If cells lyse prematurely during the process of DNA isolation, it leads to degradation of the DNA and has an adverse effect on the yield. The glucose content in GTE buffer helps to maintain osmolarity of the isolation medium. As a result, the solute concentration outside the plasmid cells closely mimics that within the cells and prevents rupture. Unlike other salts with similar properties, glucose is not an electrolyte and therefore does not cause a change in the solution's buffering capacity.
Buffers are solutions resisting small changes in pH of the reaction mixture. In biotechnology experiments involving isolation of DNA from plasmids, it is important to maintain the pH of the solution at 8.0. This pH is ideal to prevent the plasmid DNA from degradation by acid hydrolysis. It also inhibits other undesirable reactions within cellular components that may interfere with the stability of the DNA. Tris (hydroxymethyl) amino methane helps maintain the desired pH level.
Certain nuclease enzymes present within the cell have the potential to degrade DNA. These enzymes require the presence of divalent cations such as calcium, zinc and magnesium as co-factors to bring about the degradation reactions. The EDTA present in the GTE buffer binds these divalent cations. This prevents action by the nuclease enzymes and helps obtain intact DNA at the end of the isolation process.
GTE is available as a biotechnology grade sterile solution. It is a colorless liquid with a pH of 8.0 and should be stored cold. Ensure you warm the buffer to room temperature before you open the container. Follow the aseptic technique when handling this buffer to prevent the growth of bacteria in the isolation medium. Study the manufacturer's usage and safety instructions before you use this solution.