BPS 2022
Mega-Throughput Screening of Large OBOC Non-Natural Peptide Libraries Using Fiber Optic Array Scanning Technology
Michal Avital-Shmilovici
Senior Scientist and Research Lead, SRI International
ABSTRACT
Accessing chemical diversity in the discovery of new peptide sequences as affinity reagents and therapeutics has been greatly accelerated with biologic screening tools such as phage display. Extension in to modified amino acids through the random nonstandard peptide integrated discovery (RaPID) system which integrates genetic code reprogramming with mRNA display technology enables screening of increasingly non-natural polymers. While both methods facilitate the synthesis and screening of massive libraries (10^7-12) such systems are still largely confined to alpha-amino acid backbones. To access more chemically diverse non-natural polymers the one-bead-one-compound (OBOC) method offers the greatest synthetic flexibility and can in principle enable the production of very large libraries, but in practice is generally limited to libraries of 10^4-6 due to cost of synthesis, limitations in screening throughput and the lack of generalizable sequencing tools for non-alpha amino acid backbone polymers. We describe a new methodology that enables the production and screening of OBOC libraries of natural and non-natural peptides up to 50+ residues in length comprising 10^7 to 10^9 compounds. Using a self-readable polymer design that facilitates sequencing sensitivity at fmol scale, libraries can be synthesized on 10 – 20 micron diameter beads to maximize library size while minimizing cost of synthesis. The screening method utilizes a Fiber-optic Array Scanning Technology (FAST), for screening against fluorescent labeled target molecules with an unprecedented throughput of 5 million beads per minute. We have used this approach to identify affinity reagents and PPI inhibitor hits with nanomolar affinities for challenging targets such as KRAS, IL6 and TNFï¡. We have also demonstrated the ability to find protein-glycan interaction competitors in the discovery of novel non-natural peptide carrier molecules for the glycan receptor Asialoglycoprotein Receptor 1 (ASGPR1) for hepatic drug delivery. Recent work on the discovery of affinity agents for the S1 protein of SARS_CoV2 as a means to develop new neutralizing therapeutics will also be presented.
BIO
Dr. Michal Avital-Shmilovici received her PhD in Chemistry from the University of Chicago under the supervision of Professor Stephen Kent, working in chemical synthesis of natural and non-natural proteins. She used modern solid-phase peptide synthesis, native chemical ligation and folding methods to improve understanding of the biology behind large molecule drugs and advance progress in the development of therapeutics.
In 2015, Michal joined the Biosciences Division at SRI International to help establish the Technein Discovery Platform. This platform, based around SRI’s Fiber-optic Array Scanning Technology (FAST), enables the rapid discovery of protein-like synthetic molecules (called TechneinsTM) to be used as therapeutics, diagnostics and targeted delivery agents. As a Principal Scientist, she currently leads the Technein Discovery Platform program and has discovered a pipeline of high-affinity Techneins that are being developed against a wide range of targets for both therapeutic and diagnostic applications.