Binding of the photoreactive ATP analog, 3'-O-(4-benzoyl)benzoyl adenosine 5'-triphosphate (BzATP), to the isolated α and β subunits of TF1 and to the α3β3 'core' complex of the holoenzyme is described. About 1 mol of BzATP/mol of subunit was incorporated to isolated α and β subunits. The incorporation of BzATP was prevented by ATP. Covalent binding of BzATP to the α subunit was in general somewhat lower than that observed with the β subunit. No complex was formed upon mixing of either of the modified subunits with the complementary nontreated subunits. Covalent binding of 3 mol of BzATP/α3β3 complex completely inhibited ATPase activity and resulted in the dissociation of the complex. The labeled nucleotide analog was specifically incorporated into the β subunit of the complex. The holoenzyme TF1, in contrast to the core complex, did not dissociate to the individual subunits upon covalent binding of BzATP. These results are discussed in relation to the location of the catalytic nucleotide binding site(s) and the conformation stability of the α3β3 core complex of TF1.
|Journal||Journal of Biological Chemistry|
|State||Published - 1 Jan 1992|