Kase B F, Prydz K, Björkhem I, Pedersen J I
Biochim Biophys Acta. 1986 Jun 11;877(1):37-42. doi: 10.1016/0005-2760(86)90115-3.
The conversion of 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-[3H]cholestanoic acid into cholic acid and 3 alpha,7 alpha-dihydroxy-5 beta-[3H]cholestanoic acid into chenodeoxycholic acid has been studied in subcellular fractions of human liver. The products were separated from the substrates by high-pressure liquid chromatography and identified by combined gas chromatography-mass spectrometry. The highest rates of conversion were found in the light mitochondrial fraction. This fraction also contained the highest amount of the marker enzymes for peroxisomes. The maximal rates of cholic acid and chenodeoxycholic acid formation were 1.3 and 1.8 nmol/mg protein per h, respectively. The presence of KCN in the incubation medium stimulated the formation of bile acids. Peroxisomes were prepared from the light mitochondrial fraction by sucrose-gradient centrifugation. By use of different marker enzymes, it was confirmed that the major part of the activity for cholic acid formation in the light mitochondrial fraction was located in the peroxisomes. It is concluded that liver peroxisomes are important for the oxidative cleavage of the C27 steroid side chain in bile acid formation in man.
在人肝脏的亚细胞组分中研究了3α,7α,12α-三羟基-5β-[3H]胆甾烷酸转化为胆酸以及3α,7α-二羟基-5β-[3H]胆甾烷酸转化为鹅去氧胆酸的过程。通过高压液相色谱将产物与底物分离，并通过气相色谱-质谱联用进行鉴定。在轻线粒体组分中发现了最高的转化率。该组分还含有最高量的过氧化物酶体标记酶。胆酸和鹅去氧胆酸形成的最大速率分别为每小时每毫克蛋白质1.3和1.8 nmol。孵育培养基中存在氰化钾会刺激胆汁酸的形成。通过蔗糖梯度离心从轻线粒体组分中制备过氧化物酶体。利用不同的标记酶证实，轻线粒体组分中胆酸形成活性的主要部分位于过氧化物酶体中。得出的结论是，肝脏过氧化物酶体对人类胆汁酸形成过程中C27甾体侧链的氧化裂解很重要。
