[Purification and characterization of two chitin-binding proteins with lysozyme activity from roots of Raphanus...

A group of chitin-binding proteins were isolated from tuberous roots of Raphanus sativus by affinity chromatography with deaminated regenerated chitin (Fig. 1). SDS-PAGE showed that there are at least five proteins in the sample (Fig. 2-b). Through carboxyl methyl-cellulose chromatography, two chitin-binding proteins with lysozyme activity, named as CBP1 and CBP2 (Fig. 3), were purified to homogeneity with the molecular weights of 26.9 kD and 24.8 kD respectively (Fig. 2-d, e). CBP1 and CBP2 were found to be bifunctional enzymes with activities of lysozyme and chitinase (Figs. 4, 5), but without chitosanase activity (Table 1). The CBP1 and CBP2 could be specifically absorbed by various forms of chitin, such as powdered, regenerated and colloidal forms chitin (Fig. 6). No disulfide bridge was observed in CBP1 and CBP2 by reduced/nonreduced one-dimensional SDS-PAGE (Fig. 7).