Metal chelate-epoxy bifunctional membranes for selective adsorption and covalent immobilization of a His-tagged protein

Enhancing biocatalyst performance through immobilization of lipase (Eversa® Transform 2.0) on hybrid amine-epoxy core-shell magnetic nanoparticles

Magnetic nanoparticles were functionalized with polyethylenimine (PEI) and activated with epoxy. This support was used to immobilize Lipase (Eversa® Transform 2.0) (EVS), optimization using the Taguchi method. XRF, SEM, TEM, XRD, FTIR, TGA, and VSM performed the characterizations. The optimal conditions were immobilization yield (I.Y.) of 95.04 ± 0.79 %, time of 15 h, ionic load of 95 mM, protein load of 5 mg/g, and temperature of 25 °C. The maximum loading capacity was 25 mg/g, and its stability in 60 days of storage showed a negligible loss of only 9.53 % of its activity. The biocatalyst demonstrated better stability at varying temperatures than free EVS, maintaining 28 % of its activity at 70 °C. It was feasible to esterify free fatty acids (FFA) from babassu oil with the best reaction of 97.91 % and ten cycles having an efficiency above 50 %. The esterification of produced biolubricant was confirmed by NMR, and it displayed kinematic viscosity and density of 6.052 mm2/s and 0.832 g/cm3, respectively, at 40 °C. The in-silico study showed a binding affinity of -5.8 kcal/mol between EVS and oleic acid, suggesting a stable substrate-lipase combination suitable for esterification.

Recent applications and future prospects of magnetic biocatalysts

Magnetic biocatalysts combine magnetic properties with the catalytic activity of enzymes, achieving easy recovery and reuse in biotechnological processes. Lipases immobilized by magnetic nanoparticles dominate. This review covers an advanced bibliometric analysis and an overview of the area, elucidating research advances. Using WoS, 34,949 publications were analyzed and refined to 450. The prominent journals, countries, institutions, and authors that published the most were identified. The most cited articles showed research hotspots. The analysis of the themes and keywords identified five clusters and showed that the main field of research is associated with obtaining biofuels derived from different types of sustainable vegetable oils. The overview of magnetic biocatalysts showed that these materials are also employed in biosensors, photothermal therapy, environmental remediation, and medical applications. The industry shows a significant interest, with the number of patents increasing. Future studies should focus on immobilizing new lipases in unique materials with magnetic profiles, aiming to improve the efficiency for various biotechnological applications.

Expression of His-tagged NADPH-dependent acetoacetyl-CoA reductase in recombinant Escherichia coli BL-21(DE3)

Poly-3-hydroxybutyrate (P(3HB)), a member of the polyhydroxyalkanoate (PHA) family, is a biodegradable polyester with diverse industrial applications. NADPH-dependent acetoacetyl-CoA reductase (phaB) is the enzyme which plays an essential role in P(3HB) synthesis by catalyzing the conversion of the intermediates. The expression of phaB enzyme using the recombinant Escherichia coli BL-21(DE3) and the purification of the synthesized enzyme were studied. The pET-B3 plasmid harbouring the phaB gene derived from Ralstonia eutropha H16, was driven by the lac promoter in E. coli BL-21(DE3). The enzyme was expressed with different induction time, temperatures and cell age. Results showed that the cell age of 4 h, induction time of 12 h at 37°C were identified as the optimal conditions for the enzyme reductase expression. A specific activity of 0.151 U mg-1 protein and total protein concentration of 0.518 mg mg-1 of dry cell weight (DCW) were attained. Affinity chromatography was performed to purify the His-tagged phaB enzyme, in which enhanced the specific activity (14.44 U mg-1) and purification fold (38-fold), despite relative low yield (44.6%) of the enzyme was obtained. The purified phaB showed an optimal enzyme activity at 30°C and pH 8.0. The findings provide an alternative for the synthesis of the reductase enzyme which can be used in the industrial-scale production of the biodegradable polymers.

Ni(II) functionalized polyhedral oligomeric silsesquioxane based capillary monolith for purification of histidine-tagged proteins by immobilized metal affinity micro-chromatography

A new capillary monolithic stationary phase was synthesized for the purification of histidine tagged proteins by immobilized metal affinity micro-chromatography (μ-IMAC). For this purpose, mercaptosuccinic acid (MSA) linked-polyhedral oligomeric silsesquioxane [MSA@poly(POSS-MA)] monolith 300 μm in diameter was obtained by thiol-methacrylate polymerization using methacryl substituted-polyhedral oligomeric silsesquioxane (POSS-MA) and MSA as the thiol functionalized agent in a fused silica capillary tubing. Ni(II) cations were immobilized onto the porous monolith via metal-chelate complex formation with double carboxyl functionality of bound MSA segments. μ-IMAC separations aiming the purification of histidine tagged-green fluorescent protein (His-GFP) from Escherichia coli extract were carried out on Ni(II)@MSA functionalized-poly(POSS-MA) [Ni(II)@MSA@poly(POSS-MA)] capillary monolith. His-GFP was succesfully isolated by μ-IMAC on Ni(II)@MSA@poly(POSS-MA) capillary monolith with the isolation yield of 85 % and the purity of 92 % from E. coli extract. Higher His-GFP isolation yields were obtained with lower His-GFP feed concentrations and lower feed flow rates. The monolith was used for consecutive His-GFP purifications with a tolerable decrease in equilibrium His-GFP adsorption over five runs.

Immobilization of Recombinant Endoglucanase (CelA) from Clostridium thermocellum on Modified Regenerated Cellulose Membrane

Cellulases are being widely employed in lignocellulosic biorefineries for the sustainable production of value-added bioproducts. However, the high production cost, sensitivity, and non-reusability of free cellulase enzymes impede their commercial applications. Enzyme immobilization seems to be a potential approach to address the aforesaid complications. The current study aims at the production of recombinant endoglucanase (CelA) originated from the cellulosome of Clostridium thermocellum in Escherichia coli (E. coli), followed by immobilization using modified regenerated cellulose (RC) membranes. The surface modification of RC membranes was performed in two different ways: one to generate the immobilized metal ion affinity membranes RC-EPI-IDA-Co2+ (IMAMs) for coordination coupling and another to develop aldehyde functional group membranes RC-EPI-DA-GA (AMs) for covalent bonding. For the preparation of IMAMs, cobalt ions expressed the highest affinity effect compared to other metal ions. Both enzyme-immobilized membranes exhibited better thermal stability and maintained an improved relative activity at higher temperatures (50–90 °C). In the storage analysis, 80% relative activity was retained after 15 days at 4 °C. Furthermore, the IMAM- and AM-immobilized CelA retained 63% and 53% relative activity, respectively, after being reused five times. As to the purification effect during immobilization, IMAMs showed a better purification fold of 3.19 than AMs. The IMAMs also displayed better kinetic parameters, with a higher Vmax of 15.57 U mg−1 and a lower Km of 36.14 mg mL−1, than those of AMs. The IMAMs were regenerated via treatment with stripping buffer and reloaded with enzymes and displayed almost 100% activity, the same as free enzymes, up to 5 cycles of regeneration.