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固氮酶是固氮微生物在常温常压下固氮成氨的催化剂,其催化机理和化学模拟一直是国际上长期致力研究的对象.钼铁蛋白高分辨1.0单晶X射线衍射分析表明,固氮酶催化活性中心铁钼辅基的结构为Mo Fe7S9C(R-homocit),其中,Mo原子和3个u2-硫配体、1个组氨酸和1个高柠檬酸配位,形成八面体构型.高柠檬酸以α-烷氧基氧和α-羧基氧与钼螯合形成双齿配位,氨基酸残基上的组氨酸咪唑氮和半胱氨酸巯基与钼和铁单齿配位.在固氮酶铁钼辅基的生物合成过程中,高柠檬酸和咪唑侧基是在最后的合成步骤插入铁硫碳簇前驱体中,其中高柠檬酸和咪唑侧基有可能对质子传递以及稳定Mo Fe7S9C簇起到重要作用.本文从固氮酶铁钼辅基结构出发,结合最近本课题组从化学模拟出发,将固氮酶催化活性中心铁钼辅基结构修订为加氢新结构Mo Fe7S9C(R-Hhomocit)的研究,着重介绍了近年来国内外固氮酶活性中心、生物合成和催化作用机理的研究进展,并展望了固氮酶的研究前景.
Nitrogenase is a nitrogen-fixing microorganism which can be nitrogen-fixed into ammonia under normal temperature and pressure, and its catalytic mechanism and chemical simulation have been the object of long-term international research.It is indicated by the analysis of high-resolution single crystal X-ray diffraction of molybdenum ferritin that nitrogenase The structure of the active iron-molybdenum prosthetic group is Mo Fe7S9C (R-homocit), in which the Mo atom and three u2-sulfur ligands, one histidine and one high-citric acid coordinate to form an octahedral configuration. High-citric acid chelates with α-alkoxy oxygen and α-carboxy oxygen to form bidentate ligands. Histidine imidazole nitrogen and cysteine thiol groups on amino acid residues coordinate with molybdenum and iron. During biosynthesis of the nitrogenase-bound iron-molybdenum prosthetic group, the hyper-citric acid and imidazole side groups are inserted into the precursor of the iron-sulfur-carbon cluster in the final synthesis step, where high citric acid and imidazole side groups are likely to be proton-transmissive and stable Mo Fe7S9C clusters play an important role.In this paper, starting from the structure of iron-molybdenum-based nitrogenase and combining with the recent work of our group, the structure of the iron-molybdenum-based catalytic activity center of the nitrogenase was revised as Mo Fe7S9C (R -Hhomocit) research, focusing on the introduction of solid at home and abroad in recent years Advances in enzyme active sites, and catalytic mechanism of biosynthesis, and the research prospects nitrogenase enzyme.