Self-assembled κ-carrageenase-inorganic hybrid nanoflowers exerting high catalytic efficiency with stable and recyclable properties

kappa-Carrageenan oligosaccharides from kappa-carrageenan hydrolysis are important biochemicals with more bioactivity. Enzyme engineering plays a key role in improving kappa-carrageenase catalytic efficiency for production of kappa-carrageenan oligosaccharides. Effect of metal ions on enzyme activity, especially stability and efficiency, is main factor in catalytic process, but metal ions addition leads to gelation of kappa-carrageenan solution. In this study, molecular dynamics simulation was used to explore the interaction between kappa-carrageenase CgkPZ and Ca2+, and Ca2+ bonded to D164 and E167 in the catalytic center resulting in the catalytic efficiency increase. Circular dichroism analysis indicated that the secondary structure of kappa-carrageenase could change in the presence of Ca2+. Therefore, a novel self-assembly kappa-carrageenase-inorganic hybrid nanoflowers CaNF@CgkPZ was synthesized and systematically characterized. The catalytic efficiency (k(cat)/K-m) of CaNF@CgkPZ was 382.1 mL.mg(-1).s(-1), increased by 292% compared with free x-carrageenase. Notably, the enzyme activity of CaNF@CgkPZ was not reduced significantly after 19 cycles use, and 70-100% relative activity was still retained when stored at 4-25 ? for 15 days. This work provides an efficient approach for kappa-carrageenase immobilization with good storage stability, reusability and enhanced catalytic efficiency, which is of great significance in practical applications.

Automated summary

In this study, a novel self-assembled nanoflower structure CaNF@CgkPZ was synthesized, with significantly improved catalytic efficiency and good stability and reusability.