Rotational dynamics of chloroplast ATP synthase in phospholipid vesicles.

Published

Journal Article

The rotational dynamics of the purified dicyclohexylcarbodiimide-sensitive H(+)-ATPase (DSA) reconstituted into phospholipid vesicles and of the DSA coreconstituted with the proton pump bacterio-rhodopsin were examined by using the technique of time-resolved phosphorescence emission anisotrophy. The phosphorescent probe erythrosin isothiocyanate was used to covalently label the gamma-polypeptide of DSA before reconstitution. Rotational correlation times were measured under a variety of conditions. The rotational correlation time was independent of the viscosity of the external medium but increased significantly as the microviscosity of the membrane increased. This indicates the rotational correlation times are a measure of the enzyme motion within the membrane. The activation energy associated with the rotational correlation time is 8-10 kcal/mol. At 4 degrees C, the correlation time, typically approximately 100-180 microseconds, was unaffected by the addition of substrates and the presence of a membrane pH gradient. Therefore, molecular rotation of the DSA does not appear to play an important role in enzyme catalysis or ion pumping.

Full Text

Duke Authors

Cited Authors

  • Musier-Forsyth, KM; Hammes, GG

Published Date

  • April 3, 1990

Published In

Volume / Issue

  • 29 / 13

Start / End Page

  • 3236 - 3241

PubMed ID

  • 2159333

Pubmed Central ID

  • 2159333

International Standard Serial Number (ISSN)

  • 0006-2960

Digital Object Identifier (DOI)

  • 10.1021/bi00465a014

Language

  • eng

Conference Location

  • United States