Substrate stereospecificity in oxidation of (25S)-3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholestanoyl-CoA by peroxisomal trihydroxy-5 beta-cholestanoyl-CoA oxidase.
Partly purified 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholestanoyl-CoA oxidase from rabbit liver peroxisomes was found to convert the 25S- but not the 25R diastereoisomer of 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholestan-27-oyl-CoA into (24E)-3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholest-24-en-27-oic acid. In the presence of a peroxisomal THCA-CoA racemase, however, also the 25R isomer was oxidized. Since the mitochondrial steroid-27-hydroxylase, responsible for formation of THCA, is 25R specific a racemase seems to be obligatory for formation of cholic acid by the normal peroxisomal-dependent pathway.
Pedersen
J I
JI
Institute for Nutrition Research, School of Medicine, University of Oslo, Norway.
Veggan
T
T
Björkhem
I
I
D000214:Acyl Coenzyme A / Q000378:metabolism*; D000818:Animals; D002777:Cholestanols / Q000378:metabolism*; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008297:Male; D008830:Microbodies / Q000201:enzymology*; D008930:Mitochondria, Liver / Q000201:enzymology; D010088:Oxidoreductases / Q000378:metabolism*; D011817:Rabbits; D013237:Stereoisomerism; D013379:Substrate Specificity
D000214:Acyl Coenzyme A; D002777:Cholestanols; C074626:3,7,12-trihydroxycholestan-26-oyl-CoA; D010088:Oxidoreductases; C066160:trihydroxycholestanoyl-CoA oxidase