Mechanism of action of 4-dialkylaminopyridines as secondary enhancers in enhanced chemiluminescence reaction (original) (raw)
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Journal of Photochemistry and Photobiology A: Chemistry, 1995
The chemiluminescent emission from the luminoI-HaOa-horseradish peroxidase system was enhanced between 2 and 80 times, during the first 5 min, by chemical indicators, such as phenolphthalein, cresolphthalein, phenol red, cresol red, benzidine and o-tolidine. Phenol derivatives showed emission maxima at pH 8.5, while aniline derivatives showed emission maxima at pH 10.5. The enhancers with a methyl group at the ortho or para position to the OH and NH2 groups in the benzene ring showed an inhibitory effect when their concentrations were increased.
Haloperoxidase-Catalyzed Luminol Luminescence
Antioxidants
Common peroxidase action and haloperoxidase action are quantifiable as light emission from dioxygenation of luminol (5-amino-2,3-dihydrophthalazine-1,4-dione). The velocity of enzyme action is dependent on the concentration of reactants. Thus, the reaction order of each participant reactant in luminol luminescence was determined. Horseradish peroxidase (HRP)-catalyzed luminol luminescence is first order for hydrogen peroxide (H2O2), but myeloperoxidase (MPO) and eosinophil peroxidase (EPO) are second order for H2O2. For MPO, reaction is first order for chloride (Cl−) or bromide (Br−). For EPO, reaction is first order for Br−. HRP action has no halide requirement. For MPO and EPO, reaction is first order for luminol, but for HRP, reaction is greater than first order for luminol. Haloperoxidase-catalyzed luminol luminescence requires acidity, but HRP action requires alkalinity. Unlike the radical mechanism of common peroxidase, haloperoxidases (XPO) catalyze non-radical oxidation of h...
Enhancement of luminol chemiluminescence by cysteine and glutathione
The Analyst, 2000
Cysteine enhancement of cobalt(II)-catalysed chemiluminescence of hydrogen peroxide and luminol occurs in carbonate buffer (but not in borate buffer), whether cysteine mixes with hydrogen peroxide before it mixes with luminol-cobalt(II) or vice versa. Enhancement was measured by the ratio of the signals in the presence and absence of cysteine; standard errors were generally < 5% of the mean ratio. Cystine in sufficiently acidic solution also enhances the chemiluminescence but otherwise diminishes the emission. The emission is also inhibited by glutathione. A mixed solution of cysteine and cystine gives rise to enhanced signals. In all the above cases, enhancement occurs only in the presence of a cobalt(II) catalyst. Luminol-peroxynitrite chemiluminescence is enhanced by cysteine and by glutathione without the presence of a catalyst.
Photochemistry and Photobiology, 1979
The influence of pH and concentration of reagents on the chemiluminescence emitted during peroxidase mediated oxidation of phenol derivatives was studied. Maximal light emission was determined under conditions where chemiluminescence due to auto-oxidation was negligible. With phloroglucinol and purpurogallin as substrates, a direct proportionality was obtained between the concentration of peroxidase and the maximal light emission. p-Phenylenediamine enhances &fold the light emitted with purpurogallin. With resorcinol as substrate the relation between concentration of enzyme and maximal light emission gives an S-shaped curve. With pyrogallol the light emitted is proportional to the square of the concentration of peroxidase.
Journal of Photochemistry and Photobiology A: Chemistry, 1997
The enhancement or inhibition produced by 4-hydroxyazobenzene, 4'-hydroxyazobenzene-2-carboxylic acid (HABA), 7-hydroxycoumatin, 7-hydroxy-4-methylcoumarin, 7-hydroxycoumarin-4-acetic acid, 4-hydroxypyfidine, 6-hydroxyquinoline, vanillin, p-rosolic acid, phenylacetate, 4-phenylphenolacetate, 5-aminoquinoline and 5-aminoisoquinoline on the luminol-H2Ot-horseradish peroxidase chemiluminescence were studied. These phenomena were compared with the effects produced by some enhancers ~,own with similar structures to the previous eompound~, such as, phenol, 4-phenyiphenol, 4-hydroxycinnamic acid, 2-naphthoi, 4-hydroxybenzaldehyde, phenolphthalein and l-aminonaphthalene. The enhancer activity was related to particular structures of each compound, reaction rate constants with horseradish peroxidase, pH and enhancer concentration.
Talanta, 2007
In the present study, three luminol signal enhancers {4-methoxyphenol, 4-hydroxybiphenyl and 4-(1H-pyrrol-1-yl)phenol} were utilized in the chemiluminescence (CL) substrate solution of horseradish peroxidase (HRP). The latter was applied in a heterogenous enzyme immunoassay that has been previously described. The employment of these molecules greatly affected important assay parameters, such as detection limit and the range of the calibration curve and the results were compared with those obtained from other two similar enhancers that have been described from our group. Practically, the use of a novel enhancer, even if this is a slightly changed 4-substituted phenol derivative, can affect assay properties so dramatically, one can assume that another substrate/enzyme system was applied. Furthermore, the use of different luminol signal enhancers in the luminol/HRP/H 2 O 2 system affected not only the intensity of the obtained signal, which is well known, but also its kinetics. It was monitored that the stronger intensity was combined with a more rapid decrease of the CL signal.
Analytical Biochemistry, 2009
a b s t r a c t 3-(10 0 -Phenothiazinyl)propane-1-sulfonate (SPTZ) was shown to be a potent enhancer of soybean peroxidase (SbP)-induced chemiluminescence. To the best of our knowledge, SPTZ is the first enhancer of SbP to be discovered. Optimal conditions for SbP-catalyzed oxidation of luminol in the presence of SPTZ were determined. The SbP-SPTZ system showed better sensitivity and a lower detection limit (LDL) with respect to the horseradish peroxidase-4-iodophenol system traditionally used in chemiluminescent enzyme-linked immunosorbent assay (ELISA). The addition of 4-morpholinopyridine (MORP) to the SbP-SPTZ system improved its analytical parameters by decreasing the LDL of SbP to 0.03 pM. These results open up very promising perspectives for using the SbP-SPTZ-MORP system in ultrasensitive immunoassay.
Talanta, 2012
Using a full factorial design the optimization of experimental conditions of enhanced chemiluminescence reaction (ECR) catalyzed by horseradish peroxidase (HRP-C) in the presence of 3-(10 -phenothiazinyl)propane-1-sulfonate (SPTZ) and 4-morpholinopyridine (MORP) as enhancers was performed. The effect of concentrations of SPTZ, hydrogen peroxide, MORP, luminol, and Tris on a ratio of peroxidase-catalyzed CL to background was studied. The use of the full 2 5 factorial design instead of "one-variable-a time" method allowed to increase the sensitivity of HRP-C determination 2355 fold without a change of detection limit. The obtained results open up very promising perspectives for using HRP-C-catalyzed ECR to improve the sensitivity of chemiluminescent enzyme immunoassay.