2015 年 66 巻 p. 26-30
Nirtogenases are a class of enzymes that catalyze the reduction of N2 to NH3 under ambient conditions in the presence of protons and electrons. The active site of the most prevalent nitrogense is called as the FeMo-cofactor, which is often designated as the M-cluster. It consists of one molybdenum, seven irons, and several sulfur atoms, and represents the most complex metal-sulfur cluster in biology. Some homologues containing vanadium or iron in place of molybdenum exist in alternative nitrogenases, while a precursor of FeMo-cofactor was also identified as an all-iron homologue. Recent crystallographic and biochemical studies on nitrogenases uncovered some important clues about the structurefunction relationship of the nitrogenase active sites, such as the precise structure of the FeMo-cofactor, unique catalytic functions of the FeMo-cofactor and its homologues, and the detailedmechanistic insights in the nitrogen fixation. Transition-metal mediated conversion of small molecules that contain triple bonds has been of interest to the community of coordination chemistry, and this contribution introduces some important progresses in the nitrogenase chemistry/biochemistry made in recent years.