The present invention relates method for purifying antibodies, said method comprising a limited number of steps while still allowing obtaining high yields of purified antibodies with an appropriate degree of purity. Briefly, this method comprises only filtration and precipitation steps, omitting the need for chromatography steps.

Methods are provided for isolation of immunoglobulin G (IgG) from plasma, where IgG is initially fractioned by salt precipitation, followed by successive ion exchange steps in which IgG appears in unbound, flow-through fractions of the ion exchange steps. Some embodiments employ successive anion exchange steps. Other embodiments employ an anion exchange step followed by application of flow-through of the anion exchange step to a cation exchange step, with IgG collected in flow-through fractions from the cation exchange step. IgG is collected at high yield (typically about 75% or greater) and high purity. Avoidance of binding and elution from chromatography media simplifies processing and scale up without sacrificing IgG quality or yield.

A method is provided for purifying physiologically active proteins, especially antibodies, in order to remove impurities such as DNA contaminants and viruses with minimal loss of physiologically active proteins. The physiologically active protein is introduced into an aqueous solution of low conductivity at a pH of below the isoelectric point of the physiologically active protein to precipitate impurities as particles. The particles are removed, leaving a purified physiologically active protein.

A method is provided for purifying physiologically active proteins, especially antibodies, in order to remove impurities such as DNA contaminants and viruses with minimal loss of physiologically active proteins. The physiologically active protein is introduced into an aqueous solution of low conductivity at a pH of below the isoelectric point of the physiologically active protein to precipitate impurities as particles. The particles are removed, leaving a purified physiologically active protein.

Electromagnetic waves are uniformly distributed on the light-receiving surface side by taking advantage of their property of being easily concentrated in sharp parts, and the front area (S.sub.A) on the emission surface side is made larger than the back area (S.sub.B) on the light-receiving surface side (S.sub.A/S.sub.B>1), thereby forming a more moderate electric field region. A reduced gold fine particle group (average particle size: 20 nm) was self-assembled on a transparent polyester resin film and half-submerged and fixed. This base material was repeatedly immersed in an electroless gold plating solution so that gold particles were deposited on the gold fine particles. 10 microliters of a protein solution was added dropwise to this nanostructured substrate, and crystallized by a hanging drop vapor diffusion method.

Compositions of the inventive concept provide a therapeutic protein with less than 2% contamination by the therapeutic protein in denatured form. Such compositions provide enhanced specific activity and improved stability on storage and/or in serum than corresponding therapeutic protein preparations resulting from conventional isolation methods.

Compositions of the inventive concept provide a therapeutic protein with less than 2% contamination by the therapeutic protein in denatured form. Such compositions provide enhanced specific activity and improved stability on storage and/or in serum than corresponding therapeutic protein preparations resulting from conventional isolation methods.

A method for purifying a target peptide may include mixing a peptide product obtained through a peptide synthesis with a solvent in the presence of a sulfonic acid compound to obtain a solid; and performing a solid-liquid separation to collect the solid.

A method for purifying a target peptide may include mixing a peptide product obtained through a peptide synthesis with a solvent in the presence of a sulfonic acid compound to obtain a solid; and performing a solid-liquid separation to collect the solid.

Compositions and methods are provided that simplify isolation of proteins of interest from serum or plasma. Finely divided silica or a similar lipid/lipoprotein binding solid is used in combination with a protein precipitating agent to generate a solution that includes the protein of interest and that can be applied to chromatography media without resulting in significant fouling of the media. The method is particularly suitable for isolation of immunoglobulin G.