Plays an important role in deacetylating mercapturic acids in kidney proximal tubules. Also acts on N-acetyl-aromatic amino acids. an N-acyl-aromatic L-alpha-amino acid + H2O = a carboxylate + an aromatic L-alpha-amino acid an N-acetyl-L-cysteine-S-conjugate + H2O = acetate + an S-substituted L-cysteine Binds 1 zinc ion per subunit. Optimum pH is 7.5 with S-benzyl-N-acetyl-L-cysteine as substrate, 7.6 with N-acetyl-L-histidine as substrate, 7.6 with N-acetyl-L-tyrosine as substrate, and 7.7 with N-acetyl-L-phenylalanine as substrate. Exists as a mixture of homodimers and homotetramer, both catalytically active. Predominantly localized in the apical membrane of cells in the S1 segment. In the proximal straight tubules (S2 and S3 segments) is expressed diffusely throughout the cytoplasm. Expressed predominantly in kidney and to a lesser extent in liver. Weakly expressed in heart, small intestine, brain, lung, testis, and stomach. Belongs to the AspA/AstE family. Aspartoacylase subfamily.