The influence of adsorption orientation on the statistical mechanics model of type I antifreeze protein: The coverage rate

• We construct a deeper statistical mechanical study on the coverage rate of AFPIs.
• The relationship between coverage rate and adsorption orientation for AFPIs is given.
• The coverage rate is related to the AFP’s adsorption orientation.
• The coverage rate is affected by the AFP chemical potential.
• The AFP–ice interaction also influences the coverage rate.

Based on the statistical mechanics model, the coverage rate of the type I antifreeze protein (AFP) on the surface of ice-crystal in a protein solution is studied by including the adsorption orientation, as well as both the AFP–ice and AFP–water hydrophobic interactions. As an example, the computed results for HPLC-6 are given and discussed. It is shown that the coverage rate increases with the AFP concentration for the dilute protein solutions. The effect of the adsorption orientation of AFP molecules on the coverage rate cannot be ignored. Including the adsorption orientation enhances the coverage rate when the AFP solution is very dilute, but reduces it for the slightly thick solution. The stronger the AFP–ice and AFP–water hydrophobic interactions are, the larger the coverage rate is.