Glycine-Metal Binding

The binding process between the glycine molecule and some metal cations in the gas phase has been investigated. It has been shown that the metal cations can bind the glycine molecule in several ways, and many stationary points can be found in 

In all the previous cases, a general agreement between our calculations and literature results was always found, at least at a qualitative level. With the Zn ion, the situation is more involved, owing to the presence of the d orbitals, which lead to 

It can be observed that both the dimension of the space of the valence functions and the use of pseudopotentials affect the relative stabilities of the two conform-ers. With triple and quadruple basis sets, the zwitterionic form is more stable than the charge-solvated one, whereas with the SNSD (double-Q basis, the stability order is inverted. Furthermore, use of a pseudopotential for describing core electrons seems to increase the stability of the CSl structure, as shown by corn-parson between the AVTZ and AVTZ-PP and between the AVQZ and AVQZ-PP calculations. The effect of the method seems to be smaller than the effect of the basis set on the overall energetics. 

NBO Analysis In order to gain a deeper understanding of the bonding character of the complexes, an NBO analysis has been for all the structures. 

Considering the most relevant spectrum features for a set of metal complexes. Table 10.7 reports the harmonic and anharmonic (GVPT2 and HDCPT2) frequencies related to the C=0 stretching mode. The strong redshift of such frequencies along the series of the cations can be observed, suggesting that as 

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Steffens, J.C., Hunt, D.F. Williams, B.G. (1986). Accumulation of non-protein metal-binding polypeptides (gamma-glutamyl-cysteinyl) -glycine in selected cadmium-resistant tomato cells. Journal of Biochemistry 261, 13879-82. 

Previous studies have reported silver staining with other amino acids. Heukeshoven and Dernick reported silver staining of the homopolymers of glycine, serine, proline and aspartic acid (4 ) while Nielsen and Brown reported the formation of colored silver complexes with aspartate, and tyrosine (45,). Staining of these homopolymers was not observed in the study of Merril and Pratt (32,), and prior metal binding studies failed to demonstrate metal interactions with the side-chain hydroxyl groups of serine, threonine or tyrosine... 

The comparison of the primary sequences of Dx with those of several Rds, for which three-dimensional structures are available, (Figure 20-3), shows that the only conserved residues are the four cysteines involved in metal binding, the two glycines which precede Cys 12 and Cys 29, and Tyr 7 (the single aromatic residue present in the Dx amino add sequence). Additionally, Dx has a deletion of several amino add... 

The amino-terminal end of the prion protein is rich in histidine and glycine residues, and is believed to be the metal-binding site of the protein. Specifically, the mammalian prion protein... 

Stability constants (ethylendiamine, glycinate, oxalate), surface complex formation constants and solubility products (sulfides) of transition ions. The surface complex formation constant is for the binding of metal ions to hydrous ferric oxide =Fe-OH + Me2+ =FeOMe++ H+ K. ... 

Glycine A-methyltransferase is also reported to have an ordered binding mechanism with SAM binding first to the enzyme, there being no metal-ion dependency. Cooperative behavior is observed with SAM binding. The cooperative nature can be eliminated by the tryptic hydrolysis of the N-terminal eight amino acid residues. 

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