Practice question

Spectral intensity terminology distinguishes hyperchromic from bathochromic effects. Hyperchromic shift denotes increase in absorption intensity at given wavelength, reflected as elevated molar extinction coefficient ε and absorbance while concentration and path length unchanged. Upon thermal denaturation of double-stranded DNA, disruption of base stacking reduces electronic coupling, increasing ε by nearly forty percent at 260 nm. Similarly protein unfolding can increase A280. Parameter increasing during hyperchromic transition is therefore ε, not λmax, c or l, providing quantitative measure of structural changes, duplex stability and melting temperature in nucleic acid biophysical studies.