Contains Zn2+. The enzyme is found in animals and is involved in the hydrolysis of N-acylated or N-acetylated amino acids (except L-aspartate). It acts on mercapturic acids (S-conjugates of N-acetyl-L-cysteine) and neutral aliphatic N-acyl-alpha-amino acids. Some bacterial aminoacylases demonstrate substrate specificity of both EC 22.214.171.124 and EC 126.96.36.199. cf. EC 188.8.131.52, aspartoacylase and EC 184.108.40.206, N-acyl-aromatic-L-amino acid amidohydrolase.