ATP binding at noncatalytic sites of soluble chloroplast F1-ATPase is required for expression of the enzyme activity

Autor:	L L Ehler, Y M Milgrom, Paul D. Boyer
Rok vydání:	1990
Předmět:	biology Chemiosmosis Chemistry ATPase Photophosphorylation Cell Biology Biochemistry chemistry.chemical_compound ATP hydrolysis ATP synthase gamma subunit biology.protein V-ATPase Molecular Biology Adenosine triphosphate ATP synthase alpha/beta subunits
Zdroj:	Journal of Biological Chemistry. 265:18725-18728
ISSN:	0021-9258
DOI:	10.1016/s0021-9258(17)30568-9
Popis:	The F1-ATPase from chloroplasts (CF1) lacks catalytic capacity for ATP hydrolysis if ATP is not bound at noncatalytic sites. CF1 heat activated in the presence of ADP, with less than one ADP and no ATP at non-catalytic sites, shows a pronounced lag in the onset of ATP hydrolysis after exposure to 5-20 microM ATP. The onset of activity correlates well with the binding of ATP at the last two of the three noncatalytic sites. The dependence of activity on the presence of ATP at non-catalytic sites is shown at relatively low or high free Mg2+ concentrations, with or without bicarbonate as an activating anion, and when the binding of ATP at noncatalytic sites is slowed 3-4-fold by sulfate. The latent CF1 activated by dithiothreitol also requires ATP at noncatalytic sites for ATPase activity. A similar requirement by other F1-ATPases and by ATP synthases seems plausible.
Databáze:	OpenAIRE
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