ACTION OF RADIATION ON PROTEINS AND NUCLEIC 

 ACIDS IN SOLUTION AND AT INTERPHASES 



A. G. PASSYNSKY 



A. N. Bach Institute of Biochemistry, U.S.S.B. Academy of Sciences, 



Moscoiv, U.S.S.R. 



SUMMARY 



Measurement of the oxidation of the -SH groups of proteins, the linkages of 

 33S-methionine, the radiation destruction of DNA and many other methods 

 allow us to establish the presence of molecular changes in thousands of irradiated 

 molecules of proteins even for a dose of 400 to 500 r and in nucleoproteins for 20 to 

 50 r. However, the application of the statistical theory of the action of radiation 

 shows that the primarily irradiated volumes in the cell only have the dimensions 

 of a few molecules. When establishing the mechanism of biological "amplifi- 

 cation" of the action of radiation it is necessary to take into accovmt the par- 

 ticular significance of damage to the molecules of the biological macromolecules 

 which enter into the composition of the intracellular surfaces of the section 

 (cytoplasmic and nuclear membranes) and also the properties of the living cell 

 as an open system for which the alteration of the transfer constant is of great 

 significance. It has been shown that the appearance of chemical "cross-links" 

 in monolayers of DNA substantially destroys the structure and increases the area 

 of the monolayer, and radiation damage to the thin siu-face layers of RNA which 

 separate the enzyme from the substrate (peroxidase-ascorbic acid, H2O2) leads 

 to considerable acceleration of their interaction. The variation caused by the 

 damage of only several molecules in the surfaces of the section may be a source 

 of all the subsequent biochemical disruptions and radiation damage to the living 

 cells. 



Living cells and organisms are constantly interchanging matter and 

 energy with the surronnding medium, i.e. they form so-called "open 

 systems". Therefore the theory of the action of radiation on living 

 organisms must take into consideration the general properties of 

 reactions in open systems. According to the theory of open systems 

 (Burton, 1939; Denbigh et al., 1948; Passynsky, 1957a) stationary 

 concentrations of the components are determined not only by the rate- 

 constants of chemical reactions, as in closed systems, but also, to the 

 same extent, by the constants of the transfer of matter in the process 

 of free diffusion or of penetration through membranes. Consideration 

 of the constants of transfer, along with the coefficients of reaction rates 

 is an essential feature of the theory of open systems which reveals the 



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