Purification and properties of a novel recombinant human hybrid interferon, delta-4 alpha 2/alpha 1

Prokaryotic-expressed porcine IFNα1-THYα1 fusion proteins exert IFN and THY activities in vitro

Combined use of interferon (IFN) and thymosin (THY) holds a stronger antiviral effect than when applied individually because of their coordination and complementary action. In this study, prokaryotic expressed porcine IFNα1 (poIFNα1) or the porcine IFNα1-THYα1 fusion protein coding with the Escherichia coli preferred codon sequences connected by the three different linkers were gained in the unlabeled pRSFDDuet-1 expression systems and purified using the strong anion-exchange chromatography and hydrophobic chromatography (among which, one was digested by thrombin because the cleavage site was included in the linker). Then, the activities of IFN and THY in the fusion protein were detected using the cytopathic effect inhibition assay and T-cell activity assays. SDS PAGE and western blotting results showed that the poIFNα1 or the three poIFNα1-THYα1 fusion proteins with three different linkers were expressed solubly in E. coli. The poIFNα1 protein and three types of poIFNα1-THYα1 fusion proteins with >90% purity were gained. The poIFNα1-LinkerB-THYα1 fusion protein showed the highest interferon activity compared with the others (P < 0.001), and the poIFNα1-LinkerA-THYα1 fusion protein highest thymosin activity (P < 0.05). In this study, a preliminary experiment was conducted for the expression of the poIFNα1 and THYα1 fusion proteins.

Interferon-alpha hybrids

The alpha-interferons (IFN-alpha) belong to a family of polypeptides comprising several subtypes. Using recombinant DNA technology, it has been possible to create IFN hybrids that provide novel combinations of the amino acid residues from the parental protein sequences. They have been used to study structure-activity relationships of IFN-alpha and interactions with the IFN-alpha receptor, and to create analogs of natural IFNs with novel properties for potential therapeutic application. The biological data obtained with these hybrids are now evaluated in terms of the published structural and homology models of IFN-beta and -alpha.

Cytokines: an overview

Cytokines are a broad, heterogeneous group of proteins and polypeptides that regulate intercellular communication. Examples of cytokines include interleukins, interferons, colony-stimulating factors, and a variety of growth factors. The preparation of large quantities of highly purified recombinant cytokines has provided a basis for their biological and physicochemical characterization. The pleiotropic biological effects of these factors are expressed through binding to specific, high-affinity cell-surface receptors. Although they are different in amino acid sequence, cytokines have a number of biological and physicochemical properties in common.

Solubility as a function of protein structure and solvent components

This review deals with ways of stabilizing proteins against aggregation and with methods to determine, predict, and increase solubility. Solvent additives (osmolytes) that stabilize proteins are listed with a description of their effects on proteins and on the solvation properties of water. Special attention is given to areas where solubility limitations pose major problems, as in the preparation of highly concentrated solutions of recombinant proteins for structural determination with NMR and X-ray crystallography, refolding of inclusion body proteins, studies of membrane protein dynamics, and in the formulation of proteins for pharmaceutical use. Structural factors relating to solubility and possibilities for protein engineering are analyzed.