Destabilization of Insulin Hexamer in Water-Ethanol Binary Mixture

Area of Science:

• Biochemistry
• Structural Biology
• Computational Chemistry

Background:

• Insulin hexamer is the storage form of insulin, a crucial hormone regulating blood glucose.
• Understanding how external factors affect insulin hexamer stability is vital for metabolic health.

Purpose of the Study:

• To investigate the structural impact of ethanol on insulin hexamer integrity.
• To elucidate the mechanism of ethanol interaction with insulin hexamer at a molecular level.

Main Methods:

• X-ray crystallography to determine structural changes.
• Molecular dynamics simulations to analyze ethanol-protein interactions and dynamics.
• Dynamic light scattering experiments to validate computational findings.

Main Results:

• Ethanol molecules replace water within the insulin hexamer cavity.
• Ethanol exchange between bulk and cavity occurs with a free energy cost.
• High ethanol concentrations induce large-scale fluctuations, destabilizing the native protein structure.
• Structural perturbations observed at lower ethanol concentrations, consistent with experimental data.

Conclusions:

• Ethanol interaction compromises insulin hexamer structural integrity.
• These findings suggest a general mechanism for amphiphilic cosolvent-induced changes in macromolecular assemblies.
• Such changes can have significant consequences for cellular homeostasis.