DISCUSSION 



4 Lea, D. E. and Salaman, M. H. Proc. roy. Soc. 1946, 133 B 434. 



5 Ebert, M., 1954. This Conference. 



* Alper, T. ' Radiation Chemistry,' General Discussions Faraday Soc. 1952, No. 12 



234 

 ' Alper, T. Abstracts, VI. International Microbiology Congress, Rome, Riassunti delle 



Commmica-ione, 1953, 2 No. 528, 181. 



8 Alper, T. Brit. J. Radiol. 1954, 27 50. 



9 Ebert, M. and Alper, T. Nature, Lond. 1954, 173 987. 



10 Weiss, J. Nature, Lond. 1950, 165 728. 



11 CouLSON, C. A. Proc. roy. Soc. 1952, 211A 396. 



DISCUSSION 



L. K. Mee : Alper has mentioned the work of Anderson and McDonald on the 

 continued inactivation of pepsin and trypsin after irradiation. They had shown 

 that this 'after effect' is dependent on temperature. 



We have noticed a similar effect on the normally thermostable enzyme ribonuclease. 

 When irradiated enzyme solutions are kept at O'^C very little further inactivation 

 occurs, but at 25° C and higher temperatures the enzyme continues to lose activity. 

 The continued inactivation appears to be faster at higher temperatures. No inacti- 

 vation of the enzyme has been detected when irradiated solution is added to the 

 unirradiated enzyme. 



This slow reaction appears to depend on a change in the protein during irradiation 

 which does not affect its enzymic activity immediately but makes it unstable in 

 some way. 



45 



