A Comparison of the Effects of Metabolic Inhibitors on Chloride Uptake and Photosynthesis In Chara Oorallina

Abstract

A comparative study has been made of the effects of four metabolic inhibitors on chloride uptake and photosynthetic 14C02 fixation by cells of O. corallina, and on oxygen evolution by chloropl<1sts isolated from the cells. Low concentrations of phlorizin and Dio-9 inhibited chloride uptake, but this was not accompanied by an inhibition of photosynthesis in vivo, and could not be correlated with the measured inhibition of electron flow in vitro. Low concentrations of imidazole stimulated the chloride influx in light, but there was again no effect on photosynthetic 14C02 fixation, although imidazole did uncouple electron flow in vitro. The effect of imidazole was dependent on the pH of the external solution. Increasing concentrations of carbonyl cyanide m-chlorophenylhydrazone progressively reduced the chloride influx and 14C02 fixation, and uncoupled electron flow in vitro. The work provides no evidence to support the view that chloride uptake is directly linked to electron flow rather than phosphorylation.