Amination of tyrosine in liver cytosol protein of male F344 rats treated with 2-nitropropane, 2-nitrobutane, 3-nitropentane, or acetoxime.
Previously, the secondary nitroalkane 2-nitropropane, a strong hepatocarcinogen in rats, had been shown to induce the formation of 8-aminoguanine in both DNA and RNA of rat liver through a sulfotransferase-mediated pathway. This pathway was postulated to convert the carcinogen into an aminating species [Sodum, R. S., et al. (1994) Chem. Res. Toxicol. 7, 344-351]. To submit this postulate to further test, we examined liver proteins of rats treated with 2-nitropropane, other carcinogenic secondary nitroalkanes, or the related rat liver tumorigen acetoxime for the presence of 3-aminotyrosine, the expected product of tyrosine amination. Using ion-pair and/or cation-exchange high-performance liquid chromatography with electrochemical detection, we found that the liver cytosolic proteins of these animals contained 0.1-1.5 mol of 3-aminotyrosine/10(3) mol of tyrosine. Treatment with the noncarcinogenic primary nitroalkane 1-nitropropane or with other primary nitroalkanes did not produce an analogous increase in the aminated amino acid (level of detection estimated at approximately 0.01 mol/10(3) mol of tyrosine). To our knowledge, this is the first report of the modification of protein tyrosine in vivo by a carcinogen. In vitro studies with acetoxime-O-sulfonate and hydroxylamine-O-sulfonate showed that these proposed intermediates in the activation pathway of 2-nitropropane react with guanosine to give 8-aminoguanosine, N1-aminoguanosine, and 8-oxoguanosine and also react with tyrosine to give 3-aminotyrosine and 3-hydroxytyrosine. The in vitro amination and oxidation of guanosine at C8 were also produced by acetophenoxime-O-sulfonate and 2-heptanoxime-O-sulfonate. These results provide additional evidence for the production of a reactive species capable of aminating nucleic acids and proteins from 2-nitropropane and other carcinogenic secondary nitroalkanes by a pathway involving oxime- and hydroxylamine-O-sulfonates as intermediates.
Sodum
R S
RS
Division of Biochemical Pharmacology, American Health Foundation, Valhalla, New York 10595, USA.
Fiala
E S
ES
D000473:Alkanes / Q000494:pharmacology; D000586:Amination; D000818:Animals; D002073:Butanes; D002273:Carcinogens / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D003600:Cytosol / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D009595:Nitroparaffins / Q000494:pharmacology*; D010091:Oximes / Q000494:pharmacology*; D011407:Propane / Q000031:analogs & derivatives / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014443:Tyrosine / Q000031:analogs & derivatives / Q000032:analysis / Q000378:metabolism*
D000473:Alkanes; D002073:Butanes; D002273:Carcinogens; D009595:Nitroparaffins; D010091:Oximes; C019253:3-aminotyrosine; C110359:3-Nitropentane; D014443:Tyrosine; C110358:2-Nitrobutane; C016617:2-nitropropane; C035911:acetoxime; D011407:Propane