The Kinetics of Combination of Carbon Dioxide with the Anions of Glycine, Glycyl-Glycine, and Related Amino Acids

The velocity constants k' of the reaction of carbon dioxide with the anions of the amino acids glycine, glycyl-glycine, α-alanine, β-alanine, valine, histidine, β-phenyl alanine, α-amino phenyl acetic acid, and e-amino caproic acid have been determined by the rapid thermal method. At 25 °C the value of k' is given approximately by the equation log10k' = 0.262 pK + 1.197 where pK is the pK value of the amino group which reacts. For glycine and glycyl-glycine the energies of activation have been determined as 8.2 and 8.3 kcal respectively over the range 10 to 40 °C.