Immobilization of Penaeus vanamei protease on carbon nanotubes and investigation of its activity and stability

Aquatic industrial waste is rich in protein and the best way to reach this organic material is using a protease enzyme. Therefore, the selection of a resistant protease from an aquatic species and using a suitable substrate for immobilization is very importatnt. In this study, the purified protease from shrimp Penaeus vanamei was immobilized on multi-walled carbon nanotubes (MWCNTs). After activating MWCNTs with nitric acid, in ordet to binding of enzyme to MWCNTs, enzyme solution with concentration of 7mg/mL was added to MWCNTs and incubated at 10°C for 4 hours. After three washing with phosphate buffer (pH 7.5), the nano-enzyme was dissolved in 1mL of phosphate buffer. Based on the results, the enzyme immobilizations on the MWCNTs enhance significantly the stability to temperature and extreme pH values. The optimum temperature of immobilized enzyme increased from 60 to 80°C and optimum pH did not change. The kinetic indexes of the enzyme (Km and kcat) changed during the immobilization. These results indicate that immobilized Penaeus vanamei protease on MWCNTs could be used for biotechnological applications due to the high stability.