Studies on the synthesis of stable-isotope-labeled amino acids canying functional group and their conformational analysis

近年来，稳定同位素标记与先进的多维核磁共振波谱相结合已成为测定溶液中蛋白质整体结构和局部结构的较有前途的方法。特别是，区域和立体选择性同位素标记的氨基酸是收集精确结构信息的极好探针，如特定残基的侧链构象。我们最近探索了仅对氨基酸侧链的一个非对映甲基和亚甲基质子进行立体选择性氘化的方法。然而，对侧链上携带官能团的氨基酸的研究，如赖氨酸、精氨酸、丝氨酸、半胱氨酸、天冬氨酸等，尽管它们在蛋白质功能中很重要，但仍未触及。在目前的工作中，我们研究了这类氨基酸的区域和立体选择性氘标记。代表性结果如下：1。研究了(2S,3S,4R,5R)-[2,3,4,5- d_4]的不对称合成。手性氘化3-氨基丙醇是由l -谷氨酸衍生的不饱和γ-内酯经几个官能团间转换催化氘化制备的。得到的氘标记的3-氨基丙烷与手性甘氨酸模板缩合得到不饱和鸟氨酸。然后对脱氢鸟氨酸进行催化氘化，然后进行脱保护，得到L-[2,3,4,5- d_4]鸟氨酸。以L-焦谷氨酸为原料合成L-[5,5,6,6- d_4]赖氨酸。用l -焦谷氨酸制备的氘化5-碘多诺缬氨酸进行了侧链的一次碳同源化。用L-[5,5,6,6- d_4]赖氨酸对得到的氰化物进行催化氘化，然后进行标准的脱保护程序。合成一种新的3,4-二去氢焦谷氨酸衍生物，其中羧基作为ABO酯被保护。所得的不饱和焦谷氨酸模板的一些反应，如二羟基化反应、迈克尔加成反应和一些环加成反应，以立体定向的方式发生。烯烃经催化氘化后进行酸水解得到(2S,3S,4R)-[3,4- d_2]谷氨酸。少

Recently, the combination of stable isotope labeling and advanced multidimensional NMR spectroscopy has become more promising method for determining the overall and local structures of proteins in solution. In particular, the regio-and stereoselectively isotope-labeled amino acids are excellent probes for collecting precise structural information such as the side-chain conformations about specific residues. We have recently explored the methods for stereoselective deuteration of only one of the diastereotopic methyl groups and methylene protons of amino acid side-chains. However, investigation of amino acids carrying a functional group in the side chain, such as lysine, arginine, serine, cystein, aspartic acid, and so on, remains untouched despite their importance in protein function. In the present work, we investigated the regio-and stereoselective deuterium labeling of such amino acids. The representative results are as follows.1. Asymmetric synthesis of (2S,3S,4R,5R)-[2,3,4,5-D_4]o … More rnithine was examined. The chirally deuterated 3-aminopropanal was prepared by a catalytic deuteration of an unsaturated -γ-lactone derived from L-glutamic acid followed by several functional group interconversions. Condensation of the obtained deuterium-labeled 3-aminopropanal with a chiral glycine template afforded unsaturated ornithine. The dehydroornithine was then subjected to a catalytic deuteration followed by deprotection to give the L-[2,3,4,5-D_4]ornithine.2. Synthesis of L-[5,5,6,6-D_4]lysine starting from L-pyroglutamic acid was investigated. One carbon homologation of the side chain was carried out by cyanation of deuterated 5-iodonorvaline prepared from L-pyroglutamic acid. Catalytic deuteration of the obtained cyanide followed by the standard deprotection procedure afforded L-[5,5,6,6-D_4]lysine.3. Synthesis of a novel 3,4-didehydropyroglutamate derivative in which the carboxylic group is protected as an ABO ester was examined. Some reactions of the obtained unsaturated pyroglutamate template such as dihydroxylation, Michael addition, and some cycloadditions were found to take place in a stereospecific manner. Catalytic deuteration of the olefin followed by acidic hydrolysis gave (2S,3S,4R)-[3,4-D_2]glutamic acid. Less