Article · Wikipedia archive · Last revised Jun 22, 2026

3-(4-Carboxybenzoyl)quinoline-2-carboxaldehyde

3-(4-Carboxybenzoyl)quinoline-2-carboxaldehyde (CBQCA) is a fluorogenic amine labeling dye that is not fluorescent itself, but covalently reacts with primary amines to form fluorescent products. It was first reported in 1991.

Last revised
Jun 22, 2026
Read time
≈ 1 min
Length
286 w
Citations
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Source
Wikipedia ↗
CBQCA
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Names
Preferred IUPAC name
4-(2-Formylquinoline-3-carbonyl)benzoic acid
Other names
CBQCA, ATTO-TAG CBQCA
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
  • InChI=1S/C18H11NO4/c20-10-16-14(9-13-3-1-2-4-15(13)19-16)17(21)11-5-7-12(8-6-11)18(22)23/h1-10H,(H,22,23)
    Key: MWNLTKCQHFZFHN-UHFFFAOYSA-N
  • C1=CC=C2C(=C1)C=C(C(=N2)C=O)C(=O)C3=CC=C(C=C3)C(=O)O
Properties
C18H11NO4
Molar mass 305.289 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

3-(4-Carboxybenzoyl)quinoline-2-carboxaldehyde (CBQCA) is a fluorogenic amine labeling dye that is not fluorescent itself, but covalently reacts with primary amines to form fluorescent products.1 It was first reported in 1991.2

CBQCA is largely used in the context of quantifying peptides or proteins. Either cyanide or thiols are required as a co-substrate in the fluorogenic reaction, although thiols also react with and mask the CBQCA aldehyde thereby preventing the fluorogenic reaction against the targeted primary amines.1 Once bound to protein the excitation wavelength is 465 nm (blue) and the emission wavelength is ~550 nm (green).3

Reaction

CBQCA, which is non-fluorescent, reacts with primary amines in the presence of cyanide to form fluorescent products:

See also

See also

References

References

  1. You, Wendy W.; Haugland, Rosaria P.; Ryan, Diane K.; Haugland, Richard P. (1997). "3-(4-Carboxybenzoyl)quinoline-2-carboxaldehyde, a Reagent with Broad Dynamic Range for the Assay of Proteins and Lipoproteins in Solution". Analytical Biochemistry. 244 (2). Elsevier BV: 277–282. doi:10.1006/abio.1996.9920. ISSN 0003-2697. PMID 9025944.
  2. Liu, Jinping.; Hsieh, You Zoung.; Wiesler, Donald.; Novotny, Milos. (1991-03-01). "Design of 3-(4-carboxybenzoyl)-2-quinolinecarboxaldehyde as a reagent for ultrasensitive determination of primary amines by capillary electrophoresis using laser fluorescence detection". Analytical Chemistry. 63 (5). American Chemical Society (ACS): 408–412. doi:10.1021/ac00005a004. ISSN 0003-2700. PMID 2064006.
  3. Fisher Scientific, Thermo. "CBQCA Protein Quantitation Kit - Product Information" (PDF). Retrieved 7 April 2023.