BAPTA

BAPTA
Names
	Preferred IUPAC name 2,2′,2′′,2′′′-[Ethane-1,2-diylbis(oxy-2,1-phenylenenitrilo)]tetraacetic acid
Identifiers
CAS Number	85233-19-8 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:60888 ;
ChemSpider	94562 ;
ECHA InfoCard	100.157.377
PubChem CID	104751;
UNII	K22DDW77C0 ;
CompTox Dashboard (EPA)	DTXSID30234432 ;
	InChI InChI=1S/C22H24N2O10/c25-19(26)11-23(12-20(27)28)15-5-1-3-7-17(15)33-9-10-34-18-8-4-2-6-16(18)24(13-21(29)30)14-22(31)32/h1-8H,9-14H2,(H,25,26)(H,27,28)(H,29,30)(H,31,32) Key: FTEDXVNDVHYDQW-UHFFFAOYSA-N ; InChI=1/C22H24N2O10/c25-19(26)11-23(12-20(27)28)15-5-1-3-7-17(15)33-9-10-34-18-8-4-2-6-16(18)24(13-21(29)30)14-22(31)32/h1-8H,9-14H2,(H,25,26)(H,27,28)(H,29,30)(H,31,32) Key: FTEDXVNDVHYDQW-UHFFFAOYAD;
	SMILES O=C(O)CN(c2ccccc2OCCOc1ccccc1N(CC(=O)O)CC(=O)O)CC(=O)O;
Properties
Chemical formula	C22H24N2O10
Molar mass	476.433
Density	1.494 g/cm3
Melting point	177 to 179 °C (351 to 354 °F; 450 to 452 K)
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

BAPTA (1,2-bis(o-amino phenoxy)ethane-N,N,N′,N′-tetraacetic acid) is an aminopolycarboxylic acid with a high affinity for calcium. It is a white solid. It is used in research to chelate Ca²⁺, as it behaves similarly to EGTA and EDTA.

Complexation

BAPTA, as its conjugate base, binds calcium ions as a decadentate ligand:

[CH₂OC₆H₄N(CH₂CO₂H)₂]₂ + Ca²⁺ → Ca[CH₂OC₆H₄N(CH₂CO₂)₂]2−2 + 4 H⁺

According to X-ray crystallography. the four carboxylates, two amines, and two ether oxygens bind to Ca²⁺.^[1]

There is a range of reported values for the dissociation constant of BAPTA, though 0.2 μM appears consistently.^[2] The rate constant for calcium binding is 500 μM⁻¹ s⁻¹.^[2] 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.^[3]

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.^[4]

References

^ Gerig, John T.; Singh, Phirtu; Levy, Louis A.; London, Robert E. (1987). "Calcium complexation with a highly calcium selective chelator: Crystal structure of ca(CaFBAPTA) ·5H2O". Journal of Inorganic Biochemistry. 31 (2): 113–121. doi:10.1016/0162-0134(87)80056-9.
^ ^a ^b Ricci AJ, Wu YC, Fettiplace R (15 October 1998). "The endogenous calcium buffer and the time course of transducer adaptation in auditory hair cells". The Journal of Neuroscience. 18 (20): 8261–77. doi:10.1523/JNEUROSCI.18-20-08261.1998. PMC 6792854. PMID 9763471.
^ Csomós, Attila; Kontra, Bence; Jancsó, Attila; Galbács, Gábor; Deme, Ruth; Kele, Zoltán; Rózsa, Balázs; Kovács, Ervin; Mucsi, Zoltán (Sep 2021). "A Comprehensive Study of the Ca2+ Ion Binding of Fluorescently Labelled BAPTA Analogues". European Journal of Organic Chemistry. 2021 (37): 5248–5261. doi:10.1002/ejoc.202100948.
^ "Fluorescent Ca2+ Indicators Excited with Visible Light—Section 19.3". The Molecular Probes Handbook. Retrieved 2024-01-22.

[1] Gerig, John T.; Singh, Phirtu; Levy, Louis A.; London, Robert E. (1987). "Calcium complexation with a highly calcium selective chelator: Crystal structure of ca(CaFBAPTA) ·5H2O". Journal of Inorganic Biochemistry. 31 (2): 113–121. doi:10.1016/0162-0134(87)80056-9.

[pmid9763471-2] Ricci AJ, Wu YC, Fettiplace R (15 October 1998). "The endogenous calcium buffer and the time course of transducer adaptation in auditory hair cells". The Journal of Neuroscience. 18 (20): 8261–77. doi:10.1523/JNEUROSCI.18-20-08261.1998. PMC 6792854. PMID 9763471.

[3] Csomós, Attila; Kontra, Bence; Jancsó, Attila; Galbács, Gábor; Deme, Ruth; Kele, Zoltán; Rózsa, Balázs; Kovács, Ervin; Mucsi, Zoltán (Sep 2021). "A Comprehensive Study of the Ca2+ Ion Binding of Fluorescently Labelled BAPTA Analogues". European Journal of Organic Chemistry. 2021 (37): 5248–5261. doi:10.1002/ejoc.202100948.

[4] "Fluorescent Ca2+ Indicators Excited with Visible Light—Section 19.3". The Molecular Probes Handbook. Retrieved 2024-01-22.

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BAPTA

Complexation

See also

References

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