Structural and functional models of nitrile hydratase

摘要

Nitrile hydratase, the enzyme involved in microbial nitrile assimilation, comprises wither one non-heme low-spin iron(Ⅲ) or a non-corrinoid cobalt (Ⅲ) center at the active site. Two carboxamido nitrogens, one cysteine-sulfure, and two sulfurs from a cysteine-sulfenic (Cys-SO) and a cysteine-sulfinic (Cys-SO_2) acid moiety respectively constitute the donor set around the metal center of this hydrolytic enzyme. Binding of one molecule of NO at the sixth site of the iron (Ⅲ) center modulates the activity of the nezyme. It is suggested that a metal-bound hydroxide could be involved in the hydration of nitriles.