PROPERTIES OF ASPARTATE-TRANSCARBAMYLASE FROM TAD1, A PSYCHROPHILIC BACTERIAL STRAIN ISOLATED FROM ANTARCTICA

TAD1 is a psychrophilic strain isolated from continental frozen water in Antarctica. Study of aspartate transcarbamylase in the bacterium sh ows an impressive activity of this enzyme at low temperature. Ar 0 deg rees 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 temperat ure results from an increased catalytic efficiency. This property migh t 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. (C) 1998 Federation of European Microbi ological Societies. Published by Elsevier Science B.V. All rights rese rved.