The natural substrate for this enzyme may be peptidyl-tRNAs which drop off the ribosome during protein synthesis. Involved in lambda inhibition of host protein synthesis. PTH activity may, directly or indirectly, be the target for lambda bar RNA leading to rap cell death (By similarity). an N-acyl-L-alpha-aminoacyl-tRNA + H2O = a tRNA + an N-acyl-L-amino acid + H(+) Monomer. Belongs to the PTH family.