Biological Buffers


Synonym: 2-(N-Morpholino)ethanesulfonic acid, 4-Morpholineethanesulfonic acid

MES is a zwitterionic N-substituted aminosulfonic acid known as a Good’s buffer, active in the pH range 5.5-6.7 with a pKa of 6.10 at 25°C. MES is not absorbed through cell membranes, and it is essentially transparent to UV light1. MES is used as a running buffer for resolving very small proteins (ex: 13 kDa) on BIS-TRIS gels2.
Useful pH Range 5.5 - 6.7
Working concentration range 30mM-50mM6,7


        Comparison of products by grade or quality level
Name CAS Molecular Formula Mol Wt Reagent Grades Life Science Grades PharmaGrade  Solutions
M3671     76039
MES hydrate 1266615-59-1 C6H13NO4S • xH2O 195.24 M8250 M2933
M5287 69890
MES monohydrate 145224-94-8 C6H13NO4S • H2O 213.25   69889
MES sodium salt 71119-23-8 C6H12NNaO4S 217.22 M5057 M3885 M3058  PHG0008 RES0114M-A7   
MES potassium salt 39946-25-3 C6H12KNO4S 233.33 M0895      
MES hemisodium salt 117961-21-4 C6H13NO4S • 0.5Na 206.73 M0164 M8902      


Interaction Comments

MES weakly binds Cu, Mg, Mn, Ni and Cu (II).3 MES strongly binds Fe(III).5
MES stabilizes BSA4.
MES is also useful as a non-coordinating buffer in chemistry involving metal ions, as many common buffers (e.g. phosphate and acetate) readily form coordination complexes.3


Literature References

  1. Good, N.E., et al. 1966. Biochemistry. 5: 467-477. PMID: 5942950
  2. Graf, H., et al. 1994. Bioseparation. 4: 7-20. PMID: 7764588
  3. Kandegedara, A.; Rorabacher, D. B. 1999. Anal. Chem. 71: 3140–3144.
  4. Taha, Mohamed. et al. 2011. Macromolecules. 44.21: 8575-8589.
  5. Ferreira CM, Pinto IS, Soares, EV, Soares HM. 2015 Royal Society of Chemistry 30989- 31003
  6. Lorian V–Antibiotics in Laboratory Medicine—Lippincort Williams &Wilkins 2005 pp. 605
  7. Perron NR, Dissertation Effects of polyphenol compounds on iron and copper-mediated DNA damage: mechanisms and predictive models, Proquest 2008 pp. 119