Role of S-Adenosylmethionine in Vitamin B12-dependent Methionine Synthesis

Role of S-adenosylmethionine in vitamin B12-dependent methionine synthesis.

Role of S-adenosylmethionine in methionine biosynthesis in yeast.

Extracts of Saccharomyces cerevisiae were used to develop a cell-free system capable of converting the beta-carbon of serine into the methyl group of methionine. No requirement for either S-adenosylmethionine or S-adenosylhomocysteine could be demonstrated for net methionine biosynthesis. Growth of the cells in B(12) did not affect the reaction. The mechanism for the methylation of homocysteine...

The effect of methionine and S-adenosylmethionine on S-adenosylmethionine levels in the rat brain.

OBJECTIVE S-Adenosylmethionine (SAMe) is a major methyl donor in the brain and is also an antidepressant with few reported side effects; however, SAMe is relatively expensive and unstable. Brain SAMe can be increased by giving methionine to rats, raising the possibility that methionine may be an antidepressant. We aimed to study whether SAMe and methionine, when given orally to rats, could rais...

Further studies on the relationship of vitamin B12 to methionine synthesis in extracts of Escherichia coli.

It has been reported (2) that extracts of Escherichia coli PA15 (a mutant requiring serine or glycine for growth) prepared from cells grown on a medium containing vitamin B12, contain a factor which is required for methionine synthesis from homocysteine. The need for this factor is apparent only when tetrahydrofolate is employed as a carrier of precursors of the methyl group. Either carbon 3 of...

L-methionine availability regulates expression of the methionine adenosyltransferase 2A gene in human hepatocarcinoma cells: role of S-adenosylmethionine.

In mammals, methionine adenosyltransferase (MAT), the enzyme responsible for S-adenosylmethionine (AdoMet) synthesis, is encoded by two genes, MAT1A and MAT2A. In liver, MAT1A expression is associated with high AdoMet levels and a differentiated phenotype, whereas MAT2A expression is associated with lower AdoMet levels and a dedifferentiated phenotype. In the current study, we examined regulati...