A random sequential adsorption model for the irreversible binding of Tenebrio molitor antifreeze protein to ice crystals

A class of proteins known as antifreeze proteins (AFPs) appear in some organisms, allowing them to survive in low-temperature environments. These AFPs irreversibly adsorb to the surfaces of ice crystals and reduce the freezing temperature without significantly affecting the equilibrium melting point. Ice crystal growth is inhibited in the temperature gap between the melting point and the non-equilibrium freezing point, referred to as thermal hysteresis (TH). The irreversible adsorption of AFPs on the surfaces of ice crystals has been questioned because it is not consistent with the concentration dependence of the TH activity obtained from experimental studies. In this study, based on adsorption-inhibition theory, a random sequential adsorption model of AFPs was used to investigate the irreversible adsorption of hyperactive AFPs that have been found in the yellow mealworm beetle Tenebrio molitor (TmAFPs). The occupied fractions covered by TmAFP on ice crystal surfaces were obtained. The time and concentration dependence of the TH activity of TmAFP was analyzed. The theoretical results obtained from this model were consistent with reported experimental data. This work provides ideas and a theoretical basis for understanding the TH activity during the irreversible adsorption of AFPs.