Consideration of betaine and one-carbon sources of N5-methyltetrahydrofolate for use in homocystinuria and neural tube defects
Consideration of betaine and one-carbon sources of N5-methyltetrahydrofolate for use in homocystinuria and neural tube defects
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DOI：
10.1093/ajcn/85.4.946
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发表时间：
2007-04-01
影响因子：
7.1
通讯作者：
Benevenga, Norlin J.
中科院分区：
文献类型：
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作者：
Benevenga, Norlin J.
试图改善同型半胱氨酸尿症和神经管缺陷的一个主要焦点是在饮食中补充维生素B。这些病例的代谢缺陷可能部分是由于缺乏甲基。补充维生素B支持对酶辅助因子的需求，但不能以甲基的形式提供底物。L-蛋氨酸是蛋白质合成所必需的一种必需氨基酸，但作为代谢的主要甲基供体S-腺苷蛋氨酸，在代谢中也发挥着独特的作用。观察到在L蛋氨酸代谢中产生的L同型半胱氨酸在被破坏之前被重新甲基化2-4次，这是理解甲基团缺乏的可能性的关键。这表明，支持蛋白质合成所需的甲基基团(即S-腺苷蛋氨酸)可能是蛋氨酸的2-4倍。甜菜碱或N-5-甲基四氢叶酸可使L-同型半胱氨酸重新甲基化生成L-蛋氨酸。在治疗同型半胱氨酸尿症和神经管畸形时，应考虑甜菜碱和一碳来源导致N-5-甲基四氢叶酸的产生和L-同型半胱氨酸的再甲基化形成L-蛋氨酸。
A major focus in attempts to ameliorate homocystinuria and neural tube defects is supplementation of the diet with B vitamins. The metabolic defect in these cases may be due in part to a deficiency of methyl groups. B vitamin supplementation supports the need for enzyme cofactors but cannot provide substrate in the form of methyl groups. L-Methionine is an essential amino acid and is required for protein synthesis, but it also plays a unique role in metabolism as S-adenosylmethionine, which is the primary methyl donor in metabolism. The observation that L-homocysteine, which is produced in the metabolism Of L-methionine, is remethylated 2-4 times before it is destroyed is key to understanding the possibility of a methyl group deficiency. This suggests that the requirement for methyl groups (ie, S-adenosylmethionine) may be 2-4 times that for methionine in support of protein synthesis. L-Homocysteine can be remethylated to form L-methionine by betaine or N-5-methyltetrahydrofolate. Betaine and one-carbon sources that lead to the production of N-5-methyltetrahydrofolate and the remethylation Of L-homocysteine to form L-methionine should be considered along with B vitamin supplementation in the treatment of homocystinuria and neural tube defects.