BAPTA (1,2-bis(''o''- amino phenoxy)

ethane Ethane ( , ) is a naturally occurring Organic compound, organic chemical compound with chemical formula . At standard temperature and pressure, ethane is a colorless, odorless gas. Like many hydrocarbons, ethane is List of purification methods ...

-''N'',''N'',''N′'',''N′''-tetra acetic acid) is an

aminopolycarboxylic acid left, 120px, a metal complex with the EDTA anion 120px, Aspartic acid is an aminodicarboxylic acid and precursor to other ligands. An aminopolycarboxylic acid (sometimes abbreviated APCA) is a chemical compound containing one or more nitrogen at ...

with a high affinity for

calcium Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to it ...

. It is a white solid. It is used in research to chelate Ca²⁺, as it behaves similarly to EGTA and

EDTA Ethylenediaminetetraacetic acid (EDTA), also called EDTA acid, is an aminopolycarboxylic acid with the formula . This white, slightly water-soluble solid is widely used to bind to iron (Fe2+/Fe3+) and calcium ions (Ca2+), forming water-solubl ...

Complexation

BAPTA, as its

conjugate base A conjugate acid, within the Brønsted–Lowry acid–base theory, is a chemical compound formed when an acid gives a proton () to a base—in other words, it is a base with a hydrogen ion added to it, as it loses a hydrogen ion in the reve ...

, binds calcium ions as a decadentate ligand: : According to

X-ray crystallography X-ray crystallography is the experimental science of determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Diffraction, diffract in specific directions. By measuring th ...

. the four

carboxylates In organic chemistry, a carboxylate is the conjugate base of a carboxylic acid, (or ). It is an anion, an ion with negative charge. Carboxylate salts are salts that have the general formula , where M is a metal and ''n'' is 1, 2,.... ...

, two

amine In chemistry, amines (, ) are organic compounds that contain carbon-nitrogen bonds. Amines are formed when one or more hydrogen atoms in ammonia are replaced by alkyl or aryl groups. The nitrogen atom in an amine possesses a lone pair of elec ...

s, and two ether oxygens bind to Ca²⁺. There is a range of reported values for the dissociation constant of BAPTA, though 0.2 μM appears consistently. The rate constant for calcium binding is 500 μM⁻¹ s⁻¹. The complexation process of calcium ion to BAPTA can be deconvoluted into three main processes: conformational changes of the glicol linker, nitrogen conjugation and electronic effects changes of the benzene rings. BAPTA is a component of some fluorescent calcium ion indicators such as Calcium Green and Oregon Green 488 BAPTA-1 and -2 (OGB-1, OGB2). These indicators change their fluorescence intensity and fluorescence lifetime depending on the calcium ion concentration.

References

{{DEFAULTSORT:Bapta Anilines Carboxylic acids Chelating agents Phenol ethers Glycol ethers

Complexation

See also

References