When doing a DNA extraction, what advantages does a TE buffer provide to DNA that water cannot?
To understand the advantages of using a Tris-EDTA (TE) buffer over water for DNA extraction, it is important to know the composition and function of both substances.
1. TE Buffer:
TE buffer is a commonly used solution in molecular biology and biochemistry. It consists of two main components:
- Tris Base (Tris(hydroxymethyl)aminomethane): It acts as a buffering agent to maintain a stable pH of the solution.
- EDTA (Ethylenediaminetetraacetic acid): It acts as a chelating agent, which binds and sequesters divalent metal ions (such as magnesium and calcium) that can negatively affect enzymatic reactions.
Advantages of using TE buffer in DNA extraction:
a. pH Stability: TE buffer maintains a stable pH around 8.0, which is optimal for many DNA-related processes. This stability prevents any pH fluctuations that may occur when using plain water, which could potentially denature the DNA.
b. Avoiding Enzyme Inhibition: EDTA in the TE buffer chelates divalent metal ions that are often present in water, such as magnesium. These metal ions can inhibit the activity of enzymes (e.g., DNA polymerases) used in subsequent DNA analysis. By sequestering these ions, TE buffer prevents enzyme inhibition, ensuring optimal enzymatic reactions during DNA extraction.
c. Reduced DNA Degradation: DNA is susceptible to degradation by nucleases (enzymes that break down DNA). Tris in the TE buffer provides a buffering capacity that helps maintain a stable pH, which can inhibit the activity of nucleases present in the sample. Water lacks this buffering capacity, making DNA more susceptible to degradation.
2. Water:
While water is essential for many laboratory procedures, it lacks the specific properties of TE buffer that benefit DNA extraction.
To summarize, the key advantages of using TE buffer over water in DNA extraction are its ability to maintain the stability of pH, prevent enzyme inhibition, and reduce DNA degradation by nucleases. These advantages ensure better preservation and yield of DNA during the extraction process.