Theory of the rotational contribution to facilitated diffusion

Area of Science:

• Biophysics
• Physical Chemistry
• Biochemistry

Background:

• Facilitated diffusion is crucial for biological transport processes.
• Haemoglobin facilitates the transport of protons and oxygen.
• Previous experiments indicated rotational diffusion impacts proton but not oxygen transport by haemoglobin.

Purpose of the Study:

• To develop a theoretical framework for facilitated transport by rotating carriers.
• To explain the experimental observation of enhanced proton transport due to carrier rotation.
• To investigate the influence of rotational diffusion on carrier-mediated transport.

Main Methods:

• Theoretical development of facilitated transport equations.
• Analysis of carrier rotation and its effect on diffusion.
• Mathematical modeling of proton and oxygen transport by rotating haemoglobin.

Main Results:

• The developed theory confirms that rotational diffusion enhances proton transport.
• Rotational enhancement is significant when the rotational diffusion angle is small relative to the binding time.
• A rotational boundary layer effect was identified in the transport model.
• Oxygen transport was not found to be enhanced by rotational diffusion under the studied conditions.

Conclusions:

• Carrier rotation plays a significant role in the facilitated diffusion of protons by haemoglobin.
• The theoretical model accurately explains experimental findings regarding rotational enhancement.
• The study highlights the importance of considering carrier dynamics in transport phenomena.