Isolation of Glycinin-rich Organelles from Developing Soybean Cotyledons

Abstract

Glycinin-rich organelles were isolated from developing soybean cotyledons by two steps of sucrose gradient ultracentrifugation. The organelles had an average density of 1.24, and contained 63-68% protein, 2-14% sugar, and 2-7% lipid. The lipid was 21-24% phospholipid and 76 -79% neutral lipid. The polypeptide compositions of the isolated organelles were compared with those of developing cotyledons and mature protein bodies by sodium dodecyl sulfate polyacrylamide gel electrophoresis. In the cotyledons at mid-developing stage α and α' subunits of β-conglycinin were the major polypeptides, and many other polypeptides including small amount of glycinin were found. In the isolated organelles, most of the component polypeptides were glycinin and a slight amount of β-conglycinin was associated.