General Properties of Nucleic Acids
- Double helical DNA and RNA can be denatured.
a. Disruption of hydrogen bond causes unwinding of double helical structure( also called Partial denaturation).
b. When the temperature or pH is returned to normal stand, the two strands spontaneously rewind to yield intact duplex ( also called renaturation).
Renaturation occurs in two steps.
- Two strands find each other by random collision and form a short segment of complementary double helix.
- Unpaired base pair changes to paired base pair and the two strands ‘zipper’ themselves to form double helix.
c. Viral or bacterial DNA molecule in solution denature when they are heated slowly. i.e. the higher its content of C≡ G base pair, the higher the melting point of DNA.
2. Nucleic acids from different species can form hybrids. Human DNA hybridizes much more extensively with mouse DNA than with yeast DNA.
3. Nucleotides and Nucleic acids undergoes non-enzymatic transformations.
a. Purine and pyrimidines undergo a no. of spontaneous alterations in their covalent structures.
b. Hydrolysis of N-glycosyl bond between the base and pentose occurs at higher rate for purine than fr pyrimidine.
c. Depurination of ribonucleotide and RNA is much slower.