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)

We evaluated the efficacies of five treatment procedures for eliminating ascorbate interference in the enzymatic determination of urinary oxalate. Aliquots of urine samples, containing different amounts of added ascorbate and oxalate, were individually subjected to ferric chloride, sodium nitrite, sodium periodate, charcoal, or ascorbate oxidase treatment to eliminate ascorbate interference. Oxalate contents of the urine samples were then determined by a banana oxalate oxidase-horseradish peroxidase-linked assay with 3-methyl-2-benzothiazolinone hydrazone and 3-(dimethylamino)benzoic acid as chromogens. Only those urine samples treated with ascorbate oxidase or charcoal consistently gave recovery of oxalate close to 100%. Treatment with other reagents, though improving the recovery of oxalate, gave inconsistent results. On the basis of these data, we describe procedures for simply and reliably assaying oxalate by using banana oxalate oxidase.
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PMID:Five treatment procedures evaluated for the elimination of ascorbate interference in the enzymatic determination of urinary oxalate. 204 51

Diamine oxidase or its substrates can be measured using a coupled reaction with peroxidase and the chromogen 3-methyl-2-benzothiazolone hydrazone (MBTH) with an appropriate acceptor such as 3-(dimethylamino)benzoic acid (DMAB). This method provides a more rapid and sensitive method of measuring histamine than current colorimetric assays; using this system, histamine was quantitated at concentrations of 10 to 400 mumol/l. The Km of DAO was determined to be 2.9 X 10(-5) M, a lower value than previously reported.
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PMID:An improved spectrophotometric assay for histamine and diamine oxidase (DAO) activity. 393 44

This method was proposed earlier for measuring glucose in a peroxidase-glucose oxidase system but has not been studied for determination of manganese peroxidase (MnP) activity. The assay is based on the oxidative coupling of 3-methyl-2-benzothiazolinone hydrazone (MBTH) and 3-(dimethylamino)benzoic acid (DMAB). The reaction of MBTH and DMAB in the presence of H2O2, Mn2+, and MnP gives a deep purple-blue color with a broad absorption band with a peak at 590 nm. The extinction coefficient is high (53,000 M-1 cm-1), so low MnP activities can be detected. Lignin peroxidase and laccase, usually present in cultures of white rot fungi, gave little or no interference at the concentrations tested. However, slight interference from very high LiP activity may occur at very low MnP activity.
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PMID:Determination of manganese peroxidase activity with 3-methyl-2-benzothiazolinone hydrazone and 3-(dimethylamino)benzoic acid. 807 99

This communication introduces a new spectrophotometric assay for the detection of peroxide generated by Photosystem II (PS II) under steady state illumination in the presence of an electron acceptor. The assay is based on the formation of an indamine dye in a horseradish peroxidase coupled reaction between 3-(dimethylamino)benzoic acid and 3-methyl-2-benzothiazolinone hydrazone. Using this assay, we found that as the O2 evolution activity of PS II-enriched membrane fragments is decreased by treatments which cause the dissociation of the 33 and/or 23 and 16 kDa extrinsic proteins (i.e., CaCl2-washing, NaCl-washing, lauroylcholine-treatment and ethylene glycol-treatment), light-induced peroxide formation increases. Both the losses of O2 evolution and increases in peroxide formation seen under these conditions are reversed by CaCl2 addition, indicating that the two activities originate from the water-splitting site. However, the increased rates of peroxide formation do not quantitatively match the losses in O2 evolution activity. We suggest that a rapid consumption of the peroxide takes place via a catalase/peroxidase activity at the water-splitting site which competes with both the O2 evolution and peroxide formation reactions. The observed peroxide formation is interpreted as arising from enhanced water accessibility to the catalytic site upon perturbation of the extrinsic proteins which then leads to alternate water oxidation side reactions.
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PMID:Increases in peroxide formation by the Photosystem II oxygen evolving reactions upon removal of the extrinsic 16, 22 and 33 kDa proteins are reversed by CaCl2 addition. 2431 98