Metastable radical state, nonreactive with oxygen, is inherent to catalysis by respiratory and photosynthetic cytochromes bc1/b6f.
Proc Natl Acad Sci U S A
; 114(6): 1323-1328, 2017 02 07.
Article
em En
| MEDLINE
| ID: mdl-28115711
ABSTRACT
Oxygenic respiration and photosynthesis based on quinone redox reactions face a danger of wasteful energy dissipation by diversion of the productive electron transfer pathway through the generation of reactive oxygen species (ROS). Nevertheless, the widespread quinone oxido-reductases from the cytochrome bc family limit the amounts of released ROS to a low, perhaps just signaling, level through an as-yet-unknown mechanism. Here, we propose that a metastable radical state, nonreactive with oxygen, safely holds electrons at a local energetic minimum during the oxidation of plastohydroquinone catalyzed by the chloroplast cytochrome b6f This intermediate state is formed by interaction of a radical with a metal cofactor of a catalytic site. Modulation of its energy level on the energy landscape in photosynthetic vs. respiratory enzymes provides a possible mechanism to adjust electron transfer rates for efficient catalysis under different oxygen tensions.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Complexo III da Cadeia de Transporte de Elétrons
/
Complexo Citocromos b6f
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Ano de publicação:
2017
Tipo de documento:
Article
País de afiliação:
Polônia