8 NEUTRON EFFECTS ON ANIMALS 



of equilibrium or \-ital balance and that they are equipped with highly 

 specific catalysts, enzymes, hormones and vitamins which, in selected 

 chemical reactions, determine the course of the metabolic processes. These 

 catalysts in minute amounts are necessary for the continuance of life and 

 more particularly for the synthesis of rapidly growing cells such as the 

 lymphocytes which disappear after severe neutron bombardment. 



In neutron effects, on account of the severity of the result and the quick- 

 ness of action, vitamins and hormones are less likely to be the deficiency 

 because the effect of their lack may not be shown as quickly as the other 

 neutron effects. The neutron effect may be a two-stage or even a three- 

 stage effect; the altering of these substances maj^ prevent the continuance 

 of the metabolic processes. An example of this is the interference with 

 sulfur metabolism so necessary to growing cells, the chief source of which is 

 methionine, biotin, and thiamine. 



The effects of neutrons may be upon one of the enzymes or it may be 

 on the enzyme activator. The substrate may also be affected. 



The enzymes, which are all proteins, are dependent upon their structural 

 elements and there is an active catalytic center to involve the combination 

 of the substrate with the active center of the enzyme to form a dissociable 

 enzyme-substrate complex. The substrate is activated and this activated 

 substrate molecule then undergoes rapid reaction with another substance. 

 Both the catalytic activity and the specificity of its actions depend upon 

 the nature of the protein. 



Attached to the proteins are prosthetic groups, often of low molecular 

 weight, which combine reversibly with specific proteins, and so undergo 

 rapid oxidation-reduction reactions. The prosthetic group is usually a 

 partner in the chemical reaction catalyzed by the enzyme. The active 

 catal,ytic center is made up of the structural elem.ents in the protein with 

 which the prosthetic group combines. The enzymes, catalase and per- 

 oxidase, are each a complex protein in which a prosthetic group, hemin, is 

 linked to a specific protein. In our re.'i'earch, it has been found that after 

 neutron bombardment, catalase is not affected while peroxidase is much 

 reduced, so that in this case at least the effect is not upon the prosthetic 

 group although in the case of c/-amino acid oxidase, the inactivation occurs 

 in the prosthetic group, alloxine adenine nucleotide. 



The prominent reactions of the cell are the processes of hydrolysis and 

 condensation, and of oxidation-reduction. Organic substances may un- 

 dergo other reactions such as amination and deamination, alkylation, etc., 

 and these go on continuously and together. Characteristic of life is the 

 large molecule such as protein, easily destroyed and easily reconstructed. 

 Synthetic reactions require energy for their efforts and so they must be 

 coupled with energy-producing reactions. The steady state, the vital 



