Amino acids ligands

In biological systems metals and metalloids not only interact with high molecular mass constituents, for example proteins and DNA, but also with a host of low molecular mass ligands, amino acids, peptides, inorganic ligands and others. The above discussion also apply to these species. A fraction of some elements are unbound and these could be treated as hydrated free ions. 

They further observed the stereoselective effect in several other systems containing other amino acids as the polymer ligands74, and identified certain prerequisites for effective resolution (i) mixed complexes are more stable and it is better to use Cu(II) or Ni(II), (ii) the sum of the dentation of the polymer ligands and the mobile ligands (amino acids) should be equal to the coordination number of the central metal ion. The difference in free energy of formation of the two dia-stereomeric complexes with L- and D-proline was estimated to be 0.4 to 0.5 kcal/mol for the L-proline-Cu resin. It was emphasized that the stereoselectivity of this process was sufficient for the complete resolution of racemic a-amino acids74. ... 

Ni", Cu11 mixed-ligand amino-acid compounds 904... 

EPR measurements have shown that this Cu2+ is coordinated at least in part to nitrogen atoms of the protein. Nothing is known about the liganding amino acids. 

The chiral molecular recognition manifested in copper(II) simple and mixed complexes with biofunctional ligands (amino acids, dipepti s, etc..) was found to be strongly dependent on the formation of weak bonds between side chain residues [21,22], as shown in Figure 2. 

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