Studies on the Hill reaction of membrane fragments of blue-green algae V. A correlation between the solubilization of a photochemically active chromoprotein (ACP) and the inactivation of photosystem II activity in membrane fragments ofAnabaena cylindrica

摘要

The relationship between a photochemically active chromoprotein (ACP) (cf. ref.1) and photosystem II was investigated with membrane fragments ofAnabaena cylindrica, A. variabilisandP. boryaman.ACP was solubilized from membrane fragments ofA. cylindricabut not from those ofA. variabilisorP. boryanum, when the membrane fragments had been incubated in a dilute buffer and had lost their Hill or photosystem II activity. InA. cylindrica, ACP-solubilization always occurred, independent of photosystem II inactivation, on incubation of the membrane fragments in media without PEG. However, the amount of ACP solubilization accompanying photosystem II inactivation was twice that without photosystem II inactivation. The increase in ACP solubilization accompanying photosystem II inactivation. The kinetics resembled those for the decrease in 695 nm fluorescence emitted by membrane fragments at—196°C (cf.2).The ACP solubilized independent of photosystem II inactivation was assumed to have been released during disruption of intact cells in the preparation of membrane fragments. The slow ACP solubilization upon the inactivation of photosystem II was attributed to the pigment being bound to membranes. We assume that the photo-reactive component of ACP, P690 (cf.3, 4), is released from the membranes during photosystem II inactivation, and that P690 is a component of photosystem II which emits the 695 nm fluorescence at—1