PHYSICO-CHEMICAL INVESTIGATION OF THE MECHANISM OF ENZYME INACTIVATION. PART III. THERMODYNAMIC ANALYSIS OF STRUCTURAL AND CHEMICAL CHANGES IN PROTEIN DURING RADIATION INACTIVATION
ARMY BIOLOGICAL LABS FREDERICK MD
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A method for studying the structural and chemical changes during the individual stages of the radiation inactivation of enzymes is proposed, which consists of applying the Eyring-Stearn method of thermodynamic analysis of protein denaturing to the thermal radiation after-effect reaction. It was shown by this method that in the process of formation of latent damage in the myosin and pepsin molecules 10-15 hydrogen bonds are ruptured, but the covalent bonds are not ruptured in the second stage of inactivation -- upon realization of the latent damage -- the rupture of one covalent bond apparently the disulfide bond and 3-4 hydrogen bonds takes place. The hypothesis is expressed that the rupture of the hydrogen bonds in the first stage of inactivation takes place due to the Platzman-Franck polarization effect, but only after preliminary migration and localization of the charge at weak sites of the structure, particularly at the S-S bridges. Fusion of sections of the protein molecule in this region during the first stage of inactivation guarantees the possibility of carrying out the second stage.
- Radiation and Nuclear Chemistry