Reaction rate enhancement by surface diffusion of adsorbates.

Area of Science:

• Biophysical Chemistry
• Surface Science
• Computational Biology

Background:

• Ligand capture by surface targets occurs via bulk diffusion or surface diffusion after adsorption.
• Understanding these capture mechanisms is vital for biological processes like receptor-ligand interactions.

Purpose of the Study:

• To model and analyze the kinetics of ligand capture by a surface target considering both bulk and surface diffusion.
• To investigate the influence of diffusion coefficients and adsorption/desorption rates on the overall capture efficiency.

Main Methods:

• Solved a steady-state boundary value problem using numerical computation.
• Incorporated bulk diffusion (D), surface diffusion (Ds), and kinetic rate constants (ka, kd) for adsorption/desorption.
• Analyzed the impact of geometrical dimensions on capture rates.

Main Results:

• The rate of surface capture depends non-linearly on diffusion coefficients (D, Ds) and kinetic rates (ka, kd).
• Both the equilibrium constant (Keq = ka/kd) and individual kinetic rates (ka, kd) are critical for capture efficiency.
• The combination of surface adsorption and diffusion enhances the total ligand capture rate.

Conclusions:

• Surface diffusion and adsorption kinetics play a significant role in ligand-target interactions.
• The findings provide a framework for predicting reaction rates in biological systems.
• Applicable to membrane-bound receptor clusters and immobilized enzymes.