EVIDENCE FOR ARYLAMINE N-ACETYLTRANSFERASE ACTIVITY IN THE BACTERIUM HELICOBACTER-PYLORI

N-Acetyltransferase activities with p-aminobenzoic acid and 2-aminoflu orene were determined in Helicobacter pylori from gastroduodenal disea se patients. The N-acetyltransferase activity was determined using an acetyl CoA recycling assay and high pressure liquid chromatography. Th e N-acetyltransferase activities from a-number of Helicobacter pylori samples were found to be 0.91 +/- 0.12 nmole/min/mg protein for the ac etylation of 2-aminofluorene and 0.75 +/- 0.22 nmole/min/mg protein fo r the acetylation of p-aminobenzoic acid. The apparent K-m and V-max v alues obtained were 1.10 +/- 0.08 mM and 2.34 +/- 0.14 nmol/min/mg pro tein for 2-aminofluorene, and 0.92 +/- 0.09 mM and 2.08 +/- 0.16 nmol/ min/mg protein for p-aminobenzoic acid. The optimal pH value for the e nzyme activity was 6.0 for both substrates tested. The optimal tempera ture for enzyme activity was 37 degrees C for both substrates. The N-a cetyltransferase activity was inhibited by iodacetamide: at 0.25 mM io dacetamide, activity was reduced 50% and 1.0 mM iodacetamide inhibited activity more than 90%. Among a series of divalent cations and salts, Cu2+ and Zn2+ were demonstrated to be the most potent inhibitors. Amo ng the protease inhibitors, only ethylenediaminetetraacetic acid signi ficantly protected N-acetyltransferase. Iodoacetic acid, in contrast t o the other agents, markedly inhibited N-acetyltransferase. This is th e first demonstration of acetyl CoA:arylamine N-acetyltransferase acti vity in Helicobacter. pylori. (C) 1997 Elsevier Science Ireland Ltd.