Hyperactive antifreeze protein from beetles

We have purified a thermal hysteresis (antifreeze) protein, with up to 100 times the specific activity of fish antifreeze proteins, from the common yellow mealworm beetle, Tenebrio molitor. It is a threonine- and cysteine-rich protein, of relative molecular mass 8,400, composed largely of 12-amino-acid repeats. We estimate that a concentration of roughly 1 mg ml−1 of this protein can account for the 5.5 °C of thermal hysteresis found in Tenebrio larvae (Fig. 1).Figure 1Thermal hysteresis activity of Tenebrio haemolymph as a function of dilution.The standard deviation of each sample (n43) is shown.[graphic not available: see fulltext]