Cobalt binding in 3QXE

Above is an excerpt from Figure 6C in "Evidence for Participation of Remote Residues...etc by Ondrechen and Ringe which very nicely shows how the cobalt ion is bound into a nitrile hydratase.  There are three sulphur based points of attachment- aC112, aC115 and aC117, the latter two as sulfinic acids and two amide nitrogen points of attachment, aS116 and aC117. It is really clearly shown in this view how the arginine bR52 preorganizes the sulfinic cysteines and amide nitrogens into a planar SSNN arrangement.

The paper that goes with 3QXE

The paper which describes the work that lead to the pdb file 3QXE and its mutant brethren has just been put up as an accepted manuscript for the ACS journal, Biochemistry. Its corresponding authors are Mary Jo Ondrechen and Dagmar Ringe, and it goes by the inviting title of "Evidence for Participation of Remote Residues in the catalytic activity of Co-type Nitrile hydratase from Pseudomonas putida". They have been looking at which residues in the outer shells around the active site influence activity.