Effects of long‐chained aliphatic amines on photosynthetic reactions in isolated spinach chloroplasts

Abstract

The effect of six long‐chained aliphatic amines on 14CO2‐reduction, electron transport and the 515 nm absorbance change and shrinkage in isolated intact and broken chloroplasts from spinach (Spinacia oleracea L. cv. Weibulls Medania) was investigated. Five of the six investigated amines affected photosynthesis in intact chloroplasts by inhibiting 14CO2‐reduction. In broken chloroplasts the same amines uncoupled electron transport. When added to intact chloroplasts the five amines induced a light‐dependent oxygen uptake leading to (he formation of hydrogen peroxide. The oxygen uptake was not due to the amines acting as Mehler reactants. The mode of action, different from that of simple aliphatic amines, was an effect on membrane integrity, first affecting the membrane potential. At higher amine concentrations a more general effect on the ion conditions in the thylakoids was evident.