STRUCTURE AND MECHANISM OF PLP-DEPENDENT ENZYMES

吡哆醛-5‘-磷酸(PLP)是许多酶的辅因子 进行广泛的氨基酸和氨基酸的生物转化 胺，包括转氨基、脱羧基、β-和伽马- 淘汰赛。PLP能够执行这些反应中的许多在 以低得多的比率缺乏脱脂蛋白基质 区域特异性和立体特异性。我们提出的研究的目标是 是为了确定三种PLP反应的分子细节- 依赖酶：L)大肠杆菌色氨酸吲哚裂解酶；2)酪氨酸 柠檬酸杆菌的苯酚裂解酶；3)假单胞菌的犬尿氨酸酶 荧光灯。我们特别感兴趣的是研究 蛋白质基质中提供底物和反应的特异性 这些酶。这些研究将利用X射线晶体结构 测定、快速反应动力学测量和现场定向 酶的诱变。

Pyridoxal-5'-phosphate (PLP) is the cofactor for a large number of enzymes performing a wide range of biological transformations of amino acids and amines, including transaminations, decarboxylations, and beta- and gamma- eliminations. PLP is capable of performing many of these reactions in the absence of an apoprotein matrix at much lower rates and without regiospecificity and stereospecificity. The goal of our proposed research is to determine the molecular details of the reactions of three PLP- dependent enzymes: l) Tryptophan indole-lyase from E. coli; 2) Tyrosine phenol-lyase from Citrobacter; and 3) Kynureninase from Pseudomonas fluorescens. We are especially interested in studying the role of the protein matrix in providing for the substrate and reaction specificity for these enzymes. These studies will utilize X-ray crystallographic structure determinations, rapid-reaction kinetics measurements, and site-directed mutagenesis of the enzymes.