The natural substrate for this enzyme may be peptidyl-tRNAs which drop off the ribosome during protein synthesis. Hydrolyzes peptidyl-tRNAs and N-blocked aminoacyl-tRNAs but does not hydrolyze unblocked aminoacyl-tRNAs in vitro. an N-acyl-L-alpha-aminoacyl-tRNA + H2O = a tRNA + an N-acyl-L-amino acid + H(+) Optimum pH is 7.0. Monomer. Belongs to the PTH family.