Monder C, Purkaystha AR, Pietruszko R. Oxidation of the 17-aldol (20 beta hydroxy-21-aldehyde) intermediate of corticosteroid metabolism to hydroxy acids by homogeneous human liver aldehyde dehydrogenases.
JOURNAL OF STEROID BIOCHEMISTRY 1982;
17:41-9. [PMID:
7109591 DOI:
10.1016/0022-4731(82)90590-8]
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Abstract
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.
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