The effect of dipiridamole on recombination kinetics between photooxidizedbacteriochlorophyll and photoreduced primary quinone in reaction centers of purple bacteria

The action of dipyridamole (DIP) on dark recombination between the photooxi dized special pair bacteriochlorophyll BChl(2)(+) and reduced primary quino ne acceptor Q(A)(-) in the reaction centers (RCs) of Rhodobacter sphaeroide s bacteria was studied in the presence of different detergents (LDAO, Trito n X-100, sodium cholate, sodium dodecyl sulfate). DIP acceleratied this rea ction approximately 4-5-fold. In RCs with the extracted H-subunit, the effe ct of DIP was observed at lower concentrations. The possibility of modifica tion of the RC structure-dynamic state by DIP (including changes in RC hydr ogen bonds) is proposed. The modification obviously disturbs the processes of the long-life electrostatic stabilization of Q(A)(-).