Fast and efficient protein purification using membrane adsorber systems

Engineered Design of the E-Helix Structure on Ferritin Nanoparticles

Insertion of an immunogenic epitope at the C-terminus of ferritin has shown the potential to produce a stable and efficacious vaccine. There is however limited understanding of how C-terminus insertion affects ferritin protein stability. The E-helix at the C-terminus has attracted interest because there are contradictory reports as to whether it has a role in protein stabilization. Here, we report, for the first time, combining molecular dynamics simulation (MDS) with experiment to engineer the design of the E-helix at the C-terminus of engineered human ferritin heavy chain (F₁) inserted with Epstein-Barr nuclear antigen 1 (EBNA1, E₁) and flexible linker (L₃) residues (to afford F₁L₃E₁). Hot spots on the E-helix of the C-terminus were predicted by MDS at aa 167 (Glu) and aa 171 (Asp). Five (5) variants of F₁L₃E₁ were constructed by considering hot spots and alteration of electrostatic or hydrophobic interfaces, namely, (1) C1, hot spots substituted with noncharged residue Gln; (2) C2, hot spots substituted with positively charged residue Arg; (3) C3, hydrophobic residues substituted with the most hydrophobic residues Val and Ile; (4) C4, hydrophobic residues substituted with the most hydrophilic residues Gln and Asn; and (5) C5, a heptad repeat structure in the E-helix disrupted by substituting "a" and "d" heptad residues with noncharged polar residue Gln. It was found that the E-helix is essential to maintain integrated protein stability and that changing the hydrophobic interface (C3 and C4) had more significant effects on protein folding and stability than changing the electrostatic interface (C1 and C2). It was confirmed by both MDS and experiment that variants C1, C2, and C5 were able to fold to form stable conformational structures with protein surface hydrophobicity similar to that of F₁L₃E₁. However, they are less thermally stable than F₁L₃E₁. Significant changes in hydrophobicity drove significant protein aggregation for variants C3 and C4. It is concluded that the molecular design of the C-terminus in engineered ferritin, especially the E-helix, is important to ensure the epitope-based chimeric vaccine is safe (aggregate free) and efficacious.

Green solvents and technologies for oil extraction from oilseeds

Oilseeds are crucial for the nutritional security of the global population. The conventional technology used for oil extraction from oilseeds is by solvent extraction. In solvent extraction, n-hexane is used as a solvent for its attributes such as simple recovery, non-polar nature, low latent heat of vaporization (330 kJ/kg) and high selectivity to solvents. However, usage of hexane as a solvent has lead to several repercussions such as air pollution, toxicity and harmfulness that prompted to look for alternative options. To circumvent the problem, green solvents could be a promising approach to replace solvent extraction. In this review, green solvents and technology like aqueous assisted enzyme extraction are better solution for oil extraction from oilseeds. Enzyme mediated extraction is eco-friendly, can obtain higher yields, cost-effective and aids in obtaining co-products without any damage. Enzyme technology has great potential for oil extraction in oilseed industry. Similarly, green solvents such as terpenes and ionic liquids have tremendous solvent properties that enable to extract the oil in eco-friendly manner. These green solvents and technologies are considered green owing to the attributes of energy reduction, eco-friendliness, non-toxicity and non-harmfulness. Hence, the review is mainly focussed on the prospects and challenges of green solvents and technology as the best option to replace the conventional methods without compromising the quality of the extracted products.

Preparation of bioactive soluble human leukemia inhibitory factor from recombinant Escherichia coli using thioredoxin as fusion partner

Leukemia inhibitory factor (LIF) is a polyfunctional cytokine with numerous regulatory effects in vivo and in vitro. In stem cell cultures it is the essential media supplement for the maintenance of pluripotency of embryonic and induced pluripotent stem cells. With regard to large scale cultures of these cells, LIF is needed in high quality and quantity and represents the major cost determining factor (90%) of the culture media. In this report, we describe a novel production and purification process for human LIF (hLIF) from recombinant Escherichia coli cultures. hLIF was cloned into pET32b and expressed as soluble protein in fusion with thioredoxin. After purification based on membrane adsorber technology, the fusion protein was cleaved using TEV protease. Released, soluble hLIF was subsequently purified by cation exchange chromatography and successfully tested for its biological activity using suspension cultures of murine embryonic and induced pluripotent stem cells. Our novel protocol for the production of recombinant hLIF is very suitable and effective for the production of poorly soluble proteins through expression in fusion with the solubilizing partner thioredoxin.