Abstract
The substrate specificity of rat liver peroxisomal 3α,7α,12α-trihydroxy-5β-cholestanoyl-CoA (THCA-CoA) oxidases, which catalyze the dehydrogenation of 3α,7α,12α-trihydroxy-5β-cholestanoic acid (THCA) CoA thioester, having an asymmetric center at C-25, to form (24 E)-3α,7α,12α-trihydroxy-5β-cholest-24-enoic acid (Δ 24-THCA) CoA thioester, was studied. The stable isotope labeled substrates, [3,7,12- 18O 3]-(25 R)- and (25 S)-THCA CoA thioesters were synthesized by an exchange reaction of carbonyl oxygens on a steroid nucleus of 3,7,12-trioxo-5β-cholestanoic acid, followed by metal hydride reduction and condensation reaction with CoA. After incubation of a mixture of unlabeled (25 R)- and 18O-labeled (25 S)-THCA CoA thioester, or vice versa, with hepatic peroxisomal THCA-CoA oxidases, biotransformed Δ 24-THCA was determined by liquid chromatography/atmospheric pressure chemical ionization mass spectrometry. The Δ 24-THCA was derived only from (25 S)-THCA CoA thioester, indicating that the 25 S epimer of THCA is a preferential substrate on dehydrogenation by THCA-CoA oxidases.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
