title: Studies on lipid synthesis and degradation in developing soybean cotyledons.
abstract: The metabolic activity of individual lipid classes found in developing soybean cotyledons (Glycine max.) is estimated by determining the degradation rate of the compound under given conditions. Pulse-labeling and dual substrate labeling are used to evaluate this parameter. These studies indicate first order decay kinetics for phosphatidic acid, phosphatidylinositol, phosphatidylcholine, phosphatidylethanolamine, N-acyl-phosphatidylethanolamine, diglyceride, and zero order kinetics for triglyceride in cotyledons var. "Harosoy 63" at 30 days after flowering. Decay coefficients for acyl groups and lipid-glycerol moieties within specific lipid classes from either method are comparable. Half-life (t((1/2))) calculations from the decay coefficients indicate extremely rapid turn-over rates (0.08 to 3.4 hours at 25 C) and suggest similar turnover rates of acyl groups and lipid-glycerol in diglyceride and all phospholipids except N-acylphosphatidylethanolamine where acyl groups are replaced independent of the glycerol moiety. These experiments reveal not only different metabolic activity between lipid components of soybean cotyledons, but also describe a new method for measuring lipid turnover in plants.
authors: United States Department of Agriculture, Agricultural Research Service, Department of Agronomy, University of Illinois at Urbana, Champaign, Illinois 61801.
authors: R F
authors: RF
authors: Wilson
authors: R W
authors: RW
authors: Rinne