Do cells have chelating agents?

Question

Do cells have chelating agents?

Answer 1

Virtually all biochemicals exhibit the ability to dissolve metal cations. Thus proteins, polysaccharides, and polynucleic acids are excellent polydentate ligands for many of the metal ions. In addition to these adventitious chelators, several are produced to specifically bind certain metals. Histidine, malate and phytochelatin are typical chelators used by plants.

Virtually all metalloenzymes feature metals that are chelated, usually to peptides or cofactors and prosthetic groups. Such chelating agents include the porphyrin rings in hemoglobin and chlorophyll. Many microbial species produce water-soluble pigments that serve as chelating agents, termed siderophores. For example, among species of Pseudomonas, they are known to secrete pycocyanin and pyoverdin that bind iron. Enterobactin, produced by E. coli, is the strongest chelating agent known

http://en.wikipedia.org/wiki/Chelation