CADMIUM, COPPER AND ZINC-COMPLEXES OF POLY-L-CYSTEINE

The metal complexes of poly-L-cysteine (PLC) were evaluated for their potential use in trace metal preconcentration and separation, Formation constants (log K) for the Cd2+ and Zn2+ complexes of PLC estimated by spectrophotometric titration were 8.0 +/- 0.8 and 9.5 +/- 0.5, respectively, The PLC sulfhydryl groups were most likely oxidized to disulfides by CU2+, and binding of Cu+ with the molecule was expected, The moles of metal bound by PLC reflecting its strongest sites relative to a stable competing ligand for CU2+ and Zn2+ mere 1.4 and 0.40 mmol g(-1) of PLC, respectively. The presence of Na+ (29 mmol l(-1)) or Ca2+ (0.5 mmol l(-1)) had no measurable effect on the amount of Zn-PLC complex formed.