[Steroid-transforming enzymes from microorganisms. X. Enrichment of a 4-en-3-oxosteroid-5 alpha-reductase from Mycobacterium smegmatis as well as separation and enrichment of the apoenzyme by means of affinity chromatography].

The 4-en-3-oxosteroid-5 alpha-reductase from Mycobacterium smegmatis was bound biospecifically on the affinant containing an immobilized testosterone ligand. The enzyme obtained by elution with ethylene glycol and urea in a 32 fold purity has a S. A. of 8.73 X 10(-3) microM androstenedione min-1 mg-1. The coenzyme (FAD) could be separated from the immobilized enzyme substrate complex on the affinity matrix, in the presence of (NH4)2SO4 at pH 3.0. After elution of the apoenzyme 97% of the initial enzyme activity was obtained by incubation with FAD. The reactivated enzyme results in a 40-fold enrichment.