Biochemical synthesis of stereospecifically hydrogen labeled compounds on a preparative scale, VI1-3 Synthesis of further substrates of NAD(P)-linked dehydrogenases of high specific tritium content.
The preparation of (R) and (S) [2(-3)H]lactate as well as (S) [2(-3)H] glutamate via the coupled exchange reaction catalyzed by NAD linked dehydrogenases and NADH: lipoamide oxidoreductase (diaphorase) is described. The specific radioactivity of the hydrogen ions of the 3HOH/H2O can be obtained in the substrates (100% exchange) if equilibrium isotope effects are disregarded. By the exchange procedure substrates with higher specific radioactivity are obtained from positionally [3H]labeled racemic mixtures prepared by chemical reductions with [3H]labeled hydrides. The tritium content of one of the enantiomeres is "washed out" into water. As examples are presented the preparation of (R) [2-3H] (S) [2-H]malate as well as the corresponding carnitine, glutamate and (R) and (S) lactate.
D000429:Alcohol Oxidoreductases / Q000378:metabolism; D002331:Carnitine / Q000096:biosynthesis; D008058:Dihydrolipoamide Dehydrogenase / Q000378:metabolism; D005971:Glutamates / Q000096:biosynthesis*; D007553:Isotope Labeling; D007773:Lactates / Q000096:biosynthesis*; D008293:Malates / Q000096:biosynthesis; D014316:Tritium
D005971:Glutamates; D007773:Lactates; D008293:Malates; D014316:Tritium; D000429:Alcohol Oxidoreductases; D008058:Dihydrolipoamide Dehydrogenase; D002331:Carnitine