ENZYMATIC ACTIVATION MECHANISMS

这项计划的两个长期目标涉及机械性 外周膜酶和血色素蛋白的研究。一 目的是为了确定涉及到的分子机制。 外周血丙酮酸氧化酶的激活与调节 催化活性(kcat/Km)增加的膜蛋白 通过与膜小泡结合，约450倍。丙酮酸 氧化酶也可以通过与多种天然的 和合成的磷脂两亲性或通过切割23个氨基 来自羧基末端结构域的残酸多肽(a-肽) 酶的活性。丙酮酸氧化酶的近期目标 项目涉及：1)必需氨基酸的鉴定 A-肽中的残基，推测的膜结合结构域 丙酮酸氧化酶；2)铰链突变体的特性；3) 识别响应脂质的速率限制步骤和 蛋白水解酶的活化，4)活化前后的X射线晶体结构 失活的酶。 这个计划的第二个目标涉及到血蛋白结构- 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和植物过氧化物酶的关系， 过氧化氢酶和P-450细胞色素。氯过氧化物酶是独一无二的 除了催化过氧纳络合过氧化氢酶 和P-450细胞色素。血球蛋白的近期目标 项目包括：1)建筑的三维结构 经X-射线单晶分析确定了氯过氧化物酶的存在； 2)特定活性部位残基的诱变；3)化学物质 过氧化物酶、过氧化氢酶和过氧化氢酶中间体的特性 450个反应；4)卤化物依赖的活化机制 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.