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

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.     

Immobilization of lipase on hydrophobic nano-sized magnetite particles

As a tool for the stable enzyme reuse, enzyme immobilization has been studied for several decades. Surface-modified nano-sized magnetite (S-NSM) particles have been suggested as a support for the immobilization of enzyme in this study. Based on the finding that a lipase is strongly adsorbed onto a hydrophobic surface, NSM particles (8–12 nm) were made hydrophobic by binding of sodium dodecyl sulfate via a sulfate ester bond. Various types of measurements, such as transmission electron microscopy, X-ray diffraction, infrared spectroscopy, vibration sample magnetometer, and thermo gravimetric analysis, were conducted in characterizing S-NSM nanoparticles. S-NSM particles were used for the adsorption of porcine pancreas lipase (PPL). A dodecyl carbon chain is expected to form a spacer between the surface of the NSM and the lipase adsorbed. The immobilized PPL showed the higher specific activity of oil hydrolysis than that of free one. Immobilized PPL could be recovered by magnetic separation, and showed the constant activity during the recycles.     

Improving the catalytic performance of porcine pancreatic lipase in the presence of [MMIm][MeSO4] with the modification of functional ionic liquids

Porcine pancreatic lipase (PPL) was chemically modified with various functional ionic liquids (ILs) to increase its catalytic performance in water-miscible IL. Catalytic activity and thermostability were tested with a p-nitrophenyl palmitate (pNPP) hydrolysis reaction. The native enzyme lost 18% of its initial activity in 0.4 M [MMIm][MeSO₄], whereas the activities of all the modified enzymes increased. The [HOOCBMIm][Cl] modification led to a 2-fold increase in activity in 0.3 M [MMIm][MeSO₄] than in aqueous. All the modified enzymes exhibited higher thermostability compared with the native enzyme at high temperature. In particular, the [HOOCBMIm][Cl] modification led to a 6-fold increase in thermostability at 60 °C. Conformational changes were confirmed by fluorescence spectroscopy and circular dichroism spectroscopy to elucidate the mechanism of catalytic performance alteration.     

Immobilization of Candida rugosa lipase on sporopollenin from Lycopodium clavatum

Sporopollenin is a natural polymer obtained from Lycopodium clavatum, which is highly stable with constant chemical structure and has high resistant capacity to chemical attack. In this study, immobilization of lipase from Candida rugosa (CRL) on sporopollenin by adsorption method is reported for the first time. Besides this, the enzyme adsorption capacity, activity and thermal stability of immobilized enzyme have also been investigated. It has been observed that under the optimum conditions (Spo-E_(0.3)), the specific activity of the immobilized lipase on the sporopollenin by adsorption was 16.3 U/mg protein, which is 0.46 times less than that of the free lipase (35.6 U/mg protein). The pH and temperature of immobilized enzyme were optimized, which were 6.0 and 40 °C respectively. Kinetic parameters V_max and K_m were also determined for the immobilized lipase. It was observed that there is an increase of the K_m value (7.54 mM) and a decrease of the V_max value (145.0 U/mg-protein) comparing with that of the free lipase.     

Immobilization to improve the properties of Pseudomonas fluorescens lipase for the kinetic resolution of 3-aryl-3-hydroxy esters

Lipase AK “Amano” 20 from Pseudomonas fluorescens (PFL) was immobilized using diverse immobilization techniques. The methods developed, especially the optimized sol-gel procedure, enabled the fine tuning of enzymatic activity and enantioselectivity for the kinetic resolution of racemic ethyl 3-aryl-3-hydroxypropanoates. The aryl moieties of the racemates include furan-2 and 3-yl, thiophen-2 and 3-yl, benzofuran-2-yl, benzo[b]thiophen-2-yl, as well as phenyl and 4-chloro- and 4-methoxyphenyl groups. The optimized PFL sol-gel preparation (encapsulation from the aqueous solution of PFL, sucrose and Celite in situ) was shown to be efficiently reusable in ten cycles and highly enantioselective with E > 200 to all other substrates except furan-2 and 3-yl and thiophen-2 and 3-yl substituted compounds with E 108-184.     

Resolution of 2-cyano-2-methylalkanoic acids via porcine pancreatic lipase-catalyzed enantioselective ester hydrolysis: effect of the alcohol moiety of the substrate ester on enantioselectivity

2-Cyano-2-methylalkanoic acids were resolved via porcine pancreatic lipase-catalyzed enantioselective ester hydrolysis. The importance of the alcohol moiety of the substrate ester on enantioselectivity was confirmed: the E value was increased up to 9-fold by using the n-butyl ester instead of the conventional methyl ester. The maximum E value was 180.     

Xanthones from the stems of Cudrania tricuspidata and their inhibitory effects on pancreatic lipase and fat accumulation

Nine new xanthones, cudracuspixanthones I - Q (12–14, 25, 32–36), and 30 known xanthones (1–11, 15–24, 26–31, 37–39) were isolated from the stems of Cudrania tricuspidata (Moraceae). The structures of isolated compounds were established by using 1D and 2D NMR in combination with HR-TOF-MS. Xanthones from the stems of C. tricuspidata exerted pancreatic lipase inhibitory activity. In addition, cudracuspixanthone P (35), a new xanthone, reduced the fat accumulation in liver cells stimulated with fatty acids. Therefore, these compounds might be beneficial in the treatment of metabolic diseases.