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Spectroscopic and theoretical studie...

Yoon, Jungjoo.

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Spectroscopic and theoretical studies of oxygen intermediates and catalytic oxygen reduction in the multicopper oxidases.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Spectroscopic and theoretical studies of oxygen intermediates and catalytic oxygen reduction in the multicopper oxidases./
Author:	Yoon, Jungjoo.
Description:	238 p.
Notes:	Adviser: Edward I. Solomon.
Contained By:	Dissertation Abstracts International68-06B.
Subject:	Chemistry, Inorganic. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3267670
ISBN:	9780549064008

Spectroscopic and theoretical studies of oxygen intermediates and catalytic oxygen reduction in the multicopper oxidases.
Yoon, Jungjoo.

Spectroscopic and theoretical studies of oxygen intermediates and catalytic oxygen reduction in the multicopper oxidases. - 238 p.

Adviser: Edward I. Solomon.

Thesis (Ph.D.)--Stanford University, 2007.

The multicopper oxidases (MCOs) catalyze the four-electron reduction of O2 to H2O by utilizing four Cu active centers. Reaction of the fully reduced enzyme with O2 proceeds via sequential two two-electron stages generating the peroxy intermediate (PI) and the native intermediate (NI). In NI, all four Cu sites are oxidized and the three Cu centers in the trinuclear site are mutually bridged by the product of full O2 reduction. A combination of powder/single-crystal EPR, absorption, VT/VTVH MCD spectroscopies and DFT calculations has been applied to relevant model complexes of NI. As a result, fundamental understanding of the unique features of NI has been obtained, which in turn, allowed detailed structural definition of NI. Alternatively, the geometric and electronic structures of PI have been generated using DFT calculations that are calibrated to correspond to the available spectroscopic and kinetic data. Notably, a highly conserved carboxylate residue near the T2 site is shown to have a critical role in stabilizing the PI structure, which induces oxidation of the T2 and one T3 Cu center and strong superexchange stabilization via the peroxide bridge, allowing irreversible binding of O2 at the trinuclear site. Correlation of PI to NI is then made using a two-dimensional potential energy surface generated to describe the catalytic two-electron reduction of peroxide in MCOs. It is found that the reaction is thermodynamically driven by the relative stability of NI and the involvement of the simultaneous two-electron transfer process. Moreover, the low activation barrier (calculated &sim;5--6 kcal/mol and experimental &sim;3--5 kcal/mol) is closely related to the triangular topology of the trinuclear Cu cluster site, as the symmetry provides good donor-acceptor overlap. Finally, it is found that the protonation of the peroxide is not required to drive the O-O bond cleavage reaction at the trinuclear Cu cluster, allowing the MCOs to function over a wide range of pH conditions.

ISBN: 9780549064008Subjects--Topical Terms:

517253
Chemistry, Inorganic.

Spectroscopic and theoretical studies of oxygen intermediates and catalytic oxygen reduction in the multicopper oxidases.
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005 20110830
008 110831s2007 ||||||||||||||||| ||eng d
020 $a 9780549064008
035 $a (UMI)AAI3267670
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040 $a UMI $c UMI
100 1 $a Yoon, Jungjoo. $3 1285785
245 1 0 $a Spectroscopic and theoretical studies of oxygen intermediates and catalytic oxygen reduction in the multicopper oxidases.
300 $a 238 p.
500 $a Adviser: Edward I. Solomon.
500 $a Source: Dissertation Abstracts International, Volume: 68-06, Section: B, page: 3787.
502 $a Thesis (Ph.D.)--Stanford University, 2007.
520 $a The multicopper oxidases (MCOs) catalyze the four-electron reduction of O2 to H2O by utilizing four Cu active centers. Reaction of the fully reduced enzyme with O2 proceeds via sequential two two-electron stages generating the peroxy intermediate (PI) and the native intermediate (NI). In NI, all four Cu sites are oxidized and the three Cu centers in the trinuclear site are mutually bridged by the product of full O2 reduction. A combination of powder/single-crystal EPR, absorption, VT/VTVH MCD spectroscopies and DFT calculations has been applied to relevant model complexes of NI. As a result, fundamental understanding of the unique features of NI has been obtained, which in turn, allowed detailed structural definition of NI. Alternatively, the geometric and electronic structures of PI have been generated using DFT calculations that are calibrated to correspond to the available spectroscopic and kinetic data. Notably, a highly conserved carboxylate residue near the T2 site is shown to have a critical role in stabilizing the PI structure, which induces oxidation of the T2 and one T3 Cu center and strong superexchange stabilization via the peroxide bridge, allowing irreversible binding of O2 at the trinuclear site. Correlation of PI to NI is then made using a two-dimensional potential energy surface generated to describe the catalytic two-electron reduction of peroxide in MCOs. It is found that the reaction is thermodynamically driven by the relative stability of NI and the involvement of the simultaneous two-electron transfer process. Moreover, the low activation barrier (calculated &sim;5--6 kcal/mol and experimental &sim;3--5 kcal/mol) is closely related to the triangular topology of the trinuclear Cu cluster site, as the symmetry provides good donor-acceptor overlap. Finally, it is found that the protonation of the peroxide is not required to drive the O-O bond cleavage reaction at the trinuclear Cu cluster, allowing the MCOs to function over a wide range of pH conditions.
590 $a School code: 0212.
650 4 $a Chemistry, Inorganic. $3 517253
690 $a 0488
710 2 $a Stanford University. $3 754827
773 0 $t Dissertation Abstracts International $g 68-06B.
790 $a 0212
790 1 0 $a Solomon, Edward I., $e advisor
791 $a Ph.D.
792 $a 2007
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3267670