The role of lipids and 17‐kDa protein in enhancing the recovery of O₂ evolution in cholate‐treated thylakoid membranes

Abstract

The recovery of O 2 evolution of cholate‐treated thylakoids induced by the simultaneous addition of the 17‐ and 23‐kDa proteins was enhanced by the further addition of thylakoid total lipids up to about 75% of the non‐depleted original broken thylakoids at the optimal concentration of the lipids, through reactivation of electron transfer between the sites of DPC donation and DCIP acceptance. Novel findings clarifing the cause of the discrepancies, with regard to the requirement for the 17‐kDa protein on the O 2 evolution of thylakoid membranes, were also provided, i.e., when the assay of O 2 evolution for the reconstituted systems was carried out at a low level of NaCl (e.g., 0.1 mM), besides the 23‐kDa protein, the 17‐kDa protein was also required for O 2 evolution, however, at a higher level of NaCI (>5 mM) the 17‐kDa protein was not. The results suggest that the 17‐kDa protein takes the place of Cl − or acts as a constituent protecting C − in the Cl − activating sites against fluctuation of the Cl − level in the inner compartment of thylakoid membranes.