The thermodynamic H+/ATP ratios of the H+-ATPsynthases from chloroplasts and Escherichia coli.

ABSTRACT: The H(+)/ATP ratio is an important parameter for the energy balance of all cells and for the coupling mechanism between proton transport and ATP synthesis. A straightforward interpretation of rotational catalysis predicts that the H(+)/ATP coincides with the ratio of the c-subunits to beta-subunits, implying that, for the chloroplast and Escherichia coli ATPsynthases, numbers of 4.7 and 3.3 are expected. Here, the energetics described by the chemiosmotic theory was used to determine the H(+)/ATP ratio for the two enzymes. The isolated complexes were reconstituted into liposomes, and parallel measurements were performed under identical conditions. The internal phase of the liposomes was equilibrated with the acidic medium during reconstitution, allowing to measure the internal pH with a gla

SUBMITTER: Steigmiller S 

PROVIDER: S-EPMC2268821 | biostudies-literature | 2008 Mar

REPOSITORIES: biostudies-literature