Bismuth protein binding

While the mechanism of the interaction of these carboxylate complexes with the biological molecules that leads to their activity is not well understood, there is some evidence that the molecules can bind to N-donor and S-donor molecules in proteins. Bismuth(III) has been shown to bind most strongly to the thiolates in glutathione. There is some evidence that Bi(III) can replace metals such as Fe(III) in lactoferrin and transferrin or Zn(II) in metallothionein. ... 

Jadwiga a, Szymansk a and Zelazowski AJ (1979) Induced synthesis of chromochdatin, the low molecular weight bismuth-binding protein in rat kidneys. Chem-Biol Interact 26 139-146. 

Everyone has probably used some Pepto-Bismol at one time or other (this is more common in the United States than in the other parts of the world). The active ingredient is based on a bismuth metal center. It is taken to alleviate upset stomachs. If you consume large quantities your tongue turns black due to the formation of bismuth sulfide — it binds to the sulfur from proteins in the body (and on the tongue) bismuth sulfide is a black material. 

Outside the working environment, the main sources of bismuth are fix>m medicinal preparations and, in some areas, drinking water. Bismuth compounds are generally not well absorbed by the body, but once absorbed, bismuth binds to plasma proteins and concentrates in the kidneys, liver and skin. Bismuth can displace bound lead resulting in the release of lead into the circulatory system. 

J. Bismuth, A. Anselmet and J. Torresani. Triiodothyronine nuclear receptor and the role of non-histone protein factors in in vitro triiodothyronine binding. Biochim. Biophys. Acta 840 271-279 (1985). 

The in vitro interactions of the cysteine-rich intracellular protein Zn7-metal-lothionein with cisplatin and transplatin and the histidine-rich proteins Hpni32,i33 HspA with a bismuth antiulcer compound were investigated, respectively. These kinds of interactions may play a crucial role in the metabolism of various metallodrugs. Notably, drug binding to plasma proteins has a strong influence on their biodistribution, biotransformation, and pharmacokinetics, and therefore merits further characterizations. 

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