dc.creator Babcock, Gerald T. en_US dc.creator Jean, John M. en_US dc.creator Johnston, Leah N. en_US dc.creator Palmer, Graham en_US dc.creator Woodruff, William H. en_US dc.date.accessioned 2006-06-15T14:56:01Z dc.date.available 2006-06-15T14:56:01Z dc.date.issued 1985 en_US dc.identifier 1985-RH-5 en_US dc.identifier.uri http://hdl.handle.net/1811/12198 dc.description $^{**}$This work performed in part under the auspices of the U.S. Department of Energy. en_US dc.description Author Institution: Department of Chemistry, Michigan State University; Inorganic and Structural Chemistry Group (INC-4), Isotope and Nuclear Chemistry Division, Los Alamos National Laboratory, University of California; Inorganic and Structural Chemistry Group (INC-4), Isotope and Nuclear Chemistry Division, Los Alamos National Laboratory, University of California; Department of Biochemistry, Rice University; Inorganic and Structural Chemistry Group (INC-4), Isotope and Nuclear Chemistry Division, Los Alamos National Laboratory, University of California en_US dc.description.abstract Cytochrome oxidase is responsible for perhaps 90% of the aerobic metabolism on earth. Time resolved resonance Raman spectroscopy has been used to study the reoxidation of the reduced and mixed valence forms of this enzyme by dioxygen. Laser flash photodissociation of CO from the carbonmonoxy complex of the enzyme, after this species had been rapidly mixed with oxygenated buffer, was used to initiate the reaction. The immediate product of the flow-flash reaction of the CO-blocked, fully reduced enzyme has a Raman spectrum which is undistinguishable from that of the reduced enzyme. This intermediate is replaced in the first few microseconds by a photolabile species which has Raman frequencies characteristic of oxygenated heme. This indicates the formation of an oxyhemoglobin-like $O_{2}$ complex of cytochrome $a_{3}$ as the precursor of dioxygen reduction. The $O_{2}$ complex is the major species during the 10--50 us of the reaction but converts subsequently to a series of nonphotolabile intermediates as the oxidation reaction proceeds. The CO photolysis product of the mixed valence enzyme contains cytochrome $a^{3+}$ and cytochrome $a^{2+}_{3}$ in its unligated form. This species reacts with $O_{2}$ to form an oxyhemoglobin-like complex of oxygen with $a^{2+}_{3}$ similar to the one formed in the fully reduced enzyme reaction. In the mixed valence oxidase system, the oxy intermediate is replaced by a nonphotolabile species in which $a_{3}$ is oxidized with $t_{1}$ 200 us. These results demonstrate the feasibility of applying time-resolved vibrational techniques to physiologically important, irreversible electron transfer reactions and, in particular, elucidate some of the transient species in the cytochrome oxidase/$O_{2}$ system. en_US dc.format.extent 184969 bytes dc.format.mimetype image/jpeg dc.language.iso English en_US dc.publisher Ohio State University en_US dc.title TIME-RESOLVED RESONANCE RAMAN SPECTROSCOPY OF TRANSIENT SPECIES FORMED DURING THE OXIDATION OF CYTOCHROME OXIDASE BY $DIOXYGEN^{**}$ en_US dc.type article en_US
﻿