PMID: 26333053

Authors:

Yamanaka Y, Kato Y, Hashimoto K, Iida K, Nagasawa K, Nakayama H, Dohmae N, Noguchi K, Noguchi T, Yohda M, Odaka M

Title:

Time-Resolved Crystallography of the Reaction Intermediate of Nitrile Hydratase: Revealing a Role for the Cysteinesulfenic Acid Ligand as a Catalytic Nucleophile.

Journal:

Angew Chem Int Ed Engl. 2015 Sep 7;54(37):10763-7. doi: 10.1002/anie.201502731.

Abstract:

The reaction mechanism of nitrile hydratase (NHase) was investigated using time-resolved crystallography of the mutant NHase, in which betaArg56, strictly conserved and hydrogen bonded to the two post-translationally oxidized cysteine ligands, was replaced by lysine, and pivalonitrile was the substrate. The crystal structures of the reaction intermediates were determined at high resolution (1.2-1.3 A). In combination with FTIR analyses of NHase following hydration in H2 (18) O, we propose that the metal-coordinated substrate is nucleophilically attacked by the O(SO(-) ) atom of alphaCys114-SO(-) , followed by nucleophilic attack of the S(SO(-) ) atom by a betaArg56-activated water molecule to release the product amide and regenerate alphaCys114-SO(-) .