Klezovitch O, Brandenburger Y, Geindre M, Deshusses J
Department of Biochemistry, University of Geneva, Switzerland.
FEBS Lett. 1993 Apr 12;320(3):256-60. doi: 10.1016/0014-5793(93)80598-o.
The nature of reactions catalysed by yeast phosphatidylinositol synthase expressed in E. coli has been investigated. The single enzyme is shown to carry both CDP-diacylglycerol-dependent incorporation of inositol into phosphatidylinositol (Km for inositol of 0.090 mM) and a CDP-diacylglycerol-independent exchange reaction between phosphatidylinositol and inositol (Km for inositol of 0.066 mM). The exchange reaction and reversal of phosphatidylinositol synthase were both stimulated by CMP, but had different optimum pH and requirements for substrates. These results suggest that CMP-stimulated exchange and CMP-dependent reverse reactions are distinct processes catalysed by the same enzyme, phosphatidylinositol synthase.
对在大肠杆菌中表达的酵母磷脂酰肌醇合酶所催化反应的性质进行了研究。结果表明，单一的这种酶既能催化依赖CDP - 二酰甘油将肌醇掺入磷脂酰肌醇（肌醇的Km为0.090 mM），又能催化磷脂酰肌醇和肌醇之间不依赖CDP - 二酰甘油的交换反应（肌醇的Km为0.066 mM）。CMP能刺激交换反应以及磷脂酰肌醇合酶的逆转反应，但它们具有不同的最适pH值和底物需求。这些结果表明，CMP刺激的交换反应和CMP依赖的逆转反应是由同一酶——磷脂酰肌醇合酶催化的不同过程。
