Significance of Molecular Hydrogen 



Metabolism in the Transitionary Stage 



fi:om Anaerobiosis to Aerobiosis 



YOSHIHARU ODA 



The Institute for Agricultural Research, Tohoku University, Sendai, Japan 



INTRODUCTION 

 It is customary, when considering the chemical reactions which occur in Hving 

 beings, to remark upon their versatility, their complexity, and that virtually 

 all of them are catalytically induced by agents we call enzymes. As far as we 

 know, enzymes are catalytic proteins. 



To say that they are all proteins is perhaps a generaHzation, and some of them 

 have now been isolated in the pure crystaUine state. It has also been possible to 

 build up trains or chains of enzyme reactions which reproduce in vitro some of 

 the metabolic processes which occur in living beings. 



But in the hving beings, these enzyme systems do not function at random, 

 but co-operate to bring about an organized chain of successive reactions, all 

 directed to accompHshing the metaboHc processes. It is fundamentally important 

 to throw Hght on the organization and co-ordination of the enzyme systems in 

 order to advance our understanding of this exceedingly dynamic aspect of the 

 life process. But there has been a tendency that the organizing potentiaHties 

 inherent in highly specific catalysts, enzymes, have not been adequately ap- 

 praised in chemical thought. 



We recently studied the problems of enzymic adaptation in micro-organisms 

 to understand the dynamic mode and nature of enzyme systems in the Hving 

 cells. In our studies [i, 2], it was found that control of events by intracellular 

 enzymes in the hving cell secures the status of the cell as a system which can 

 maintain itself in dynamic equihbrium with its envirormient. 



Here, the following question arises: how might the interrelated activity of 

 enzyme systems with their environment — organization and co-ordination — have 

 developed in the Hfe process ? In this connection, the activity of highly specific 

 catalysts is a property left in the fine of evolution and represents a notable device 

 of Nature which has supported during the long course of biological evolution 

 those dynamic manifestations which characterize living things. One of the basic 

 problems of the activity of enzyme systems is the historical course of its 

 development. 



From the above standpoint, we have studied the significance of molecular 

 hydrogen metaboHsm for comparative physiology for several years. A survey 

 of the occurrence of hydrogen metaboHsm in micro-organisms discloses that 



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