Identification of an exchangeable non-catalytic site on mitochondrial F1-ATPase which is involved in the negative cooperativity of ATP hydrolysis
| Autor: | Aloysius F. Hartog, Jan A. Berden, C.M. Edel |
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| Rok vydání: | 1993 |
| Předmět: |
Azides
ATPase Biophysics Regulatory site Cooperativity Biochemistry Catalysis Mitochondria Heart Adenosine Triphosphate ATP hydrolysis Animals Nucleotide chemistry.chemical_classification biology Chemistry Hydrolysis Cooperative binding Affinity Labels Cell Biology Ligand (biochemistry) Adenosine Diphosphate Kinetics Proton-Translocating ATPases Enzyme biology.protein Cattle |
| Zdroj: | Biochimica et biophysica acta. 1142(3) |
| ISSN: | 0006-3002 |
| Popis: | Labeling of mitochondrial F1-ATPase with 8-azido-ATP or 8-azido-ADP under turnover conditions with Mg(2+)-ATP resulted in the identification of one exchangeable non-catalytic site whose occupation with a ligand does not influence the ATPase activity of F1 when measured at Vmax. With 8-azido-ADP two exchangeable non-catalytic sites could be labeled, but at one of them the bound ligand exchanges, at least partly, during the illumination under turnover conditions. After labeling an exchangeable non-catalytic site under turnover conditions with 8-azido-ATP or with 8-azido-ADP, F1-ATPase kept the ability to bind NAP3-2N3ADP at the slowly exchangeable noncatalytic site, thereby inhibiting the ATPase activity by 45%, as recently described (Edel et al. (1992) Biochim. Biophys. Acta 1101, 329-338). Covalent modification of the low-affinity non-catalytic site with 8-nitreno-AT(D)P increased the Km of ATP and abolished the negative cooperativity of ATP hydrolysis. This site can therefore be marked as a regulatory site, whose occupation with a nucleotide decreases the affinity of the catalytic sites for ATP. |
| Databáze: | OpenAIRE |
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