Abstract:Three major components of salt-soluble proteins in peanut seeds were roughly purified on Sephadex G-100 gel filtration. Five purified polypeptides, 60.5, 41, 38.5, 18 and 17.5 kDa polypeptides, were harvested with high purity and productivity. Amino acid composition of the three major components (arachin, conarachin I and conarachin II) and the five purified polypeptides were analyzed. It was shown that 17 amino acids, including 7 essential amino acids, were detectable. The contents of asparatic acid, were detectable．The contents of asparatic acid, glutamic acid and arginine were high，whereas methionine and cysteine were extremely low．The methionine levels of three major components in methionine-rich cultivar Shanyou 523 were obviously higher than those in cultivar Haihua 1 The methionine level of conarachin II in three major components was the highest in the two cultivars．Results showed that highest methionine in 17.5 kDa polypeptide was observed in the five purified polypeptides．Western blot showed synthetic changes in 17.5 kDa polypeptide during development of peanut seeds．