Before revision:  This motion is qualitatively similar to that in terminal residues, with the same exponent in the power-law relaxation decay. The breathing dynamics is transmitted to the photoprobe by direct contacts between aromatic \pi orbitals of stacked bases .
After revision:  This motion is qualitatively similar to that in terminal base pairs. A physical mechanism is proposed to explain the coupling between the relaxation of base-pair breathing and the experimental response signal. It is concluded that the algebraic relaxation observed experimentally is very likely a manifestation of weakly chaotic dynamics of hydrogen-bond breathing in the base pairs stacked to the photoprobe by direct contacts between aromatic \pi orbitals of stacked bases .