Modulating the catalytic performance of immobilized lipase: Influence of blocking agents and solid-phase physicochemical modifications

This study evaluated how enzyme modifications using polyethyleneimine (PEI) and/or glutaraldehyde (GTA) influence the catalytic behavior of lipase from Thermomyces lanuginosus (TLL) immobilized on hydrophobic Purolite C18. The effect of the blocking agent nature on TLL immobilized on Purolite C18 bearing ethylenediamine-vinyl sulfone groups was also studied. The performance of prepared biocatalysts was compared to the soluble TLL and the commercial immobilized biocatalyst TLL-IM. These immobilization protocols produced biocatalysts with different stability, activity and apparent substrate preference. Although Purolite C18-TLL initially showed lower thermal stability than the biocatalysts immobilized on some heterofunctional supports, PEI coating followed by GTA treatment increased its thermal stability by 9.7-fold, largely surpassing. The catalytic performance of the biocatalysts strongly depended on the performed reaction and utilized substrates. In the hydrolysis of vegetable oils, unmodified Purolite C18-TLL exhibited the highest activity with all assayed oils, after 0.75 h reaching 42% hydrolysis when using coconut oil, whereas the heterofunctional biocatalysts yielded only 3.7-5. In methanolysis, GTA-modified Purolite C18-TLL outperformed the unmodified enzyme, the reaction reaching up to 86.5% yield in 3 h using linseed oil. In esterification reactions involving oleic acid and amyl, isoamyl or octyl alcohols, the reaction catalyzed by Purolite C18-TLL and Purolite C18-TLL-PEI yielded above 85% conversion, while the biocatalysts immobilized on heterofunctional supports showed intermediate performance and the reaction catalyzed by TLL-IM yielded the lowest conversions. Overall, the results demonstrated that immobilization strategies and tailored physicochemical enzyme modifications modulate TLL stability, catalytic activity, and reaction performance.