Casteels M, Schepers L, Van Veldhoven P P, Eyssen H J, Mannaerts G P
Afdeling Farmakologie, Katholieke Universiteit Leuven, Belgium.
J Lipid Res. 1990 Oct;31(10):1865-72.
Fatty acyl-CoAs as well as the CoA esters of the bile acid intermediates di- and trihydroxycoprostanic acids are beta-oxidized in peroxisomes. The first reaction of peroxisomal beta-oxidation is catalyzed by acyl-CoA oxidase. We recently described the presence of two fatty acyl-CoA oxidases plus a trihydroxycoprostanoyl-CoA oxidase in rat liver peroxisomes (Schepers, L., P. P. Van Veldhoven, M. Casteels, H. J. Eyssen, and G. P. Mannaerts. 1990. J. Biol. Chem. 265: 5242-5246). We have now developed methods for the measurement of palmitoyl-CoA oxidase and trihydroxycoprostanoyl-CoA oxidase in human liver. The activities were measured in livers from controls and from three patients with peroxisomopathies. In addition, the oxidase activities were partially purified from control livers by ammonium sulfate fractionation and heat treatment, and the partially purified enzyme preparation was subjected to chromatofocusing, hydroxylapatite chromatography, and gel filtration. In earlier experiments this allowed for the separation of the three rat liver oxidases. The results show that human liver, as rat liver, contains a separate trihydroxycoprostanoyl-CoA oxidase. In contrast to the situation in rat liver, no conclusive evidence was obtained for the presence of two fatty acyl-CoA oxidases in human liver. Our results explain why bile acid metabolism is normal in acyl-CoA oxidase deficiency, despite a severely disturbed peroxisomal fatty acid oxidation and perhaps also why, in a number of other cases of peroxisomopathy, di- and trihydroxycoprostanic acids are excreted despite a normal peroxisomal fatty acid metabolism.
脂肪酰辅酶A以及胆汁酸中间体二羟基和三羟基粪甾烷酸的辅酶A酯在过氧化物酶体中进行β氧化。过氧化物酶体β氧化的第一步反应由酰基辅酶A氧化酶催化。我们最近描述了大鼠肝脏过氧化物酶体中存在两种脂肪酰辅酶A氧化酶以及一种三羟基粪甾烷酰辅酶A氧化酶（Schepers, L., P. P. Van Veldhoven, M. Casteels, H. J. Eyssen, and G. P. Mannaerts. 1990. J. Biol. Chem. 265: 5242 - 5246）。我们现已开发出测定人肝脏中棕榈酰辅酶A氧化酶和三羟基粪甾烷酰辅酶A氧化酶的方法。在对照组以及三名过氧化物酶体病患者的肝脏中测定了这些酶的活性。此外，通过硫酸铵分级分离和热处理从对照肝脏中部分纯化了氧化酶活性，并对部分纯化的酶制剂进行了色谱聚焦、羟基磷灰石色谱和凝胶过滤。在早期实验中，这使得能够分离出三种大鼠肝脏氧化酶。结果表明，人肝脏与大鼠肝脏一样，含有一种单独的三羟基粪甾烷酰辅酶A氧化酶。与大鼠肝脏的情况相反，没有获得确凿证据表明人肝脏中存在两种脂肪酰辅酶A氧化酶。我们的结果解释了为什么在酰基辅酶A氧化酶缺乏症中胆汁酸代谢正常，尽管过氧化物酶体脂肪酸氧化严重紊乱，也许还解释了为什么在许多其他过氧化物酶体病病例中，尽管过氧化物酶体脂肪酸代谢正常，但二羟基和三羟基粪甾烷酸仍会排泄。
