ISOLATION AND MOLECULAR CHARACTERIZATION OF 4 ARGININE GLUTAMATE RICHPOLYPEPTIDES FROM THE SEEDS OF SPONGE GOURD (LUFFA-CYLINDRICA)/

Four arginine/glutamate rich polypeptides referred to as 5k-, 6.5k-, 1 2.5k-, and 14k-AGRPs were purified to homogeneity by gel filtration on Sephadex G-75 followed by CM-cellulose, butyl-Toyopearl 650M, and rev erse-phase HPLC from the seed of sponge gourd (Luffa cylindrica). Tric ine SDS-PAGE indicated that 5k- and 6.5k-AGRPs are single polypeptides , but 12,5k- and 14k-AGRPs consist of two polypeptide chains, which ar e linked by disulfide bond(s), The N-terminal amino acid sequences of four AGRPs were analyzed by a gas-phase sequencer, and the result indi cated that the; are distinct molecules, Comparison of the sequences wi th those of proteins in the protein data base demonstrates that 5k- an d 6.5k-AGRPs have a significant homology with a basic peptide from pum pkin seeds and with cocoa seed vicilin, respectively, and that 12.5k- and 14k-AGRPs are related to 2S seed storage proteins, Furthermore, it was assumed that the four AGRPs might occur in the protein bodies wit hin cells of the seed.