Conclusions
In this paper, we have successfully developed an ELP-peptide fusion for
the affinity precipitation of the therapeutically relevant small non-mAb
biologic, AdP. Phage biopanning was first used to identify lead peptides
which were then synthesized and evaluated for their binding to the
target using fluorescence polarization. A fusion of the top lead peptide
with ELP was then produced in E. coli and evaluated for its
efficacy to both capture and elute the bioproduct. While binding was
favored at low pH conditions, higher pH values were more useful for
elution. In addition, the use of fluid phase modifiers, in particular
arginine, were shown to further improve the elution behavior. Evaluation
of the ELP-peptide with a crude mixture demonstrated that both high
recovery (83%) and purity (88%) could be achieved using this affinity
precipitation process. While this proof of concept study was successful,
further mutagenesis studies could be carried out to improve both the
binding and elution behavior of the peptide. This work establishes that
peptides identified from phage display can be successfully employed in
an ELP fusion format for the purification of a small therapeutic
biologic by affinity precipitation. The results and approaches presented
in this work can now be extended to other biologics for which there
currently do not exist efficient affinity capture processes.