V. HIOGKNESIS 



i; 



Phloroiihiciiiol has been implicated l)y Shive" as a possible intermediate 

 ill the biogenesis of the aromatic riiiji;. These studies involved a system w here 

 a strain of LcuconoHtoc mcscntcroidcs that recjiiires pantothenic acid and 

 either acetate or aromatic amino acids for j^rowth is inhibited by dl-N- 

 pantoyl-/t-butylamine. Pantothenic acid reverses the inhibitor with an 

 index of about .SOO in the |)resence of acetate. In the presence of phenylala- 

 nine, tryptophan, or tyrosine the inhibition index is increasetl to 3()(K). 

 Phloroglucinol, particularly in tlie presence of increased phosphate, is just 

 as effective as the aromatic amino acids. These data were interpreted to 

 indicate that pantothenic acid functions in the conversion of acetate to an 

 intermediate, such as phloroglucinol, common to the biogenesis of the aro- 



H OH 



Quinic acid 



(l,3,4,5-tetrahydro.\y- 



cyclohexanecarboxylic acid) 



-SH.Q 



COOH 



I 

 OH 



p-Hydroxybenzoic acid 



-3H2O 



H OH 



Inositol 



HO 



HO 

 Phloroglucinol 



matic amino acids and presumably of PABA. Phloroglucinol is inacti\e in 

 promoting growth of certain Escherichia coU mutants-^ with a nutritive re- 

 (luirement for aromatic amino acids. 



A scheme for the synthesis of aromatic compounds, including PABA, 

 has been ad\-anced by Davis^ as a result of the study of a variety of mutants 

 of Escherichia coli selected by the penicillin method.^-^ Mutants were ob- 

 tained in this manner with reciuirements for two or more of the aromatic 

 compounds tyrosine, phenylalanine, tryptophan, and PABA. For certain 

 mutants with a re(iuirement for the above four aromatic compounds, shi- 

 kimic acid was found to duplicate the growth-promoting effect of a combina- 



«W. Shive, Ann. A'. 1'. Acad. Sci. 52, 1212 (1950); M. Gordon, Ph.D. Thesis, 



versity of Texas, 1948. 

 ^ B. D. Davis, J. Am. ('hem. Soc. 70, 4267 (1948). 

 s H. D. Davis, Proc. A'all. Acad. Sci. U.S. 35, 1 (1949). 

 ' J. Lederbers and N. Zinder, J. Am. Chem. Soc. 70, 4267 (194S). 



