Structures and Functions of the Nitrogenase Proteins

Mechanism of Molybdenum Nitrogenase

“…The conclusions have confirmed or explained many previous results but also have given us a number of surprises. They come primarily from the X-ray crystallographic work of the groups of Rees − ,, and Bolin ,,, and have largely superseded the results from other structural methods like ultracentrifugation and electron microscopy. − Much attention has naturally focused on the nature of the two kinds of metal- and sulfur-containing clusters and their immediate environments. The models of these two clusters are shown in Figures and and are discussed in fine detail in the accompanying paper on nitrogenase studies by Rees.…”

NITROGENASE: A Nucleotide-Dependent Molecular Switch

“…For some time, it has been recognized from the spectroscopic properties of the protein that there are two groups of metal centers: the diamagnetic, EPR-silent P-cluster pairs (or P-cluster or P-center), and the unusual S=3/2 paramagnetic FeMo-cofactor (or M-center or "cofactor"). Although there has been much speculation as to the arrangement and structure of the 2 Mo, 30 Fe, and --34 inorganic S that form these clusters, the recent three-dimensional structures of the protein (14)(15)(16)(17)(18)(19)(20) revealed how truly unique they are. Each of the two FeMo-cofactor units contains 1 Mo:7 Fe:9 S and one homocitrate molecule, and almost certainly provides the site of substrate binding and reduction.…”

“…However, the similarity of the ATP-dependent electron transfer in nitrogenase to many other nucleotide-dependent energy-transducing systems in higher organisms should make this enzyme of general interest to biochemists. The recent solution of three-dimensional structures for both the nitrogenase proteins (13)(14)(15)(16)(17)(18)(19)(20) em1The nomenclature fur the nitrogen fixation enzyme is rich and varied. The molybdenum-iron protein is frequently referred to as MoFe-protein, component 1, or dinitrogenase, while the iron protein is referred to as Fe-protein, component 2, or dinitrogenase reductase.…”

Revisiting mechanistic studies on dinitrogen reduction to ammonia by an iron dinitrogen complex as nitrogenase mimic

“…Although, this transformation facilitates by the Mo‐Fe cofactors of nitrogenase enzymes but how they do so, still in debate due to their exact site of dinitrogen coordination and reduction . Over the years, the exact site of N 2 attachment was known to contain the Mo cofactor of nitrogenase enzyme and was well established by Rees et al In addition, the considerable efforts have been made by Hoffman et al for the Mo‐based mechanism …”