Blue light drives B-side electron transfer in bacterial photosynthetic reaction centers.
Biochemistry
; 40(46): 13767-73, 2001 Nov 20.
Article
em En
| MEDLINE
| ID: mdl-11705365
ABSTRACT
The core of the photosynthetic reaction center from the purple non-sulfur bacterium Rhodobacter sphaeroides is a quasi-symmetric heterodimer, providing two potential pathways for transmembrane electron transfer. Past measurements have demonstrated that only one of the two pathways (the A-side) is used to any significant extent upon excitation with red or near-infrared light. Here, it is shown that excitation with blue light into the Soret band of the reaction center gives rise to electron transfer along the alternate or B-side pathway, resulting in a charge-separated state involving the anion of the B-side bacteriopheophytin. This electron transfer is much faster than normal A-side transfer, apparently occurring within a few hundred femtoseconds. At low temperatures, the B-side charge-separated state is stable for at least 1 ns, but at room temperature, the B-side bacteriopheophytin anion is short-lived, decaying within approximately 15 ps. One possible physiological role for B-side electron transfer is photoprotection, rapidly quenching higher excited states of the reaction center.
Buscar no Google
Base de dados:
MEDLINE
Assunto principal:
Rhodobacter sphaeroides
/
Complexo de Proteínas do Centro de Reação Fotossintética
/
Transferência de Energia
/
Luz
Idioma:
En
Revista:
Biochemistry
Ano de publicação:
2001
Tipo de documento:
Article
País de afiliação:
Estados Unidos