IV. HIOCHEMICAL SYSTEMS 241 



(hf low content of .serum to a redisli-ihution of the en/,ynu> between blood 

 and other tissues. 



(). Ascorbic Acid and Carbohydrate Metabolism 



There liave been many leport.s of some connection between ascorbic acid 

 and the metabohsm of ('arl)oliydrate. The capacity for metabolizing glucose 

 is loweretl in the scorbutic guinea pig,'^' and these animals show a diabetic 

 type of response to glucose tolerance tests. It has also been reported that 

 scorbutic guinea pigs show lower liver glycogen, glycosuria, and a reduced 

 insulin content of the pancreas compared with normal animals.'"- The 

 ol)servation that dehydroascorbic acid has a diabetogenic effect in rats'^' is 

 in line with these earlier observations. Furthermore, suggestive evidence 

 that the synthesis of glycogen may be connected with ascor})ic acid has 

 been obtained^^^ in experiments showing that the increase in liver glycogen 

 which occurs in normal fasting guinea pigs following a gluconeogenic stimu- 

 lus by the administration of adrenal cortical extract is not ol)served in the 

 scorbutic animal. Experiments such as these seem to establish a difference 

 in glycogen metabolism between scorbutic and normal animals, but more 

 work is needed to ascertain the specificity of this action of ascorbic acid, 

 and still more to work out the biochemical systems involved. 



7. Ascorbic Acid and the Synthesis of the Leuconostoc 

 citrovorum Factor 



The observation that a factor was necessaiy for the growth of the bac- 

 terial strain Leuconostoc citrovorum}'^ and that the growth factor was related 

 to folic acid was followed by the further observation that liver slices from 

 folic acid-deficient rats incubated with ascorbic acid alone approximately 

 doubled the content of the citrovorum factor in the tissue. Still larger in- 

 creases of the growth stimulant were observed if both folic acid and ascorbic 

 acid were added to the liver slices. The conclusion from the results of these 

 experiments was that folic acid is enzymatically converted into the citro- 

 vorum factor and that this conversion is aided by the presence of ascorbic 

 acid. '75 ■ '7« 



The finding that ascorbic acid enhances the conversion of folic acid to 

 citro\'orum factor is of great interest since, if the conversion is essential for 



"» A. Sigal and C. G. King, ./. Biol. Chem. 116, 489 (1936); J. Pharmacol. Exptl. 



Thcrap. 59, 468 (1937); 61, 1 (1937). 

 "2 S. Banerjee, Ann. Biuchem. and Exptl. Med. (India) 3, 157 (1943); 4, 33 (1944). 

 '"J. W. Patterson, Endue rinolugn 45, 344 (1949). 



»'< R. W. McKee, T. S. Cobhey, and Q. M. Geiman, Endocnnologi/ 45, 21 (1949). 

 "5 II. E. Sauberlich and C. A. Baumann, /. Biol. Chem. 176, 165 (1948); 181, 871 



(1949). 

 »'« E. E. Snell, E. Kitay, and W. S. McXutt, J. Biol. Chem. 173, 473 (1948). 



