[Isolation and characterization of main albumin fractions of seeds from sunflower (Helianthus annuus L.) and rape (Brassica napus L.)].

The main fractions of the albumins from sunflower and rapeseeds (isolated by means of precipitation with ammonium sulphate or tannin + caffeine and subsequent gel chromatography) are low-molecular, very basic proteins. Their molecular weights range from 10 000 to 16 000, and their isoelectric points (determined by isoelectric focusing and free electrophoresis) are situated at pH greater than 10.0. From the circular dichroism in the wavelength range from 200 to 240 nm it is deduced that the main fraction of the rape albumin is a well-structured protein with 40-46% alpha-helix in aqueous and salt-containing solutions. Denaturation by heating is achieved only at temperatures about 100 degrees C and pH values greater than 9. 20% alpha-helix are left after the action of 8 M urea. This conformational stability is explained by the presence of disulphide linkages in the molecule.