CHOLINE 



made good by giving choline, for a certain minimum amount of 

 methionine is needed by both the rat ^^ and the chick ^^ for purposes 

 unconnected with methylation. Similarly, when a severe choline 

 deficiency was induced in chicks ^^» ^* or turkeys, ^^ methionine could 

 not replace choline in preventing the characteristic perosis. This 

 suggests that the anti-perotic action of choline is distinct from its 

 growth- promoting and lipotropic actions. 



A combined severe choline and partial methionine deficiency was 

 induced in chicks by H. J. Almquist and C. R. Grau.^^ The addition 

 of methionine to the diet increased the gain in weight to about two- 

 thirds of the normal value. Better, but still limited, growth was 

 obtained with a partial deficiency of methionine and ample amounts 

 of choline. That choline and methionine were only partially bio- 

 logically equivalent was confirmed by D. S. McKittrick,^^ who found 

 that, for optimal growth, white Leghorn chicks required 0-5 % of 

 methionine and o-i % of choline chloride, together with an additional 

 0-25 % of methionine or an additional 0-45 % of choline chloride, or 

 an equivalent mixture of the two. Excess methionine depressed the 

 growth and this could be counteracted by adding a methyl acceptor, 

 such as glycocyamine, or serine. 



In rat liver, choline is partly responsible for the conversion of 

 glycine into serine. ^^^ 



Betaine and Sarcosine 



Methionine is not the only substance that can serve as a substitute 

 for choline for, under certain conditions, betaine 



(CH,)8N . CH2 . coo- 

 is capable of exerting a growth effect in the chick equivalent to that 

 of choline,^^ especially in presence of ethanolamine.^^ Like methio- 

 nine, however, it did not cure perosis in chicks, ^^» ^^' ^^ nor could it 

 completely replace choline or methionine, but only that portion of 

 the one that could be replaced by the other. ^' 



Betaine containing deuterio-methyl groups and N^^ was shown to 

 be an effective methyl donator,^^ and the methyl groups appeared in 

 the tissue choline as quickly as they did from dietary deuterio-choline. 

 There was a discrepancy, however, between the amount of N^^ and 

 deuterium in the choline, indicating that betaine was not converted 

 as a whole into choline. Dimethylglycine containing deuterium gave 

 rise to choline and creatine only to a very limited extent. Sarcosine 

 containing W^ and deuterium was also an effective methylating agent, 

 but creatine was formed much more slowly from sarcosine than from 

 choline. 22 



600 



