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The Active Site Sulfenic Acid Ligand in Nitrile Hydratases Can Function as a Nucleophile
Journal of the American Chemical Society
  • Salette Martinez, Loyola University Chicago
  • Rui Wu, Loyola University Chicago
  • Ruslan Sanishvili, Argonne National Laboratory
  • Dali Liu, Loyola University Chicago
  • Richard C. Holz, Marquette University
Document Type
Format of Original
4 p.
Publication Date
American Chemical Society
Original Item ID
DOI: 10.1021/ja410462j
Nitrile hydratase (NHase) catalyzes the hydration of nitriles to their corresponding commercially valuable amides at ambient temperatures and physiological pH. Several reaction mechanisms have been proposed for NHase enzymes; however, the source of the nucleophile remains a mystery. Boronic acids have been shown to be potent inhibitors of numerous hydrolytic enzymes due to the open shell of boron, which allows it to expand from a trigonal planar (sp2) form to a tetrahedral form (sp3). Therefore, we examined the inhibition of the Co-type NHase from Pseudonocardia thermophila JCM 3095 (PtNHase) by boronic acids via kinetics and X-ray crystallography. Both 1-butaneboronic acid (BuBA) and phenylboronic acid (PBA) function as potent competitive inhibitors of PtNHase. X-ray crystal structures for BuBA and PBA complexed to PtNHase were solved and refined at 1.5, 1.6, and 1.2 Å resolution. The resulting PtNHase–boronic acid complexes represent a “snapshot” of reaction intermediates and implicate the cysteine-sulfenic acid ligand as the catalytic nucleophile, a heretofore unknown role for the αCys113–OH sulfenic acid ligand. Based on these data, a new mechanism of action for the hydration of nitriles by NHase is presented.

Published version. Journal of the American Chemical Society, Vol. 136, No. 4 (January 29, 2014): 1186-1189. DOI. © 2014 American Chemical Society. Used with permission.

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Citation Information
Salette Martinez, Rui Wu, Ruslan Sanishvili, Dali Liu, et al.. "The Active Site Sulfenic Acid Ligand in Nitrile Hydratases Can Function as a Nucleophile" Journal of the American Chemical Society (2014) ISSN: 0002-7863
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