Peptide deformylase (LiPDF). a target protein for antibacterial agents from pathogenic bacteria Leptospira interrogans was identified and purified. Enzymatic studies including kinetics and inhibition revealed new inspiring highlights. The purified active enzyme was a dimer and showed a hyperbolic progress plot when the substrate was low but an excess substrate inhibition effect in higher substrate concentration. Variants on the metal-binding ligand-Cys 102 were constructed to verify the indispensable attribute. Also the variant. LiPDF with the insertion residues (R(70)Y(71)P(72)G(73)T(74)P(75)D(76)V(77)) between the conserved motif 1 and motif 2 excised, was constructed and displayed no marked changes on enzymatic features. The results of atom absorbance proved that it contains a tightly bound Zn2+ rather than Fe2- in E coliPDF that is an essential cofactor for its high catalytic activity, (C) 2002 Elsevier Science (USA). All rights reserved.