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Protein dynamics promote hydride tunnelling in substrate oxidation by aryl-alcohol oxidase

DOI: 10.1039/C7CP05904C DOI Help

Authors: Juan Carro (Centro de Investigaciones Biológicas, CSIC) , Marta Martinez-julvez (University of Zaragoza) , Milagros Medina (University of Zaragoza) , Angel T. Martínez (Centro de Investigaciones Biológicas, CSIC) , Patricia Ferreira (University of Zaragoza)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Chemistry Chemical Physics , VOL 19 , PAGES 28666 - 28675

State: Published (Approved)
Published: October 2017

Abstract: The temperature dependence of hydride transfer from the substrate to the N5 of the FAD cofactor during the reductive half-reaction of Pleurotus eryngii aryl-alcohol oxidase (AAO) is assessed here. Kinetic isotope effects on both the pre-steady state reduction of the enzyme and its steady-state kinetics, with differently deuterated substrates, suggest an environmentally-coupled quantum-mechanical tunnelling process. Moreover, those kinetic data, along with the crystallographic structure of the enzyme in complex with a substrate analogue, indicate that AAO shows a pre-organized active site that would only require the approaching of the hydride donor and acceptor for the tunnelled transfer to take place. Modification of the enzyme's active-site architecture by replacement of Tyr92, a residue establishing hydrophobic interactions with the substrate analogue in the crystal structure, in the Y92F, Y92L and Y92W variants resulted in different temperature dependence patterns that indicated a role of this residue in modulating the transfer reaction.

Subject Areas: Chemistry


Instruments: I24-Microfocus Macromolecular Crystallography