The localization and some properties of the N-deacetylase of Ascaris lumbricoides var suum.

1. Hydrolysis of acetanilide by the nematode Ascaris lumbricoides var suum occurred in the cytosol of the intestinal epithelium and to a lesser degree in the cytosol of the reproductive organs. Cuticle and mesenchyme fluid showed no measurable activity. 2. The molecular weight of the enzyme responsible for hydrolysis was estimated to be about 90 000. 3. Hydrolysis of N-acetyl compounds occurred optimally at pH 7-4 at 30-35 degrees and at a substrate concentration of 10(-2) M. 4. The reaction was inhibited 50% by Cu2+, Zn2+, n-ethylmaleimide or p-chloromercuribenzoate at 10(-4) M. The anthelmintic organophosphates inhibited N-deacetylation by 50% at 10(-7) M. Dithiothreitol enhanced the reaction rate but glutathione and thioglycollic acid were without effect.