Is re-association in folded proteins a case of nonextensivity?

Pioneering experiments by Frauenfelder and collaborators have shown that the ligands of iron (CO, O-2) in heme proteins such as myoglobin and hemoglobin, when photo-dissociated at temperatures up to about T* (for example, T* = 160 K for MbCO in glycerol-water) exhibit an anomalous (power-law, instead of exponential) rebinding behavior as a function of time. We show here that this behavior is consistent with nonextensive statistics that have been successfully applied to other physical phenomena. (C) 1999 Published by Elsevier Science B.V. All rights reserved.