Life under extreme conditions : aspects of evolutionary adaptation to temperature in crustacean proteases

The kinetic properties of a trypsin-like protease - based on cleavage of an artificial substrate - were investigated in several crustacean species from the Weddell Sea and compared to those obtained from species from tropical, temperate and subarctic regions. Decisive steps of thermal acclimation occurred in the lower temperature range, resulting in pronounced cold adaptation of the Antarctic benthic species; this becomes evident from lowered activation energies of the trypsin-like proteases and in comparatively high enzymic activities at 0 degree C. In contrast, species living at high ambient temperatures are more favoured by thermostability at higher temperatures rather than by a change of activation energy.