Luckau Protocols:Low TE

Purpose

Low TE buffer is used to store DNA.

• EDTA chelates Mg²⁺ and other divalent metals ions (inhibits DNAse and RNAse tp suppress DNA and RNA degradation)
• Tris is a buffering agent to keep the solution at a defined pH

Protocol

1x Low TE = 10 mM Tris-HCl + 0.1 mM EDTA

for 1 liter of 1x Low TE

volume	reagent	final conc.
20 ml	0.5M Tris-HCl, pH 8.0	10 mM
0.2 ml	0.5M EDTA, pH 8.0	0.1 mM
979.8 ml	ddH2O

• Sterilize by autoclaving for 20 min at 15 psi (1.05 kg/cm2) on liquid cycle
• Store at 4°C or room temperature

FYI

• Note, downstream reactions (PCR) typically require Mg²⁺, potentially making the presence of EDTA in the reaction problematic. So, when using DNA or RNA that was suspended in TE, keep track of the amount of EDTA in the mix to make sure there is still enough Mg²⁺ for subsequent reactions to proceed successfully. Each EDTA molecule chelates one Mg²⁺ ion.
• Many protocols use TE (10mM Tris-Cl and 1mM EDTA), so note that Low TE is different from TE.
• Some people use TE buffers with different pH's for different applications
  • DNA is stored at pH 8 to reduce depurination, which is acid catalyzed
  • RNA is stored at a slightly lower pH (7.5) because degradation of RNA is base-catalyzed
  • Most downstream reactions will not be influenced by the slightly different pH storage conditions.

Sources

• OpenWetWare's Materials TE page
• Cold Spring Harb Protoc; 2006; doi:10.1101/pdb.rec8018
• 10x and 1x TE at cytographica