Fischl A S, Carman G M
J Bacteriol. 1983 Apr;154(1):304-11. doi: 10.1128/jb.154.1.304-311.1983.
The membrane-associated phospholipid biosynthetic enzyme phosphatidylinositol synthase (cytidine 5'-diphospho-1,2-diacyl-sn-glycerol:myo-inositol 3-phosphatidyltransferase, EC 2.7.8.11) was purified 1,000-fold from the microsomal fraction of Saccharomyces cerevisiae. The purification procedure included Triton X-100 solubilization of the microsomal membranes, CDPdiacylglycerol-Sepharose (Larson et al., Biochemistry 15:974-979, 1976) affinity chromatography, and chromatofocusing. The procedure resulted in the isolation of a nearly homogeneous protein preparation with an apparent minimum subunit molecular weight of 34,000, as determined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Phosphatidylinositol synthase was dependent on manganese and Triton X-100 for maximum activity. The pH optimum was 8.0. Thioreactive agents inhibited enzyme activity. The energy of activation was found to be 35 kcal/mol (146,540 J/mol). The enzyme was reasonably stable at temperatures of up to 60 degrees C.
膜相关磷脂生物合成酶磷脂酰肌醇合成酶（胞苷5'-二磷酸-1,2-二酰基-sn-甘油：肌醇3-磷脂酰转移酶，EC 2.7.8.11）从酿酒酵母的微粒体部分中纯化了1000倍。纯化过程包括用Triton X-100溶解微粒体膜、CDP二酰甘油-琼脂糖（Larson等人，《生物化学》15:974 - 979，1976）亲和色谱和色谱聚焦。该过程得到了一种几乎纯的蛋白质制剂，在十二烷基硫酸钠存在下通过聚丙烯酰胺凝胶电泳测定，其最小亚基表观分子量为34,000。磷脂酰肌醇合成酶的最大活性依赖于锰和Triton X-100。最适pH为8.0。硫反应性试剂抑制酶活性。发现活化能为35千卡/摩尔（146,540焦耳/摩尔）。该酶在高达60摄氏度的温度下相当稳定。
