^-AMINOBENZOIC ACID 



Subsequently they ^ debcribed a method of assaying ^-aminobenzoic 

 acid in a variety of foodstuffs and animal tissues by means of a mutant 

 of Nenrospora crassa. The use of yet another organism, Clostridium 

 acetobutylicum, was proposed by J. O. Lampen and W. H. Peterson,^ 

 who recommended alkaline hydrolysis for the liberation of _/)-amino- 

 benzoic acid. CI. acetobutylicum had the advantage of requiring an 

 incubation time of only twenty to twenty-fo ar hours, and was capable 

 of estimating dilutions of ^-aminobenzoic acid as low as 0-00004 H-S- 

 per ml.^^ 



References to Section 5 



1. H. Tauber and S. Laufer, /. Amer. Chem. Soc, 1941, 63, 1488. 



2. E. R. Kirch and O. Bergeim, /. Biol. Chem., 1943, 148, 445. 



3. H. W. Eckert, ibid., 197. 



4. M. E. Martin and M. W. Green, Bull. Nat. Formulary Comm., 1947, 



16, 106. 



5. M. Landy and D. M. Dicken, /. Biol. Chem., 1942, 146, 109. 



6. J. C. Lewis, ibid., 441. 



7. H. K. Mitchell, E. R. Isbell and R. C. Thompson, ibid., 1943, 147, 



485. 



8. R. C. Thompson, E. R. Isbell and H. K. Mitchell, ibid., 1943, 148, 



281. 



9. J. O. Lampen and W. H. Peterson, ibid., 1944, 153, 193. 



10. R. D. Housewright and S. A. Koser, /. Infect. Dis., 1944, 75, 113. 



4. OCCURRENCE OF p-A2VUNOBENZOIC ACID IN 

 FOODSTUFFS 



The occurrence of ^-aminobenzoic acid in foodstuffs is obviously 

 correlated to some extent with the occurrence of folic acid (page 483) 

 but, whereas an estimate of the total {free and combined) _^-amino- 

 benzoic acid would include any ^-aminobenzoic acid present as folic 

 acid, ^-aminobenzoic acid occurs in foodstuffs in the free state and in 

 compounds other than folic acid. It has already been stated, for 

 example (page 548), that in yeast 20 to 30 % of the ^-aminobenzoic 

 acid is present in combination with a polypeptide of glutamic acid. 



A limited amount of information is available concerning the 

 ^-aminobenzoic acid contents of foodstuffs ; these invariably contain 

 appreciably more ^-aminobenzoic acid than the amount equivalent 

 to the folic acid present. 



The following values were obtained for cereals : wheat germ, 

 i-o ; ^ wheat middlings, 0-52 ; ^ oats, 0-5 ; ^ rolled oats, 0-33 ; ^ 

 maize meal, 0-3 ; ^ and alfalfa meal, 2-0 /xg. per g.^ 



Fresh spinach contained 0-6 ; ^ dried carrots, o-i8 ; ^ and dried 

 cabbage, 97 /xg. per g.* 



550 



