Chelation of some bivalent metal ions by racemic and enantiomeric forms oftyrosine and tryptophan

Abstract

Equlibrium constants are reported for the stepwise dissociation of protons from D-, L-, and DL-tyrosine and D-, L-, and DL-tryptophan, and the stepwise interaction of their ligand anions with Cd(II), Cu(II), Ni(II), Pb(II), and Zn(II) in aqueous solution at 20° and an ionic strength of 0.37 (NaNO 3). No differences have been observed either between the proton dissociation constants of the isometric forms of ligands or between the stability contants of the respective complex species (MD and ML, or MD 2, ML 2 and MLD).