Chloroplast coupling factor 1: dependence of rotational correlation time on polypeptide composition.

Published

Journal Article

Time-resolved fluorescence depolarization measurements were made on chloroplast coupling factor 1 (CF1) labeled with pyrenylmaleimide. Rotational correlation times were determined for native CF1, for CF1 lacking epsilon and/or delta polypeptides, and for activated enzyme. The rotational correlation time measured is characteristic of the rotation of the entire enzyme. Removal of the delta polypeptide resulted in a 25% smaller rotational correlation time, although the delta polypeptide contributes less than 5% of the mass of CF1. Removal of the epsilon polypeptide was without effect. Simultaneous removal of delta and epsilon polypeptides produced a 30% smaller rotational correlation time. Activation of CF1 ATPase by incubation with dithiothreitol reduced the rotational correlation time by 15% relative to that of the latent enzyme. The rotational correlation time of CF1 with delta and epsilon polypeptides removed is essentially that expected for a spherical molecule, whereas the other forms of the enzyme can be approximated as ellipsoids of revolution; the axial ratio of the latent enzyme is estimated from the rotational correlation time and the intrinsic viscosity. These data indicate that the delta polypeptide significantly alters the shape of the enzyme and that a conformational change accompanies dithiothreitol activation of the enzyme.

Full Text

Duke Authors

Cited Authors

  • Schinkel, JE; Hammes, GG

Published Date

  • July 15, 1986

Published In

Volume / Issue

  • 25 / 14

Start / End Page

  • 4066 - 4071

PubMed ID

  • 2874828

Pubmed Central ID

  • 2874828

International Standard Serial Number (ISSN)

  • 0006-2960

Digital Object Identifier (DOI)

  • 10.1021/bi00362a012

Language

  • eng

Conference Location

  • United States