scholarly journals Glutamine: precursor or nitrogen donor for citrulline synthesis?

2010 ◽  
Vol 299 (1) ◽  
pp. E69-E79 ◽  
Author(s):  
Juan C. Marini ◽  
Inka Cajo Didelija ◽  
Leticia Castillo ◽  
Brendan Lee
Keyword(s):  
Amino Acids ◽  
Current Literature ◽  
Ammonium Acetate ◽  
Carbon Skeleton ◽  
Amino Group ◽  
Amino Groups ◽  
Amido Group ◽  
Nitrogen Donor ◽  
Citrulline Synthesis

Although glutamine is considered the main precursor for citrulline synthesis, the current literature does not differentiate between the contribution of glutamine carbon skeleton vs. nonspecific nitrogen (i.e., ammonia) and carbon derived from glutamine oxidation. To elucidate the role of glutamine and nonspecific nitrogen in the synthesis of citrulline, l-[2-15N]- and l-[5-15N]glutamine and 15N-ammonium acetate were infused intragastrically in mice. The amino group of glutamine labeled the three nitrogen groups of citrulline almost equally. The amido group and ammonium acetate labeled the ureido and amino groups of citrulline, but not the δ-nitrogen. D5-glutamine also infused in this arm of the study, which traces the carbon skeleton of glutamine, was utilized poorly, accounting for only 0.2–0.4% of the circulating citrulline. Dietary glutamine nitrogen (both N groups) incorporation was 25-fold higher than the incorporation of its carbon skeleton into citrulline. To investigate the relative contributions of the carbon skeleton and nonspecific carbon of glutamine, arginine, and proline to citrulline synthesis, U-13Cn tracers of these amino acids were infused intragastrically. Dietary arginine was the main precursor for citrulline synthesis, accounting for ∼40% of the circulating citrulline. Proline contribution was minor (3.4%), and glutamine was negligible (0.4%). However, the glutamine tracer resulted in a higher enrichment in the ureido group, indicating incorporation of nonspecific carbon from glutamine oxidation into carbamylphosphate used for citrulline synthesis. In conclusion, dietary glutamine is a poor carbon skeleton precursor for the synthesis of citrulline, although it contributes both nonspecific nitrogen and carbon to citrulline synthesis.

scholarly journals The Role of Skeletal Muscle in The Pathogenesis of Altered Concentrations of Branched-Chain Amino Acids (Valine, Leucine, and Isoleucine) in Liver Cirrhosis, Diabetes, and Other Diseases

2021 ◽  
pp. 293-305
Author(s):  
M Holeček
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Liver Cirrhosis ◽  
Fatty Acid ◽  
Fatty Acid Oxidation ◽  
Branched Chain Amino Acids ◽  
Acid Oxidation ◽  
Amino Group ◽  
Branched Chain

The article shows that skeletal muscle plays a dominant role in the catabolism of branched-chain amino acids (BCAAs; valine, leucine, and isoleucine) and the pathogenesis of their decreased concentrations in liver cirrhosis, increased concentrations in diabetes, and nonspecific alterations in disorders with signs of systemic inflammatory response syndrome (SIRS), such as burn injury and sepsis. The main role of skeletal muscle in BCAA catabolism is due to its mass and high activity of BCAA aminotransferase, which is absent in the liver. Decreased BCAA levels in liver cirrhosis are due to increased use of the BCAA as a donor of amino group to α-ketoglutarate for synthesis of glutamate, which in muscles acts as a substrate for ammonia detoxification to glutamine. Increased BCAA levels in diabetes are due to alterations in glycolysis, citric acid cycle, and fatty acid oxidation. Decreased glycolysis and citric cycle activity impair BCAA transamination to branched-chain keto acids (BCKAs) due to decreased supply of amino group acceptors (α-ketoglutarate, pyruvate, and oxaloacetate); increased fatty acid oxidation inhibits flux of BCKA through BCKA dehydrogenase due to increased supply of NADH and acyl-CoAs. Alterations in BCAA levels in disorders with SIRS are inconsistent due to contradictory effects of SIRS on muscles. Specifically, increased proteolysis and insulin resistance tend to increase BCAA levels, whereas activation of BCKA dehydrogenase and glutamine synthesis tend to decrease BCAA levels. The studies are needed to elucidate the role of alterations in BCAA metabolism and the effects of BCAA supplementation on the outcomes of specific diseases.

scholarly journals o-Quinones formed in plant extracts. Their reactions with amino acids and peptides

1969 ◽  
Vol 112 (5) ◽  
pp. 609-616 ◽  
Author(s):  
W. S. Pierpoint
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Plant Extracts ◽  
Thiol Group ◽  
Amino Group ◽  
Amino Groups ◽  
Terminal Amino Acid ◽  
Secondary Reactions ◽  
Terminal Amino ◽  
Group 5

1. The reactions of amino acids and peptides with the o-quinones produced by the enzymic oxidation of chlorogenic acid and caffeic acid have been studied manometrically and spectrophotometrically. 2. Amino acids, except lysine and cysteine, react primarily through their α-amino groups to give red or brown products. These reactions, which compete with the polymerization of the quinones, are followed by secondary reactions that may absorb oxygen and give products with other colours. 3. The ∈-amino group of lysine reacts with the o-quinones in a similar way. The thiol group of cysteine reacts with the quinones, without absorbing oxygen, giving colourless products. 4. Peptides containing cysteine react with the o-quinones through their thiol group. 5. Other peptides, such as glycyl-leucine and leucylglycine, react primarily through their α-amino group and the overall reaction resembles that of the N-terminal amino acid except that it is quicker. 6. With some peptides, the secondary reactions differ from those that occur between the o-quinones and the N-terminal amino acids. The colours produced from carnosine resemble those produced from histidine rather than those from β-alanine, and the reactions of prolylalanine with o-quinones are more complex than those of proline.

Increased Resistance of Peptides to Serum Proteases by Modification of their Amino Groups

2003 ◽  
Vol 58 (7-8) ◽  
pp. 558-561 ◽  
Author(s):  
Rossella Galati ◽  
Alessandra Verdina ◽  
Giuliana Falasca ◽  
Alberto Chersi
Keyword(s):  
Amino Acids ◽  
Proteolytic Enzymes ◽  
Living Organism ◽  
Amino Group ◽  
Amino Groups ◽  
Protein Fragments ◽  
Beta Alanine ◽  
Synthetic Protein ◽  
In Vivo Tests

Abstract The ability of synthetic protein fragments to survive the degradative action of aminopeptidases and serum proteolytic enzymes can be remarkably enhanced by slight modifications at their N-terminal alpha-amino group. This can be achieved by addition of beta-alanine or amino acids of the d-configuration, amino acids which are seldom found in a living organism. These modifications do scarcely modify the chemical and physical properties of the peptides, and should be preferrred, especially for in vivo tests, to drastic alterations of peptides as produced by dinitrophenylation or dansylation of the amino groups.

scholarly journals The measurement of amino groups in proteins and peptides

1971 ◽  
Vol 124 (3) ◽  
pp. 581-590 ◽  
Author(s):  
R Fields
Keyword(s):  
Amino Acids ◽  
Room Temperature ◽  
Thiol Group ◽  
Amino Group ◽  
Thiol Groups ◽  
Amino Groups ◽  
Model Compounds ◽  
Time Required ◽  
Short Time ◽  
Proteins And Peptides

A technique is examined for determining amino groups with 2,4,6-trinitrobenzenesulphonic acid, in which the extinction at 420nm of sulphite complexes of the trinitrophenylated amino groups is measured. The sensitivity of the method is 5–200nmol of amino group. The method is especially suitable for checking the extent of blocking or unblocking of amino groups in proteins and peptides, owing to the short time required for reaction (5min at room temperature). The reaction of the reagent with thiol groups has been studied and was found to proceed 30–50 times faster than with ∈-amino groups of model compounds. The ∈420 of a trinitrophenylated thiol group was found to be 2250m-1·cm-1. The reaction with several amino acids, peptides and proteins is presented. The ∈420 of a typical α-amino group was found to be 22000m-1·cm-1 and that of an ∈-amino group, 19200m-1·cm-1. Difficulties inherent in the analysis of constituent amino group reactions in proteins are discussed.

The ability of the NiSOD binding loop to chelate zinc(ii): the role of the terminal amino group in the enzymatic functions

2019 ◽  
Vol 48 (18) ◽  
pp. 6217-6227 ◽  
Author(s):  
Gizella Csire ◽  
András Kolozsi ◽  
Tamás Gajda ◽  
Giuseppe Pappalardo ◽  
Katalin Várnagy ◽  
...  
Keyword(s):  
Crucial Role ◽  
Spectroscopic Characterization ◽  
Amino Group ◽  
Amino Groups ◽  
Enzymatic Function ◽  
Terminal Amino ◽  
Binding Loop

Equilibrium and spectroscopic characterization of zinc(ii) complexes with NiSOD related peptides highlights the crucial role of terminal amino groups in the enzymatic function.

scholarly journals The reaction of 2,4,6-trinitrobenzenesulphonic acid with amino acids, peptides and proteins

1968 ◽  
Vol 108 (3) ◽  
pp. 383-391 ◽  
Author(s):  
R. B. Freedman ◽  
G. K. Radda
Keyword(s):  
Amino Acids ◽  
Glutamate Dehydrogenase ◽  
Free Amino ◽  
Reactive Species ◽  
Second Order ◽  
Amino Group ◽  
Exponential Rate ◽  
Amino Groups ◽  
Sh Group ◽  
Kinetics Of

1. The kinetics of the reaction of 2,4,6-trinitrobenzenesulphonic acid with various amino acids, peptides and proteins were studied by spectrophotometry. 2. The reaction of the α- and ∈-amino groups in simple amino acids was found to be second-order, and the unprotonated amino group was shown to be the reactive species. 3. By allowing for the concentration of unreactive −NH3+ group, intrinsic reactivities for the free amino groups were derived and shown to be correlated with the basicities. 4. The SH group of N-acetylcysteine was found to be more reactive to 2,4,6-trinitrobenzenesulphonic acid than most amino groups. 5. The reactions of insulin, chymotrypsinogen and ribonuclease with 2,4,6-trinitrobenzenesulphonic acid were analysed in terms of three exponential rate curves, each referring to one or more amino groups of the proteins. 6. The reaction of lysozyme with 2,4,6-trinitrobenzenesulphonic acid was found to display an acceleration effect. 7. From the reaction of 2,4,6-trinitrobenzenesulphonic acid with glutamate dehydrogenase at several enzyme concentrations, it was possible to discern two sets of amino groups of different reactivity, and to show that the number of groups in each set was decreased by aggregation of the enzyme.

scholarly journals In Vitro Increase in Chloroquine Accumulation Induced by Dihydroethano- and Ethenoanthracene Derivatives in Plasmodium falciparum-Parasitized Erythrocytes

2002 ◽  
Vol 46 (7) ◽  
pp. 2061-2068 ◽  
Author(s):  
Bruno Pradines ◽  
Sandrine Alibert ◽  
Carole Houdoin ◽  
Christiane Santelli-Rouvier ◽  
Joel Mosnier ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Resistant Strain ◽  
Susceptible Strain ◽  
Amino Group ◽  
Resistant Clone ◽  
Amino Groups ◽  
Cellular Accumulation ◽  
Basic Group ◽  
Amido Group

ABSTRACT The effects of a series of dihydroethano- and ethenoanthracene derivatives on chloroquine (CQ) accumulation in CQ-susceptible strain 3D7 and CQ-resistant clone W2 were assessed. The levels of CQ accumulation increased little or none in CQ-susceptible strain 3D7 and generally increased markedly in CQ-resistant strain W2. At 10 μM, 28 compounds yielded cellular accumulation ratios (CARs) greater than that observed with CQ alone in W2. At 10 μM, in strain W2, 21 of 31 compounds had CQ CARs two or more times higher than that of CQ alone, 15 of 31 compounds had CQ CARs three or more times higher than that of CQ alone, 13 of 31 compounds had CQ CARs four or more times higher than that of CQ alone, and 9 of 31 compounds had CQ CARs five or more times higher than that of CQ alone. At 1 μM, 17 of 31 compounds had CQ CARs two or more times higher than that of CQ alone, 12 of 31 compounds had CQ CARs three or more times higher than that of CQ alone, 6 of 31 compounds had CQ CARs four or more times higher than that of CQ alone, and 3 of 31 compounds had CQ CARs five or more times higher than that of CQ alone. At 1 μM, 17 of 31 compounds were more potent inducers of CQ accumulation than verapamil and 12 of 31 compounds were more potent inducers of CQ accumulation than promethazine. The nature of the basic group seems to be associated with increases in the levels of CQ accumulation. At 1 and 10 μM, 10 of 14 and 13 of 14 compounds with amino group (amines and diamines), respectively, had CARs ≥3, while at 1 and 10 μM, only 1 of the 13 derivatives with amido groups had CARs ≥3. Among 12 of the 31 compounds which were more active inducers of CQ accumulation than promethazine at 1 μM, 10 had amino groups and 1 had an amido group.

Recognition of aminoglycoside antibiotics by enterococcal-staphylococcal aminoglycoside 3'-phosphotransferase type IIIa: role of substrate amino groups.

1996 ◽  
Vol 40 (11) ◽  
pp. 2648-2650 ◽  
Author(s):  
G A McKay ◽  
J Roestamadji ◽  
S Mobashery ◽  
G D Wright
Keyword(s):  
Steady State ◽  
Aminoglycoside Antibiotics ◽  
Hydroxyl Group ◽  
Amino Group ◽  
Amino Groups ◽  
Type Iiia ◽  
Steady State Kinetic ◽  
State Kinetic

The interactions of the aminoglycoside 3'-phosphotransferase IIIa with aminoglycoside antibiotics lacking specific amino groups were examined by steady-state kinetic analyses. The results demonstrate that an amino group on C-1 and either an amino or a hydroxyl group at the 2' and 6' positions are important for detoxification of aminoglycosides by this enzyme.

scholarly journals Mechanisms of heat damage in proteins

1970 ◽  
Vol 24 (1) ◽  
pp. 313-329 ◽  
Author(s):  
J. Bjarnason ◽  
K. J. Carpenter
Keyword(s):  
Amino Acids ◽  
Main Reaction ◽  
Amino Group ◽  
Amino Groups ◽  
Sulphur Compounds ◽  
Plasma Albumin ◽  
Small Loss ◽  
Bovine Plasma ◽  
Carboxylic Groups ◽  
Ammonia Liberation

1. Bovine plasma albumin (BPA) containing approximately 14% moisture, when heated for 27 h at 115° suffered an appreciable loss of cystine and a small loss of lysine; at 145° all the amino acids except glutamic acid and those with paraffin side-chains, showed considerable losses. Isoleucine also showed some loss through racemization to alloisoleucine.2. BPA heated at 115° evolved H2S; at 145° other sulphur compounds were released as well, all coming from the breakdown of cystine. Possible mechanisms for this are discussed.3. Ammonia was also liberated from BPA heated at 115°. The degree of correlation of lysine binding in different proteins with ammonia liberation and amide changes has led us to suggest that the main reaction of ε-amino lysine groups is with amide groups of asparagine and glutamine. Reaction of ε-amino groups with carboxylic groups is thought to be less important.4. Model experiments have shown that a reaction between amide groups and the e-amino group of lysine in proteins can occur at practical drying temperatures.5. Reactions of the ε-amino group of lysine with destruction products of cystine is also considered to be partially responsible for the lysine binding in heated proteins.

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