Single Step Purification of a Small Non-mAb Biologic by Peptide-ELP
based Affinity Precipitation
Abstract
Affinity precipitation using stimulus-responsive biopolymers such as
Elastin-like Polypeptides (ELPs) have been successfully employed for the
purification of monoclonal antibodies. In the current work, we extend
these studies to the development of an ELP-peptide fusion for the
affinity precipitation of the therapeutically relevant small non-mAb
biologic, AdP. A 12-mer affinity peptide ligand (P10) was identified by
a primary phage biopanning followed by a secondary in-solution
fluorescence polarization screen. Peptide P10 and AdP interacted with a
KD of 19.5 µM. A fusion of P10 with ELP was then shown to be successful
in selectively capturing the biologic from a crude mixture. While pH
shifts alone were not sufficient for product elution, the use of pH in
concert with fluid phase modifiers such as NaCl, arginine or ethylene
glycol was successful. In particular, the use of pH 8.5 and an arginine
concentration of 500 mM enabled > 80% product recovery.
The overall process performance evaluated by SDS-PAGE and reversed-phase
UPLC analyses, indicated the successful single-step purification of the
biologic from an E. coli lysate resulting in ~90%
purity and >80% recovery. These results demonstrate that
phage display can be readily employed to identify a peptide ligand
capable of successfully carrying out the purification of a non-antibody
biological product using ELP-based affinity precipitation.