Effect of ethanol on insulin dimer dissociation

Area of Science:

• Biochemistry
• Molecular Biology
• Physical Chemistry

Background:

• Insulin dimer dissociation is crucial for its biological activity.
• Understanding this process at a molecular level is essential for drug development and biochemical studies.

Purpose of the Study:

• To investigate the molecular mechanisms of insulin dimer dissociation in water and water-ethanol mixtures.
• To quantify the effect of ethanol on the free energy barrier and dissociation pathway of insulin dimers.

Main Methods:

• Biased molecular dynamics simulations were used to compute the free energy surface.
• Analysis of intermediate states and microscopic structural changes in varying ethanol concentrations.
• Solvation analysis of monomers during dissociation.

Main Results:

• Ethanol markedly lowers the activation free energy barrier for dimer dissociation by up to ~50% in 5% water-ethanol solution.
• Ethanol induces significant changes in the dissociation pathway, stabilizing a unique intermediate state.
• A stable intermediate state, with monomers separated by ~3 nm, is observed in water-ethanol mixtures, stabilized by preferential solvent distribution.

Conclusions:

• Ethanol acts as a potent facilitator of insulin dimer dissociation by reducing the free energy barrier.
• The observed stabilization of intermediate states by ethanol-water interactions provides key insights into the dissociation mechanism.
• These findings are vital for understanding hormone activity regulation and developing targeted therapies.