124 PTEROYLGLUTAMIC ACID 



Weygand et al.^'' described a new synthesis of PGA by the reaction of 

 the condensation j^roducts of 7>-tolyl-D-isoglucosamine and sugars, with 

 6-hydroxy-2 ,4 , 5-triaminopyrimidine. Later Weygand and Schmied-Kowar- 

 zik^" described a series of syntheses of PGA by other reactions. 



Kirsanova and Trufanov^^ described the synthesis of PGA by reaction of 

 p-aminobenzoyl-D(l)-gliitamic acid, 2,3-dibromopropionaldehyde, and 

 2,4,0-triamino-O-hydroxypyrimidine. This synthesis is similar to that re- 

 ported by Angier^ and others. They described an improved purification 

 process by which there was no loss in activity, whereas the method of 

 Angier^ involved a loss of 85 % or more. 



Hultquist and Dreisbach^^ have patented a method for the synthesis of 

 PGA. 



Haehner et al.^^ reported PGA synthesis by condensing 2-amino-5,5- 

 dibromobarbituric acid with p-[2,3-diaminopropyl)amino] benzoyl glutamic 

 acid to give an imstable intermediate product which rearranged to dihydro 

 PGA. On oxidation it gave a good yield of relatively pure PGA. 



Petering and Schmitt^** have patented methods for synthesizing 2,4- 

 diamino-6-(3-carboxy-l ,2,3-trihydroxypropyl)pteridine and 2-amino-4- 

 hydroxy-6-(3-carboxy-l ,2 ,3-trihydroxypropyl)pterines. 



Merck and Co.^^ and Parke, Davis & Co.^^ have patented other methods 

 for synthesizing this vitamin. 



IV. Biochemical Systems 



E. L. R. STOKSTAD 

 A. COENZYMES AND ENZYMES 



The primary biochemical role of PGA appears to be the synthesis of 

 compounds such as purines, pyrimidines, and certain amino acids which 

 involve the incorporation of a single carbon fragment. 



1. Function of PGA in Synthp:sis of Purines and Pyrimidines 



The relationship between PGA and purines in the nutrition of lactic acid 

 organisms was noted early in the work on this vitamin. Snell and Mitchell' 



"F. Weygand, A. Wacker, and V. Schmied-Kowarzik, Chcm. Ber. 82, 25 (1940). 

 i« F. Weygand and V. Schmied-Kowarzik, Chem. Ber. 82, 333 (1949). 

 1' V. A. Kirsanova and A. V. Trufanov, Biokhimiya 14, 413 (1949). 



18 M. E. Hultquist and P. F. Dreisbach, British Pat. 657,831 (1951). 



19 E. Haehner, H. Nafziger, and H. Ludes, Klin. Wochschr. 29, 571 (1951). 



20 H. G. Petering and J. A. Schmitt, U. S. Pats. 2,568,482, 2,568,684 (1951). 



21 Merck and Co., U. S. Pat. 2,540,274 (1951); British Pat. 653,068 (1951). 



22 Parke, Davis & Co., U. S. Pat. 2,476,360 (1949); British Pat. 639,154 (1950). 

 1 E. E. Snell and H. K. Mitcliell, Proc. Natl. Acad. Sci. U. S. 27, 1 (1941). 



