Relative silver(I) ion binding energies of α-amino acids: A determination by means of the kinetic method

The relative silver(I) ion binding energies of 19 α -amino acids have been measured by means of the kinetic method. In general, they are similar to the relative copper(I) ion binding energies of corresponding amino acids although there are differences that can be accounted for by differences in silver(I) and copper(I) chemistry. The correlation with proton basicities is comparatively poorer. Again, the differences between silver(I) and proton binding can be attributed to differences in silver(I) and proton chemistry. The relative silver(I) binding energies measured are best described as relative basicities or ΔΔ G Ag ° ’s. The observed internal consistency during construction of a silver(I) ion basicity ladder implies that ΔΔ S Ag ° is approximately zero except when histidine and lysine are involved. For 16 α-amino acids, their relative silver(I) ion basicities ≈ relative silver(I) ion affinities or ΔΔ G ° Ag ≈ ΔΔ H Ag ° .