Removes the formyl group from the N-terminal Met of newly synthesized proteins (PubMed:7896716). Requires at least a dipeptide for an efficient rate of reaction. N-terminal L-methionine is a prerequisite for activity but the enzyme has broad specificity at other positions. H2O + N-terminal N-formyl-L-methionyl-[peptide] = formate + N-terminal L-methionyl-[peptide] Upon overproduction is isolated with 1 Fe(2+) ion per monomer, a Ni(2+)-bound form is as active while a Zn(2+)-bound form is inactive (PubMed:9610360). Inhibited by 1,10-phenanthroline. Monomer. Belongs to the polypeptide deformylase family.