Ponceau S

Ponceau S

Identifiers
CAS Number	6226-79-5
3D model (Jmol)	Interactive image
ChEBI	CHEBI:90319
ECHA InfoCard	100.025.745
InChI InChI=1S/C22H16N4O13S4/c27-22-20(43(37,38)39)10-12-9-16(41(31,32)33)6-7-17(12)21(22)26-25-18-8-3-14(11-19(18)42(34,35)36)24-23-13-1-4-15(5-2-13)40(28,29)30/h1-11,27H,(H,28,29,30)(H,31,32,33)(H,34,35,36)(H,37,38,39)/b24-23+,26-25+
SMILES OC1=C(N=NC3=CC=C(N=NC4=CC=C(S(=O)(O)=O)C=C4)C=C3S(=O)(O)=O)C2=C(C=C(S(=O)(O)=O)C=C2)C=C1S(=O)(O)=O
Properties
Chemical formula	C22H16N4O13S4
Molar mass	672.63 g·mol^−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Ponceau S, Acid Red 112, or C.I. 27195 (systematic name: 3-hydroxy-4-(2-sulfo-4-[4-sulfophenylazo]phenylazo)-2,7-naphthalenedisulfonic acid sodium salt^[1]) is a sodium salt of a diazo dye of a light red color, that may be used to prepare a stain for rapid reversible detection of protein bands on nitrocellulose or polyvinylidene fluoride (PVDF) membranes (Western blotting), as well as on cellulose acetate membranes.^[2] A Ponceau S stain is useful because it does not appear to have a deleterious effect on the sequencing of blotted polypeptides and is therefore one method of choice for locating polypeptides on Western blots for blot-sequencing.^[2] It is also easily reversed with water washes, facilitating subsequent immunological detection.^[2] The stain can be completely removed from the protein bands by continued washing.^[2] Common stain formulations include 0.1% (w/v) Ponceau S in 5% acetic acid or 2% (w/v) Ponceau S in 30% trichloroacetic acid and 30% sulfosalicylic acid.^[3]

A nitrocellulose membrane stained with Ponceau S dye for protein detection during western blotting. The blue bands on the left are protein markers for various molecular weights.

See also

• Coomassie Brilliant Blue
• Western blot normalization

References

1. "Ponceau S solution". Sigma-Aldrich. Retrieved 2016-11-24.
2. Al-Amoudi, M. S.; Salman, Mahmoud; Al-Majthoub, M. M.; Adam, Abdel Majid A.; Alshanbari, Naif A.; Refat, Moamen S. (9 October 2013). "Spectral studies to increase the efficiency and stability of laser dyes by charge-transfer reactions for using in solar cells: charge-transfer complexes of Ponceau S with p-chloranil, chloranilic and picric acids". Research on Chemical Intermediates. doi:10.1007/s11164-013-1417-4.
3. "Ponceau S solution". Sigma-Aldrich. Retrieved 2016-11-24. The following are two common stain formulations…