86 



ENZYME AND RELATED EFFECTS IN 

 THE INTACT CELL 



Kenneth P. DuBois 



During the course of the previous discussions, numerous approaches 

 to the problem of the mechanism of action of high energy radiations have been 

 explored. These have included investigations of the effects of radiations on 

 crystalline compounds, on solutions or suspensions of biologically, important 

 materials, and on intact microorganisms, plants, and aninnals. . 



All of the approaches have contributed a great deal to our knowledge 

 of the biological actions of ionizing radiations but, thus far, conclusive evi- 

 dence for any theory or explanation of radiation damage in the intact animal is 

 lacking. 



As the accumulation of knowledge regarding the action of ionizing ra- 

 diations on organ systems and on intact cells has progressed, greater interest 

 has been manifested in the biochemical mechanisms that may be involved in the 

 production of the injurious effects. Several phases of biochemistry have been 

 investigated in connection with the mode of action of ionizing radiations. The 

 possibility that disturbances in enzyme systems alter the functional activity and 

 subsequently the morphology of irradiated cells has also received considerable 

 attention. 



Although radiation effects on enzyme systems are only partially eluci- 

 dated, a sufficient amount of research has been done to permit a general dis- 

 cussion of the extent to which enzyme action is interrupted in radiation-injured 

 cells. 



It is hoped that the particular areas of enzymology that have been stud- 

 ied sufficiently with respect to radiation damage as well as those that have been 

 neglected can be recognized from our discussion this afternoon. 



Many studies have been carried out on the influence of high energy ra- 

 diations on chemical compounds in vitro and have provided an indication of the 

 relative susceptibility of various compounds to alteration by irradiation. Among 

 the earliest studies were experiments of the type performed by Fricke and Hart 

 (1) in which simple organic compounds were employed. One of the valuable con- 

 tributions resulting from these studies was the observation that the addition of 

 various substances to aqueous solutions of a compound could protect the com- 

 pound from decomposition by irradiation. This finding is particularly noteworthy 

 to the biochemist in his consideration of the effects of irradiation, since a simi- 



