Biosynthesis of chlorophyll P-680 of photosystem II in greening leaves of plants adapted to heat shock

In etiolated pea and maize leaves illuminated after incubation at 38 degree s C, a new dark reaction was shown manifested in the bathochromic shift of spectral bands and accompanied by esterification of the product of protochl orophyllide photochemical reduction-Chld 684/676: Chld 684/676 --> Chi 688/ 580. After completion of the reaction a rapid (20-30 sec) quenching of the fluorescence of the reaction product (Chl 688/680) was observed. The reacti on Chld 684/676 --> Chi 688/680 is inhibited under anaerobic conditions and in the presence of cyanide; the reaction accompanied by Chi 688/680 fluore scence quenching is not observed in pea mutants with impaired function of p hotosystem II reaction centers. The spectral properties of the formed Chi f orm with the absorption maximum at 680 nm, fluorescence quenching, and simu ltaneous synthesis of pheophytin suggest that the reaction is connected wit h the chlorophyll of photosystem II reaction center-P-680.