Recent interest in tryptophan metabolism has been stimulated by evidence that tryptophan is a precursor of nicotinic acid in mammals (1) as well as in Neurospora CTUSSU (2). The formation of kynurenine, kynurenic acid, and xanthurenic acid from tryptophan has been demonstrated by numerous experiments (3-5) and has been confirmed by isotope technique in the case of kynurenine and kynurenic acid ...

Tryptophan fluorescence is extensively used for label-free protein characterization. Here, we show that by analyzing how the average tryptophan fluorescence intensity varies with excitation modulation, kinetics of tryptophan dark transient states can be determined in a simple, robust and reliable manner. Thereby, highly environment-, protein conformation- and interaction-sensitive information c...

L-Tryptophan administered to normal or adrenalectomized rats inhibits formation of g@cogen from pyruvate, aspartate, or malate and from endogenous sources under the influence of hydrocortisone, but not from glucose or glycerol. The site of inhibition was located by determining the concentration of hepatic metabolites in fasted, normal rats and in fasted, adrenalectomized rats treated with trypt...

We developed a two-photon autofluorescence lifetime imaging system with excitations selected from the supercontinuum generated from a photonic crystal fiber. The system excites multiple endogenous fluorophores, such as nicotinamide adenine dinucleotide (NADH) and tryptophan, simultaneously and produces coregistered two-photon autofluorescence images of a biological sample. The technology provid...

The Escherichia coli trpR gene encodes tryptophan aporepressor, which binds the corepressor ligand, L-tryptophan, to form an active repressor complex. The side chain of residue valine 58 of Trp aporepressor sits at the bottom of the corepressor (L-tryptophan) binding pocket. Mutant trpR genes encoding changes of Val58 to the other 19 naturally occurring amino acids were made. Each of the mutant...

Microcystins are cyclic peptides produced by cyanobacteria, which can be harmful to humans and animals when ingested. Eight of the (more than) 90 microcystin variants presently characterized, contain the amino acid tryptophan. The well-researched oxidation products of tryptophan; kynurenine, oxindolylalanine, and N-formylkynurenine, have been previously identified in intact polypeptides but mic...

The method to be described for the determination of tryptophan is based on the reaction between xanthydrol and tryptophan in acid solution to form a highly colored, acid-stable product (1). In the presence of excess xanthydrol the formation of xanthydryltryptophan is directly related to the quantity of tryptophan in the solution. Although other indole derivatives likewise react with xanthydrol ...

L-Tryptophan and some of its analogues were previously observed to bind predominately at one site on human serum albumin (1). The unique nature of this site which favors the binding of L-tryptophan with an association constant 100 times greater than n-tryptophan made it seem worthwhile to investigate the entropy, enthalpy, and free energy changes accompanying the association at this site. In ad...

Several cell lines resistant to 5-methyltryptophan were selected from wild type cells of different Catharanthus roseus suspension cultures. The resistant cells had up to 30 times the normal levels of free tryptophan. Despite the increased pool size of tryptophan anthranilate synthetase activity of resistant cells was as sensitive to inhibition by L-tryptophan as wild type cells. The overproduct...

Arthrobacter species, isolated from the leaf cavities and the microsporocarps of the aquatic fern species Azolla pinnata and Azolla filiculoides, produced indole-3-acetic acid (IAA) in culture when the precursor tryptophan was added to the medium. No IAA production was detected in the absence of tryptophan. Maximum IAA formation was obtained in the first 2 d of incubation. Part of the tryptopha...