I. NOMENCLATURE AND FORMULA 89 



I. Nomenclature and Formula 



E. L. R. STOKSTAD* 



There are few examples in biochemistry where a siiifj;l(» oompound has 

 provided the key to as many nutritional phenomena as has ])terovlghitamic 

 acid. Deficieiuy states of tliis vitamin ha(ll)een described in man, monkeys, 

 chicks, rats, guinea pigs, insects, and microorganisms before pteroylglu- 

 tamic acid was identified and its structure determined. 



In view of the many phases of biological work already in progress by the 

 time pteroylglutamic acid was synthesized and made available, it is not 

 surprising that a large number of papers soon appeared on its role in clinical 

 medicine, animal nutrition, bacterial metabolism, enzyme chemistry, and 

 tumor research. 



Since work on this vitamin has proceeded independently in many labora- 

 tories employing different species, the literature is replete with the various 

 names used to designate it. A summary of the names which have been 

 given to various biologically active materials whose activity can be ascribed 

 to pteroylglutamic acid is presented in Table I. 



The nomenclature in this field is also complicated by the existence of 

 different chemical forms which were subsequently shown to be conjugates 

 of the vitamin with varying numbers of glutamic acid residues. Thus the 

 name "fermentation L. casei factor" was given to a compound isolated 

 from a fermentation product and which later was shown to be pteroyltri- 

 ghitamic acid. The name "vitamin Be conjugate" was used to designate 

 the compound isolated from j^east and which was shown to contain seven 

 glutamic acid residues. This will be referred to as pteroylheptaglutamic 

 acid. The name "folic acid" has found the most universal acceptance, 

 largely because of its brevity. The term "folacin," recommended bj^ a joint 

 nomenclature committee of the American Institute of Nutrition and the 

 Societj^ of Biological Chemists, has not as yet received wide usage. In this 

 chapter the name pteroylglutamic acid, abbreviated PGA, will be used 

 except in accounts of original literature where the investigator used a 

 .special name to designate a biologically active factor, the exact chemical 

 identity of which cannot be established. 



One of the first published observations describing a clinical syndrome 

 which was the result of PGA deficiency was made by Wills' in 1931. This 

 disease was found to have a blood picture similar to that in pernicious 

 anemia, except that some of the other symptoms, such as achlorhydria and 

 nervous lesions observed in pernicious anemia, were absent. This condition 



* It is a plea.suro to acknowledge the assistance of M. J. Fahrenhacli and If. P. 

 Broquist in writing portions of this review and the services of Carol (lunderson in 

 the preparation of the manuscript. 



