Determination of leakage from antibody adsorbent: composition analysis and pH effect.

To study the leakage at different solution pH values, IgG Sepharose 6FF®, a commercially available immunoadsorbent, was used as a model. The leaked substance consists of three parts: (1) ligands and its fragments; (2) ligands plus matrix fragments in which ligands are chemically attached to the adsorbent matrix; and (3) matrix fragments. Buffer solution pH values had a great effect on both the kinetics and the amount of ligand leakage.

PEGylation of proteins in organic solution: a case study for interferon beta-1b.

Conventional protein PEGylation is carried out in aqueous solution. However, some hydrophobic proteins seem to be stable in organic solution. In this study, a novel approach of PEGylating IFN-β-1b in an organic solution of 2-butanol (2-BuOH) was investigated.

Deliberate manipulation of the surface hydrophobicity of an adsorbent for an efficient purification of a giant molecule with multiple subunits.

Hydrophobic interaction chromatography (HIC) is often an inevitable step for a satisfying purification in giant vaccine molecules production. But great mass and activity loss associated with poor purity often occur simultaneously. In this paper, high purity and high bioactivity recovery for the HIC process of hepatitis B surface antigen (rHBsAg) purification were achieved through manipulation of surface hydrophobicity of the adsorbent.

[Purification and characterization of recombinant human lactoferrin expressed in a cattle mammary bioreactor].

Novel ion exchange adsorbents were synthesized by immobilizing sulfopropyl derivative onto homemade highly cross-linked agarose beads. The effects of different ligand densities (from 0.05 to 0.

Analysis of gelatin plasma substitutes in blood based on detection of hydroxyproline derivatives.

The gelatin plasma substitute is often polydisperse and heterogenous, making it difficult to determine the elimination rate and half-life in the body. In this study, one method was developed based on quantitative determination of hydroxyproline derivatives. Two plasma substitutes were prepared by succinylation and genipin-crosslinking, respectively.

PEGylation markedly enhances the in vivo potency of recombinant human non-glycosylated erythropoietin: a comparison with glycosylated erythropoietin.

Recombinant human non-glycosylated erythropoietin (rh-ngEpo) expressed in E. coli was attached to polyethylene glycol (PEG) chains with different sizes and structures. The pharmacokinetic properties and in vivo potency of the PEGylated protein were investigated and comparisons were drawn between the conjugates and glycosylated recombinant Epo (rhEpo).

Efficient preparation and PEGylation of recombinant human non-glycosylated erythropoietin expressed as inclusion body in E. coli.

Recombinant human erythropoietin produced by mammalian cells contains about 40% carbohydrates which maintain its stability and long residence in body. However, mammalian derived Epo has low yields and high costs of production. In this article, a cost-effective strategy of producing non-glycosylated Epo from Escherichia coli and then PEGylating it to replace the role of sugar chains was investigated.

Cooperative effects of urea and L-arginine on protein refolding.

The use of low concentrations of urea, guanidinium chloride or arginine has been reported in the literature to increase protein refolding and yield of active proteins by suppressing aggregate formation. However, no studies have yet examined whether these substances can exert synergistic or cooperative effects when used in combination. In this work, a comparative study was carried out on refolding of recombinant human granulocyte colony-stimulating factor (rhG-CSF) in the presence of different concentrations of urea, guanidinium chloride or arginine.

Different effects of L-arginine on protein refolding: suppressing aggregates of hydrophobic interaction, not covalent binding.

Arginine is one of the most favorable additives in protein refolding. However, arginine does not work for certain disulfide-bond-containing proteins, which is not yet well explained. In this work, refolding of three proteins in the presence of 0-2 M arginine was investigated and compared.

Identification of an oxidative refolding intermediate of recombinant consensus interferon from inclusion bodies and design of a two-stage strategy to promote correct disulfide-bond formation.

Dilution refolding of recombinant consensus IFN (interferon) from inclusion bodies suffers from low yield. A stable intermediate was found to mix with the correct product and to have an antiviral activity of less than 10% of the latter. This intermediate would form precipitates upon removal of the precipitation inhibitor arginine.