APPLICATIONS OF ISOTOPIC IXDICATORS 951 



place, but active phosphate was detected in the Harden-Young ester 

 formed during alcohohc fermentation. 



In a study of the interaction of labelled adenosine triphosphoric acid 

 with non-labelled hexose monophosphoric acid ester, which leads to 

 the formation of fructose 1.6-diphosphoric acid ester, the labelled phos- 

 phate given off by the adenosine triphosphoric acid was found to be 

 exclusively present in the fructose 1.6-diphosphoric ester. The fact that 

 the free phosphate formed according to the equation: 



adenosine triphosphoric acid -|- hexose 6-monophosphoric ester -\- HgO 

 -> fructose 1.6-diphosphoric ester -f- adenylic acid + phosphate 



was found to be inactive, indicates that the free phosphate originated 

 exclusively from the hexose 6-monophosphoric ester^^^\ 



When both hydrogen and labelled phosphate were transferred, neither 

 of the two stable radicals of the cozymase molecule was found to be 

 replaced by active phosphate. A similar negative result was obtained 

 for the reaction 



3-phosphoglyceric acid — >- 2-phosphoglyceric acid 



in the presence of active phosphate and also for the conversion of glucose 

 monophosphoric acid into glucose hexosephosphoric acid in the presence 

 of active phosphate. The ester fraction were found not to have taken 



up 32P/0) 



Does a less pronounced formation of new molecules take place simul- 

 taneously with the autolysis observed in tissue slices? By the employ- 

 ment of isotopic indicators this question can be answered. On shaking 

 liver, kidney or brain slices for a few hours with a Ringer solution 

 containing ^^p at 37° C, Chaikoff and his colleagues'"^^ found that the 

 phosphatides isolated from the tissue slices contained ^^P; hence, side 

 by side with an autolysis of the phosphatides in the tissue slices, an 

 appreciable formation of labelled phosphatides also takes place. 



The formation of labelled nucleic acid in slices of Jensen's rat sar- 

 coma was likewise obtained''^"' in the investigation of the formation of 

 desoxyribose nucleic acid i7i vitro, when these slices were shaken with 

 labelled blood or labelled Ringer solution. About 0.1 per cent of the 

 desoxyribose nucleic acid molecules present in the tissue slices were 

 found to be labelled after the lapse of 4 hours; these molecules had 

 accordingly been formed during the experiment. The presence of cyanide, 

 hydrogen sulphide, azide or carbon monoxide inhibits the formation 

 of labelled phosphatides. Addition of cyanide, fluoride or monoiodo- 

 acetate to labelled blood or labelled Ringer solution is also found to 

 inhibit the formation of labelled nucleic acid. 



