Study of the Proton Pumping Mechanism of the Aa3-Type Cytochrome C Oxidase

Cytochrome c oxidase is the last component of the respiratory chains. It accepts electrons from a water-soluble or membrane-anchored cytochrome c and catalyzes the reduction of O2 to water (O2 + 4e- + 4H+ → 2 H2O). In cytochrome aa3 oxidase (C cO), electrons from cytochrome c are first transferred to a copper center, CuA, which is located on the electrically positive (P) side of the membrane, then transferred through low spin heme a to a binuclear center (high spin heme a3 and CuB) which is the catalytic site of the CcOs. O2 binds to reduced heme a3, which is followed by stepwise reduction, requiring four protons and four electrons. These four protons are taken up from the negative (N) side of the membrane through two proton conductive channels (D-channel and K-channel). C cO is also a redox-driven proton pump, i.e., the free energy produced by O2-reduction reaction is coupled to the pumping of four other protons through the proton conductive channel (D-channel) across the membrane. The proton gradient across the membrane can be utilized for other biological activities, for example, ATP synthesis. The molecular mechanism of proton pumping is not well understood.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Biochemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Zhu, Jia-Peng

Contributors dc:contributor

• Gennis, Robert B.

• Chemistry, Biochemistry

Identifier

(UMI)AAI3395565

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/72343