Immobilization of penicillinase on chitosan-modified gold electrodes for enhanced stability and potential biosensing applications

In this research, penicillinase was isolated from <i>Bacillus licheniformis</i> by ammonium sulfate precipitation, dialysis, sephadex-25 chromatography and sodium dodecyl sulfate (SDS)-PAGE. The enzyme was then attached to a chitosan- modified gold (Au) electrode surface via covalent bonds using GA as the linking agent. The immobilized enzyme's characteristics were evaluated by determining various parameters including pH and temperature optima, enzyme activity retention, and reusability potential. The substrate Penicillin G was employed for these assessments. Post-immobilization analysis showed that while the optimal pH range remained constant at 6.5-7.5, the temperature for maximum enzyme activity increased from 34 °C to 38 °C compared to the enzyme in solution. It was found that the immobilized enzyme maintained around 80% of its initial activity after being kept at 4 °C for a period of 30 days. When compared to the enzyme in its free state, the immobilization method made it more stable and usable. Even after 14 consecutive reaction cycles, the immobilized enzyme retained 38% of its initial catalytic activity.