Enzymology of Inorganic Sulfate Metabolism

无机硫酸盐代谢的酶学

• 批准号: 8802731
• 负责人: Irwin Segel
• 金额: $ 25.32万
• 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: 1988
• 资助国家: 美国
• 起止时间: 1988-09-01 至 1992-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8802731&HistoricalAwards=false
• 关键词: Enzymology; Inorganic; Sulfate; Metabolism

Most bacteria, yeast, fungi, algae and higher plants can use inorganic sulfate as their sole source of sulfur for the biosynthesis of cysteine, methionine, and a variety of organic sulfur-containing coenzymes. The objective of this research is to establish the structure-function relationships of the enzymes which catalyze the early steps of sulfate assimilation. The enzymes ATP Sulfurylase, APS kinase, and PAPS reductase will be studied. The first two catalyze the two-step ATP- dependent "activation" of S042- forming 3'- phosphoadenosine- 5' -phosphosulfate (PAPS). The last named enzyme (actually a multicomponent system) catalyzes the NADPH- and thioredoxin- dependent reduction of PAPS to inorganic sulfite. Specific aims include (a) determining the kinetic and chemical mechanisms, (b) identifying aminoacyl residues at the active site, and (c) exploring the potential interaction of the two sulfate activating enzymes to form a "PAPS synthetase" complex. The experiments will be conducted with enzymes purified from the filamentous fungus Penicillium chrysogenum and from spinach leaf. Parallel studies will be performed on the enzymes from P. duponti (a thermophile) with the objective of identifying the structural features responsible for the remarkable heat stability of thermophile enzymes. Enzyme kinetics, protein chemistry, and molecular biology methods will be used. Inorganic sulfate is reduced to a state suitable for incorporation into sulfur containing amino acids and other factors by a complex pathway in plants and microorganizms. The investigator employs a sophisticated mathematical approach to the study of these enzymes. He wishes to analyze the chemical mechanisms by which they carry out the reactions involved.

大多数细菌、酵母、真菌、藻类和高等植物都可以利用 无机硫酸盐作为其唯一的硫源， 生物合成半胱氨酸、蛋氨酸和各种有机 含硫辅酶。 本研究的目的是 建立结构-功能关系 催化硫酸盐同化的早期步骤的酶。 ATP硫酸化酶、APS激酶和PAPS还原酶 将被研究。 前两个催化两步ATP- S 042-形成3 '-磷酸腺苷的依赖性“激活” 5' -磷酸硫酸盐（PAPS）。 最后命名的酶（实际上是一种 多组分系统）催化NADPH-和硫氧还蛋白- PAPS向无机亚硫酸盐的依赖性还原。 具体 目标包括：（a）确定动力学和化学 （B）鉴定活性位点上的氨酰基残基， （c）探讨两者之间的潜在互动关系 硫酸化活化酶以形成“PAPS合成酶”复合物。 实验将用从以下纯化的酶进行： 丝状真菌产黄青霉和菠菜 叶 平行研究将在酶从 杜庞蒂（P. duponti）（一种嗜热菌），目的是鉴定 这种结构特征导致了 嗜热酶的稳定性。 酶动力学，蛋白质 将使用化学和分子生物学方法。 无机硫酸盐被还原到适合于 掺入含硫氨基酸和其他 在植物和微生物中通过复杂的途径影响因子。 的 调查人员采用了一种复杂的数学方法， 对这些酶的研究。 他想分析化学物质 它们进行相关反应的机制。