ENZYMATIC ACTIVATION MECHANISMS

该计划的两个长期目标涉及机械 外周膜酶和血红素蛋白的研究。 一 目的是确定参与的分子机制， 丙酮酸氧化酶的激活和调节， 催化活性（kcat/Km）增加的膜蛋白 约450倍，通过结合到膜囊泡。 丙酮酸 氧化酶也通过与多种天然的 和合成的脂两亲物或通过23个氨基的裂解 来自羧基末端结构域的酸残基肽（a-肽） 的酶。 丙酮酸氧化酶的直接目标 项目内容：1）人体必需氨基酸的鉴定 a-肽中的残基，a-肽中假定的膜结合域， 丙酮酸氧化酶; 2）铰链突变体的表征; 3） 识别响应脂质的速率限制步骤， 蛋白酶活化，4）活化的和 失活酶 该计划的第二个目标涉及血红素蛋白结构- 功能研究主要集中在过氧化物酶的化学上， 最值得注意的是氯过氧化物酶与植物过氧化物酶的关系， 过氧化氢酶和P-450细胞色素。 过氧化物酶是唯一的 过氧化氢酶除了催化过氧化氢化作用外 和P-450细胞色素。 血红素蛋白的直接目标 项目包括：1）三维结构， 用X射线晶体学分析法推测了氯过氧化物酶; 2)特定活性位点残基的诱变; 3）化学物质 过氧化物酶、过氧化氢酶和P- 450反应; 4）卤化物依赖活化的机理 氯过氧化物酶

The two long range objectives of this program involve mechanistic studies on peripheral membrane enzymes and hemoproteins. One objective is to define the molecular mechanisms involved in the activation and regulation of pyruvate oxidase, a peripheral membrane protein whose catalytic activity (kcat/Km) is increased approximately 450-fold by binding to membrane vesicles. Pyruvate oxidase also is activated by bonding to a wide variety of natural and synthetic 1ipid amphiphiles or by the cleavage of a 23 amino acid residue peptide (a-peptide) from the carboxy terminal domain of the enzyme. The immediate goals for the pyruvate oxidase project involve: 1) Identification of essential amino acid residues in the a-peptide, the putative membrane binding domain in pyruvate oxidase; 2) Characterization of hinge mutants; 3) Identification of the rate limit step which responds to lipid and protease activation, 4) X-ray crystal structure of activated and inactivated enzyme. A second objective of this program involves hemoprotein structure- function studies primarily centered on the chemistry of peroxidase, most notable the relation of cholorperoxidase to plant peroxidase, catalase, and P-450 cytochromes. Cholorperoxidase is unique in that in addition to catalyzing peroxidative nalogenation catalase and P-450 cytochromes. The immediate goals of the hemoprotein project include: 1) The three dimensional structure of choloroperoxidase are deduced by X-ray crystallographic analysis; 2) Mutagenesis of specific active site residues; 3) The chemical characterization of intermediates in peroxidase, catalase, and P- 450 reactions; 4) The mechanism of the halide dependent activation of chloroperoxidase.