Determination of immobilized lipase stability depends on the substrate and activity determination condition: Stress inactivations and optimal temperature as biocatalysts stability indicators

Lipases A and B from Candida antarctica (CALA and CALB), Thermomyces lanuginosus (TLL) and Candida rugosa have been immobilized on octyl, octyl-vinyl sulfone (blocked with ethylendiamine) and amino-glutaraldehyde. The biocatalysts exhibited different specificity versus triacetin and p-nitro phenyl butyrate. Optimal activities were determined using triacetin for all biocatalysts, and this ranged from 40 degrees C for CALA and TLL, to 60 degrees C for an amino-glutaraldehydeCRL. The biocatalysts were inactivated at 70 and 75 degrees C, determining their residual activities at 25 degrees C or 55 degrees C. The inactivation courses were very different depending on the substrate; in most cases the biocatalysts maintained more activity during the thermal inactivation using triacetin (except using TLL). When determining the residual activities at 55 degrees C, the values increased in most cases, reaching high hyperactivation values using CALA (even 23 folds). That way, the stability of the different preparations was strongly influenced by the substrate and residual activity determination conditions, and did not agree in most cases with the optimal temperatures.

Automated summary

Lipases A and B from Candida antarctica, Thermomyces lanuginosus, and Candida rugosa were immobilized on different carriers and exhibited different specificity and optimal activities. The stability of the preparations was strongly influenced by the substrate and conditions for residual activity determination, not necessarily corresponding to the optimal temperatures.