The taxonomic range for the selected organisms is: Saccharomyces cerevisiae The expected taxonomic range for this enzyme is: Bacteria, Eukaryota, Archaea
the mechanism of L-Kyn catalysis by KMO is composed of reductive and oxidative half reactions. The binding of the substrate induces the reduction of FAD by NADH or by NADPH
the mechanism of L-Kyn catalysis by KMO is composed of reductive and oxidative half reactions. The binding of the substrate induces the reduction of FAD by NADH or by NADPH. The initiation of FAD reduction is not unique to the substrate binding. It is also observed upon the binding of several inhibitors. The molecules that induce reduction of FAD other than the substrate are named as non-substrate effectors, e.g. UPF-648 for enzyme scKMO. Since the non-substrate effectors eliminate the hydroxyl transfer event but nonetheless initiate the formation of the FAD-hydroperoxide intermediate, they cause hydrogen peroxide formation. The triggering factor can arise from the substrate induced conformational changes in the loop above the isoalloxazine ring system
the enzyme is a very potent suppressor of toxicity of a fragment of the protein huntingtin, Htt, which causes the neurodegenerative Huntington disease in humans by aggregation in nuclear and cytoplasmic inclusion bodies
the enzyme is a very potent suppressor of toxicity of a fragment of the protein huntingtin, Htt, which causes the neurodegenerative Huntington disease in humans by aggregation in nuclear and cytoplasmic inclusion bodies
KMO has an FAD cofactor, utilizes either NADPH or NADH, releases NADP+ /NAD+ after flavin reduction, and has one dinucleotide-binding domain. Rossmann fold simply characterizes a secondary structure with an alternating motif of beta sheets and alpha helices, and is of importance because this domain non-covalently binds the FAD cofactor and also contains the active site of the enzyme for KMO
UPF648, UPF648 prevents the binding of the native substrate KYN by binding closely to the FAD cofactor. Enzyme-binding structure determination (PDB ID 4J36) and further pharmacophore modeling
enzyme structure and ligand interaction analysis using the crystal structure of scKMO (PDB ID 4J34), library screening from Zinc15 database, detailed overview
KMO belongs to a family of NAD(P)H-dependent flavin monooxygenase (FMO). KMO has one dicucleotide binding domain, which simply categorizes it as a Class A flavoprotein aromatic hydroxylase
FAD-dependent kynurenine 3-monooxygenase (KMO) catalyzes the conversion of L-kynurenine (L-Kyn) to 3-Hydroxykynurenine (3-HK) in the kynurenine pathway. In the pathway responsible for the catabolism of tryptophan, enzyme KMO regulates the levels of bioactive substances. L-Kyn, is also a substrate to both kynureninase (KYNU) and especially to kynurenine aminotransferase (KAT), which converts L-Kyn to kynurenic acid (KynA), a neuroprotective agent for being the antagonist of NMDA, alpha-7 nicotinic acetylcholine, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, and kainate, and an antioxidant for being the scavenger of several free radical species
the enzyme is involved in the kynurenine pathway (KP) that is the essential metabolic pathway for the catabolism of tryptophan. L-kynurenine (KYN) is the key and first stable intermediate of the KP by a formamidase. There are three possible metabolic fates for KYN, which involve biotransformations with (1) kynurenine aminotransferase (KAT) to form kynurenic acid (KynA), (2) kynureninase to form anthranilic acid, and (3) kynurenine 3-monooxygenase (KMO) to form 3-hydroxykynurnine (3-HK). 3-Hydroxykynurnine (3-HK) further leads to the formation of picolinic acid, 3-HANA, cinnabarinic acid, and quinolinic acid (QUIN). Three metabolites, QUIN, 3-HK, and 3-HANA, have been shown to be neurotoxic
KMO is a flavin-dependent hydroxylase that catalyzes the hydroxylation of L-kynurenine (L-Kyn) to 3-hydroxykynurenine (3-HK) in the kynurenine pathway (KP). The kynurenine pathway (KP) is the major mechanism for tryptophan catabolism with up to 99% of tryptophan being metabolized this way
kynurenine 3-monooxygenase (KMO) regulates the levels of bioactive substances in the kynurenine pathway of tryptophan catabolism and its activity is tied to many diseases. The product of the enzyme reaction, 3-hydroxy-L-kynurenine (3-HK), is a neurotoxic agent that induces apoptosis and damages wide range of cell types. It is further converted to the free-radical generator 3-hydroxyanthranilate (3-HanA) which is then converted to the selective N-methyl-D-aspartate (NMDA) receptor agonist quinolinate
a Rossmann fold simply characterizes a secondary structure with an alternating motif of beta sheets and alpha helices, and is of importance because this domain non-covalently binds the FAD cofactor and also contains the active site of the enzyme for KMO
ScKMO is active without its membrane targeting domain, structure comparisons with the enzymes from Homo sapiens (hKMO) and Pseudomonas fluorescens (pfKMO), overview
the structure of KMO can be realized as three domains: the first domain is where FAD is buried within beta-sheets and alpha-helices, one of which is the long alpha-helix that leads to the C-terminal domain. This helix and a loop that stands above the isoalloxazine rings of FAD define the borders of the active site in this region. The second region contains the residues of alpha-helices and beta-sheets whose side chains set the final border to the active site. Therefore, the active site is contained at the interface of the first and second regions. The third region of PfKMO consists of four alpha-helices while in scKMO and hKMO there are only the two alpha-helices of the transmembrane domain
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CRYSTALLIZATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
crystal structure, in the free form and in complex with the tight-binding inhibitor UPF 648. UPF 648 binds close to the FAD cofactor and perturbs the local active site structure, preventing productive binding of the substrate kynurenine
generation of a C-terminal domain truncated human KMO whose membrane targeting sequence in its C-terminal domain is suggested to be an essential part of its catalysis
enzyme KMO is an important drug target due to its role in regulating the levels of bioactive substances with contrasting effects. For treatment of central nervous related diseases, it is required that enzyme inhibitors should be both blood brain barrier permeable and should not cause hydrogen peroxide as a harmful side product. Molecular dynamics simulations and MM/GBSA calculations, overview
The regulatory function of L-kynurenine 3-hydroxylase (EC 1.14.1.2) for the biosynthesis of pyridine nucleotides in anaerobically and aerobically grown Saccharomyces cerevisiae