Rotation of nucleotide sites is not required for the enzymatic activity of chloroplast coupling factor 1.
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.
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Related Subject Headings
- Structure-Activity Relationship
- Proton-Translocating ATPases
- Plants
- Indicators and Reagents
- Cross-Linking Reagents
- Biochemistry & Molecular Biology
- Binding Sites
- 1101 Medical Biochemistry and Metabolomics
- 0601 Biochemistry and Cell Biology
- 0304 Medicinal and Biomolecular Chemistry
Citation
Published In
DOI
ISSN
Publication Date
Volume
Issue
Start / End Page
Location
Related Subject Headings
- Structure-Activity Relationship
- Proton-Translocating ATPases
- Plants
- Indicators and Reagents
- Cross-Linking Reagents
- Biochemistry & Molecular Biology
- Binding Sites
- 1101 Medical Biochemistry and Metabolomics
- 0601 Biochemistry and Cell Biology
- 0304 Medicinal and Biomolecular Chemistry