title: Mass spectra of delta 4- and 5 alpha-3-ketosteroids formed during the oxidation of some 3 beta-hydroxysteroids by cholesterol oxidase.
abstract: Thirty-six delta5- and 5'alpha-3beta-hydroxysteroids have been oxidized with cholesterol oxidase to give the corresponding delta4- and 5alpha-3-ketosteroids, respectively. The mass spectral characteristics of the products (or their trimethylsilyl ether derivatives, in the case of 3-keto-hydroxysteroids) varied considerably, depending especially on the nature of the C-17 sidechain. The ion of m/e 124 (or its equivalent) from cleavage of ring B was frequently a major fragment from delta4-3-ketosteroids, but in some instances was of insignificant abundance. Trimethylsilylation of the product of the oxidation of neoergosterol gave neoergosterone enol-trimethylsilyl ether. Fragmentations of the sidechain predominated in the mass spectra of the 5alpha-3-ketosteroids.
mesh_terms: D002784:Cholesterol; D006913:Hydroxysteroid Dehydrogenases / Q000378:metabolism*; D007664:Ketosteroids / Q000032:analysis*; D013058:Mass Spectrometry; D009615:Nocardia / Q000201:enzymology
chemical_list: D007664:Ketosteroids; D002784:Cholesterol; D006913:Hydroxysteroid Dehydrogenases