PROTEIN LIPID INTERACTION

这项建议的目标是了解 亲水性可溶性蛋白与膜相互作用，特别是 膜脂成分。最近的研究表明，许多这样的 相互作用存在并扮演着多种细胞角色，如感官 转导。然而，人们对其中涉及的机制知之甚少。 我们将研究两种酶系统。两者都是细菌的酶， 大肠埃希菌。大肠杆菌丙酮酸氧化酶是一种重要的酶 与脂类结合后被激活(在Kcat中是500倍)，但是一种可溶性的 与氨基酸生物合成的某些酶密切相关的蛋白质。 先前的工作已经为这种相互作用提出了一个模型，根据该模型，C- 酶的末端穿透到脂双层中，这一模型 应通过生化和遗传手段进行检测。开发一种新的 提出了一种测定蛋白质透过性的方法。 第二种酶是大肠杆菌环丙烷脂肪酸合成酶，a 一种新型的修饰驻留在磷脂中的双键酶 一种脂双层。CFA合成酶使双键甲基化，形成一个 环丙烷环，亚甲基给体为S-腺苷甲硫氨酸。这个 纯化的酶及其与磷脂的相互作用现已问世 现在可以进行详细的研究了。

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.