PURIFICATION AND CHARACTERIZATION OF 2 CHITINASES FROM THE LEAVES OF POKEWEED (PHYTOLACCA-AMERICANA)

Two chitinases, designated PLC-A and PLC-B, were purified from the lea ves of pokeweed (Phytolacca americana) using DEAE-cellulose column chr omatography followed by gel filtration on Sephadex G-75, hydrophobic c olumn chromatography, and ion-exchange FPLC., PLC-A and PLC-B are acid ic and basic proteins having molecular masses of 25 and 29 kDa, and is oelectric points of 3.7 and 9.5, respectively, On the basis of their p artial amino acid sequences, it was seen that PLC-A and PLC-B belong t o class II and class III chitinases, respectively, The optimal pH of P LC-A toward glycolchitin is pH 4.5 and hydrolyzed (GlcNAc)(4) into 2(G lcNAc)(2), and (GlcNAc)(5-6) into (GlcNAc)(2) and (GlcNAc)(3). On the other hand, PLC-B has two optimal pi-Is at 3 and 7 toward glycolchitin and hydrolyzed (GlcNAc)(5) into GlcNAc and (GlcNAc)(4), and (GlcNAc)( 6) into GlcNAc, (GlcNAc)(2), and (GlcNAc)(4).