Abstract: An affinity ligand peptide library of IgG constructed on the basis of Protein A affinity model and the application of a design method thereof. According to the Molecular Mechanics—Poisson-Boltzmann surface area (MM/PBSA) method and on the basis of the known human IgG-Protein A complex structure, the hot spots of Protein A that have high affinity for human IgG are obtained analytically, and a Protein A simplified affinity model is built thereof. An affinity peptide library of IgG is constructed including heptapeptide and octapeptide structural modes. On the basis of the peptide structural modes, the types of inserted amino acids that ‘X’ residues represent are further identified using amino acid location method. Then, molecular docking and molecular dynamics simulation methods are used to screen the candidate peptides successively. Finally, the affinity peptide ligands that can effectively purify IgG are identified using affinity chromatography.

Abstract: An affinity ligand peptide library of IgG constructed on the basis of Protein A affinity model and the application of a design method thereof According to the Molecular Mechanics—Poisson-Boltzmann surface area (MM/PBSA) method and on the basis of the known human IgG-Protein A complex structure, the hot spots of Protein A that have high affinity for human IgG are obtained analytically, and a Protein A simplified affinity model is built thereof. An affinity peptide library of IgG is constructed including heptapeptide and octapeptide structural modes. On the basis of the peptide structural modes, the types of inserted amino acids that ‘X’ residues represent are further identified using amino acid location method. Then, molecular docking and molecular dynamics simulation methods are used to screen the candidate peptides successively. Finally, the affinity peptide ligands that can effectively purify IgG are identified using affinity chromatography.

Abstract: A method for protein refolding with an ion exchange resin. The method includes (a) choosing an ion exchange resin that having charged groups with the same sign as a net charge of a denatured protein to be refolded; (b) removing heterogeneous ions from the ion exchange resin by washing the ion exchange resin sequentially with saline solution and deionized water, to prepare the ion exchange resin; (c) mixing the ion exchange resin with a refolding buffer thoroughly, then adding the denatured protein to the refolding buffer and allowing the denatured protein to refold; and then (d) collecting the supernatant by centrifugation or settlement, to obtain a solution containing the refolded protein.

Abstract: A method for protein refolding using a like-charged ion exchange resins as an additive to facilitate protein refolding. The ion exchange resins mentioned herein includes charged group with the same sign as the target protein to be refolded and the method for refolding an unfolded protein. The method has some advantages described as below: firstly, no new impurity is introduced into the final product of protein due to ion exchange resins used in the present invention is insoluble and easy to remove by settlement or centrifugation, secondly; the key material used in the present invention, ion exchange resins, is easy to recycle after regeneration; thirdly, compared with the refolding method by chromatographic techniques, the current method requires no expensive chromatograph facilities and is simple to perform at lower cost, which is a desirable character for preparative refolding of therapeutic proteins expressed in bacteria as inclusion bodies.