Effect of Amino Group Charge on the Photooxidation Kinetics of Aromatic Amino Acids

2013 ◽  
Vol 118 (2) ◽  
pp. 339-349 ◽  
Author(s):  
Natalya N. Saprygina ◽  
Olga B. Morozova ◽  
Günter Grampp ◽  
Alexandra V. Yurkovskaya
Keyword(s):  
Amino Acids ◽  
Aromatic Amino Acids ◽  
Amino Group ◽  
Kinetics Of

scholarly journals The reaction of ornithine aminotransferase with ornithine

1982 ◽  
Vol 201 (1) ◽  
pp. 221-225 ◽  
Author(s):  
J A Williams ◽  
G Bridge ◽  
L J Fowler ◽  
R A John
Keyword(s):  
Amino Acids ◽  
Carbon Atom ◽  
Rat Liver ◽  
Dissociation Constants ◽  
Amino Group ◽  
Ornithine Aminotransferase ◽  
Mammalian Enzyme ◽  
Kinetics Of ◽  
Plant Enzyme

Rat liver ornithine aminotransferase is found to exchange the pro-S hydrogen on the delta-carbon atom of ornithine exclusively, thus showing that the mammalian enzyme transfers the delta-amino group and not the alpha-amino group as has been demonstrated with the plant enzyme [Mestichelli, Gupta & Spenser (1979) J. Biol. Chem. 254, 640-647]. The enzyme also transfers the alpha-amino group of glutamate and the kinetics of the half reactions between the enzyme and both amino acids are compared. Rate and dissociation constants for both reactions are determined.

Studies on the absorption of amino acids by larval tapeworms (Cyclophyllidea: Taenia crassiceps)

Parasitology ◽  
1968 ◽  
Vol 58 (1) ◽  
pp. 47-59 ◽  
Author(s):  
W. D. G. Haynes ◽  
Angela E. R. Taylor
Keyword(s):  
Amino Acids ◽  
Glutamic Acid ◽  
Active Transport ◽  
Aromatic Amino Acids ◽  
Hymenolepis Diminuta ◽  
Amino Group ◽  
Absorption Mechanism ◽  
Taenia Crassiceps ◽  
Acidic Amino Acids ◽  
Research Grant

Larvae of Taenia crassiceps have been shown to absorb L-valine and L-methionine by a process of active transport. Uptake is maximal at about 43 °C and a pH of about neutrality, and concentration against a gradient has been demonstrated. In advanced larvae, the absorption mechanism has been shown to be specific for neutral aliphatic amino acids, with an uncharged amino group in the α-position. Competitive inhibitions of uptake have been demonstrated in the presence of other amino acids.Comparison has been made with a mechanism present in Hymenolepis diminuta for the uptake of neutral amino acids, demonstrated by Read et al. (1963), and the absorption of L-methionine by the two species has been compared in detail.The uptake of valine and methionine by the two types of larvae has been compared in detail: the presence of two types of sites for the uptake of these aminoacids has been suggested.The absorption of the L-isomers of glutamic acid, proline, serine, glycine and leucine has been demonstrated in advanced larvae. Separate mechanisms for the uptake of acidic amino acids, basic amino acids and neutral aromatic amino acids have been suggested.Thanks are due to Professor G. Chapman, in whose department this work was carried out, and to Miss E. Clarry for her willing assistance. We would also like to thank Dr G. Ayrey, of the Queen Elizabeth College Isotope Unit, for his valuable help, especially in the development of a technique for the simultaneous counting of 14C and 3H. The work was supported by a research grant from the Wellcome Trustees, to whom we are most grateful.

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.

The Reaction of Aminoacylase with Chloromethylketone Analogs of Amino Acids

1977 ◽  
Vol 32 (9-10) ◽  
pp. 769-776 ◽  
Author(s):  
Jürgen Frey ◽  
Werner Kordel ◽  
Friedhelm Schneider
Keyword(s):  
Amino Acids ◽  
Aspartic Acid ◽  
Active Site ◽  
Lysine Residue ◽  
Amino Group ◽  
Sh Groups ◽  
Competitive Inhibitors ◽  
Kinetics Of ◽  
Covalently Bound

Abstract1. Aminoacylase is irreversibly inactivated by the chloromethylketone analogs of benzyloxy-carbonyl-L-alanine, L-alanine, L-leucine, L-aspartic acid (β), tosyl-L-phenylalanine and L-leucyl-L-alanine. The kinetics of the inactivation of the enzyme by the halo-methylketones were investigated.2. Leucyl-and alanyl chloromethylketone inactivate the enzyme by blocking of 4 SH groups. Experiments with [U-14C] leucyl chloromethylketone confirm that maximal 4 residues are covalently bound to the protein.3. Inactivation of the enzyme by benzyloxycarbonylalanyl and tosylphenylalanyl chloromethyl­ ketone is the result of the substitution of the £-amino group of one lysine residue per active site and not of SH groups. However, in the presence of competitive inhibitors these halomethylketones react only with the SH groups of the enzyme, too.

Effect of aging on intestinal absorption of aromatic amino acids in vitro in the rat

1988 ◽  
Vol 254 (4) ◽  
pp. G630-G636 ◽  
Author(s):  
Farhad Navab ◽  
Charles G. Winter
Keyword(s):  
Amino Acids ◽  
Age Groups ◽  
Aromatic Amino Acids ◽  
Intestinal Length ◽  
Old Rats ◽  
Kinetics Of Uptake ◽  
Neurotransmitter Precursors ◽  
Kinetics Of ◽  
Two Age Groups

Whole-thickness everted jejunal rings were used to measure uptake of l-tyrosine (l-Tyr), l-phenylalanine (l-Phe), and l-tryptophan (l-Trp) in 6-, 12-, and 24-mo-old rats. The rate of uptake of all three amino acids (1 mM) was significantly reduced after 20 min of incubation in 24-mo-old compared with 6-mo-old rats. Results of influx (2 min) of 0.5-40.0 mM l-Phe and l-Trp suggested an increased affinity but decreased capacity for the transporter with age; these differences were significant for l-Trp (P < 0.05). Respective values for apparent Kt and Vmax were the following: l-Phe 6-mo-old rats, 5.46 mM and 1.03 μmol·g-1·2 min-1; 24-mo-old rats, 2.54 mM and 0.51 μmol·g-1·2 min-1; l-Trp 6-mo-old rats, 5.09 mM and 0.38 μmol·g-1·2 min-1; 24-mo-old rats, 3.20 mM and 0.25 μmol·g-1·2 min-1. Values for 12-mo-old rats fell in between the other two age groups. intestinal weight; intestinal length; Fischer rats; kinetics of uptake; Hofstee plot; everted jejunal rings; neurotransmitter precursors Submitted on June 14,1986 Accepted on November 9,1987

The kinetics of combination of carbon dioxide with the anions of glycine, glycyl-glycine, and related amino acids

1966 ◽  
Vol 164 (996) ◽  
pp. 401-410 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Amino Acids ◽  
Acetic Acid ◽  
Caproic Acid ◽  
Thermal Method ◽  
Amino Group ◽  
Phenyl Acetic Acid ◽  
Kinetics Of ◽  
Phenyl Alanine ◽  
Glycyl Glycine

The velocity constants k ' of the reaction of carbon dioxide with the anions of the amino acids glycine, glycyl-glycine, α-alanine, β-alanine, valine, histidine, β-phenyl alanine, α-amino phenyl acetic acid, and e-amino caproic acid have been determined by the rapid thermal method. At 25 °C the value of k ' is given approximately by the equation log 10 k ' = 0.262 p K + 1.197 where p K is the p K value of the amino group which reacts. For glycine and glycyl-glycine the energies of activation have been determined as 8.2 and 8.3 kcal respectively over the range 10 to 40 °C.

The Kinetics of Inhibition of the Action of Thrombin by the Fibrinopeptides Formed during the Clotting of Fibrinogen

1966 ◽  
Vol 16 (01/02) ◽  
pp. 277-295 ◽  
Author(s):  
A Silver ◽  
M Murray
Keyword(s):  
Amino Acids ◽  
Competitive Inhibition ◽  
Amorphous Material ◽  
Peptide Bond ◽  
Initial Reaction ◽  
Reaction Products ◽  
Coagulation Mechanism ◽  
Kinetics Of ◽  
Kinetics Of Inhibition ◽  
Burk Plot

SummaryVarious investigators have separated the coagulation products formed when fibrinogen is clotted with thrombin and identified fibrinopeptides A and B. Two other peaks are observed in the chromatogram of the products of coagulation, but these have mostly been dismissed by other workers. They have been identified by us as amino acids, smaller peptides and amorphous material (37). We have re-chromatographed these peaks and identified several amino acids. In a closed system of fibrinogen and thrombin, the only reaction products should be fibrin and peptide A and peptide B. This reasoning has come about because thrombin has been reported to be specific for the glycyl-arginyl peptide bond. It is suggested that thrombin also breaks other peptide linkages and the Peptide A and Peptide B are attacked by thrombin to yield proteolytic products. Thrombin is therefore probably not specific for the glycyl-arginyl bond but will react on other linkages as well.If the aforementioned is correct then the fibrinopeptides A and B would cause an inhibition with the coagulation mechanism itself. We have shown that an inhibition does occur. We suggest that there is an autoinhibition to the clotting mechanism that might be a control mechanism in the human body.The experiment was designed for coagulation to occur under controlled conditions of temperature and time. Purified reactants were used. We assembled an apparatus to record visually the speed of the initial reaction, the rate of the reaction, and the density of the final clot formed after a specific time.The figures we derived made available to us data whereby we could calculate and plot the information to show the mechanism and suggest that such an inhibition does exist and also further suggest that it might be competitive.In order to prove true competitive inhibition it is necessary to fulfill the criteria of the Lineweaver-Burk plot. This has been done. We have also satisfied other criteria of Dixon (29) and Bergman (31) that suggest true competitive inhibition.

The Efficient Preparation of Radiolabeled Aromatic Amino Acids via Cu-Mediated Radiofluorination using Ni-complexes

2019 ◽  
Author(s):  
A Craig ◽  
N Kolks ◽  
E Urusova ◽  
BD Zlatopolskiy ◽  
B Neumaier
Keyword(s):  
Amino Acids ◽  
Aromatic Amino Acids

Long term dietary intake of aromatic amino acids are associated with leptin gene expression in adipose tissues of non-diabetic adults

2018 ◽  
Author(s):  
Golaleh Asghari ◽  
Emad Yuzbashian ◽  
Maryam Zarkesh ◽  
Parvin Mirmiran ◽  
Mehdi Hedayati ◽  
...  
Keyword(s):  
Gene Expression ◽  
Amino Acids ◽  
Dietary Intake ◽  
Aromatic Amino Acids ◽  
Adipose Tissues
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