Discovery of a long-acting glucagon-like peptide-1 analog with enhanced aggregation propensity

In the course of our search for new GLP-1 analogs, we screened a number of [Ser⁸]-GLP-1 analogs using the C-terminal helix 3 of the albumin binding domain 3 of protein G from bacterial Streptococcal G strain 148 (G148-ABD3) as appendage. Our efforts led to the discovery of [Ser⁸]-GLP-1 (7-35)-GVKALIDEILAA-NH₂, peptide 6, as a long-acting GLP-1 analog with enhanced self-associated aggregation. Peptide 6 showed enhanced stability in rat and human plasma and an extended half-life of 5.4 h with good bioavailability in rats and subsequently prolonged therapeutic effects in diabetic mice. Analytical ultracentrifugation and TLC suggest that 6 remains oligomeric in the circulation, which accounts for its extended in vivo half-life. The present work shows the possible enhancement of medium-sized oligopeptides aggregation propensity and highlights the potential advantages of peptide aggregates for long-acting peptide drugs.