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.
Recipe (1 liter of 5X stock solution)
- 54 g of Tris base (CAS# 77-86-1)
- 27.5 g of boric acid (CAS# 10043-35-3)
- 20 ml of 0.5 M EDTA (CAS# 60-00-4) (pH 8.0)
TBE can be diluted to 1X prior to use in electrophoresis, 0.5x is acceptable as well.
- 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