Hyperchromic shift

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Hyperchromic shift describes the increase in ultraviolet light absorbance in DNA upon denaturation. Both native and denatured DNA are capable of absorbing UV light at a wavelength of 260nm due to the aromaticity of nitrogenous bases. However, the stacking of nitrogenous bases in native DNA interferes with UV absorption, resulting in a lower absorbance. Denaturation disrupts such stacking, allowing for more absorbance by the bases.