Crystal structure of cobalt-containing nitrile hydratase

The crystal structure of cobalt-containing nitrile hydratase from Pseudonoc ardia thermophila JCM 3095 at 1.8 Angstrom resolution revealed the structur e of the non-corrin cobalt at the catalytic center. Two cysteine residues ( alpha Cys(111) and alpha Cys(113)) coordinated to the cobalt were posttrans lationally modified to cysteine-sulfinic acid and to cysteine-sulfenic acid , respectively, like in iron-containing nitrile hydratase. A tryptophan res idue (beta Trp(72)), which may be involved in substrate binding, replaced t he tyrosine residue of iron-containing nitrile hydratase. The difference se ems to be responsible for the preference for aromatic nitriles rather than aliphatic ones of cobalt-containing nitrile hydratase. (C) 2001 Academic Pr ess.