Homodimeric and Heterodimeric Aryl Sulfotransferases Catalyze the Sulfuric Acid Esterification of N-Hydroxy-2-acetylaminofluorene

Three aryl sulfotransferases (ASTs) isolated from rat liver catalyze the sulfuric acid esterification of the carcinogen N-hydroxy-2-acetylaminofluorene (N-OH-2AAF). These three ASTs were separated by high resolution anion exchange chromatography and were designated Q1, Q2, and Q3. Q1 and Q2 had high...

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Bibliographic Details
Published in:The Journal of biological chemistry 1995-08, Vol.270 (32), p.18941-18947
Main Authors: Kiehlbauch, Charles C., Lam, Yim F., Ringer, David P.
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Animals
Arylsulfotransferase - chemistry
Arylsulfotransferase - isolation & purification
Arylsulfotransferase - pharmacology
Chromatography, High Pressure Liquid
Hydroxyacetylaminofluorene - metabolism
Kinetics
Male
Molecular Sequence Data
Rats
Rats, Sprague-Dawley
Sulfuric Acids - metabolism
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Summary:Three aryl sulfotransferases (ASTs) isolated from rat liver catalyze the sulfuric acid esterification of the carcinogen N-hydroxy-2-acetylaminofluorene (N-OH-2AAF). These three ASTs were separated by high resolution anion exchange chromatography and were designated Q1, Q2, and Q3. Q1 and Q2 had high N-OH-2AAF sulfonation activity, whereas Q3 showed low activity. Reversed phase high performance liquid chromatography/mass spectrometry analysis showed Q1-Q3 to be comprised of 33,945- and 35,675-Da protein subunits. Q1 contained only the 35,675-Da protein subunit, Q2 contained equal quantities of 33,945- and 35,675-Da subunits, and Q3 contained only the 33,945-Da subunit. The subunit compositions of Q1-Q3 were confirmed by immunochemical analysis. Size exclusion high performance liquid chromatography confirmed that the active quaternary structure of the three isoenzymes was dimeric. Analysis of liver cytosols for the relative contributions of Q1-Q3 to total cytosolic N-OH-2AAF sulfotransferase activity indicated that Q1, Q2, and Q3 accounted for 44, 46, and 10% of the activity, respectively. These results demonstrate the existence of both homodimeric and heterodimeric aryl sulfotransferases and show that two ASTs, a homodimer of 35,675-Da subunits and a heterodimer of a 33,945- and a 35,675-Da subunit, are primarily responsible for hepatic N-OH-2AAF sulfotransferase activity.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.270.32.18941