Electron spin echo envelope modulation (ESEEM) spectroscopy of the triplet state of the primary donor of 14N and 15N bacterial photosynthetic reaction centers and of 14N and 15N bacteriochlorophyll a

摘要

An electron spin echo envelope modulation frequency analysis is performed on the triplet state of the primary electron donor (P-860) in 14N reaction centers of the photosynthetic bacterium Rhodopseudomonas sphaeroides R26 and 15N-enriched reaction centers of Rhodopseudomonas sphaeroides 2.4.1, and of the triplet state of 14N or 15N bacteriochlorophyll a in vitro. The hyperfine previous termcouplingnext term constants for 15N 3P-860 are 1.42, 1.74 and 2.04 MHz. The triplet state of the primary donor in bacterial photosynthesis is, on a timescale of a few MHz, delocalized over the two bacteriochlorophyll a molecules making up P-860.