Insulin Analog with Additional Disulfide Bond Forms a Structurally Secure, Thermodynamically Stable Molecule

Abstract

Insulin is a hormone secreted by the pancreatic cells. In vivo, normal insulin contains 3 disulfide bonds that account for structural instability and low melting point. In this experiment, an insulin analog was attempted to be made mechanically and thermodynamically more stable than human insulin (HI). It was hypothesized that the addition of a fourth disulfide bond (4SS‐insulin) would be more stable as previous attempts at other types of transformational change to the A‐chain and B‐chain were unsuccessful. By adding a fourth disulfide bond in positions A10/B4, the outcome would be a significant clinical application for the treatment of insulin‐dependent diabetes as scientists are constantly trying to find insulin analogs that would potentiate the effects of blood sugar lowering. To experiment, the fourth disulfide bond was successfully formed using yeast as a template. They tested fragility (fibrillation), low pH, and thermodynamic stabilization, finding that the fourth disulfide bond made insulin more mechanically and thermodynamically stable. Once this was complete, in vivo experimentation on rates demonstrated the effect on blood glucose and in vitro experimentation on lipogenesis in rat adipocytes. In vivo, 4SS‐insulin had a longer and more profound effect on blood glucose than HI. In vitro, 4SS‐insulin had a greater affinity for insulin receptors than HI. The Kohler High School MAPS Team used 3‐D modeling and printing technology to examine the relationship between a structurally secure fourth disulfide bond and the thermodynamic stability of an insulin analog in comparison to typical HI. The clinical applicability of this new biomedically engineered 4SS‐insulin is significant. Patients could be able to self‐inject less insulin less frequently, helping with affordability and improved glycemic control. Additionally, the storage of insulin becomes more convenient as 4SS‐insulin can withstand a 34.6 °Celsius increase in melting temperature.PDB: 4EFX