Photoaffinity labeling of soluble chloroplast adenosine 5′-triphosphatase with 3′-O-(4-benzoyl)benzoyl ADP

D. Bar-Zvi, N. Shavit

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


3′-O-(4-benzoyl)benzoyl ADP (BzADP) acts as a reversible inhibitor of the chloroplast coupling factor 1 ATPase (CF1) when incubated with the enzyme in the dark. The Vmax of ATP hydrolysis is decreased and the kinetics of the reaction are altered from noncooperative to cooperative with respect to ATP. Photoactivation of the benzophenone group in BzADP by irradiation with ultraviolet light (366 nm) results in the covalent binding of BzADP to the enzyme and inactivation of its enzymic activity. Polyacrylamide gel electrophoresis of CF1-ATPase in the presence of sodium dodecyl sulfate shows that the analog is bound primarily to the enzyme's β subunit. Complete inactivation of the activated CF1-ATPase occurs upon covalent binding of 2.45 mol BzADP/mol CF1. Binding of BzADP and inactivation of the ATPase are prevented if ADP, but not ATP, is present during the photoactivation step. The presence of Ca2+ during irradiation enhances the rate of BzADP covalent binding as well as the rate of inactivation of the enzyme.

Original languageEnglish
Pages (from-to)340-346
JournalBiochimica et Biophysica Acta - Bioenergetics
Issue number3
StatePublished - 26 Jun 1984


  • Chloroplast ATPase
  • Coupling factor 1
  • Nucleotide binding
  • Photoaffinity labelling

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology


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