Is DNA Stable in Water?
No, DNA is not inherently stable in water for extended periods at room temperature. While it can exist in water, various factors contribute to its degradation.
- Hydrolysis: Water molecules can break the chemical bonds within the DNA backbone, leading to fragmentation. This process is accelerated by higher temperatures.
- Enzymatic Degradation: Enzymes, such as nucleases, readily break down DNA in aqueous solutions. These enzymes are present in many biological samples and can contaminate water, accelerating DNA degradation.
- Chemical Instability: The DNA structure itself is chemically unstable and susceptible to degradation over time in aqueous solutions.
Improving DNA Stability in Water
While DNA is inherently unstable in water, specific measures can enhance its stability:
- Low Temperatures: Storing DNA at low temperatures (e.g., 4°C or -20°C) significantly slows down degradation rates. Freezing at -80°C offers even better protection.
- Buffers: Adding buffers like Tris-EDTA (TE buffer) to the water helps maintain a stable pH and chelates metal ions that can catalyze degradation. TE buffer has been shown to be better than pure water for short-term storage.
- Glycerol: Adding glycerol to aqueous DNA solutions can provide protection, though studies show significant degradation even with glycerol after multiple freeze-thaw cycles.
- Avoiding Freeze-Thaw Cycles: Repeated freezing and thawing causes physical stress that damages the DNA and accelerates its degradation.
- Purification Methods: High-quality purification during DNA extraction minimizes the presence of contaminants that can contribute to degradation.
A study found similar degradation rates for DNA stored in water or 50% glycerol, with over 75% degradation observed after 16 freeze-thaw cycles. (Nature, 2021). Another source confirms that DNA is not stable in aqueous solutions at room temperature for long periods due to degradation by nucleobases and chemical instability. (Lindahl and Nyberg, 1972; Sasaki et al., 2007). Note that while some sources mention short-term stability at room temperature in certain conditions, long-term stability necessitates specific storage protocols. Further, storage in buffers like TE is preferable to pure water.
