US Patent 7408030 Purification of immunoglobulins using affinity chromatography and peptide ligands

An immunoglobulin binding peptide having the general formula, from amino terminus to carboxy terminus, of Z-R1—R2—R3—R4—R5—R6—X, is described, wherein: R1 is H or Y; R2 is a hydrophobic, preferentially aromatic, amino acid (for example W, F, Y, V); R3 is a positively charged or aromatic amino acid (for example R, H, F, W); R4 is a hydrophobic or positively charged amino acid (for example G, Y, R, K, L); R5 is a positively charged or aromatic amino acid (for example W, F, R, H, Y); R6 a random amino acid but preferably hydrophobic or negatively charged (for example V, W, L, D, H); X is present or absent and when present is a linking group; and Z is present or absent and when present is a capping group bonded to the N terminus of R1; and wherein the amino acids of said peptide are in D form, L form, or a combination thereof. Methods of using such peptides for the purification of Immunoglobulins are also described.