This family includes a diverse range of phosphoesterases [1],including protein phosphoserine phosphatases, nucleotidases,sphingomyelin phosphodiesterases and 2'-3' cAMPphosphodiesterases as well as nucleases such as bacterial SbcDSwiss:P13457 or yeast MRE11 Swiss:P32829. The most conservedregions in this superfamily centre around the metal chelatingresidues.