A study of the amino-acid complexes formed by metals of Group II of the periodic classification

Abstract

The stability constants of some complexes of alpha-amino acids with metals of Group II of the periodic-classification were measured by a potentiometric method. The predominant part played by the metal in determining the stability constant was confirmed. Metals of Group IIa formed complexes with stability constants too low to be measured. Group IIb metal complexes yielded measurable constants in the order of magnitude Hg > Be > Zn > Cd. The results of a number of investigators using a range of metals with glycine, alpha-alanine and glycylglycine were compared. The effect of substituting the hydrogen atoms of the amino group of glycine on stability constants was studied. The only appreciable structural effect observed was the decrease in stability produced by peptide formation. Increase of chain length resulted in decreased stabilities.