indo-1
{{short description|Chemical compound used as an indicator in calcium imaging}}
{{Chembox
| Watchedfields = changed
| verifiedrevid = 443873843
| ImageFile = Indo-1.svg
| ImageSize = 250px
| IUPACName = 2-[4-(bis(carboxymethyl)amino)-3-[2-[2-(bis(carboxymethyl)amino)-
5-methylphenoxy]ethoxy]phenyl]-1H-indole-6-carboxylic acid
| SystematicName =
| OtherNames = Indo-1
|Section1={{Chembox Identifiers
| Abbreviations =
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 94791
| InChI = 1/C32H31N3O12/c1-18-2-6-24(34(14-28(36)37)15-29(38)39)26(10-18)46-8-9-47-27-13-20(5-7-25(27)35(16-30(40)41)17-31(42)43)22-11-19-3-4-21(32(44)45)12-23(19)33-22/h2-7,10-13,33H,8-9,14-17H2,1H3,(H,36,37)(H,38,39)(H,40,41)(H,42,43)(H,44,45)
| InChIKey = AMHAQOBUZCQMHN-UHFFFAOYAU
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/C32H31N3O12/c1-18-2-6-24(34(14-28(36)37)15-29(38)39)26(10-18)46-8-9-47-27-13-20(5-7-25(27)35(16-30(40)41)17-31(42)43)22-11-19-3-4-21(32(44)45)12-23(19)33-22/h2-7,10-13,33H,8-9,14-17H2,1H3,(H,36,37)(H,38,39)(H,40,41)(H,42,43)(H,44,45)
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = AMHAQOBUZCQMHN-UHFFFAOYSA-N
| CASNo_Ref = {{cascite|correct|??}}
| CASNo = 96314-96-4
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = N18RMK75W1
| EINECS =
| PubChem = 105060
| SMILES = O=C(O)CN(c4ccc(cc4OCCOc3c(N(CC(=O)O)CC(=O)O)ccc(c2cc1ccc(cc1[nH]2)C(=O)O)c3)C)CC(=O)O
| RTECS =
| MeSHName =
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 52084
| KEGG_Ref = {{keggcite|correct|kegg}}
| KEGG =
}}
|Section2={{Chembox Properties
| MolarMass = 649.60 g/mol
| Appearance =
| Density =
| MeltingPt =
| MeltingPt_notes =
| BoilingPt =
| BoilingPt_notes =
| Solubility =
| SolubleOther =
| Solvent =
| LogP =
| VaporPressure =
| HenryConstant =
| AtmosphericOHRateConstant =
| pKa =
| pKb =
}}
|Section3={{Chembox Structure
| CrystalStruct =
| Coordination =
| MolShape =
}}
|Section4={{Chembox Thermochemistry
| DeltaHf =
| DeltaHc =
| Entropy =
| HeatCapacity =
}}
|Section5={{Chembox Pharmacology
| AdminRoutes =
| Bioavail =
| Metabolism =
| HalfLife =
| ProteinBound =
| Excretion =
| Legal_status =
| Legal_US =
| Legal_UK =
| Legal_AU =
| Legal_CA =
| Pregnancy_category =
| Pregnancy_AU =
| Pregnancy_US =
}}
|Section6={{Chembox Explosive
| ShockSens =
| FrictionSens =
| DetonationV =
| REFactor =
}}
|Section7={{Chembox Hazards
| ExternalSDS =
| MainHazards =
| NFPA-H =
| NFPA-F =
| NFPA-R =
| NFPA-S =
| FlashPt =
| AutoignitionPt =
| ExploLimits =
| LD50 =
| PEL =
}}
|Section8={{Chembox Related
| OtherAnions =
| OtherCations =
| OtherFunction =
| OtherFunction_label =
| OtherCompounds =
}}
}}
Indo-1 is a popular dye that is used as a ratiometric calcium indicator similar to Fura-2. In contrast to Fura-2, Indo-1 has a dual emissions peak and a single excitation. The main emission peak in calcium-free solution is 475 nm while in the presence of calcium the emission is shifted to 400 nm. It is widely used in flow cytometry and laser scanning microscopy, due to its single excitation property. However, its use for confocal microscopy is limited due to its photo-instability caused by photobleaching. Indo-1 is also able to keep possession of its ratiometric emission, dissimilar to Fura-2.{{Cite journal |last=Paredes |first=R. Madelaine |last2=Etzler |first2=Julie C. |last3=Watts |first3=Lora Talley |last4=Zheng |first4=Wei |last5=Lechleiter |first5=James D. |date=November 2008 |title=Chemical calcium indicators |url=https://linkinghub.elsevier.com/retrieve/pii/S104620230800159X |journal=Methods |language= |volume=46 |issue=3 |pages=143–151 |doi=10.1016/j.ymeth.2008.09.025|pmc=2666335 }}
The penta potassium salt is commercially available and preferred to the free acid because of its higher solubility in water. While Indo-1 is not cell permeable the penta acetoxymethyl ester Indo-1 AM enters the cell where it is cleaved by intracellular esterases to Indo-1.
The synthesis and properties of Indo-1 were presented in 1985 by the group of Roger Y Tsien.{{cite journal
|vauthors=Grynkiewicz G, Poenie M, Tsien RY | title = A new generation of Ca2+ indicators with greatly improved fluorescence properties
| journal = J. Biol. Chem.
| volume = 260
| issue = 6
| pages = 3440–50
| year = 1985
| pmid = 3838314
| doi =10.1016/S0021-9258(19)83641-4
| doi-access = free
}}
In intact heart muscle, Indo-1, in combination with bioluminescent protein aequorin, can be utilized as a tool to distinguish between the internal and exterior inotropic regulation processes.{{Cite journal |last=Endoh |first=Masao |date=2006 |title=Signal Transduction and Ca2+ Signaling in Intact Myocardium |url=http://www.jstage.jst.go.jp/article/jphs/100/5/100_5_525/_article |journal=Journal of Pharmacological Sciences |language=en |volume=100 |issue=5 |pages=525–537 |doi=10.1254/jphs.CPJ06009X |issn=1347-8613}}