SELECTED PAPERS 



antithesis between the aerobic and anaerobic mode of life has been 

 largely removed. 



The question now arises in how far three decades of biochemical 

 investigations which have added so much to our insight into microbial 

 catabolism have also succeeded in elucidating the anabolic counter- 

 part of metabolism. Even a superficial survey of anabolism suffices to 

 recognize that the task of the biochemist in this respect is tremendous. 

 The building up of the thousands of chemically widely differing cell 

 constituents starting from the compounds of the food is especially in 

 the microbe world an extremely impressive problem, for numerous 

 are the instances in which microbes are performing this miracle in 

 media in which the number of the organic constituents is restricted to 

 one or two. This obviously means that proliferation of a micro-organ- 

 ism in such a medium involves a super-chemistry far beyond the imag- 

 ination of the boldest and cleverest of our organic chemists. 



Nevertheless we may state that in this domain too real progress has 

 been made in the period under consideration. Much of this progress 

 is closely linked up with the advances made regarding our knowledge 

 of catabolic processes. This becomes at once clear when we first con- 

 sider what may be called the main aspect of anabolism. 



Thirty years ago the view was generally held that in anabolism we 

 are dealing with a very special type of chemistry. For it is of common 

 experience that in these anabolic processes often compounds are form- 

 ed with an energy content which greatly surpasses that of the substrate 

 of the synthesis. I need only remind you of the formation of fat by cells 

 which develop in a medium with sugars as a sole source of carbon. 

 Hence it was concluded that in anabolic processes we were dealing 

 with reactions of a very special kind unknown in ordinary che- 

 mistry, so-called involuntary reactions, in which the free energy of 

 the system increases. This was deemed possible because these re- 

 actions acquire energy from the simultaneously occurring catabolic 

 processes in which the free energy decreases, and this to such an 

 extent that the free energy of the complex system as a whole, de- 

 creases as well. 



It is easily understood that gradually much opposition has devel- 

 oped against this conception of an energetic coupling of two chemical 

 reactions which do not have any material link in common. It is, there- 

 fore, most rejoicing that in the last ten years considerations have been 



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