Lysosomal arylsulfatases A and B from horse blood leukocytes: purification and physico-chemical properties

Lysosomal arylsulfatases A and B (aryl-sulfate sulfohydrolases, EC 3.1.6.1) from horse leukocytes were purified about 680-fold and 70-fold, respectively, starting from a crude extract of the azurophil and specific granules of leukocytes, by affinity, ion exchange, and gel filtration chromatography. Purified arylsulfatase A displayed anomalous kinetics, a pH optimum at 5.2, an isoelectric point at 4.3, and a Km value for p-nitrocatechol sulfate (pNCS) of 0.37 mM. This enzyme was found to exist in two association states depending on pH: a high molecular weight form at pH 5.0 and a low molecular weight form at pH 7.5. Arylsulfatase B displayed normal kinetics, a pH optimum at 5.8, two isoelectric points at pH 8.6 and 8.9, and a Km value for pNCS of 3.38 mM. The thermostability of the two enzymes was different: arylsulfatase B was found to be more stable than arylsulfatase A. Arylsulfatase A was inhibited by sulfate, sulfite, silver, magnesium, manganese and calcium ions and arylsulfatase B by chloride, sulfate, sulfite and silver ions.