483 



Pyridines 



COOH' 



^N 

 H 



Dihydro- 

 nicotinic Acid 



COOH 



H2 



Nicotinic 

 Acid 



A different method of biosynthesis exists in Escherichia 

 coli and Bacillus suhtilis since tryptophan is not used. In- 

 vestigation of this route has not progressed so far, but 

 glycerol is capable of supplying all carbon atoms, as are 

 glyceric acid and dihydroxy acetone (but not pyruvate). 

 Succinate, malate, fumarate and oxaloacetate also were 

 used. Ribose and adenine were required, which suggests 

 direct synthesis of the coenzyme. ^^ 



^' Manuel V. Ortega and Gene M. Brown, /. Am. Chem. Soc. 81 

 4437 (1959). 



