I. Urinary excretion of tryptophan metabolites of the kynurenine pathway before and after a loading dose of 2 g of L-tryptophan (both before and during supplementation with vitamin B6) was studied in normal young male subjects and in elderly male subjects with prostatic diseases. 2. The increase in urinary excretion of tryptophan metabolites in the normal male subjects after a loading dose of 2...

Evaluating the formation of tryptophan glycoconjugates other than well-established Amadori rearrangement products, HPLC-tandem MS (MS/MS) analysis of human urine collected from several healthy individuals proved the presence of one distinct tryptophan C-glycosyl compound [Horiuchi, Yonekawa, Iwahara, Kanno, Kurihara and Fujise (1994) J. Biochem. (Tokyo) 115, 362-366]. After isolation, unambiguo...

Enzyme derepression and feedback inhibition of the first enzyme are the regulatory mechanisms demonstrated for the tryptophan pathway in Saccharomyces cerevisiae. The relative contributions of the two mechanisms to the control of the flux through the pathway in vivo were analyzed by (i) measuring feedback inhibition of anthranilate synthase in vivo, (ii) determining the effect of regulatory mut...

Chlamydia trachomatis is an obligate intracellular pathogen that requires specific essential nutrients from the host cell, one of which is the amino acid tryptophan. In this context interferon gamma (IFNγ) is the major host protective cytokine against chlamydial infections because it induces the expression of the host enzyme, indoleamine 2,3-dioxygenase 1, that degrades tryptophan, thereby rest...

Tryptophan catabolism in cancer is increasingly being recognized as an important microenvironmental factor that suppresses antitumor immune responses. It has been proposed that the essential amino acid tryptophan is catabolized in the tumor tissue by the rate-limiting enzyme indoleamine-2,3-dioxygenase (IDO) expressed in tumor cells or antigen-presenting cells. This metabolic pathway creates an...

Binding of bilirubin and of L-tryptophan to dansylated albumins was investigated. Dansylation of less than one lysine residue per molecule of albumin did not affect the bilirubin binding, but decreased the L-tryptophan binding, indicating that dansylation had taken place in or near the l-tryptophan-binding site. Native albumin and albumin-bilirubin 1:1 complex showed the same affinity for L-try...

1. The increase in the haem saturation of rat liver tryptophan pyrrolase caused by tryptophan administration was previously shown to be associated with a decrease in 5-aminolaevulinate synthase activity. 2. It is now shown that similar reciprocal effects are caused by palmitate and salicylate, both of which increase tryptophan availability to the liver by direct displacement of the serum-protei...

Reports from several laboratories have shown that cats display a peculiar tryptophan metabolism as compared with other mammals. In 1941, Kotake and Nakayama (1) reported that L-kynurenine could be quantitatively converted to anthranilic acid when incubated with cat liver preparations. Gordon, Kaufman, and Jackson (a), on the other hand, found no kynurenic acid in urine of cats even when tryptop...