Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.11.1.7 (peroxidase)
 65,474 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A uricase-peroxidase coupled system, for the determination of uric acid, applied to a CentrifiChem-500 centrifugal fast analyser is described. Relatively large amounts of ascorbic acid, due to the inclusion of an ascorbate oxidase urine diluent, and hemoglobin appear not to interfere with the procedure while the incorporation of potassium ferrocyanide into the reagents has led to the near-total elimination of bilirubin interference. The incubation period is relatively short compared with other similar procedures and the one reagent system has made the procedure simple to perform. The use of sodium 2-hydroxy-3,5-dichlorobenzenesulfonate and 4-aminoantipyrene in the oxidative coupling reaction has incorporated the advantages of increased sensitivity, over phenol-4-aminoantipyrene systems, as well as the amenability of the reagent towards lyophilization or "dry-fill".
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PMID:The application of a sensitive uricase-peroxidase couple reaction to a centrifugal fast analyser for the determination of uric acid. 729 93

A new direct colorimetric procedure for uric acid assay in serum or urine is described, utilizing a 3,5-dichloro-2-hydroxybenzene sulfonic acid/4-aminophenazone chromogenic system in the presence of horseradish peroxidase and uricase from Aspergillus flavus. This chromogen system has a high absorptivity, affording useful results with sample/reagent volume ratios as low as 0.025. The procedure is applicable to serum, plasma, or diluted urine. A single working reagent is used; the reaction is complete in less than 15 min at room temperature. The red dye formed is measured at 520 nm; a blank sample measurement is not needed. The standard curve for the method is linear for uric acid concentrations up to 1500 mumol/L. Average analytical recovery of uric acid in human sera and urine exceeded 99%; within-run and between-run precision studies showed CV's of less than or equal to 1.2 and less than or equal to 2.2%, respectively. The new procedure correlated well with the uricase/catalase and uricase/ultraviolet methods. The method is suitable for automation.
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PMID:Use of 3,5-dichloro-2-hydroxybenzenesulfonic acid/4-aminophenazone chromogenic system in direct enzymic assay of uric acid in serum and urine. 735 68

A reliable method for the determination of uric acid in plasma or serum is described. The hydrogen peroxidase developed in the uricase reaction is used, together with peroxidase, for the coupling of sulphonated dichlorophenol and 4-aminoantipyine to a red dye. The difference in absorbance at 515 nm before and after addition of uricase is measured. Of the components tested for interference some gave rise to falsely lowered values. Reagents are cheap and the high molecular absorption coefficient of the red dye permits the use of small sample volumes.
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PMID:Determination of uric acid with uricase and peroxidase. 735 49

In the Belgian national external quality assessment scheme, we observed significantly lowered recoveries for urate in the group of Beckman Synchron users in comparison with the overall median values of the uricase/peroxidase colorimetric methods. These effects were linked to control sera of some manufacturers and we could demonstrate that these sera contained large amounts of pyridoxal-5-phosphate (PLP) as activator for transaminases. By spiking normal human serum with increasing PLP concentrations from 62.5 to 1000 mumol l-1, we observed a decrease in the urate recovery from 125 mumol l-1 (-11%). At 1000 mumol l-1 PLP, only 40% of the urate concentration was measured. An explanation for this effect was found in the polychromatic corrections of the Beckman Sychron system only applied with the Beckman urate method. This study demonstrates that EQAS organizers must carefully distinguish in their peer groups, not only the analytical principle and the measurement equipment, but also the reagent origin. Finally, the use of EQA control sera without PLP addition is strongly recommended if these sera are intended to be used as accuracy controls in EQA schemes including Beckman Synchron users.
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PMID:Factitiously low urate recoveries in control sera with the Beckman Synchron Systems. 780 82

In order to investigate the permeability properties of rat-liver peroxisomes in situ, we selectively permeabilized hepatocytes with digitonin in a medium mimicking the cytosol. This system permitted us to study the latency of peroxisomal oxidases by means of measurement of their activities in permeabilized compared to disrupted hepatocytes. The activity of peroxisomal oxidases was studied using three different methods: (1) measurement of the oxidase-mediated production of H2O2 in a system containing homovanillic acid, horseradish peroxidase and azide; (2) measurement of the rate of substrate utilization or product formation; (3) measurement of the production of H2O2 via the peroxidative action of catalase in the presence of an excess of methanol. The results obtained depended on which system was used to measure the activity of the different oxidases. Our observations lead us to conclude that method 1 cannot be used for latency studies, whereas methods 2 and 3 are suitable under defined circumstances. Based on the results of methods 2 and 3, we conclude that urate oxidase, L-alpha-hydroxyacid oxidase A and D-amino acid oxidase show no structure-linked latency in digitonin-permeabilized hepatocytes, suggesting that the substrates for these enzymes permeate freely through the peroxisomal membrane.
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PMID:Permeability properties of peroxisomes in digitonin-permeabilized rat hepatocytes. Evidence for free permeability towards a variety of substrates. 790 78

We developed and evaluated an assay for serum uric acid based on the uricase (EC 1.7.3.3)-catalase (EC 1.11.1.6)-formaldehyde dehydrogenase (FADH, EC 1.2.1.46) method coupled with formate dehydrogenase (formate:NAD oxidoreductase, FDH, EC 1.2.1.2). Formate dehydrogenase from Pseudomonas oxalaticus catalyzes the formation of NADH from formate produced by FADH. Owing to the NADH and formate oxidase activity of the FDH itself, the full reaction curve is not linear, but gradually decreases. The formation of NADH is not stoichiometric with formate removal, but is strictly proportional to it. To overcome this decrease of extinction, we added hydroxylamine hydrochloride to the FDH. The sensitivity of the full reaction in the presence of FDH was about 1.8 times that without FDH. Analysis with a Cobas Bio centrifugal analyzer revealed a linearity of up to 3.56 mmol/L. The uricase-catalase-alcohol dehydrogenase method correlated well with the uricase-peroxidase-chromogen method. Our method is more sensitive than other methods.
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PMID:A sensitive determination of uric acid in serum using uricase/catalase/formaldehyde dehydrogenase coupled with formate dehydrogenase. 807 73

The dominant position among oxidoreduction processes in peroxisomes is ascribed to catalase, a number of aerobic oxidases, and Cu,Zn-superoxide dismutase. The peroxidase reaction of catalase requires substrates for hydrogen donation, other than H2O2, e.g. alcohols, aldehydes, formic acid. The peroxisomes contain an alternative system of beta-oxidation of higher carboxylic acids which in some types of plant cells is functionally very closely associated with the glyoxylate cycle. Regarding the role of peroxisomes in the metabolism of carboxylic acids, a very important finding has taken place, namely that besides acyl-CoA synthetase which is specific for long chains, the peroxisomes contain still another enzyme which allows the synthesis of CoA esters of fatty acids with very long chains. It is assumed that the entry of acyl-CoA esters or fatty acids into the perxisomes is performed by means of pores in membranes or acyl-carnitine transferases. Peroxisomes oxidize a very wide scale of substrates and contain several types of acyl-CoA oxidases: palmitoyl-CoA oxidase, pristanoyl-CoA oxidase, trihydroxy-coprostanoyl-CoA oxidase. The second and third reactions of peroxisomal beta-oxidation are catalyzed by the so-called three-functional enzyme, the activities of which are identical to those of 2-enoyl-CoA hydratase, beta-hydroxyacyl-CoA dihydrogenase and enoyl-CoA isomerase. The peroxisomes sufficiently oxidize dicarboxylic acids with a higher number of carbons beginning with the adipic acid. The peroxisomal system of beta-oxidation is utilized in metabolism of prostaglandins, pristanic acid-being the product of phytanic acid alpha-oxidation, and cholesterol. Several enzymatic activities needed for the synthesis of cholesterol partially take place in peroxisomes. The peroxisomes represent a decisive compartment for the initial phases of synthesis of plasmalogens. They contain the following enzymes: NAD(+)-glycerol-P-dehydrogenase, dihydroxyacetone-3-P-acyl-transferase, alkyl-dihydroxyacetone-P synthetase and acyl/alkyl-dihydroxyacetone-P reductase. The metabolism of amino acids takes place under the effect of peroxisomal enzymes--oxidase of diamino acids, D-aspartate oxidase, oxidase of L-pipecolic acid and alanine-glyoxylate aminotransferase. Only a few published sources consider it obvious that liver peroxisomes participate in degradation of spermine and spermidine. Polyamine oxidase oxidizes spermine resulting in the origin of spermidine and 3-aminopropionaldehyde, and spermidine is oxidized to putrescine and 3-aminopropionaldehyde. Peroxisomes in many phylogenetically lower animal species enable the break down of purine bases to urea and glyoxylic acid. In phylogenetically higher primates and in man, the activities of urate oxidase in peroxisomes are absent. (Fig. 14, Ref. 166).
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PMID:The role of peroxisomes in intermediary metabolism. 855 58

Peroxisome proliferators cause a rapid and coordinated transcriptional activation of genes encoding the enzymes of the peroxisomal beta-oxidation pathway in rats and mice. Cis-acting peroxisome proliferator responsive elements (PPREs) have been identified in the 5'-flanking region of H202-producing rat acyl-CoA oxidase (ACOX) gene and in other genes inducible by peroxisome proliferators. To gain more insight into the purported nonresponsiveness of human liver cells to peroxisome volume density and in the activity of the beta-oxidation enzyme system, we have previously cloned the human ACOX gene, the first and rate-limiting enzyme of the peroxisomal beta-oxidation system. We now present information on a regulatory element for the peroxidase proliferator-activated receptor (PPAR)/retinoid X receptor (RXR) heterodimers. The PPRE, consists of AGGTCA C TGGTCA, which is a direct repeat of hexamer half-sites interspaced by a single nucleotide (DR1 motif). It is located at -1918 to -1906 base pairs upstream of the transcription initiation site of this human ACOX gene. This PPRE specifically binds to baculovirus-expressed recombinant rat PPAR alpha/RXR alpha heterodimers. In transient transfection experiments, the maximum induction of luciferase expression by ciprofibrate and/or 9-cis-retinoic acid is dependent upon cotransfection of expression plasmids for PPAR alpha and RXR alpha. The functionally of this human ACOX promoter was further demonstrated by linking it to a beta-galactosidase reporter gene or to a rat urate oxidase cDNA and establishing stably transfected African green monkey kidney (CV1) cell lines expressing reporter protein. The human ACOX promoter has been found to be responsive to peroxisome proliferators in CV1 cells stably expressing PPAR alpha, whereas only a basal level of promoter activity is detected in stably transfected cells lacking PPAR alpha. The presence of a PPRE in the promoter of this human peroxisomal ACOX gene and its responsiveness to peroxisome proliferators suggests that factors other than the PPRE in the 5'-flanking sequence of the human ACOX gene may account for differences, if any, in the pleiotropic responses of humans to peroxisome proliferators.
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PMID:Identification of a peroxisome proliferator-responsive element upstream of the human peroxisomal fatty acyl coenzyme A oxidase gene. 856 72

It has been suggested that achieving a chromogenic endpoint with an absorbance read at 600 nm or greater will reduce the degree of spectral interference in many colorimetric methods. We have examined a uricase/peroxidase-based system utilising a novel oxygen acceptor (azure-D2) as chromogen which produces a chromophor with an absorbance which can be measured at 600 nm (Synermed). Results (median, range, mumol/l) obtained on patient sera (n = 113) using the Synermed method (297; 38-847) were lower than those obtained using a 293 nm uricase method (Du Pont Ltd., 312; 62-874) (p < 0.001, Synermed = -16.709 + 1.0065 Du Pont). Within- and between-batch CV's were < 3% in all cases. Results obtained in one external quality assessment scheme (WEQAS) were significantly lower (p < 0.001) than the method group mean (Synermed = -17.298 + 1.0056 WEQAS) but in a second scheme (NEQAS) results did not differ significantly (p > 0.05) from the method group mean (Synermed = -29.315 + 1.0570 NEQAS). Bilirubin had a negative effect (p < 0.0001; 300 mumol/l producing a 23 mumol/l reduction in uric acid) and haemoglobin had a small positive effect (p < 0.05; 5 g/l increasing uric acid by 8 mumol/l) on the assay. Lipaemia did not interfere (p > 0.05) but both ascorbic acid (100 mumol/l reducing uric acid by 68 mumol/l) and N-acetylcysteine (3 mmol/l reducing uric acid by 95 mumol/l) had significant negative effects (p < 0.0001 in both cases). Uraemic serum had no effect on the assay (p > 0.05) but serum storage for 72 hours at room temperature resulted in a significant (p < 0.0005) increase in measured uric acid. The Synermed method is a precise and accurate assay for serum uric acid. However, although generally showing low levels of spectral interference, chemical interferences in the assay from antioxidant components of serum may be problematic. This paper shows that the use of longer wavelengths of detection can reduce the significance of common spectral interferences.
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PMID:Use of azure-D2 for the measurement of uric acid in serum. 861 69

Urate oxidase from Candida utilis, an enzyme containing an essential thiol, was examined for its sensitivity to lactoperoxidase, an oxidant present in breast milk. Upon exposure to a system composed of lactoperoxidase, hydrogen peroxide and bromide at moderately alkaline pH, the urate oxidase exhibited comparable activity to the untreated enzyme; but upon exposure at moderately acidic pH, it lost its activity completely. Thus the lactoperoxidase-H2O2-bromide system significantly inactivated urate oxidase only at moderately acidic pH. This inactivation was prevented by the presence of N-acetylmethionine, a methionine analogue, or glutathione, which is a thiol compound analogous to an amino acid, indicating that it was probably due to the oxidation and damage of the methionine residue and/or the thiol group in the urate oxidase by the lactoperoxidase system, that loss of catalytic activity of the urate oxidase occurred.
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PMID:Inactivation of urate oxidase by a system composed of lactoperoxidase, hydrogen peroxide and bromide. 963 2


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