Peroxisomal beta-oxidation of 2-methyl-branched acyl-CoA esters: Stereospecific recognition of the 2S-methyl compounds by trihydroxycoprostanoyl-CoA oxidase and pristanoyl-CoA oxidase
Peroxisomal beta-oxidation of 2-methyl-branched acyl-CoA esters: Stereospecific recognition of the 2S-methyl compounds by trihydroxycoprostanoyl-CoA oxidase and pristanoyl-CoA oxidase
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DOI：
10.1016/0014-5793(96)00508-x
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发表时间：
1996-06-10
期刊：
影响因子：
3.5
通讯作者：
Mannaerts, GP
中科院分区：
文献类型：
--
作者：
VanVeldhoven, PP;Croes, K;Mannaerts, GP
从大鼠肝脏中纯化的三羟基coprostanyl - coa氧化酶和pristanyl - coa氧化酶都能催化2-甲基支链酰基辅酶a的去饱和。与2-甲基戊烷酰辅酶a纯异构体孵育后，两种酶仅作用于s -异构体，r -异构体抑制三羟基coprostanyl - coa氧化酶，但不影响pristanyl - coa氧化酶，3-甲基庚烷酰辅酶a抑制两种酶的活性。然而，丙戊酰辅酶a和2-乙基己烯酰辅酶a对氧化酶没有影响，尽管25R只有一个异构体s -三羟基辅酶辅酶a被三羟基辅酶a氧化酶去饱和，但分离的过氧化物酶体能够作用于这两个异构体，这表明在这些细胞器中存在消旋酶。考虑到26-胆固醇羟化酶和氧化酶的相反立体选择性，消旋酶对胆囊酸的形成至关重要。
Trihydroxycoprostanoyl-CoA oxidase and pristanoyl-CoA oxidase, purified from rat liver, both catalyse the desaturation of 2-methyl-branched acyl-CoAs. Upon incubation with the pure isomers of 2-methylpentadecanoyl-CoA, both enzymes acted only on the S-isomer, The R-isomer inhibited trihydroxycoprostanoyl-CoA oxidase but did not affect pristanoyl-CoA oxidase, The activity of both enzymes was suppressed by 3-methylheptadecanoyl-CoA. Valproyl-CoA and 2-ethylhexanoyl-CoA, however, did not influence the oxidases, Although only one isomer of 25R,S-trihydroxycoprostanoyl-CoA was desaturated by trihydroxycoprostanoyl-CoA oxidase, isolated peroxisomes were able to act on both isomers, suggesting the presence of a racemase in these organelles, Given the opposite stereoselectivity of the 26-cholesterol hydroxylase and of the oxidase, the racemase is essential for bile acid formation.