Growth suppression of ice crystal basal face in the presence of a moderate ice-binding protein does not confer hyperactivity

Significance Ice-binding proteins (IBPs) can be considered a prominent example of macromolecules affecting ice growth kinetics. Until now, two groups of IBPs have been described based on their activity as ice growth inhibitors: moderate and hyperactive IBPs. The mechanism underlying these activity differences has not been clarified yet. Although it is commonly believed that hyperactivity is related to growth inhibition of the basal faces of ice crystals, we show that a moderate IBP can also attach to the basal faces and inhibit their growth. Our observations clearly indicate that this moderate IBP occupies a separate position in the classification of IBPs and contribute to our understanding of interaction between macromolecules and ice and more generally, between macromolecules and inorganic crystals.