Substrate interactions with nitrogenase: Fe versus Mo.
Biological nitrogen reduction is catalyzed by a complex two-component metalloenzyme called nitrogenase. For the Mo-dependent enzyme, the site of substrate reduction is provided by a [7Fe-9S-Mo-X-homocitrate] metallocluster, where X is proposed to be an N atom. Recent progress with organometallic model compounds, theoretical calculations, and biochemical, kinetic, and biophysical studies on nitrogenase has led to the formulation of two opposing models of where N(2) or alternative substrates might bind during catalysis. One model involves substrate binding to the Mo atom, whereas the other model involves the participation of one or more Fe atoms located in the central region of the metallocluster. Recently gathered evidence that has provided the basis for both models is summarized, and a perspective on future research in resolving this fundamental mechanistic question is presented.
Seefeldt
Lance C
LC
Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84332, USA. seefeldt@cc.usu.edu
Dance
Ian G
IG
Dean
Dennis R
DR
D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism*; D001667:Binding, Competitive; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000378:metabolism; D007501:Iron / Q000737:chemistry* / Q000378:metabolism; D008956:Models, Chemical; D008982:Molybdenum / Q000737:chemistry* / Q000378:metabolism; D008983:Molybdoferredoxin / Q000737:chemistry / Q000378:metabolism; D009591:Nitrogenase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism*; D013379:Substrate Specificity
D001426:Bacterial Proteins; D004791:Enzyme Inhibitors; D008983:Molybdoferredoxin; D008982:Molybdenum; D007501:Iron; D009591:Nitrogenase