查看更多>>摘要：To efficiently decompose biomass, fungi have developed various enzymatic and non-enzymatic strategies and are a source of versatile biocatalysts. The endoglucanases in glycosyl hydrolase CAZy family 45 (GH45) are known for their small size, a high thermostability and a broad substrate specificity that has been employed in textile and detergent industries. Here we report the heterologous expression and characterisation of an GH45 endoglucanase from the brown rot Fomitopsis pinicola and its direct comparison to an already characterised GH45 from the white rot Phanerochaete chrysosporium. Both enzymes were recombinantly expressed in Pichia pastoris and purified by two chromatographic steps. The biochemical characterisation highlighted the acidophilic character, with an optimal pH of 4, and a preference for amorphous substrates as carboxymethyl cellulose (CMC) and substrates containing beta-1,4-glucans rather than the previously reported beta-1,3/1,4-glucans lichenan and beta-glucan. The dominating products from beta-1,4-glucans were C3-C6 oligosaccharides, whereas from beta-1,3/1,4-glucans glucose was the main reaction product. From the characterisation no differences between the brown rot and the white rot GH45 was evident.
查看更多>>摘要：With the increasing production of polyethylene terephthalate (PET) plastic products, the problem of PET waste has become a serious threat to ecosystem. PET enzymatic biodegradation, due to its environmental friendliness and sustainability, has gradually attracted attention. As a multifunctional hydrolase, cutinase (EC 3.1.1.74) can not only degrade fatty acid esters, soluble synthetic esters, and emulsified triglycerides, but also exhibit potential for PET degradation. In order to enhance the PET degradation activity of cutinase, we functionally screened several PET binding domains, e.g. carbohydrate binding module, anchor peptide, and hydrophobin, that promote the absorption of enzyme to PET substrate, selected Dermaseptin SI (DSI) and fused it onto the N-terminus of Thermobifida fusca cutinase mutant D204C/E253C (Tfuc2), and finally achieved the PET degradation rate up to 57.9% at 70 ?C for 96 h, which was 22.7-fold of that of Tfuc2 itself. These results indicate that the fusion of PET binding domain is a promising strategy to enhance PET enzymatic degradation.
查看更多>>摘要：Enzyme immobilization using metal-organic frameworks (MOFs) as carriers has aroused significant interest owing to the unique pore structure and versatile surface functional groups of MOFs. Catalase (CAT) is an important industrial enzyme that is widely used in the catalytic decomposition of hydrogen peroxide in the fields of food and biological products. In this study, mesoporous MIL-101 (Cr), synthesized through a facile hydro-thermal process, was applied for CAT immobilization for the first time. The immobilization capacity of MIL-101 (Cr) for CAT was studied systematically by batch adsorption tests under different adsorption conditions, including the variation of the solution pH, operation temperature, adsorption time, and initial concentration of CAT. Based on these test findings, the optimum adsorption conditions and maximum adsorption capacity were determined. The adsorption kinetics were simulated to further explore the adsorption mechanism, and they suggest that chemical adsorption, rather than physical adsorption, is the main CAT adsorption mechanism. A comparison of Fourier transform infrared (FT-IR) spectra of MIL-101 (Cr) without and with adsorbed CAT reveals the formation of amide bonding between the-NH of CAT and the uncoordinated-C--O of MIL-101(Cr). Finally, the stability and activity of the immobilized CAT were assessed, and an improved insensitivity against changes in pH and a prolonged storage time demonstrate the enhanced stability of immobilized CAT by MIL-101 (Cr) carriers. This study demonstrates the application of MOFs as functional supports for the efficient immobilization of versatile enzymes.
NSTL
Elsevier