SELECTED PAPERS 



phosphoglycerylphosphate (diphosphoglyceric acid). The important 

 aspect of this observation is that this oxidation is reversible while the 

 analogous oxidation of the phosphotriose without phosphate is strong- 

 ly exergonic. We may conclude, therefore, that the diphosphoglyceric 

 acid, owing to the energy-rich acylphosphate bond acts as a storage 

 for the potential energy of the oxidation reaction. Both Lipmann and 

 Kalckar have in recent years discovered several other labile com- 

 pounds with such energy-rich phosphate bonds, and have dealt in 

 theoretically very important studies with their remarkable properties. 

 There seems to be little doubt that these highly reactive compounds 

 with high energy potential which are formed in catabolic processes 

 act as a starting point for synthetical processes which then again con- 

 sist of chains of ordinary step-reactions, i.e., reactions which proceed 

 with a decrease of free energy. 



A striking example in favour of this view may not pass unmentioned. 

 I have already referred to the remarkable metabolism of the so-called 

 chemo-autotrophic bacteria who are able to build up their cell con- 

 stituents from carbon dioxide owing to the energy derived from in- 

 organic oxidation processes. Until shortly the nature of this energy 

 transfer was still wholly obscure. Vogler, Umbreit and Le Page have 

 now given convincing proof that for the sulphur oxidizing bacterium 

 Thiobacillus thiooxidans the formation of organic phosphate compounds 

 provides a material link between catabolism and anabolism. The first 

 advance made by these investigators was the demonstration of the 

 possibility to separate both processes in time. A suspension of the bac- 

 teria supplied with a small quantity of sulphur in the absence of carbon 

 dioxide was found to consume oxygen rapidly, and if then after some 

 time carbon dioxide was admitted a rapid uptake of this gas was ob- 

 served. But the most remarkable fact was that the oxidation of the 

 sulphur proved to be accompanied by the uptake of inorganic phos- 

 phate from the medium, whilst in the phase of carbon dioxide assim- 

 ilation the phosphate was again released. Finally it could be shown 

 that the cells contained several organic phosphate compounds well- 

 known as metabolites in heterotrophic organisms. The intermediate 

 organic phosphate compound which evidently acts as a material link 

 between the energy yielding oxidation and the energy demanding syn- 

 thesis is to all probability adenosine-3-triphosphate a compound close- 

 ly related to adenosine-5-triphosphate, a regularly occurring inter- 



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