Methylation of Homocystine by Chicks Deficient in Vitamin B12.

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Abstract
Chicks very deficient in vit.B12 grew as well when homocystine and betaine were added to a methionine-deficient diet as when a comparable amt. of methionine was added. No evidence was obtained that vit.B12 increased the efficiency with which preformed methyl groups were transferred to homocystine since the effects of vit.B12 were additive to those of methionine or its equivalents of homocystine plus labile methyl. It appears likely, however, that when the chick''s diet lacks methyl groups vit. B12 is concerned in the synthesis of such groups and their combination with homocystine to form methionine. Formation of methionine by this procedure, however, is limited and insufficient to meet the needs of the chick.