EGTA (chemical)

Chembox new
ImageFile = egta.png ImageSize =
IUPACName = glycol-bis(2-aminoethylether)-N,N,N',N'-tetraacetic acid
OtherNames =
Section1 = Chembox Identifiers
CASNo = 67-42-5
PubChem =
SMILES =
Section2 = Chembox Properties
Formula = C₁₄H₂₄N₂O₁₀
MolarMass = 380.35 g/mol
Appearance =
Density =
MeltingPtC = 241
BoilingPt =
Solubility =
Section3 = Chembox Hazards
MainHazards =
FlashPt =
Autoignition =

EGTA is the chemical compound ethylene glycol tetraacetic acid, a chelating agent that is related to the better known EDTA, but with a much higher affinity for calcium than for magnesium ions. It is useful for making buffer solutions that resemble the environment inside living cells, where calcium ions are usually at least a thousandfold less concentrated than magnesium.

The pKa for binding of calcium ions by tetrabasic EGTA is 11.00, but the protonated forms do not significantly contribute to binding, so at pH 7, the apparent pKa becomes 6.91. See Qin "et al." for an example of a pKa calculation. [cite journal | title = Ca²⁺-induced inhibition of the cardiac Ca²⁺ channel depends on calmodulin | journal = PNAS | volume = 96 | issue = 5 | pages = 2435–2438 | month = March | year = 1999 | url = http://www.pnas.org/cgi/content/full/96/5/2435 | accessdate = 2007-10-22 | author = Ning Qin, Riccardo Olcese, Michael Bransby, Tony Lin, and Lutz Birnbaumer | pmid = 10051660 | doi = 10.1073/pnas.96.5.2435]

EGTA has also been used experimentally for the treatment of animals with cerium poisoning and for the separation of thorium from the mineral monazite. EGTA is used as a compound in elution buffer in the protein purification technique known as Tandem Affinity Purification (TAP), in which recombinant fusion proteins are bound to calmodulin beads and eluted out by adding EGTA.

EGTA is often employed in Dentistry, more specifically Endodontics in the removal of smear layer.

See also

* EDTA
* BAPTA

References