Response of soluble and membrane-bound F1 ATPase of Rhodospirillum rubrum to the photoaffinity label 8-azido ATP.

Soluble ATPase (F1 ATPase) and membrane-bound ATPase (chromatophores) of Rhodospirillum rubrum have been photoaffinity labeled with 8-azidoadenosine 5'-triphosphate (8-N3ATP). The specific binding of 8-N3ATP to nucleotide binding sites of the chromatophore-bound enzyme is established by competition experiments and it is suggested that hydrolysis and phosphorylation involve the same nucleotide binding sites. The experimental results also indicate that the function of the coupling factor F1 is influenced by its environment.