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 [Biochemical Journal (1965) 96, 119] or Dawson [FSTA (1971) 3 10J1300] appeared to be homogeneous by these techniques. Total groundnut proteins, extracted in 1M NaBr solution and subjected to double precipitation with 23% (NH4)2SO4, also gave a homogeneous arachin preparation. These 3 homogeneous arachin preparations differed in their rate of hydrolysis by alpha-chymotrypsin, heat coagulation, and dissociation itno subunits. However, sodium dodecyl sulphate and guanidinum hydrochloride denatured them to the same extent, as could be judged by the difference spectra. The P and carbohydrate content of the 3 preparations did not differ significantly.