Effect of reduction of the reaction center intermediate upon the picosecond oxidation reaction of the bacteriochlorophyll dimer in Chromatium vinosum and Rhodo Pseudomonas viridis. Academic Article uri icon


  • The photo-oxidation of the reaction center bacteriochlorophyll dimer or special pair was monitored at 1235 nm in Chromatium vinosum and at 1301 nm in Rhodopseudomonas viridis. In both species, the photo-oxidation was apparently complete within 10 ps after light excitation and proceeded unimpeded at low temperatures regardless of the prior state of reduction of the traditional primary electron acceptor, a quinone-iron complex. Thus the requirement for an intermediary electron carrier (I), previously established by picosecond measurements in Rps. sphaeroides (see ref. 4), is clearly a more general phenomenon. The intermediary carrier, which involves bacteriopheophytin, was examined from the standpoint of its role as the direct electron acceptor from the photo-excited reaction center bacteriochlorophyll dimer. To accomplish this, the extent of light induced bacteriochlorophyll dimer oxidation was measured directly by the picosecond response of the infrared bands and indirectly by EPR assay of the triplet/biradical, as a function of the state of reduction of the I/I{minus sign, dot below} couple (measured by EPR) prior to activation. Two independent methods of obtaining I in a stably reduced form were used: chemical equilibrium reduction, and photochemical reduction. In both cases, the results demonstrated that the intermediary carrier, which we designate I, alone governs the capability for reaction center bacteriochlorophyll photooxidation, and as such I appears to be the immediate and sole electron acceptor from the light excited reaction center bacteriochlorophyll dimer. 1977.

published proceedings

  • Biochim Biophys Acta

author list (cited authors)

  • Netzel, T. L., Rentzepis, P. M., Tiede, D. M., Prince, R. C., & Dutton, P. L.

citation count

  • 57

complete list of authors

  • Netzel, TL||Rentzepis, PM||Tiede, DM||Prince, RC||Dutton, PL

publication date

  • June 1977