OXIDATION OF SUBSTANCES OF BIOLOGICAL IMPORTANCE 227 



mechanism of the changes produced in the porphyrin nucleus and in 

 the protein portion is as yet unknown. Perhaps some of these effects 

 are the result of direct collision. 



Fig. 8. Effect of x-ray irradiation on the absorption spectrum of ferricytochrome c, 



dissolved in 0.005 M phosphate buffer, pH 7.72. Abscissa: Wave length in angstrom 



units; ordinate: optical density E. 



A large number of other systems of biological importance may be 

 oxidized by the products of irradiated water or perhaps directly by the 

 withdrawal of electrons by the ionizing radiation. A systematic study 

 of these oxidations is being made in my laboratory. 



