Thermal hysteresis activity as a function of antifreeze protein concentration (mg/mL). Active antifreeze variants are: WT (○), A16K (○), A19K (▾), A22K (▿). Inactive antifreeze variants are: A17K (▪), A21K (□), and A25K (♦). Each data point represents the mean of three determinations and the vertical bars represent the standard deviation.