Neural tissue, methionine

The conclusion reached from these findings from the point of view of methionine metabolism in developing brain is that involvement of S-adenosylmethlonlne in methylation reactions is more important than its involvement in synthesis of polyamines. Furthermore, in its role as a methyl donor it is converted to S-adenosylhomocysteine by various methyltransferases, and the carbon skeleton is retained within the methionine-homocysteine cycle. The absence of an active transsulfuratlon pathway at these early stages of development supports the concept that the most important metabolic role of methionine in developing neural tissue is methylation. Thus metabolic pathways which involve loss of the methionine carbon skeleton, polyamine biosynthesis and transsulfuratlon, are minimal or absent in order to promote and conserve this remethylatlon cycle. These alterations in the pathways of methionine metabolism in developing tissue may also be necessary to compensate for the greater utilization of methionine for protein synthesis at this time. 

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