Crystal structure of human arylsulfatase A: the aldehyde function and the metal ion at the active site suggest a novel mechanism for sulfate ester hydrolysis

A study was conducted on the three-dimensional structure of human lysosomal arylsulfatase A (ASA) and a mechanism for the hydrolysis of sulfate esters. The findings indicate the presence of a 2-fold disordered aldehyde group with the possible contribution of an aldehyde hydrate, -CH(OH)2, with gem-hydroxyl groups. The results also confirm the functional importance of the unusually modified amino acid.