Experimental and computational evidence of metal-O2 activation and rate-limiting proton-coupled electron transfer in a copper amine oxidase

Yi Liu; Arnab Mukherjee; Nadav Nahumi; Mehmet Ozbil; Doreen Brown; Alfredo M. Angeles-Boza; David M. Dooley; Rajeev Prabhakar; Justine P. Roth

doi:10.1021/jp3121484

Experimental and computational evidence of metal-O₂ activation and rate-limiting proton-coupled electron transfer in a copper amine oxidase

Yi Liu, Arnab Mukherjee, Nadav Nahumi, Mehmet Ozbil, Doreen Brown, Alfredo M. Angeles-Boza, David M. Dooley, Rajeev Prabhakar, Justine P. Roth

Chemistry

Research output: Contribution to journal › Article › peer-review

21 Scopus citations

Abstract

The mechanism of O₂ reduction by copper amine oxidase from Arthrobacter globiformus (AGAO) is analyzed in relation to the cobalt-substituted protein. The enzyme utilizes a tyrosine-derived topaquinone cofactor to oxidize primary amines and reduce O₂ to H ₂O₂. Steady-state kinetics indicate that amine-reduced CuAGAO is reoxidized by O₂ >10³ times faster than the CoAGAO analogue. Complementary spectroscopic studies reveal that the difference in the second order rate constant, k_cat/K_M(O₂), arises from the more negative redox potential of Co^III/II in relation to Cu^II/I. Indistinguishable competitive oxygen-18 kinetic isotope effects are observed for the two enzymes and modeled computationally using a calibrated density functional theory method. The results are consistent with a mechanism where an end-on (η¹)-metal bound superoxide is reduced to an η¹-hydroperoxide in the rate-limiting step.

Original language	English (US)
Pages (from-to)	218-229
Number of pages	12
Journal	Journal of Physical Chemistry B
Volume	117
Issue number	1
DOIs	https://doi.org/10.1021/jp3121484
State	Published - Jan 10 2013

ASJC Scopus subject areas

Physical and Theoretical Chemistry
Surfaces, Coatings and Films
Materials Chemistry

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Experimental and computational evidence of metal-O₂ activation and rate-limiting proton-coupled electron transfer in a copper amine oxidase. / Liu, Yi; Mukherjee, Arnab; Nahumi, Nadav; Ozbil, Mehmet; Brown, Doreen; Angeles-Boza, Alfredo M.; Dooley, David M.; Prabhakar, Rajeev; Roth, Justine P.

In: Journal of Physical Chemistry B, Vol. 117, No. 1, 10.01.2013, p. 218-229.

Research output: Contribution to journal › Article › peer-review

Liu, Yi ; Mukherjee, Arnab ; Nahumi, Nadav ; Ozbil, Mehmet ; Brown, Doreen ; Angeles-Boza, Alfredo M. ; Dooley, David M. ; Prabhakar, Rajeev ; Roth, Justine P. / Experimental and computational evidence of metal-O₂ activation and rate-limiting proton-coupled electron transfer in a copper amine oxidase. In: Journal of Physical Chemistry B. 2013 ; Vol. 117, No. 1. pp. 218-229.

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title = "Experimental and computational evidence of metal-O2 activation and rate-limiting proton-coupled electron transfer in a copper amine oxidase",

abstract = "The mechanism of O2 reduction by copper amine oxidase from Arthrobacter globiformus (AGAO) is analyzed in relation to the cobalt-substituted protein. The enzyme utilizes a tyrosine-derived topaquinone cofactor to oxidize primary amines and reduce O2 to H 2O2. Steady-state kinetics indicate that amine-reduced CuAGAO is reoxidized by O2 >103 times faster than the CoAGAO analogue. Complementary spectroscopic studies reveal that the difference in the second order rate constant, kcat/KM(O2), arises from the more negative redox potential of CoIII/II in relation to CuII/I. Indistinguishable competitive oxygen-18 kinetic isotope effects are observed for the two enzymes and modeled computationally using a calibrated density functional theory method. The results are consistent with a mechanism where an end-on (η1)-metal bound superoxide is reduced to an η1-hydroperoxide in the rate-limiting step.",

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AU - Ozbil, Mehmet

AU - Brown, Doreen

AU - Angeles-Boza, Alfredo M.

AU - Dooley, David M.

AU - Prabhakar, Rajeev

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N2 - The mechanism of O2 reduction by copper amine oxidase from Arthrobacter globiformus (AGAO) is analyzed in relation to the cobalt-substituted protein. The enzyme utilizes a tyrosine-derived topaquinone cofactor to oxidize primary amines and reduce O2 to H 2O2. Steady-state kinetics indicate that amine-reduced CuAGAO is reoxidized by O2 >103 times faster than the CoAGAO analogue. Complementary spectroscopic studies reveal that the difference in the second order rate constant, kcat/KM(O2), arises from the more negative redox potential of CoIII/II in relation to CuII/I. Indistinguishable competitive oxygen-18 kinetic isotope effects are observed for the two enzymes and modeled computationally using a calibrated density functional theory method. The results are consistent with a mechanism where an end-on (η1)-metal bound superoxide is reduced to an η1-hydroperoxide in the rate-limiting step.

AB - The mechanism of O2 reduction by copper amine oxidase from Arthrobacter globiformus (AGAO) is analyzed in relation to the cobalt-substituted protein. The enzyme utilizes a tyrosine-derived topaquinone cofactor to oxidize primary amines and reduce O2 to H 2O2. Steady-state kinetics indicate that amine-reduced CuAGAO is reoxidized by O2 >103 times faster than the CoAGAO analogue. Complementary spectroscopic studies reveal that the difference in the second order rate constant, kcat/KM(O2), arises from the more negative redox potential of CoIII/II in relation to CuII/I. Indistinguishable competitive oxygen-18 kinetic isotope effects are observed for the two enzymes and modeled computationally using a calibrated density functional theory method. The results are consistent with a mechanism where an end-on (η1)-metal bound superoxide is reduced to an η1-hydroperoxide in the rate-limiting step.

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