Elucidation of mechanisms for catalytic center maturation and catalysis of nitrile hydratase family enzyme

通过对β Arg 56被Lys取代的铁型腈水合酶（NHase）进行时间分辨X射线晶体学研究，获得了酶-底物复合物的结构。通过替换两个精氨酸残基驻留在活性位点口袋的一个NHase家族酶，硫氰酸盐水解酶（SCNase），我们表明，大小以及表面电荷的底物结合口袋是重要的SCNase的底物特异性。至于成熟机制，我们发现SCN酶激活蛋白P15 K负责催化亚基γ中Cys配体的重折叠、金属插入和翻译后修饰。掺入金属的γ亚基与其他亚基α和β形成复合物，以形成成熟的SCN酶。

By performing time-resolved X-ray crystallography of Fe-type nitrile hydratase(NHase) whoseβArg56 were substituted by Lys, we obtained the structure of the enzyme-substrate complex. By replacing two Arg residues resided in the active site pocket of a NHase family enzyme, thiocyanate hydrolase(SCNase), we showed that the size as well as the surface charge of the substrate binding pocket was important for the substrate specificities of SCNase. As for the maturation mechanism, we found that the SCNase activator protein, P15K, is responsible for the refolding, metal-insertion and post-translational modification of Cys ligand in the catalytic subunit,γ. The metal-incorporatedγsubunit form the complex with the other subunits,αandβ, to form the mature SCNase.