Sulfatases (EC 3.1.6.-) are enzymes that hydrolyze various sulfate esters. The sequence of different types of sulfatases are available. These enzymes are:

• Arylsulfatase A (EC 3.1.6.8) (ASA), a lysosomal enzyme which hydrolyzes cerebroside sulfate.
• Arylsulfatase B (EC 3.1.6.12) (ASB), a lysosomal enzyme which hydrolyzes the sulfate ester group from N-acetylgalactosamine 4-sulfate residues of dermatan sulfate.
• Arylsulfatase C (ASD).
• Arylsulfatase E (ASE).
• Steryl-sulfatase (EC 3.1.6.2) (STS) (arylsulfatase C), a membrane bound microsomal enzyme which hydrolyzes 3-β-hydroxy steroid sulfates.
• Iduronate 2-sulfatase precursor (EC 3.1.6.13) (IDS), a lysosomal enzyme that hydrolyzes the 2-sulfate groups from non-reducing-terminal iduronic acid residues in dermatan sulfate and heparan sulfate.
• N-acetylgalactosamine-6-sulfatase (EC 3.1.6.4), an enzyme that hydrolyzes the 6-sulfate groups of the N-acetyl-D-galactosamine 6-sulfate units of chondroitin sulfate and the D-galactose 6-sulfate units of keratan sulfate.
• Choline sulfatase (EC 3.1.6.6) (gene betC), a bacterial enzyme that converts choline-O-sulfate to choline.
• Glucosamine-6-sulfatase (EC 3.1.6.14) (G6S), a lysosomal enzyme that hydrolyzes the N-acetyl-D-glucosamine 6-sulfate units of heparan sulfate and keratan sulfate.
• N-sulphoglucosamine sulphohydrolase (EC 3.10.1.1) (sulphamidase), the lysosomal enzyme that catalyzes the hydrolysis of N-sulfo-d-glucosamine into glucosamine and sulfate.
• Sea urchin embryo arylsulfatase (EC 3.1.6.1).
• Green alga arylsulfatase (EC 3.1.6.1), an enzyme which plays an important role in the mineralization of sulfates.
• Arylsulfatase (EC 3.1.6.1) from Escherichia coli (gene aslA), Klebsiella aerogenes (gene atsA) and Pseudomonas aeruginosa (gene atsA).
• Escherichia coli hypothetical protein yidJ.

It has been shown that all these sulfatases are structurally related [1,2,3].

As signature patterns for that family of enzymes we have selected the two best conserved regions. Both regions are located in the N-terminal section of these enzymes. The first region contains a conserved arginine which could be implicated in the catalytic mechanism; it is located four residues after a position that, in eukaryotic sulfatases, is a conserved cysteine which has been shown [4] to be modified to 2-amino-3-oxopropionic acid. In prokaryotes, this cysteine is replaced by a serine.