Effects of ascorbic acid on hepatic nuclear binding of L-tryptophan

This study investigated the in vitro effects of ascorbic acid on nuclear L-tryptophan receptor binding of rat liver. Ascorbic acid at 10(-6)M to 10(-4)M inhibited the in vitro H-3-tryptophan binding to hepatic nuclei and nuclear envelope receptors. Addition of dithiothreitol, a protective agent for sulfhydryl groups, did not affect the inhibitory binding. Addition of L-leucine did reduce the inhibitory binding. Addition of NaCl (0.125 x 10(-4) M) did not influence the inhibitory binding effect of ascorbic acid but decreased the inhibitory effect of the NaCl on nuclear tryptophan binding. In vivo administration of ascorbic acid before or along with L-tryptophan decreased the L-tryptophan-induced stimulation of hepatic protein synthesis. (C) 2000 Elsevier Science Inc.