Influence of N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline modification on proton translocation and membrane potential of reconstituted cytochrome-c oxidase support 'proton slippage'

Journal Article · Sun May 05 04:00:00 EDT 1991 · Journal of Biological Chemistry; (USA)

OSTI ID:5671624

Steverding, D; Kadenbach, B ^[1]

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1. Philipps-Universitaet, Marburg, (West Germany)

Bovine heart cytochrome-c oxidase was reconstituted in liposomes and modified with N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ). EEDQ reacted mainly with subunits II and III and to a lower extent with subunit I, as shown by difference labeling with ({sup 14}C)dicyclohexylcarbodiimide. EEDQ treatment of cytochrome-c oxidase vesicles influenced ferrocytochrome c-induced proton pumping by reducing maximally the H+/e- stoichiometry from 0.84 (control) to 0.24, but had only small effects on respiration, respiratory control ratio, and proton conductivity of the proteoliposomes. By titrating the reaction rate of the control and the modified cytochrome-c oxidase vesicles versus the membrane potential, as measured with a Ph3MeP+ electrode, saturation curves are obtained, which in both cases approach 225 mV. The ratios of electron transport rates of the two proton pumps at various membrane potentials decrease between 160 and 225 mV from about 2.2 to 1, indicating that the nonlinear flow/force relationship of these proton pumps is at least partly due to 'slippage' of proton pumping.

• OSTI ID: 5671624
• Journal Information: Journal of Biological Chemistry; (USA), Journal Name: Journal of Biological Chemistry; (USA) Vol. 266:13; ISSN JBCHA; ISSN 0021-9258
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
AROMATICS
AZAARENES
AZINES
BARYONS
BIOCHEMICAL REACTION KINETICS
BODY
CARBON 14 COMPOUNDS
CARBON COMPOUNDS
CARDIOVASCULAR SYSTEM
CATTLE
CELL CONSTITUENTS
CELL MEMBRANES
CYTOCHROME OXIDASE
DOMESTIC ANIMALS
ELEMENTARY PARTICLES
ENZYMES
FERMIONS
HADRONS
HAEM DEHYDROGENASES
HEART
HETEROCYCLIC COMPOUNDS
IMIDES
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LIPOSOMES
MAMMALS
MEMBRANE TRANSPORT
MEMBRANES
MUSCLES
MYOCARDIUM
NUCLEONS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
OXIDOREDUCTASES
PROTONS
PYRIDINES
QUINOLINES
REACTION KINETICS
RUMINANTS
STOICHIOMETRY
TRACER TECHNIQUES
VERTEBRATES