DNA denaturation and renaturation processes are used for genetic research and studies. In the process of denaturation, an unwinding of DNA double-strand takes place, leading to two separate single strands on applying heat. Separate single strands rewind on cooling and the process is known as renaturation.
Denaturation and renaturation kinetics are used to determine the size and complexity of the genome. It also wants to understand the relativity of two genomes and repetitive sequences present during a genome.
Denaturation and Renaturation of DNA - Difference
The table below shows the foremost difference between Denaturation and Renaturation of DNA
What is Denaturation?
DNA has a double-stranded helical structure. The stability of the DNA structure gets affected by many factors.
In the denaturation process, the hydrogen bonds between two strands are broken giving rise to two single strands. The covalent bonds of DNA remain unaffected.
Denaturation Can be Brought by Various Methods:
Thermal Denaturation: Denaturation can be done by heating (>80-90℃). The temperature at which DNA is half denatured is named critical temperature or melting temperature, Tm. Tm depends on the length and composition of the DNA bases and other factors like pH and denaturing agents.
Extreme pH: At high pH (>11.3), hydrogen bonds between base pairs of two strands of DNA dissociate due to presence of abundant OH– ion. It results in denaturation of DNA.
Other Denaturing Agents: Low salt concentrations destabilise hydrogen bonds. Formaldehyde and urea have a tendency to form hydrogen bonds with nitrogen bases and aldehydes also prevent hydrogen bonding between base pairs by modifying electronegative centres of nitrogenous bases.
Effect of denaturation of DNA:
Increased absorption of UV light at 260nm wavelengths. The rate of absorption is directly proportional to the rate of denaturation.
Viscosity decreases, which reflects the physical change occurred in the DNA structure.
What is Renaturation?
Renaturation is also known as annealing. When the temperature and pH return to optimum biological level, the unwound strand of DNA rewind and give back the dsDNA.
If the DNA isn't completely denatured, the renaturation process is fast and a one-step process, but if the DNAs are completely denatured then the renaturation process occurs during a two-step process. First complementary strands come together by random collision and then rewinding happens that forms a double helix.
Renaturation occurs when the denatured DNAs are cooled in suitable conditions. Renaturation also depends on temperature, pH, length and constituents of the DNA structure. The renaturation rate is directly proportional to the number of complementary sequences present. By the process of renaturation, absorption of UV (260nm) decreases and viscosity increases again.