Enantioselective hydrolysis of (R,S)-naproxen 2,2,2-trifluoroethyl ester in water-saturated solvents via lipases from Carica pentagona Heilborn and Carica papaya

Valorization of levulinic acid by esterification with 1-octanol using a novel biocatalyst derived from Araujia sericifera

Levulinic acid, which can be obtained from biomass, has sparked great interest as a biologically-based chemical building block with wide versatility and potential. Its esterification with alcohols of different chain lengths is a promising valorization process for obtaining esters with various applications in the areas of biofuels/biolubricants, food and cosmetics, among others. In this work, the enzymatic esterification of levulinic acid and 1-octanol using a biocatalyst derived from Araujia sericifera latex was studied in systems with and without solvent. The influence of the molar ratio between alcohol and acid (ranging from 2:1-1:9), the biocatalyst loading (between 7.5 % and 17.5 % relative to the acid), the volume of n-heptane used as reaction solvent (from 0 to 4 ml), and the reaction time (6 hours) were investigated. The activity and stability of the biocatalyst in successive uses were also analyzed. A conversion of 49 % was achieved when the reaction was carried out in a solvent-free system, using an alcohol/acid molar ratio of 1:7 and after 5 h of reaction. On the other hand, the conversion was 65.1 % when the reaction was conducted in a system containing 1 ml of n-heptane as solvent, an alcohol/acid molar ratio of 1:8, and 5 h of reaction. In both cases, a temperature as low as 30 °C and an agitation speed of 300 RPM were used.

Plant lipases: partial purification of Carica papaya lipase

Lipases from plants have very interesting features for application in different fields. This chapter provides an overview on some of the most important aspects of plant lipases, such as sources, applications, physiological functions, and specificities. Lipases from laticifers and particularly Carica papaya lipase (CPL) have emerged as a versatile autoimmobilized biocatalyst. However, to get a better understanding of CPL biocatalytic properties, the isolation and purification of individual C. papaya lipolytic enzymes become necessary. In this chapter, a practical protocol for partial purification of the latex-associated lipolytic activity from C. papaya is given.

Resolution of (R,S)-(+/-)-glycidyl butyrate with immobilized Y-11 Trichosporon capitatum lipase in gelatin-containing microemulsion-based organogels

An extracellular lipase produced by the strain of Y-11 Trichosporon capitatum was purified to homogeneity by ammonium sulfate precipitation and four chromatographic steps. The purified lipase showed enhanced activity when it was immobilized in gelatin-containing microemulsion-based organogels. Furthermore, the resolution of (R,S)-(+/-)-glycidyl butyrate by this immobilized lipase gave a product of (S)-(-)-glycidol with approximately 98% ee (E=96). By using chiral HPLC separation, (S)-(-)-glycidol was obtained in enantiopure form. Scaled-up reaction in 2l shake flask was also performed and the repeated use of 15 times of immobilized Y-11 T. capitatum lipase resulted in little loss in its activity (4.8%).

Implication of substrate-assisted catalysis on improving lipase activity or enantioselectivity in organic solvents

In comparison with the biocatalyst engineering and medium engineering approaches, very few examples have been reported on using the substrate engineering approach such as substrate-assisted catalysis (SAC) for naturally occurring or engineered lipases and serine proteases to improve the enzyme activity and enantioselectivity. By employing lipase-catalyzed hydrolysis of (R,S)-naproxen esters in water-saturated isooctane as the model system, we demonstrate the proton shuttle device to the leaving alcohol of the substrate as a new means of SAC to effectively improve the lipase activity or enantioselectivity. The result cannot only provide a strong evidence for the rate-limiting proton transfer for the bond-breaking of tetrahedron intermediate of the acylation step, but also sheds light for performing the hydrolysis, transesterification or aminolysis in organic solvents for the ester substrate that originally lipases cannot catalyze, but now can after introducing the device.

Altering lipase activity and enantioselectivity in organic media using organo-soluble bases: Implication for rate-limiting proton transfer in acylation step

With the hydrolytic resolution of (R,S)-naproxen 2,2,2-trifluoroethyl esters via a partially purified papaya lipase (PCPL) in water-saturated isooctane as the model system, the enzyme activity, and enantioselectivty is altered by adding a variety of organo-soluble bases that act as either enzyme activators (i.e., TEA, MP, TOA, DPA, PY, and DMA) or enzyme inhibitors (i.e., PDP, DMAP, and PP). Triethylamine (TEA) is selected as the best enzyme activator as 2.24-fold increase of the initial rate for the (S)-ester is obtained when adding 120 mM of the base. By using an expanded Michaelis-Menten mechanism for the acylation step, the kinetic analysis indicates that the proton transfer for the breakdown of tetrahedral intermediates to acyl-enzyme intermediates is the rate-limiting step, or more sensitive than that for the formation of tetrahedral intermediates when the enzyme activators of different pKa are added. However, no correlation for the proton transfers in the acylation step is found when adding the bases acting as enzyme deactivators.

Carica papaya lipase (CPL): an emerging and versatile biocatalyst

In recent years, the Carica papaya lipase (CPL) is attracting more and more interest. This hydrolase, being tightly bonded to the water-insoluble fraction of crude papain, is thus considered as a "naturally immobilized" biocatalyst. To date, several CPL applications have already been described: (i) fats and oils modification, derived from the sn-3 selectivity of CPL as well as from its preference for short-chain fatty acids; (ii) esterification and inter-esterification reactions in organic media, accepting a wide range of acids and alcohols as substrates; (iii) more recently, the asymmetric resolution of different non-steroidal anti-inflammatory drugs (NSAIDs), 2-(chlorophenoxy)propionic acids, and non-natural amino acids. Taking into account the novelty and the current interest of the topic, this review aims to highlight the origin, features, and applications of the C. papaya lipase, with the objective to prompt research groups to further investigate the spectra of applications that this emerging and versatile CPL could have in the future.