Temperature-dependent viscosity dominated transport control through AQP1 water channel

Area of Science:

• Biophysics
• Physical Chemistry
• Molecular Biology

Background:

• Aquaporins (AQP1) are water channels crucial for cellular hydration.
• Previous studies suggested proton and hydronium ion exclusion by AQP1.
• The precise mechanisms governing ion transport exclusion remain incompletely understood.

Purpose of the Study:

• To provide a supplementary explanation for proton and hydronium ion exclusion in AQP1.
• To investigate the role of temperature-dependent viscosity in controlling ion transport through AQP1.
• To explore potential size effects influencing ion transport blockage.

Main Methods:

• Utilized verified transition state theory to calculate temperature-dependent viscosity.
• Analyzed activation energy and activation volume considering sub-nano domain roughness.
• Performed numerical simulations to model ion transport behavior under varying viscosity conditions.

Main Results:

• High viscosity (e.g., pitch) at room temperature effectively blocks proton/hydronium ion transport through AQP1, mimicking solid-state behavior.
• Low viscosity (e.g., water) at room temperature allows proton/hydronium ion transport, preventing exclusion.
• Demonstrated a potential size-dependent effect contributing to ion transport blockage in AQP1.

Conclusions:

• Temperature-dependent viscosity is a dominant factor controlling proton and hydronium ion transport in AQP1.
• The findings offer a novel mechanistic insight into ion exclusion by aquaporins.
• Predicted results highlight the importance of viscosity in biological transport phenomena, with no prior experimental viscosity data for AQP1.