Kinetics of release of amino acids by Leishmania major

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.

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Kinetics and mechanism of oxidation of DL-α-alanine by permanganate ion in acid perchlorate media

Canadian Journal of Chemistry ◽

10.1139/v91-292 ◽

1991 ◽

Vol 69 (12) ◽

pp. 2018-2023 ◽

Cited By ~ 30

Author(s):

Refat M. Hassan

Keyword(s):

Amino Acids ◽

Ionic Strength ◽

Acid Solution ◽

Second Order ◽

Perchloric Acid Solution ◽

Oxidation Reduction ◽

Initial Stage ◽

Aqueous Perchloric Acid ◽

Mechanism Of Oxidation ◽

Kinetics Of

The kinetics of permanganate oxidation of DL-α-alanine in aqueous perchloric acid solution at a constant ionic strength of 2.0 mol dm−3 has been investigated spectrophotometrically. The reaction was found to show second-order kinetics overall with respect to each of the reactants in the slow initial stage; the second-order kinetics are not, however, maintained throughout the relatively fast final stage of reaction. The added salts lead to the prediction that Mn(III) and (or) Mn(IV) play a very important role in the reaction kinetics. A tentative mechanism consistent with the kinetics is discussed. Key words: kinetics, oxidation, reduction, amino acids, permanganate.

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SOME ASPECTS OF THE STRUCTURE OF HEMOGLOBIN

Canadian Journal of Biochemistry ◽

10.1139/o64-087 ◽

1964 ◽

Vol 42 (6) ◽

pp. 755-762 ◽

Cited By ~ 26

Author(s):

David B. Smith

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Amino Acid Sequence ◽

Partial Amino Acid Sequence ◽

Heme Pocket ◽

Terminal Amino ◽

Polypeptide Chains ◽

Kinetics Of ◽

Β Chain

An outline of present ideas concerning the arrangement, folding, and chemistry of the polypeptide chains of hemoglobin is given with some references to present know ledge of myoglobin.New material includes a partial amino acid sequence of the β-chain of horse hemoglobin, details concerning the amino acids lining the heme pocket of horse hemoglobin, and the effects of carboxypeptidases A and B on horse oxy- and horse deoxy-hemoglobin. The kinetics of the latter reactions are not simple. The C-terminal amino acids are released more rapidly from the oxygenated form.

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Identification in skeletal muscle of a distinct extracellular pool of amino acids, and its role in protein synthesis

Biochemical Journal ◽

10.1042/bj1210817 ◽

1971 ◽

Vol 121 (5) ◽

pp. 817-827 ◽

Cited By ~ 74

Author(s):

R. C. Hider ◽

E. B. Fern ◽

D. R. London

Keyword(s):

Skeletal Muscle ◽

Amino Acids ◽

Protein Synthesis ◽

Amino Acid ◽

Incubation Medium ◽

Extensor Digitorum Longus ◽

Extensor Digitorum ◽

Longus Muscle ◽

Kinetics Of

1. The kinetics of radioactive labelling of extra- and intra-cellular amino acid pools and protein of the extensor digitorum longus muscle were studied after incubations with radioactive amino acids in vitro. 2. The results indicated that an extracellular pool could be defined, the contents of which were different from those of the incubation medium. 3. It was concluded that amino acids from the extracellular pool, as defined in this study, were incorporated directly into protein.

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Effects of abomasal infusions of sodium caseinate, a hydrolysate of casein or a corresponding mixture of free amino acids on milk yield and composition in dairy cows

Journal of Dairy Research ◽

10.1017/s0022029900033641 ◽

1995 ◽

Vol 62 (1) ◽

pp. 29-37 ◽

Cited By ~ 15

Author(s):

Jai-Jun Choung ◽

David G. Chamberlain

Keyword(s):

Amino Acids ◽

Dairy Cows ◽

Free Amino Acids ◽

Free Amino ◽

Milk Protein ◽

Bioactive Peptides ◽

Basal Diet ◽

Sodium Caseinate ◽

Amino Acid Residues ◽

Kinetics Of

SummaryThe effects of the form in which amino acids are presented to the abomasum on the milk production of dairy cows receiving a basal diet of grass silage and a barley-based supplement were examined in two experiments. Effects of abomasal infusions of sodium caseinate were compared with the effects of corresponding levels of either an enzymic hydrolysate of casein (Expt 1) or a corresponding mixture of free amino acids (FAA; Expt 2). In Expt 1, although the yield of protein in milk increased progressively with each level of infusion, the yields of protein were greater for the caseinate than for the hydrolysate. Again, in Expt 2, for milk protein yield, sodium caseinate was superior to FAA at the lower level of infusion. In both experiments, the hydrolysate and FAA treatments were associated with higher concentrations of fat in the milk. There were indications of differences in the pattern of secretion of glucagon between the caseinate and FAA treatments. It is concluded that the differences between treatments relate either to the kinetics of absorption of amino acid residues or to the action of bioactive peptides released during digestion of casein.

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Kinetics of oxidation of amino acids by chloramine T. A reinvestigation

Journal of the Chemical Society Perkin Transactions 2 ◽

10.1039/p29850001507 ◽

1985 ◽

pp. 1507 ◽

Cited By ~ 6

Author(s):

M. Shanmugam Ramachandran ◽

T. Subburamiyer Vivekanandam ◽

Rajarathinam Nithyanandhan

Keyword(s):

Amino Acids ◽

Kinetics Of Oxidation ◽

Chloramine T ◽

Kinetics Of

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Determination of protein replacement rates by deuterated water: validation of underlying assumptions

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00488.2006 ◽

2007 ◽

Vol 292 (5) ◽

pp. E1340-E1347 ◽

Cited By ~ 33

Author(s):

Emmanuelle Belloto ◽

Frédérique Diraison ◽

Alexandra Basset ◽

Gwenola Allain ◽

Pauline Abdallah ◽

...

Keyword(s):

Amino Acids ◽

Protein Synthesis ◽

Peripheral Circulation ◽

Deuterated Water ◽

Deuterium Labeling ◽

Kinetics Of ◽

Glycolytic Rate ◽

Slow Turnover ◽

Correct Estimate

H2O administration has recently been proposed as a simple and convenient method to measure protein synthesis rates. 2H2O administration results in deuterium labeling of free amino acids such as alanine, and incorporation into proteins of labeled alanine can then be used to measure protein synthesis rates. We examined first whether during 2H2O administration plasma free alanine enrichment is a correct estimate of the enrichment in the tissue amino acid pools used for protein synthesis. We found that, after 2H2O administration, deuterium labeling in plasma free alanine equilibrated rapidly with body water, and stable enrichment values were obtained within 20 min. Importantly, oral administration of 2H2O induced no difference of labeling between portal and peripheral circulation except for the initial 10 min after a loading dose. The kinetics of free alanine labeling were comparable in various tissues (liver, skeletal muscle, heart) and in plasma with identical plateau values. We show next that increased glycolytic rate or absorption of unlabeled amino acids from ingested meals do not modify alanine labeling. Calculated synthesis rates of mixed proteins were much higher (20- to 70-fold) in plasma and liver than in muscle and heart. Last, comparable replacement rates of apoB100-VLDL were obtained in humans by using the kinetics of incorporation into apoB100 of infused labeled leucine or of alanine labeled by 2H2O administration. All of these results support 2H2O as a safe, reliable, useful, and convenient tracer for studies of protein synthesis, including proteins with slow turnover rate.

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