US-France Cooperative Research: Rapid Kinetics of Electron Transfer Reactions of Nitrosomonas

该奖项将支持明尼苏达大学的Alan Hooper博士和蒙彼利埃法国国家健康与医学研究所（INSERM）的Claude Balny博士之间的持续合作研究。本研究旨在了解羟胺氧化还原酶（hydroxylamine oxidoreductase， HAO）的化学功能，该酶是硝化细菌亚硝化单胞菌（Nitrosomonas）在土壤结合氮的有氧氧化过程中所使用的关键酶。在该项目中，研究人员将使用停流技术研究HAO和其他显色电子转移组分的光谱变化。他们将通过比较底物与底物类似物的反应速率和竞争性抑制剂的结合速率来进一步研究活性位点的结构。此外，他们还将研究在HAO和末端氧化酶之间介导的电子载体的种类。胡珀博士是国际公认的细菌硝化专家。巴尔尼博士在一般情况下的止流，特别是在这种酶系统方面的专业知识，使合作的继续是适当的。此外，巴尔尼博士拥有世界上为数不多的可以在高度控制的温度和高静水压力下测量动力学的设施之一。本研究结果将有助于提高对土壤中肥料氨酶氧化的认识。除了生物化学家的基本兴趣之外，这项工作在理解土壤氮循环和通过各种反硝化机制控制土壤氮的农业损失方面具有重要的潜在应用。

This award will support continued collaborative research between Dr. Alan Hooper, University of Minnesota and Dr. Claude Balny, French National Institute for Health and Medical Research (INSERM), Montpellier. This research is aimed at understanding the chemical functioning of hydroxylamine oxidoreductase (HAO), a key enzyme employed by the nitrifying bacterium Nitrosomonas in aerobic oxidation of soil-bound nitrogen. In the proposed project, the investigators will use the techniques of stopped-flow to study spectral changes in HAO and other chromophoric electron transfer components. They will further study the structure of the active site by comparing the rate of reaction of the subtrates with the rate of reaction of subtrate analogs and binding of competitive inhibitors. In addition, they will investigate the kinds of electron carriers mediating between HAO and the terminal oxidase. Dr. Hooper is an internationally recognized expert on bacterial-nitrification. The expertise of Dr. Balny on stopped-flow in general and on this enzyme system in particular makes continuation of the collaboration appropriate. In addition, Dr. Balny has one of the few facilities in the world where kinetics can be measured at highly controlled temperature and high hydrostatic pressures. The results of this research will contribute to increased understanding of enzymic oxidation of fertilizer ammonia in soils. Beyond fundamental interest to biochemists, this work has important potential applications to understanding the soil nitrogen cycle and to control the agricul- tural loss of soil nitrogen through various denitrification mechanisms.