Rothamsted Symposium on Trace Elements 124 



animals. It was found necessary to extend our research from 

 trace elements to other substances in order to acquire an insight 

 into the role of trace elements in metabolism. Obviously, the 

 results do not yet present a complete picture but some of the 

 conclusions seem worth reporting. 



Trace Elements as Bio-Catalyzers of Enzyme Action:— In 



a recent paper we showed that the ions of trace elements may act 

 on metabolic processes in the animal body in two different ways 

 (2). First of all they may be taken up in the molecules of 

 enzymes, vitamins and hormones. These complexes act as bio- 

 catalyzers in the processes of intermediate metabolism. On the 

 other hand, they may act as activators of enzymes and in this way 

 influence metabolic processes. 



A general survey of trace elements acting on enzymes in these 

 two different ways is given in Table 22. 



Two facts should be noted. In many cases an optimum con- 

 centration of minor elements, with regard to the activation of 

 enzyme action, is shown to exist. Evidence has been obtained 

 that a surplus, as well as a deficit of those elements, lowers the 

 tempo of enzyme action. Probably, the latter conditions may be 

 compared with conditions of intoxication and deficiency of trace 

 elements in the animal body. Moreover, the mode of action of 

 trace elements, by means of enzymes, implicates some influence 

 of the pH of body tissues on the action of trace elements in the 

 animal organism (4). 



Table 22 shows that four types of processes of a fundamental 

 importance in normal life are subject to the action of trace 

 elements, viz., (I) the synthesis and destruction of tissue elements 

 (mainly protein), (2) energetic processes (oxi do-reductions), (3) 

 detoxication of poisons of endogenous origin, (4) the regulation 

 of nervous stimuli (2). 



This opens new outlooks on the genesis and therapy of several 

 diseases, e.g., "licking sickness" (pica) in animals, ketonemia in 

 catde, avitaminosis and hypovitaminosis Bi and C, autointoxi- 

 cation in men and animals, and perhaps even on the problem of 

 carcinoma. 



The Distribution of Copper in the Liver and the Blood of 

 Cattle and Horses. Regulation of Copper Metabolism:— 



Experiments with cattle.— The level of copper (and other 



