A study of state changes in chlorella: The effect of uncoupler and energy transfer inhibitors

Abstract

Pre-illumination of Chlorella cells at room temperature with light primarily absorbed by PSII(650 nm) produces a state called state II. This is characterized by high fluorescence at 715 nm(high F715/F685) at liquid nitrogen temperature. Alternately if the cells are pre-illuminated by light primarily absorbed by PSI (710 nm) then state I with high fluorescence at 685 nm (low F 715/F685) at 77K is produced. We have investigated the role of photophosphorylation in the development of state I/II in chlorella cells using uncoupler and energy transfer inhibitors. The results suggested that the development of state I depends upon the energization of the membrane. Both DCCD and TPTC which permit build up of proton gradient block the adaptation to state I indicating that proton gradient formation alone is not sufficient to develop state I. The data obtained by us as also published in the literature indicate that redox states of the electron transport carriers are responsible for the development of state I. © 1982, Walter de Gruyter. All rights reserved.