OCCURRENCE 



10. B. L. Hutchings, E. L. R. Stokstad, J. H. Boothe. J. H. Mowat, 



C. W. Waller, R. B. Angier, J. Semb and Y. SubbaRow, /. Biol. 

 Chem., 1947, 168, 705. 



11. A. J. Glazko and L. M. Wolf, Arch. Biochem., 1949, 21, 241. 



12. V. Allfrey, L. J. Teply, C. GefEen and C. G. King, /. Biol. Chem., 



1949, 178, 465. 

 13- W. J. Mader and H. A. Frediani, Anal. Chem., 1948, 12, 1199. 



8. OCCURRENCE OF FOLIC ACID COMPLEX 



Folic acid has been reported to be present ^ in liver, kidney, yeast, 

 mushrooms, grass and other green leaves. 



Milk has a very low folic acid content, although A. D. Welch and 

 L. D. Wright ^ failed to produce folic acid deficiency in rats when a 

 milk diet was used in conjunction with a poorly-absorbed sulphon- 

 amide such as succinylsulphathiazole. Moreover, the hepatic tissues 

 of such rats were found to contain more microbiologically active 

 material than the livers of rats fed a purified diet supplemented with a 

 comparable amoimt of folic acid. Welch and Wright suggested that 

 milk contained a substance, itself microbiologically inactive, which 

 served as a growth factor for rats. The presence of a conjugated form 

 of folic acid was, in fact, confirmed by A. Z. Hodson,^^ who assayed 

 milk microbiologically after digestion with chick pancreas conjugase. 

 Unfortunately inconsistent results were obtained with different test- 

 organisms, L. helveticus giving a value of 11 to 74 /xg. per g. and S. 

 faecalis a value of 0-9 to 2-4 /xg. per g. ; still higher results were obtained 

 by a chick assay method. In spite of these inconsistencies, the results 

 explain the observation of Cooperman et al.^ that milk is a good 

 source of the monkey anaemia factor. Most of this was present in 

 the skim milk and hardly any in the cream ; raw whey was also a 

 good source of the factor. Milk, as well as liver and certain grains, 

 were good sources of the SLR factor, but leafy materials were, in 

 general, poor sources of both.* Good correlation was observed 

 between the effect of crude preparations on anaemic monkeys and 

 their effect on S. faecalis R, but correlation was less satisfactory with 

 purified materials. 



Folic acid is also present ^ in many micro-organisms, the highest 

 yields (0-25 to 1-67 mg. per ml.) being obtained from B. suhtilis, B. 

 vulgatus, Serratia marcescens and a Gram-negative bacillus from chick 

 intestine. 



The amount of monkey anti-anaemia factor ^ in fresh liver was 

 greater than in whole liver powder, but lyophilised liver retained the 

 total amount present in the fresh liver. Beef and pork livers were 

 equally potent. 



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