Chemical modification of the beta-subunit isolated from a membrane-bound Fo-F1-ATP synthase: modification by 4-chloro-7-nitrobenzofurazan does not inhibit restoration of ATP synthesis or hydrolysis
Khananshvili, D.; Gromet-Elhanan, Z.
Biochemical and Biophysical Research Communications 108(2): 881-887
1982
ISSN/ISBN: 0006-291X PMID: 6184056 Document Number: 195008
The purified, reconstitutively active, .beta.-subunit of the Fo-F1-ATP synthase of Rhodospirillum rubrum chromatophores bound 4-chloro-7-nitrobenzofurazan (NBD-Cl) and dicyclohexylcarbodiimide (DCCD). The binding stoichiometry at saturation was 1 mol of either reagent/mol of .beta. The NBD-modified .beta.-subunit rebound to the .beta.-less chromatophores and restored all their lost ATP-linked activities as efficiently as the untreated .beta., whereas the DCCD-modified .beta.-subunit lost completely its capacity to rebind to the depleted chromatophores. Apparently, the amino acid residue which is modified by NBD-Cl in the isolated .beta.-subunit is not essential for binding, and perhaps, also not for activity.