Characterization of the surface properties of chitosanase under heat stress condition using aqueous two-phase systems and an immobilized-liposome sensor system

The surface properties of chitosanase from Storeptomyces griseus were characterized under heat stress conditions by using aqueous two-phase systems and by using an immobilized-liposome sensor. The surface net (HFS) and local hydrophobicities (LH), were first characterized by using the poly (ethylene glycol) (PEG) / dextran 100-200k (Dex) aqueous two-phase system at various temperatures (25-50°C). The LH values of dithiothreitol (DTT)-treated chitosanase showed a maximum at a specific temperature (45°C) while the HFS values gradually increased with increasing temperature from 40 to 50°C. At the same temperature conditions as above, the surface properties of chitosanase were also analyzed by using a sensor tip immobilized-liposome electrode. Similarly in the case of the variation of LH but not HFS, the detected signal (maxima in electric current) was maximized at 45°C, and a linear correlation between the LH values and the signal values of the new immobilized-liposome sensor system was obtained. It was thus found that the new sensor system was effective for the characterization of the surface properties and LH values, of proteins, as well as the aqueous two-phase system method.