PROTEIN LIPID INTERACTION

本提案的目的是了解 亲水性可溶性蛋白质与膜相互作用，特别是 膜脂成分 最近的研究表明， 相互作用存在，并发挥多种细胞作用，如感觉 转导 然而，人们对所涉及的机制知之甚少。 将研究两种酶系统。 两者都是细菌的酶， 大肠埃希菌 E.大肠杆菌丙酮酸氧化酶是一种酶， 在与脂质结合时活化（Kcat中为500倍），但为可溶性 与某些氨基酸生物合成酶密切相关的蛋白质。 先前的工作提出了这种相互作用的模型，其中C- 酶的末端渗透到脂质双层中，并且该模型 须以生物化学及遗传学方法进行测试。 发展新 提出了一种测定蛋白质穿透脂质双层的方法。 第二种酶是E。大肠杆菌环丙烷脂肪酸（CFA）合酶， 一种修饰磷脂双键的新酶， 脂质双层。 CFA合酶使双键亚甲基化以形成 环丙烷环，亚甲基供体是S-腺苷甲硫氨酸。 的 纯化的酶现在可用，其与磷脂的相互作用 现在可以详细研究。

The objectives of this proposal is to understand the mechanism whereby hydrophilic soluble proteins interact with membranes, specifically the membrane lipid component. Recent work indicates that many such interactions exist and play a multitude of cell roles such as sensory transduction. However, little is known about the mechanisms involved. Two enzyme systems will be studied. Both are enzymes of the bacterium, Escherichia coli. E. coli pyruvate oxidase is an enzyme greatly activated (500-fold in Kcat) upon binding to lipids, but is a soluble protein closely related to certain enzymes of amino acids biosynthesis. Prior work has suggested a model for this interaction whereby the C- termini of the enzyme penetrates into the lipid bilayer and this model shall be tested by biochemical and genetic means. Development of a new method to assay penetration of proteins into a lipid bilayer is proposed. The second enzyme is E. coli cyclopropane fatty acid (CFA) synthase, a novel enzyme that modifies the double bonds of phospholipids resident in a lipid bilayer. CFA synthase methylenates the double bond to form a cyclopropane ring, the methylene donor being S-adenosyl methionine. The purified enzyme is now available and its interaction with phospholipids can now be studied in detail.