DNA is Held Together by a Watery Environment

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In summary, scientists were wrong about DNA being solely held together by hydrogen bonds. It has been known for over half a century that hydrophobic forces and base stacking are also key factors in the stability of DNA's double helix structure, as demonstrated in a 1962 study by Herskovits. More recent experiments, such as one from 1998, have also shown that an artificial DNA base pair can function without hydrogen bonding.
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What were scientists wrong about? We have already known this for over half a century:

Herskovits. Nonaqueous solutions of DNA: Factors determining the stability of the helical configuration in solution. Arch. Biochem Biophys 97: 474 (1962)

Abstract:
The disorganization of the aqueous helical configuration of deoxyribonucleic acid (DNA) by a number of structurally related organic solvents has been investigated. In all the solvents investigated, denaturation is accompanied by 35–50% increase in absorbance (at 259 mμ) and a decrease in optical rotation (at 436 mμ) of 200–350 °. The following observations have been made: (a) The effectiveness of the denaturant increases with both chain length and increasing hydrocarbon content. Thus ethyl and propyl alcohols were found to be more effective than methanol. (b) The alkyl-substituted solvents N,N′-dimethylformamide, dimethyl sulfoxide, and tetramethylurea are the most effective denaturants among the various solvents employed. The midpoints of the denaturation transition due to these solvents in the presence of 1–5 × 10−2M salt, range from 19 to 27 mole % (57–62 vol.%), and the changes produced in optical rotation (at 436 mμ) upon denaturation are of the order of −300 to −350 °. (c) N,N′-dimethylformamide is a more effective DNA denaturant than formamide. (d) Increasing the hydroxyl content of the solvent, on the other hand, had no significant effect; the denaturation midpoints in methanol-water and ethylene glycol-water mixtures (in the presence of 0.5–5 × 10−2M salt) occur at 80 ± 1 mole % (90 ± 2 vol.%) of the nonaqueous component. These observations demonstrate the importance of hydrophobic forces and argue against the assignment of the stability of the aqueous configuration of DNA solely to hydrogen bonds.
(emphasis mine)
https://www.sciencedirect.com/science/article/pii/0003986162901108
The fact that the hydrophobic effect and base stacking are key to the stability of double stranded DNA has been demonstrated in numerous experiments, including a classic study from over two decades ago, where chemists synthesized an artificial DNA base pair that works without hydrogen bonding:

Matray and Kool. Selective and Stable DNA Base Pairing without Hydrogen Bonds. J Am Chem Soc 120:6191 (1998)
https://pubs.acs.org/doi/10.1021/ja9803310
 
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FAQ: DNA is Held Together by a Watery Environment

1. What is the role of water in holding DNA together?

Water is essential for the stability of DNA molecules. It acts as a solvent, surrounding and interacting with the charged phosphate backbone of the DNA, which helps to keep the strands together.

2. How does the watery environment affect the structure of DNA?

The hydrogen bonds that hold the two strands of DNA together are weakened by the presence of water molecules, making it easier for the strands to separate and allowing for processes such as DNA replication and transcription to occur.

3. Can DNA be held together without a watery environment?

No, DNA requires a watery environment to maintain its structure and function. In a dry environment, the DNA strands would separate, making it impossible for the molecule to carry out its biological functions.

4. Does the amount of water affect the stability of DNA?

Yes, the amount of water present can affect the stability of DNA. Too much water can cause the strands to separate too easily, while too little water can make the molecule too rigid and unable to function properly.

5. Can other molecules besides water also hold DNA together?

Yes, other molecules such as salts and proteins can also play a role in holding DNA together. These molecules can interact with the DNA strands and help to stabilize the molecule in a similar way to water.

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