Three-chain insulin analogs demonstrate the importance of insulin secondary structure to bioactivity

This report describes the chemical synthesis and biological characterization of novel three‐chain insulin analogs with a destabilized secondary structure. The analogs, obtained by chemical synthesis via a single‐chain precursor and selective enzymatic digestion, were used to investigate the role of the highly conserved ‘insulin fold’. Biological characterization through in vitro biochemical signaling showed extremely low activity at each insulin receptor when compared with native insulin. We conclude that the ‘insulin fold’ is a structural foundation that supports insulin biological action. Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd. The secondary structure of insulin is highly conserved across insulin‐related superfamily members. In this study, we utilized novel three‐chain synthetic insulin analogs to demonstrate the importance of the secondary structure to proper insulin receptor interaction.