EFFECT OF RADIATION ON PROTEINS 319 



However, the serum proteins in the blood of an animal exposed to pene- 

 trating radiation may be denatured to some extent and, although no 

 experimental evidence has been given on this point, it is probable that 

 denaturation would result in a larger globulin-albumin ratio and this 

 in turn would result in a change in the amount of bound water. 



The fact that after radiation the water-binding capacity of proteins 

 is much diminished would lead to physiological changes throughout the 

 animal body and the effect of radiation may be profound in higher 

 animals as well as in microorganisms. Fortunately the rapidly effective 

 ultra-violet rays do not penetrate deeply enough to produce widespread 

 injury. 



REFERENCES 



1. Anson, M. L., and A. E. Mirsky. The preparation of completely coagulated 

 hemoglobin. Jour. Gen. Physiol. 13: 121-132. 1929. 



2. Anson, M. L., and A. E. Mirsky. The preparation of insoluble globin, soluble 

 globin and heme. Jour. Gen. Physiol. 13: 469-476. 1929. 



3. Becker, J. P., and P. Szendro. Spektralanaljiiische und chemische Unter- 

 suchungen liber den Abbau von Eiweiss durch ultraviolette Strahlen. Pfliiger's 

 Arch. Ges. Physiol. 228: 755-763. 1931. 



4. BoviE, W. T. The temperature coefficient of the coagulation caused by ultra- 

 violet light. Science 37 : 373-375. 1913. 



5. BoviE, W. T., and O. C. Woolpert. On the mechanism of the light action on 

 solutions of albumen. Science 60: 70. 1924. 



6. Chalupecky, H. Der Einfluss der ultravioletten Strahlung auf die Augenlinse. 

 Wien. Med. Wochensch. 63: 1986-1991. 1913. 



7. Chick, Harriette, and C. J. Martin. On the "heat coagulation" of proteins. 

 Jour. Physiol. 40: 404-430. 1910. 



* Since this review was written some work carried out by the author, which is 

 now in press, has thrown light on a number of the questions raised in this review. 

 Salt-free isoelectric egg albumin was given ultra-violet radiation and the amount of 

 material subsequently precipitated was determined quantitatively by the Tyndall 

 beam from the opalescent solutions. Coagulation as the result of radiation was 

 found to take place in three steps. If salt-free isoelectric egg albumin is radiated at 

 4°C. the initial change, the light-denaturation of the protein molecule, occurs without 

 the secondary changes which result in coagulation. This primary process was found 

 to be unimolecular with a temperature coefficient of 1. It must therefore be a phys- 

 ical change resulting in a new configuration of the molecule with different physical 

 and chemical properties. The second step in the coagulation process is a reaction 

 between the light-denatured molecule and water which has the high temperature 

 coefficient of 10. The second step may be similar to heat denaturation of the protein 

 molecule but occurs at a lower temperature. Heat denaturation does not proceed 

 at an appreciable rate below 50°C. whereas the heat change following light-denatura- 

 tion takes place at an appreciable rate at 10°C. and proceeds rapidly at 40°C. The 

 final step is the flocculation of the light- and heat-denatured molecules. The change 

 taking place in salt-free proteins as a result of radiation, therefore, which is called 

 light-denaturation, is not sufficient in itself to produce coagulation. It is followed by 

 flocculation if the radiated proteins are heated to a moderate temperature for a short 

 time. 



