Monder C, Purkaystha A R, Pietruszko R
J Steroid Biochem. 1982 Jul;17(1):41-9. doi: 10.1016/0022-4731(82)90590-8.
In human liver, the oxidation of corticosteroids to 20-hydroxy-21-oic acids proceeds via the formation and oxidation of aldol (20-hydroxy-21-aldehyde) intermediates. Human liver aldehyde dehydrogenases E1 and E2, which we have previously purified to homogeneity, catalyzed the oxidation of the aldol isomer of cortisol (isocortisol) or of 11-deoxycorticosterone (isoDOC) by E1 and E2 respectively, were identified by the criteria of chromatographic mobility, derivatization, and reverse isotope dilution of 4-14C labeled acid end products. Both enzymes showed broad substrate specificity and oxidized both 17-hydroxy and 17-deoxy steroids, though at widely varying rates. Kinetic analysis of the course of oxidation of isocortisol and isoDOC by NAD+ gave intersecting initial velocity plots that conform with a sequential mechanism. The inhibition patterns for both enzymes with thionicotinamide adenine dinucleotide or chloral hydrate were consistent with random sequential behavior.
在人肝脏中，皮质类固醇氧化为20-羟基-21-酸是通过醛醇（20-羟基-21-醛）中间体的形成和氧化进行的。我们之前已纯化至同质的人肝脏醛脱氢酶E1和E2，分别催化皮质醇（异皮质醇）或11-脱氧皮质酮（异脱氧皮质酮）的醛醇异构体的氧化，通过色谱迁移率、衍生化以及4-¹⁴C标记酸终产物的反向同位素稀释标准进行鉴定。两种酶均表现出广泛的底物特异性，并且能氧化17-羟基和17-脱氧类固醇，不过氧化速率差异很大。用NAD⁺对异皮质醇和异脱氧皮质酮的氧化过程进行动力学分析，得到相交的初速度图，符合有序机制。两种酶对硫代烟酰胺腺嘌呤二核苷酸或水合氯醛的抑制模式与随机有序行为一致。
