Structural and immunological relationships among mammalian arylsulfatase A enzymes

Structural and immunological properties of numerous arylsulfatase A enzymes (EC 3.1.6) were examined in order to assess the relationships among these enzymes in animals. Arylsulfatase A enzymes from all animals bind to a Concanavalin A-Sepharose column, consistent with the conclusion that they are all glycoproteins. At pH 7.5 the apparent mol. wts of the enzymes are 80-182 kDa, while at pH 4.5 the mammalian arylsulfatase A enzymes dimerize and exhibit apparent mol. wts in the range of 297-348 kDa, but the enzymes from opossum and other lower classes of animals do not aggregate at pH 4.5. The mammalian arylsulfatase A enzymes, which aggregate at pH 4.5, also bind to rabbit liver arylsulfatase A monomers immobilized on an Affi-Gel 10 matrix. The arylsulfatase A enzymes that were studied all exhibit the anomalous kinetic behavior regarded as characteristic of these enzymes. However, not all of the inactivated enzymes are reactivated by sulfate ions. Goat antiserum raised against homogeneous rabbit liver arylsulfatase A cross-reacts with all of the mammalian enzymes in Ouchterlony gel diffusion experiments, whereas the enzymes from lower classes of animals do not cross-react. Quantitative immunoprecipitation experiments demonstrate that the mammalian enzymes are very similar to each other, with greater than 60% primary sequence homology indicated, while arylsulfatase A from opossum and other lower classes of animals show only a partial immunological similarity with the mammalian enzymes. Taken together, the data suggest that the active site of the enzyme and the structural features of the protein are highly conserved during the evolution of the enzyme molecule.(ABSTRACT TRUNCATED AT 250 WORDS)