:BAPTA
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 458976435
| ImageFile = BAPTA.svg
| ImageSize = 250px
| ImageAlt = Skeletal formula of BAPTA
| ImageClass = skin-invert
| ImageFile1 = BAPTA 3D ball.png
| ImageSize1 = 240
| ImageAlt1 = Ball-and-stick model of the BAPTA molecule
| PIN = 2,2′,2′′,2′′′-[Ethane-1,2-diylbis(oxy-2,1-phenylenenitrilo)]tetraacetic acid
| OtherNames =
|Section1={{Chembox Identifiers
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo =85233-19-8
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = K22DDW77C0
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 60888
| PubChem = 104751
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 94562
| SMILES = O=C(O)CN(c2ccccc2OCCOc1ccccc1N(CC(=O)O)CC(=O)O)CC(=O)O
| 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)
| InChIKey = FTEDXVNDVHYDQW-UHFFFAOYAD
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 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)
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = FTEDXVNDVHYDQW-UHFFFAOYSA-N }}
|Section2={{Chembox Properties
| Formula =C22H24N2O10
| MolarMass =476.433
| Appearance =
| Density =1.494 g/cm3
| MeltingPtC = 177 to 179
| MeltingPt_notes =
| BoilingPt =
| Solubility =
}}
|Section3={{Chembox Hazards
| MainHazards =
| FlashPt =
| AutoignitionPt =
}}
}}
BAPTA (1,2-bis(o-aminophenoxy)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:
:{{chem2|[CH2OC6H4N(CH2CO2H)2]2 + Ca(2+) -> 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+.{{cite journal |doi=10.1016/0162-0134(87)80056-9 |title=Calcium complexation with a highly calcium selective chelator: Crystal structure of ca(CaFBAPTA) ·5H2O |date=1987 |last1=Gerig |first1=John T. |last2=Singh |first2=Phirtu |last3=Levy |first3=Louis A. |last4=London |first4=Robert E. |journal=Journal of Inorganic Biochemistry |volume=31 |issue=2 |pages=113–121 }}
There is a range of reported values for the dissociation constant of BAPTA, though 0.2 μM appears consistently.{{cite journal |pmid=9763471 |pmc=6792854 |date=15 October 1998 |vauthors=Ricci AJ, Wu YC, Fettiplace R |title=The endogenous calcium buffer and the time course of transducer adaptation in auditory hair cells. |volume=18 |issue=20 |pages=8261–77 |journal=The Journal of Neuroscience |doi=10.1523/JNEUROSCI.18-20-08261.1998 }} 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.{{Cite journal |last1=Csomós |first1=Attila |last2=Kontra |first2=Bence |last3=Jancsó |first3=Attila |last4=Galbács |first4=Gábor |last5=Deme |first5=Ruth |last6=Kele |first6=Zoltán |last7=Rózsa |first7=Balázs |last8=Kovács |first8=Ervin |last9=Mucsi |first9=Zoltán |date=Sep 2021 |title=A Comprehensive Study of the Ca2+ Ion Binding of Fluorescently Labelled BAPTA Analogues |url=https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/ejoc.202100948 |journal=European Journal of Organic Chemistry |language=en |volume=2021 |issue=37 |pages=5248–5261 |doi=10.1002/ejoc.202100948}}
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.{{Cite web |url=https://www.thermofisher.com/de/de/home/references/molecular-probes-the-handbook/indicators-for-ca2-mg2-zn2-and-other-metal-ions/fluorescent-ca2-indicators-excited-with-visible-light.html |title=Fluorescent Ca2+ Indicators Excited with Visible Light—Section 19.3 |access-date=2024-01-22 |website=The Molecular Probes Handbook}}
See also
References
{{Reflist}}
{{Chelating agents}}
{{DEFAULTSORT:Bapta}}