<p>These sequences represent an enzyme that catalyzes the cleavage of the carbon phosphorous bond of a phosphonate. The mechanism depends on the substrate having a carbonyl one carbon away from the cleavage position. This enzyme is a member of the Haloacid Dehalogenase (HAD) superfamily of aspartate-nucleophile hydrolases, and contains a modified version of the conserved catalytic motifs of that superfamily: the first motif is usually DxDx(T/V), here it is DxAxT, and in the third motif the normal conserved lysine is instead an arginine. Additionally, the enzyme from <taxon tax_id="1396">Bacillus cereus</taxon> contains a unique conserved catalytic lysine (pos. 53 [<cite idref="PUB00009540"/>], <db_xref db="SWISSPROT" dbkey="O31156"/> pos. 50) which is involved in the binding and activation of the substrate through the formation of a Schiff base [<cite idref="PUB00009540"/>]. The substrate of this enzyme is the product of 2-aminoethylphosphonate (AEP) transaminase, phosphonoacetaldehyde. This degradation pathway for AEP may be related to its toxic properties which are utilised by microorganisms as a chemical warfare agent.</p>