Fat Metabolism in Germinating Soybeans. I. Physiology of Native Fat

Abstract

The metabolism of fat in germinating soybeans during periods up to 13 days was studied. Native-fat was prepared by homogenizing cotyledons in sucrose-TRIS-EDTA followed by centrifugation. The native-fat initially contained about 50% water but lost water during the growth period. The water is evidently held either osmotically or by adsorption, since the water content of fat suspended in glucose solutions was inversely proportional to glucose concentration. The dry matter of native-fat initially consisted of about 90% lipids and 10% residual pellet. The latter was mostly protein but traces of nucleic acid were also present. After 10 days of germination, practically all the residual material had been lost. The self-digestion activity of native-fat decreased with successive washings, but the specific activity on triacetin increased. Sonic oscillation destroyed activity on triacetin but enhanced self-digestion. Both self-digestion and activity on triacetin were increased by passing native-fat through a wheat germ lipase solution, indicating adsorption of lipase on the native-fat. Several enzymes other than lipase were shown to be associated with the native-fat.