Rotation of nucleotide sites is not required for the enzymatic activity of chloroplast coupling factor 1.


Journal Article

New heterobifunctional photoaffinity cross-linking reagents, 6-maleimido-N-(4-benzoylphenyl)hexanamide, 12-maleimido-N-(4-benzoylphenyl)dodecanamide, and 12-[14C]maleimido-N-(4-benzoylphenyl)dodecanamide, were synthesized to investigate the mechanism of ATP hydrolysis by chloroplast coupling factor 1. These reagents react with sulfhydryl groups on the gamma-polypeptide. Subsequent photolysis cross-links the gamma-polypeptide covalently to alpha- and beta-polypeptides. The cross-linkers prevent major movements of the gamma-polypeptide with respect to the alpha- and beta-polypeptides but are sufficiently long to permit some flexibility in the enzyme structure. When approximately 50% of the gamma-polypeptide was cross-linked to alpha- and beta-polypeptides, a 7% loss in ATPase activity was observed for the longer cross-linker and a 12% loss for the shorter. These results indicate that large movements of alpha- and beta-polypeptides with respect to the gamma-polypeptide are not essential for catalysis. In particular, rotation of the polypeptide chains to create structurally equivalent sites during catalysis is not a required feature of the enzyme mechanism.

Full Text

Duke Authors

Cited Authors

  • Musier, KM; Hammes, GG

Published Date

  • September 22, 1987

Published In

Volume / Issue

  • 26 / 19

Start / End Page

  • 5982 - 5988

PubMed ID

  • 2891373

Pubmed Central ID

  • 2891373

International Standard Serial Number (ISSN)

  • 0006-2960

Digital Object Identifier (DOI)

  • 10.1021/bi00393a006


  • eng

Conference Location

  • United States