DO THE HEMEPROTEINS BEHAVE AS A DISSIPATIVE STRUCTURE

Continuing the search for a broader interpretation of hemeprotein beha vior, we give preliminary results showing that there are electric and dynamic couplings between the heme group and amino acid residues withi n the protein matrix. EPR and X-ray absorption spectroscopy studies on azidometmyoglobin show that both magnetic and geometric properties of Fe-N-3 evolve in the same nonlinear way as pH is increased and are ti ghtly correlated to the strains on the helical segments of the protein . Flash photolysis of carbon monoxide hemoglobin, in the presence of e thanol or formamide, allows the study of cosolvent effects on geminate and nongeminate recombinations of the CO ligand trapped within the pr otein matrix. Data clearly show that cosolvents alter the statistic fl uctuations of the protein, as well as the ligand partition between dif ferent protein matrix domains. From these studies, it is concluded tha t alterations occurring at particular sites give way to global protein perturbations. Then, each perturbated protein domain-binding site inc luded-evolves with its own sensitivity to a new metastable state of th e protein. The amplification of the initial perturbation which-instead of regressing-progressively propagates through the whole macromolecul e is typical of a dissipative structure in the Prigogine sense. Biolog ical properties of hemeproteins largely involve the surrounding solven t, via permanent or temporary exchanges of water molecules, protons, a nd small ligands. These fluxes along with their entropic corollary are not quite compatible with a conservative system. These works present the current trends developed in our laboratory in association with the European network ''The Dynamics of Protein Structure.'' In this frame work, our laboratory collaborates with Dr. W. Doster and T. Kleinert ( Munich, Germany) for the CO recombination studies in hemoglobin and wi th Dr. T. Hutterman (Homburg, Germany) and Drs. A. Bianconi and S. Del la Longa (Rome and L'Aquila, Italy) for the magnetic and geometric pro perties of the myoglobin iron site. (C) 1996 John Wiley & Sons, Inc.