Redox-linked protolytic reactions in soluble cytochrome-c oxidase from beef-heart mitochondria: redox Bohr effects.
Biochim Biophys Acta
; 1318(1-2): 255-65, 1997 Jan 16.
Article
en En
| MEDLINE
| ID: mdl-9030268
ABSTRACT
A study is presented of co-operative redox-linked protolytic reactions (redox Bohr effects) in soluble cytochrome-c oxidase purified from bovine-heart mitochondria. Bohr effects were analyzed by direct measurement, with accurate spectrophotometric and potentiometric methods, of H+ uptake and release by the oxidase associated with reduction and oxidation of hemes a and a3. CuA and CuB in the unliganded and in the CN- or CO-liganded enzyme. The results show that there are in the bovine oxidase four protolytic groups undergoing reversible pK shifts upon oxido-reduction of the electron transfer metals. Two groups with pKox and pKred values around 7 and > 12 respectively appear to be linked to redox transitions of heme a3. One group with pKox and pKred around 6 and 7 is apparently linked to CuB, a fourth one with pKox and pKred of 6 and 9 appears to be linked to heme a. The possible nature of the amino acids involved in the redox Bohr effects and their role in H+ translocation is discussed.
Buscar en Google
Banco de datos:
MEDLINE
Asunto principal:
Complejo IV de Transporte de Electrones
/
Mitocondrias Cardíacas
Límite:
Animals
Idioma:
En
Año:
1997
Tipo del documento:
Article