Proteomic methods applied to the analysis of immobilized biocatalysts

Enzyme immobilization inside the porous wood structure: a natural scaffold for continuous-flow biocatalysis

Enzymes are often immobilized on solid supports to enable their recovery from reaction solutions, facilitate their reuse and hence increase cost-effectiveness in their application. Immobilized enzymes may even be used for flow-through applications in continuous processes. However, the synthesis of traditional immobilization scaffolds and immobilization techniques lack sustainability as they are often based on fuel-based materials and tedious synthesis- and immobilization approaches. Here, we present the natural material wood as a green alternative for enzyme immobilization. Its natural structure provides a mechanically stable porous scaffold with a high inner surface area that allows for directional flow-through of liquids. Enzymes were immobilized by nanoparticle-mediated adsorption, a simple, versatile and completely water-based process. The resulting wood–enzyme hybrids were intensely investigated for the model enzyme laccase. Reaction kinetics, as well as catalytic activities at various pH-values, temperatures, and ionic strengths were determined. The wood–enzyme hybrids could quickly and completely be removed from the reaction solution. Hence, they allow for multifold reusability. We show a series of 25 consecutive reaction cycles with a remaining activity in the last cycle of 90% of the maximal activity. Moreover, the anisotropic porosity of wood enabled the application of the hybrid material as a biocatalytic flow-through reactor. Flow-rate dependent productivity of a single-enzyme reaction was determined. Moreover, we show a two-step reaction cascade in continuous flow by the immobilization of the enzymes glucose oxidase and horseradish peroxidase. Therefore, the natural material wood proved to be a promising material for application in continuous-flow biocatalysis.

Green biocatalytic systems for continuous-flow cascade reactions are realized by enzyme immobilization inside the porous wood structure.

Novozym 435: the “perfect” lipase immobilized biocatalyst?

Novozym 435 (N435) is a commercially available immobilized lipase produced by Novozymes with its advantages and drawbacks.

Immobilization of Cholesterol Oxidase: An Overview

Background:

Cholesterol oxidases are bacterial oxidases widely used commercially for their application in the detection of cholesterol in blood serum, clinical or food samples. Additionally, these enzymes find potential applications as an insecticide, synthesis of anti-fungal antibiotics and a biocatalyst to transform a number of sterol and non-sterol compounds. However, the soluble form of cholesterol oxidases are found to be less stable when applied at higher temperatures, broader pH range, and incur higher costs. These disadvantages can be overcome by immobilization on carrier matrices.

Methods:

This review focuses on the immobilization of cholesterol oxidases on various macro/micro matrices as well as nanoparticles and their potential applications. Selection of appropriate support matrix in enzyme immobilization is of extreme importance. Recently, nanomaterials have been used as a matrix for immobilization of enzyme due to their large surface area and small size. The bio-compatible length scales and surface chemistry of nanoparticles provide reusability, stability and enhanced performance characteristics for the enzyme-nanoconjugates.

Conclusion:

In this review, immobilization of cholesterol oxidase on nanomaterials and other matrices are discussed. Immobilization on nanomatrices has been observed to increase the stability and activity of enzymes. This enhances the applicability of cholesterol oxidases for various industrial and clinical applications such as in biosensors.

Mass spectrometric analysis of peptides from an immobilized lipase: focus on oxidative modifications

Liquid chromatography/tandem mass spectrometry (LC/MS/MS) was used to study the primary structure of immobilized Candida antarctica lipase B (Novozym(R)435) without detaching the enzyme from the carrier. The immobilized enzyme packed in a miniature column was subjected to proteolysis and the peptides released were injected into the mass spectrometer for analysis. The set-up was utilized to determine amino acid oxidation after treatment of the biocatalyst with hydrogen peroxide. In total, sequence coverage of more than 90% was obtained, containing almost all of the amino acids sensitive to oxidation. Oxidation of methionine, tryptophan and cystine residues was observed. The flow system also allowed evaluation of the enzyme activity prior to peptide analysis. The developed method is general and should be applicable to other immobilized enzyme systems and to different treatments.