(131f) Purification of Therapeutic Proteins By Affinity Precipitation Using Peptide Conjugated Smart Biopolymers

While chromatographic bioprocessing is the dominant mode of separation for biological products, there is an ongoing search for more cost-effective and scalable processes to address the increasing diversity of therapeutic biomolecules and their increasing titers. Affinity precipitation using smart biopolymers has generated much interest recently for its potential for the simultaneous recovery and purification of biological products. The current work focuses on designing affinity peptides against therapeutic proteins followed by the recombinant engineering of elastin like polypeptide (ELP)-peptide conjugates to develop affinity precipitation processes for proteins. Peptides were designed using epitope mapping as well as high throughput approaches such as phage display. Promising leads were then examined using microarray screening and fluorescence polarization in order to establish peptides with sufficient binding affinity as well as elutability using appropriate modifications in the fluid phase conditions. ELP-peptide constructs against model proteins and proteins of therapeutic importance were recombinantly engineered and their efficacy for purifying the proteins by affinity precipitation were evaluated. Further, the effects of different factors on the precipitation process were studied, such as (i) peptide presentation on the ELP, (ii) peptide affinity towards target protein, (iii) absence and presence of amino acid linkers between the peptide and ELP and (iv) nature and length of these linkers. This study will help to develop design heuristics for ELP based constructs to facilitate effective protein purification by affinity precipitation.