Rapid generation of hypervariable chemical libraries
Rapid generation of hypervariable chemical libraries
John S. Albin, Gha Young Lee, Corey Johnson, Dimuthu A. Vithanage, Wayne Vuong, Bradley L. Pentelute
Abstract
The utility of combinatorial polyamide libraries for selection-based drug discovery is limited by the methods commonly used to generate polyamide libraries. Under one-bead, one-compound synthesis approaches, library generation is time and reagent intensive, requiring days to weeks for custom library generation. This imposes a bottleneck on total throughput while also limiting the incorporation of variable regions into longer polyamide chains. Moreover, the ability to place only a single compound on any one bead imposes a physical limit to library content of around a billion (109) members. Here, we adapt a semi-automated flow platform to the synthesis of combinatorial polyamide libraries based on building block mixtures, where the adjustment of building block molar ratios normalizes relative incorporation to target levels despite intrinsically different building block reaction rates. Under this methodology, the time and reagent usage required to generate any one library is identical to that required for the synthesis of a single peptide (minutes to hours), while achievable library size rises to quintillions (1018) of members per library. A system for the prediction of the molar adjustments needed for any building block based on the building block gyration radius permits the facile incorporation of noncanonical amino acids, thus preserving complete synthetic control over library content. We further develop a scalable analytical framework for the deconvolution of libraries of effectively any size in virtually any polyamide chain length. Semi-automated flow synthesis of combinatorial polyamide libraries thus decreases the time and reagents needed for custom library synthesis by approximately 1 order of magnitude while simplifying the incorporation of variable regions into larger scaffolds and dramatically expanding the number of compounds accessible per library.