Species of rare earth (III), calcium (II) and zinc (II) in the presence of L-histidine and L-typtophane

Rare earth(III)-histidine (His)- tryptophane (Trp). Ca(II)-His-Trp and Zn(II)-His-Trp systems were studied by potentiometric titration and computer simulation under physiological conditions. The species of the systems and their stability constants were determined. The distributions of species of rare earth(III), Ca(II) and Zn(II) were discussed.