Meanwhile, using the web-server EzyPred [41] at http://www. csbio.sjtu.edu.cn/bioinf/EzyPred/ and the protein sequence information, it was identified that NDM-1 is a member of hydrolases enzyme family (acting on carbon-nitrogen bonds other than peptide bonds), and so is 1ko3. Since both NDM-1 and 1ko3 belong to a same enzyme family with the same action mechanism, and their sequence identity is higher than 40%, it is quite reasonable to use the crystal structure of 1ko3 [40] as a template to develop the 3D structure of NDM-1 via homology modeling.