TRANSPORT & ENZYMOLOGY OF SULFUR AND NITROGEN COMPOUNDS

我们的研究关注的是 无机硫和氮化合物。 重点是ATP 丝状真菌青霉硫酸化酶和APS激酶 产金菌 已将真菌ATP硫酸化酶纯化至均一 并且部分地在动力学、物理和化学上表征。 我们 目前的努力旨在（a）阐明反应机理， (b)鉴定负责功能性氨基酸残基， 酶的完整性，以及（c）探索ATP的潜在相互作用 硫酸化酶与APS激酶。 正在对ATP进行平行研究 来自杜邦青霉（一种嗜热菌）硫酸化酶。 我们的工作与P。 杜邦酶可能会揭示一些因素， 这种酶的热稳定性很好。 APS激酶，第二硫酸盐 活化酶已从产黄青霉中纯化至均一， 正在被定性。 真菌硫酸盐还原途径的研究 将被启动。 其他拟议的项目包括对硝酸盐的研究 还原酶和亚硝酸盐还原酶，特别是来自产黄青霉的亚硝酸盐还原酶， 重点是这些酶的动力学机制。 的一些方法 包括（a）稳态和反应分析 进展动力学，（B）与天然和 化学修饰的酶，和（c）化学修饰的特定的 个氨基酸残基

Our research is concerned with the early steps in the metabolism of inorganic sulfur and nitrogen compounds. Major emphasis is on ATP sulfurylase and APS kinase from the filamentous fungus Penicillium chrysogenum. The fungal ATP sulfurylase has been purified to homogeneity and partially characterized kinetically, physically, and chemically. Our current efforts are aimed at (a) elucidating the mechanism of the reaction, (b) identifying the amino acid residues responsible for the functional integrity of the enzyme, and (c) exploring the potential interaction of ATP sulfurylase with APS kinase. Parallel studies are in progress on the ATP sulfurylase from Penicillium duponti (a thermophile). Our work with the P. duponti enzyme may shed some light on the factors responsible for the remarkable heat stability of this enzyme. APS kinase, the second sulfate activating enzyme has been purified to homogeneity from P. chrysogenum and is being characterized. Studies on the sulfate reduction pathway of fungi will be initiated. Other proposed projects include studies on nitrate reductase and nitrite reductase from P. chrysogenum, with particular emphasis on the kinetic mechanisms of these enzymes. Some of the methods that will be employed include (a) analysis of steady-state and reaction progress kinetics, (b) equilibrium ligand binding with native and chemically modified enzymes, and (c) chemical modification of specific amino acid residues.