434 VITAMIN Bi2 



was vitamin B12, which is present in fish meal and has been shown to have 

 an effect on the response to methionine corresponding to that encountered 

 by Patton and coworkers. In other experiments (Table III) a similar effect 

 was noted for yeast extract, and in this case later evidence indicates that 

 folic acid may have been the factor involved, since yeast does not supply 

 effective amounts of vitamin B12. Thus vitamin B12 and folic acid both 

 have been shown to be needed for the biochemical reactions which are 

 concerned with the metabolism of the group of compounds, including 

 methionine, supplying "labile methyl" groups. Patton et al. concluded with 

 the following significant comment "... fish meal increases chick growth on 

 a corn-soybean diet by supplying some factor, known or unknown, whose 

 requirement has been augmented, or created, by the presence of corn and/or 

 soybean oil meal in the diet. This would explain the failure to discover any 



TABLE III 



Effect of Methionine and Yeast Extract on the Growth of Chicks When 



Added to a Basal Diet of Corn and Soybean Meal Supplemented with 



Vitamins and Choline" 



such factor using the purified diet. . . . The factor would be of great prac- 

 tical importance." 



A relation between vitamin Bi2 and methionine was described by Shive®^ 

 in January 1949. He reported that the crystalline vitamin could function 

 interchangeably with methionine in enabling the growth of Escherichia coli 

 to take place on a medium containing sulfanilamide. One part of vitamin 

 Bi2 was as active as 300,000 parts of methionine. Analogous findings were 

 reported by Davis and Mingioli,^^ who isolated mutants of E. coli which 

 were unable to grow in the absence of sulfanilamide unless vitamin B12 or 

 methionine was provided, under which conditions the mutants produced a 

 substance which appeared to be homocysteine. Homocysteine was ineffec- 

 tive, thus indicating a catalytic role for yitamin B12 in the transformation 

 of homocysteine to methionine. 



It was reported by Carrick and coworkers that either choline, methio- 

 nine,^^ or betaine,^"" when added to a basal diet consisting principally of 



88 B. D. Davis and E. S. Mingioli, J. Bacteriol. 60, 17 (1950). 



"9 R. W. Gerry, C. W. Carrick, and S. M. Hauge, Poultry Sci. 27, 161 (1948). 



