Electron Transfer and Substrate Reduction in Nitrogenase

.....................................................................................................53 Introduction ................................................................................................54 Materials and Methods ...............................................................................58 Results ........................................................................................................60 Discussion ..................................................................................................68 References ..................................................................................................77 x 4. TEMPERATURE INVARIANCE OF THE NITROGENASE ELECTRON TRANSFER MECHANISM ............................................................................84 Abstract ......................................................................................................84 Introduction ................................................................................................85 Materials and Methods ...............................................................................89 Results and Analysis ..................................................................................92 Discussion ................................................................................................102 References ................................................................................................105 Appendix: Supporting Information ..........................................................110 5. ELECTRON TRANSFER PRECEDES ATP HYDROLYSIS DURING NITROGENASE CATALYSIS.....................................................................123 Abstract ....................................................................................................123 Introduction ..............................................................................................124 Results ......................................................................................................127 Discussion ................................................................................................132 Materials and Methods .............................................................................140 References ................................................................................................144 6. UNCOUPLING NITROGENASE: CATALYTIC REDUCTION OF HYDRAZINE TO AMMONIA BY A MoFe PROTEIN IN THE ABSENCE OF Fe PROTEIN-ATP ...................................................................................149 Abstract ....................................................................................................149 References ................................................................................................157 7. SUMMARY AND FUTURE DIRECTIONS .......................................................159 Conformational Changes in Nitrogenase .................................................160 Electron Transfer Event in Nitrogenase ...................................................169 Kinetic Isotope Effect in the Fe Protein Cycle ........................................174 References ................................................................................................179 APPENDIX ................................................................................................................185...................................................................................................149 References ................................................................................................157 7. SUMMARY AND FUTURE DIRECTIONS .......................................................159 Conformational Changes in Nitrogenase .................................................160 Electron Transfer Event in Nitrogenase ...................................................169 Kinetic Isotope Effect in the Fe Protein Cycle ........................................174 References ................................................................................................179 APPENDIX ................................................................................................................185 CURRICULUM VITAE ............................................................................................189