Hankes L V, Schmaeler M
Proc Soc Exp Biol Med. 1975 Sep;149(4):1063-8. doi: 10.3181/00379727-149-38959.
Labeled enantiomers of tryptophan, kynurenine, and hydroxykynurenine were given to five patients with scleroderma. Blood samples were drawn periodically over a 24-hr period. When the D-isomers were given, peak blood levels of radioactivity did not appear until 8 hr, whereas with the natural L-isomers peak levels were reached in 2 hr Considerable radioactivity was found firmly bound to the precipitated plasma proteins from both the L- and D-isomers. Incubation studies confirmed the binding of the D-isomers to the serum proteins. These experiments show that the use of pure labeled L-isomers is required, when studying the metabolism of amino acids in man, and that compounds other than L-tryptophan are bound to serum proteins in significant quantities.
将色氨酸、犬尿氨酸和羟基犬尿氨酸的标记对映体给予五名硬皮病患者。在24小时内定期采集血样。给予D-异构体时，放射性血药浓度峰值直到8小时才出现，而给予天然L-异构体时，2小时就达到了峰值。发现L-异构体和D-异构体的大量放射性都牢固地结合在沉淀的血浆蛋白上。孵育研究证实了D-异构体与血清蛋白的结合。这些实验表明，在研究人体氨基酸代谢时，需要使用纯的标记L-异构体，并且除L-色氨酸外的其他化合物也大量结合到血清蛋白上。
