Bunik V I, Buneeva O A, Gomazkova V S
Biokhimiia. 1991 Apr;56(4):694-706.
The redox state of two SH-groups per enzyme subunit has been shown to control the cooperative properties of alpha-ketoglutarate dehydrogenase. These thiols oxidized, alpha-ketoglutarate dehydrogenase does not exhibit any cooperative properties. The enzyme reduction leads to subunit interactions. It has been found that the most effective agent reducing the alpha-ketoglutarate dehydrogenase thiols essential for the cooperativity is dihydrolipoate, one of the intermediates of the overall alpha-ketoglutarate dehydrogenase reaction. The possibility of changing the properties of alpha-ketoglutarate dehydrogenase in the multienzyme complex under the conditions when the lipoic acid integrated into the complex is reduced, has been investigated. Thus, incubation of the alpha-ketoglutarate dehydrogenase complex with NADH has been found to induce the conversion from the non-cooperative form to the cooperative one, presumably through the reduction of lipoic acid bound to the complex in the reaction catalyzed by lipoyl dehydrogenase, the third component of the complex.
已表明每个酶亚基的两个巯基的氧化还原状态可控制α-酮戊二酸脱氢酶的协同性质。这些巯基被氧化时，α-酮戊二酸脱氢酶不表现出任何协同性质。酶的还原会导致亚基相互作用。已发现，对协同性至关重要的还原α-酮戊二酸脱氢酶巯基的最有效试剂是二氢硫辛酸，它是整个α-酮戊二酸脱氢酶反应的中间体之一。在多酶复合物中，当整合到复合物中的硫辛酸被还原时，研究了改变α-酮戊二酸脱氢酶性质的可能性。因此，已发现α-酮戊二酸脱氢酶复合物与NADH一起温育会诱导从非协同形式转变为协同形式，推测是通过在复合物的第三个组分硫辛酰胺脱氢酶催化的反应中还原与复合物结合的硫辛酸来实现的。
