STUDIES ON THE MECHANISM OF RADIATION 



PROTECTION AND RECOVERY WITH 



CYSTEAMINE AND P-MERCAPTOETHANOL * 



Alexander Hollaender and C. O. Doudney 

 Biology Division, Oak Ridge National Laboratory, Tennessee 



I N an effort to elucidate the mechanism involved in the protection of living 

 material from X- and gamma radiation, a comparison was made of the 

 protective efficiency of cysteamine (p-mercaptoethylamine) and ^-mercapto- 

 ethanol on Escherichia coli B/r. The latter compound was chosen for study 



1-0 



Molar concn. of cysteamine 

 0-002 0006 001 0-02 



om 



"I — I — r 



Cysfeamtne 



p-mercapfoef Hanoi 



Figure 1. The effect of cysteamine and 



fj-mercaptoethanol on the survival of E. coli 



Bjr during exposure to 60 kr of 250-kVp 



X-rays 



0-025 0-05 0-095 0-1 



Molar concn. of ji-mercaptoethanol 



because it resembles cysteamine very closely in structure and in chemical 

 properties. 



The effect of concentration on protection against X-ray damage to 

 E. coli B/r at 60 kr for these two compounds is depicted in Figure 1 (upper 

 scale, cysteamine ; lower scale, mercaptoethanol). Cysteamine reaches its 

 maximum protective level at • 006 M, and the plateau for mercaptoethanol 

 is about • 1 M. 



* Work performed under Contract No. W-7405-eng-26 for the U.S. Atomic Energy 

 Commission. 



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