Substrate specificity of THCA-CoA oxidases from rat liver light mitochondrial fractions on dehydrogenation of 3α,7α,12α-trihydroxy-5β-cholestanoic acid CoA thioester
Substrate specificity of THCA-CoA oxidases from rat liver light mitochondrial fractions on dehydrogenation of 3α,7α,12α-trihydroxy-5β-cholestanoic acid CoA thioester
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DOI：
10.1016/s0039-128x(98)00070-1
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发表时间：
1998-11-01
期刊：
影响因子：
2.7
通讯作者：
Goto, J
中科院分区：
文献类型：
--
作者：
Ikegawa, S;Goto, T;Goto, J
大鼠肝过氧化物酶体3 α，7 α，12 α-三羟基-5 β-胆甾烷酰辅酶A的底物特异性（THCA-CoA）氧化酶，其催化在C-25处具有不对称中心的3 α，7 α，12 α-三羟基-5 β-胆甾烷酸（THCA）CoA硫酯脱氢以形成（24 E）-3 α，7 α，研究的12 α-三羟基-5 β-胆甾-24-烯酸（Delta（24）-THCA）CoA硫酯，铱。通过3，7，12-三氧-5 β-胆甾烷酸甾核上的羰基氧交换反应，然后通过金属氢化物还原和与CoA的缩合反应，合成了稳定同位素标记的底物[3，7，12-O-18（3）]-（25 R）-和（25 S）-THCA CoA硫酯。将未标记的（25 R）-和O-18-标记的（25 S）-THCA CoA硫酯（或反之亦然）的混合物与肝过氧化物酶体THCA-CoA氧化酶孵育后，通过液相色谱/大气压化学电离质谱法测定生物转化的Δ（24）-THCA。Δ（24）-THCA仅衍生自（25 S）-THCA CoA硫酯，表明THCA的25 S差向异构体是THCA-CoA氧化酶脱氢的优先底物。（类固醇63：603607，1998）（C）1998，Elsevier Science Inc.
The substrate specificity of rat liver peroxisomal 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestanoyl-CoA (THCA-CoA) oxidases, which catalyze the dehydrogenation of 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestanoic acid (THCA) CoA thioester, having an asymmetric center at C-25, to form (24E)-3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholest-24-enoic acid (Delta(24)-THCA) CoA thioester, Ir as studied. The stable isotope labeled substrates, [3,7,12-O-18(3)]-(25R)- and (25S)-THCA CoA thioesters were synthesized by an exchange reaction of carbonyl oxygens on a steroid nucleus of 3,7,12-trioxo-5 beta-cholestanoic acid, followed by metal hydride reduction and condensation reaction with CoA. After incubation of a mixture of unlabeled (25R)- and O-18-labeled (25S)-THCA CoA thioester, or vice versa, with hepatic peroxisomal THCA-CoA oxidases, biotransformed Delta(24)-THCA was determined by liquid chromatography/ atmospheric pressure chemical ionization mass spectrometry. The Delta(24)-THCA was derived only from (25S)-THCA CoA thioester, indicating that the 25S epimer of THCA is a preferential substrate on dehydrogenation by THCA-CoA oxidases. (Steroids 63:603607, 1998) (C) 1998 by Elsevier Science Inc.