DIFFERENT BIOCHEMICAL-PROPERTIES OF NUCLEAR AND MICROSOMAL ESTRONE-3-SULFATASES - EVIDENCE FOR THE PRESENCE OF A NUCLEAR ISOZYME

In female rats, total estrone-3-sulfatase activity per liver in the nu clear fraction is comparable to the total activity per liver in the mi crosomal fraction. The combined estrone-3-sulfatase activity in the ot her fractions (lysosomal, mitochondrial, and cytosolic fractions) is n egligible and only accounts for <5% of the total nuclear or microsomal sulfatase activity. Nuclear and microsomal estrone-3-sulfatases have different pH optima (pH 8.0 and 7.2, respectively). The apparent Km va lues for the nuclear and microsomal estrone-3-sulfatases are 2.5 and 1 0.1 mu M, respectively, suggesting that the nuclear sulfatase has a co nsiderably higher affinity for estrone-3-sulfate than the microsomal s ulfatase. Moreover, the nuclear estrone-3-sulfatase is more sensitive to inhibition by several steroids than the microsomal sulfatase, The r esults suggest that estrone-3-sulfatase in the nuclear fraction is a d ifferent isozyme than that in the microsomal fraction. (C) 1998 Academ ic Press.