Site-site interaction on mitochondrial F1-ATPase. Functional symmetry of the high-affinity nucleotide binding sites.
Interactions between the high affinity binding sites on mitochondrial F1 were analysed by combined use of the nucleotide analogues 3'-O-(1-naphthoyl)-ADP (N-ADP) and 2'-3'-O-(2,4,6-trinitrophenyl)-ADP (TNP-ADP). The binding behaviour of F1 with respect to these ligands was studied by measuring the fluorescence of F1 and of TNP-ADP and the fluorescence anisotropy of N-ADP. A total of 3 high affinity binding sites can be occupied by TNP-ADP. By exchange experiments, it could be shown that binding of TNP-ADP to such a site considerably accelerates the dissociation of a ligand bound to a neighbouring site. These results support the notion that the functional behaviour of F1 is symmetric: during the catalytic cycle any individual site can successively assume different affinity states as has been predicted by hypotheses such as the binding change model.
D000818:Animals; D001665:Binding Sites; D002417:Cattle; D002846:Chromatography, Affinity; D005454:Fluorescence Polarization; D066298:In Vitro Techniques; D008929:Mitochondria, Heart / Q000201:enzymology*; D009711:Nucleotides / Q000378:metabolism*; D006180:Proton-Translocating ATPases / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics
D009711:Nucleotides; D006180:Proton-Translocating ATPases