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 nuclear fraction is comparable to the total activity per liver in the microsomal fraction. The combined estrone-3-sulfatase activity in the other fractions (lysosomal, mitochondrial, and cytosolic fractions) is negligible 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 values for the nuclear and microsomal estrone-3-sulfatases are 2.5 and 10.1 microM, respectively, suggesting that the nuclear sulfatase has a considerably higher affinity for estrone-3-sulfate than the microsomal sulfatase. Moreover, the nuclear estrone-3-sulfatase is more sensitive to inhibition by several steroids than the microsomal sulfatase. The results suggest that estrone-3-sulfatase in the nuclear fraction is a different isozyme than that in the microsomal fraction.
Zhu
B T
BT
Department of Chemical Biology, College of Pharmacy, Rutgers-State University of New Jersey, Piscataway 08854, USA. baoting@rci.rutgers.edu
Fu
J H
JH
Xu
S
S
Kauffman
F C
FC
Conney
A H
AH
D000818:Animals; D002467:Cell Nucleus / Q000201:enzymology; D005260:Female; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D008862:Microsomes, Liver / Q000201:enzymology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013347:Subcellular Fractions / Q000201:enzymology; D013429:Sulfatases / Q000737:chemistry / Q000378:metabolism*
D007527:Isoenzymes; D013429:Sulfatases; C020121:estrone sulfatase