Cogoli-Greuter M, Hausner U, Christen P
Eur J Biochem. 1979 Oct;100(1):295-300. doi: 10.1111/j.1432-1033.1979.tb02060.x.
Pyruvate decarboxylase from yeast is progressively inactivated in the presence of pyruvate and an extrinsic oxidant such as 2,6-dichloroindophenol or hexacyanoferrate(III). The inactivation is linked to the oxidation of the hydroxyethylthiamine diphosphate intermediate to acetate. Removal of low-molecular compounds by gel filtration does not reactivate the enzyme. The rate of inactivation obeys saturation kinetics with respect to substrate concentration and is independent of enzyme concentration. In analogy to the paracatalytic inactivation of other enzymes forming oxidizable carbanion intermediates [Christen, P. (1977) Methods Enzymol.46, 48--54], the oxidation of enzyme-bound hydroxyethylthiamine diphosphate is thought to generate a transiently reactive intermediate which, without being released from the enzyme, covalently modifies a group at or near the active site. Reconstitution experiments indicate that the protein rather than the coenzyme moiety is modified.
酵母丙酮酸脱羧酶在丙酮酸和诸如2,6 - 二氯靛酚或高铁氰化物（III）等外在氧化剂存在的情况下会逐渐失活。这种失活与羟乙基硫胺二磷酸中间体氧化为乙酸盐有关。通过凝胶过滤去除低分子化合物并不能使酶重新激活。失活速率遵循底物浓度的饱和动力学，且与酶浓度无关。类似于其他形成可氧化碳负离子中间体的酶的副催化失活[克里斯滕，P.（1977年）《酶学方法》46，48 - 54]，与酶结合的羟乙基硫胺二磷酸的氧化被认为会产生一种瞬时反应性中间体，该中间体在不从酶上释放的情况下，共价修饰活性位点处或其附近的一个基团。重组实验表明被修饰的是蛋白质而非辅酶部分。
