System was modified to include an amino acid submodel for predicting the adequacy of absorbed essential amino acids in cattle diets. Equations for predicting the supply of and requirements for ab- sorbed essential amino acids are described and presented. The model was evaluated for its ability to predict observed duodenal flows of nitrogen, nonam-

J. D. O'Connorl; C. J. Sniffen; D. G. Fox; W. Chalupa

165

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

166

A putative amino acid transporter of the SLC6 family is up-regulated by lithium and is required for resistance to lithium toxicity in Drosophila  

PubMed Central

Lithium is an efficacious drug for the treatment of mood disorders, and its application is also considered a potential therapy for brain damage. However, the mechanisms underlying lithium’s therapeutic action and toxic effects in the nervous system remain largely elusive. Here we report on the use of a versatile genetic model, the fruit fly Drosophila melanogaster, to discover novel molecular components involved in the lithium-responsive neurobiological process. We previously identified CG15088, which encodes a putative nutrient amino acid transporter of the solute carrier 6 (SLC6) family, as one of the genes most significantly up-regulated in response to lithium treatment. This gene was the only SLC6 gene induced by lithium, and was thus designated as Lithium-inducible SLC6 transporter or List. Either RNAi-mediated knockdown or complete deletion of List resulted in a remarkable increase in the susceptibility of adult flies to lithium’s toxic effects, whereas transgenic expression of wild-type List significantly suppressed the lithium hypersensitive phenotype of List-deficient flies. Other ions such as sodium, potassium and chloride did not induce List up-regulation, nor did they affect the viability of flies with suppressed List expression. These results indicate that lithium’s biochemical or physical properties, rather than general osmotic responses, are responsible for the lithium-induced up-regulation of List, as well as for the lithium-susceptible phenotype observed in List knockdown flies. Interestingly, flies became significantly more susceptible to lithium toxicity when List RNAi was specifically expressed in glia than when it was expressed in neurons or muscles, which is consistent with potential glial expression of List. These results show that the List transporter confers resistance to lithium toxicity, possibly as a consequence of its amino acid transporter activity in CNS glia. Our results have provided a new avenue of investigation toward a better understanding of the molecular and cellular mechanisms that underlie lithium-responsive neurobiological process.

Kasuya, Junko; Kaas, Garrett A.; Kitamoto, Toshihiro

2009-01-01

167

Identification of amino acids in the transmembrane and juxtamembrane domains of the platelet-derived growth factor receptor required for productive interaction with the bovine papillomavirus E5 protein.  

PubMed Central

The bovine papillomavirus E5 protein forms a stable complex with the cellular platelet-derived growth factor (PDGF) beta receptor, resulting in receptor activation and cell transformation. Amino acids in both the putative transmembrane domain and extracytoplasmic carboxyl-terminal domain of the E5 protein appear important for PDGF receptor binding and activation. Previous analysis indicated that the transmembrane domain of the receptor was also required for complex formation and receptor activation. Here we analyzed receptor chimeras and point mutants to identify specific amino acids in the PDGF beta receptor required for productive interaction with the E5 protein. These receptor mutants were analyzed in murine Ba/F3 cells, which do not express endogenous receptor. Our results confirmed the importance of the transmembrane domain of the receptor for complex formation, receptor tyrosine phosphorylation, and mitogenic signaling in response to the E5 protein and established that the threonine residue in this domain is required for these activities. In addition, a positive charge in the extracellular juxtamembrane domain of the receptor was required for E5 interaction and signaling, whereas replacement of the wild-type lysine with either a neutral or acidic amino acid inhibited E5-induced receptor activation and transformation. All of the receptor mutants defective for activation by the E5 protein responded to acute treatment with PDGF and to stable expression of v-Sis, a form of PDGF. The required juxtamembrane lysine and transmembrane threonine are predicted to align precisely on the same face of an alpha helix packed in a left-handed coiled-coil geometry. These results establish that the E5 protein and v-Sis recognize distinct binding sites on the PDGF beta receptor and further clarify the nature of the interaction between the viral transforming protein and its cellular target.

Petti, L M; Reddy, V; Smith, S O; DiMaio, D

1997-01-01

168

Aromatic amino acid transport in Yersinia pestis.  

PubMed Central

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

Smith, P B; Montie, T C

1975-01-01

169

Amino acid survival in large cometary impacts  

NASA Astrophysics Data System (ADS)

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

Pierazzo, E.; Chyba, C. F.

1999-11-01

170

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

PubMed

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

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

1990-04-01

171

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

172

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

Microsoft Academic Search

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

A. C. Chakrabarti

1994-01-01

173

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

Microsoft Academic Search

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

Christian Fleck; J. Pertsch

1998-01-01

174

Evolutionary changes reflected by the cellular amino acid composition  

Microsoft Academic Search

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

K. Sorimachi

1999-01-01

175

The amino acid composition of mammalian and bacterial cells  

Microsoft Academic Search

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

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

1997-01-01

176

Amino Acid Profiles of Bivalve Mollusks from Beibu Gulf, China  

Microsoft Academic Search

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

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

2012-01-01

177

Amino Acid Profiles of Bivalve Mollusks from Beibu Gulf, China  

Microsoft Academic Search

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

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

2011-01-01

178

Killing of intraerythrocytic Plasmodium falciparum by lysosomotropic amino acid esters  

Microsoft Academic Search

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

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

2003-01-01

179

AAindex: amino acid index database, progress report 2008  

Microsoft Academic Search

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

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

2008-01-01

180

Renal Transport of Endogenous Amino Acids  

Microsoft Academic Search

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

Ch. Fleck

1992-01-01

181

Early parenteral feeding of amino acids.  

PubMed Central

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

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

1989-01-01

182

Combinatorial codon-based amino acid substitutions  

PubMed Central

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

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

2004-01-01

183

Inhibited muscle amino acid uptake in sepsis.  

PubMed Central

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

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

1986-01-01

184

The Genetics of Heteromeric Amino Acid Transporters  

NSDL National Science Digital Library

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

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

2005-04-01

185

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

Microsoft Academic Search

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

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

1988-01-01

186

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

187

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

PubMed Central

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

Yamaguchi, Shigenori; Komeda, Hidenobu; Asano, Yasuhisa

2007-01-01

188

Non-natural amino acids for tumor imaging using positron emission tomography and single photon emission computed tomography  

Microsoft Academic Search

Amino acids are required nutrients for proliferating tumor cells, and amino acid transport is upregulated in many tumor types.\\u000a Studies of radiolabeled amino acids in animals and humans demonstrate that amino acid based tracers have advantageous characteristics\\u000a relative to 2-[18F]fluoro-2-deoxyglucose in certain tumors, particularly brain gliomas. Non-natural amino acids for tumor imaging generally\\u000a have greater metabolic stability and can be

Jonathan McConathy; Mark M. Goodman

2008-01-01

189

Duplication-induced mutation of a new Neurospora gene required for acetate utilization: properties of the mutant and predicted amino acid sequence of the protein product.  

PubMed Central

A cloned Neurospora crassa genomic sequence, selected as preferentially transcribed when acetate was the sole carbon source, was introduced in extra copies at ectopic loci by transformation. Sexual crossing of transformants yielded acetate nonutilizing mutants with methylation and restriction site changes within both the ectopic DNA and the normally located gene. Such changes are typical of the duplication-induced premeiotic disruption (the RIP effect) first described by Selker et al. (E. U. Selker, E. B. Cambareri, B. C. Jensen, and K. R. Haack, Cell 51:741-752, 1987). The mutants had the unusual phenotype of growth on ethanol but not on acetate as the carbon source. In a cross to the wild type of a mutant strain in which the original ectopic gene sequence had been removed by segregation, the acetate nonutilizing phenotype invariably segregated together with a RIP-induced EcoRI site at the normal locus. This mutant was transformed to the ability to use acetate by the cloned sequence. The locus of the mutation, designated acu-8, was mapped between trp-3 and un-15 on linkage group 2. The transcribed portion of the clone, identified by probing with cDNA, was sequenced, and a putative 525-codon open reading frame with two introns was identified. The codon usage was found to be strongly biased in a way typical of most Neurospora genes sequenced so far. The predicted amino acid sequence shows no significant resemblance to anything previously recorded. These results provide a first example of the use of the RIP effect to obtain a mutant phenotype for a gene previously known only as a transcribed wild-type DNA sequence. Images

Marathe, S; Connerton, I F; Fincham, J R

1990-01-01

190

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

PubMed

ERH is a small, highly evolutionarily conserved nuclear protein of unknown function. Its three-dimensional structure is absolutely unique and it can form a homodimer through a ? sheet surface. ERH has been shown to interact, among others, with PDIP46/SKAR and Ciz1. When coexpressed with the latter protein, ERH accumulates in replication foci in the nucleus of HeLa cells. Here, we report that when ERH is coexpressed with PDIP46/SKAR in HeLa cells, it is recruited to nuclear speckles, and identify amino acid residues critical for targeting ERH to both these subnuclear structures. ERH H3A Q9A shows a diminished recruitment to nuclear speckles but it is recruited to replication foci. ERH E37A T51A is very poorly recruited to replication foci while still accumulating in nuclear speckles. Consequently, ERH H3A Q9A E37A T51A is recruited neither to nuclear speckles nor to replication foci. The lack of interactions of these three ERH forms with PDIP46/SKAR and/or Ciz1 was further confirmed in vitro by GST pull-down assay. The residues whose substitutions interfere with the accumulation in nuclear speckles are situated on the ? sheet surface of ERH, indicating that only the monomer of ERH can interact with PDIP46/SKAR. Substitutions affecting the recruitment to replication foci map to the other side of ERH, near a long loop between the ?1 and ?2 helices, thus both the monomer and the dimer of ERH could interact with Ciz1. The construction of the ERH mutants not recruited to nuclear speckles or replication foci will facilitate further studies on ERH actions in these subnuclear structures. PMID:24015320

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

2013-08-28

191

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

192

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

SciTech Connect

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

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

1987-11-01

193

Amino acids attached to transfer ribonucleic acid in vivo.  

PubMed Central

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

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

1975-01-01

194

Amino Acid Sequence of Human Cholinesterase.  

National Technical Information Service (NTIS)

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

O. Lockridge

1985-01-01

195

The Exchangeability of Amino Acids in Proteins  

PubMed Central

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

Yampolsky, Lev Y.; Stoltzfus, Arlin

2005-01-01

196

Dietary Supplements and Sports Performance: Amino Acids  

Microsoft Academic Search

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

Melvin Williams

2005-01-01

197

Amino acid modifications on tRNA  

PubMed Central

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

Yuan, Jing; Sheppard, Kelly; Soll, Dieter

2008-01-01

198

Optimization of short amino acid sequences classifier  

NASA Astrophysics Data System (ADS)

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

Barcz, Aleksy; Szyma?ski, Zbigniew

2012-05-01

199

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

200

Protein tolerance to random amino acid change  

Microsoft Academic Search

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

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

2004-01-01

201

Dietary Supplements and Sports Performance: Amino Acids  

PubMed Central

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

Williams, Melvin

2005-01-01

202

Amino acid fermentation by Bacteroides melaninogenicus  

Microsoft Academic Search

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

Ann Wahren; R. J. Gibbons

1970-01-01

203

Muscle amino acid pattern in obese rats  

Microsoft Academic Search

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

MC Herrero; X Remesar; C Bladé; LI Arola

1997-01-01

204

Amino Acid Metabolism of Pea Leaves  

PubMed Central

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

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

1977-01-01

205

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.

2010-01-01

206

Molecular Evolution of Plant AAP and LHT Amino Acid Transporters  

PubMed Central

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

Tegeder, Mechthild; Ward, John M.

2012-01-01

207

Quantitation of fourteen urinary alpha-amino acids using isobutane gas chromatography chemical ionization mass spectrometry with 13C amino acids as internal standards.  

PubMed

Isobutane chemical ionization gas chromatography mass spectometry of the N-trifluoroacetyl-carboxy-n-butyl ester derivatives of amino acids, using a commercial per-13C-amino acid mixture as internal standards, provided a sensitive and specific method for quantitative analysis of fourteen urinary alpha-amino acids. A computer controlled quadrupole mass spectrometer was used in a selected ion monitoring mode to record the ion current due to the protonated molecular ions of each alpha-amino acid/13C analogue pair. BASIC programmes located peak maxima, and using previously established standard curves, calculated the amino acid content on the bases of both peak height and peak area ratios. Duplicate amino acid analyses are possible on 5 microliter of urine. Instrumental analysis required 25 minutes, automated data processing 10 minutes, and sample preparation 2 hours. Detection limits approached 1 ng with a typical mean standard deviation of 2% for the instrumental analysis. PMID:6452181

Finlayson, P J; Christopher, R K; Duffield, A M

1980-10-01

208

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

209

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

Microsoft Academic Search

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

A. M. Rojas; R. Devés

1999-01-01

210

Amino acid utilization by LM strain mouse cells in a chemically defined medium  

Microsoft Academic Search

Summary  The amino acid requirements of strain L-M mouse cells grown in a chemically defined medium (2×Eagle) containing only the 13\\u000a essential amino acids (EAA) were investigated. Medium and acid hydrolysate samples were analyzed for amino acid content by\\u000a the method of ion exchange chromatography. The extent of utilization of the EAA differed;e.g. after 120 hr of cell growth without medium

Gary D. Stoner; Donald J. Merchant

1972-01-01

211

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

2012-09-18

212

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

Microsoft Academic Search

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

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

2008-01-01

213

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

Microsoft Academic Search

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

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

2011-01-01

214

Amino acid distribution of cereals in commerical mill products  

Microsoft Academic Search

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

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

1981-01-01

215

Reversed Phase Thin Layer Chromatography of Amino Acids  

Microsoft Academic Search

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

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

1984-01-01

216

Branched-Chain Amino Acid Metabolism in Arabidopsis thaliana  

PubMed Central

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

Binder, Stefan

2010-01-01

217

AMINO ACID CROSS RESISTANCE IN AGROBACTERIUM TUMEFACIENS  

PubMed Central

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

Beardsley, Robert E.

1962-01-01

218

Creatinine Inhibits D-Amino Acid Oxidase  

Microsoft Academic Search

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

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

2002-01-01

219

Amino acid imbalance and incomplete viral replication  

Microsoft Academic Search

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

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

1964-01-01

220

Secondary Transport of Amino Acids in Prokaryotes  

Microsoft Academic Search

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

H. Jung; T. Pirch; D. Hilger

2006-01-01

221

Amino acids: metabolism, functions, and nutrition  

Microsoft Academic Search

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

Guoyao Wu

2009-01-01

222

Alimentary proteins, amino acids and cholesterolemia  

Microsoft Academic Search

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

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

2010-01-01

223

Amino Acid Composition of Crystalline Botulinum Toxin, Type A.  

National Technical Information Service (NTIS)

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

D. Stefanye

1965-01-01

224

A Search for Extraterrestrial Amino Acids in Carbonaceous Antarctic Micrometeorites  

NASA Astrophysics Data System (ADS)

Antarctic micrometeorites (AMMs) in the 100-400 ?m 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 ?-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 (~280 ppm), and the AIB/isovaline ratio (>=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, Karen L. F.; Engrand, Cécile; Glavin, Daniel P.; Bada, Jeffrey L.; Maurette, Michel

1998-10-01

225

Alimentary proteins, amino acids and cholesterolemia.  

PubMed

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

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

2009-01-30

226

Nutritional and medicinal aspects of d -amino acids  

Microsoft Academic Search

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

Mendel FriedmanCarol; Carol E. Levin

227

Investigation of amine amino acid salts for carbon dioxide absorption  

Microsoft Academic Search

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

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

2010-01-01

228

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

Microsoft Academic Search

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

Sang Hyun Park; Seung Hwan Lee; Sang Yup Lee

2001-01-01

229

A partial amino acid sequence for sheep haemoglobin A  

PubMed Central

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

Beale, D.

1967-01-01

230

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

Microsoft Academic Search

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

Philip NEWSHOLME; Lorraine BRENNAN; Blanca RUBI; Pierre MAECHLER

2005-01-01

231

Genetic Engineering of Amino Acid Metabolism in Plants  

Microsoft Academic Search

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

Shmuel Galili; Rachel Amir; Gad Galili

2008-01-01

232

Soil amino acid composition across a boreal forest successional sequence  

Microsoft Academic Search

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

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

2009-01-01

233

Amino acid biogeo- and stereochemistry in coastal Chilean sediments  

Microsoft Academic Search

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

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

2006-01-01

234

Amino Acid Pair Interchanges at Spatially Conserved Locations  

Microsoft Academic Search

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

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

1996-01-01

235

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

Microsoft Academic Search

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

Mamoru Wakayama; Kazuaki Yoshimune; Yoshihiko Hirose; Mitsuaki Moriguchi

2003-01-01

236

Developmental Regulation of Amino Acid Transport in Neurospora crassa  

PubMed Central

Conidia of Neurospora crassa exhibit an ability to transport various amino acids against a concentration gradient. The conidial transport system has previously been characterized in terms of kinetics, competitions, and genetic control. This study describes the development of a new and highly active transport capability which is elaborated during the early stages of development but prior to evident germination. It has been named “postconidial” transport activity and represents as much as 20-fold greater initial rates as compared to those observed with conidia. Development of the postconidial transport activity requires protein synthesis and can be partially repressed when the substrate amino acid is present during the developmental preincubation period. A mutant has been utilized which exhibits normal conidial but fails to develop normal postconidial transport activity for any amino acid examined. Although temperature optimum and pH dependence are similar in conidial and postconidial systems, there is evidence that the new activity is not a simple amplification of an existing capability. This is reflected as a change in competition patterns between particular amino acids as development proceeds.

Tisdale, J. H.; DeBusk, A. Gib

1970-01-01

237

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

PubMed

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

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

2013-09-25

238

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

Microsoft Academic Search

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

HIROSHI ITOH

2010-01-01

239

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

Microsoft Academic Search

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

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

240

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

Microsoft Academic Search

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

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

1999-01-01

241

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

PubMed Central

Urinary amino acid analysis is typically done by cation-exchange chromatography followed by post-column derivatization with ninhydrin and UV detection. This method lacks throughput and specificity. Two recently introduced stable isotope ratio mass spectrometric methods promise to overcome those shortcomings. Using two blinded sets of urine replicates and a certified amino acid standard, we compared the precision and accuracy of gas chromatography/mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) of propyl chloroformate and iTRAQ® derivatized amino acids, respectively, to conventional amino acid analysis. The GC-MS method builds on the direct derivatization of amino acids in diluted urine with propyl chloroformate, GC separation and mass spectrometric quantification of derivatives using stable isotope labeled standards. The LC-MS/MS method requires prior urinary protein precipitation followed by labeling of urinary and standard amino acids with iTRAQ® tags containing different cleavable reporter ions distinguishable by MS/MS fragmentation. Means and standard deviations of percent technical error (%TE) computed for 20 amino acids determined by amino acid analyzer, GC-MS, and iTRAQ®-LC-MS/MS analyses of 33 duplicate and triplicate urine specimens were 7.27±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.

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

2009-01-01

242

“Facilitated” Amino Acid Transport Is Upregulated in Brain Tumors  

Microsoft Academic Search

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

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

1998-01-01

243

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

244

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

245

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

PubMed Central

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

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

2008-01-01

246

How much protein do parenteral amino acid mixtures provide?  

PubMed

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

Hoffer, L John

2011-10-19

247

Organic geochemistry of amino acids: Precambrian to recent  

SciTech Connect

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

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

1985-01-01

248

Protein tolerance to random amino acid change  

PubMed Central

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

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

2004-01-01

249

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

Microsoft Academic Search

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

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

2008-01-01

250

Papaya proteinase IV amino acid sequence.  

PubMed

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

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

1989-11-20

251

Amino Acid Formation on Saturn's Inner Satellites  

NASA Astrophysics Data System (ADS)

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

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

2002-09-01

252

Extraterrestrial amino acids in the Almahata Sitta meteorite  

NASA Astrophysics Data System (ADS)

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

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

2010-10-01

253

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

254

Amino acid analysis for meat protein evaluation.  

PubMed

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

Ashworth, R B

255

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

NASA Astrophysics Data System (ADS)

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

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

256

Salts of amino acids with hexafluorosilicate anion  

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

257

Amino Acid Substitutions at Ambler Position Gly238 in the SHV-1  Lactamase: Exploring Sequence Requirements for Resistance to Penicillins and Cephalosporins  

Microsoft Academic Search

Received 14 November 2001\\/Returned for modification 16 March 2002\\/Accepted 26 July 2002 Site saturation mutagenesis of the 238 position in the SHV -lactamase was performed to identify the complete sequence requirements needed for the extended spectrum -lactamase (ESBL) phenotype. MICs (in micrograms per milliliter) in an isogenic background, Escherichia coli DH10B, demonstrated that the Gly238Ala mutation conferred the most resistance

Andrea M. Hujer; Kristine M. Hujer; Marion S. Helfand; Vernon E. Anderson; R. A. Bonomo

2002-01-01

258

The Component Combined Amino Acids of Some Marine Phytoplankton Species  

Microsoft Academic Search

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

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

1967-01-01

259

Characterization of neutral amino acid transport in a marine pseudomonad.  

PubMed Central

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

Fein, J E; MacLeod, R A

1975-01-01

260

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

PubMed

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

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

2012-02-20

261

Prebiotic Synthesis of Hydrophobic and Protein Amino Acids  

PubMed Central

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

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

1972-01-01

262

Analysis of amino acid isotopomers using FT-ICR MS.  

PubMed

Fluxes through known metabolic pathways and the presence of novel metabolic reactions are often determined by feeding isotopically labeled substrate to an organism and then determining the isotopomer distribution in amino acids in proteins. However, commonly used techniques to measure the isotopomer distributions require derivatization prior to analysis (gas chromatography/mass spectrometry (GC/MS)) or large sample sizes (nuclear magnetic resonance (NMR) spectroscopy). Here, we demonstrate the use of Fourier transform-ion cyclotron resonance mass spectrometry with direct infusion via electrospray ionization to rapidly measure the amino acid isotopomer distribution in a biomass hydrolysate of the soil bacterium Desulfovibrio vulgaris Hildenborough. By applying high front-end resolution for the precursor ion selection followed by sustained off-resonance irradiation collision-induced dissociation, it was possible to determine exactly and unambiguously the specific locations of the labeled atoms in the amino acids, which usually requires a combination of 2-D 13C NMR spectroscopy and GC/MS. This method should be generally applicable to all biomass samples and will allow more accurate determination of metabolic fluxes with less work and less sample. PMID:17305312

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

2007-02-17

263

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

NASA Astrophysics Data System (ADS)

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

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

2002-11-01

264

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

PubMed Central

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

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

2004-01-01

265

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

266

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

PubMed Central

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

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

2012-01-01

267

Transport of Aromatic Amino Acids by Pseudomonas aeruginosa  

PubMed Central

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

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

1971-01-01

268

Amino acids as chiral selectors in enantioresolution by liquid chromatography.  

PubMed

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

Bhushan, Ravi; Dixit, Shuchi

2012-06-25

269

Some Factors Which Affect Amino Acid Uptake by Saccharomyces carlsbergensis  

PubMed Central

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

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

1971-01-01

270

Lipid-Amino Acid Conjugates and Methods of Use.  

National Technical Information Service (NTIS)

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

R. B. Zurier S. H. Burstein

2005-01-01

271

Protein engineering with unnatural amino acids.  

PubMed

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

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

2013-07-05

272

Synthesis of alpha-amino acids  

DOEpatents

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

Davis, J.W. Jr.

1983-01-25

273

Coherent manipulation of free amino acids fluorescence.  

PubMed

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

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

2012-03-06

274

Inhibitors of D-amino acid oxidase  

US Patent & Trademark Office Database

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

2011-03-08

275

A new synthetic protocol for coumarin amino acid  

PubMed Central

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

Xu, Xinyi

2013-01-01

276

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

Microsoft Academic Search

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

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

1999-01-01

277

Which Amino Acids Should Be Used in Prebiotic Chemistry Studies?  

Microsoft Academic Search

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

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

2008-01-01

278

Chiral Analysis of Amino Acids Using Electrochemical Composite Bienzyme Biosensors  

Microsoft Academic Search

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

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

2001-01-01

279

Amino acid transport in the renal proximal tubule  

Microsoft Academic Search

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

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

2000-01-01

280

Nutritionally essential amino acids and metabolic signaling in aging.  

PubMed

Aging is associated with a gradual decline in skeletal muscle mass and strength leading to increased risk for functional impairments. Although basal rates of protein synthesis and degradation are largely unaffected with age, the sensitivity of older muscle cells to the anabolic actions of essential amino acids appears to decline. The major pathway through which essential amino acids induce anabolic responses involves the mammalian target of rapamycin (mTOR) Complex 1, a signaling pathway that is especially sensitive to regulation by the branched chain amino acid leucine. Recent evidence suggests that muscle of older individuals require increasing concentrations of leucine to maintain robust anabolic responses through the mTOR pathway. While the exact mechanisms for the age-related alterations in nutritional signaling through the mTOR pathway remain elusive, there is increasing evidence that decreased sensitivity to insulin action, reductions in endothelial function, and increased oxidative stress may be underlying factors in this decrease in anabolic sensitivity. Ensuring adequate nutrition, including sources of high quality protein, and promoting regular physical activity will remain among the frontline defenses against the onset of sarcopenia in older individuals. PMID:23239011

Dillon, E Lichar

2012-12-14

281

Arginine: new and exciting developments for an "old" amino acid.  

PubMed

Arginine (2-amino-5-guanidino pentanoic acid) was shown in 1895 by Hedin to be present in the proteins of horn. Metabolic nitrogen balance studies, conducted in 1957 by Rose in human adults and in 1959 by Snyderman and coworkers in young infants revealed that a dietary source of this amino acid was not an obligatory requirement for growth and maintenance of nitrogen homeostasis in healthy individuals. Hence, it was initially classified as a non-essential (dispensable) amino acid and, perhaps, for reasons of this classification arginine did not receive the earlier attention it now deserves, in relation to an understanding of the nutritional biochemistry and physiology of its metabolism in humans subjects. However, there is currently a considerable interest in the cellular and tissue functions, as well as clinical, therapeutic significance, of arginine. In this paper we review the multiple functions of arginine, including its role in the L-arginine-nitric oxide pathway, cellular regeneration, immune function, protein synthesis and protein breakdown. We then consider some in vivo aspects of the physiology of arginine metabolism, which varies greatly among eukaryotes, with particular reference to humans. Against this background, studies of arginine in the nutrition of humans under various pathophysiological conditions are reviewed briefly. Finally, a new, updated concept for the metabolic basis for the "conditional essentiality" of arginine is proposed. PMID:8886345

Beaumier, L; Castillo, L; Yu, Y M; Ajami, A M; Young, V R

1996-09-01

282

Analysis of Amino Acid Isotopomers using FT-ICR MS  

SciTech Connect

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

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

2006-10-08

283

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

284

The amino acid sequence of wood duck lysozyme.  

PubMed

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

Araki, T; Torikata, T

1999-01-01

285

Which Amino Acids Should Be Used in Prebiotic Chemistry Studies?  

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

286

Recent advances in microchip electrophoresis for amino acid analysis.  

PubMed

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

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

2013-02-24

287

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

PubMed

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

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

2013-06-10

288

Protein and amino acid metabolism and requirements  

Technology Transfer Automated Retrieval System (TEKTRAN)

Proteins are the major structural and functional components of all cells of the body. Enzymes, membrane carriers, blood transport molecules, intracellular matrix, and even hair and fingernails are proteins, as are many hormones. Proteins also constitute a major portion of all membranes, and the cons...

289

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

PubMed Central

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

Verbeke, R.; Peeters, G.

1965-01-01

290

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

Microsoft Academic Search

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

K.-D. Jung; U. Lüttge

1980-01-01

291

Amino acid fermentation at the origin of the genetic code  

PubMed Central

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

2012-01-01

292

Abc Amino Acids: Design, Synthesis, and Properties of New Photoelastic Amino Acids  

SciTech Connect

Photoisomerizable amino acids provide a direct avenue to the experimental manipulation of bioactive polypeptides, potentially allowing real-time, remote control of biological systems and enabling useful applications in nanobiotechnology. Herein, we report a new class of photoisomerizable amino acids intended to cause pronounced expansion and contraction in the polypeptide backbone, i.e., to be photoelastic. These compounds, termed Abc amino acids, employ a photoisomerizable azobiphenyl chromophore to control the relative disposition of aminomethyl and carboxyl substituents. Molecular modeling of nine Abc isomers led to the identification of one with particularly attractive properties, including the ability to induce contractions up to 13A in the backbone upon transa?cis photoisomerization. This isomer, designated mpAbc, has substituents at meta and para positions on the inner (azo-linked) and outer rings, respectively. An efficient synthesis of Fmoc-protected mpAbc was executed in which the biaryl components were formed via Suzuki couplings and the azo linkage was formed via amine/nitroso condensation; protected forms of three other Abc isomers were prepared similarly. A decapeptide incorporating mpAbc was synthesized by conventional solid-phase methods and displayed characteristic azobenzene photochemical behavior with optimal conversion to the cis isomer at 360 nm and a thermal cisa?trans half life of 100 min. at 80 AoC.

Standaert, Robert F [ORNL; Park, Dr Seung Bum [Seoul National University

2006-01-01

293

Amino Acid Transport Mechanisms in Mouse Oocytes During Growth and Meiotic Maturation1  

PubMed Central

Amino acids are transported into cells by a number of different transport systems, each with their own specific range of substrates. The amino acid transport systems active in preimplantation embryos and the amino acids required by embryos for optimal development have been extensively investigated. Much less is known about amino acid transport systems active in growing and meiotically maturing oocytes or about developmental changes in their activity. As a first step in determining the array of amino acid transporters active in oocytes, the transport characteristics of nine amino acids were measured in small, medium, and large growing oocytes; in fully grown germinal vesicle (GV)-stage oocytes; in metaphase I oocytes; and in metaphase II eggs. Whether each of 11 classically defined amino acid transport systems was likely active in oocytes at each stage was determined using assays based on measuring the transport of radiolabeled amino acids into oocytes and the effect of a limited set of potential competitive inhibitors. Six amino acid transport systems were found to be active during oocyte growth or maturation. L, b0,+, and ASC/asc were active throughout oocyte growth and maturation, increasing during growth. In contrast, GLY, beta, and xc? had little or no activity during growth but became activated during meiotic maturation. Surprisingly, the presence of follicular cells surrounding medium growing oocytes or cumulus cells surrounding GV oocytes did not confer amino acid transport by additional transport systems not present in the oocyte. In some cases, however, follicular cells coupled to the oocyte enhanced uptake of amino acids by the same systems present in the oocyte.

Pelland, Amelie M.D.; Corbett, Hannah E.; Baltz, Jay M.

2009-01-01

294

Two amino acid residues determine the low substrate affinity of human cationic amino acid transporter-2A.  

PubMed

Mammalian cationic amino acid transporters (CAT) differ in their substrate affinity and sensitivity to trans-stimulation. The apparent Km values for cationic amino acids and the sensitivity to trans-stimulation of CAT-1, -2B, and -3 are characteristic of system y+. In contrast, CAT-2A exhibits a 10-fold lower substrate affinity and is largely independent of substrate at the trans-side of the membrane. CAT-2A and -2B demonstrate such divergent transport properties, even though their amino acid sequences differ only in a stretch of 42 amino acids. Here, we identify two amino acid residues within this 42-amino acid domain of the human CAT-2A protein that are responsible for the apparent low affinity of both the extracellular and intracellular substrate-binding sites. These residues are located in the fourth intracellular loop, suggesting that they are not part of the translocation pathway. Rather, they may be responsible for the low affinity conformation of the substrate-binding sites. The sensitivity to trans-stimulation is not determined by the same amino acid residues as the substrate affinity and must involve a more complex interaction between individual amino acid residues. In addition to the 42-amino acid domain, the adjacent transmembrane domain X seems to be involved in this function. PMID:12637504

Habermeier, Alice; Wolf, Sabine; Martiné, Ursula; Gräf, Petra; Closs, Ellen I

2003-03-12

295

Amino acid composition and antioxidant capacity of Spanish honeys.  

PubMed

The amino acid composition of 53 honey samples from Spain, consisting of 39 floral, 5 honeydew, and 9 blend honeys, has been determined. Physicochemical characteristics, polyphenolic content, amino acid composition, and estimation of the radical scavenging capacity against the stable free radical DPPH of the honey samples were analyzed. The resulting data have been statistically evaluated. The results showed that pH, acidity, net absorbance, electrical conductivity, and total polyphenolic contents of the honeys showed a strong correlation with the radical scavenging capacity. The correlation between the radical scavenging capacity of honey and amino acid contents was high with 18 of the 20 amino acids detected, with correlation values higher than those obtained for polyphenolic content. These results suggest that the amino acid composition of honey is an indicator of the sample's scavenging capacity. PMID:17227066

Pérez, Rosa Ana; Iglesias, María Teresa; Pueyo, Encarnación; Gonzalez, Montserrat; de Lorenzo, Cristina

2007-01-24

296

Free amino acids in botanicals and botanical preparations.  

PubMed

Numerous studies were carried out about aminoacidic composition of vegetable proteins, but information about the free amino acid pool and the role of these substances is very incomplete. The aim of this paper was to contribute to the scarce knowledge concerning the composition of free amino acids in botanicals and botanical preparations widely used as food, in dietary supplements, and in pharmaceutical products. This work studied the composition of free amino acids, identified the major components of 19 species of plants, and evaluated the influence of different types of extraction on the amino acid profile. Amino acids were determined using an automatic precolumn derivatization with fluorenylmethyl-chloroformate and reversed-phase liquid chromatography with fluorescence and ultraviolet detection. The amounts of total free amino acids varied widely between plants, from approximately 12 g in 100 g of Echinacea pallida extract to less than 60 mg in the same amount of Coleus forskohlii, Garcinia cambogia, and Glycine max. In 13 plants arginine, asparagine, glutamine, proline, and gamma-aminobutyric acid were the free amino acids found in preponderant quantities. The levels of free amino acids above the quantification limit in 36 assayed samples of botanicals, extracts, and supplements are shown. PMID:18576976

Carratù, B; Boniglia, C; Giammarioli, S; Mosca, M; Sanzini, E

2008-06-01

297

Survival of Amino Acids in Micrometeorites During Atmospheric Entry  

NASA Astrophysics Data System (ADS)

The delivery of amino acids by micrometeorites to the early Earth during the period of heavy bombardment could have been a significant source of the Earth's prebiotic amino acid inventory provided that these organic compounds survived atmospheric entry heating. To investigate the sublimation of amino acids from a micrometeorite analog at elevated temperature, grains from the CM-type carbonaceous chondrite Murchison were heated to 550°C inside a glass sublimation apparatus (SA) under reduced pressure. The sublimed residue that had collected on the cold finger of the SA after heating was analyzed for amino acids by HPLC. We found that when the temperature of the meteorite reached ~150°C, a large fraction of the amino acid glycine had vaporized from the meteorite, recondensed onto the end of the SA cold finger, and survived as the rest of the grains heated to 550°C. ?-Aminoisobutryic acid and isovaline, which are two of the most abundant non-protein amino acids in Murchison, did not sublime from the meteorite and were completely destroyed during the heating experiment. Our experimental results suggest that sublimation of glycine present in micrometeorite grains may provide a way for this amino acid to survive atmospheric entry heating at temperatures >550°C; all other amino acids apparently are destroyed.

Glavin, Daniel P.; Bada, Jeffrey L.

2001-09-01

298

A fatty acid synthase gene in Cochliobolus carbonum required for production of HC-toxin, cyclo(D-prolyl-L-alanyl-D-alanyl-L-2-amino-9, 10-epoxi-8-oxodecanoyl).  

PubMed

The fungal maize pathogen Cochliobolus carbonum produces a phytotoxic and cytostatic cyclic peptide, HC-toxin, of structure cyclo(D-prolyl-L-alanyl-D-alanyl-L-Aeo), in which Aeo stands for 2-amino-9,10-epoxi-8-oxodecanoic acid. Here we report the isolation of a gene, TOXC, that is present only in HC-toxin-producing (Tox2+) fungal strains. TOXC is present in most Tox2+ strains in three functional copies, all of which are on the same chromosome as the gene encoding HC-toxin synthetase. When all copies of TOXC are mutated by targeted gene disruption, the fungus grows and sporulates normally in vitro but no longer makes HC-toxin and is not pathogenic, indicating that TOXC has a specific role in HC-toxin production and hence virulence. The TOXC mRNA is 6.5 kb and the predicted product has 2,080 amino acids and a molecular weight of 233,000. The primary amino acid sequence is highly similar (45 to 47% identity) to the beta subunit of fatty acid synthase from several lower eukaryotes, and contains, in the same order as in other beta subunits, domains predicted to encode acetyl transferase, enoyl reductase, dehydratase, and malonyl-palmityl transferase. The most plausible function of TOXC is to contribute to the synthesis of the decanoic acid backbone of Aeo. PMID:9057326

Ahn, J H; Walton, J D

1997-03-01

299

[Complications due to receiving incorrect amino acid preparations].  

PubMed

Due to improved diagnostics and care there is an increasing number of adults with inherited metabolic diseases. The best-known example is phenylketonuria. Treatment consists of a disease-specific diet, for example protein restriction supplemented with essential amino acids. However, like prescription drugs, diet preparations can have side effects. This implies that a description of the indications and contra-indications, an assessment of the efficacy and a definition of the desired duration of treatment are required. Mistakes in the delivery of these disease-specific diet preparations by the pharmacy can have severe consequences, as illustrated by three case reports. PMID:23328017

van der Wiel, Adoree M; Janssen, Mirian C H; Hollack, Carla E M; Langendonk, Janneke G

2013-01-01

300

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

SciTech Connect

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

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

2007-02-14

301

A net carbohydrate and protein system for evaluating cattle diets: IV. Predicting amino acid adequacy.  

PubMed

The Cornell Net Carbohydrate and Protein System was modified to include an amino acid submodel for predicting the adequacy of absorbed essential amino acids in cattle diets. Equations for predicting the supply of and requirements for absorbed essential amino acids are described and presented. The model was evaluated for its ability to predict observed duodenal flows of nitrogen, nonammonia nitrogen, bacterial nitrogen, dietary nonammonia nitrogen, and individual essential amino acids. Model-predicted nitrogen, nonammonia nitrogen, bacterial nitrogen, and dietary nonammonia nitrogen explained 93.2, 94.6, 76.4, and 79.3% of the observed duodenal flows, respectively, based on R2 values from predicted vs observed regression analysis. Based on slopes of regression lines, model-predicted duodenal nitrogen and nonammonia nitrogen were different from observed duodenal flows (P < .05), whereas model-predicted bacterial nitrogen and dietary nonammonia nitrogen were not different from observed duodenal flows (P < .05). Model-predicted duodenal flows of individual essential amino acids explained 81 to 90% of variation in observed duodenal amino acid flows. Based on slopes of regression lines, model-predicted duodenal threonine, leucine, and arginine were the only amino acids different from observed duodenal flows (P < .05). Ideas for further model improvements and research in amino acid metabolism were also presented. PMID:8505261

O'Connor, J D; Sniffen, C J; Fox, D G; Chalupa, W

1993-05-01

302

Mechanistic Pathways of Formation of Acrylamide from Different Amino Acids  

Microsoft Academic Search

Studies on model systems of amino acids and sugars have indicated that acrylamide can be generated from asparagine or from amino acids that can produce acrylic acid either directly such as ?-alanine, aspartic acid and carnosine or indirectly such as cysteine and serine. The main pathway specifically involves asparagine and produces acrylamide directly after a sugar-assisted decarboxylation and 1,2-elimination steps

Varoujan A. Yaylayan; Carolina Perez Locas; Andrzej Wnorowski; John O’Brien

303

Thin-Layer Chromatography of Dansyl Amino Acids on Polyamide  

Microsoft Academic Search

Summary Thin-Layer Chromatography of Dansyl Amino Acids on Polyamide A two-dimensional thin-layer chromatography system for the separation of the dansyl derivatives of the amino acids commonly found in proteins is described. Chromatography was performed on polyamide sheets using water-pyridine-formic acid (93:3.5:3.5 v\\/v) and benzene-acetic acid (4.5:1 v\\/v) as the solvents.

James C. Wesenberg; R. J. Thibert

1977-01-01

304

Molecular regulation of amino acid biosynthesis in plants  

Microsoft Academic Search

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

B. K. Singh; B. F. Matthews

1994-01-01

305

Clearance of amino acids by hemodialysis in argininosuccinate synthetase deficiency  

Microsoft Academic Search

We determined the dialytic clearance of amino acids involved in ammoniagenesis and nitrogen excretion in a neonate with argininosuccinate synthetase deficiency who underwent acute hemodialysis. Plasma ammonia and plasma and dialysate amino acid concentrations were obtained at baseline, 30-minute intervals during hemodialysis, and 30 minutes after the completion of hemodialysis. Plasma ammonia concentrations declined by 56% during the 90-minute hemodialysis

Kevin D. McBryde; Timothy L. Kudelka; David B. Kershaw; Patrick D. Brophy; John J. Gardner; William E. Smoyer

2004-01-01

306

Amino Acid Metabolism in the Griseofulvin Producer 'Pen. nigricans Thom'.  

National Technical Information Service (NTIS)

A total of 18 amino acids were detected in the mycelium of P. nigricans. Predominant among these were glutamic acid (38.9 mg per gram of dry mycelium), proline (30.15 mg), and histidine (28.42 mg). In addition a high content of the amino sugar glucosamine...

T. P. Efimova

1974-01-01

307

?-Vinylic amino acids: occurrence, asymmetric synthesis, and biochemical mechanisms  

Microsoft Academic Search

This report presents an overview of the family of naturally occurring ‘vinylic’ amino acids, namely those that feature a C–C double bond directly attached to the ?-carbon, along the side chain. Strategies that have been brought to bear on the stereocontrolled synthesis of these olefinic amino acids are surveyed. The mechanistic diversity by which such ‘vinylic triggers’ can be actuated

David B. Berkowitz; Bradley D. Charette; Kannan R. Karukurichi; Jill M. McFadden

2006-01-01

308

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

309

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

NASA Astrophysics Data System (ADS)

We analyzed the amino acid composition of a fragment of the Sutter's Mill meteorite (SM2) using liquid chromatography time of flight mass spectrometry. In contrast to other CM meteorites, only trace levels of amino acids were detected in SM2.

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

2012-09-01

310

Factors Affecting Circadian Periodicity of Blood Amino Acids in Man.  

National Technical Information Service (NTIS)

Total whole blood amino acids in normal men and all major individual blood amino acids (with the single exception of citrulline) were found to display a circadian periodicity characterized by peak values between 1200 and 2000 hours and lowest values betwe...

R. D. Feigin A. S. Klainer W. R. Beisel

1968-01-01

311

The Amino Acid Sequence of beta Galactosidase of Escherichia coli  

Microsoft Academic Search

The amino acid sequence of beta -galactosidase was determined. The protein contains 1021 amino acid residues in a single polypeptide chain. The subunit molecular weight calculated from the sequence is 116,248. The sequence determination, carried out mainly by conventional methods, was aided by complementation tests, by the use of termination mutant strains, and by a new immunochemical method. The five

Audree V. Fowler; Irving Zabin

1977-01-01

312

Biological activity of amino acids in organotypic tissue cultures.  

PubMed

We studied the effect of 20 standard L-amino acids on proliferation of the nervous, cardiovascular, urogenital, digestive, and immune system tissues from young and old animals in organotypic cultures. The effect of amino acids on tissue culture proliferation depended on their origin and animal age. PMID:24143390

Chalisova, N I; Kontsevaya, N E; Linkova, N S; Pronyaeva, V E; Chervyakova, N A; Umnov, R S; Benberin, V V; Khavinson, V H

2013-07-01

313

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...

314

Synthesis and Characterization of Novel Bi and Tricyclic ?-Amino Acids  

Microsoft Academic Search

As part of a medicinal chemistry collaboration, a number of novel bi- and tricyclic ?-amino acids were prepared through various routes and characterized by H nuclear Overhauser effect difference experiments. The syntheses provide a number of routes to access some highly substituted amino acid derivatives that have not been reported previously. It is envisaged that the chemistry described here could

Matthew R. Johnson; Jolicia F. Gauuan; Cheng Guo; Peter R. Guzzo; Van-Duc Le; Rajesh A. Shenoy; James Hamby; Howard Roark; Michael Stier; John E. Mangette

2011-01-01

315

Conserved amino acid markers from past influenza pandemic strains  

Microsoft Academic Search

BACKGROUND: Finding the amino acid mutations that affect the severity of influenza infections remains an open and challenging problem. Of special interest is better understanding how current circulating influenza strains could evolve into a new pandemic strain. Influenza proteomes from distinct viral phenotype classes were searched for class specific amino acid mutations conserved in past pandemics, using reverse engineered linear

Jonathan E Allen; Shea N Gardner; Elizabeth A Vitalis; Tom R Slezak

2009-01-01

316

Single amino acid replacements affecting the thermostability of kanamycin nucleotidyltransferase  

Microsoft Academic Search

Amino acid residues of the carboxyl-terminal region of kanamycin nucleotidyltransferase were modified using segment-directed mutagenesis. Six different mutant enzymes with single amino acid replacements were selected out of 59 clones by DNA sequence analyses. The mutant enzymes were purified and it was found that the thermostability of one mutant enzyme was identical to the wild type, whereas the other five

Masazumi Matsumura; Shiro Kataoka; Shuichi Aiba

1986-01-01

317

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

318

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

319

Highly enantioselective synthesis of a fluorescent amino acid  

Microsoft Academic Search

A high enantiomeric excess (>99.5%) synthesis of l-2-amino-3-(7-methoxy-4-coumaryl) propionic acid (l-Amp) is described. The two step synthesis route of this non-proteinogenic amino acid includes an oxazinone derivative as glycine enolate, which is alkylated with the fluorogenic group.

Péter Kele; Guodong Sui; Qun Huo; Roger M. Leblanc

2000-01-01

320

Genetic code correlations: Amino acids and their anticodon nucleotides  

Microsoft Academic Search

Summary The data here show direct correlations between both the hydrophobicity and the hydrophilicity of the homocodonic amino acids and their anticodon nucleotides. While the differences between properties of uracil and cytosine derivatives are small, further data show that uracil has an affinity for charged species. Although these data suggest that molecular relationships between amino acids and anticodons were responsible

A. L. Weber; J. C. Lacey

1978-01-01

321

Subcritical water extraction of amino acids from Atacama Desert soils  

Microsoft Academic Search

(1) Amino acids are considered organic molecular indicators in the search for extant and extinct life in the Solar System. Extraction of these molecules from a particulate solid matrix, such as Martian regolith, will be critical to their in situ detection and analysis. The goals of this study were to optimize a laboratory amino acid extraction protocol by quantitatively measuring

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

2007-01-01

322

Subcritical water extraction of amino acids from Atacama Desert soils  

Microsoft Academic Search

Amino acids are considered organic molecular indicators in the search for extant and extinct life in the Solar System. Extraction of these molecules from a particulate solid matrix, such as Martian regolith, will be critical to their in situ detection and analysis. The goals of this study were to optimize a laboratory amino acid extraction protocol by quantitatively measuring the

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

2007-01-01

323

Amino acid metabolism in nongrowing environments in higher plants  

Microsoft Academic Search

During winter season, growth of biennial and perennial plants was virtually halted. Amino acid analyses of 74 samples of woody and herbaceous plants including grasses and winter wheat showed following results. In innately dormant plants, synthesis and accumulation of free amino acids were completed in fall and next changes occurred in the following spring. In plants under enforced dormancy, a

S. Sagisaka

1993-01-01

324

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...

325

A modular synthesis of dithiocarbamate pendant unnatural ?-amino acids.  

PubMed

Unnatural ?-amino acids containing dithiocarbamate side chains were synthesized by a one-pot reaction of in situ generated dithiocarbamate anions with sulfamidates. A wide range of these anions participated in the highly regio- and stereo-selective ring opening of sulfamidates to produce the corresponding dithiocarbamate pendant ?-amino acids in high yields. PMID:22814637

Saha, Amit; Baig, R B Nasir; Leazer, John; Varma, Rajender S

2012-07-20

326

Boron containing amino acid compounds and methods for their use  

DOEpatents

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

Glass, John D. (Shoreham, NY); Coderre, Jeffrey A. (Wading River, NY)

2000-01-01

327

Renal handling of amino acids in 5\\/6-nephrectomized rats: Stimulation of renal amino acid reabsorption after treatment with triiodothyronine or dexamethasone under amino acid load  

Microsoft Academic Search

Summary In anaesthetized adult female rats, the renal amino acid handling was measured six days after 5\\/6 nephrectomy (5\\/6NX). The distinct rise in blood urea nitrogen as well as the significant reduction in urine flow and GFR indicate an impairment of kidney function. In principle, in 5\\/6NX rats amino acid plasma concentrations were comparable to those of control animals with

Ch. Fleck; K. Gräfe; I. Kart

1999-01-01

328

Dietary sulfur amino acid modulation of cysteine sulfinic acid decarboxylase.  

PubMed

Male rats were fed sulfur and nonsulfur amino acid-supplemented diets, and the response of cysteine sulfinic acid decarboxylase (CSAD) activity was determined. After adaptation to a casein-based basal diet, rats were fed diets containing additions of L-methionine. Hepatic CSAD activity decreased in a dose-dependent manner. Significant depression of CSAD activity in liver was evident within 24 h of feeding rats a methionine-supplemented diet. Depression of enzyme activity was reversed upon refeeding the basal diet. After rats were fed diets supplemented with methionine, cystine, homocystine, S-methyl-L-cysteine, phenylalanine, leucine, or ethionine for 14 days, hepatic CSAD activity in rats fed S-methyl-L-cysteine-, phenylalanine-, or leucine-supplemented diets was not depressed compared with activity in rats fed a basal diet. In contrast, CSAD activity in livers of rats fed cystine-, homocystine-, methionine-, or ethionine-supplemented diets was 60, 40, 40, and 8%, respectively, of the activity in livers from control rats. Immunochemical detection and quantification of CSAD protein in rat liver indicated that CSAD protein concentration was correlated to CSAD activity. CSAD activity may be specifically regulated by sulfur amino acids metabolized by the S-adenosylmethionine-dependent pathway of methionine metabolism. PMID:1951678

Jerkins, A A; Steele, R D

1991-11-01

329

Serotonin and amino acids: partners in delirium pathophysiology?  

PubMed

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

van der Mast, R C; Fekkes, D

2000-04-01

330

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

PubMed Central

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

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

1945-01-01

331

Synthesis of amino acids by arc-discharge experiments  

NASA Astrophysics Data System (ADS)

Discharge was performed against ammonia water using a graphite rod as the anode and a silver thread as the cathode under an Ar atmosphere. HPLC and thin layer chromatograph (TLC) analyses showed that three kinds of amino acids were produced in the reaction mixture. As the graphite anode is the solitary source of carbon in the system, it is considered that amino acids have been produced by synthetic reaction between graphite and ammonia water. Thus, our results provide a possible way of formation of amino acids from elemental carbon on the primitive earth. In addition, the mechanism for the production of amino acids is discussed and the yields of different amino acids are presented.

Huaibin, S.; Chunlin, S.; Zengliang, Y.

2001-10-01

332

Peptide and amino acid separation with nanofiltration membranes  

SciTech Connect

Several nanofiltration membranes [UTC-20, 60 (Toray Industries), NF-40 (Film-Tech Corporation), Desal-5, G-20 (Desalination Systems), and NTR-7450 (Nitto Electric Industrial Co.)] were applied to separate amino acids and peptides on the basis of charge interaction with the membranes since most of them contain charged functional groups. Nanofiltration membranes having a molecular weight cutoff (MWCO) below 300 (UTC-20, 60, NF-40 and Desal-5) were not suitable for separation of amino acids. On the other hand, separation of amino acids and peptides with nanofiltration membranes having a MWCO around 2000-3000 (NTR-7450 and G-20) was satisfactory based on a charge effect mechanism; charged amino acids and peptides were rejected while neutral amino acids and peptides permeated through the membranes. Separation of peptides having different isoelectric points with nanofiltration membranes was possible by adjusting the pH. 15 refs., 11 figs., 4 tabs.

Tsuru, Toshinori; Shutou, Takatoshi; Nakao, Shin-Ichi; Kimura, Shoji (Univ. of Tokyo (Japan))

1994-05-01

333

Genetically encoding unnatural amino acids for cellular and neuronal studies  

PubMed Central

Proteins participate in various biological processes and can be harnessed to probe and control biological events selectively and reproducibly, but the genetic code limits the building block to 20 common amino acids for protein manipulation in living cells. The genetic encoding of unnatural amino acids will remove this restriction and enable new chemical and physical properties to be precisely introduced into proteins. Here we present new strategies for generating orthogonal tRNA-synthetase pairs, which made possible the genetic encoding of diverse unnatural amino acids in different mammalian cells and primary neurons. Using this new methodology, we incorporated unnatural amino acids with extended side chains into the K+ channel Kv1.4, and found that the bulkiness of residues in the inactivation peptide is essential for fast channel inactivation, a finding that had not been possible using conventional mutagenesis. This technique will stimulate and facilitate new molecular studies using tailored unnatural amino acids for cell biology and neurobiology.

Wang, Wenyuan; Takimoto, Jeffrey K; Louie, Gordon V; Baiga, Thomas J; Noel, Joseph P; Lee, Kuo-Fen; Slesinger, Paul A; Wang, Lei

2009-01-01

334

Wet, Carbonaceous Asteroids: Altering Minerals, Changing Amino Acids  

NASA Astrophysics Data System (ADS)

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

Taylor, G. J.

2011-04-01

335

Cloud droplet activation of amino acid aerosol particles.  

PubMed

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

Kristensson, Adam; Rosenørn, Thomas; Bilde, Merete

2010-01-14

336

Amino Acid Challenge in Patients with Cirrhosis and Control Subjects: Ammonia, Plasma Amino Acid and EEG Changes  

Microsoft Academic Search

Background\\/aims: The pathogenesis of hepatic encephalopathy (HE) is controversial. We have therefore studied the effect of induced hyperammonaemia in man. Patients and methods: 108 g of an amino acid mixture was given orally to 18 cirrhotics and 11 control subjects and changes in blood ammonia, EEG and plasma amino acids were observed. Results: Basal (39±6 versus 14±2 ?mol\\/l) and 120-min post amino

Hanan Al Mardini; Andrew Douglass; Christopher Record

2006-01-01

337

Interaction of dipropyltin(IV) with amino acids, peptides, dicarboxylic acids and DNA constituents  

Microsoft Academic Search

Interaction of dipropyltin(IV) with selected amino acids, peptides, dicarboxylic acids or DNA constituents was investigated using potentiometric techniques. Amino acids form 1?:?1 and 1?:?2 complexes and, in some cases, protonated complexes. The amino acid is bound to dipropyltin(IV) by the amino and carboxylate groups. Serine is complexed to dipropyltin(IV) with ionization of the alcoholic group. A relationship exists between the

A. A. Al-Najjar; M. M. A. Mohamed; M. M. Shoukry

2006-01-01

338

Formation of Amino Acids from Reactor Irradiated Ammonium Acetate  

NASA Astrophysics Data System (ADS)

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

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

1982-12-01

339

[Revision of the structure of ristomycinic and actinoidinic amino acids].  

PubMed

The structures of ristomycin and actinoidine amino acids described earlier were revised. Crystalline derivatives of the amino acids and the products of their oxidation were prepared. The study on the spectral properties of the compounds showed that ristomycin and actinoidine amino acids had the structures of 3-(2'-hydroxy-5'-glycyl-phenoxy)-4-methyl-5-hydroxyphenylglycine and 2-(2'-hydroxy-5'-glycyl-phenyl)-3,5-dioxyphenylglycine respectively. They did not differ from deaminodicarboxylic acids prepared with ristocetin, vancomycin and actionoidine. PMID:6271043

Lomakina, N N; Tokareva, N L; Berdnikova, T F; Potapova, N P; Terent'ev, P B

1981-08-01

340

INFLUENCE OF DIETARY AMINO ACID SUPPLE MENTS ON THE FREE AMINO ACIDS IN THE BLOOD PLASMA OF CHICKS  

Microsoft Academic Search

In a survey of the effect of the dietary level of vitamins on the free amino acids in the plasma of chicks, Richardson, Blaylock and Lyman ('53) found that some of the free amino acids were present in smaller amounts with a low level of intake of some vitamins and higher with a low level of other vitamins. Heir ('47)

LUTHER B. EICHARDSON; LYNN G. BLAYLOCK; CARL M. LYMAN

341

37 CFR 1.824 - Form and format for nucleotide and/or amino acid sequence submissions in computer readable form.  

Code of Federal Regulations, 2013 CFR

...and/or amino acid sequence submissions in computer readable form. 1.824 Section 1.824...and/or amino acid sequence submissions in computer readable form. (a) The computer readable form required by §...

2013-07-01

342

Amino Acid Catabolism by an areA-Regulated Gene Encoding an l-Amino Acid Oxidase with Broad Substrate Specificity in Aspergillus nidulans  

PubMed Central

The filamentous fungus Aspergillus nidulans can use a wide range of compounds as nitrogen sources. The synthesis of the various catabolic enzymes needed to breakdown these nitrogen sources is regulated by the areA gene, which encodes a GATA transcription factor required to activate gene expression under nitrogen-limiting conditions. The areA102 mutation results in pleiotropic effects on nitrogen source utilization, including better growth on certain amino acids as nitrogen sources. Mutations in the sarA gene were previously isolated as suppressors of the strong growth of an areA102 strain on l-histidine as a sole nitrogen source. We cloned the sarA gene by complementation of a sarA mutant and showed that it encodes an l-amino acid oxidase enzyme with broad substrate specificity. Elevated expression of this enzyme activity in an areA102 background accounts for the strong growth of these strains on amino acids that are substrates for this enzyme. Loss of function sarA mutations, which abolish the l-amino acid oxidase activity, reverse the areA102 phenotype. Growth tests with areA102 and sarA mutants show that this enzyme is the primary route of catabolism for some amino acids, while other amino acids are metabolized through alternative pathways that yield either ammonium or glutamate for growth.

Davis, Meryl A.; Askin, Marion C.; Hynes, Michael J.

2005-01-01

343

Amino Acid Transport in Germinating Castor Bean Seedlings 1  

PubMed Central

During germination and early growth of the castor bean (Ricinus communis) nitrogenous constituents from the endosperm are transferred via the cotyledons to the growing embryo. Exudate collected from the cut hypocotyl of 4-day seedlings contained 120 millimolar soluble amino nitrogen and glutamine was the predominant amino acid present, comprising 35 to 40% of the total amino nitrogen. To determine the nature of nitrogen transfer, the endosperm and hypocotyl were removed and glutamine uptake by the excised cotyledons was investigated. Uptake was linear for at least 2 hours and the cotyledons actively accumulated glutamine against a concentration gradient. The uptake was sensitive to respiratory inhibitors and uncouplers and efflux of glutamine from the excised cotyledons was negligible. Transport was specific for the l-isomer. Other neutral amino acids were transported at similar rates to glutamine. Except for histidine, the acidic and basic amino acids were transported at lower rates than the neutral amino acids. For glutamine transport, the Km was 11 to 12 millimolar and the Vmax was 60 to 70 micromoles per gram fresh weight per hour. Glutamine uptake was diminished in the presence of other amino acids and the extent of inhibition was greatest for those amino acids which were themselves rapidly transported into the cotyledons. The transport of amino acids, on a per seedling basis, was greatest for cotyledons from 4-to 6-day seedlings, when transfer of nitrogen from the endosperm is also maximal. It is concluded that the castor bean cotyledons are highly active absorptive organs transporting both sucrose and amino acids from the surrounding endosperm at high rates.

Robinson, Simon P.; Beevers, Harry

1981-01-01

344

One-step amino acid selective isotope labeling of proteins in prototrophic Escherichia coli strains.  

PubMed

Amino acid selective isotope labeling is a useful approach to simplification of nuclear magnetic resonance (NMR) spectra of large proteins. Cell-free protein synthesis offers essentially unlimited flexibility of labeling patterns but is labor-intensive and expensive. In vivo labeling is simple in principle but generally requires auxotrophic strains, inhibitors of amino acid synthesis, or complex media formulations. We describe a simple procedure for amino acid selective labeling of proteins expressed in prototrophic Escherichia coli strains. Excellent labeling selectivity was achieved for histidine, lysine, methionine, and alanine. Simplicity and robustness of this protocol make it a useful tool for protein NMR. PMID:22538396

O'Grady, Christopher; Rempel, Benjamin L; Sokaribo, Akosiererem; Nokhrin, Sergiy; Dmitriev, Oleg Y

2012-04-23

345

Aphid genome expression reveals host-symbiont cooperation in the production of amino acids  

PubMed Central

The evolution of intimate symbiosis requires the coordination of gene expression and content between the distinct partner genomes; this coordination allows the fusion of capabilities of each organism into a single integrated metabolism. In aphids, the 10 essential amino acids are scarce in the phloem sap diet and are supplied by the obligate bacterial endosymbiont (Buchnera), which lives inside specialized cells called bacteriocytes. Although Buchnera’s genome encodes most genes for essential amino acid biosynthesis, several genes in essential amino acid pathways are missing, as are most genes for production of nonessential amino acids. Additionally, it is unresolved whether the supply of nitrogen for amino acid biosynthesis is supplemented by recycling of waste ammonia. We compared pea aphid gene expression between bacteriocytes and other body tissues using RNA sequencing and pathway analysis and exploiting the genome sequences available for both partners. We found that 26 genes underlying amino acid biosynthesis were up-regulated in bacteriocytes. Seven of these up-regulated genes fill the gaps of Buchnera’s essential amino acid pathways. In addition, genes underlying five nonessential amino acid pathways lost from Buchnera are up-regulated in bacteriocytes. Finally, our results reveal that two genes, glutamine synthetase and glutamate synthase, which potentially work together in the incorporation of ammonium nitrogen into glutamate (GOGAT) cycle to assimilate ammonia into glutamate, are up-regulated in bacteriocytes. Thus, host gene expression and symbiont capabilities are closely integrated within bacteriocytes, which function as specialized organs of amino acid production. Furthermore, the GOGAT cycle may be a key source of nitrogen fueling the integrated amino acid metabolism of the aphid–Buchnera partnership.

Hansen, Allison K.; Moran, Nancy A.

2011-01-01

346

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

347

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

Microsoft Academic Search

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 ther- mophilus to produce aroma compounds from three amino acids, leucine,

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

2004-01-01

348

Amino Acid Synthesis in a Supercritical Carbon Dioxide - Water System  

PubMed Central

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

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

2009-01-01

349

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

PubMed Central

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

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

2010-01-01

350

Stereoselective synthesis of uridine-derived nucleosyl amino acids.  

PubMed

Novel hybrid structures of 5'-deoxyuridine and glycine were conceived and synthesized. Such nucleosyl amino acids (NAAs) represent simplified analogues of the core structure of muraymycin nucleoside antibiotics, making them useful synthetic building blocks for structure-activity relationship (SAR) studies. The key step of the developed synthetic route was the efficient and highly diastereoselective asymmetric hydrogenation of didehydro amino acid precursors toward protected NAAs. It was anticipated that the synthesis of unprotected muraymycin derivatives via this route would require a suitable intermediate protecting group at the N-3 of the uracil base. After initial attempts using PMB- and BOM-N-3 protection, both of which resulted in problematic deprotection steps, an N-3 protecting group-free route was envisaged. In spite of the pronounced acidity of the uracil-3-NH, this route worked equally efficient and with identical stereoselectivities as the initial strategies involving N-3 protection. The obtained NAA building blocks were employed for the synthesis of truncated 5'-deoxymuraymycin analogues. PMID:22059552

Spork, Anatol P; Wiegmann, Daniel; Granitzka, Markus; Stalke, Dietmar; Ducho, Christian

2011-11-21

351

Transaminases for the synthesis of enantiopure beta-amino acids  

PubMed Central

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

2012-01-01

352

Light chains of mouse myeloma proteins: partial amino acid sequence.  

PubMed

Five kappa chains in the urinary proteins of the BALB/c mouse have the same carboxyl terminal amino acid sequence; this sequence resembles that of kappa light chains in human immunoglobulins. The five chains have amino acid sequence variations at the amino- terminal. The genetic basis for the amino- terminal variations is not understood but could be due either to a mecha nism for differently translating a single genetic message or to the presence of more than one kappa- type structural cistron in the BALB/c genome. PMID:5917087

Perham, R; Appella, E; Potter, M

1966-10-21

353

Amino acid composition of spring wheats and losses of lysine during chapati baking  

Microsoft Academic Search

Forty-four spring wheat varieties representing 64 years of wheat cultivar releases were evaluated for amino acid composition. The concentration of several amino acids differed among the wheat varieties but amino acids did not significantly consistently among wheat varieties and growth conditions. Significant differences existed in amino acid score due to wheat varieties and crop years. The variations in amino acids

Faqir M. Anjum; Ijaz Ahmad; Masood S. Butt; M. A. Sheikh; Imran Pasha

2005-01-01

354

Taste Enhancements Between Various Amino Acids and IMP  

Microsoft Academic Search

It is well known that a strong synergistic interaction of umami occurs between L-? -amino acids with an acidic side chain, such as L-Glu or L-Asp, and 5'-mononucleotides, such as inosine 5'-monophosphate (IMP). We tested taste interactions between various L-? -amino acids and IMP by the psychophysical method and found that taste enhancement occurred when IMP was added to several

Misako Kawai; Atsushi Okiyama; Yoichi Ueda

2002-01-01

355

Gustatory responses of eel palatine receptors to amino acids and carboxylic acids  

PubMed Central

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 alpha-amino acid (alpha-alanine) and beta-amino acid (beta-alanine). (b) The threshold concentrations of the most potent amino acids (arginine, glycine) were between 10(-8) and 10(-9) M. 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(-7) M. The magnitude of the response at 10(-2) M 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 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.

1979-01-01

356

Amino acid composition of organic matter associated with carbonate and non-carbonate sediments  

Microsoft Academic Search

Amino acids comprise from 15 to 36% by weight of humic substances from carbonate and non-carbonate sediments. Humic and fulvic acids extracted from carbonate sediments are characterized by an amino acid composition consisting primarily of the acidic amino acids, aspartic and glutamic acid. Humic substances from non-carbonate sediments have a distinctly different amino acid composition consisting primarily of glycine and

Paul W. Carter; Richard M. Mitterer

1978-01-01

357

Identification of L-amino acid\\/L-lysine ?-amino oxidase in mouse brain  

Microsoft Academic Search

Lysine, an essential amino acid is catabolized in brain through only the pipecolic acid pathway. During the formation of pipecolic acid, a-deamination of lysine, and the formation of the a-keto acid as well as its cyclized product are pre-requisites. The enzyme mediated a-deamination of L-lysine and the formation of the a-keto acid and the cyclized product are not demonstrated so

S. N. Murthy; M. K. Janardanasarma

1999-01-01

358

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.

Mevi-Schutz, Jovanne; Erhardt, Andreas

2004-01-01

359

The Fate of Amino Acids During Simulated Meteoritic Impact  

NASA Astrophysics Data System (ADS)

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

Bertrand, Marylène; van der Gaast, Sjerry; Vilas, Faith; Hörz, Friedrich; Haynes, Gerald; Chabin, Annie; Brack, Andre; Westall, Frances

2009-12-01

360

Concentrations of free amino acids and other blood components in a lymphoma patient during intensive hemodialysis  

Microsoft Academic Search

L?Asparaginase is used as a therapeutic enzyme to selectively destroy asparagine?dependent cancer cells. This study explores alternate means for depriving cancer tissues of L?asparagine and other specific amino acids or vital substrates required by normal and cancer cells. Hemodialysis, employing an artificial kidney, was used to remove free amino acids from the blood of a patient with lymphoblastic lymphosarcoma. Approximately

Vernon Riley

1981-01-01

361

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

362

Influence of leucine infusion on intracellular amino acids in humans.  

PubMed

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

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

1990-06-01

363

Chiral selective transmembrane transport of amino acids through artificial channels.  

PubMed

Peptide-appended pillar[n]arene (n = 5, 6) derivatives have been synthesized. (1)H NMR and IR studies revealed that the molecules adopt a tubular conformation in solution and lipid bilayer membranes. Kinetic measurements using the fluorescent labeling method with lipid vesicles revealed that these molecules can efficiently mediate the transport of amino acids across lipid membranes at a very low channel-to-lipid ratio (EC(50) = 0.002 mol %). In several cases, chiral selectivity for amino acid enantiomers was achieved, which is one of the key functions of natural amino acid channels. PMID:23362942

Chen, Lei; Si, Wen; Zhang, Liang; Tang, Gangfeng; Li, Zhan-Ting; Hou, Jun-Li

2013-02-01

364

Uptake of Branched-Chain Amino Acids by Streptococcus thermophilus  

PubMed Central

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

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

1983-01-01

365

Amino acids as promoieties in prodrug design and development.  

PubMed

Prodrugs are biologically inactive agents that upon biotransformation in vivo result in active drug molecules. Since prodrugs might alter the tissue distribution, efficacy and the toxicity of the parent drug, prodrug design should be considered at the early stages of preclinical development. In this regard, natural and synthetic amino acids offer wide structural diversity and physicochemical properties. This review covers the use of amino acid prodrugs to improve poor solubility, poor permeability, sustained release, intravenous delivery, drug targeting, and metabolic stability of the parent drug. In addition, practical considerations and challenges associated with the development of amino acid prodrugs are also covered. PMID:23099277

Vig, Balvinder S; Huttunen, Kristiina M; Laine, Krista; Rautio, Jarkko

2012-10-22

366

Influence of crops, crop residues and manure on amino acid and amino sugar fractions of organic nitrogen in soil  

Microsoft Academic Search

A field experiment was carried out to study the effect of: (1) the cultivation of a cereal (pearl millet) and two legumes (mung bean and clusterbean), and (2) incorporation of crop residues and manure in soil, on depletion or enrichment of pools of amino acid-N and amino sugar-N in soil. Both legumes enriched amino acid and amino sugar fractions but

Praveen-Kumar; K. Tripathi; R. Aggarwal

2002-01-01

367

Study of nonenzymic browning in ?-amino acid and ?-aminobutyric acid\\/sugar model systems  

Microsoft Academic Search

The reactivities, in nonenzymic browning, of ?-aminobutyric acid (GABA), a non-protein amino acid with wide natural occurrence and potential health benefits as it occurs in foods, and of the ?-l-amino acids arginine, glutamic acid, glutamine, leucine, lysine, and phenylalanine were investigated by heating equimolar mixtures of glucose and the cited amino acids at 110°C at pH 6.0 for different times

Lieve Lamberts; Ine Rombouts; Jan A. Delcour

2008-01-01

368

Three-dimensional environment renders cancer cells profoundly less susceptible to a single amino acid starvation.  

PubMed

Increased amino acid requirement of malignant cells is exploited in metabolic antitumor therapy, e.g., enzymotherapies based on arginine or methionine deprivation. However, studies on animal models and clinical trials revealed that solid tumors are much less susceptible to single amino acid starvation than could be expected from the in vitro data. We conducted a comparative analysis of the response of several tumor cell lines to single amino acid starvation in 2-D monolayer versus 3-D spheroid culture. We revealed for the first time that in comparison with monolayer culture tumor cells, spheroids are much less susceptible to the deprivation of individual amino acids (i.e., arginine, leucine, lysine or methionine). Accordingly, even after prolonged (up to 10 days) starvation, spheroid cells could readily resume proliferation when appropriate amino acid was resupplemented. In the case of arginine deprivation, similar apoptosis induction was detected both in 2-D and 3-D culture, suggesting that this process does not determine the level of tumor cell sensitivity to this kind of treatment. It was also observed that spheroids much better mimic the in vivo ability of tumor cells to utilize citrulline as arginine precursor for growth in amino acid deficient environment. We conclude that 3-D spheroid culture better reflects in vivo tumor cell response to single amino acid starvation than 2-D monolayer culture and should be used as an integral model in the studies of this type of antitumor metabolic targeting. PMID:24036986

Vynnytska-Myronovska, Bozhena; Kurlishchuk, Yuliya; Bobak, Yaroslav; Dittfeld, Claudia; Kunz-Schughart, Leoni A; Stasyk, Oleh

2013-09-14

369

[Studies on interaction of acid-treated nanotube titanic acid and amino acids].  

PubMed

Nanotube titanic acid (NTA) has distinct optical and electrical character, and has photocatalysis character. In accordance with these qualities, NTA was treated with acid so as to enhance its surface activity. Surface structures and surface groups of acid-treated NTA were characterized and analyzed by Transmission Electron Microscope (TEM) and Fourier Transform Infrared Spectrometry (FT-IR). The interaction between acid-treated NTA and amino acids was investigated. Analysis results showed that the lengths of acid-treated NTA became obviously shorter. The diameters of nanotube bundles did not change obviously with acid-treating. Meanwhile, the surface of acid-treated NTA was cross-linked with carboxyl or esterfunction. In addition, acid-treated NTA can catch amino acid residues easily, and then form close combination. PMID:20649031

Zhang, Huqin; Chen, Xuemei; Jin, Zhensheng; Liao, Guangxi; Wu, Xiaoming; Du, Jianqiang; Cao, Xiang

2010-06-01

370

Extraterrestrial Amino Acids in the Almahata Sitta Meteorite  

NASA Astrophysics Data System (ADS)

The recovery of meteorite fragments from the 2008 TC3 asteroid impact, collectively named Almahata Sitta, revealed a rare, anomalous polymict ureilite containing large carbonaceous grains (Jenniskens et al. 2009). Here we report the first amino acid analysis of a meteorite from an F-type asteroid as part of the Almahata Sitta meteorite sample analysis consortium. A single fragment (piece #4, 1.2 grams) was crushed to a powder, and separate 0.1 g aliquots of the same meteorite were carried through identical hot-water extraction, acid hydrolysis and desalting procedures at NASA Goddard Space Flight Center and the Scripps Institution of Oceanography. The o-phthaldialdehyde/N-acetyl-L-cysteine amino acid derivatives in the extracts were analyzed by high performance liquid chromatography with UV fluorescence detection and time-of-flight mass spectrometry. Analyses of the meteorite extracts revealed a complex distribution of two- to six-carbon aliphatic amino acids with abundances ranging from 0.5 to 69 parts-per-billion (ppb). Glycine was the most abundant amino acid detected, however, since this protein amino acid is a common terrestrial contaminant, we are currently unable to rule out at least a partial terrestrial source. However, the D/L ratio of alanine in the meteorite was racemic, suggesting that very little terrestrial amino acid contamination. Several non-protein amino acids that are rare in the biosphere were also identified in the meteorite above background levels including D,L-4-amino-2-methybutyric acid (65 ± 8 ppb), D-isovaline (1.3 ± 0.1 ppb), L-isovaline (1.4 ± 0.1 ppb), and ?-aminoisobutryic acid (7.1 ± 5.8 ppb). The abundance of isovaline and AIB are 1000 times lower than the abundances found in the CM2 meteorite Murchison while D,L-4-amino-2-methybutyric acid is similar. The very low amino acid abundances and the presence of several amino acid decomposition products including methylamine, ethylamine, and isopropylamine are consistent with extensive thermal alteration of organic compounds on the parent asteroid.

Callahan, Michael; Aubrey, A.; Bada, J. L.; Dworkin, J. P.; Elsila, J. E.; Glavin, D. P.; Parker, E.; Jenniskens, P.

2009-09-01

371

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

372

Noncanonical amino acids in the interrogation of cellular protein synthesis.  

PubMed

Proteins in living cells can be made receptive to bioorthogonal chemistries through metabolic labeling with appropriately designed noncanonical amino acids (ncAAs). In the simplest approach to metabolic labeling, an amino acid analog replaces one of the natural amino acids specified by the protein's gene (or genes) of interest. Through manipulation of experimental conditions, the extent of the replacement can be adjusted. This approach, often termed residue-specific incorporation, allows the ncAA to be incorporated in controlled proportions into positions normally occupied by the natural amino acid residue. For a protein to be labeled in this way with an ncAA, it must fulfill just two requirements: (i) the corresponding natural amino acid must be encoded within the sequence of the protein at the genetic level, and (ii) the protein must be expressed while the ncAA is in the cell. Because this approach permits labeling of proteins throughout the cell, it has enabled us to develop strategies to track cellular protein synthesis by tagging proteins with reactive ncAAs. In procedures similar to isotopic labeling, translationally active ncAAs are incorporated into proteins during a "pulse" in which newly synthesized proteins are tagged. The set of tagged proteins can be distinguished from those made before the pulse by bioorthogonally ligating the ncAA side chain to probes that permit detection, isolation, and visualization of the labeled proteins. Noncanonical amino acids with side chains containing azide, alkyne, or alkene groups have been especially useful in experiments of this kind. They have been incorporated into proteins in the form of methionine analogs that are substrates for the natural translational machinery. The selectivity of the method can be enhanced through the use of mutant aminoacyl tRNA synthetases (aaRSs) that permit incorporation of ncAAs not used by the endogenous biomachinery. Through expression of mutant aaRSs, proteins can be tagged with other useful ncAAs, including analogs that contain ketones or aryl halides. High-throughput screening strategies can identify aaRS variants that activate a wide range of ncAAs. Controlled expression of mutant synthetases has been combined with ncAA tagging to permit cell-selective metabolic labeling of proteins. Expression of a mutant synthetase in a portion of cells within a complex cellular mixture restricts labeling to that subset of cells. Proteins synthesized in cells not expressing the synthetase are neither labeled nor detected. In multicellular environments, this approach permits the identification of the cellular origins of labeled proteins. In this Account, we summarize the tools and strategies that have been developed for interrogating cellular protein synthesis through residue-specific tagging with ncAAs. We describe the chemical and genetic components of ncAA-tagging strategies and discuss how these methods are being used in chemical biology. PMID:21815659

Ngo, John T; Tirrell, David A

2011-08-04

373

Evolutionary Systems Biology of Amino Acid Biosynthetic Cost in Yeast  

Microsoft Academic Search

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

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

2010-01-01

374

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

375

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

Code of Federal Regulations, 2010 CFR

...2009-07-01 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...

2009-07-01

376

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

377

Amino Acid Composition of Proteins: Selection against the Genetic Code  

Microsoft Academic Search

Distribution of amino acids in 68 representative proteins is compared with their distribution among 61 codons of the genetic code. Average amounts of lysine, aspartic acid, glutamic acid, and alanine are above the levels anticipated from the genetic code, and arginine, serine, leucine, cysteine, proline, and histidine are below such levels. Arginine plus lysine account for 11.0 percent of codons

Thomas H. Jukes; Richard Holmquist; Herbert Moise

1975-01-01

378

The Dissimilation of Amino Acids by Rhodospirillum rubrum  

Microsoft Academic Search

SUMMARY: Washed suspensions of a strain of Rhodospirillum rubrum S1 grown anaerobically in the light and incubated in the light under argon metabolized many of the 15 amino acids tested and produced ammonia and carbon dioxide as the prin- cipal extracellular products. Hydrogen was also produced in the presence of glutamic acid. Of the glutamic acid metabolized 80 yo of

G. S. Coleman

1956-01-01

379

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

PubMed

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

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

2010-04-04

380

Amino Acids in the Antarctic Martian Meteorite MIL03346  

NASA Astrophysics Data System (ADS)

Investigations of the Antarctic martian meteorite MIL03346 using high performance liquid chromatography and liquid chromatography time of flight mass spectrometry revealed that trace levels of amino acids are present.

Glavin, D. P.; Aubrey, A.; Dworkin, J. P.; Botta, O.; Bada, J. L.

2005-03-01

381

Placental Amino Acids Transport in Intrauterine Growth Restriction  

PubMed Central

The placenta represents a key organ for fetal growth as it acts as an interface between mother and fetus, regulating the fetal-maternal exchange of nutrients, gases, and waste products. During pregnancy, amino acids represent one of the major nutrients for fetal life, and both maternal and fetal concentrations are significantly different in pregnancies with intrauterine growth restriction when compared to uncomplicated pregnancies. The transport of amino acids across the placenta is a complex process that includes the influx of neutral, anionic, and cationic amino acids across the microvilluos plasma membrane of the syncytiotrophoblast, the passage through the cytoplasm of the trophoblasts, and the transfer outside the trophoblasts across the basal membrane into the fetal circulation. In this paper, we review the transport mechanisms of amino acids across the placenta in normal pregnancies and in pregnancies complicated by intrauterine growth restriction.

Avagliano, Laura; Garo, Chiara; Marconi, Anna Maria

2012-01-01

382

Placental amino acids transport in intrauterine growth restriction.  

PubMed

The placenta represents a key organ for fetal growth as it acts as an interface between mother and fetus, regulating the fetal-maternal exchange of nutrients, gases, and waste products. During pregnancy, amino acids represent one of the major nutrients for fetal life, and both maternal and fetal concentrations are significantly different in pregnancies with intrauterine growth restriction when compared to uncomplicated pregnancies. The transport of amino acids across the placenta is a complex process that includes the influx of neutral, anionic, and cationic amino acids across the microvilluos plasma membrane of the syncytiotrophoblast, the passage through the cytoplasm of the trophoblasts, and the transfer outside the trophoblasts across the basal membrane into the fetal circulation. In this paper, we review the transport mechanisms of amino acids across the placenta in normal pregnancies and in pregnancies complicated by intrauterine growth restriction. PMID:22997583

Avagliano, Laura; Garò, Chiara; Marconi, Anna Maria

2012-07-11

383

Mechanisms of amino acid polycondensation on silica and alumina surfaces  

NASA Astrophysics Data System (ADS)

Chemisorption products of bifunctional amino acid vapours on the surface of silica and alumina have been studied by the method of infrared spectroscopy. On the basis of the analysis of spectral data it is supposed that heterogeneous polycondensation of amino acids with formation of peptides proceeds under these conditions. The supposition was confirmed by the study of products of interaction of amino acid vapours with silica and alumina by the method of fast atom bombardment mass-spectrometry. It is established that in contrast to alumina the condensation of amino acids into linear peptides on silica surface proceeds only at presence of at least small amounts of water. The most probable mechanisms of extending of peptide chains are proposed on the basis of obtained experimental data.

Basiuk, Vladimir A.; Gromovoy, Taras Yu.; Golovaty, Vitaliy G.; Glukhoy, Alexandr M.

1990-11-01

384

Beta-amino acids and methods intermediates for making same  

US Patent & Trademark Office Database

Disclosed are .beta.-amino acids that are unsubstituted in the .beta. position; that are substituted in the .beta. position with an aryl group; that are substituted in the .alpha. position with an aryl group; that bear two substituents in the .alpha. position; and/or that are substituted in the .alpha. and .beta. positions with groups which, together with the carbon atoms at the .alpha. and .beta. positions, form a ring. Also disclosed are methods for making the above-mentioned .beta.-amino acids and other .beta.-amino acids which involve providing an .alpha.,.beta.-unsaturated imide; converting the .alpha.,.beta.-unsaturated imide to a 2-substituted-isoxazolidin-5-one; and converting the 2-substituted-isoxazolidin-5-one to a .beta.-amino acid.

2011-10-11

385

Comparing amino acid abundances and distributions across carbonaceous chondrite groups  

NASA Astrophysics Data System (ADS)

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; Dworkin, Jason; Callahan, Michael; Glavin, Daniel; Elsila, Jamie

2012-07-01

386

The Amino Acid Content of Sea Nettle ('Chrysaora quinquecirrha') Nematocysts.  

National Technical Information Service (NTIS)

A study of nematocyst preparations from the jellyfish, Chrysaora quinquecirrha, reveals the presence of hydroxyproline, glycine and other amino acids in concentrations generally compatible with those found in the collagen of invertebrates.

J. H. Stone J. W. Burnett R. Goldner

1969-01-01

387

Specific Reversible Concentration of Amino Acids in E. Coli.  

National Technical Information Service (NTIS)

There exists in Escherichia coli a series of specific systems responsible for a reversible concentration of exogenous amino acids, which precedes their incorporation into proteins. The properties of these systems explain a number of growth inhibitions and...

G. N. Cohen H. V. Rickenberg

1968-01-01

388

Improved separation of amino acids by thin-layer chromatography  

Microsoft Academic Search

Summary  The separation of 35 amino acids on Avicel F layers was investigated and 6 solvent systems are recommended for use either singly or in combination in 2-dimensional chromatography. The mechanisms and limitations of these methods are discussed.

T. Dale; W. E. Court

1981-01-01

389

Amino Acid Composition of Crystalline Botulinum Toxin, Type a.  

National Technical Information Service (NTIS)

The amino acid composition of the crystalline material was investigated using chromatographic techniques. The results of this analysis are presented, and some of the implications they have upon the subunit structure of the toxin are discussed.

D. Stefanye E. J. Schantz L. Spero

1967-01-01

390

Earth Microorganisms can Utilize D- and L-Amino Acids  

NASA Astrophysics Data System (ADS)

Enantiomerically-selective amino acid consumption underpins the Mars Oxidant experiment and the claim that Atacama soils are Mars-like. This idea is problematic: D-, as well as L- enantionmers, are utilized by earth organisms.

Zhang, G.; Sun, H. J.

2010-04-01

391

Modification of the Controls of the Beckman Amino Acid Analyzer.  

National Technical Information Service (NTIS)

Two simple modifications to the Beckman 120C amino acid analyzer were of considerable value in this laboratory. The first of these allowed the analyzer to make both buffer changes automatically during analyses of physiological fluids. The second mdoficati...

D. W. Thayer T. J. Connor

1969-01-01

392

Pyrolysis Gas Chromatography of Amino Acids and Proteins.  

National Technical Information Service (NTIS)

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

K. Anomata Y. Mashiko

1972-01-01

393

AAindex: amino acid index database, progress report 2008  

PubMed Central

AAindex is a database of numerical indices representing various physicochemical and biochemical properties of amino acids and pairs of amino acids. We have added a collection of protein contact potentials to the AAindex as a new section. Accordingly AAindex consists of three sections now: AAindex1 for the amino acid index of 20 numerical values, AAindex2 for the amino acid substitution matrix and AAindex3 for the statistical protein contact potentials. All data are derived from published literature. The database can be accessed through the DBGET/LinkDB system at GenomeNet (http://www.genome.jp/dbget-bin/www_bfind?aaindex) or downloaded by anonymous FTP (ftp://ftp.genome.jp/pub/db/community/aaindex/).

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

2008-01-01

394

Accelerated Operation of a Three-Sample Amino Acid Analyzer.  

National Technical Information Service (NTIS)

An operational procedure of a 3-sample amino acid analyzer is described which facilitates the simultaneous analysis of three samples in slightly more than six hours. The procedure features the washing and regeneration of the ion exchange columns with lith...

J. B. Garcia J. P. Ellis

1973-01-01

395

The potential of dairy lactic acid bacteria to metabolise amino acids via non-transaminating reactions and endogenous transamination  

Microsoft Academic Search

The metabolism of amino acids by 22 starter and 49 non-starter lactic acid bacteria (LAB) was studied in a system consisting of amino acids and non-growing cells without added amino acceptors such as ?-ketoglutarate. There were significant inter- and intra-species differences in the metabolism of amino acids. Some amino acids such as alanine, arginine, aspartate, serine and branched-chain amino acids

S.-Q. Liu; R. Holland; V. L. Crow

2003-01-01

396

l-Amino acid oxidase from Naja naja oxiana venom  

Microsoft Academic Search

A new l-amino acid oxidase (LAAO) was isolated from the Central Asian cobra Naja naja oxiana venom by size exclusion, ion exchange and hydrophobic chromatography. The N-terminal sequence and the internal peptide sequences share high similarity with other snake venom l-amino acid oxidases, especially with those isolated from elapid venoms. The enzyme is stable at low temperatures (?20 °C, ?70 °C) and

Mari Samel; Külli Tõnismägi; Gunilla Rönnholm; Heiki Vija; Jüri Siigur; Nisse Kalkkinen; Ene Siigur

2008-01-01

397

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

398

Transient optical absorption spectra in pulse irradiated solid amino acids  

Microsoft Academic Search

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

Z. P. Zagórski; Z. Tomasi?ski

1990-01-01

399

When quinones meet amino acids: chemical, physical and biological consequences  

Microsoft Academic Search

Summary.  Quinones and amino acids are usually compartmentally separated in living systems, however there are several junctions in which\\u000a they meet, react and influence. It occurs mainly in wounded, cut or crushed plant material during harvest, ensiling or disintegrating\\u000a cells. Diffusing polyphenols are oxidized by polyphenol oxidases (PPOs) to quinonic compounds, which associate reversibly\\u000a or irreversibly with amino acids and proteins.

S. Bittner

2006-01-01

400

Preoperative infusion of amino acids prevents postoperative hypothermia  

Microsoft Academic Search

Intraoperative infusion of amino acids has been found to stimulate energy expenditure and thereby prevent anaesthesia-induced hypothermia. Rectal temperature and respiratory gas exchange were measured in 24 female patients before and after isoflurane anaesthesia. Sixteen patients had an amino acid mixture of 240 kJ h 1 , infused over 1-2 h before anaesthesia and eight control patients received saline. We

E. SELLDÉN; R. BRÄNSTRÖM; T. BRUNDIN

401

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

Microsoft Academic Search

Until very recently, prebiotic amino acids were believed to have been generated in the atmosphere of the early Earth, as successfully simulated by the Urey-Miller experiments. Two independent studies now identified ice photochemistry in the interstellar medium as a possible source of prebiotic amino acids. Ultraviolet irradiation of ice mixtures containing identified interstellar molecules (such as H2O, CO2, CO, CH3OH,

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

2002-01-01

402

Enantiomeric resolution of amino acids by thin-layer chromatography  

Microsoft Academic Search

A simple and rapid method of separating optical isomers of amino acids on a reversed-phase TLC plate, without using impregnated plates or a chiral mobile phase, is described. Amino acids derivatized with 1-fluoro-2,4-dinitrophenyl-5-l-alanine amide were spotted on a reversed phase pre-coated TLC plate. Enantiomers of glutamate and aspartate were separated most effectively with solvent consisting of 25% acetonitrile in triethylamine-phosphate

Yoko Nagata; Teruhito Iida; Masaki Sakai

2001-01-01

403

Electrophysiological analysis of rat renal sugar and amino acid transport  

Microsoft Academic Search

We have used electrophysiological techniques in rat kidney proximal tubule to study the transport of the followingl-a-amino acids: alanine, phenylalanine, glutamine, methionine, cysteine, cystine, proline, and hydroxyproline as well as the transport of glycine and ß-alanine. When applied in millimolar concentrations in the tubular lumen in the presence of Na+, all amino acids tested were found to depolarize the tubular

I. Samaržija; E. Frömter

1982-01-01

404

Amino Acid Transport Systems in Biotechnologically Relevant Bacteria  

Microsoft Academic Search

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

Kay Marin; Reinhard Krämer

405

The Complete Amino Acid Sequence of Human Serum Transferrin  

Microsoft Academic Search

The complete amino acid sequence of human serum transferrin has been determined by aligning the structures of the 10 CNBr fragments. The order of these fragments in the polypeptide chain is deduced from the structures of peptides overlapping methionine residues and other evidence. Human transferrin contains 678 amino acid residues and--including the two asparagine-linked glycans--has an overall molecular weight of

Ross T. A. MacGillivray; Enrique Mendez; Sudhir K. Sinha; Michael R. Sutton; Janet Lineback-Zins; Keith Brew

1982-01-01

406

Amino acid nutrition: a two-step absorptive process.  

PubMed

A linkage between intestinal and tissue absorption of amino acids was perceived by Donald D. Van Slyke and Gustave M. Meyer in 1913, but soon overlooked by later authors. Today, on the 110th anniversary of Van Slyke's birth and the 80th anniversary of publication of their now-classic paper in the Journal of Biological Chemistry, the observation gains in nutritional significance and tells us, incidentally, why we should not dose ourselves with an isolated amino acid. PMID:8515893

Christensen, H N

1993-04-01

407

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

408

Extraterrestrial amino acids in the Almahata Sitta meteorite  

Microsoft Academic Search

Amino acid analysis of a meteorite fragment of asteroid 2008 TC3 called Almahata Sitta was carried out using reverse-phase liquid chromatography coupled with UV fluorescence detection and time-of-flight mass spectrometry (LC-FD\\/ToF-MS) as part of a sample analysis consortium. LC-FD\\/ToF-MS analyses of hot-water extracts from the meteorite revealed a complex distribution of two- to seven-carbon aliphatic amino acids and one- to

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

2010-01-01

409

Simplified protein design biased for prebiotic amino acids yields a foldable, halophilic protein  

PubMed Central

A compendium of different types of abiotic chemical syntheses identifies a consensus set of 10 “prebiotic” ?-amino acids. Before the emergence of biosynthetic pathways, this set is the most plausible resource for protein formation (i.e., proteogenesis) within the overall process of abiogenesis. An essential unsolved question regarding this prebiotic set is whether it defines a “foldable set”—that is, does it contain sufficient chemical information to permit cooperatively folding polypeptides? If so, what (if any) characteristic properties might such polypeptides exhibit? To investigate these questions, two “primitive” versions of an extant protein fold (the ?-trefoil) were produced by top-down symmetric deconstruction, resulting in a reduced alphabet size of 12 or 13 amino acids and a percentage of prebiotic amino acids approaching 80%. These proteins show a substantial acidification of pI and require high salt concentrations for cooperative folding. The results suggest that the prebiotic amino acids do comprise a foldable set within the halophile environment.

Longo, Liam M.; Lee, Jihun; Blaber, Michael

2013-01-01

410

Database of amino acid-nucleotide contacts in contacts in DNA-homeodomain protein  

NASA Astrophysics Data System (ADS)

The analysis of amino acid-nucleotide contacts in interfaces of the protein-DNA complexes, intended to find consistencies in the protein-DNA recognition, is a complex problem that requires an analysis of the physicochemical characteristics of these contacts and the positions of the participating amino acids and nucleotides in the chains of the protein and the DNA, respectively, as well as conservatism of these contacts. Thus, those heterogeneous data should be systematized. For this purpose we have developed a database of amino acid-nucleotide contacts ANTPC (Amino acid Nucleotide Type Position Conservation) following the archetypal example of the proteins in the homeodomain family. We show that it can be used to compare and classify the interfaces of the protein-DNA complexes.

Grokhlina, T. I.; Zrelov, P. V.; Ivanov, V. V.; Polozov, R. V.; Chirgadze, Yu. N.; Sivozhelezov, V. S.

2013-09-01

411

Regulation of renal amino acid transporters during metabolic acidosis.  

PubMed

The kidney plays a major role in acid-base homeostasis by adapting the excretion of acid equivalents to dietary intake and metabolism. Urinary acid excretion is mediated by the secretion of protons and titratable acids, particularly ammonia. NH(3) is synthesized in proximal tubule cells from glutamine taken up via specific amino acid transporters. We tested whether kidney amino acid transporters are regulated in mice in which metabolic acidosis was induced with NH(4)Cl. Blood gas and urine analysis confirmed metabolic acidosis. Real-time RT-PCR was performed to quantify the mRNAs of 16 amino acid transporters. The mRNA of phosphoenolpyruvate carboxykinase (PEPCK) was quantified as positive control for the regulation and that of GAPDH, as internal standard. In acidosis, the mRNA of kidney system N amino acid transporter SNAT3 (SLC38A3/SN1) showed a strong induction similar to that of PEPCK, whereas all other tested mRNAs encoding glutamine or glutamate transporters were unchanged or reduced in abundance. At the protein level, Western blotting and immunohistochemistry demonstrated an increased abundance of SNAT3 and reduced expression of the basolateral cationic amino acid/neutral amino acid exchanger subunit y(+)-LAT1 (SLC7A7). SNAT3 was localized to the basolateral membrane of the late proximal tubule S3 segment in control animals, whereas its expression was extended to the earlier S2 segment of the proximal tubule during acidosis. Our results suggest that the selective regulation of SNAT3 and y(+)LAT1 expression may serve a major role in the renal adaptation to acid secretion and thus for systemic acid-base balance. PMID:17003226

Moret, Caroline; Dave, Mital H; Schulz, Nicole; Jiang, Jean X; Verrey, Francois; Wagner, Carsten A

2006-09-26

412

Carbohydrate and amino acid composition of dissolved organic matter leached from soil  

Microsoft Academic Search

Low molecular weight organic substances (LMWOS) in soil and soil solution include mainly amino acids, carboxylic acids, and carbohydrates. Due to their high bioavailability they play a crucial role in the cycles of C and nutrients in soils. The variety of soil processes that involve LMWOS requires identifying their composition to elucidate reactions and transformations. In most studies, LMWOS are

Holger Fischer; Axel Meyer; Klaus Fischer; Yakov Kuzyakov

2007-01-01

413

FTO expression is regulated by availability of essential amino acids.  

PubMed

Genome-wide association studies have revealed that single nucleotide polymorphisms in fat mass and obesity-associated transcript (FTO) are robustly associated with body mass index and obesity. Expression of Fto in the hypothalamic arcuate nucleus is bidirectionally regulated as a function of nutritional status; decreasing following a 48-h fast and increasing after 10-week exposure to a high-fat diet. Here, we utilize an in vitro approach to determine which nutrients could regulate FTO levels at a cellular level. Using mouse and human cell lines, we find that FTO levels are not influenced by serum starvation. We demonstrate, however, that both glucose and total amino-acid deprivation regulates FTO expression. In particular, we have found that FTO mRNA and protein levels are dramatically downregulated by total amino-acid deprivation in mouse hypothalamic N46 cells, mouse embryonic fibroblasts and in human HEK293 cells. The drop rate of Fto mRNA is faster than its rate of natural degradation, pointing to regulation at the transcriptional level, which is reversible upon amino-acid replacement. Strikingly, this downregulation was seen only with essential amino-acid deficiency and not nonessential amino acids. These data suggest that FTO might have a role in the sensing of essential amino-acid availability. PMID:22614055

Cheung, M K; Gulati, P; O'Rahilly, S; Yeo, G S H

2012-05-22

414

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

2012-09-21

415

Role of ferrocyanides in the prebiotic synthesis of ?-amino acids.  

PubMed

We investigated the synthesis of ?-amino acids under possible prebiotic terrestrial conditions in the presence of dissolved iron (II) in a simulated prebiotic ocean. An aerosol-liquid cycle with a prebiotic atmosphere is shown to produce amino acids via Strecker synthesis with relatively high yields. However, in the presence of iron, the HCN was captured in the form of a ferrocyanide, partially inhibiting the formation of amino acids. We showed how HCN captured as Prussian Blue (or another complex compound) may, in turn, have served as the HCN source when exposed to UV radiation, allowing for the sustained production of amino acids in conjunction with the production of oxyhydroxides that precipitate as by-products. We conclude that ferrocyanides and related compounds may have played a significant role as intermediate products in the prebiotic formation of amino acids and oxyhydroxides, such as those that are found in iron-containing soils and that the aerosol cycle of the primitive ocean may have enhanced the yield of the amino acid production. PMID:23780697

Ruiz-Bermejo, Marta; Osuna-Esteban, Susana; Zorzano, María-Paz

2013-06-19

416

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

417

On the utility of alternative amino acid scripts  

PubMed Central

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

Flower, Darren R

2012-01-01

418

New amino acid indices based on residue network topology.  

PubMed

Amino acid indices are useful tools in bioinformatics. With the appearance of novel theory and technology, and the rapid increase of experimental data, building new indices to cope with new or unsolved old problems is still necessary. In this study, residue networks are constructed from the PDB structures of 640 representative proteins based on the distance between Calpha atoms with an 8 A cutoff. All these networks show typical small world features. New amino acid indices, termed relative connectivity, clustering coefficient, closeness and betweenness, are derived from the corresponding topological parameters of amino acids in the residue networks. The 4 new network based indices are closely clustered together and related to hydrophobicity and beta propensity. When compared with related amino acid indices, the new indices show better or comparable performance in protein surface residue prediction. Relative connectivity is the best index and can reach a useful performance with an area under the curve about 0.75. It indicates that the network property based amino acid indices can be useful complements to the existing physicochemical property based amino acid indices. PMID:18546483

Huang, Jian; Kawashima, Shuichi; Kanehisa, Minoru

2007-01-01

419

Amino acid metabolism and regulatory effects in aging  

PubMed Central

Purpose of review To examine recent discoveries related to the amino acid metabolism and regulatory effects in aging, focusing on the development and treatment of age-related muscle loss (sarcopenia). Recent findings While basal amino acid metabolism may be unaffected by age, elderly subjects appear to have a decreased ability to respond to anabolic stimuli such as insulin and, to a lesser extent, amino acids. Specifically, compared to young subjects, the stimulation of muscle protein synthesis is attenuated in elderly subjects following the administration of mixed meals due to insulin resistance. In addition, the anabolic effect of amino acids appears blunted at low doses. Recent studies, however, have highlighted that these age-related alterations in amino acid metabolism may be overcome by provision of excess leucine, changes in the daily protein intake pattern or exercise, which improve activation of translation initiation and muscle protein synthesis. Summary Muscle loss with aging is associated with significant changes in amino acid metabolism, which can be acutely reversed using nutritional manipulations and exercise. Long-term, large clinical trials are, however, needed to determine the clinical significance of these findings in the elderly population, and to establish if nutritional and exercise interventions can help prevent and treat sarcopenia.

Timmerman, Kyle L.; Volpi, Elena

2009-01-01

420

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

PubMed

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

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

2010-03-01

421

Amino acid profiles of lactic acid bacteria, isolated from kefir grains and kefir starter made from them.  

PubMed

The characteristics of cell growth, lactic acid production, amino acid release and consumption by single-strain cultures of lactic acid bacteria (isolated from kefir grains), and by a multiple-strain kefir starter prepared from them, were studied. The change in the levels of free amino acids was followed throughout the kefir process: single-strain kefir bacteria and the kefir starter (Lactococcus lactis C15-1%+Lactobacillus helveticus MP12-3%+(Streptococcus thermophilus T15+Lactobacillus bulgaricus HP1 = 1:1)-3%) were cultivated in pasteurized (92 degrees C for 20 min) cow's milk (3% fat content) at 28 degrees C for 5 h (the kefir starter reached pH 4.7) and subsequently grown at 20 degrees C for 16 h; storage was at 4 degrees C for 168 h. The strain L. helveticus MP12 was unrivaled with respect to free amino acid production (53.38 mg (100 g)(-1)) and cell growth (17.8 x 10(8) CFU ml(-1)); however, it manifested the lowest acidification activity. L. bulgaricus HP1 released approximately 3.7 times less amino acids, nearly 5 times lower cell growth, and produced about 1.2 times more lactic acid. S. thermophilus T15 demonstrated dramatically complex amino acid necessities for growth and metabolism. With L. lactis C15, the highest levels of growth and lactic acid synthesis were recorded (18.3 x 10(8) CFU ml(-1) and 7.8 g l(-1) lactic acid at the 21st hour), and as for free amino acid production, it approximated L. bulgaricus HP1 (17.03 mg (100 g)(-1) maximum concentration). In the L. lactis C15 culture, the amino acids were used more actively throughout the first exponential growth phase (by the 10th hour) than during the second growth phase. The unique properties of the L. helveticus MP12 strain to produce amino acids were employed to create a symbiotic bioconsortium kefir culture, which, under conditions of kefir formation, enhanced lactic acid production and shortened the time required to reach pH 4.7; intensified cell growth activity, resulting in a respective 90- and 60-fold increase in the concentration of lactobacilli and cocci in the mixed culture compared to individual cultures; and accumulated free amino acids in the final kefir with higher total concentrations (56.88 mg (100 g)(-1)) and an individual concentration of essential amino acids (1.5 times) greater than that of yogurt. PMID:16297479

Simova, Emilina; Simov, Zhelyasko; Beshkova, Dora; Frengova, Ginka; Dimitrov, Zhechko; Spasov, Zdravko

2005-11-16

422

Proton affinity of several basic non-standard amino acids  

NASA Astrophysics Data System (ADS)

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

Rožman, Marko

2012-08-01

423

Induction of the d-Amino Acid Oxidase from Trigonopsis variabilis  

PubMed Central

Induction of the d-amino acid oxidase (EC. 1.4.3.3) from the yeast Trigonopsis variabilis was investigated by using a minimal medium containing glucose as the carbon and energy source, (NH(inf4))(inf2)SO(inf4) as the nitrogen source, and various d- and dl-amino acid derivatives as inducers. The best new inducers found were N-carbamoyl-d-alanine, N-acetyl-d-tryptophan, and N-chloroacetyl-d-(alpha)-aminobutyric acid; when the induction effects of these compounds were compared with the effects of d-alanine as the nitrogen source and inducer, the resulting activities of d-amino acid oxidase per gram of dried yeast were 4.2, 2.1, and 1.5 times higher, respectively. The optimum concentration of the best inducer, N-carbamoyl-d-alanine, was 5 mM. This inducer could also be used in its racemic form. The induction was pH dependent. After cultivation of the yeast in a 50-liter bioreactor, d-amino acid oxidase activity of about 3,850 (mu)kat (231,000 U) was obtained. In addition, production of the d-amino acid oxidase was found to be significantly dependent on the metal salt composition of the medium. Addition of zinc ions was required to obtain high d-amino acid oxidase levels in the cells. The optimum concentration of ZnSO(inf4) was about 140 (mu)M.

Horner, R.; Wagner, F.; Fischer, L.

1996-01-01

424

Stereocontrolled synthesis of quaternary ?,?-unsaturated amino acids: chain extension of d- and l-?-(2-tributylstannyl)vinyl amino acids  

Microsoft Academic Search

A pair of diastereomeric (4S,5S)- and (4S,5R)-4-methoxycarbonyl-5-phenylselenomethyl-2-phenyl oxazolines, derived from l-vinylglycine, serve as precursors to protected, quaternary, l- and d-?-(2-tributylstannyl)vinyl amino acids, respectively, in three steps {(i) alkylative side chain installation, (ii) eliminative ring-opening and (iii) vinyl selenide to vinyl stannane interconversion}. The title compounds may be protodestannylated to the corresponding free, quaternary l- and d-vinyl amino acids. Alternatively, the

David B Berkowitz; Esmort Chisowa; Jill M McFadden

2001-01-01

425