Determination of Mammalian Steroid Sulfatase with 7 a-H”-3 P-Hydroxyandrost-5-enGone Sulfate *

Mammalian steroid sulfatase which cleaves dehydroisoandrosterone sulfate* and certain other steroid sulfates with planar rings A and B, such as sulfates of the 3P-hydroxy-5aandrostane or 5a-pregnane series, was first discovered by Gibian and Bratfisch (1) in ox and rat liver and confirmed by Roy (2). The occurrence and intracellular distribution of the enzyme have been further studied by Roy (3) and by Ney and Ammon (4). The extreme insolubility of this microsomal enzyme and its resistance to solubilization have not permitted extensive purification and separation from the many other enzymes present in the microsomal particle. Investigations by nonisotopic methods into the presence and properties of steroid sulfatase in endocrine tissues were further complicated by the existence of side reactions (3fl01 dehydrogenase and the 17gdehydrogenase) that yielded products not measurable by the Pettenkoffer and Zimmermann reactions. In a preliminary report (5) a method for the determination of steroid sulfatase was described which uses 7o(-H3-dehydroisoandrosterone sulfate as substrate and measures the H3 extracted into toluene as a function of time. The purpose of this paper is to report on the development of the method and on some kinetic data obtained with enzyme from mammalian liver, testis, adrenal, and ovary.