Photo-accumulation of the P+QB- radical pair state in purple bacterial reaction centres that lack the QA ubiquinone.
FEBS Lett
; 540(1-3): 234-40, 2003 Apr 10.
Article
en En
| MEDLINE
| ID: mdl-12681514
Photo-excitation of membrane-bound Rhodobacter sphaeroides reaction centres containing the mutation Ala M260 to Trp (AM260W) resulted in the accumulation of a radical pair state involving the photo-oxidised primary electron donor (P). This state had a lifetime of hundreds of milliseconds and its formation was inhibited by stigmatellin. The absence of the Q(A) ubiquinone in the AM260W reaction centre suggests that this long-lived radical pair state is P(+)Q(B)(-), although the exact reduction/protonation state of the Q(B) quinone remains to be confirmed. The blockage of active branch (A-branch) electron transfer by the AM260W mutation implies that this P(+)Q(B)(-) state is formed by electron transfer along the so-called inactive branch (B-branch) of reaction centre cofactors. We discuss how further mutations may affect the yield of the P(+)Q(B)(-) state, including a double alanine mutation (EL212A/DL213A) that probably has a direct effect on the efficiency of the low yield electron transfer step from the anion of the B-branch bacteriopheophytin (H(B)(-)) to the Q(B) ubiquinone.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Rhodobacter sphaeroides
/
Ubiquinona
/
Proteínas del Complejo del Centro de Reacción Fotosintética
Idioma:
En
Revista:
FEBS Lett
Año:
2003
Tipo del documento:
Article
Pais de publicación:
Reino Unido