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Creation of thermostable l-tryptophan dehydrogenase by protein engineering and its application for l-tryptophan quantification.
Matsui, D, Asano, Y
Analytical biochemistry. 2019;:57-63
Abstract
l-Tryptophan dehydrogenase is a new NAD+-dependent amino acid dehydrogenase discovered in Nostoc punctiforme. The enzyme is involved in scytonemin biosynthesis and is highly selective toward l-tryptophan. By a growth-dependent molecular evolution technique, a thermostable mutant enzyme was selected successfully. l-Tryptophan concentration in human plasma was successfully determined using the thermostable mutant of l-tryptophan dehydrogenase.
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2.
Metabolic engineering for improving L-tryptophan production in Escherichia coli.
Niu, H, Li, R, Liang, Q, Qi, Q, Li, Q, Gu, P
Journal of industrial microbiology & biotechnology. 2019;(1):55-65
Abstract
L-Tryptophan is an important aromatic amino acid that is used widely in the food, chemical, and pharmaceutical industries. Compared with the traditional synthetic methods, production of L-tryptophan by microbes is environmentally friendly and has low production costs, and feed stocks are renewable. With the development of metabolic engineering, highly efficient production of L-tryptophan in Escherichia coli has been achieved by eliminating negative regulation factors, improving the intracellular level of precursors, engineering of transport systems and overexpression of rate-limiting enzymes. However, challenges remain for L-tryptophan biosynthesis to be cost-competitive. In this review, successful and applicable strategies derived from metabolic engineering for increasing L-tryptophan accumulation in E. coli are summarized. In addition, perspectives for further efficient production of L-tryptophan are discussed.
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3.
How important is tryptophan in human health?
Kałużna-Czaplińska, J, Gątarek, P, Chirumbolo, S, Chartrand, MS, Bjørklund, G
Critical reviews in food science and nutrition. 2019;(1):72-88
Abstract
Tryptophan (Trp) is an amino acid and an essential component of the human diet. It plays a crucial role in many metabolic functions. Clinicians can use Trp levels in the course of diagnosing various metabolic disorders and the symptoms associated with those diseases. Furthermore, supplementation with this amino acid is considered in the treatment of depression and sleep disorders, mainly due to the Trp relationship with the synthesis of serotonin (5-HT) and melatonin. It is also used in helping to resolve cognitive disorders, anxiety, or neurodegenerative diseases. Reduced secretion of serotonin is associated with autism spectrum disorder, obesity, anorexia and bulimia nervosa, and other diseases presenting peripherals symptoms. The literature strongly suggests that Trp has a significant role in the correct functionality of the brain-gut axis and immunology. This information leads to the consideration of Trp as an essential dietary component due to its role in the serotonin pathway. A reduced availability of Trp in diet and nutraceutical supplementation should be considered with greater concern than one might expect. This paper constitutes a review of the more salient aspects gleaned from the current knowledge base about the role of Trp in diseases, associated nutritional disorders, and food science, in general.
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4.
The molecular aspects of oxidative & nitrosative stress and the tryptophan catabolites pathway (TRYCATs) as potential causes of depression.
Wigner, P, Czarny, P, Galecki, P, Su, KP, Sliwinski, T
Psychiatry research. 2018;:566-574
Abstract
Depression is the most common mental disorder in the world. It is estimated that 350 million people suffer from depression worldwide. Depressive disorders will have become the second most frequent health problem globally by the year 2020, just behind ischemic heart disease. The causes of depressive disorders are not fully known. Previous studies showed that impaired tryptophan catabolites pathway, oxidative and nitrosative stress may play an important role in the pathogenesis of depression. Patients with depression have lower plasma levels of superoxide dismutase and glutathione peroxidise in comparison to controls. Moreover, depressed patients are characterized by decreased plasma levels of zinc, coenzyme Q10, albumin, uric acid, vitamin E and glutathione. Abnormal nitric oxidative production and nitric oxide synthase activity are also associated with depression. A dysfunction of the tryptophan catabolites pathway, indicated by increased levels of tryptophan 2,3-dioxygenase and indoleamine 2,3-dioxygenase, is also involved in the development of depression. Furthermore, increased levels of kynurenine and quinolinic acid might cause depression. Moreover, studies to date indicate that 8-oxyguanine, malondialdehyde, and 8-iso-prostaglandin F2α may serve as possible biomarkers. Additionally, regulation of defective mechanisms may provide a promising direction for the development of new and effective therapies.
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5.
Tryptophan metabolites kynurenine and serotonin regulate fibroblast activation and fibrosis.
Dolivo, DM, Larson, SA, Dominko, T
Cellular and molecular life sciences : CMLS. 2018;(20):3663-3681
Abstract
Fibrosis is a pathological form of aberrant tissue repair, the complications of which account for nearly half of all deaths in the industrialized world. All tissues are susceptible to fibrosis under particular pathological sets of conditions. Though each type of fibrosis has characteristics and hallmarks specific to that particular condition, there appear to be common factors underlying fibrotic diseases. One of these ubiquitous factors is the paradigm of the activated myofibroblast in the promotion of fibrotic phenotypes. Recent research has implicated metabolic byproducts of the amino acid tryptophan, namely serotonin and kynurenines, in the pathology or potential pharmacologic therapy of fibrosis, in part through their effects on development of myofibroblast phenotypes. Here, we review literature underlying what is known mechanistically about the effects of these compounds and their respective pathways on fibrosis. Pharmacologic administration of kynurenine improves scarring outcomes in vivo likely not only through its well-characterized immunosuppressive properties but also via its demonstrated antagonism of fibroblast activation and of collagen deposition. In contrast, serotonin directly promotes activation of fibroblasts via activation of canonical TGF-β signaling, and overstimulation with serotonin leads to fibrotic outcomes in vivo. Recently discovered feedback inhibition between serotonin and kynurenine pathways also reveals more information about the cellular physiology of tryptophan metabolism and may also underlie possible paradigms for anti-fibrotic therapy. Together, understanding of the effects of tryptophan metabolism on modulation of fibrosis may lead to the development of new therapeutic avenues for treatment through exploitation of these effects.
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6.
Beneficial actions of microbiota-derived tryptophan metabolites.
Galligan, JJ
Neurogastroenterology and motility. 2018;(2)
Abstract
Tryptophan is an important dietary amino acid and it is the precursor for 5-hydroxytryptamine synthesis in the nervous system and by enterochromaffin cells in the gut mucosa. Tryptophan is also metabolized by enzymes in the gut mucosa and also by enzymes produced by the gut microbiome. Diet and the microbiome can contribute to metabolic disease in part by causing intestinal inflammation and increased permeability. In this issue of Neurogastroenterology and Motility, Jennis et al. test the hypothesis that indole tryptophan metabolites produced by gut bacteria might be responsible for the anti-inflammatory and beneficial metabolic effects of the gut microbiome and Roux-en-Y gastric bypass surgery for weight loss by obese patients. The authors identified indole-3-propionic acid as the beneficial metabolite. A review of the literature also revealed the beneficial effects of tryptophan metabolites on diabetes and metabolic disease and on inflammatory bowel disease. Taken together, these data highlight another health benefit of the intestinal microbiome, which produces beneficial products from dietary amino acids especially tryptophan.
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7.
Perspectives of ruthenium(ii) polyazaaromatic photo-oxidizing complexes photoreactive towards tryptophan-containing peptides and derivatives.
Estalayo-Adrián, S, Garnir, K, Moucheron, C
Chemical communications (Cambridge, England). 2018;(4):322-337
Abstract
RuII polyazaaromatic complexes have been studied with the aim of developing molecular tools for DNA and oligonucleotides. In this context, RuII-TAP (TAP = 1,4,5,8-tetraazaphenanthrene) complexes have been developed as specific photoreagents targeting the genetic material. The advantage of such compounds is due to the formation of photo-addition products between the Ru-TAP complex and the biomolecule, originating from a photo-induced electron transfer process that takes place between the excited Ru-TAP complex and guanine (G) bases of DNA. This photo-addition has been more recently extended to amino acids in view of applications involving peptides, such as inhibition or photocontrol of proteins. More particularly, tryptophan (Trp) and Trp-containing peptides are also able to be photo-oxidized by RuII-TAP complexes, leading to the formation of photo-addition products. This mini review focuses on recent advances in the search for RuII polyazaaromatic photo-oxidizing complexes of interest as molecular tools and photoreagents for Trp-containing peptides and proteins. Different possible future directions in this field are also discussed.
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8.
[The importance of the kynurenine pathway in depressive disorders].
Jasionowska, J, Filip, M, Talarowska, M, Gałecki, P
Polski merkuriusz lekarski : organ Polskiego Towarzystwa Lekarskiego. 2018;(266):89-93
Abstract
Depressive disorders are the most frequently diagnosed mental disorder. It is assumed that the etiology of depression is multifactorial and the individual theories complement each other. Referring to the neurochemical hypothesis of the underlying depressive disorder, the relationship between lowering levels of serotonin, norepinephrine, dopamine and a change in mood is suggested. Particular attention has been given to serotonin, called the happiness hormone, which is synthesized from the exogenous amino acid tryptophan. The main methods of antidepressant treatment, in particular the use of serotonin reuptake inhibitors (SSRIs), take into account the concept of monoamine deficiency in patients with depression. However, an insufficient response in some patients to antidepressants (the existence of a refractory depression), indicates the importance of looking for other possible causes for the development of this disease and thus alternative treatment methods. It is indicated that in patients with depression there are disorders of tryptophan metabolism, ie the redirection of tryptophan from the serotonin synthesis pathway to the kynurenine pathway, which is the source of neuroactive compounds in the central nervous system, so-called. kynurenin m.in. kynurenic acid, 3-hydroxycinurenine, quinoline acid. It has been proved that certain metabolites of this cycle of transformations have neuroprotective and other neurotoxic properties. For this reason, it seems reasonable to summarize the research published so far on this subject.
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9.
Acute and chronic effects of exercise on the kynurenine pathway in humans - A brief review and future perspectives.
Metcalfe, AJ, Koliamitra, C, Javelle, F, Bloch, W, Zimmer, P
Physiology & behavior. 2018;:583-587
Abstract
Tryptophan (TRP) is an essential amino acid. Metabolites of TRP have been identified as important mediators in immune regulation and function of the central nervous system. Inflammation strongly stimulates to the breakdown of TRP into Kynurenine (KYN), representing the initial step of the KYN pathway. Recently, exercise interventions have been able to demonstrate a modification of the KYN pathway plausibly by altering inflammation. However, modifications differ between acute and chronic exercise interventions. As such, this review examines the current studies that have investigated the effect of an acute (single bout) or chronic (training) exercise intervention on levels of TRP and KYN in both healthy and diseased populations.
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10.
Novel chemical degradation pathways of proteins mediated by tryptophan oxidation: tryptophan side chain fragmentation.
Schöneich, C
The Journal of pharmacy and pharmacology. 2018;(5):655-665
Abstract
OBJECTIVES This minireview focuses on novel degradation pathways of proteins in solution via intermediary tryptophan (Trp) radical cations, which are generated via photo-induced electron transfer to suitable acceptors such as disulfide bonds. METHODS Gas-phase mass spectrometry studies had indicated the potential for Trp radical cations to fragment via release of 3-methylene-3H-indol-1-ium from the side chain. HPLC-MS/MS analysis demonstrates that analogous fragmentation reactions occur during the exposure of peptides and proteins to light or accelerated stability testing. KEY FINDINGS The light exposure of selected peptides and monoclonal antibodies leads to the conversion of Trp to glycine (Gly) or glycine hydroperoxide (GlyOOH), where GlyOOH could be reduced to hydroxyglycine, which undergoes subsequent cleavage. Product formation is consistent with Cα -Cβ fragmentation of intermediary Trp radical cations. For the peptide octreotide and specific glycoforms of IgG1 Fc domains, Trp side chain cleavage in aqueous solution is indicated by the formation of 3-methyleneindolenine (3-MEI), which adds to nucleophilic side chains, for example to Lys residues adjacent to the original Trp residues. CONCLUSIONS Trp side chain cleavage leads to novel reaction products on specific peptide and protein sequences, which may have consequences for potency and immunogenicity.