Dependence of hydrolytic cleavage of histidine-containing peptides by palladium(II) aqua complexes on the co-ordination modes of the peptides

Reactions of palladium(II) complexes cis-[PdCl 2 (en)] and cis-[PdCl 2 (L-HMet-S,N) ], in which en is ethane-1,2-diamine and methionine is an S,N-bidentate ligand, and their aqua analogs with dipeptides glycyl-L-histidine (Gly-His), L-histidylglycine (His-Gly), and the N-acetylated dipeptides MeCO-Gly-His and MeCO-His-Gly have been studied by 1 H NMR spectroscopy. In the reactions of cis-[PdCl 2 (L-HMet-S,N)] and cis-[PdCl 2 (en)] with Gly-His the formation of [Pd(Gly-His)(L-HMet-S)] + and [PdCl(Gly-His)] occurs at 1.5 < pH < 3.5. Tridentate co-ordination of Gly-His causes release of the en from cis-[PdCl 2 (en)] and ring opening of the L-HMet chelate in cis-[PdCl 2 (L-HMet-S,N) ]. The crystal structure of [PdCl(Gly-His)] shows that the peptide is bound to palladium(II) through imidazole N-3, amide, and amino nitrogen atoms. Tridentate chelation of Gly-His to palladium(II) is unfavorable for the hydrolysis of the peptide. The dipeptide His-Gly co-ordinates to palladium(II) as a bidentate ligand, via the imidazole N-3 and amino nitrogen atoms. This co-ordination mode also is unproductive for the hydrolysis of the peptide. However, at lower pH this complex converts into a hydrolytically active one, in which the dipeptide is bound to palladium(II) via the imidazole N-3 atom only. The dipeptides MeCO-His-Gly and MeCO-Gly-His, in which the terminal amino group is acetylated, exhibit more versatile co-ordination chemistry in the reactions with cis-[PdCl 2 (en)] and cis-[PdCl 2 (L-HMet-S,N)] and form complexes in which the imidazole N-1 atom co-ordinates to palladium(II). These studies with model complexes contribute to the understanding of selective cleavage of peptides and proteins by palladium(II) aqua complexes.

[1]  Richard Wolfenden,et al.  Rates of Uncatalyzed Peptide Bond Hydrolysis in Neutral Solution and the Transition State Affinities of Proteases , 1996 .

[2]  N. Kostić,et al.  Effects of Linkage Isomerism and of Acid−Base Equilibria on Reactivity and Catalytic Turnover in Hydrolytic Cleavage of Histidyl Peptides Coordinated to Palladium(II). Identification of the Active Complex between Palladium(II) and the Histidyl Residue , 1996 .

[3]  N. Kostić,et al.  New Selectivity and Turnover in Peptide Hydrolysis by Metal Complexes. A Palladium(II) Aqua Complex Catalyzes Cleavage of Peptides Next to the Histidine Residue , 1996 .

[4]  L. Qin,et al.  SITE-SPECIFIC HYDROLYTIC CLEAVAGE OF CYTOCHROME C AND OF ITS HEME UNDECAPEPTIDE, PROMOTED BY COORDINATION COMPLEXES OF PALLADIUM(II) , 1994 .

[5]  Long-gen Zhu,et al.  Hydrolytic cleavage of peptides by palladium(II) complexes is enhanced as coordination of peptide nitrogen to palladium(II) is suppressed , 1994 .

[6]  Long-gen Zhu,et al.  Selective hydrolysis of peptides, promoted by palladium aqua complexes : kinetic effects of the leaving group, pH, and inhibitors , 1993 .

[7]  V. Moreno,et al.  Methionine and histidine Pd(II) and Pt(II) complexes: Crystal structures and spectroscopic properties , 1992 .

[8]  Long-gen Zhu,et al.  Toward artificial metallopeptidases: mechanisms by which platinum(II) and palladium(II) complexes promote selective, fast hydrolysis of unactivated amide bonds in peptides , 1992 .

[9]  L. Sayre,et al.  Metal ion catalysis of amide hydrolysis. Very large rate enhancements by copper(II) in the hydrolysis of simple ligand-functionalized tertiary amides , 1992 .

[10]  I. E. Burgeson,et al.  Selective hydrolysis of unactivated peptide bonds, promoted by platinum(II) complexes anchored to amino acid side chains , 1991 .

[11]  R. Eldik,et al.  Rate and equilibrium data for substitution reactions of diaqua(ethylenediamine)palladium(II) with chloride in aqueous solution , 1990 .

[12]  L. Menabue,et al.  Deprotonated amide nitrogen coordinating to the palladium(II) ion. Crystal and molecular structure of disodium bis(N-tosylglycinato-(N,O)palladate(II) , 1990 .

[13]  Helmut Sigel,et al.  Coordinating properties of the amide bond. Stability and structure of metal ion complexes of peptides and related ligands , 1982 .

[14]  R. Martin,et al.  Transition metal ion induced deprotonation of amide hydrogens in sulfhydryl containing compounds , 1981 .

[15]  E. Matczak-Jon,et al.  Proton and carbon-13 NMR studies on coordination of ATP nucleotide to Pd(II)glycyl-L-histidine complex , 1979 .

[16]  Richard J. Sundberg,et al.  Interactions of histidine and other imidazole derivatives with transition metal ions in chemical and biological systems , 1974 .

[17]  R. Martin,et al.  Circular dichroism of copper(II) and palladium(II) complexes of N-methyl-L-amino acids and dipeptides , 1971 .

[18]  R. C. Warren,et al.  The crystal and molecular structure of dichloro-DL-methioninepalladium(II). , 1970, Acta crystallographica. Section B: Structural crystallography and crystal chemistry.

[19]  J. K. Howie,et al.  Proton magnetic resonance studies of amino acid complexes of platinum(II). I. Synthesis, spectral interpretation, and conformational implications , 1968 .