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^[a] is a superior and cheaper conductive media for most DNA gel electrophoresis applications.^[1][2]

• 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.

• 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