The natural substrate for this enzyme may be peptidyl-tRNAs which drop off the ribosome during protein synthesis. an N-acyl-L-alpha-aminoacyl-tRNA + H2O = a tRNA + an N-acyl-L-amino acid + H(+) Monomer. Belongs to the PTH family. The predicted gene has been split into 2 genes: At1g18440 and At1g18450.