초록
The influence of additives on the activity of different covalently and site-specific chemically modified immobilized preparations of a lipase from Geobacillus thermocatenulatus (BTL2) was investigated with a view to obtain a very high active biocatalyst. Non-ionic surfactant and co-solvents at different concentration range were applied. The CNBr-BTL2 immobilized preparation, a very mild immobilized enzyme with similar properties to the soluble enzyme, exhibited an increase in activity of 3 fold in the presence of 20% (v/v) co-solvent (e.g., 1,4-dioxane) and 2.6 fold when Triton X-100 (v/v) was added in the hydrolysis of p-nitrophenylbutyrate. This immobilized preparation was hyper-activated in the presence of both additives although without a synergistic effect. The CNBr-BTL2 modified with polymers showed mild hyperactivation in the presence of each additives and even a synergy in the presence of both. In the best of cases, the HOOC-PEG1500-CNBr-BTL2 preparation showed up to 11 fold higher activity in the presence of additives combination than in absence of them. The glyoxyl-BTL2 preparation was hyper-activated in a similar way than CNBr-BTL2 in the presence of detergents but much less with co-solvents. However, the modified glyoxyl-BTL2 preparations were hyper-activated with solvent (2 fold) but not with detergent. An increase of 3 fold in activity for the modified glyoxyl-BTL2 preparations was observed in the presence of both additives.