Peptides metal coordination

McAlister, G.C. Kiessel, S.E.B. Coon, J.J. In vacuo formation of peptide-metal coordination complexes. Int. J. Mass Spectrom. 2008, 276, 149-152. 

Dithiol melanotropin peptide cyclized via rhenium metal coordination PDB ID IBOQ... 

Whilst metal-N(peptide) bond formation inhibits hydrolysis of the peptide bond, coordination to O(peptide) has the opposite effect. These differences in reactivity can be readily demonstrated and put to practical use with the inert Co111 complexes. One of the first examples was the reaction of [Co(trien)(H20)(OH)]2+ with peptides to give hydrolysis of the peptide bond at the N-terminal end. The proposed mechanism involving nucleophilic attack by hydroxide at the peptide carbon is shown in Scheme 7.110 Similar selective hydrolyses of N-terminal peptide bonds have since been demonstrated with other Co111 amine complexes and the reaction has been examined as a method for determining the N-terminal amino acid residue in peptides and proteins.1"112... 

Coordinated a-amino amides can be formed by the nucleophilic addition of amines to coordinated a-amino esters (see Chapter 7.4). This reaction forms the basis of attempts to use suitable metal coordination to promote peptide synthesis. Again, studies have been carried out using coordination of several metals and an interesting early example is amide formation on an amino acid imine complex of magnesium (equation 75).355 However, cobalt(III) complexes, because of their high kinetic stability, have received most serious investigation. These studies have been closely associated with those previously described for the hydrolysis of esters, amides and peptides. Whereas hydrolysis is observed when reactions are carried out in water, reactions in dimethyl-formamide or dimethyl sulfoxide result in peptide bond formation. These comparative results are illustrated in Scheme 91.356-358 The key intermediate (126) has also been reacted with dipeptide... 

In this chapter selected examples from our group are discussed to show how metal coordination to ligand-modified amino acids or peptides can be used for induction or fixing of defined conformations in amino acid residues or di- and tripeptides. In this context Ramachandrarfs method for conformational analysis of peptide or protein structures will be introduced. 

Approaches Used to Stabilize Bioactive Conformations at Peptides by Metal Coordination I 41... 

Protein-protein interactions usually occur on the surface of proteins where mainly loops or turns are present [24], It is, therefore, of interest to stabilize specific peptide turns and test them for their biological activity [25-28], As discussed, metal coordination seems to be a powerful tool for obtaining macrocycles with a bent peptidic domain simply by mixing metal ions and peptide-bridged ligands. 

The stabilization of well-defined peptide microstructures is an important challenge in bioorganic chemistry. As the presented results show, metal coordination can be a simple but very effective tool for reaching this goal and fixing three dimensional molecular structures. The conformational (and stereochemical) information which is embedded in configurationally stable metal complex units can be transferred to amino acid residues or even to relatively large peptides and can induce helical-, sheet- or as discussed turn-type structures. 

Nucleic Acid Metal Ion Interactions Nutritional Aspects of Metals Trace Elements Peptide-Metal Interactions Zinc Enzymes Zinc Inorganic Coordination Chemistry. 

Figure 12 Schematic of a structural zrac-biudiug site that provides active-site residues from amino acids located within the metal-coordination spacers. Other active-site residues are often provided hy the peptide sequence N-terminal to the structural zinc site. The symbol Y can represent more than one amino acid. (Table 4)...

IR analysis confirmed the existence of peptides bound to the nanocluster surface. Vibrations attributed to the histidine side chains as well as from the amide stretches were present in the purified nanocluster spectra. Also, a loss of the N-H stretching band of histidine was noted, indicating a coordination mode for the peptide-metal nanostructures. This analysis confirmed the attachment of the HRE peptide to the surface. 

Cobalt Inorganic Coordination Chemistry Copper Inorganic Coordination Chemistry Copper Proteins Oxidases Copper Proteins with Dinuclear Active Sites Copper Proteins with Type 2 Sites Cytochrome Oxidase Iron Heme Proteins, Peroxidases, Catalases Catalase-peroxidases Iron Proteins with Mononuclear Active Sites Metal Ion Toxicity Metal-related Diseases of Genetic Origin Metallocenter Biosynthesis Assembly Metalloregulation Peptide Metal Interactions Zinc Enzymes. 

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