Question

A protein polypeptide chain exists in α-helical conformation in a solvent and it has a value of -30,000 deg cm2 dmol-1 for the mean residue ellipiticity at 222 nm ([θ]222) in the temperature range 20-50°C. On raising the temperature above 50°C,[θ]222 increases and reaches a value of -2,000 deg cm 2 dmol-1 at 70°C and the value of [θ]222 remains unchanged above 70°C. The observed value of [θ]222 is -14,000 deg cm 2dmol-1 at 60°C. If one assumes that the heat-induced denaturation is a two-state process, the fraction of α-helix at 60°C is

Answer 1

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