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、藻类和高等植物以无机硫酸盐作为其唯一的硫源，用于生物合成半胱氨酸、蛋氨酸、所有还原型有机含硫辅酶（生物素、硫胺素、辅酶A、硫辛酸等）以及多种结构成分（植物硫脂、硫酸盐等）。 多糖等）。 该研究的总体目标是建立催化真菌无机硫酸盐同化最早步骤的酶的催化机制、调节特性和结构功能关系。 因此，对酶 (a) ATP 硫酸化酶、(b) APS 激酶和 (c)“PAPS 还原酶”的研究按顺序催化：(a) 从 SO42- 和 ATP 形成腺苷-5'-磷酸硫酸盐 (APS)，(b) 从 SO42- 和 ATP 形成 3'-磷酸腺苷-5'-磷酸硫酸盐 (PAPS) APS 和 ATP，以及 (c) PAPS 依赖于 NADPH 和硫氧还蛋白还原成游离或结合的亚硫酸盐。 “PAPS还原酶”实际上是一个多组分系统，从未纯化到动力学特征的均质性。 大多数实验将使用从嗜温真菌青霉中纯化的酶进行。 将对嗜热菌杜邦青霉的酶进行平行研究，目的是确定该生物体蛋白质具有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。