EVIDENCE FOR ARYLAMINE N-ACETYLTRANSFERASE IN THE NEMATODE ANISAKIS SIMPLEX

N-Acetyltransferase activities with p-aminobenzoic acid and 2-aminoflu orene were determined in Anisakis simplex, a nematode found in the int estine of the salt water fish Trichiurus lepturus. The N-acetyltransfe rase activity was determined using an acetyl CoA recycling assay and h igh pressure liquid chromatography. The N-acetyltransferase activity f rom a number of Anisakis simplex whole tissue homogenizations was foun d to be 2.89 +/- 0.52 nmol/min per mg for 2-aminofluorene and 2.54 +/- 0.45 nmol/min per mg for p-aminobenzoic acid. The K-m and V-max value s obtained were 1.06 +/- 0.69 mM and 9.34 +/- 1.94 nmol/min per mg for 2-aminofluorene, and 2.25 +/- 0.10 mM and 14.44 +/- 0.7 nmol/min per mg for p-aminobenzoic acid, The optimal pH value for the enzyme activi ty was pH 8.0 for both substrates tested. The optimal temperature for enzyme activity was 37 degrees C for both substrates. The N-acetyltran sferase activity was inhibited by iodoacetamide: at 0.25 mM iodoacetam ide, activity was reduced 50% and 1.0 mM iodoacetamide inhibits activi ty more than 90%. Among a series of divalent cations and salts, Cu2+ a nd Zn2+ were demonstrated to be the most potent inhibitors. This is th e first demonstration of acetyl CoA/arylamine N-acetyltransferase acti vity in a nematode and extends the number of phyla in which this activ ity has been found.