STRUCTURAL STUDIES OF NUCLEOTIDE DEPENDENT ENZYMES

描述：核苷酸在几乎所有的 它们为DNA和RNA提供构建块的生化过程， 在各种代谢途径中充当能量的货币，充当 酶活性的调节剂，起瞬变电子的作用 接受者和捐赠者。这项研究计划的目的是 从分子水平上理解核苷酸在整个生命周期中的作用 乙酰辅酶A羧基酶四种蛋白质体系的催化机理 它是镁(II)-ATP依赖性的，卡那霉素核苷酸转移酶可以 使用ATP、GTP或UTP作为底物，UDP-半乳糖4-差向异构酶 需要紧密结合的NAD和L-苯丙氨酸脱氢酶 其可逆地结合NAD或NADH。 卡那霉素核苷酸转移酶催化各种酶的失活 氨基糖苷类抗生素常用于治疗重症 需氧革兰氏阴性菌感染。UDP-半乳糖4- 差向异构酶在正常的半乳糖代谢中起着关键作用，而且确实是 半乳糖血症是由这种酶的缺陷引起的。乙酰辅酶A 羧基酶催化的第一步，也是绝对关键的一步 长链脂肪酸的生物合成。最后，L-苯丙氨酸 脱氢酶催化L-苯丙氨酸的氧化脱氨。 在拟议的研究中，结合了定点突变、x- 将采用射线结晶学和动力学测量。已被占用 总而言之，这些研究将详细描述 这些蛋白质的酶功能中的核苷酸。

DESCRIPTION: Nucleotides serve important roles in virtually all biochemical processes where they provide building blocks for DNA and RNA, act as currencies of energy in various metabolic pathways, serve as modulators of enzymatic activity, and function as transient electron acceptors and donors. The objective of this research program is to understand, on a molecular level, the role of nucleotides in the overall catalytic mechanisms of four protein systems: acetyl-CoA carboxylase which is Mg(II)-ATP dependent, kanamycin nucleotidyltransferase which can employ ATP, GTP, or UTP as a substrate, UDP-galactose 4-epimerase which requires tightly bound NAD for activity, and L-phenylalanine dehydrogenase which binds NAD or NADH reversibly. Kanamycin nucleotidyltransferase catalyzes the inactivation of various aminoglycoside antibiotics often employed in the treatment of serious infections due to aerobic Gram-negative bacteria. UDP-galactose 4- epimerase plays a key role in proper galactose metabolism, and indeed, one form of galactosemia arises from a deficiency in this enzyme. Acetyl-CoA carboxylase catalyses the first and absolutely critical step in the biosynthesis of long chain fatty acids. Finally, L-phenylalanine dehydrogenase catalyzes the oxidative deamination of L-phenylalanine. For the proposed studies, a combination of site-directed mutagenesis, x- ray crystallography, and kinetic measurements will be employed. Taken together, these studies will provide a detailed description of the role of nucleotides in the enzymatic functions of these proteins.