Enzymology of Inorganic Sulfate Metabolism

无机硫酸盐代谢的酶学

• 批准号: 9105143
• 负责人: Irwin Segel
• 金额: $ 30万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-09-15 至 1995-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9105143&HistoricalAwards=false
• 关键词: Enzymology; Inorganic; Sulfate; Metabolism

Most bacteria, yeasts, fungi, algae, and higher plants use inorganic sulfate as their sole sulfur source for the biosynthesis of cysteine, methionine, all reduced organic sulfur-containing coenzymes (biotin, thiamin, coenzyme A, lipoate, etc.), and a variety of structural components (plant sulfolipid, sulfated polysaccharides, etc.). The overall objective of the research is to establish the catalytic mechanism, regulatory properties, and structure-function relationships of the enzymes which catalyze the earliest steps of inorganic sulfate assimilation by fungi. Thus, a study of the enzymes (a) ATP sulfurylase, (b) APS kinase, and (c) "PAPS reductase" which catalzye, in order, (a) the formation of adenosine-5'- phosphosulfate (APS) from SO42- and ATP, (b) the formation of 3'-phosphoadenosine- 5'- phosphosulfate (PAPS) from APS and ATP, and (c) the NADPH and thioredoxin-dependent reduction of PAPS to free or bound sulfite. "PAPS reductase" is actually a multicomponent system which has never been purified to homogeneity of kinetically characterized. Most of the experiments will be performed with enzymes purified from the mesophilic fungus, Penicillium chrysogenum. Parallel studies will be performed on the enzymes from the thermophile, Penicillium duponti with the objective of identifying the structural features responsible for the remarkable heat stability of proteins from this organism. Enzyme kinetics, equilibrium binding, protein chemistry, and molecular biology methods will be used.

大多数细菌，酵母，真菌，藻类和较高的植物都使用无机硫酸盐作为半胱氨酸，蛋氨酸的生物合成的唯一硫酸盐来源，所有甲基氨酸的生物合成均减少了有机含有硫的有机含有有机硫的共氮酶（生物素，硫胺素，辅酶A，脂肪酸含量和硫酸盐等种植者，以及各种硫酸盐，硫酸含量）。多糖等）。 该研究的总体目的是建立酶的催化机理，调节性质和结构功能关系，从而催化真菌无机硫酸盐同化的最早步骤。 因此，对酶（a）ATP硫酸酶，（b）APS激酶和（c）“ PAPS还原酶”的研究，该酶从SO42-和ATP，（B）从3'-phapsose-5'-磷酸化的形成中构成腺苷-5'-磷酸盐（a），（a）形成腺苷5'-磷酸盐（ap）。 APS和ATP，以及（C）PAPS的NADPH和硫氧还蛋白依赖性减少到游离或结合的硫酸盐。 “ PAPS还原酶”实际上是一个多组分系统，从未被纯化为动力学表征的均匀性。 大多数实验将使用从嗜噬细胞菌群纯化的杀菌的酶进行。 平行研究将对来自嗜热的杜邦（Penicillium duponti）的酶进行，目的是识别负责该生物体蛋白质的显着热稳定性的结构特征。 将使用酶动力学，平衡结合，蛋白质化学和分子生物学方法。