The argenine residue in the active-site of D-glyceralde-hyde-3-phosphate dehydrogenase - participation in individual steps of catalysisстатья
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Дата последнего поиска статьи во внешних источниках: 27 мая 2015 г.
Местоположение издательства:Road Town, United Kingdom
Первая страница:701
Последняя страница:706
Аннотация:The chemical modification of one arginine residue per subunit of the tetramer D-glyceraldehyde-3-phosphate dehydrogenase molecule leads to an 85-95% loss of activity [1, 2]. An investigation of the presteady-state reaction kinetics, conducted in this work with native and modified enzymes from baker's yeast, showed that modifications of the arginine residue induces a 60-fold decrease in the reaction rate constant of formation of the complex 3-phosphoglyceroyl-enzyme.NADH. A 40-fold decrease in the rate constant of phosphorolysis of the acyl-enzyme is also observed. In experiments on the competitive inhibition of the oxidation of 3-phosphoglyceraldehyde in the presence of NADH, results permitting exclusion of the participation of the arginine residue in the destabilization of the acyl-enzyme.NADH complex were obtained. The results of this work experimentally confirm the major premises of the hypothesis on the role of the arginine residue in the catalytic mechanism of D-glyceraldehyde-3-phosphate dehydrogenase, advanced on the basis of x-ray crystallographic data [3, 4], and agree with the concept of a similar function of this residue in the active sites of various NAD+-dependent dehydrogenases.