Physiological ligands ADP and Pi modulate the degree of intrinsic coupling in the ATP synthase of the photosynthetic bacterium Rhodobacter capsulatus.
Biochemistry
; 43(34): 11126-34, 2004 Aug 31.
Article
em En
| MEDLINE
| ID: mdl-15323572
The proton-pumping and the ATP hydrolysis activities of the ATP synthase of Rhodobacter capsulatus have been compared as a function of the ADP and P(i) concentrations. The proton pumping was measured either with the transmembrane pH difference probe, 9-amino-6-chloro-2-methoxyacridine, or with the transmembrane electric potential difference probe, bis(3-propyl-5-oxoisoxazol-4-yl)pentamethine oxonol, obtaining consistent results. The comparison indicates that an intrinsic uncoupling of ATP synthase is induced when the concentration of either ligand is decreased. The half-maximal effect was found in the submicromolar range for ADP and at about 70 microM for P(i). It is proposed that a switch from a partially uncoupled state of ATP synthase to the coupled state is induced by the simultaneous binding of ADP and P(i).
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Base de dados:
MEDLINE
Assunto principal:
Fosfatos
/
Fotossíntese
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Difosfato de Adenosina
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Rhodobacter capsulatus
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ATPases de Cloroplastos Translocadoras de Prótons
Idioma:
En
Ano de publicação:
2004
Tipo de documento:
Article