Cloning, high expression and purification of recombinant human intereferon-beta-1b in Escherichia coli

Solubilization of Human Interferon β-1b Inclusion Body Proteins by Organic Solvents

Purposes: Solubilization of inclusion bodies expressed in E. coli is a critical step during manufacturing of recombinant proteins expressed as inclusion bodies. So far, various methods have been used for solubilization and purification of inclusion body proteins to obtain active proteins with high purity and yield. The aim of this study was to examine the benefit of organic solvents such as alcohols in solubilization of recombinant interferon β-1b inclusion bodies.

Methods: Effect of important parameters inclusion pH, concentration and type of denaturant and concentration of alcoholic solvents were optimized to formulate a suitable solubilization buffer and investigate their effect on solubilization of interferon β-1b inclusion bodies.

Results: Our findings showed the acidic pH in the range of 2-3 is more suitable than alkaline pH >12 for solubilization and achieving higher content of interferon β-1beta and pure recombinant protein. We have also demonstrated that 1% SDS acts better than 2M urea to solubilize Inclusion body proteins of interferon β-1b at pH of 2-3. The interferon concentration was 2.35 mg per 100 mg IB when we used 40% (v/v) 1-propanol and 20% (v/v) 2-butanol into the buffer solution as well.

Conclusion: The optimized method provides gentile condition for solubilization of inclusion body at high protein concentration and purity with a degree of retention of native secondary structure which makes this method valuable to be used in production and research area.

Recombinant 3-Hydroxy 3-Methyl Glutaryl-CoA Reductase from Candida glabrata (Rec-CgHMGR) Obtained by Heterologous Expression, as a Novel Therapeutic Target Model for Testing Synthetic Drugs

The enzyme 3-hydroxy-3-methyl-glutaryl CoA reductase (HMGR) is a glycoprotein of the endoplasmic reticulum that participates in the mevalonate pathway, the precursor of cholesterol in human and ergosterol in fungi. This enzyme has three domains: transmembrane, binding, and soluble. In this study, we expressed and purified the soluble fraction of the HMGR enzyme from Candida glabrata (CgHMGR) in an Escherichia coli heterologous system and used it as a model for studying its inhibitory activity. The soluble fraction of CgHMGR was fused to the maltose binding protein (MBP), purified, and characterized. Optimal pH was 8.0, and its optimal temperature activity was 37 °C. The k _m and V _max for the HMG-CoA were 6.5 μM and 2.26 × 10^-3 μM min^-1, respectively. Recombinant CgHMGR was inhibited by simvastatin presenting an IC₅₀ at 14.5 μM. In conclusion, our findings suggest that the recombinant HMGR version from C. glabrata may be used as a study model system for HMGR inhibitors such as statins and newly synthesized inhibitor compounds that might be used in the treatment of hypercholesterolemia or mycosis.

High-yield reactivation of anionic tobacco peroxidase overexpressed in Escherichia coli

Anionic tobacco peroxidase (TOP) is extremely active in chemiluminescence reaction of luminol oxidation without addition of enhancers and more stable than horseradish peroxidase under antibody conjugation conditions. In addition, recombinant TOP (rTOP) produced in Escherichia coli is known to be a perfect direct electron transfer catalyst on electrodes of various origin. These features make the task of development of a high-yield reactivation protocol for rTOP practically important. Previous attempts to reactivate the enzyme from E. coli inclusion bodies were successful, but the reported reactivation yield was only 14%. In this work, we thoroughly screened the refolding conditions for dilution protocol and compared it with gel-filtration chromatography. The impressive reactivation yield in the dilution protocol (85%) was achieved for 8 μg/mL solubilized rTOP protein and the refolding medium containing 0.3 mM oxidized glutathione, 0.05 mM dithiothreitol, 5 mM CaCl2, 5% glycerol in 50 mM Tris-HCl buffer, pH 9.6, with 1 μM hemin added at the 24th hour of incubation. A practically important discovery was a 30-40% increase in the reactivation yield upon delayed addition of hemin. The reactivation yield achieved is one of the highest reported in the literature on protein refolding by dilution. The final yield of purified active non-glycosylated rTOP was ca. 60 mg per L of E. coli culture, close to the yield reported before for tomato and tobacco plants overexpressing glycosylated TOP (60 mg/kg biomass) and much higher than for the previously reported refolding protocol (2.6 mg per L of E. coli culture).

Capillary gel electrophoresis for the quantification and purity determination of recombinant proteins in inclusion bodies

In this work, a high-resolution CGE method for quantification and purity determination of recombinant proteins was developed, involving a single-component inclusion bodies (IBs) solubilization solution. Different recombinant proteins expressed as IBs were used to show method capabilities, using recombinant interferon-β 1b as the model protein for method validation. Method linearity was verified in the range from 0.05 to 0.40 mg/mL and a determination coefficient (r(2) ) of 0.99 was obtained. The LOQs and LODs were 0.018 and 0.006 mg/mL, respectively. RSD for protein content repeatability test was 2.29%. In addition, RSD for protein purity repeatability test was 4.24%. Method accuracy was higher than 90%. Specificity was confirmed, as the method was able to separate recombinant interferon-β 1b monomer from other aggregates and impurities. Sample content and purity was demonstrated to be stable for up to 48 h. Overall, this method is suitable for the analysis of recombinant proteins in IBs according to the attributes established on the International Conference for Harmonization guidelines.

3D domain swapping causes extensive multimerisation of human interleukin-10 when expressed in planta

Heterologous expression platforms of biopharmaceutical proteins have been significantly improved over the last decade. Further improvement can be established by examining the intrinsic properties of proteins. Interleukin-10 (IL-10) is an anti-inflammatory cytokine with a short half-life that plays an important role in re-establishing immune homeostasis. This homodimeric protein of 36 kDa has significant therapeutic potential to treat inflammatory and autoimmune diseases. In this study we show that the major production bottleneck of human IL-10 is not protein instability as previously suggested, but extensive multimerisation due to its intrinsic 3D domain swapping characteristic. Extensive multimerisation of human IL-10 could be visualised as granules in planta. On the other hand, mouse IL-10 hardly multimerised, which could be largely attributed to its glycosylation. By introducing a short glycine-serine-linker between the fourth and fifth alpha helix of human IL-10 a stable monomeric form of IL-10 (hIL-10(mono)) was created that no longer multimerised and increased yield up to 20-fold. However, hIL-10(mono) no longer had the ability to reduce pro-inflammatory cytokine secretion from lipopolysaccharide-stimulated macrophages. Forcing dimerisation restored biological activity. This was achieved by fusing human IL-10(mono) to the C-terminal end of constant domains 2 and 3 of human immunoglobulin A (Fcα), a natural dimer. Stable dimeric forms of IL-10, like Fcα-IL-10, may not only be a better format for improved production, but also a more suitable format for medical applications.