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 polyacryl-amide gel electrophoresis. In the cotyledons at mid-developing stage a and a′ 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.