Formation of 2-amino-3-methylimidazo[4,5-f]quinoline- and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline-sulfamates by cDNA-expressed mammalian phenol sulfotransferases.
In rat liver cytosol systems, 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) were converted into their sulfamates in the presence of 3'-phosphoadenosine 5'-phosphosulfate at rates of 51.2 and 50.7 pmol/min/mg cytosol in the male, and 23.7 and 22.5 pmol/min/mg cytosol in the female, respectively. IQ-sulfamate formation was low (0.24 pmol/min/mg cytosol) in human liver cytosols, and MeIQx-sulfamate was not detected (< 0.1 pmol/min/mg cytosol). These results suggest only a minor contribution of IQ- and MeIQx-sulfamate formation to the detoxification of both heterocyclic amines in humans. Using sulfotransferase cDNA-expression systems, a rat ST1A1 arylsulfotransferase has been shown to catalyze the formation of the sulfamates, suggesting a role of the ST1A type of sulfotransferase in the N-sulfation of heterocyclic amines.
Ozawa
S
S
Department of Pharmacology, School of Medicine, Keio University, Tokyo.
Nagata
K
K
Yamazoe
Y
Y
Kato
R
R
D000818:Animals; D015239:Arylsulfotransferase / Q000235:genetics* / Q000378:metabolism*; D002460:Cell Line; D003600:Cytosol / Q000201:enzymology; D018076:DNA, Complementary / Q000235:genetics*; D005260:Female; D015870:Gene Expression; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D008297:Male; D011804:Quinolines / Q000378:metabolism*; D011810:Quinoxalines / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013451:Sulfonic Acids / Q000378:metabolism
D018076:DNA, Complementary; D011804:Quinolines; D011810:Quinoxalines; D013451:Sulfonic Acids; C029216:2-amino-3-methylimidazo(4,5-f)quinoline; C036990:2-amino-3,8-dimethylimidazo(4,5-f)quinoxaline; C005741:sulfamic acid; D015239:Arylsulfotransferase