Binary Oscillation of Delayed Luminescence: Evidence of the Participation of Qb in the Charge Recombination

Éva Hideg and Sándor Dem eter Institute of Plant Physiology, Biological Research Center, Szeged, P. O. Box 521, Hungary, H-6701 Z. Naturforsch. 40c, 827—831 (1985); received May 23/July 24, 1985 Delayed Luminescence, Oscillation, Oxygen Evolution, Secondary Quinone Acceptor, Chloroplast The flash-induced oscillation of a slowly decaying component of delayed luminescence (half time ~ 42 s) was investigated in spinach chloroplasts for various redox states of the secondary acceptor pool (QB)In preilluminated chloroplasts (30 s light followed by 5 min dark) the slow component exhibited a period-4 oscillation as a function of flash number. Upon oxidation of a major part of the QB pool by dark-adaptation or by ferricyanide treatment of chloroplasts, the period-4 oscillation was converted into a period-2 oscillation, providing direct experimental evi­ dence of the participation of QB in the charge recombination reaction. The measured oscillatory patterns could be simulated in model calculations by assuming that the slow component originates from charge recombination of the redox couples S2Q|