Studies on groundnut proteins. III. Physicochemical properties of arachin prepared by different methods

The homogeneity of arachin prepared by different methods was determined by the techniques of polyacrylamide gel electrophoresis, DEAE-cellulose chromatography, and ultracentrifugation. Arachin obtained by the method of Tombs (Biochem. J.96, 119, 1965) or Dawson (Anal. Biochem.41, 305, 1971) appeared to be homogeneous by these techniques. Total groundnut proteins, extracted in 1 m NaBr solution and subjected to double precipitation with 23% (NH₄)₂SO₄, also gave a homogeneous arachin preparation. These three homogeneous arachin preparations differed in their rate of hydrolysis by alpha-chymotrypsin, heat coagulation, and dissociation into subunits. However, SDS¹ and GuHCl denatured them to the same extent, as could be judged by the difference spectra. The phosphorus and carbohydrate content of the three preparations did not differ significantly.