On seed proteins Part 11. Purification, Chemical Composition, and Some Physico‐chemical Properties of the 11 S Globulin (Helianthinin) in Sunflower Seed

Abstract

Abstract An improved procedure for the isolation and purification of the 11 S globulin from sunflower seeds (helianthinin) is described, including a combined purification by gel chromatography and ionexchange chromatography. The protein has a sedimentation constant of s 20, w = 12.8 x 10 −13 s, a Stokes radius of 57 Å and a diffusion constant of 3.76 x 10 −7 cm 2 s −1 (the last two derived from gel chromatographic analysis). Hence it follows a molecular weight of M s, D = 305000. The isoelectric point determined by isoelectric focusing lies at pH 4.7. High contents of glutamic (26%) and aspartic (14%) acid and arginine (9.7%) as well as a low content of sulphur containing amino acids are characteristic for the amino acid composition. 59% of the acidic amino acids are present in an amidated form. The globulin contains 12 disulphide bridges per molecule.