- #1
(emphasis mine)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.
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.
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.
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.
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.
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.