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Biochemistry May 1979Changes in the optical absorption spectrum of horseradish peroxidase, during the oxidation of o-dianisidine at pH 7.5, reveal an intermediate distinct from the...
Chemical and enzymatic intermediates in the peroxidation of o-dianisidine by horseradish peroxidase. 2. Evidence for a substrate radical--enzyme complex and its reaction with nucleophiles.
Changes in the optical absorption spectrum of horseradish peroxidase, during the oxidation of o-dianisidine at pH 7.5, reveal an intermediate distinct from the previously described compounds I and II. The rate of decay of this new complex appeared to be rate limiting for the catalytic cycle, in this pH range, since imidazole, which augments the catalytic reaction, also enhanced the rate of decay of this complex. Nitrogenous compounds reportedly unable to ligate to hemes, such as 2-methylimidazole and benzimidazole, were nevertheless capable of augmenting the HRP-catalyzed rate of oxidation of o-dianisidine. The activity of nitrogenous compounds, in this regard, appeared to be a function of their nucleophilicity and was sensitive to steric factors but relatively free of a deuterium solvent isotope effect. The data presented in this and in the preceding paper [Claiborne, A., & Fridovich, I. (1979) Biochemistry 18 (preceding paper in this issue)] lead to the suggestion that the nucleophile-responsive intermediate is an enzyme--dianisidine radical complex and that abstraction of the second electron from the bound radical is facilitated by binding of nitrogenous nucleophiles.
Topics: Benzidines; Dianisidine; Free Radicals; Horseradish Peroxidase; Hydrogen Peroxide; Imidazoles; Kinetics; Peroxidases; Peroxides; Protein Binding; Pyridines; Spectrophotometry
PubMed: 444459
DOI: 10.1021/bi00578a030 -
Biochemistry May 1979
Topics: Benzidines; Binding Sites; Dianisidine; Electron Spin Resonance Spectroscopy; Horseradish Peroxidase; Kinetics; Oxidation-Reduction; Peroxidases; Peroxides; Protein Binding; Spectrophotometry
PubMed: 221005
DOI: 10.1021/bi00578a029 -
Clinical Biochemistry Apr 19761. Due to the carcinogenicity of benzidine, a method by which o-dianisidine is used to stain serum haptoglobin is described. Serum haptoglobin is determined by... (Comparative Study)
Comparative Study
1. Due to the carcinogenicity of benzidine, a method by which o-dianisidine is used to stain serum haptoglobin is described. Serum haptoglobin is determined by electrophoresis using cellulose acetate as the medium. 2. A comparison of the two staining systems demonstrates good agreement. 0-Dianisidine can be substituted for benzidine without loss of specificity.
Topics: Dianisidine; Electrophoresis, Cellulose Acetate; Haptoglobins; Humans; Indicators and Reagents
PubMed: 1260999
DOI: 10.1016/s0009-9120(76)80028-8 -
Immunochemistry Jan 1969
Topics: Aldehydes; Aniline Compounds; Animals; Antigen-Antibody Reactions; Antigens; Azo Compounds; Diazonium Compounds; Erythrocytes; Freeze Drying; Hemagglutination Tests; Humans; Rabbits; Sheep; Tannins; Triazines
PubMed: 5773762
DOI: 10.1016/0019-2791(69)90179-7 -
Toxicologic Pathology 2005Cardiac thrombosis, one of the causes of sudden death throughout the world, plays a principal role in several cardiovascular diseases, such as myocardial infarction and... (Comparative Study)
Comparative Study Review
Cardiac thrombosis, one of the causes of sudden death throughout the world, plays a principal role in several cardiovascular diseases, such as myocardial infarction and stroke in humans. Data from studies of induction of chemical thrombosis in rodents help to identify substances in our environment that may contribute to cardiac thrombosis. Results for more than 500 chemicals tested in rodents in 2-year bioassays have been published as Technical Reports of the National Toxicology Program (NTP) http://ntp-server.niehs.nih.gov/index. We evaluated atrial thrombosis induced by these chemical exposures and compared it to similarly induced lesions reported in the literature. Spontaneous rates of cardiac thrombosis were determined for control Fischer 344 rats and B6C3F1 mice: 0% in rats and mice in 90-day studies and, in 2-year studies, 0.7% in both genders of mice, 4% in male rats, and 1% in female rats. Incidences of atrial thrombosis were increased in high-dosed groups involving 13 compounds (incidence rate: 20-100%): 2-butoxyethanol, C.I. Direct Blue 15, bis(2-chloroethoxy)methane, diazoaminobenzene, diethanolamine, 3,3'-dimethoxybenzidine dihydrochloride, hexachloroethane, isobutene, methyleugenol, oxazepam, C.I. Pigment Red 23, C.I. Acid Red 114, and 4,4'-thiobis(6-t-butyl-m-cresol). The main localization of spontaneously occurring and chemically induced thromboses occurred in the left atrium. The literature survey suggested that chemical-induced atrial thrombosis might be closely related to myocardial injury, endothelial injury, circulatory stasis, hypercoagulability, and impaired atrial mechanical activity, such as atrial fibrillation, which could cause stasis of blood within the left atrial appendage, contributing to left atrial thrombosis. Supplementary data referenced in this paper are not printed in this issue of Toxicologic Pathology. They are available as downloadable files at http://taylorandfrancis.metapress.com/openurl.asp?genre=journal&issn=0192-6233. To access them, click on the issue link for 33(5), then select this article. A download option appears at the bottom of this abstract. In order to access the full article online, you must either have an individual subscription or a member subscription accessed through www.toxpath.org.
Topics: Alkenes; Anilides; Animals; Azo Compounds; Coronary Thrombosis; Cresols; Dianisidine; Dose-Response Relationship, Drug; Ethane; Ethanolamines; Ethyl Ethers; Ethylene Glycols; Eugenol; Female; Heart Atria; Hydrocarbons, Chlorinated; Male; Mice; Mice, Inbred Strains; Naphthalenesulfonates; Oxazepam; Rats; Rats, Inbred F344; Toxicity Tests, Chronic; Triazenes
PubMed: 16048847
DOI: 10.1080/01926230591034429 -
Methods in Molecular Medicine 2005The zebrafish (Danio rerio) has emerged as a powerful vertebrate genetic and developmental model that is particularly amenable to the study of hematopoiesis. The... (Review)
Review
The zebrafish (Danio rerio) has emerged as a powerful vertebrate genetic and developmental model that is particularly amenable to the study of hematopoiesis. The zebrafish embryo develops externally and its optical clarity allows the number and morphology of circulating blood cells to be visualized using a dissecting microscope. Both the morphology of the blood lineages and the expression of critical blood genes are highly conserved between zebrafish and mammals. The high fecundity and short generation time of zebrafish facilitate genetic analysis, and a number of large-scale mutagenesis screens have identified mutations in genes affecting blood development. The discovery of novel hematopoietic genes, as well as the cloning of zebrafish homologs of known hematopoietic genes, necessitates the use of efficacious and reliable methods for complete gene characterization. In this chapter, we illustrate frequently used techniques that are essential for evaluating hematopoiesis in the zebrafish, including whole-mount in situ hybridization, the detection of erythrocytes by o-dianisidine staining, and a description of the microinjection procedure, which has various applications, including overexpression of messenger ribonucleic acid, gene "knockdown" by antisense technology, and the creation of transgenic zebrafish. Also included is an explanation of the use of flow cytometry to separate hematopoietic lineages from the adult kidney and to isolate relatively pure populations of cell types from transgenic embryos based on the expression of fluorescent markers.
Topics: Animals; Animals, Genetically Modified; Cell Lineage; Gene Expression Regulation, Developmental; Gene Transfer Techniques; Hematopoiesis; Mutagenesis; Zebrafish
PubMed: 15492396
DOI: 10.1385/1-59259-826-9:171 -
Comparison of the catalytic oxidation of cysteine and o-dianisidine by cupric ion and ceruloplasmin.Journal of Inorganic Biochemistry Aug 1982Several features of the catalytic oxidation of cysteine by ceruloplasmin and nonenzymic Cu(II) at pH 7 have been compared. The oxidation of cysteine by ceruloplasmin has... (Comparative Study)
Comparative Study
Several features of the catalytic oxidation of cysteine by ceruloplasmin and nonenzymic Cu(II) at pH 7 have been compared. The oxidation of cysteine by ceruloplasmin has several properties in common with the Cu(II) catalyzed oxidation of cysteine: pH maxima, thiol specificity, lack of inhibition by anions, and high sensitivity to inhibition by copper complexing reagents. These two catalysts differed in their molecular activity, in their ability to oxidize penicillamine and thioglycolate, and in that H2O2 was produced as a primary product only during Cu(II) oxidation. The oxidation of cysteine by ceruloplasmin was compared also with the ceruloplasmin catalyzed oxidation of o-dianisidine, a classical pH 5.5 substrate. The mechanism of the oxidation of cysteine by ceruloplasmin at pH 7 differed from that of o-dianisidine oxidation because the latter substrate was inhibited by anions but not by copper complexing agents. Spectral and other data suggest that during the ceruloplasmin reaction with cysteine there is a one electron transfer from cysteine to ceruloplasmin resulting in the specific reduction of type 1b Cu(II).
Topics: Animals; Benzidines; Ceruloplasmin; Chelating Agents; Copper; Cysteine; Dianisidine; Hydrogen-Ion Concentration; Kinetics; Oxidation-Reduction; Substrate Specificity
PubMed: 7119774
DOI: 10.1016/s0162-0134(00)80229-9 -
Biomedica Biochimica Acta 1990A simple, rapid and inexpensive method (o-DD method) is described for the measurement of hydrogen peroxide released by human polymorphonuclear leukocytes (PMNL)...
Hydrogen peroxide release from human polymorphonuclear leukocytes measured with horseradish peroxidase and o-dianisidine. Effect of various stimulators and cytochalasin B.
A simple, rapid and inexpensive method (o-DD method) is described for the measurement of hydrogen peroxide released by human polymorphonuclear leukocytes (PMNL) stimulated with phorbol myristate acetate (PMA), n-formyl-methionyl-leucyl-phenylalanine (FMLP) and concanavalin A (Con A). The method is based on the horseradish peroxidase-catalysed oxidation of o-dianisidine by H2O2 which results in the formation of a compound exhibiting an increased absorbance at 470 nm. A linear relationship between the absorbance at 470 nm and the concentration of H2O2 was found in the 1-150 microM range. Using this assay the time course of H2O2 release by PMNL, the dependence of H2O2 release on cell number, the agonist concentration and the presence of cytochalasin B (4.8 micrograms/ml) were studied. The maximal PMNL H2O2 response was found for PMA at 10 ng/ml. Con A at 200 micrograms/ml, FMLP at 300 ng/ml and reached 39 +/- 1.5, 14 +/- 1.2, 2.2 +/- 0.7 nmol for 10(6) cells incubated for 60 min at 37 degrees C. respectively. FMLP under these conditions was a most potent stimulator of myeloperoxidase release (MPO). Cytochalasin B having a weak influence on FMLP- and Con A-mediated H2O2 production enhanced strongly their stimulatory effect on MPO release. It is suggested that measurement of the H2O2 release with the o-DD method could be useful for monitoring PMNL respiratory burst especially in the cases of low MPO release.
Topics: Concanavalin A; Cytochalasin B; Dianisidine; Horseradish Peroxidase; Humans; Hydrogen Peroxide; N-Formylmethionine Leucyl-Phenylalanine; Neutrophils; Peroxidase; Tetradecanoylphorbol Acetate
PubMed: 2176783
DOI: No ID Found -
Talanta Dec 2005A gas diffusion sequential injection system for spectrophotometric determination of free chlorine is described. The detection is based in the colorimetric reaction...
A gas diffusion sequential injection system for spectrophotometric determination of free chlorine is described. The detection is based in the colorimetric reaction between free chlorine and a low toxicity reagent o-dianisidine. A gas diffusion unit is used to isolate free chlorine from the sample in order to avoid possible interferences. This feature results from the conversion of free chlorine to molecular chlorine (gaseous) with sample acidification. With minor changes in the operating conditions, two different dynamic ranges were obtained enhancing the application both to water samples and bleaches. The results obtained with the developed system were compared to the reference method, iodometric titration and proved not to be statistically different. A detection limit of 0.6mg ClO(-)/L was achieved. Repeatability was evaluated from 10 consecutive determinations being the results better than 2%. The two dynamic ranges presented different determination rates: 15h(-1) for 0.6-4.8mg ClO(-)/L (water samples) and 30h(-1) for 0.047-0.188g ClO(-)/L (bleaches).
PubMed: 18970316
DOI: 10.1016/j.talanta.2005.07.028 -
Talanta Feb 2000Reaction of oxidation of o-dianisidine (o-D) with H(2)O(2) which is widely used in catalytic methods of analysis in solution has been conducted on silica plates for...
Reaction of oxidation of o-dianisidine (o-D) with H(2)O(2) which is widely used in catalytic methods of analysis in solution has been conducted on silica plates for thin-layer chromatography. The rate of the reaction catalyzed by model compounds (p-toluenesulphonyl chloride, methyl benzoate, benzoic acid, and acrylamide) is noticeably higher on silica than in solution in comparable conditions. The degree of acceleration varies depending on the catalyst and is more pronounced at its lower concentrations. By use of p-toluenesulphonyl chloride determination as an example it has been shown that the accelerating effect of silica enables to decrease the detection limit down to 0.07 nmol cm(-2) (as compared with 4 nmol.cm(-2) in solution); the accuracy is not diminished. It is concluded that catalytic indicator reactions on solid supports may represent high interest for analytical chemists.
PubMed: 18967871
DOI: 10.1016/s0039-9140(99)00302-1