The five enzyme activities in the synthesis of l-tryptophan have been obtained in extracts of Euglena gracilis. One of these, tryptophan synthetase, has been studied in detail. The general catalytic properties of tryptophan synthetase, including the range of reactions catalyzed and its substrate and cofactor affinities, are similar to those reported for other organisms. The Euglena enzyme has t...

OBJECTIVE The S'/S' (S/S, S/Lg and Lg/Lg) variant of the serotonin (5-HT) transporter gene linked polymorphic region (5-HTTLPR) is associated with less efficient neurotransmission and may be more reactive to 5-HT manipulations. We tested the effects of l-tryptophan supplements on the cortisol response induced by a social stressor in S'/S' and L'/L' (La/La) carriers. METHODS In a double-blind ...

Depending on their protein content, single meals can rapidly influence the uptake of amino acids into the brain and thereby modify brain functions. The current study investigates the effects of two different amino acids on the human gut-brain system, using a multimodal approach, integrating physiological and neuroimaging data. In a randomized, placebo-controlled trial, L-tryptophan, L-leucine, ...

The effects of daily dietary Bacillus subtilis (Bs), and adding L-tryptophan, fructan, or casein to fecal fermentation broths were investigated as means to reduce the production of noxious gas during manure fermentation caused by ammonia, hydrogen sulfide (H2S), and 3-methylindole (skatole). Eighty swine (50.0±0.5 kg) were equally apportioned to an experimental group given Bs in daily feed, or ...

Some children with coeliac disease show behavioural disorders such as depression and other signs which have been correlated with reduced central monoamine metabolism. We have therefore investigated the brain availability of the monoamine precursors tryptophan and tyrosine in 15 untreated children with coeliac disease and 12 treated children with coeliac disease as well as in 12 control children...

The equilibrium constants for the tryptophan binding to indoleamine 2,3-dioxygenase, a protohemoprotein, in its ferric (Fe3+), ferrous (Fez+), and CO-bound (Fea+CO) forms were determined by the spectrophotometric titration method. All these enzyme derivatives showed marked spectral changes upon tryptophan binding. Such a spectral change for the ferric enzyme was, however, specific to the L isom...

The putative prenyltransferase gene ACLA_031240 belonging to the dimethylallyltryptophan synthase superfamily was identified in the genome sequence of Aspergillus clavatus and overexpressed in Escherichia coli. The soluble His-tagged protein EAW08391 was purified to near homogeneity and used for biochemical investigation with diverse aromatic substrates in the presence of different prenyl dipho...

The effects of L-tryptophan (4 g) on the waking EEG and daytime sleep were studied in a group of 20 normal adults. Subjects were assigned to a morning or afternoon group, and data were collected on two occasions, after L-tryptophan and after placebo, assigned in a counterbalanced order. L-Tryptophan significantly reduced sleep latency without altering nap sleep stages and elevated plasma total ...

1. An enzyme that catalyzes the formation of fOrmyl-Dkynurenine from D-tryptophan was purified about loo-fold from a homogenate of rabbit small intestine. Formyl-~kynurenine thus produced was converted to D-kynurenine by formamidase present in rabbit intestine. 2. Methylene blue and ascorbic acid were required as cofactors. Xanthine oxidase with hypoxanthine could replace ascorbic acid, but hyd...