Orbital contributions to CO oxidation in Mo–Cu carbon monoxide dehydrogenase

Abstract

A molecular orbital analysis provides new insight into the mechanism of Mo/Cu carbon monoxide dehydrogenase, and reveals electronic structure contributions to reactivity that are remarkably similar to the structurally related molybdenum hydroxylases. A calculated reaction barrier of ~12 kcal/mol is in excellent agreement with experiment.

CHAPTER 1. Molybdenum and Tungsten-Containing Enzymes: An Overview

“…229,230 although the active site of this enzyme is not mononuclear and its sulfur atom is not terminal (as is the case in other Xo family enzymes), its classification under the Xo family is supported by the considerable sequence and structural homology with the bovine Xo and common reactivity, and also its sensitivity to inhibition by cyanide. ∥∥, [229][230][231][232][233] (1.6) (1.7) a) the history of bovine milk Xo, the prototype enzyme of this family, began more than a century ago, with the schardinger observation (in 1902) of the decolourization (reduction) of methylene blue by formaldehyde in the presence of fresh milk. 234 this was followed by the discovery that milk could also oxidize hypoxanthine and xanthine to urate 235 and the partial purification of Xo in 1924.…”

Scorpionate Complexes as Models for Molybdenum Enzymes

“…These compounds are quite unique and exhibit EPR spectra directly relevant to EPR‐active forms of CODH. Their characterization has provided insights into the electronic structure of CODH and aided the interpretation of enzymatic EPR spectroscopy, which have in turn informed our understanding of the mechanism of CODH . The work in this area is a legacy of Dr. Craig Gourlay, a very talented young chemist who sadly passed away aged 30 (12 July 2012)…”

Functional Studies on Oligotropha carboxidovorans Molybdenum–Copper CO Dehydrogenase Produced in Escherichia coli

“…21 So far, on the basis of the co-crystal structure with inhibitors in addition to computational studies, several reaction mechanisms have been proposed for CO and H2 oxidation. 8,[21][22][23][24][25][26][27][28][29] At the active site, several amino acids were predicted to play a crucial role in the reaction mechanisms of CO and H2 oxidation. The highly conserved glutamate residue Glu763, located in close proximity to the equatorial oxygen ligand at the Mo atom, has been proposed to act as active-site base.…”