Differentiation between Myrosulphatase and the Arylsulphatases

Abstract

THE presence in the seeds of certain Cruciferae of myrosulphatase, an enzyme capable of liberating sulphuric acid from potassium myronate (sinigrin), was first observed by Neuberg and Wagner¹. Afterwards Neuberg and Wagner² claimed to have detected a similar enzyme in certain horse and rabbit tissues. These authors observed only slight hydrolysis of phenyl sulphate by horse liver suspensions and no hydrolysis of potassium myronate by mushroom arylsulphatase, and hence concluded that myrosulphatase and arylsulphatase were distinct enzymes. However, it has recently become clear³ that there are present in Nature two types of arylsulphatase, one of which shows little affinity and activity towards phenyl-, p-acetylphenyl- and p-nitrophenyl sulphate but considerable affinity and activity towards 2-hydroxy-5-nitrophenyl sulphate (nitro-catechol sulphate). At least two enzymes of this type are now known to occur in mammalian tissues^4–6, and it was of interest to determine whether they could have been responsible for the myrosulphatase activity observed by Neuberg and Wagner². We have therefore compared the activities towards potassium myronate and nitrocatechol sulphate of various mammalian liver preparations and of the myrosulphatase-rich seeds of black and white mustard (Sinapis niger and S. alba).