Porcine pancreatic lipase hydrophobically adsorbed on octyl-silica: A robust biocatalyst for syntheses of xylose fatty acid esters

Abstract

This work describes the immobilization of porcine pancreatic lipase (PPL), obtained from crude extract, on silica coated with octyl groups (OS) by interfacial adsorption, a simple and low-cost immobilization protocol. The biocatalyst PPL-OS was employed to the enzymatic preparation of fatty acid esters of d-xylose, a product used especially in the field of cosmetics and pharmacy, especially dermatology, improving the functionality of epidermal cells. The yields of the immobilization in terms of enzymatic activity and protein concentration (98% and 75%, respectively) suggested that PPL present in the crude extract was selectively immobilized on the octyl-silica support, which allowed the hyperactivation of the biocatalyst (recovered activity, 144%), a phenomenon that may be attributed to the interfacial activation of the enzyme on hydrophobic surfaces. The biocatalyst PPL-OS showed to be very robust in organic medium and at high temperature, which is an extremely important characteristic to produce sugar fatty acid esters from the industrial point of view. The syntheses of xylose fatty esters (oleate, caprylate and butyrate) yielded conversions around 70% after short reaction period (2 h) at 60 °C in tert-butyl alcohol. The biocatalyst, even after incubation at 60 °C for 24 h, could be reused in four esterification cycles of 2-h reaction at 60 °C, maintaining 100% of its catalytic activity.