Kisker C, Schindelin H, Rees D C
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena 91125, USA.
Annu Rev Biochem. 1997;66:233-67. doi: 10.1146/annurev.biochem.66.1.233.
Molybdenum-containing enzymes catalyze basic metabolic reactions in the nitrogen, sulfur, and carbon cycles. With the exception of the nitrogenase cofactor, molybdenum is incorporated into proteins as the molybdenum cofactor that contains a mononuclear molybdenum atom coordinated to the sulfur atoms of a pterin derivative named molybdopterin. Certain microorganisms can also utilize tungsten in a similar fashion. Molybdenum-cofactor-containing enzymes catalyze the transfer of an oxygen atom, ultimately derived from or incorporated into water, to or from a substrate in a two-electron redox reaction. On the basis of sequence alignments and spectroscopic properties, four families of molybdenum-cofactor-containing enzymes have been identified. The available crystallographic structures for members of these families are discussed within the framework of the active site structure and catalytic mechanisms of molybdenum-cofactor-containing enzymes. Although the function of the molybdopterin ligand has not yet been conclusively established, interactions of this ligand with the coordinated metal are sensitive to the oxidation state, indicating that the molybdopterin may be directly involved in the enzymatic mechanism.
含钼酶催化氮、硫和碳循环中的基本代谢反应。除了固氮酶辅因子外，钼以钼辅因子的形式掺入蛋白质中，该辅因子含有一个单核钼原子，与一种名为钼蝶呤的蝶呤衍生物的硫原子配位。某些微生物也能以类似方式利用钨。含钼辅因子的酶在两电子氧化还原反应中催化一个最终来源于水或并入水中的氧原子与底物之间的转移。基于序列比对和光谱性质，已鉴定出四个含钼辅因子的酶家族。在含钼辅因子的酶的活性位点结构和催化机制框架内讨论了这些家族成员的现有晶体结构。尽管钼蝶呤配体的功能尚未最终确定，但该配体与配位金属的相互作用对氧化态敏感，这表明钼蝶呤可能直接参与酶促机制。
