EPR studies of the cytochrome-d complex of Escherichia coli.
Biochim Biophys Acta
; 975(1): 175-84, 1989 Jun 23.
Article
em En
| MEDLINE
| ID: mdl-2544229
ABSTRACT
We have examined the thermodynamic and EPR properties of one of the ubiquinol oxidase systems (the cytochrome d complex) of Escherichia coli, and have assigned the EPR-detectable signals to the optically identified cytochromes. The axial high spin g = 6.0 signal has been assigned to cytochrome d based on the physicochemical properties of this signal and those of the optically defined cytochrome d. A rhombic low spin species at gx,y,z = 1.85, 2.3, 2.5 exhibited similar properties but was present at only one-fifth the concentration of the axial high spin species. Both species have an Em7 of 260 mV and follow a -60 mV/pH unit dependence from pH 6 to 10. The rhombic high spin signal with gy,z = 5.5 and 6.3 has been assigned to cytochrome b-595. This component has an Em7 of 136 mV and follows a -30 mV/pH unit dependence from pH 6 to 10. Lastly, the low spin gz = 3.3 signal which titrates with an Em7 of 195 mV and follows a -40 mV/pH unit dependence from pH 6 to 10 has been assigned to cytochrome b-558. Spin quantitation of the high-spin signals indicates that cytochrome d and b-595 are present in approximately equal amounts. These observations are discussed in terms of the stoichiometry of the prosthetic groups and its implications on the mechanism of electron transport.
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01-internacional
Base de dados:
MEDLINE
Assunto principal:
Citocromos
/
Proteínas de Escherichia coli
/
Complexo de Proteínas da Cadeia de Transporte de Elétrons
/
Escherichia coli
Idioma:
En
Revista:
Biochim Biophys Acta
Ano de publicação:
1989
Tipo de documento:
Article