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.
| Original language | English |
|---|---|
| Pages (from-to) | 218-229 |
| Number of pages | 12 |
| Journal | Journal of Physical Chemistry B |
| Volume | 117 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 10 2013 |
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ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Materials Chemistry
- Surfaces, Coatings and Films
Cite this
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
}
TY - JOUR
T1 - Experimental and computational evidence of metal-O2 activation and rate-limiting proton-coupled electron transfer in a copper amine oxidase
AU - Liu, Yi
AU - Mukherjee, Arnab
AU - Nahumi, Nadav
AU - Ozbil, Mehmet
AU - Brown, Doreen
AU - Angeles-Boza, Alfredo M.
AU - Dooley, David M.
AU - Prabhakar, Rajeev
AU - Roth, Justine P.
PY - 2013/1/10
Y1 - 2013/1/10
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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UR - http://www.scopus.com/inward/citedby.url?scp=84872291605&partnerID=8YFLogxK
U2 - 10.1021/jp3121484
DO - 10.1021/jp3121484
M3 - Article
C2 - 23240607
AN - SCOPUS:84872291605
VL - 117
SP - 218
EP - 229
JO - Journal of Physical Chemistry B Materials
JF - Journal of Physical Chemistry B Materials
SN - 1520-6106
IS - 1
ER -