Metal complexes of amino acids and amino acid side chain groups. Structures and properties

Abstract

Alpha-amino acid residues exhibit various functions in biological systems. The side chain groups are very important for formation of the metal center and its catalytic action in proteins. They are involved in metal binding, molecular recognition by weak interactions, enzyme catalysis, and formation of the molecular environment. This perspective focuses on recent studies on characterization of metal-amino acid complexes involving imidazole, phenol, indole, or alkyl groups, their reactivities, and some selected metal-side chain group interactions.

Stability and Structure of Mixed‐Ligand Metal Ion Complexes That Contain Ni2+, Cu2+, or Zn2+, and Histamine, as well as Adenosine 5′‐Triphosphate (ATP4−) or Uridine 5′‐Triphosphate (UTP4−): An Intricate Network of Equilibria

“…[85] In this context it is worthwhile to recall that, for example, in a fern plastocyanin an imidazole-phenyl (histidine/phenyl-A C H T U N G T R E N N U N G alanine) stack was observed. [7,8] iv) Another remarkable (though indirect) observation is the fact that the N7ÀM 2 + bond present in the binary MA C H T U N G T R E N N U N G (ATP) 2À macrochelates is broken upon formation of mixed ligand complexes as follows from the internal validity of the data in Section 2.4 (Table 4). This conclusion is in accord with the previous results summarized in Section 2.3, that is, the release of N7 in MA C H T U N G T R E N N U N G (ATP) 2À complexes by the coordination of, for example, OH À or NH 3 , as shown by using NMR spectroscopy.…”

“…The following four of these are also of relevance for enzymes and ribozymes: [2][3][4][5] i) The metal ion has a structural role and is instrumental for the three-dimensional shape of the protein or the nucleic acid; ii) the metal ion has a functional role and is binding to the biological target, that is, to the active site in the protein or RNA; iii) the metal ion is a carrier for the active ligands, that is, the substrates; and iv) the metal ion itself is the active catalyst. Especially, but not only, point i) is often connected with further noncovalent interactions, [3,[6][7][8] among which hydrophobic and/or pstacking interactions are especially prominent. [6,9,10] This view is also supported by the p-stacks of histidine-phenyl-A C H T U N G T R E N N U N G alanine (imidazole-phenyl) in a fern plastocyanine, [7,8] by the tryptophan-tryptophan (indole-indole) interactions in Trpzip b hairpin formation [11] or by model studies [12][13][14] including a Cu II -metallocyclophane probe for guanosine 5'-monophosphate in which p-stacking between the anthracene moieties and the guanine residue occurs.…”

“…Especially, but not only, point i) is often connected with further noncovalent interactions, [3,[6][7][8] among which hydrophobic and/or pstacking interactions are especially prominent. [6,9,10] This view is also supported by the p-stacks of histidine-phenyl-A C H T U N G T R E N N U N G alanine (imidazole-phenyl) in a fern plastocyanine, [7,8] by the tryptophan-tryptophan (indole-indole) interactions in Trpzip b hairpin formation [11] or by model studies [12][13][14] including a Cu II -metallocyclophane probe for guanosine 5'-monophosphate in which p-stacking between the anthracene moieties and the guanine residue occurs. [15] It is becoming more and more evident that large nucleic acids like ribozymes [4,[16][17][18] and riboswitches [19] change their three-dimensional structure upon binding metal ions, metal ion complexes, or other small metabolites.…”

Properties of the indole ring in metal complexes. A comparison with the phenol ring

“…Stacking interaction in ternary complexes containing an α-amino acid with the aromatic side chain residue α-Amino acids coordinate to transition metal ions such as Cu(II) and Pd(II) as bidentate ligands through the amino and carboxylate groups, forming a five-membered N,O-chelate ring [31,32]. Their side chain may have an influence on the properties of the complexes.…”

Hydrothermal Synthesis of Cerium Oxide Nanoassemblies through Coordination Programming with Amino Acids

“…5 We showed that carboxylic acids are attached on the {100} surfaces of CeO 2 nanocrystals by coordination bonds and were able to control their size and shape. 4 Along with carboxylic acids, amino acids have been reported to react with metal ions, act as ligands to form complexes, 6,7 and bind to the surface of crystals. 8 Zhang et al 9 and Mitchell et al 10 reported the influence of amino acids on the hydrothermal reaction to control the nanoarchitecture of mesoporous CeO 2 .…”