Glycerolipid labelling kinetics in isolated intact chloroplasts

Abstract

Glycerolipid synthesis was studied in intact chloroplasts isolated from three different plant species. The sequential acylation of sn-glycerol 3-phosphate and lysophosphatidate (1-acyl-sn-glycerol 3-phosphate) was confirmed by monitoring the incorporation of oleate synthesized in situ into lysophosphatidate, phosphatidate and diacylglycerol. Lysophosphatidate was not only readily detected in these experiments, but was also present in the chloroplasts at the beginning of the time courses. The rate of glycerolipid synthesis depended primarily on sn-glycerol 3-phosphate supply, and given adequate sn-glycerol 3-phosphate, the proportion of newly synthesized fatty acids diverted into glycerolipids appeared to be determined by differing acyltransferase activities in the chloroplasts isolated from different plant species.