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Issue 39, 2017
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Xanthine oxidase–product complexes probe the importance of substrate/product orientation along the reaction coordinate

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Abstract

A combination of reaction coordinate computations, resonance Raman spectroscopy, spectroscopic computations, and hydrogen bonding investigations have been used to understand the importance of substrate orientation along the xanthine oxidase reaction coordinate. Specifically, 4-thiolumazine and 2,4-dithiolumazine have been used as reducing substrates for xanthine oxidase to form stable enzyme-product charge transfer complexes suitable for spectroscopic study. Laser excitation into the near-infrared molybdenum-to-product charge transfer band produces rR enhancement patterns in the high frequency in-plane stretching region that directly probe the nature of this MLCT transition and provide insight into the effects of electron redistribution along the reaction coordinate between the transition state and the stable enzyme-product intermediate, including the role of the covalent Mo–O–C linkage in facilitating this process. The results clearly show that specific Mo-substrate orientations allow for enhanced electronic coupling and facilitate strong hydrogen bonding interactions with amino acid residues in the substrate binding pocket.

Graphical abstract: Xanthine oxidase–product complexes probe the importance of substrate/product orientation along the reaction coordinate

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Publication details

The article was received on 11 May 2017, accepted on 14 Jun 2017 and first published on 11 Jul 2017


Article type: Paper
DOI: 10.1039/C7DT01728F
Citation: Dalton Trans., 2017,46, 13242-13250
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    Xanthine oxidase–product complexes probe the importance of substrate/product orientation along the reaction coordinate

    J. Yang, C. Dong and M. L. Kirk, Dalton Trans., 2017, 46, 13242
    DOI: 10.1039/C7DT01728F

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