Acetyltransferase and sulfotransferase which activate mutagens and carcinogens through O-esterification mechanisms

The regulatory mechanism of acetyltransferase and sulfotransferase, which are involved in the activation of carcinogenic arylamines and their N-hydroxy derivatives, has been studied. Cytosolic N-acetylation of 2-aminofluorene (2-AF) in hamster liver and skin showed tri-modal distribution in the presence of acetyl CoA, whereas no clear segregation was detected in the N-hydroxyarylacetamide-supported N-acetylation and acetyl CoA-dependent O-acetylation of N-hydroxy-Glu-P-1. From hamster livers, two forms of acetyltransferase, AT-I and AT-II, were purified and characterized to have different catalytic and chemical properties. AT-I was detectable in all the hamsters examined, but AT-II was detected only in the animals showing high rates of 2-AF N-acetylation. Cross-matings of the intra- and inter-phenotypes of three different acetylators (rapid, intermediate, and slow) indicate the genetic inheritance of the arylamine N-acetylation, which follows a Mendelian co-dominant trait. Cytosolic sulfotransferase catalyzes the activation of N-hydroxyarylamines and N-hydroxyarylacetamides through the enzymatic O-sulfonylation. The reaction often shows a sex-related difference in rats. Among three sulfotransferases isolated (HAST I, II, and PST I), the level of HASTs was correlated with the 3'-phosphoadenosine 5'-phosphosulfate (PAPS)-dependent activating capacity of N-hydroxy-2-acetylaminofluorene (N-hydroxy-AAF) in rat livers. In addition, hepatic content of HASTs was decreased by hypophysectomy and restored by the intermittent administration of growth hormone, which mimics the male secretory profile. These results indicate that the sex-related difference in secretory profile of pituitary growth hormone is a major determinant of the male-dominant sulfation in this species.(ABSTRACT TRUNCATED AT 250 WORDS)