Oxygen evolution and phosphorylation in Scenedesmus as influenced by the inhibitor-β complex from potato and by phloridzin.

Scenedesmus cells were tried as a photosynthesizing test system for the inhibitor-β complex from potato (var. Majestic). The main effect on oxygen evolution is an inhibition of the second gush during the induction period. The formation of bound phosphate is increased by the inhibitor when the cell suspensions are shaken in the light, whereas no significant trend is observed in similar experiments in the dark. - Phloridzin inhibits the same part of oxygen evolution as inhibitor-β from potato when cells pretreated in light are the test object. Concentrations of 1 mM increase the formation of bound phosphate in light, but at 2 mM there is a decrease in this action. Phloridzin and inhibitor-β from potato have different Rf values. - The biochemical effects studied precede possible effects on cell division. - The results are discussed in relation to the localization of the site(s) of action.