Biomaterial Database

Binding of nitric oxide to reduced L-tryptophan-2,3-dioxygenase as studied by electron paramagnetic resonance. 1976

Y Henry, and Y Ishimura, and J Peisach

Ferrous L-tryptophan-2,3-dioxygenase reacts with nitric oxide both in the presence and in the absence of L-tryptophan. Electron paramagnetic resonance studies suggest that the proximal ligand of the heme is a nitrogen atom, probably from an histidyl residue. The interaction of the protein with substrate changes both the symmetry of the paramagnetic center and the mode of interaction of the iron atom with its two axial ligands, NO and the proximal nitrogen atom. Optical absorption and EPR spectra suggest that the affinity of NO for tryptophan dioxygenase increases in the order: tryptophan dioxygenase, tryptophan dioxygenase + alpha-methyltryptophan, tryptophan diogenase " 5-hydroxytryptophan, tryptophan dioxygenase + L-tryptophan. A possible correlation between the number of superhyperfine lines in the EPR spectrum and the affinity of the enzyme for NO is discussed.

UI	MeSH Term	Description	Entries
D009569	Nitric Oxide	A free radical gas produced endogenously by a variety of mammalian cells, synthesized from ARGININE by NITRIC OXIDE SYNTHASE. Nitric oxide is one of the ENDOTHELIUM-DEPENDENT RELAXING FACTORS released by the vascular endothelium and mediates VASODILATION. It also inhibits platelet aggregation, induces disaggregation of aggregated platelets, and inhibits platelet adhesion to the vascular endothelium. Nitric oxide activates cytosolic GUANYLATE CYCLASE and thus elevates intracellular levels of CYCLIC GMP.	Endogenous Nitrate Vasodilator,Mononitrogen Monoxide,Nitric Oxide, Endothelium-Derived,Nitrogen Monoxide,Endothelium-Derived Nitric Oxide,Monoxide, Mononitrogen,Monoxide, Nitrogen,Nitrate Vasodilator, Endogenous,Nitric Oxide, Endothelium Derived,Oxide, Nitric,Vasodilator, Endogenous Nitrate
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D011551	Pseudomonas fluorescens	A species of nonpathogenic fluorescent bacteria found in feces, sewage, soil, and water, and which liquefy gelatin.	Bacillus fluorescens,Bacillus fluorescens liquefaciens,Bacterium fluorescens,Liquidomonas fluorescens
D004578	Electron Spin Resonance Spectroscopy	A technique applicable to the wide variety of substances which exhibit paramagnetism because of the magnetic moments of unpaired electrons. The spectra are useful for detection and identification, for determination of electron structure, for study of interactions between molecules, and for measurement of nuclear spins and moments. (From McGraw-Hill Encyclopedia of Science and Technology, 7th edition) Electron nuclear double resonance (ENDOR) spectroscopy is a variant of the technique which can give enhanced resolution. Electron spin resonance analysis can now be used in vivo, including imaging applications such as MAGNETIC RESONANCE IMAGING.	ENDOR,Electron Nuclear Double Resonance,Electron Paramagnetic Resonance,Paramagnetic Resonance,Electron Spin Resonance,Paramagnetic Resonance, Electron,Resonance, Electron Paramagnetic,Resonance, Electron Spin,Resonance, Paramagnetic
D001665	Binding Sites	The parts of a macromolecule that directly participate in its specific combination with another molecule.	Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining
D013053	Spectrophotometry	The art or process of comparing photometrically the relative intensities of the light in different parts of the spectrum.
D014364	Tryptophan	An essential amino acid that is necessary for normal growth in infants and for NITROGEN balance in adults. It is a precursor of INDOLE ALKALOIDS in plants. It is a precursor of SEROTONIN (hence its use as an antidepressant and sleep aid). It can be a precursor to NIACIN, albeit inefficiently, in mammals.	Ardeydorm,Ardeytropin,L-Tryptophan,L-Tryptophan-ratiopharm,Levotryptophan,Lyphan,Naturruhe,Optimax,PMS-Tryptophan,Trofan,Tryptacin,Tryptan,Tryptophan Metabolism Alterations,ratio-Tryptophan,L Tryptophan,L Tryptophan ratiopharm,PMS Tryptophan,ratio Tryptophan
D014366	Tryptophan Oxygenase	A dioxygenase with specificity for the oxidation of the indoleamine ring of TRYPTOPHAN. It is a LIVER-specific enzyme that is the first and rate limiting enzyme in the kynurenine pathway of TRYPTOPHAN catabolism.	Tryptophan Pyrrolase,TDO Dioxygenase,Tryptophan 2,3-Dioxygenase,2,3-Dioxygenase, Tryptophan,Dioxygenase, TDO,Oxygenase, Tryptophan,Pyrrolase, Tryptophan,Tryptophan 2,3 Dioxygenase