Solvent Dependent Activity of Candida Antarctica lipase B and its Correlation with a Regioselective Mono Aza-Michael Addition- Experimental and Molecular Dynamics Simulation Studies

With the aim of gaining understanding of the molecular basis of Candida antarctica lipase B (CALB) catalyzed regioselective mono aza-Michael addition of Benzhydrazide to Diethyl maleat (DEM) we decided to carry out molecular dynamics (MD) simulation studies in parallel with our experimental study. We found a correlation between the activity of CALB and the choice of solvent. Our study showed that solvent affects the performance of the enzyme due to the binding of solvent molecules to the enzyme active site region, and the solvation energy of substrates in the different solvents. We found that CALB is only active in nonpolar solvent (i.e. Hexane), and therefore we investigated the influence of Hexane on the catalytic activity of CALB for the reaction. The results of this study and related experimental validation from our studies have been discussed here.

Deep Eutectic Solvents- a New Additive in the Encapsulation of Lipase B from Candida antarctica: Biocatalytic Applications

The enzymes encapsulation in sol-gel matrix can be improved using some additive acting on enzyme activity and/or stability. Ionic liquids, poly-hydroxy compounds, sugars, etc. have been previously reported as additives....

Effect of Functional Group on the Catalytic Activity of Lipase B from Candida antarctica Immobilized in a Silica-Reinforced Pluronic F127/α-Cyclodextrin Hydrogel

Surface modification plays a key role in the fabrication of highly active and stable enzymatic nanoreactors. In this study, we report for the first time the effect of various functional groups (epoxy, amine, trimethyl, and hexadecyl) on the catalytic performance of lipase B from Candida antarctica (CALB) incorporated within a monolithic supramolecular hydrogel with multiscale pore architecture. The supramolecular hydrogel formed by host-guest interactions between α-cyclodextrin (α-CD) and Pluronic F127 was first silicified to provide a hierarchically porous material whose surface was further modified with different organosilanes permitting both covalent anchoring and interfacial activation of CALB. The catalytic activity of nanoreactors was evaluated in the liquid phase cascade oxidation of 2,5-diformylfuran (DFF) to 2,5-furandicarboxylic acid (FDCA) under mild conditions. Results showed that high FDCA yields and high efficiency conversion of DFF could be correlated with the ability of epoxy and amine moieties to keep CALB attached to the carrier, while the trimethyl and hexadecyl groups could provide a suitable hydrophobic-hydrophilic interface for the interfacial activation of lipase. Cationic cross-linked β-CD was also evaluated as an enzyme-stabilizing agent and was found to provide beneficial effects in the operational stability of the biocatalyst. These supramolecular silicified hydrogel monoliths with hierarchical porosity may be used as promising nanoreactors to provide easier enzyme recovery in other biocatalytic continuous flow processes.

Modification of Silica Xerogels with Polydopamine for Lipase B from Candida Antarctica Immobilization

Silica xerogels have been proposed as a potential support to immobilize enzymes. Improving xerogels’ interactions with such enzymes and their mechanical strengths is critical to their practical applications. Herein, based on the mussel-inspired chemistry, we demonstrated a simple and highly effective strategy for stabilizing enzymes embedded inside silica xerogels by a polydopamine (PDA) coating through in-situ polymerization. The modified silica xerogels were characterized by scanning and transmission electron microscopy, Fourier tranform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and pore structure analyses. When the PDA-modified silica xerogels were used to immobilize enzymes of Candida antarctica lipase B (CALB), they exhibited a high loading ability of 45.6 mg/gsupport, which was higher than that of immobilized CALB in silica xerogels (28.5 mg/gsupport). The immobilized CALB of the PDA-modified silica xerogels retained 71.4% of their initial activities after 90 days of storage, whereas the free CALB retained only 30.2%. Moreover, compared with the immobilization of enzymes in silica xerogels, the mechanical properties, thermal stability and reusability of enzymes immobilized in PDA-modified silica xerogels were also improved significantly. These advantages indicate that the new hybrid material can be used as a low-cost and effective immobilized-enzyme support.

Synthesis, Biological Activity, and In silico Study of Bioesters Derived from Bixin by the CALB Enzyme

Biocatalysis is a branch of biotechnology that aims at the chemical transformation of a compound by using enzymes of known specificity. There are already several studies that use combinations of organic origin and enzymes as catalysts. The enzymatic sources are diverse and can be found in microorganisms, animals, vegetables, or commercial (enzymes isolated). The enzyme Candida antarctica lipase B (CALB), of microbial origin, commercially available and with high catalytic activity, can perform esterification reactions, obtaining expressive results. These biocatalytic reactions can contribute to the development of energy products, such as biofuels and pharmaceuticals, such as cosmetics and pharmaceuticals. In this context, the present project aims to esterify with the enzyme Candida antarctica lipase B (CALB), a natural product known as bixin, a dye extracted from the pericarp of annatto seeds (Bixa orellana L.) to verify its biological properties and in silico evidence of its cholesteric activity.

Enhancing the Methanol Tolerance of Candida antarctica Lipase B by Saturation Mutagenesis for Biodiesel Preparation

Methanol tolerance of a lipase is one of the important factors affecting its esterification ability in biodiesel preparation. By B factor indicated prediction of Candida antarctica lipase B (CalB) surface amino acids, 8 sites (Val139, Ala146, Leu147, Pro218, Val286, Ala287, Val306, and Gly307) with high B value indicating more flexibility were chosen to perform saturation mutagenesis. High-methanol-tolerant variants, CalB-P218W and -V306N, created larger haloes on emulsified tributyrin solid plate including 15% (v/v) methanol and showed 19% and 31% higher activity over CalB-WT (wild type), respectively. By modeling, a newly formed hydrogen bond in CalB-V306N and hydrophobic force in CalB-P218W contributing more stability in protein may have resulted in increased methanol tolerance. CalB-P218W and -V306N transesterified the soybean oil into biodiesel at 30 °C by 85% and 89% yield, respectively, over 82% by CalB-WT for 24 h reactions. These results may provide a basis for molecular engineering of CalB and expand its applications in fuel industries. The as-developed semi-rational method could be utilized to enhance the stabilities of many other industrial enzymes.