ABSTRACT
OBJECTIVE: To chemically modify superoxide dismutase (SOD) with 6-O-quaternized chitosan. METHODS: 2, 3- Epoxypropyl trimethyl ammonium chloride was grafted to reactive C6-OH of chitosan to obtain O-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride (O-HTCC). O-HTCC was covalently coupled to SOD via EDC/NHS-mediated reaction, followed by purification on DEAE Sepharose fast flow column. The conjugates were analyzed by SDS-PAGE, HPLC, and circular dichroism. The enzyme activity of the conjugates was determined using pyrogallol autoxidation assay. RESULTS: SOD was successfully modified by O-HTCC at an efficiency of 90%. The homogeneous conjugates showed similar secondary structure and retained 81.1% of enzyme activity compared with native SOD. CONCLUSION: SOD can be efficiently modified by O-HTCC to prepare O-HTCC-SOD conjugates with high activity retention rate.