[Purification and some properties of D-carbamoylase]

A D-Carbamoylase produced by a strain NO. 2262 was purified to electrophoretic homogeneity with the recovery of 20% activity and the purification factor of 8 fold by three steps including (NH4)2SO4 fractionation, hydrophobic column and pre-packed Hitrap Q HR. It is indicated from the results of nativ-PAGE and SDS-PAGE analysis that the enzyme could be a homogeneous tetramer consisting of four 35 kD subunits. In addition, its optimal pH and optimal temperature are 8.0 and 45 degrees C respectively. The basic kinetic parameters of the enzyme are Km = 1.3 x 10(-3) mol/L and Vmax = 0.33 mumol/min with N-carbamyl-DL-Alanine as the substrate. The effect of bivalent metal ions on the enzyme was showed that Ni2+ could be as an activator, Zn2+ as a powerful inhibitor, while Co2+ had no any influence at all. Its N-terminal sequence is TRQKILAF in turn.