Tryptophan is an essential amino acid that is required for normal development in Chlamydia species, and tryptophan metabolism has been implicated in chlamydial persistence and tissue tropism. The ability to synthesize tryptophan is not universal among the Chlamydiaceae, but species that have a predicted tryptophan biosynthetic pathway also encode an ortholog of TrpR, a regulator of tryptophan m...

Using substrate induction as a tool, we attempted to determine the role of tryptophan pyrrolase in the response to endotoxin in mice. Previous results have shown that the administration of the ld(50) of endotoxin lowers tryptophan pyrrolase activity. alpha-Methyltryptophan was found to maintain tryptophan pyrrolase activity above control levels in endotoxin-poisoned mice without increasing surv...

The essential amino acid tryptophan is a constituent of proteins and is also a substrate for two important biosynthetic pathways: the generation of neurotransmitter 5-hydroxytryptamine (serotonin) by tryptophan 5-hydroxylase, and the formation of kynurenine derivatives and nicotinamide adenine dinucleotides. The latter pathway is initiated by the enzymes tryptophan pyrrolase (tryptophan 2,3-dio...

The possible functional significance of induction of the hepatic enzymes, tryptophan pyrrolase and tyrosine transaminase, has been studied in intact normal and adrenalectomized adult male rats and in the isolated perfused rat liver. In intact, normal rats, several-fold increases in tryptophan pyrrolase activity induced by treatment with hydrocortisone or tryptophan, or both, were associated wit...

Application of a novel in vitro experimental system has allowed us to describe the relationship between tryptophan availability and serotonin release from rat hypothalamic slices. Superfusing hypothalamic slices with a physiologic medium containing l-tryptophan (1, 2, 5, or 10 microM) caused dose-dependent elevations in tissue tryptophan levels; the magnitude of the elevations produced by suppl...

The rate of tryptophan transport in Neurospora is regulated by the intracellular pool of tryptophan. When cells were shifted from growth in minimal medium to tryptophan-containing medium for 10 min, there was a 50% reduction in the rate of tryptophan transport. Intracellular tryptophan pools derived from indole were equally effective in reducing the rate of transport as externally supplied tryp...

A major factor regulating the synthesis of the neurotransmitter 5-hydroxytryptamine in the brain is the availability of the precursor amino acid, tryptophan. The K, of tryptophan hydroxylase (L-tryptophan mono-oxygenase, EC 1.14.16.4) is of the same order of magnitude as the brain concentration of tryptophan (Gal, 1974). Uptake of tryptophan into the brain is believed to be regulated by that fr...

BACKGROUND Intact protein rich in tryptophan was not seen as an alternative to pharmaceutical grade tryptophan since protein also contains large neutral amino acids (LNAAs) that compete for transport sites across the blood-brain barrier (BBB). Deoiled gourd seed (an extremely rich source of tryptophan-22 mg tryptophan/1 g protein) was combined with glucose, a carbohydrate that reduces serum lev...

The possible functional significance of induction of the hepatic enzymes, tryptophan pyrrolase and tyrosine transaminase, has been studied in intact normal and adrenalectomized adult male rats and in the isolated perfused rat liver. In intact, normal rats, several-fold increases in tryptophan pyrrolase activity induced by treatment with hydrocortisone or tryptophan, or both, were associated wit...

1. The percentage of human plasma tryptophan in the free state (ultrafilterable) was positively and significantly correlated with plasma non-esterified fatty acid (NEFA) concentration. 2. Results obtained either by adding tryptophan to plasma in vitro or from plasma taken during tryptophan infusion indicate one tryptophan binding site per albumin molecule and an inverse relationship between bin...