100 AARON BENDICH 



as well as of divicine was present as free amino groups, one of which was 

 part of a guanidino system, and he concluded that vicine was a 3-iV-gluco- 

 side of 2 ,5-diamino-4 ,6-dihydroxypyrimidine. Recent evidence^^^ has shown 

 this widely accepted formulation to be incorrect. Vicine was assigned the 

 structure XXIX (i.e., 2,4-diamino-6-hydroxy-5-(jS-D-glucopyranoside)) and 

 divicine that of 2,4-diamino-5,6-dihydroxypyrimidine (XXX) on the 

 basis of a study of ultraviolet absorption spectra and a variety of chemical 

 properties.2'3.214 Divicine belongs to a group of pyrimidines and other com- 

 pounds (such as ascorbic acid) that contain an enediol, aminoenol, or 

 amino-eneamine system conjugated to a carbonyl (or potential carbonyl) 

 group and therefore possess strong reducing properties ;^'^ vicine is non- 

 reducing. A similar substance, convicine (C]oH]608N3-H20), accompanies 

 vicine in viaa.^'^^ie Convicine is believed to be a hexoside of 4-amino-2 , 5 , 6- 

 trihydroxypyrimidine,2'7 and its chemical properties^'^-^'^ indicate that this 

 glycoside is very closely related to vicine in structure. 



A compound of increasing interest and importance, orotic acid^'^ (XXXI, 

 or uracil-4-carboxylic acid) was discovered in the whey of cow's milk by 

 Biscaro and Belloni^^^ in 1905; the name is derived from the Greek: oros = 

 whey. It is found in the milk of sheep and goats, and in smaller amounts 

 in human, pig, and horse milk,22o-222 and has been isolated from "distillers 

 dried solubles. "^^s Orotic acid accumulates in large quantities during the 

 growth of mutants of the fungus Neurospora, which require uridine, cyti- 

 dine, or uracil,22'i and is required for the growth of L. hulgaricus 09.22'''22' 

 For a discussion of the participation of orotic acid in nucleic acid pyrimi- 

 dine biosynthesis see Chapters 23 and 25. A riboside of orotic acid (oroti- 

 dine) has also been isolated^^^ from Neurospora; unlike uridine and cytidine, 



2'3 A. Bendich, Trans. N. Y. Acad. Sci., [2] 15, 58 (1952). 

 2'^ A. Bendich and G. C. Clements, Biochirn. et Biophys. Acta 12, 462 (1953). 

 215 H. Ritthausen, J. prakf. Chem. [2] 24, 202 (1881). 

 2'8 H. Ritthausen and Dr. Preuss, J. prakt. Chem. [2] 59, 489 (1899). 

 2" H. J. Fischer and T. B. Johnson, J. Am. Chem. Soc. 54, 2038 (1932). 

 218 Beilstein, 26, 253 (1936). 



"9 G. Biscaro and E. Belloni, Ann. Soc. Chim. Milano 11, 18, 71 (1905) ; a fairly detailed 

 account of this work given in Chem. Centr. II, 76, 63 (1905). 



220 O. p. Wieland, J. Avener, E. M. Boggiano, N. Bohonos, B. L. Hatchings, and J. H. 

 Williams, /. Biol. Chem. 186, 737 (1950). 



221 J. W. Huff, D. K. Bosshardt, L. D. Wright, D. S. Spicer, K. A. Valentik, and H. R. 

 Skeggs, Proc. Soc. Exptl. Biol. Med. 75, 297 (1950); see also /. Arn. Chem. Soc. 72, 

 2312 (1950). 



222 L. E. Hallanger, J. W. Laasko, and M. O. Schultze, /. Biol. Chem. 202, 83 (1953). 



223 L. Manna and S. M. Hauge, /. Biol. Chem. 202, 91 (1953). 



22" H. K. Mitchell, M. B. Houlahan, and J. F. Nye, J. Biol. Chem. 172, 525 (1948). 

 226 A. M. Michelson, W. Drell, and H. K. Mitchell, Proc. Nail. Acad. Sci. U. S. 37, 396 

 (1951). 



