Squalene synthetase. Solubilization from yeast microsomes of a phospholipid-requiring enzyme.
Squalene synthetase. Solubilization from yeast microsomes of a phospholipid-requiring enzyme.
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发表时间：
1978-07
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通讯作者：
W. Agnew;G. Popják
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作者：
W. Agnew;G. Popják
用脱氧胆酸盐从酵母微粒体膜中溶解角鲨烯合成酶。溶解的酶与一种或多种具有 s20、w = 3.3 S、斯托克斯半径 = 40 A、计算分子量 = 54,500 的蛋白质相关。在洗涤剂存在的情况下，酶没有催化活性并且对热不稳定。当用考来烯胺树脂去除去垢剂时，角鲨烯合成的两个阶段（焦磷酸法尼基导致角鲨烯焦磷酸导致角鲨烯）被回收，并且酶重新聚集以形成密度约为1.16g/ml的可沉降颗粒。在存在 0.2% 脱氧胆酸盐的情况下，在 Sephadex G-200 上进行层析时，这两种活性都不同程度地丧失，但如果在去除洗涤剂之前将磷脂酰胆碱或磷脂酰乙醇胺（但不是磷脂酰丝氨酸或磷脂酰肌醇）添加到级分中，则可以恢复。酶显然对磷脂有绝对的需求。催化角鲨烯合成的两个阶段的蛋白质不能彼此分离，并且在各种操作中以相同的方式表现。
Squalene synthetase was solubilized from yeast microsomal membranes with deoxycholate. Solubilized enzyme was associated with one or more proteins with s20, w = 3.3 S, Stokes' radius = 40 A, and computed molecular weight = 54,500. In the presence of detergent the enzyme was catalytically inactive and unstable to heat. When detergent was removed with cholestyramine resin, both phases of squalene synthesis (farnesyl pyrophosphate leads to presqualene pyrophosphate leads to squalene) were recovered, and the enzyme was reaggregated to form sedimentable particles with a density of approximately 1.16 g/ml. Both activities were lost to variable extent upon chromatography over Sephadex G-200 in the presence of 0.2% deoxycholate, but could be recovered if phosphatidylcholine or phosphatidylethanolamine (but not phosphatidylserine or phosphatidylinositol) were added to fractions before removal of detergent. There was an apparently absolute requirement for phospholipid by the enzyme. The proteins catalyzing the two phases of squalene synthesis could not be resolved from one another and behaved in an identical fashion throughout a variety of manipulations.