479 Pyridines 



Claviceps purpurea (Fries) Tul. 



A. Stoll, A. Hofmann and Th. Petzilka, Helv. Chim. Acta 

 34 1544 (1951). (Structure) 



i. PYRIDINES 



Few pyridines are listed, but two of these, nicotinic acid 

 and pyridoxine, are vitamins. Fusaric acid is a wilt toxin, 

 and 2,6-dipicolinic acid appears in conspicuous quantities 

 in bacterial spores. 



Dipicolinic acid' - ' ' probably is formed by cyclization 

 of ci;,€-diaminopimelic acid, a lysine precursor and cell wall 

 constituent of some bacteria: 



HOOC — k J — COOH /^^,, 

 NH> NH.. / N' 



HOOC COOH 



Diaminopimelic Acid 2,6-Dipicolinic Acid 



The metaboHc significance, if any, is unknown. In Bacil- 

 lus sphaericus diaminopimelic acid is present in spores 

 and not in vegetative cells, but in many bacteria it is pres- 

 ent in both. 



Fusaric and dehydrofusaric acids are by-products of the 

 gibberellin fermentation and are produced by fusarium 

 types. These include plant pathogens, and fusaric acid 

 solutions sprayed on healthy plants of the usual host 

 cause wilting typical of infection. Apparently no study 

 has been made of the mode of biogenesis. 



Nicotinic acid in its coenzyme forms occurs in all living 

 cells where it is essential in hydrogen and electron trans- 

 port. It is used by a variety of apoenzymes as the pros- 

 thetic group for various dehydrogenase reactions. It is 

 much less tightly bound to the protein than, for example, 

 flavine adenine dinucleotide, perhaps to facilitate move- 

 ment of the available supply among the apoenzymes in 

 need of it. 



Some of the many microbial reactions known to require 

 diphosphopyridine nucleotide (DPN) or triphosphopyri- 

 dine nucleotide (TPN) are: 



1 Joan F. Powell, Biochem. ]. 54 210 (1953). 



-J. J. Perry and J. W. Foster, J. Bacteriol. 72 295 (1956). 



■^ William K. Harrell and Emil Mantini, Can. J. Microbiol. 3 735 

 (1957). 



^ Joan F. Powell and R. E. Strange, Biochem. J. 65 700 (1957). 



