A multiple sequence alignment was constructed by Clustal Omega for the 95 protein sequences annotated as homologues of arylsulfatases and the 85 protein sequences annotated as homologues of phosphonate monoester hydrolases, respectively. The HMMER software suite was used to derive a profile hidden Markov model from a multiple sequence alignment via the command hmmbuild, and to derive a consensus sequence from a profile hidden Markov model via the command hmmemit.