Purification and characterization of a new chitinase from latex of Ipomoea carnea

Abstract A novel enzyme with endochitinase/lysozyme activity was purified to homogeneity from latex of Ipomoea carnea subsp. fistulosa using latex collection, gum removal, ammonium sulphate precipitation, hydrophobic interaction, and anion exchange chromatography. The enzyme was glycosylated (5–6%) and homogeneous on SDS-PAGE; has a molecular mass of 30.06 kDa (MALDI-TOF) and an isoelectric point of pH 4.6. The enzyme exhibited chitinase activity for hydrolysis of glycol chitin and the chitinolytic activity was significantly inhibited by allosamidin and mercuric chloride. The enzyme is stable in the pH range of 4.0–9.5, 80 °C and the optimal activity was observed at pH 5.5 and 50 °C. The enzyme consists of 8 tryptophan, 14 tyrosine, 6 cysteine residues forming three disulfide bridges and the extinction coefficient was estimated as 21.35 M −1  cm −1 . The polyclonal antibody was raised in rabbit and immunodiffusion suggests that the antigenic determinants are unique. The first 15 N-terminal residues G-E-I-T-I-Y-W-G-Q-N-G-F-E-G-S exhibited high identity to other known plant chitinases. Owing to the economic purification, high yield, unique and extraordinary features, stability and behavior; the enzyme ICChII can be widely employed in agriculture, industry, environmental protection, and in recycling chitinous waste from arthropod shellfish and for chito-oligosaccharide production.