title: Heterogeneity of guinea pig chorion and liver estrogen sulfotransferases.
abstract: The presence of two forms of estrogen sulfotransferase (EST) in 105,000 g cytosols of guinea pig chorion and liver has been established by chromatofocusing via a fast protein liquid chromatographic (FPLC) procedure. The chorion EST forms were eluted at pH 6.2 and 5.4, and the liver forms at 6.1 and 5.3. Each has been further purified by an affinity column step using Agarose-hexane-adenosine-3',5'-diphosphate (PAP-Agarose) gel to achieve up to 386-fold and 77-fold specific activity (SA) increases over cytosol for chorion and liver, respectively. The most highly purified preparations were extremely unstable unless protected by the addition of serum albumin of high purity. Each EST form exhibited an estimated molecular weight of 48-52 KDa by FPLC gel filtration and each acted upon both estrone (E1) and estradiol (E2). Each of these steroids inhibited sulfation of the other. A departure from Michaelis-Menten kinetics occurred, particularly in the case of chorion EST, at steroid substrate concentrations above 0.1-0.15 microM. E2 caused strong substrate inhibition of the most highly purified chorion EST. Chorion EST possessed considerable affinity for E1 and E2.
authors.affiliation: Department of Biochemistry, University of Western Ontario, London, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Hobkirk
mesh_terms: D000818:Animals; D002823:Chorion / Q000201:enzymology*; D002846:Chromatography, Affinity; D003600:Cytosol / Q000201:enzymology; D005260:Female; D006168:Guinea Pigs; D007525:Isoelectric Focusing; D007527:Isoenzymes / Q000302:isolation & purification*; D008099:Liver / Q000201:enzymology*; D011247:Pregnancy; D013379:Substrate Specificity; D015238:Sulfotransferases; D013466:Sulfurtransferases / Q000302:isolation & purification*
chemical_list: D007527:Isoenzymes; D013466:Sulfurtransferases; D015238:Sulfotransferases; C020122:estrone sulfotransferase