Studies on sulphatases. 19. The purification and properties of arylsulphatase B of human liver

Abstract

Human-liver arylsulfatase B was considerably purified by a procedure involving acetone-fractionation, treatment with protamine sulfate and adsorption of the enzyme on sintered-glass disks. During the early stages of the procedure the enzyme was markedly affected by buffer concentration and gave anomalous substrate concentration-activity curves. These effects were not obtained with the final enzyme preparation. Comparatively crude preparations of the corresponding ox-liver enzyme exhibited similar anomalies which, however, were not removed by further purification. With dipotassium 2-hydroxy-5-nitrophenyl sulfate as assay substrate some indications of the nature of the ionizing groups which are involved in the formation and subsequent breakdown of the enzyme-substrate complex were obtained from a study of the variation of Km and Vmax with pH. The enzyme showed little activity towards potassium phenyl sulfate and its monosubstituted derivatives; there was appreciable activity towards disubstituted derivatives.