Enhancement of the activity and enantioselectivity of lipase by sol-gel encapsulation immobilization onto β-cyclodextrin-based polymer

Co-immobilization of glucose oxidase and catalase in silica inverse opals for glucose removal from commercial isomaltooligosaccharide

In this work, glucose oxidase (GOD) and catalase (CAT) were co-immobilized on novel silica inverse opals (IO-SiO₂) through sol-gel process. The immobilized bi-enzyme system named GOD/CAT@IO-SiO₂ was successfully fabricated and characterized. Morphology characterization indicated that GOD/CAT@IO-SiO₂ had hierarchical porous structure, and the pore diameter of macroporous and mesoporous were 500±50nm and 6.8nm, respectively. The macrospores were connected through windows of 100±30nm. The results of stability tests indicated that both acid (or base) resistance and thermal tolerance of GOD/CAT@IO-SiO₂ were improved. When GOD/CAT@IO-SiO₂ was used to remove glucose from commercial isomaltooligosaccharide (IMO), the immobilized bi-enzyme system exhibited the good performance. The removal efficiency of glucose reached up to 98.97% under the conditions of GOD/CAT activity ratio of 1:30, the amount of enzyme of 68.8mg, reaction time of 9.39h, reaction temperature of 35.2°C and pH of 7.05. After reused 6 times, 79.19% of removal efficiency could be still retained. The present work demonstrates that the immobilized bi-enzyme (GOD/CAT@IO-SiO₂) is not only a very promising system for glucose removal but also has great potential for applications in production of gluconic acid, preparation of biosensors, enzyme bioreactors, etc.

Bioengineering toward direct production of immobilized enzymes: A paradigm shift in biocatalyst design

The need for cost-effectively produced and improved biocatalysts for industrial, pharmaceutical and environmental processes is steadily increasing. While enzyme properties themselves can be improved via protein engineering, immobilization by attachment to carrier materials remains a critical step for stabilization and process implementation. A new emerging immobilization approach, the in situ immobilization, enables simultaneous production of highly active enzymes and carrier materials using bioengineering/synthetic biology of microbial cells. In situ enzyme immobilization holds the promise of cost-effective production of highly functional immobilized biocatalysts for uses such as in bioremediation, drug synthesis, bioenergy and food processing.

Immobilization of Brassica oleracea chlorophyllase 1 (BoCLH1) and Candida rugosa lipase (CRL) in magnetic alginate beads: an enzymatic evaluation in the corresponding proteins

Enzymes have a wide variety of applications in diverse biotechnological fields, and the immobilization of enzymes plays a key role in academic research or industrialization due to the stabilization and recyclability it confers. In this study, we immobilized the Brassica oleracea chlorophyllase 1 (BoCLH1) or Candida rugosa lipase (CRL) in magnetic iron oxide nanoparticles-loaded alginate composite beads. The catalytic activity and specific activity of the BoCLH1 and CRL entrapped in magnetic alginate composite beads were evaluated. Results show that the activity of immobilized BoCLH1 in magnetic alginate composite beads (3.36±0.469 U/g gel) was higher than that of immobilized BoCLH1 in alginate beads (2.96±0.264 U/g gel). In addition, the specific activity of BoCLH1 beads (10.90±1.521 U/mg protein) was higher than that immobilized BoCLH1 in alginate beads (8.52±0.758 U/mg protein). In contrast, the immobilized CRL in magnetic alginate composite beads exhibited a lower enzyme activity (11.81±0.618) than CRL immobilized in alginate beads (94.83±7.929), and the specific activity of immobilized CRL entrapped in magnetic alginate composite beads (1.99±0.104) was lower than immobilized lipase in alginate beads (15.01±1.255). A study of the degradation of magnetic alginate composite beads immersed in acidic solution (pH 3) shows that the magnetic alginate composite beads remain intact in acidic solution for at least 6 h, indicating the maintenance of the enzyme catalytic effect in low-pH environment. Finally, the enzyme immobilized magnetic alginate composite beads could be collected by an external magnet and reused for at least six cycles.

Increasing the activity and enantioselectivity of lipases by sol-gel immobilization: further advancements of practical interest

The entrapment of lipases in hydrophobic silicate matrices formed by sol-gel mediated hydrolysis of RSi(OCH3)3/Si(OCH3)4 as originally reported in 1996 has been improved over the years by a number of modifications. In the production of second-generation sol-gel lipase immobilizates, a variety of additives during the sol-gel process leads to increased activity and enhanced stereoselectivity in esterifying kinetic resolution. Recent advances in this type of lipase immobilization are reviewed here, in addition to new results regarding the sol-gel entrapment of the lipase from Burkholderia cepacia. It constitutes an excellent heterogeneous biocatalyst in the acylating kinetic resolution of two synthetically and industrially important chiral alcohols, rac-sulcatol and rac-trans-2-methoxycyclohexanol. The observation that the catalyst can be used 10 times in recycling experiments without losing its significant activity or enantioselectivity demonstrates the practical viability of the sol-gel approach.

Parameters Affecting the Performance of Immobilized Enzyme

Enzyme immobilization has been investigated to improve lipase properties over the past few decades. Different methods and various carriers have been employed to immobilize enzyme. However, the application of enzymatic technology in large scale is rarely seen during the industrial process. The main obstacles are a high cost of the immobilization and the poor performance of immobilized lipase. This review focuses on the current status of enzyme immobilization, which aims to summarize the latest research on the parameters affecting the performance of immobilized enzyme. Particularly, the effect of immobilization methods, immobilization carriers, and enzyme loading has been discussed.

Practical protocols for lipase immobilization via sol-gel techniques

Lipases can be efficiently entrapped in the pores of hydrophobic silicates by a simple and cheap sol-gel process in which a mixture of a hydrophobic alkylsilane RSi(OCH3)3 and Si(OCH3)4 is hydrolyzed under basic conditions in the presence of the enzyme. Additives such as isopropanol, polyvinyl alcohol, cyclodextrins, ionic liquids or surfactants enhance the efficiency of this type of lipase-immobilization. The main area of application of these heterogeneous biocatalysts concerns esterification or transesterification in organic solvents, ionic liquids, or supercritical carbon dioxide. Rate enhancements (relative to the traditional use of lipase powders) of several orders of magnitude have been observed, in addition to higher thermal stability. The lipase-immobilizates are particularly useful in the kinetic resolution of chiral esters, enantioselectivity often being higher than what is observed when using the commercial forms of these lipases (powder or classical immobilizates). Thus, due to the low price of sol-gel entrapment, the excellent performance of the lipase-immobilizates, and the ready recyclability, the method is industrially viable.

Sol-gel entrapped Candida antarctica lipase B--a biocatalyst with excellent stability for kinetic resolution of secondary alcohols

Sol-gel entrapment is an efficient immobilization technique that allows preparation of robust and highly stable biocatalysts. Lipase from Candida antarctica B was immobilized by sol-gel entrapment and by sol-gel entrapment combined with adsorption on Celite 545, using a ternary silane precursor system. After optimization of the immobilization protocol, the best enzyme loading was 17.4 mg/g support for sol-gel entrapped lipase and 10.7 mg/g support for samples obtained by entrapment and adsorption. Sol-gel immobilized enzymes showed excellent values of enantiomeric ratio E and activity when ionic liquid 1-octyl-3-methyl-imidazolium tetrafluoroborate was used as additive. Immobilization increased the stability of the obtained biocatalysts in several organic solvents. Excellent operational stability was obtained for the immobilized lipase, maintaining unaltered catalytic activity and enantioselectivity during 15 reuse cycles. The biocatalysts were characterized using scanning electron microscopy (SEM) and fluorescence microscopy. The improved catalytic efficiency of entrapped lipases recommends their application for large-scale kinetic resolution of optically active secondary alcohols.