ANALYSIS OF THERMOLUMINESCENCE GLOW CURVES OBTAINED FROM DIETHYLPYROCARBONATE-TREATED SPINACH THYLAKOID PREPARATIONS USING THE GENERAL ORDER KINETICS MODEL

The general order kinetics model was applied for the fitting and analy sis of thermoluminescence (TL) glow curves obtained from diethylpyroca rbonate (DEPC)-treated chloroplast samples in order to understand the mechanism of TL dynamics. Incubation of thylakoids for 15 min in the p resence of DEPC resulted in a reduction in the intensity of the B band at around 30 degrees C, with a concomitant enhancement of the Q band at 10 degrees C. This enhanced peak has a value for the order of kinet ics much greater than that of the control peak, indicating that histid ine modification by DEPC at photosystem II (PSII) acceptor sites incre ases the retrapping probability. DEPC also brought about a shift in th e peak temperature of the charged A band from -30 to -15 degrees C. Th e order of kinetics for the shifted peak remained unchanged. Since thi s peak is explained as a DEPC effect on the donor side of PSII, the un changed order of kinetics indicates that retrapping events are not dom inant on the donor side. The mathematical analysis of the TL peaks thu s supports an earlier interpretation and provides further information on the kinetics of retrapping during TL peak formation.