This enzyme catalyses the deamination of asparagine to yield aspartic acid and an ammonium ion, resulting in a depletion of free circulatory asparagine in plasma. The enzyme from Yersinia pestis is type I L-asparageinase. The overall fold is similar to that of type II L-asparageinase of homotetrameric (dimer of intimate dimers) and the most of catalytic residues are conserved. However type I enzyme is just an intimate dimer, a half of that of type II L-asparageinase. The other key difference is the presence of the active-site flexible loop spanning a 14 – 28 beta-hairpin in the N-terminus including catalytic residues Thr14 and Tyr24. In type II enzyme, this loop serves as a mobile gate to the active site suggesting that in type I, this loop also serves as a gate but more restrictively.