双功能脱氢酶L-组氨醇：NAD⁺氧化还原酶的产物抑制模式

Patterns of product inhibition of a bifunctional dehydrogenase; L-histidinol:NAD+ oxidoreductase.

作者信息

Bürger E, Görisch H

出版信息

Eur J Biochem. 1981 May;116(1):137-42. doi: 10.1111/j.1432-1033.1981.tb05311.x.

DOI:10.1111/j.1432-1033.1981.tb05311.x

Abstract

The steady-state kinetic patterns of the bifunctional enzyme histidinol dehydrogenase from Salmonella typhimurium (EC 1.1.1.23) are compatible with a bi-uni uni-bi ping-pong mechanism. Studies of product inhibition make it possible to determine the sequence of substrate binding and product dissociation. Histidinol binds first to the enzyme, followed by the binding of NAD+; histidine is the last product to dissociate from histidinol dehydrogenase. Five of ten kinetic constants defined are determined from linear intercept and slope replots; Km for histidinol was found to be 16 +/- 3 microM and for NAD+ 1 +/- 0.3 mM; K2 for NAD+ was determined to be 0.8 +/- 0.4 mM and K3 for NADH to be 0.3 +/- 0.07 mM. K1 for histidine was found to be 2.1 +/- 0.5 mM.

摘要

鼠伤寒沙门氏菌双功能酶组氨醇脱氢酶（EC 1.1.1.23）的稳态动力学模式符合双单-单双乒乓机制。产物抑制研究使得确定底物结合和产物解离的顺序成为可能。组氨醇首先与酶结合，随后是NAD⁺的结合；组氨酸是最后从组氨醇脱氢酶上解离的产物。所定义的十个动力学常数中有五个是通过线性截距和斜率重绘图确定的；组氨醇的Km值为16±3微摩尔，NAD⁺的Km值为1±0.3毫摩尔；NAD⁺的K2值为0.8±0.4毫摩尔，NADH的K3值为0.3±0.07毫摩尔。组氨酸的K1值为2.1±0.5毫摩尔。