Fatty Acid Synthesis in Hydrilla Chloroplasts

Abstract

AbstractThe rates of carboxylation, photophosphorylation and acetate incorporation have been compared in the intact and broken chloroplasts of Hydrilla verticillata Royle leaves in the presence and absence of certain inhibitors and metabolites. The intact chloroplasts showed low rates of photophosphorylation, high rates of carboxylation, and exhibited normal capacity for fatty acid biosynthesis. In broken chloroplasts a drastic decrease was observed in the rates of carboxylation and acetate incorporation. However, the rate of photophosphorylation was considerably increased. In the presence of light, inhibitors such as iodoacetamide, arsenite and sodium azide decreased the photophosphorylation rate. F‐1,6‐di‐P and PGA stimulated CO2 fixation rate. In the absence of artificial light, inhibitors such as sodium arsenite, gluconate‐6‐phosphate, sodium azide and iodoacetamide decreased the rate of CO2 fixation. CoA, ATP, G‐6‐P, F‐1,6‐di‐P Stimulated the synthesis of fatty acids. Exogenous supply of ADP. NADH, NADP and NADPH did not stimulate fatty acid biosynthesis probably because these compounds could not gain entry into the chloroplasts. Light was necessary for the in vitro fatty acid biosynthesis.