Stabilization of b-glucuronidase by immobilization in magnetic-silica hybrid supports

Abstract

β-Glucuronidases are a class of enzymes that catalyze the breakdown of complex carbohydrates. They have well documented biocatalytic applications in synthesis, therapeutics, and analytics that could benefit from enzyme immobilization and stabilization. In this work, we have explored a number of immobilization strategies for Patella vulgata β-Glucuronidase that comprised a tailored combination of biomimetic silica (Si) and magnetic nanoparticles (MNPs). The individual effect of each material on the enzyme upon immobilization was first tested. Three different immobilization strategies for covalent attachment on MNPs and different three catalysts for the deposition of Si particles were tested. We produced nine different immobilized preparations and only two of them presented negligible activity. All the preparations were in the micro-sized range (from 1299 ± 52 nm to 2101 ± 67 nm of hydrodynamic diameter). Their values for polydispersity index varied around 0.3, indicating homogeneous populations of particles with low probability of agglomeration. Storage, thermal, and operational stability were superior for the enzyme immobilized in the composite material. At 80◦C different preparations with Si and MNPs retained 40% of their initial activity after 6 h of incubation whereas the soluble enzyme lost 90% of its initial activity within 11 min. Integration of MNPs provided the advantage of reusing the biocatalyst via magnetic separation up to six times with residual activity. The hybrid material produced herein demonstrated its versatility and robustness as a support for β-Glucuronidases immobilization.