Effect of Conjugation of Activated Glutaraldehyde-Nanochitosan with L-Asparaginase as an Anti Cancer Enzyme on its Stability and Physicochemical Properties

The bacterial Asparaginase is used in the treatment of asparagine-dependent tumors, particularly lymphatic sarcoma and acute lymphoblastic leukemia. However, the instability of the enzyme increases the number of injections that are accompanied by high immune responses. The aim of this study was to investigate the conjugation of L-asparaginase with nanochitosan glutaraldehyde (NCG) derivative and its effect on the physichochemical properties of conjugated enzyme.

In this experimental study, nanochitosan was synthesized using reduction method with acetic acid and its physicochemical properties were evaluated using transmission electron microscopy and particle size analyzer. Activated NCG derivative was produced using 3% acetic acid. The conjugation of NCG derivative to L-asparaginase was performed with different molar ratios of enzyme/nanochitosan (1:2, 1:5, 1:10 and 1:20) in the presence of sodium cyano borohydrate; and the ratio with the highest residual activity was used for physicochemical evaluation. The activity of enzyme at different temperatures and pH, its half-life and stability after freezing and resistance to proteolysis were analyzed through repeated measure analysis of variance using SPSS 18 software.

The results of this study showed that the conjugation of L-asparaginase with NCG derivative resulted in maintaining the 70% enzyme activity. The activity of conjugated enzyme was higher than native enzyme after freezing and trypsin treatment. The optimum pH and temperature of conjugated enzyme did not change, while it had higher activity in wide range of pH and temperature compared with native enzyme.

Conjugation of L-asparaginase with NCG derivative improved physicochemical and stability of enzyme and this method can be used for production of improved L-asparaginase for clinical application.