Identification of peptide ligands for MAb anti rh-interferon-alpha 2b purification using one-bead-one-peptide libraries

L.V. ROMERO; M.M. MARANI; M. ETCHEVERRIGARAY; F. ALBERICIO; S. A. CAMPERI; O. CASCONE

Pinamar, Buenos Aires, Argentina

Congreso; XLI Reunión Anual de la Sociedd Argentina de Investigación Bioquímica y Biología Molecular; 2005

Sociedd Argentina de Investigación Bioquímica y Biología Molecular

Nowadays affinity chromatography with protein A as the ligand is preferred for industrial purification of MAbs. However, protein A is prone to degradation and thermolabile. Short peptides, instead, are suitable ligands due to their higher stability. In this work, a simple and non-expensive method for affinity ligand selection over a combinatorial peptide library using mass spectrometry sequencing (MS/MS) is described. A one-octapeptide-one-bead library was synthesized on the PEG-based solid support Aminomethyl ChemMatrixTM with HMBA as the linker. The HMBA inertness to TFA allowed side chain deprotection without releasing the peptide from the resin. The library was synthesized by the Divide-Couple-Recombine (DCR) method using Fmoc chemistry. An immunoaffinity screening against a MAb anti-rh-IFN-a2b over the library containing the octapeptides XXXXGGGG was performed. Beads showing a positive reaction were mechanically isolated and subjected to ammonia/THF cleavage. Free peptides were sequenced by MS/MS. Five peptides were identified as possible ligands for the MAb. They will be synthesized, attached to Sepharose and their ability to purify the MAb will be assessed.