Kynureninase activity in fetal tissue of rat is two thirds the level of the adult, while kynurenine aminotransferase (L-kynurenine: 2-oxoglutarate aminotransferase, EC. 2. 6. 1. 7) activity could not be observed at all in fetal tissue. The latter began to arise after birth and reached the adult level at 50 g of body weight. This fact suggests that anthranilic acid in fetal tissue might have som...

This review presents an up-to-date assessment of the role of the tryptophan metabolic and catabolic pathways in neurodegenerative disease and HIV-associated neurocognitive disorder. The kynurenine pathway and the effects of each of its enzymes and products are reviewed. The differential expression of the kynurenine pathway in cells within the brain, including inflammatory cells, is explored giv...

The kynurenine pathway (KP) metabolizes the essential amino acid tryptophan and generates a number of neuroactive metabolites collectively called the kynurenines. Segregated into at least two distinct branches, often termed the "neurotoxic" and "neuroprotective" arms of the KP, they are regulated by the two enzymes kynurenine 3-monooxygenase and kynurenine aminotransferase, respectively. Intere...

Tumor immune escape mechanisms are being regarded as suitable targets for tumor therapy. Among these, tryptophan catabolism plays a central role in creating an immunosuppressive environment, leading to tolerance to potentially immunogenic tumor antigens. Tryptophan catabolism is initiated by either indoleamine 2,3-dioxygenase (IDO-1/-2) or tryptophan 2,3-dioxygenase 2 (TDO2), resulting in biost...

Mammalian cells rely on cellular uptake of the essential amino acid tryptophan. Tryptophan sequestration by up-regulation of the key enzyme for tryptophan degradation, indoleamine 2,3-dioxygenase (IDO), e.g., in cancer and inflammation, is thought to suppress the immune response via T cell starvation. Additionally, the excreted tryptophan catabolites (kynurenines) induce apoptosis of lymphocyte...

BACKGROUND Brain-derived neurotrophic factor (BDNF) deficiency confers vulnerability to stress, but the mechanisms are unclear. BDNF(+/-) mice exhibit behavioral, physiological, and neurochemical changes following low-level stress that are hallmarks of major depression. After immune challenge, neuroinflammation-induced changes in tryptophan metabolism along the kynurenine pathway mediate depres...

Neuropsychiatric symptoms of systemic lupus erythematosus (NP-SLE) have been understudied compared to end-organ failure and peripheral pathology. Neuropsychiatric symptoms, particularly affective and cognitive indications, may be among the earliest manifestations of SLE. Among the potential pathophysiological mechanisms responsible for NP-SLE are increased peripheral pro-inflammatory cytokines,...

The major degradative pathway in mammals for the essential amino acid tryptophan is initiated by oxidative cleavage of the pyrrole ring. The first readily detectable metabolite on this pathway is kynurenine. Its formation is measured in the assay in uitro of the liver enzyme catalysing this reaction, tryptophan pyrrolase (tryptophan 2,3-dioxygenase, EC 1.13.11.11), normally by monitoring A365 (...

linear regression coefficients (r) were 0.981 for tryptophan (slope 1.004) and 0.905 for kynurenine (slope 1.21). The presented method is well suited for high throughput of samples. Approximately 150 specimens can be measured with one chromatographic system per day. On the one hand, it allows measurement of tryptophan and kynurenine concentrations with high sensitivity. Determination of tryptop...

1. Kynurenine-2-oxoglutarate aminotransferase (isoenzyme 1) was purified to homogeneity from the liver, brain and small intestine of rats by the same procedure. The three enzyme preparations had nearly identical pH optima, substrate specificities and molecular weights. Isoenzyme 1 was active with 2-oxoglutarate but not with pyruvate as amino acceptor, and utilized a wide range of amino acids as...