L-(甲基-~3H)-蛋氨酸的研制

L-(甲基-~3H)-蛋氨酸是重要的标记氨基酸之一,用于生命的起源、氨基酸在体内的合成与代谢等学科研究中,不少文章报道了用它来研究烷基取代的生化过程。 特定在甲基上标记的蛋氨酸一般都采用标记的碘甲烷与相应的去甲基化合物——高半胱氨酸在液氨溶液中反应而得。氚标记的碘甲烷是制备氚标记化合物的关键化合物,关于它的制备方法,文献上已有较多的报道,但我们根据实验室现有的条件,设计了一条合成

THE PREPARATION OF L-(METHYL-3H)-METHIONINE

A procedure for preparing L-(methyl-3H)-methionine is described. The method involves the tritiated sodium borohydride reduction of formaldehyde. This will be followed by io-dation to give a 80% yield of tritiated methyl iodide. Direct alkylation of the L-homo-cysteine anion, generated by the sodium-liquid ammonia reduction of L-methionine, by methyl-T iodide gives L-(methyl-3H)-methionine with 27% yield after purification. The specific activity of labelled methionine is 12.5 Ci/mM. The radiochemical purity is over 95%.Mass spectrum and NMR spectroscopy of deuterated methionine, prepared from deu-terated methyl iodide by the same method, show that the deuterium content of the S-methyl group is the same as that of the methyl iodide, and methionine specifically labelled in the methyl group is obtained.