The Role of Carbohydrates 



in the Biosynthesis 



of Aromatic Compounds 



DAVID B. SPRINSON 



The diversity and importance of aromatic compounds in biological 

 materials, from simple hydrocarbons to complex alkaloids, have been 

 responsible for several theories of their biogenesis on the basis of struc- 

 tural relationships or known laboratory reactions. Direct experimen- 

 tal attack on this problem began with the discovery by B. D. Davis 

 in 1950 that shikimic acid (SA) is an intermediate in the formation 

 of the aromatic amino acids 1 in certain nutritionally deficient mutants 

 of Escherichia coli. 



The studies on the formation of tyrosine and phenylalanine from 

 labeled compounds 2 ~ 6 do not permit the two sides of the ring to be 

 distinguished from each other, in contrast to those with SA. Accord- 

 ingly, in collaboration with B. D. Davis, 7 methods were developed for 

 the isolation of SA from nitrates of E. coli mutant 83-24, and for its 

 chemical degradation (Fig. 1). It had been observed that, when this 

 organism was grown on a glucose-salts medium with the addition of 

 NaHC 14 3 , HC 14 OONa, acetate, labeled in either carbon atom, or 

 pyruvate-2-C 14 , the activity incorporated into SA from these additions 

 was negligible. The participation of the tricarboxylic acid cycle inter- 

 mediates in the biosynthesis of tyrosine and phenylalanine in yeast 

 had also been excluded by Gilvarg and Bloch, 5 who showed that, al- 

 though labeled acetate, in the presence of glucose, was incorporated 

 into glutamate, aspartate, and alanine, no activity was observed in the 

 aromatic amino acids. 



When glucose labeled in G-l, G-2, G-3, 4, or G-6 * was utilized for 



* The abbreviations S-l, S-2 ••• S-7 will be used to denote carbon atoms 1, 2 

 ••• and carboxyl of sbikimate; and G-l, G-2 •••to denote carbon atoms 1, 2 

 • • • of glucose. 



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