Methods for purifying synthetic peptides

Abstract

Methods for making preparations of homogenous peptides are disclosed. In these methods, reversible alterations of the physicochemical properties of the peptides are exploited. In preferred embodiments, the methods include the following sequential steps: (1) exhaustive capping is carried out during solid-phase synthesis of a desired peptide; (2) a cleavable linker is attached to the peptide, (3) a polymer is added to the peptide either by condensation with preformed polymer or by in situ polymerization such that the linker is interposed between the polymer moiety and the peptide moiety of the resultant adduct; alternatively, steps (2) and (3) can be conducted simultaneously by attaching a combination polymer/linker to the peptide; (4) the polymer-peptide adduct is cleaved from the resin; (5) the polymer-peptide adduct is purified from undesired, nonadducted peptides; and (6) the polymer-peptide adduct is cleaved at the linker, and the desired peptide is purified from the polymer. In some cases, it may be desirable to omit step (6) in order to leave the polymer moiety attached to the desired peptide. For example, the polymer-peptide adducts of the present invention are very soluble in water, and therefore can be used to solubilize amphipathic peptides. Additionally, the polymer moieties of the polymer-peptide adducts can elicit immune responses in mammals or birds; thus, the adducts and corresponding antibodies can be used in research protocols to track the peptide moieties of the adducts.