Chemistry:TBE buffer
TBE or Tris/Borate/EDTA, is a buffer solution containing a mixture of Tris base, boric acid and EDTA.
In molecular biology, TBE and TAE buffers are often used in procedures involving nucleic acids, the most common being electrophoresis. Tris-acid solutions are effective buffers for slightly basic conditions, which keep DNA deprotonated and soluble in water. EDTA is a chelator of divalent cations, particularly of magnesium (Mg2+). As these ions are necessary co-factors for many enzymes, including contaminant nucleases, the role of the EDTA is to protect the nucleic acids against enzymatic degradation. But since Mg2+ is also a co-factor for many useful DNA-modifying enzymes such as restriction enzymes and DNA polymerases, its concentration in TBE or TAE buffers is generally kept low (typically at around 1 mM).
According to studies by Brody and Kern, sodium boric acid[lower-alpha 1] is a superior and cheaper conductive media for most DNA gel electrophoresis applications.[1][2]
Recipe (1 liter of 5X stock solution)
- 54 g of Tris base (CAS# 77-86-1, free base)
- 27.5 g of boric acid (CAS# 10043-35-3)
- 20 ml of 0.5 M EDTA (CAS# 60-00-4) (pH 8.0)
Adjust pH to 8.3 by HCl.[3]
TBE can be diluted to 1X prior to use in electrophoresis, 0.5x is acceptable as well. Higher concentrations will result in poor results due to excessive heat generation.
See also
- LB buffer, lithium borate buffer, a similar buffer containing lithium ions in place of Tris
- TAE buffer, a similar buffer containing acetic acid in place of boric acid
Notes
- ↑ 5 mM disodium borate decahydrate or 10 mM sodium hydroxide, pH adjusted to 8.5 with boric acid.
References
- ↑ Brody, J.R.; Kern, S.E. (2004). "History and principles of conductive media for standard DNA electrophoresis". Anal Biochem 333 (1): 1–13. doi:10.1016/j.ab.2004.05.054. PMID 15351274. http://www.cc.ahs.chula.ac.th/Molmed/DNA%20electro%27s%20conductive%20media.pdf.
- ↑ Brody, Jonathan R.; Kern, Scott E. (February 2004). "Sodium boric acid: a Tris-free, cooler conductive medium for DNA electrophoresis". BioTechniques 36 (2): 214–216. doi:10.2144/04362BM02.
- ↑ "5X TBE(1.1M Tris; 900mM Borate; 25mM EDTA; pH 8.3)". https://www.eeb.ucla.edu/Faculty/Barber/Web%20Protocols/Protocol7.pdf.
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