Substrates for the fluorometric determination of oxidative enzymes

Guilbault, George G.; Brignac, Paul J.; Juneau, Mark.

doi:10.1021/ac60264a027

Cited by 395 publications

(159 citation statements)

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“…H 2 O 2 (5 M) was incubated with a catechin or other antioxidant (0.5, 1.0, 1.5 or 2.5 M) in a 37.5 mM sodium acetate buffer (pH 7.4) at room temperature for 10 min. Remaining H 2 O 2 was determined according to the method of Guilbault et al 24) To 0.1 ml of the sample after incubation, 0.2 ml of 0.84 M EDTA in a 0.35 M potassium phosphate buffer at pH 7.0, 0.2 ml of a peroxidase solution (10 units/ml) in the 0.35 M potassium phosphate buffer (pH 7.0) containing 8 mM p-hydroxyphenylacetic acid, and 0.2 ml of 0.4 M NaOH were added, before the mixture was diluted with 3.4 ml of water. The fluorescence of the solution was measured at an excitation of 322 nm and emission of 406 nm.…”

mentioning

confidence: 99%

Prooxidative Activities of Tea Catechins in the Presence of Cu²⁺

Hayakawa

Ishizu

Hoshino

et al. 2004

Bioscience, Biotechnology, and Biochemistry

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mentioning

confidence: 99%

Prooxidative Activities of Tea Catechins in the Presence of Cu²⁺

Hayakawa

Ishizu

Hoshino

et al. 2004

Bioscience, Biotechnology, and Biochemistry

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“…18,19 In analogy with 3-(p-hydroxyphenyl)propionic acid and homovanillic acid, KA may be oxidized with H2O2 and condensed to produce a fluorescent dimer, although the structure of the reaction product in this study is still not clear. Because HRP is not always so specific in its choice of substrates, KA may participate as a mono-proton donor in reaction (1) to be oxidized into a fluorescent dimer.…”

Section: Fluorescent Derivatization Of Ka With Hrpmentioning

confidence: 89%

Spectrofluorometric Determination of Kynurenic Acid with Horseradish Peroxidase in the Presence of Hydrogen Peroxide

2007

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The catalytic activity of horseradish peroxidase (HRP) in the presence of hydrogen peroxide has been investigated for the fluorescent derivatization of kynurenic acid under conditions with no exposure to light. Non-fluorescent kynurenic acid was converted into a fluorescent compound (Ex: 367 nm, Em: 470 nm) with HRP in the presence of hydrogen peroxide, and the optimum conditions of this fluorescent derivatization were investigated. Moreover, this fluorescent derivatization was developed for a spectrofluorometric determination of trace amounts of kynurenic acid by measuring the fluorescence intensity of the fluorescent compound. The calibration curve obtained was linear from 1.0 to 10.0 nmol of kynurenic acid in a 1.0 mL sample solution. The relative standard deviation at 5.0 nmol of kynurenic acid was 5.71% (n = 5). By adjusting the bandwidths for both the excitation and emission to 15 nm, the calibration curve was also linear in the range between 0.1 to 1.0 nmol of kynurenic acid in a 1.0 mL sample solution. This method was applied to the fluorometric determination of trace amounts of kynurenic acid in the control sera.

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“…To 10 ml THE solution of 5,5'-diamino-2,2'-dimethoxybiphenyl (100 mg, 0.409 mmol), acetic anhydride (116 µl, 1.13 mmol) and triethylamine (112 p1, 0.82 mmol) were added; the solution was stirred at ambient temperature for 1 h. The resulting white precipitate was collected and washed with THE to afford 125 mg (93%) of 5,5'-diacetamido-2,2'-dimethoxybiphenyl as a white powder. In a fluorescent assay study using p-acetamidophenol analogs (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20), it was found that contamination from the parent p-aminophenols caused undesirable effects, such as inducing a time lag in the enzymatic reacton with HRP at low HRP activity and an instability from the stock solutions ofp-acetamidophenols.…”

Section: (M 4h Aromatic H) 720 -740 (M 4h Aromatic H) 22'-dimentioning

confidence: 99%