The uptake of 14C-labeled hydroxyanthranilic acid and enantiomers of tryptophan, kynurenine, and hydroxykynurenine in human blood. |
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Authors: | L V Hankes M Schmaeler |
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Abstract: | 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. |
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