Biological buffers and their interactions with metal ions
Knowing the complexing properties of biological buffers is extremely important when studying systems with metal ions. The reason is simple: protons are released when a buffer forms complexes with metal ions. As a result the pH value of a solution decreases considerably in these situations.
Additionally, metal complexation can be a problem in enzyme assays, since many enzymes need metal ions for maintaining their activity.
Some biological buffers have very low metal-binding constants, making them excellent choices to investigate metal-dependent enzymes. Good examples of buffers suitable for the use in solutions containing metal ions are HEPES, MOPS and PIPES. Other options, however, have higher metal-binding constants, making them less suitable options.
Although there is no consensus in the academia about the complex formation characteristics of each biological buffer, we present here some useful references in this field.
Check below the list of biological buffers produced by Hopax Fine Chemicals and how they interact with metal ions:
|Buffer||Useful pH range||Strong interaction with||Weak interaction with||Does not
|MES||5.5 - 6.7||Fe||Cu, Mg, Mn, Ni||-||Specs / Price|
|BIS-TRIS||5.8 - 7.2||Cu, Pb||Mg, Ca, Mn, Co, Ni, Zn, Cd||-||Specs / Price|
|ACES||6.1 - 7.5||Cu, Mg||Ca, Mn, Co, Ni, Zn||-||Specs / Price|
|PIPES||6.1 - 7.5||-||Co, Ni||-||Specs / Price|
|MOPSO||6.2 - 7.6||Fe||Ni||-||Specs / Price|
|BES||6.4 - 7.8||Cu||Co||Mg, Ca,Mn||Specs / Price|
|MOPS||6.5 - 7.9||Fe||Mg, Mn, Co, Ni||-||Specs / Price|
|HEPES||6.8 - 8.2||Negligible metal ion binding||-||-||Specs / Price|
|TES||6.8 - 8.2||Cu, Cr, Fe||Co, Ni, Zn||-||Specs / Price|
|TRIS||7.2 - 9.0||Cr, Fe, Co, Ni, Cu||Mg, Ca, Zn, Cd, Pb||-||Specs / Price|
|HEPPS||7.3 - 8.7||n/a||n/a||n/a||Specs / Price|
|TRICINE||7.4 - 8.8||Mg, Ca, Co, Cu, Ni, Zn||Mn||-||Specs / Price|
|GLYCYLGLYCINE||7.5 - 8.9||Cu||Mn||-||Specs / Price|
|BICINE||7.6 - 9.0||Cu, Fe, Co, Mg, Ca, Ni, Zn, Cd||Mn||-||Specs / Price|
|CHES||8.6 - 10.0||-||Cu, Pb, Cd, Zn||-||Specs / Price|
|CAPSO||8.9 - 10.3||No reported ion interaction||-||-||Specs / Price|
|CAPS||9.7 - 11.1||Negligible metal ion binding||-||-||Specs / Price|
Further reading:Useful pH range of Biological Buffers
Hopax Biological Buffers
Hopax Fine Chemicals is among the largest manufacturers of biological buffers in the world. Our products are shipped daily to top research centers and biotech companies in Europe, America and Asia.
What we offer:
- 30 buffers straight from our manufacturing sites
- Small and bulk packages (from grams to tons)
- International quality standards
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- Assistance with shipping
- After-sales service with English speaking staff
1 Wyrzykowski, D., Pilarski, B., Jacewicz, D., Chmurzynski, L. (2013) Investigation of metal–buffer interactions using isothermal titration calorimetry, J Therm Anal Calorim, 111:1829–1836. Available at https://www.researchgate.net/publication/257615954_Investigation_of_metal-buffer_interactions_using_isothermal_titration_calorimetry
2 Scheller, Kurt H., Abel, Thomas H. J., Polanyi, Peter E., Wenk, Peter K., Fischer, Beda E., and Sigel, Helmut (1980) Metal Ion/Buffer Interactions. Stability of Binary and Ternary Complexes Containing 2- [Bis (2-hydroxyethyl) amino]-2(hydroxyme thy1)- 1,3-propanediol (Bistris) and Adenosine 5'-Triphosphate (ATP), Eur. J. Biochem. 107, 455-466. Available at https://febs.onlinelibrary.wiley.com/doi/full/10.1111/j.1432-1033.1980.tb06051.x
3 Zawisza, I., Rózga, M., Poznański, J., Bal, W. (2013) Cu(II) complex formation by ACES buffer, Journal of Inorganic Biochemistry 129, 58–61. Available at https://www.sciencedirect.com/science/article/pii/S0162013413002171
4 Ferreira, C.M., Pinto, I.S., Soares, E.V., Soares, H.M. (2015) (Un)suitability of the use of pH buffers in biological, biochemical and environmental studies and their interaction with metal ions – a review, Royal Society of Chemistry 30989- 31003. Available at https://repositorium.sdum.uminho.pt/bitstream/1822/38712/1/document_19948_1.pdf
5 Yu, Q., Kandegedara, A., Xu, Y., Rorabacher, D.B. (1997) Avoiding interferences from Good's buffers: A contiguous series of noncomplexing tertiary amine buffers covering the entire range of pH 3-11, Anal Biochem. 1997 Nov 1; 253(1):50-6. Available https://www.ncbi.nlm.nih.gov/pubmed/9356141
6 Vasconcelos, M. T. S. D., Azenha, M. A. G. O., and Lage, O. M. (1996) Electrochemical Evidence of Surfactant Activity of the Hepes pH Buffer Which May Have Implications on Trace Metal Availability to Cultures in Vitro, Analytical Biochemistry 241, 248–253. Available at https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.535.9527&rep=rep1&type=pdf
7 Boraei, A. A. A. & Ahmed, I. T. (2007) Divalent transition metal ion mixed-ligand complexes of Tricine or glycylglycine and 8-hydroxyquinoline: synthesis, characterization, and formation constants, Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry, 32:6, 981-1000. Available at https://www.tandfonline.com/doi/abs/10.1081/SIM-120005616
8 Krishnamoorthy, C. R., & Nakon, R. (2009) Free Metal Ion Depletion by Good's Buffers. IV. Bicine 1:1 and 2:1 Complexes with Mg(II), Ca(II), Mn(II), Co(II), Ni(II), Cu(II) and Zn(II), Journal of Coordination Chemistry, 23:1-4, 233-243. Available at https://www.tandfonline.com/doi/abs/10.1080/00958979109408254
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