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SYSTEMATIC NAME
IUBMB Comments
urate:oxygen oxidoreductase
This enzyme was previously thought to be a copper protein, but it is now known that the enzymes from soy bean (Glycine max), the mould Aspergillus flavus and Bacillus subtilis contains no copper nor any other transition-metal ion. The 5-hydroxyisourate formed decomposes spontaneously to form allantoin and CO2, although there is an enzyme-catalysed pathway in which EC 3.5.2.17, hydroxyisourate hydrolase, catalyses the first step. The enzyme is different from EC 1.14.13.113 (FAD-dependent urate hydroxylase).
urate oxidase catalyzes the hydroxylation of uric acid into the metastable product 5-hydroxyisourate in the presence of molecular oxygen as part of the purine degradation pathway. 5-Hydroxyisourate decays slowly to allantoin, a process independent of oxygen and associated with the release of CO
substrate binding involves residues Arg176 and Glu228, that hold the substrate, Phe159 closing one end of the cavity below, and the two residues Asn254 and Thr57, forming another tweezers above the mean plane of the ligand that construct a location where efficient electron transfer can take place at a low energy level via the catalytic triad Thr57, Lys10, and His256
it is proposed that T69 and K9 form a catalytic diad in which K9 deprotonates T69 to allow it to abstract the proton from the N9 position of the substrate to generate the dianion
urate oxidase catalyzes the hydroxylation of uric acid into the metastable product 5-hydroxyisourate in the presence of molecular oxygen as part of the purine degradation pathway. 5-Hydroxyisourate decays slowly to allantoin, a process independent of oxygen and associated with the release of CO
anion-pi interactions are present in the active site of the enzyme and are energetically favorable. Uric acid and 8-azaxanthine are able to interact favorably with cyanide and chloride ions, respectively and both uric acid and 8-azaxanthine react with water
1 h after feeding with ammonium chloride highest expression of urate oxidase in fat body, 6 h after feeding with ammonium chloride highest expression of urate oxidase in malpighian tubules; in fat body 3fold increased expression towards end of blood meal digestion; in malpighian tubule expression induced in response to a blood meal, maximum level 24 h after feeding
1 h after feeding with ammonium chloride highest expression of urate oxidase in fat body, 6 h after feeding with ammonium chloride highest expression of urate oxidase in malpighian tubules; in fat body 3fold increased expression towards end of blood meal digestion; in malpighian tubule expression induced in response to a blood meal, maximum level 24 h after feeding
among the parameters investigated in shaking flask cultures, the pH value of medium and inoculum size has great influence on the recombinant uricase production, the maximum extracellular uricase yield of 2.6 U/ml is obtained in shaking flask culture; at pH 5.5, the extracellular uricase production reaches top of 7.5 U/ml at 58 h, when fermentation is performed at pH 6.5 for 62 h, 14.5 U/ml of extracellular uricase and 23.3 U/ml of intracellular uricase are produced, the total specific uricase production at pH 6.5 is 1.7times of that at pH 5.5; in high density fermentation in YPG medium at 37°C, extracellular uricase activity increases significantly during the first 40 h, highest extracellular uricase level of 52.3 U/ml is obtained after 58 h of induction, as well as the intracellular activity of 60.3 U/ml, after 86 h of fermentation and 58 h of induction, a total uricase activity of 112600 U/l is obtained, the extracellular and intracellular yields of uricase in high cell density fermentation increased by 3.7fold and 3.5fold compared with the batch fermentation; the combined use of fed-batch culture and pH-controlled strategy increases the expression level of uricase significantly, the extracellular uricase production of 52.3 U/ml (approximately 2.1 g/l of protein) is obtained, which is much higher than that produced by recombinant Escherichia coli strains
enzyme activity is 0.06 U/ml at pH 4.0; enzyme activity is 0.09 U/ml at pH 4.5; enzyme activity is 0.11 U/ml at pH 5.0; enzyme activity is 0.21 U/ml with potassium nitrate as nitrogen source; enzyme activity is 0.22 U/ml at pH 10.0; enzyme activity is 0.31 U/ml with ammonium sulfate as nitrogen source; enzyme activity is 0.32 U/ml with sodium glutamate as nitrogen source; enzyme activity is 0.37 U/ml at pH 5.5; enzyme activity is 0.42 U/ml at pH 9.5; enzyme activity is 0.45 U/ml with citric acid as carbon source; enzyme activity is 0.46 U/ml with glucose as carbon source; enzyme activity is 0.46 U/ml with peptone as nitrogen source; enzyme activity is 0.47 U/ml at pH 6.0; enzyme activity is 0.47 U/ml with lactose as carbon source; enzyme activity is 0.49 U/ml with starch as carbon source; enzyme activity is 0.57 U/ml at pH 9.0; enzyme activity is 0.57 U/ml with soybean flour as nitrogen source; enzyme activity is 0.63 U/ml at pH 8.5; enzyme activity is 0.65 U/ml with beef extract as nitrogen source; enzyme activity is 0.67 U/ml with sucrose as carbon source; enzyme activity is 0.69 U/ml with yeast extract as nitrogen source; enzyme activity is 0.72 U/ml at pH 8.0; enzyme activity is 0.78 U/ml with maize milk as nitrogen source; enzyme activity is 0.98 U/ml at pH 6.5; enzyme activity is 1.00 U/ml at pH 7.5; enzyme activity is 1.25 U/ml at pH 7.0; when the strain is cultured at 30°C at pH 7.0 for 30-36 h with of 0.6% corn steep liquor as nitrogen source, the uricase activity peaks at 1.25 U/ml
enzyme activity is 0.06 U/ml at pH 4.0; enzyme activity is 0.09 U/ml at pH 4.5; enzyme activity is 0.11 U/ml at pH 5.0; enzyme activity is 0.21 U/ml with potassium nitrate as nitrogen source; enzyme activity is 0.22 U/ml at pH 10.0; enzyme activity is 0.31 U/ml with ammonium sulfate as nitrogen source; enzyme activity is 0.32 U/ml with sodium glutamate as nitrogen source; enzyme activity is 0.37 U/ml at pH 5.5; enzyme activity is 0.42 U/ml at pH 9.5; enzyme activity is 0.45 U/ml with citric acid as carbon source; enzyme activity is 0.46 U/ml with glucose as carbon source; enzyme activity is 0.46 U/ml with peptone as nitrogen source; enzyme activity is 0.47 U/ml at pH 6.0; enzyme activity is 0.47 U/ml with lactose as carbon source; enzyme activity is 0.49 U/ml with starch as carbon source; enzyme activity is 0.57 U/ml at pH 9.0; enzyme activity is 0.57 U/ml with soybean flour as nitrogen source; enzyme activity is 0.63 U/ml at pH 8.5; enzyme activity is 0.65 U/ml with beef extract as nitrogen source; enzyme activity is 0.67 U/ml with sucrose as carbon source; enzyme activity is 0.69 U/ml with yeast extract as nitrogen source; enzyme activity is 0.72 U/ml at pH 8.0; enzyme activity is 0.78 U/ml with maize milk as nitrogen source; enzyme activity is 0.98 U/ml at pH 6.5; enzyme activity is 1.00 U/ml at pH 7.5; enzyme activity is 1.25 U/ml at pH 7.0; when the strain is cultured at 30°C at pH 7.0 for 30-36 h with of 0.6% corn steep liquor as nitrogen source, the uricase activity peaks at 1.25 U/ml
rasburicase causes enzymatic degradation of uric acid within blood, plasma and serum samples at room temperature, the genetic absence of this molecule in humans and its proteic nature together with poor accuracy in purifi cation and a slow production process confer a high immunogenicity to the compound, leading to elevated rate of hypersensivity reactions; rasburicase does not interact with allopurinol, cytarabine, methylprednisolone, methotrexate, mercaptopurine, thioguanine, etoposide, daunorubicin, cyclophosphamide, or vincristine; rasburicase maintains the same mechanism of action as the non-recombinant form of urate oxidase, but simply shows a significantly lower reaction rate; repeated use of rasburicase increases risk of hypersensitivity reactions: skin rashes (1.4%), urticaria, bronchospasm (1%), dyspnea, hypoxemia, and anaphylactic shock (1%)
yield of recombinant uricase is significantly improved by the combined use of a high cell-density cultivation technique and a pH control strategy of switching culture pH from 5.5 to 6.5 in the induction phase
the unmodified uricase has a pH optimum of slightly below pH 9.2 which is not altered by modification with NHS esters of monomethoxy-poly(ethylene glycol)-5000 or monomethoxy-poly(ethylene glycol)-350
free uricase shows at least 50% relative activity between pH 6.5 and 9.5, around pH 7.5, free uricase remains 81.16% of its maximum activity, while the uricase loaded in the lipid vesicles remains almost the same high activity (178.26%) as its optimum activity (179.72%)
no uricase is detected in mycelium grown in minimal medium containing NH4Cl as sole nitrogen source. Uricase activity is increased 10fold to 40fold under derepression conditions and is induced by exogenous uric acid
activity increases once the haustorium has differentiated after Uromyces phaseoli infection. A up-regulation of urate oxidase gene expression occurs at the post-transcriptional level rather than an overexpression of the urate oxidase gene. A general pathogenic effect and host urate oxidase, and purine pool depauperation
determined by X-ray diffraction measurements, the AgUOX-native structure is solved by molecular replacement using the program AmoRe, pairs of dimers are stacked face-to-face to form a tetramer
determined by gel filtration, tunnel-shaped homotetramer, each of the 4 active sites in UOX is formed by residues from 2 subunits and located at the subunit-subunit interface
4 * 000, SDS-PAGE, homotetrameric uricase in water dissociates into inactive homodimers that can form active homotetramers again in solutions of high ionic strength
4 * 000, SDS-PAGE, homotetrameric uricase in water dissociates into inactive homodimers that can form active homotetramers again in solutions of high ionic strength
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Crystallization/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
crystallizations are performed using the hanging-drop vapour-diffusion method at 19.9°C, structures of crystals soaked with the substrate uric acid, the inhibitor 8-azaxanthin and allantoin are determined at 1.9-2.2 A resolution, 2 homotetramers comprise the asymmetric crystallographic unit, each subunit contains 2 T-fold domains of topology, which are usually found in purine- and pterin-binding enzymes, the uric acid substrate is bound tightly to the enzyme by interactions with Arg180, Leu222 and Gln223 from one subunit and with Thr67 and sp68 of the neighbouring subunit in the tetramer
crystals of about a few tens of micrometres in size, which is nucleated previously in crystallization batch containing 5% PEG 8000, 100 mM NaCl, 8 mg/ml uox-substrate complex and 100 mM Tris-HCl pH 8.5, are used as seeds and their size and quality are further improved using a temperature-control device, large crystals of Uox, co-crystallized with its substrates analogues 8-azaxanthine, 9-methyluric acid or the natural substrate in the presence of cyanide (0.5-2 mg/ml), and soaks with the natural substrate in the absence of cyanide, diffracting to high resolutions are obtained, in the presence of different inhibitors, the crystal form of Uox has a body-centred orthorhombic symmetry and one of the largest primitive unit-cell volumes (a: 80 A, b: 96 A, c: 106 A)
ligand-free Uox crystallized with NH4Cl and 15% (w/v) PEG 8000, ligand-free Uox crystallized in water with 10% (w/v) PEG 8000, ligand-free Uox crystallized with NaCl and 15% (w/v) PEG 8000, ligand-free Uox crystallized with (NH4)2SO4 and 15% (w/v) PEG 8000, ligand-free Uox crystallized with NaCl and 8% PEG 8000, ligand-free Uox crystallized with KCl and 10% (w/v) PEG 8000, and Uox complexed with 8-azaxanthine and crystallized with NaCl and 10% (w/v) PEG 8000, in 50 mM Tris buffer pH 8.0
recombinant enzyme in complex with inhibitor 8-azaxanthine in presence of O2 or Cl-, batch technique at room temperature, 10-15 mg/ml protein with an excess of 0.5-2 mg/ml of 8-azaxanthin in 50 mM Tris/HCl, pH 8.5, in the presence of 5-8% w/v PEG 8000 and 0.05 M NaCl, 24-48 h, X-ray diffraction structure determination and analysis at 1.6-1.7 A resolution
sitting-drop vapour-difusion method. Four different crystal forms of Uox are analyzed. In the presence of uracil and 5,6-diaminouracil crystals usually belong to the trigonal space group P3(1)21, the asymmetric unit of which contains one tetramer of Uox. Chemical oxidation of 5,6-diaminouracil within the protein may occur, leading to the canonical (I222) packing with one subunit per asymmetric unit. Coexistence of two crystal forms, P2(1) with two tetramers per asymmetric unit and I222, is found in the same crystallization drop containing another inhibitor, guanine. A fourth form, P2(1)2(1)2 with one tetramer per asymmetric unit, results in the presence of cymelarsan, an additive
homology modeling of monomeric enzyme. The highly conserved residue Gly290 could interact with Asn262 and His264. Residue substitutions near Gly290 may affect its spatial orientation and result in changes in catalysis.Gly290 is likely to participate in the structure of the active site and to be involved in oxygen-binding
UOX is deactivated at different protein concentrations at 45°C in 20 mM phosphate containing 0.15 M NaCl, 0.01 mg/ml UOX is deactivated much faster than its counterparts at concentrations of 0.1 and 1.0 mg/ml
in case of uricase entrapped in lipid vesicles, the remaining activity keeps more than 90% during the pH of 7.0-9.5, and the maximum remaining activity is 98.04% at pH 8.0 when incubated at 40°C or 40 min. For the free uricase, the maximum remaining activity is 86.59% at pH 8.5 when incubated at 40°C or 40 min
uricase activity in 50 h culture broth with pH values of 5.5 and 6.0 decreases more rapidly than that in cultures with pH values of 6.5 and 7.0, at pH 5.5, about 78% of initial uricase activity is lost within 25 h, under the same conditions, more than 85% of initial uricase activity remains in culture broth of pH 6.5 and 7.0, uricase activity in 66 h culture broth with pH 7.0 degrades much more rapidly than that in samples from 50 h culture, while for pH 6.5, the uricase is still stable, loss of uricase activity is caused by the degradation in acidic environment by proteases secreted by the host cells or releases from host cell lyses, low pH may cause instability of uricase
about 80% relative activity at 10°C, about 85% relative activity at 20-30°C, about 90% relative activity at 37°C, about 40% relative activity at 40°C, about 30% relative activity at 50°C, about 20% relative activity at 60°C, about 10% relative activity at 70°C, and no activity at 80°C after 30 min incubation
uricase covalently linked to monomethoxypoly(ethylene glycol) N-leucine-OSu-uricase and branched monomethoxypoly(ethylene glycol) N-leucine-OSu-uricase 50% loss of activity
uricase entrapped in lipid vesicles at enzyme concentrations of 0.005 and 0.1 mg/ml shows no loss of activity after 5 h at 55°C. Uricase entrapped in lipid vesicles at enzyme concentrations of 0.01 mg/ml shows about 35% loss of activity after 5 h at 55°C. Uricase entrapped in lipid vesicles at enzyme concentrations of 0.005 mg/ml shows about 50% loss of activity after 5 h at 55°C. The free uricase at 0.005 mg/ml is rapidly deactivated to about 30% of the initial activity within an incubation time of 2 h, while more than 70% of the initial enzyme activity remains for the uricase at 0.1 mg/ml in the identical incubation time
at 40°C in sodium borate buffer at pH 9.2, the unmodified uricase shows a thermo-inactivation half-life of about 40 h. Modification of the uricase by monomethoxy-poly(ethylene glycol)-350 slightly enhances its thermostability, and modification by monomethoxy-poly(ethylene glycol)-5000 increases its thermo-inactivation half-life to over 85 h at 40°C in sodium borate buffer at pH 9.2
thermal deactivation of recombinant UOX at neutral pH is associated with the loss of intersubunit hydrogen bonds, subunit is unstable at room temperature and unfolds rapidly at 100°C, tetramer has significantly higher stability than its subunit
the main phase of thermal inactivation follows an irreversible two-state mechanism, with loss of about 20% of the helical structure, loss of the majority of the tertiary structure, and partial exposure of tryptophan residues to solution being approximately concurrent with activity loss. This process results in the formation of aggregated molten globules. In addition, a rapid reversible denaturation phase occurs that is not completely coupled to the main phase. Enzyme inactivation is inhibited by the presence of glycerol and trimethylamine oxide. NaCl destabilizes the enzyme at elevated temperature
at the physiological pH, significant increase of enzyme activity is found for the uricase entrapped in the lipid vesicles (1.8times that of free uricase) at their respective optimum pH. Free uricase shows rapid decrease in its enzymatic activity with a half life of less than 20 min when incubated with trypsin. Uricase entrapped in the lipid vesicles gradually loses its activity but still 50% of the original activity remains after 60 min (remaining activity is 7.32% in case of free uricase)
uricase is reversibly inactivated in solutions of low ionic strength (like during dialysis against water). After incubation for 2 h in 100 mM sodium chloride in water at 4°C, the dialysis-inactivated uricase shows about 70% of the maximal specific activity. After incubation for 2 h in 100 mM Tris-HCl pH 8.0 plus 100 mM NaCl at 4°C, the dialysis-inactivated uricase shows about 90% of the maximal specific activity. After pre-incubation for 0.5 h in sodim borate plus 100 mM NACL at 25°C followed by the direct addition of urate to measure its activity, the dialysis-inactivated uricase shows about 80% of the maximal specific activity
the residual recombinant UOX activity in the presence of DMSO is significantly higher than that in pure H2O, the residual UOX activity increases in response to the increase in the DMSO concentration up to 20%, further increase in DMSO concentration (50-70%) results in significant UOX deactivation
the residual recombinant UOX activity in the presence of methanol is significantly higher than that in pure H2O, the residual UOX activity increases in response to the increase in the methanol concentration up to 20%, further increase in methanol concentration (50-70%) results in significant UOX deactivation
developing of a method for genetically incorporating p-azido-L-phenylalanine into target protein in Escherichia coli in a site-specific manner utilizing a tyrosyl suppressor tRNA/aminoacyl-tRNA synthetase system, substitution of p-azido-L-phenylalanine for F170 or F281 in urate oxidase, optimization of the system by adding a Shine-Dalgarno sequence and tandem suppressor tRNA in order to increase the expression levels of tyrosyl suppressor tRNA and aminoacyl-tRNA synthetase
expression in Escherichia coli, Escherichia coli harboring pUOD1 produces 20fold higher uricase than the original Arthrobacter strain, even without an inducer
uricase production by the recombinant Hansenula polymorpha strain MU200 harboring Candida utilis uricase gene under the control of methanol oxidase promoter using Saccharomyces cerevisiae alpha-factor signal peptide as the secretory sequence
using the recombinant DNA technique, enzyme is obtained from a genetically modified Saccharomyces cerevisiae strain that expresses urate oxidase cDNA, cloned from a strain of Aspergillus flavus
mutant enzyme has a maximal velocity of 3% of the wild-type value. Ionization at pH 6.4 that is observed with the wild-type enzyme is absent in the mutant. The KM-value for urate is 5fold higher than that of the wild-type enzyme
replacement with the corresponding residues of human enzyme. Catalytic efficiency is higher than in wild-type, but below the efficiency of mutant R291K/A296V/A301S/K303R
mutant enzyme has a maximal velocity of 0.4% of the wild-type value. Ionization at pH 6.4 that is observed with the wild-type enzyme is absent in the mutant. The KM-value for urate is 1.5fold higher than that of the wild-type enzyme
uricase covalently linked to monomethoxypoly(ethylene glycol) N-leucine-OSu, branched monomethoxypoly(ethylene glycol) N-leucine-OSu or poly(N-acryloylmorpholine)-OSu last longer in blood
the recombinantly expressed porcine enzyme, with a C-terminal sequence from baboon uricase, is applicated to patients with refractory gout, due to a mutation in the uricase gene, by intravenous injection in a PEG-bound form, pharmacokinetics and pharmacodynamics, safety, and efficacy of the treatment in a clinical trial, overview
urate oxidase is a potential therapeutic protein in the prevention and treatment of tumor lysis syndrome and hyperuricemia. However, its severe immunogenicity limits its clinical application. Engineering site-specific modifications of keto groups in urate oxidase by using evolved Methanocaldococcus jannaschii aminoacyl-tRNA synthetase(s)/suppressor tRNA pairs reduces its antigenicity. The mutated uricase exhibits decreased antigenic properties, while its catalytic activities remain unchanged
high-yield expression of uricase in Escherichia coli and establishment of an efficient three-step protein purification protocol. The purity of the recombinant protein is more than 98% and the specific activity is 38.4 IU/mg
a colorimetric 96-well microtiter plate assay for the determination of urate oxidase activity and its kinetic parameters based on hydrogen peroxide quantitation. The general advantages of the colorimetric assay are easy handling of large amounts of samples at the same time, the possibility of automation, and the need for less material
modified colorimetric assay for uricase activity in flexible 96-well microtiter plates using the uricase/uric acid/horseradish peroxidase/4-aminoantipyrine/3,5-dichloro-2-hydroxybenzene sulfonate colorimetric reaction. The method is much more efficient than the conventional ones and greatly reduces assay time from 4 days to less than 20 h
development of an urate-selective microbial biosensor cells of the recombinant thermotolerant methylotrophic yeast Hansenula polymorpha as biorecognition element. The UOX producing cells are coupled to horseradish peroxidase and immobilized on graphite electrodes by physical entrapment behind a dialysis membrane. A high urate selectivity with a detection limit of about 8 microM is found
uricase is an important medical enzyme which can be used to determine urate in clinical analysis, to therapy gout, hyperuricemia, and tumor lysis syndrome
treatment od tumor lysis syndrome, recombinant urate oxidase is effective in reducing uric acid and preventing uric acid accumulation in patients with hematologic malignancies with hyperuricemia or at high risk of developing it, rasburicase represents an effective alternative to allopurinol to promptly reduce uric acid levels, improve patients electrolyte status, and reverse renal insufficiency
determination of the urate concentration in blood and urine is required for the diagnosis of gout as urate accumulation is a causative factor of gout in humans