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

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