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

Human saliva contains a high peroxidase activity that can be estimated spectrophotometrically with the hydrogen donor p-phenylenediamine and the substrate hydrogen peroxide from 20 mul of material. The pH optimum of the enzyme with citrate-phosphate buffer is 5.5. After microanalytical isoelectric fractionation 3 main isoenzyme components at pI 8.6, 6.5 and 4.3, and a number of isoenzyme subfractions at pI 9.5, 7.3 and 3.8 are detectable. In 3 patients with the juvenile form of neuronal ceroid-lipofuscinosis (type Spielmeyer-Vogt), in which a deficiency of leukocyte peroxidase had been reported by other authors, both the total activity of saliva peroxidase and the activity of individual isoenzymes were found to be within normal limits. These findings are not consistent with a generalized peroxidase deficiency in this disease.
Clin Biochem 1976 Apr
PMID:Human saliva peroxidase: microanalytical isoelectric fractionation and properties in normal persons and in cases with neuronal ceroid-lipofuscinosis. 0 36

To produce a 125I-labelled glucagon suitable for radioligand assays, we studied the influence of variations in the lactoperoxidase iodination method. Both the degree of iodine substitution and the formation of monoiodo- or diiodo-tyrosines were pH dependent. The substitution increased and the diiodo-/monoiodotyrosine ratio decreased when pH increased. These two factors affected the immunoreactivity of the iodoglucagon relatively independently of each other. It was found that iodination at pH 10.0 with an average of 0.3 gatom I/mol glucagon resulted in 125I-labelled glucagon with higher immunoreactivity and stability than that produced at the conventional pH 7.5 and 8.5.
Clin Chim Acta 1976 Jun 01
PMID:Improved radioiodination of glucagon with the lactoperoxidase method. Influence of pH on iodine substitution. 0 74

Synthetic porcine secretion was labelled by the conjugation-labelling method of Bolton & Hunter, the lactoperoxidase method, the gaseous diffusion method, and the chloramine-T method. The chloramine-T technique was adapted as routine method. Ten mug (3.27 nmol) peptide was reacted with 5 mCi of Na125I at a concentration of chloramine-T of 1.3 mmol/l. Synthetic secretin was suitable for labelling for at least eight months when stored as dry matter in nitrogen-filled glass ampoules. Purification and separation of labelled from unlabelled hormone was carried out by gel-permeation chromatography on Sephadex G-50 superfine. The labelled preparation had a specific radioactivity of 405 +/- 33 muCi/nmol (mean +/- SEM., n = 9) and was unable for six days. 6-tyrosyl-secretin took more iodine compared to porcine synthetic secretin but had lower immunoreactivity with all antisera tested.
Scand J Clin Lab Invest 1976 Nov
PMID:Preparation of 125I-labeled synthetic porcine secretin for radioimmunoassay. 1 92

A new enzymatic method for the determination of serum pseudo-cholinesterase activity is described. Choline, which is liberated from benzoylcholine as substrate by cholinesterase, is oxidized by choline oxidase to betaine with the simultaneous production of hydrogen peroxide, which oxidatively couples with 4-aminoantipyrine and phenol in the presence of peroxidase to yield a chromogen with maximal absorbance at 500 nm. The calibration curve is linear up to 1500 units per liter of serum. The method is reproducible, and the results correlate well with those obtained by the method using butyrylthiocholine as substrate and 5,5'-dithiobis-(2-nitrobenzoic acid) as color reagent.
Clin Chim Acta 1977 Oct 01
PMID:New enzymatic assay of cholinesterase activity. 2 Feb 53

Most of the currently used enzyme-immunological tests employ horse radish peroxidase as a marker enzyme. A new method is described for the determination of extremely small quantities of peroxidase. This largely prevents the inactivation of the peroxidase by H2O2 and thereby permits a much longer incubation time. In the presence of 25 mmol/l phenol, 2 mmol/l 4-amino-antipyrin and 0.8 mmol/l H2O2, peroxidase catalyses the formation of a red quinonimine, whose increase in adsorption is directly proportional to the enzyme concentration.
J Clin Chem Clin Biochem 1977 Dec
PMID:[Enzyme-immunological tests: determination of the activity of peroxidase with the aid of the "Trinder reagent" (author's transl)]. 2 80

A rapid electrochemical measurement of blood ethanol is proposed. Alcohol is oxidized by NAD+ in the presence of alcohol dehydrogenase; and the NADH produced is aerobically oxidized by horseradish peroxidase. The rate of depletion of buffer-carried oxygen, which is directly proportional to the alcohol concentration in the sample, is amperometrically monitored with a membrane oxygen-sensing electrode. Only a 5-microliter sample of whole blood is required, with no deproteinization, incubation, extraction, or dilution. Results, obtained in less than 1 min, correlate well with those obtained by gas-chromatographic and spectrophotometric methods.
Clin Chem 1978 Apr
PMID:Enzymatic determination of blood ethanol, with amperometric measurement of rate of oxygen depletion. 2 44

A procedure is described for the determination of plasma or serum haemoglobin employing the peroxidase activity of the haemoprotein using 2,2'-azino-di-(3-ethyl-benzthiazolinsulphonate-6) as chromogen. The method gives equal results for free haemoglobin, methaemoglobin and haemoglobin complexed to haptoglobin. It is designed to measure haemoglobin in the range 0--12 mumol/l. The peroxidase activity of myoglobin is similar to that of haemoglobin, whereas haemin in free solution, bound to haemopexin or to albumin (methaemalbumin) shows much lower activity. The precision within run is satisfactory, +/- 5%.
Scand J Clin Lab Invest 1978 Oct
PMID:Determination of plasma or serum haemoglobin by peroxidase activity employing 2,2'-azino-di-(3-ethyl-benzthiazolinsulphonate-6) as chromogen. 3 Jan 65

A rapid, sensitive and reliable method to measure lactate in blood is described. The method is based on the enzymatic oxidation of lactate to pyruvate in the presence of nicotinamide adenine dinucleotide (NAD+) and lactate dehydrogenase (LDH). The reaction product, NADH, is then oxidized by molecular oxygen, carried in the buffered reagent medium, in the presence of horeseradish peroxidase and other cofactors. The maximum rate of oxygen depletion, which is directly proportional to the amount of lactate ion present in the sample, is amperometrically monitored by a membrane oxygen electrode. No sample pretreatment is required in the present procedure other than dilution, and a comparison study between the described method and a spectrophotometric method shows good correlation.
Clin Chim Acta 1979 Feb 01
PMID:A coupled enzymatic method to measure blood lactate by amperometric monitoring of the rate of oxygen depletion with a Clark oxygen electrode. 3 77

The reaction of the two substrates hydrogen peroxide and ABTS with horseradish peroxidase was studied kinetically. Enzyme activity was determined as a function of substrate concentration and pH. Michaelis constants were determined for the two substrates at various pH values. It was found that the affinity of the enzyme for ABTS decreases with increasing pH, and that with higher ABTS concentrations the pH optima of the reaction are shifted towards neutrality. Maximal rate is reached at pH 4.2 with an ABTS concentration of 2 mmol/l. For hydrogen peroxide the data show that the dissociated O2H- is the proper substrate, its affinity for the enzyme being independent of pH. The two substrates show competitive binding to the peroxidase, and each therefore influences the binding constant of the other. A procedure is proposed which allows the determination of peroxidase down to a concentration of 10 ng/l or 2.5 x 10(-13) mol/l.
J Clin Chem Clin Biochem 1979 Jan
PMID:[Horseradish peroxidase: a study of the kinetics and the determination of optimal reaction conditions, using hydrogen peroxide and 2,2'-azinobis 3-ethylbenzthiazoline-6-sulfonic acid (ABTS) as substrates (author's transl)]. 3 27

Glucose oxidase immunoenzymatic localization provides a simple way to show antigens in mammalian tissues, with no need for the quenching of endogenous nonspecific staining. The method is useful for the demonstration of many antigens in formalin-fixed, paraffin-embedded tissues. Improvement of this technic by the use of p-nitro blue tetrazolium chloride (NBT) as the disclosing reagent provides a stable, finely grained localization not possible with the previously used thiazolyl blue (MTT). The described modification makes available an ideal immunoenzymatic stain for the study of tissues at the level of the light microscope. This stain is especially useful for the examination of tissues with hemorrhagic or inflammatory lesions, since there is no endogenous background staining. Slides are permanent, and the technic can be used with peroxidase-labeled antibody to localize two antigens in the same tissue.
Am J Clin Pathol 1979 May
PMID:Improvement of the glucose oxidase immunoenzyme technic. Use of a tetrazolium whose formazan is stable without heavey metal chelation. 3 46


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