Chemical modification and immobilisation of lipase B from Candida antarctica onto mesoporous silicates

The chemical modification and immobilisation of lipase B from Candida antarctica (CalB) onto three different types of mesoporous silicate (MPS) were undertaken. Soluble CalB was modified by two bifunctional reagents, ethylene glycol bis(succinimidyl succinate) (EGNHS) and glutaraldehyde, and by the monofunctional citraconic anhydride. Both chemically modified and untreated enzyme were then immobilised onto SBA-15-, CNS- and MCM-type MPS by adsorption. Thermal stabilities of chemically modified CalB in solution and of the immobilised preparations were evaluated and compared. Citraconic anhydride dramatically reduced the stability of CalB whereas both bifunctionals yielded an eightfold increase in stability over the native free CalB at 70 °C. Following immobilisation of the EGNHS-treated preparation onto CNS-MPS, the stability gain increased to over 60-fold and this combination proved to be the most effective stabilisation strategy. CalB also showed a preference for MPS with larger pores, namely SBA-15. Immobilisation of CalB in alginate beads was also stabilising.