The formation microequilibria of the proton, calcium and magnesium complexes of γ-carboxyglutamic acid (GLA) and some related compounds were studied via pH-metric titration. The inductive effects of differently protonated or protected donor groups are discussed. The distribution curves of the differently protonated microspecies and the probabilities of the different protonation pathways are presented. The formation constants of differently protonated metal complexes are given. The calcium ion binding constants for N-acetyl-γ-carboxyglutamic acid α-methylamide (which functionally models a single GLA in polypeptide chains) was found to be greater than that for GLA, but much smaller than that for the natural GLA-containing polypeptides.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry