Thurnhofer H, Gains N, Mütsch B, Hauser H
Biochim Biophys Acta. 1986 Mar 27;856(1):174-81. doi: 10.1016/0005-2736(86)90024-6.
Cholesterol present in intact brush-border membrane vesicles made from rabbit small intestine is a poor substrate for cholesterol oxidase (EC 1.1.3.6, from Nocardia sp. and Nocardia erythropolis). It becomes susceptible to oxidation by the enzyme only after the addition of detergent, e.g., Triton X-100, in quantities sufficient to disrupt the membrane. This is also true for cholesterol present in bilayers of small unilamellar phosphatidylcholine or phosphatidylserine vesicles made by ultrasonication. The data presented here on intestinal brush-border membrane are in good agreement with results reported on other biological membranes, e.g., from erythrocytes and vesicular stomatitis virus, but are somewhat different from those on rat intestinal brush-border membrane. Our results on phospholipid bilayers agree well with published work on model membranes. From the work presented we conclude that, with our present understanding, cholesterol oxidase can hardly be used to probe the distribution of cholesterol in biological membranes. A prerequisite for using the enzyme successfully as such a probe would be the understanding of the factors controlling the interaction of the enzyme with its substrate cholesterol. The question under which conditions cholesterol oxidase could be useful for probing the distribution and preferred location of cholesterol in biological membranes is discussed.
由兔小肠制成的完整刷状缘膜囊泡中存在的胆固醇，对于胆固醇氧化酶（来自诺卡氏菌属和红色诺卡氏菌的EC 1.1.3.6）而言是一种较差的底物。只有在加入足以破坏膜结构的去污剂（如Triton X - 100）后，它才会变得易于被该酶氧化。对于通过超声处理制成的小单层磷脂酰胆碱或磷脂酰丝氨酸囊泡双层中存在的胆固醇，情况也是如此。此处关于肠刷状缘膜的数据与其他生物膜（如红细胞和水泡性口炎病毒的生物膜）所报道的结果高度一致，但与大鼠肠刷状缘膜的数据有所不同。我们关于磷脂双层的结果与已发表的关于模型膜的研究结果吻合良好。从所呈现的研究工作中我们得出结论，就我们目前的认知而言，胆固醇氧化酶几乎无法用于探测生物膜中胆固醇的分布。要成功地将该酶用作这样一种探针，前提是要了解控制该酶与其底物胆固醇相互作用的因素。本文讨论了在哪些条件下胆固醇氧化酶可用于探测生物膜中胆固醇的分布和优先定位。
