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Chelation
The binding of metal cations (metal atoms or
molecules possessing a positive electrical charge) by
atoms possessing unshared electrons (thus the
electrons can be "donated" to a bond with a cation).
The binding of the metal (cation) to the
(electron-excess) chelator atom (ligand) results in
formation of
a chelator/metal cation complex. The intra-atom bonds
thus formed are given the name of coordination bonds.
The properties of the chelator/metal cation complex
frequently differ markedly from the "parent" cation.
Both carboxylate and amino (molecular) groups readily
bind metal cations. One of the most widely used
chelators is EDTA (ethylenediamine tetraacetate). It
has a strong affinity for metal cations possessing two
(bi) or more positive (electrical) charges. Each EDTA
molecule binds one metal cation. The EDTA molecule can
be visualized as a "hand" (having only four fingers)
which grasps the metal cation. Some enzymes (which
require metal cations for their activity) are
inactivated by EDTA (and other chelators) in that the
chelators preferentially remove the metal from the
enzyme.
ION, EDTA, LIGAND (IN BIOCHEMISTRY), CARBOHYDRATES, ENZYME, HEME, CHELATING AGENT, TRANSFERRIN, PHYTATE, LOW-PHYTATE CORN, LOW-PHYTATE SOYBEANS |
