Multiple sequence alignment of catalse proteins using the program ClustalW. Accession numbers of the proteins as extracted using the Entrez web service are: NP_036652 (Rattus norvegicus), (Mus musculus), (Sus scrofa), (Bombyx mori), CAB45236 (Homo sapiens), AAH54964 (Xenopus laevis), AAH51626 (Danio rerio), CAA36529 (Drosophila melanogaster), and JN580276 (Hydra vulgaris). The properties of amino acids are identified by shading as follows: No shading indicates fully conserved amino acids, light gray shading indicates strongly conserved residues, and dark gray shading indicates weakly conserved residues.