Arylsulfatase B of human lung. Isolation, characterization, and interaction with slow-reacting substance of anaphylaxis.

Arylsulfatase B was separated from arylsulfatase A in extracts of human lung tissue by anion exchange chromatography and further purified by gel filtration and cation exchange chromatography. Arylsulfatase B of human lung was similar to that enzyme in other tissues and species, exhibiting an apparent mol wt of approximately 60,000, a pH optimum for cleavage of 4-nitrocatechol sulfate (pNCS) of 5.5-6.0, and a sensitivity to inhibition by phosphate ions and especially pyrophosphate in the presence of NaCl. Human lung arylsulfatase B inactivated slow-reacting substance of anaphylaxix (SRS-A) in a linear time-dependent reaction in which the rate was determined by the enzyme-to-substrate ratio. Cleavage of pNCS by human lung arylsulfatase B was competitively suppressed by SRS-A. The finding that human lung tissue contains predominately arylsulfatase B discloses a potential regulatory mechanism for inactivation of SRS-A at or near the site of its generation.