Insulin Analogues with Altered Insulin Receptor Isoform Binding Specificities and Enhanced Aggregation Stabilities

Insulin
is a lifesaver for millions of diabetic patients. There
is a need for new insulin analogues with more physiological profiles
and analogues that will be thermally more stable than human insulin.
Here, we describe the chemical engineering of 48 insulin analogues
that were designed to have changed binding specificities toward isoforms
A and B of the insulin receptor (IR-A and IR-B). We systematically
modified insulin at the C-terminus of the B-chain, at the N-terminus
of the A-chain, and at A14 and A18 positions. We discovered an insulin
analogue that has Cα-carboxyamidated Glu at B31 and Ala at B29
and that has a more than 3-fold-enhanced binding specificity in favor
of the “metabolic” IR-B isoform. The analogue is more
resistant to the formation of insulin fibrils at 37 °C and is
also more efficient in mice than human insulin. Therefore, [AlaB29,GluB31,amideB31]-insulin may be interesting
for further clinical evaluation.