Abstract:Two components of sweet protein were saparated and characterized：mabinlin I (Ma Ⅰ), the major one, with MW of 11600 and isoelectric point pI of 11.8, and mabinlin II(Ma Ⅱ) with MW of 10400 and pI of 11.3. Another component mabinlin Ⅲ(Ma Ⅲ) with MW of 10200 and pI of about 11.8 was found to be produced during the extraction. Ma Ⅱ contains 84 amino acid residues that are fewer 15 amino acid residues than Ma I, of which 6 residues are Pro. These proteins are all single polypeptide chains lacking Ser and Met. 80 amino acid residues are common in Ma I and Ma Ⅱmolecules in which Arg, Glx and Pro are dominant ones. No SH group was detected. After treatment of reductive cleavage with β-mercaptoethanol in 8 M urea, these protein molecules were transformed into dilners and lost the sweet nature.