EFFECT OF RADIATION ON PROTEINS 



317 



The denaturation of proteins by radiation may be a primary reaction 

 per se. No experiments have been carried out as yet to settle this point. 

 Gentner and Schwerin (23), by counting particles in a pseudoglobulin 

 solution under the ultramicroscope, found that, as radiation time X inten- 

 sity increased, the rate of precipitation increased somewhat and the 

 latent period decreased a great deal (see Fig. 3, a). They found also 

 that if two equal values of radiation X intensity are compared, the 

 greater intensity X the shorter time resulted in a greater rate of precipita- 

 tion and a shorter latent period (see Fig. 3, h). Therefore it^ = const. 



120 



o 80 

 fe 60 

 S5 40 



£ 20 



z 



Time,Minu+es 



120 



too 



-S 80 



1. 

 eg 



60 



40 



E 



D 



z 20 



20 



25 



5 10 15 



Time, Minu+es 



Fig. 3. — Number of particles visible in the field of the ultramicroscope a given time 

 after radiation, a. (Upper diagram) : Number at head of each curve = product it (radiation 

 intensity X radiation time) . h. (Lower diagram) : The product ii = same but in curve 

 1 = large intensity for a short time and in curve 2 = small intensity for a long time. 

 (After Gentner and Schwerin Strahlenth. 37 : 788. 19.30.) 



(p being less than 1 for the elTect of ultra-violet light on protein solutions). 

 Observations of this type, however, measure the rate of aggregation of 

 the denatured protein particles, not the rate of denaturation. The 

 aggregation is certainly a secondary hght reaction, but the denaturation 

 itself, which precedes aggregation, may be a primary light reaction. 

 Experiments to investigate this point are highly desirable. (See foot- 

 note*, page 319.) 



The nature of the physicochemical change taking place in protein 

 molecules, which results in denaturation, has not been solved. The 

 evidence so far indicates no change in molecular size, the aggregation 

 being probably a secondary phenomenon. It has been suggested (42) 



