Lecture 8

The Proton Circuit

Current status of the chemiosmotic hypothesis

The redox complexes of the mitochondrial chain

The mitocondrial respiratory chain, the ATP synthase, and the coupled transport processes for phosphorylation of external ADP, shown as a series of proton-pumping activities, with their reaction equations.

Mitochondrial oxidative phosphorylation - the overall reactions and proton pumping stoichiometries of the complexes (for transfer of 2 electrons). The complexes are shown in their physiological state (as dimers for complexes II, III, and IV), and represented by their structures, approximately to scale. The structures for the crystallographically resolved complexes are show by their surfaces, made transparent so as to show the prosthetic groups. The following data sets were used: Complex II, 1fum; Complex III, 1bcc; Complex IV, 2occ; ATP synthase, 1qo1.

View The Rieske iron sulfur protein in a Chime tutorial.

A Table showing membrane proteins for which crystallographic structures are curently available (from Martmut Michel's lab)

The ATP synthase enzyme

Chemiosmotic coupling between electron transport and ATP synthesis

©Copyright 1996, Antony Crofts, University of Illinois at Urbana-Champaign, a-crofts@uiuc.edu