Dinitrogen reduction is essential for maintenance of the nitrogen cycle by replenishing ammonia lost through microbial denitrifiction Nitrogenase is a prototypic example of an enzyme with varied Fe:S chemistry associated with electron transfer and substrate reduction. In addition, it is an excellent model of energy transduction with ATP hydrolysis. The Fe-protein of nitrogenase is the obligate ATPase dependent electron transfer agent for substrate reduction. To study how Fe-protein functions in this role, the following questions will be investigated in the next grant period. 1. How is the 4Fe:4S cluster assembled in the FE- protein and how is the resultant cluster processed to the active state? 2. Where are the ATP/ADP binding sites in the Fe- protein? What are the different modes of nucleotide binding and how do they elicit the various structural-conformational changes in the protein?
