NICOTINAMIDE NUCLEOTIDE ENZYMES 

 FORMULA 4 



113 



CONH. 



I O^ pR' 

 R-0-P=0 



<- 



■^ 



CONH. 



N' , 



I HO, PP' 

 R-0-P = 



According to Haas this reaction can be controlled manometrically 

 if bicarbonate is present in the medium (25). The attempts of Karrer 

 to synthesize nicotinamide derivatives with pentose as a substituent 

 were not successful. Attempts with arabinose and xylose gave oily 

 products which could not be obtained in a pure nor in a crystalline 

 form. The closest link between the model compounds and the co- 

 enzymes, therefore, was missing. The compound consisting of nico- 

 tinamide and pentose has been obtained from cozymase (26). It 

 possesses all the expected properties and has some biological in- 

 terest. Since no extensive publication on this subject has yet ap- 

 peared, the preparation and properties of the compound are here 

 discussed in somewhat more detail. 



As has been pointed out, the splitting of the linkage between 

 nicotinamide and pentose is the first result of acid as well as of 

 alkaline hydrolysis of cozymase. Therefore only enzymatic splitting 

 could yield this very labile nucleoside. For this purpose the nucleo- 

 tidase discovered by Bredereck in sweet almond press-cake was 

 chosen (27). After purification this enzyme has the following prop- 

 erties, which make it suitable for the preparation of the nucleoside: 

 The pH for optimum activity is about the same as that for the 

 optimum stability of cozymase. The preparations are free from 



Table 5.— Enzymatic splitting of cozymase 



A fresh enzyme was added after 96 hours. 



