Peptide Deformylase

Abstract

Peptide deformylase (EC 3.5.1.31) is a mononuclear iron enzyme that cleaves the formyl group of the N ‐terminal formyl‐methionine residue of nascent polypeptide chains in eubacteria. It is strictly stereospecific for a L ‐amino acid as the first residue of formyl‐peptide substrates and strongly prefers substrates with at least two or more residues. The native enzyme from Escherichia coli is a monomeric protein of 168 amino acid residues that contains one tightly bound Fe 2+ ion. The metal ion is tetrahedrally coordinated by a water molecule and the side chains of residues Cys90, His132, and His136. Similar to thermolysin, the two histidines are part of the HEXXH motif and the glutamate residue is required for enzymatic activity. The native iron form of peptide deformylase is extremely sensitive to oxidative destruction. On substitution of the iron ion by Ni 2+ or Co 2+ the enzyme is insensitive to oxidation and maintains its activity, whereas the Zn 2+ form is nearly inactive.