SEDIMENTATION OF CRYSTALLINE GLOBULIN FROM CUCURBIT SEEDS

Abstract

Crystalline globulins from cucurbit seeds decreased in dispersibility in the order: squash and pumpkin, cucumber, watermelon. Analysis by high-speed sedimentation showed that most of the dispersions in buffers below pH 4.8 contained two components, with sedimentation constants approximately 3 and 7. The proportions of the components varied with species, pH, and time after preparation. The globulin from all species was insoluble in dilute buffers between pH 4.8 and 8.2. A third component, with sedimentation constant approximately 12, was dominant above pH 8.2 but was gradually replaced by the "7" component as the pH was increased. The "3" component was found only at pH 11.9. The globulin from each species is considered to be a single protein with the components forming an association–dissociation system.