Identification of a Novel Amino Acid Motif Responsible for Peptide Aggregation in vitro.

Abstract

Peptides and their derivatives comprise a substantial sector of drug development initiatives due to their specific biological activities and broad chemical versatility. Among the challenges of peptide drug development is a reduction in peptide solubility that leads to peptide aggregation. This dramatically reduces a peptide’s biological availability and prevents its further testing in vivo.Here we report a physicochemical analysis of peptides that inhibit the CMG helicase, the main replicative helicase within the cell. We demonstrate that the inhibitory peptides had a pronounced propensity to form aggregates in vitro by utilizing light microscopy and a fluorescence‐based peptide aggregation assay. By applying a peptide chase approach and abovementioned testing assays, we identified a short amino acid motif of X‐Leu‐Met‐Leu‐X that was responsible for peptide aggregation. Amino acid substitutions at these key residues were studied to confirm their contribution towards aggregation. Interestingly, substitution of either Leucine residues with Serine residues dramatically increased peptide solubility.