Comparative study on the production and immobilization of stem bromelain using polyacrylamide gel matrix and arginine coupled magnetic nanoparticles for enhanced operational stability

Abstract

Protein engineering approaches such as immobilization can be employed to enhance thermal and long-term stability of enzyme. Immobilized bromelain (Brm) has emerged as a critical biocatalyst for optimization in food, textile, cosmetic and pharmaceutical industries. In our study, polyacrylamide, agarose gel matrix and arginine coupled magnetic nanoparticles were synthesized to use as supports for immobilization of stem bromelain. The objective of our study was to compare operational stability of bromelain using various support systems. Our findings showed that the Brm/arg/MNPs had a strong affinity for the substrate, better thermal and pH stability when compared with BrmAG (agarose entrapped Brm) and BrmPG (polyacrylamide entrapped Brm). The rate of reaction was higher for Brm/arg/MNPs (Vmax 23.8 U/ml) than soluble enzyme (7.4 U/ml), BrmAG (Vmax 16.4 U/ml) and BrmPG (Vmax 12.9 U/ml). During storage at 4 °C, BrmAG showed 72% activity while BrmPG retained only 32% activity after 30 days when compared to Brm/arg/MNPs's activity which remained nearly unaffected up to 40 days and it retained its 80% activity for 90 days. For operational stability, Brm/arg/MNPs exhibited 80% of its activity after 15 cycles and only 2% activity loss was observed after 21 cycles. BrmAG and BrmPG retained only 15% and >2% activity after 15 cycles respectively. Our findings showed that arginine coupled magnetic nanoparticles have effectively enhanced the operational and storage stability of bromelain compared to agarose and polyacrylamide gel matrices.