CHEMICAL CONSTITUTION 



5. E. L. R. Stokstad, B. L. Hutchings and Y. SubbaRow, Ann. N.Y. 



Acad. Sci., 1946, 48, 261 ; /. Amer. Chem. Soc, 1948, 70, 3. 



6. B. L. Hutchings, E. L. R. Stokstad, N, Bohonos, N. H. Sloane, 



and Y. SubbaRow, Ann. N.Y. Acad. Sci., 1946, 48, 265 ; /. 

 Amer. Chem. Soc, 1948, 70, i. 



7. B. L. O'Dell and A. G. Hogan, /. Biol. Chem., 1943, 149, 323. 



8. J. J. Pfiffner, S. B. Binkley, E. S. Bloom and B. L. O'Dell, /. 



Amer. Chem. Soc, 1947. 69, 1476. 

 Sa. R. D. Greene, /. Biol. Chem., 1949, 179, 1075. 



9. E, L. Rickes, L. Chaiet and J. C. Keresztesy, /. Amer. Chem. Soc, 



1947, 69, 2749. 

 10. R. W. Simmons and E. R. Norris, /. Biol. Chem., 1941, 140, 

 679. 



3. CHEMICAL CONSTITUTION OF FOLIC ACID 



L. casei Factors 



The first formula to be assigned to a member of the folic acid 

 group was that given by Angier et al.^ to the liver L. casei factor (see 

 page 463). This formula was based on the following evidence. i» 2. 3, 4 

 The fermentation L. casei factor on anaerobic alkaline hydrolysis was 

 converted into the dl-ioiva of the liver L. casei factor, the activity 

 towards L. helveticus (L. casei) decreasing and the activity towards 

 S. faecalis R increasing markedly. At the same time, two moles of 

 ^-amino acid were liberated. When the fermentation factor was 

 hydrolysed under aerobic alkaline conditions, rapid inactivation 

 occiurred and two fractions were formed in equimolar amounts ; the 

 first was highly fluorescent, whilst the second gave a positive test for 

 an aromatic amine. 



The fluorescent compound was a dibasic acid, C7H5N5O3, which on 

 heating lost carbon dioxide to give a monobasic acid. Oxidation of 

 the fluorescent compound with chlorine water, followed by hydrolysis 

 with O'l N-hydrochloric acid, resulted in the formation of guanidine. 

 This fact, together with the ultra-violet absorption spectrum, fluor- 

 escence and other properties, suggested the presence of a 2-amino- 

 pteridine derivative containing a hydroxyl and a carboxyl group. 



The compound was shown to be 2-amino-4-hydroxypteridine-6- 

 carboxylic acid by comparison with a synthetic specimen, prepared 

 by the chlorination with phosphorus pentachloride of 2-amino-4 : 7- 

 dihydroxypteridine-6-carboxylic acid,^ followed by reduction with 

 hydrogen iodide. The position of the unchanged hydroxyl group 

 was established by decarboxylation and identification of the product 

 as 2-amino-4-hydroxy-pteridine by comparison with a specimen 



471 



