Low-molecular-weight organic ligands

Figure 7 Letkeman (1996) used chemical speciation calculations to estimate the major complexes for lead and mercury as a function of pH in a fluid having overall plasma composition. The results show that most metal complexes with low-molecular-weight organic ligands such as amino acids diminish in importance with decreasing pH (such as in the gastric fluids) due to the increased protonation of the organic ligands. Cl—chloride Cy—cysteinate Ct—citrate Glut— glutathione (reproduced by permission of the Division of Chemical Education Inc. from J. Chem. Educat.

The ligands of interest are those present in ground water, namely, HCOJ, CO3-, SO2-, Cl-, F , OH- and low-molecular weight organic acids. Environmental concentrations of these ions [150] and the procedure for constructing a predominance diagram are given in the literature [151],... 

Figure 6 Chemical speciation calculations have been used (May et al.,l911 May and Williams, 1980) to estimate the dominant low-molecular-weight organic and inorganic complexes for various metals in the plasma. The results show that each metal can he complexed hy a unique set of ligands. Results of such speciation calculations can he used to infer the important chemical complexes and complexing ligands in other body fluids such as extracellular fluids.

Lobel, P.B. and H.D. Marshall. 1988. A unique low molecular weight zinc-binding ligand in the kidney cytosol of the mussel Mytilus edulis, and its relationship to the inherent variability of zinc accumulation in this organism. Mar. Biol. 99 101-105. 

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