Properties of aspartate transcarbamylase fromTAD1, a psychrophilic bacterial strain isolated from Antarctica

Abstract
TAD1 is a psychrophilic strain isolated from continental frozen water in Antarctica. Study of aspartate transcarbamylase in the bacterium shows an impressive activity of this enzyme at low temperature. At 0 degree C, its activity is up to 26% of its maximal activity observed at 30 degrees C. In comparison with the Escherichia coli enzyme, some of its kinetic properties suggest that this high activity at low temperature results from an increased catalytic efficiency. This property might result from a discrete modification localized at the catalytic site, since this psychrophilic enzyme is as stable as its Escherichia coli homologue at high temperature.