Protein dielectric environment modulates the electron-transfer pathway in photosynthetic reaction centers.

ABSTRACT: The replacement of tyrosine by aspartic acid at position M210 in the photosynthetic reaction center of Rhodobacter sphaeroides results in the generation of a fast charge recombination pathway that is not observed in the wild-type. Apparently, the initially formed charge-separated state (cation of the special pair, P, and anion of the A-side bacteriopheophytin, H(A)) can decay rapidly via recombination through the neighboring bacteriochlorophyll (B(A)) soon after formation. The charge-separated state then relaxes over tens of picoseconds and recombination slows to the hundreds-of-picoseconds or nanosecond timescale. This dielectric relaxation results in a time-dependent blue shift of B(A)(-) absorption, which can be monitored using transient absorbance measurements. Protein dynamics also ap

SUBMITTER: Guo Z 

PROVIDER: S-EPMC3491703 | biostudies-literature | 2012 Nov

REPOSITORIES: biostudies-literature