Chenas N K, Butkus A A, Kanapenene Iu Iu, Kulis Iu Iu
Ukr Biokhim Zh (1978). 1987 Mar-Apr;59(2):44-9.
Lipoamide dehydrogenase (EC 1.6.4.3) from the ketoglutarate dehydrogenase complex of adrenals catalyzes the oxidation of NADH by lipoamide and quinone compounds according to the "ping-pong" scheme. The catalytic constants of these reactions are equal to 220 and 24 s-1, respectively (pH 7.0). The maximal quinone reductase activity is observed at pH 5.6, whereas the lipoamide reductase activity changes insignificantly at pH 7.5-5.5. The maximal dihydrolipoamide-NAD+ reductase activity is observed at pH 7.8. The oxidative constants of quinone electron acceptors vary from 6 X 10(6) to 4 X 10(2) M-1 s-1 and increase with their redox potential. The patterns of NAD+ inhibition in the quinone reductase reaction differ from that of lipoamide reductase reaction. The quinones are reduced by lipoamide dehydrogenase in the one-electron mechanism.
肾上腺α-酮戊二酸脱氢酶复合体中的硫辛酰胺脱氢酶（EC 1.6.4.3）根据“乒乓”机制催化硫辛酰胺和醌类化合物氧化NADH。这些反应的催化常数分别为220和24 s-1（pH 7.0）。醌还原酶的最大活性在pH 5.6时观察到，而硫辛酰胺还原酶活性在pH 7.5 - 5.5时变化不显著。二氢硫辛酰胺-NAD+还原酶的最大活性在pH 7.8时观察到。醌电子受体的氧化常数在6×10(6)至4×10(2) M-1 s-1之间变化，并随其氧化还原电位增加。醌还原酶反应中NAD+抑制模式与硫辛酰胺还原酶反应不同。醌类通过单电子机制被硫辛酰胺脱氢酶还原。
