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Investigation into the source of electron transfer asymmetry in bacterial reaction centers.
- Source :
-
Biochemistry [Biochemistry] 1991 Aug 27; Vol. 30 (34), pp. 8315-22. - Publication Year :
- 1991
-
Abstract
- We have investigated the primary photochemistry of two symmetry-related mutants of Rhodobacter sphaeroides in which the histidine residues associated with the central Mg2+ ions of the two bacteriochlorophylls of the dimeric primary electron donor (His-L173 and His-M202) have been changed to leucine, affording bacteriochlorophyll (BChl)/bacteriopheophytin (BPh) heterodimers. Reaction centers (RCs) from the two mutants, (L)H173L and (M)H202L, have remarkably similar spectral and kinetic properties, although they are quite different from those of wild-type RCs. In both mutants, as in wild-type RCs, electron transfer to BPhL and not to BPhM is observed. These results suggest that asymmetry in the charge distribution of the excited BChl dimer (P*) in wild-type RCs (due to differing contributions of the two opposing intradimer charge-transfer states) contributes only modestly to the directionality of electron transfer. The results also suggest that differential orbital overlap of the two BChls of P with the chromophores on the L and M polypeptides does not contribute substantially to preferential electron transfer to BPhL.
Details
- Language :
- English
- ISSN :
- 0006-2960
- Volume :
- 30
- Issue :
- 34
- Database :
- MEDLINE
- Journal :
- Biochemistry
- Publication Type :
- Academic Journal
- Accession number :
- 1883819
- Full Text :
- https://doi.org/10.1021/bi00098a006