固氮酶催化活性中心及其化学模拟

Abstract

Nitrogenase catalyzes the reduction of dinitrogen to ammonia in the process of biological nitrogen fixation. In the past few decades, its catalytic mechanism and chemical simulation have been widely studied. The high resolution X-ray structural analysis of the MoFe protein in nitrogenase reveals the iron molybdenum cofactor (FeMo-co) as a cage structure, MoFe7S9C( R -homocit). The molybdenum atom is coordinated by three sulfur atoms, a nitrogen atom from histidine residue and two oxygen atoms from R -homocitrate. Recently, the model has been modified as a protonated structure of MoFe7S9C( R -Hhomocit). Homocitrate and imidazole sidechain may play important roles in delivering proton and stabilizing the MoFe7S9C cluster in the process of N2 reduction. However the mechanism of N2 reduction remains unclear. In this review, the chemistry of molybdenum with homocitrate and imidazole is discussed, including the iron molybdenum sulfur complexes, which will be helpful to understand the coordination environment of molybdenum atom in iron molybdenum cofactor.