DEPENDENCE OF CHLOROPHYLL(IDE) SPECTRAL SHIFTS AND PHOTOACTIVE PROTOCHLOROPHYLLIDE REGENERATION AFTER FLASH IN ETIOLATED BARLEY LEAVES

Absorbance spectroscopy at 77 K was used to investigate the effect of temperature on in vivo chlorophyllide shifts and photoactive protochlorophyllide regeneration after a saturating flash, which transformed all protochlorophyllide to chorophyllide. Photoactive protochlorophyllide present in darkness was stable up to 40 degrees C. The rate of Shibata shift and protochlorophyllide regeneration after flash were strongly temperature dependent in the range 0-25 degrees C. At 0 degrees C, the shift was still observed but no regeneration occurred. Only slight effects were observed in the range 25-40 degrees C. At all temperatures, the process of protochlorophyllide regeneration was significantly slower than the Shibata shift. The final chlorophyll shift from 672 to 674 nm was observed up to 40 degrees C. The implication of these results concerning the pigment-protein interactions during the Shibata shift are discussed.