Metal Complexes of Marine Peptide Metabolites: A Novel Ag₄ Cluster

Abstract

Silver(I) ions are bound selectively and with high cooperativity to the peptide westiellamide obtained from Lisso‐clinum. The complex contains a unique [Ag4]4+ cluster sandwiched between two neutral macrocyclic ligands (see structure on the right). The importance of metal chelation for the biological activity is currently under investigation.

Cyclic peptide marine metabolites and CuII

“…Initial reasons for investigation included the coordination chemistry of the individual metal ions, understanding the electronic structures, stabilities and selectivity with particular metal ions, and recent efforts have been directed increasingly towards reactivities to elucidate the possible biological functions of these peptides and complexes. 34,[43][44][45][46][47]49,61,67,94,[110][111][112][113] There is a distinct difference between various species with respect to the heterocycles involved in the cyclic peptides, and this must lead to differences in the corresponding transition metal coordination chemistry, specifically also in terms of electronic structures, stabilities and reactivities and therefore might have some influence in the biological activity. The L. bistratum derived macrocycles include oxazoline-based cyclic pseudo-hexapeptides (e.g.…”

“…112 However, the limiting factor in metal ion complexation studies was (and partially still is) the availability of large enough amounts of the metabolites (ligands). In addition, an often not unambiguously solved question is, 47,112 whether the biological activity involves metal ion chelation -what exactly the biological activity is has not yet been studied in detail. Initial quantitative investigations of the interactions of metal ions with a range of patellamides were undertaken using NMR, EPR, UV-vis-NIR and circular dichroism (CD) spectroscopy.…”

Formation of mononuclear and chloro-bridged binuclear copper(II) complexes of patellamide D, a naturally occurring cyclic peptide: influence of anion and solvent

“…The recognition of the potential role of cyclic peptides of marine origin as ionophores in biological systems has prompted a number of studies of the complexation reactions of these peptides with the transition and non-transition elements [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Studies of the metal binding properties of these molecules have been suggested to have important implications regarding the biological activity of these compounds in vivo, [13,17] and one study has suggested that copper(II) is the biologically relevant metal for the patellamides, one class of these peptides [14].…”

Marine metabolites and metal ion chelation. Circular dichroism studies of metal binding to Lissoclinum cyclopeptides

“…macrocyclic cavities, polar functional groups, in chelating arrangements with potential for wrapping around metal ions. 7 We now describe our studies of the binding properties of the lissoclinum cyclopeptides, 3, 4 and 5 (also known as 'patellamides' A, B and E respectively) with zinc() and copper() ions, using circular dichroism (CD) and mathematical modelling techniques. (ii) Do metals provide a template for biological assembly of the metabolites?…”