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).
More recently discovered substitutes for TBE and TAE buffers for electrophoresis are available.[1]
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.[2]
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
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.
- ↑ https://web.archive.org/web/20171107223153/https://www.eeb.ucla.edu/Faculty/Barber/Web%20Protocols/Protocol7.pdf [bare URL PDF]
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