What question did this study set out to answer?

To determine the kinetic parameters and membrane-binding properties governing the activation of normal versus gamma-carboxyglutamic acid (Gla)-deficient prothrombins.

January 1, 1985Journal of Biological ChemistryOpen Access

The kinetics of activation of normal and gamma-carboxyglutamic acid-deficient prothrombins.

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Authors

OMO.P. MalhotraUniversity of Vermont MNMichael E. NesheimCleveland State University KMKenneth G. MannVascular / Pulmonary Vascular

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Implication

In vitro kinetic analysis reveals impaired activation kinetics for gamma-carboxyglutamic acid-deficient prothrombins in bovine plasma, indicating a steep threshold for membrane binding.

Key Points

To determine the kinetic parameters and membrane-binding properties governing the activation of normal versus gamma-carboxyglutamic acid (Gla)-deficient prothrombins.
Purified normal (10-Gla) and Gla-deficient prothrombin variants containing 0, 1, 2, 5, or 7 Gla residues from cattle treated chronically with the vitamin K antagonist dicoumarol.
Assayed activation rates using prothrombinase complex (Factor Xa, Factor Va, phospholipid vesicles, and Ca2+) via initial rate and integrated Michaelis-Menten-Henri analyses.
All Gla-deficient prothrombin variants exhibited catalytic rate constants (kcat) similar to normal 10-Gla prothrombin, but showed an 8- to 20-fold increase in Km.
The kinetic defect and loss of Ca2+- and phospholipid-binding manifested abruptly upon the loss of as few as 3 of the 10 Gla residues, corresponding to a 100- to 1000-fold decrease in phospholipid affinity.
Activation products generated from normal 10-Gla prothrombin exerted an inhibitory effect on the activation of Gla-deficient prothrombin species.

Cite This Study

Malhotra et al. (1985) studied this question.

synapsesocial.com/papers/6a1c9589973ffece4bc403d4 https://doi.org/10.1016/s0021-9258(18)89728-9

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Implication

In vitro kinetic analysis reveals impaired activation kinetics for gamma-carboxyglutamic acid-deficient prothrombins in bovine plasma, indicating a steep threshold for membrane binding.

The kinetics of activation of normal and gamma-carboxyglutamic acid-deficient prothrombins.

Discussion

Member takes

Implication

Key Points

Cite This Study

The kinetics of activation of normal and gamma-carboxyglutamic acid-deficient prothrombins.

Discussion

Member takes

Implication

Key Points

Cite This Study

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