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Clark KB, Bhattacharyya K, Das PK, Scaiano JC, Schaap AP. Photochemistry of 2,3-di(1'-naphthyl)oxiranes. Spectral and kinetic behavior of carbonyl ylides in condensed media. J Org Chem 2002. [DOI: 10.1021/jo00039a036] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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2
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Carlson EH, Schaap AP, Raban M. Stereochemistry in trivalent nitrogen compounds. XVIII. Slow rotation about the nitrogen-to-carbonyl bonds in N,N'-biscarboethoxy-3,3,4,4-tetramethoxy-1,2-diazetidene. J Org Chem 2002. [DOI: 10.1021/jo00948a034] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Akhavan-Tafti H, DeSilva R, Sugioka K, Handley RS, Schaap AP. Chemiluminescent acridan phosphate labelling compounds for detection in gels. LUMINESCENCE 2001; 16:187-91. [PMID: 11312546 DOI: 10.1002/bio.652] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We have developed a chemiluminescent acridan phosphate labelling compound which produces a flash of light upon chemical triggering. Sequential treatment of the label with acid and a strong base, one of which contains a peroxide, initiates light emission as a rapid flash lasting 1--2 s. Labelling of analytes with these compounds permits their direct detection in a non-enzymatic assay format. Representative compounds have been linked to BSA as a model protein analyte and detected by chemiluminescence assay. Light intensity correlated with the amount of BSA over six orders of magnitude, permitting the detection of 50 amol of protein in solution. We have also demonstrated for the first time that labelled proteins can be separated by electrophoresis without destruction of the label and that chemiluminescence can be produced and detected directly in the gel. The ease, speed and sensitivity of detection by this new method should enable the development of simpler assays for a wide variety of analytes.
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Affiliation(s)
- H Akhavan-Tafti
- Lumigen Inc., 24485 W. Ten Mile Rd., Southfield, MI 48034, USA
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Abstract
Electrochemical oxidation of the acridan 2',6'-difluorophenyl 10-methylacridan-9-carboxylate produces the corresponding acridinium ester, which reacts with hydrogen peroxide forming a dioxetanone intermediate. Decomposition of the dioxetanone generates light at 430 nm when it relaxes to the ground state. The effect of pH and hydrogen peroxide concentration on this ECL reaction and on the stability of the acridan were investigated. At pH 8.0 and a hydrogen peroxide concentration of 10 mM, light emission from the ECL reaction was used to determine the acridan concentration with a detection limit of 54 pmol L(-1). Results suggest that acridan esters could be used as labels in ECL immunoassays and nucleotide assays.
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Affiliation(s)
- R Wilson
- Department of Chemistry, Liverpool University, UK
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Reddy LV, DeSilva R, Handley RS, Schaap AP, Akhavan-Tafti H. Sequential chemiluminescent detection of target DNAs without stripping and reprobing. Biotechniques 1999; 26:710-4. [PMID: 10343910 DOI: 10.2144/99264st08] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
We present a simple method for sequential chemiluminescent detections of two different DNA loci on a single Southern blot. First, an enzyme-linked DNA probe for a unique sequence is detected with a horse-radish peroxidase (HRP) substrate followed by the detection of another enzyme-linked DNA probe for a different unique sequence with an alkaline phosphatase (AP) substrate that simultaneously inhibits the chemiluminescence generated by HRP. Such sequential detection steps eliminate the need to strip and reprobe blots and can be performed with no intervening steps.
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Affiliation(s)
- L V Reddy
- Lumigen, Inc., Southfield, MI 48034, USA
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Akhavan-Tafti H, Reddy LV, Siripurapu S, Schoenfelner BA, Handley RS, Schaap AP. Chemiluminescent detection of DNA in low- and medium-density arrays. Clin Chem 1998; 44:2065-6. [PMID: 9733015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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7
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Akhavan-Tafti H, Schaap AP, Arghavani Z, DeSilva R, Eickholt RA, Handley RS, Schoenfelner BA, Sugioka K, Sugioka Y. CCD camera imaging for the chemiluminescent detection of enzymes using new ultrasensitive reagents. J Biolumin Chemilumin 1994; 9:155-64. [PMID: 7942120 DOI: 10.1002/bio.1170090309] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We have designed and constructed an inexpensive imaging system based on charge-coupled device (CCD) technology and utilized it to demonstrate the sensitivity and rapid detection possible with Lumigen chemiluminescent reagents. We also report the development of two new chemiluminescent reagents, Lumi-Phos Plus and Lumigen PS. Lumi-Phos Plus is an enhanced formulation for the rapid detection of alkaline phosphatase on membranes and in solution. It provides excellent images in blotting applications with exposures of under a minute. Lumigen PS represents a new generation of peroxidase detection reagents. The wide dynamic range with excellent linearity, higher signal and lower background than other chemiluminescent reagents make Lumigen PS of unsurpassed value in enzyme-linked immunoassays and nucleic acid probe assays using HRP conjugates.
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Beale EG, Deeb EA, Handley RS, Akhavan-Tafti H, Schaap AP. A rapid and simple chemiluminescent assay for Escherichia coli beta-galactosidase. Biotechniques 1992; 12:320-3. [PMID: 1571136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
We describe a chemiluminescent assay for E. coli beta-galactosidase using Lumi-Gal 530, a commercial formulation containing a stable phenylgalactose-substituted dioxetane as the substrate. Removal of the galactose moiety leads to the generation of an unstable dioxetane which decomposes to provide the observed chemiluminescence which is measured with a luminometer. Advantages of the assay are that it is simple, inexpensive and has 20-fold greater sensitivity than the standard spectrophotometric assay. Additional advantages are that the dioxetane is quite stable in the commercial formulation, and beta-galactosidase functions efficiently and is not degraded during the course of an assay. As luminometers are becoming commonplace in molecular biology laboratories, this assay provides a preferable alternative to the spectrophotometric assay.
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Affiliation(s)
- E G Beale
- Department of Cell Biology and Anatomy, Texas Tech University Health Sciences Center Lubbock 79430
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Pollard-Knight D, Simmonds AC, Schaap AP, Akhavan H, Brady MA. Nonradioactive DNA detection on Southern blots by enzymatically triggered chemiluminescence. Anal Biochem 1990; 185:353-8. [PMID: 2140249 DOI: 10.1016/0003-2697(90)90307-u] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A chemiluminescent reaction based on the deprotection of a phosphorylated phenyl dioxetane by alkaline phosphatase has recently been described (Schaap, A.P., 1988, J. Biolumin. Chemilumin. 2, 253). Light output is enhanced by intermolecular energy transfer to a micelle-solubilized fluorophore. This system is applied here to the detection of DNA probes on Southern blots. Enzyme solution assays which give an indication of sensitivity show that using this substrate 100 fg (0.7 amol) alkaline phosphatase can be detected on a luminescence plate reader (200 ms reading time). In a model Southern blotting system 180 fg HindIII digested lambda DNA was detected on film with homologous biotinylated DNA and a streptavidin-alkaline phosphatase complex. The single copy genes mos and raf-1, representing targets of 4.2 and 2.4 pg target DNA respectively, have also been detected in Southern-blotted human genomic DNA. A delay in reaching a plateau level of light output which is dependent on pH is observed but signal continues for at least 7 days. Typically, 12-h exposures to X-ray film were performed but once a steady-state light output had been achieved this time could be reduced to 2 h by preflashing film. This detection system represents a sensitive nonradioactive method, which is applicable not only to Southern blots but also to Northern and Western blots and any assay in which alkaline phosphatase is the label.
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Affiliation(s)
- D Pollard-Knight
- Corporate Research, Amersham International plc, Pollards Wood Laboratories, Bucks, United Kingdom
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Schaap AP, Akhavan H, Romano LJ. Chemiluminescent substrates for alkaline phosphatase: application to ultrasensitive enzyme-linked immunoassays and DNA probes. Clin Chem 1989; 35:1863-4. [PMID: 2505948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- A P Schaap
- Dept. of Chem., Wayne State Univ., Detroit, MI 48202
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Schaap AP, Akhavan H, Romano LJ. Chemiluminescent substrates for alkaline phosphatase: application to ultrasensitive enzyme-linked immunoassays and DNA probes. Clin Chem 1989. [DOI: 10.1093/clinchem/35.9.1863] [Citation(s) in RCA: 162] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- A P Schaap
- Dept. of Chem., Wayne State Univ., Detroit, MI 48202
| | - H Akhavan
- Dept. of Chem., Wayne State Univ., Detroit, MI 48202
| | - L J Romano
- Dept. of Chem., Wayne State Univ., Detroit, MI 48202
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Clyne JM, Running JA, Stempien M, Stephens RS, Akhavan-Tafti H, Schaap AP, Urdea MS. A rapid chemiluminescent DNA hybridization assay for the detection of Chlamydia trachomatis. J Biolumin Chemilumin 1989; 4:357-66. [PMID: 2508437 DOI: 10.1002/bio.1170040149] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
With an estimated 3-4 million new cases per year, human infections from Chlamydia trachomatis are probably the most prevalent sexually transmitted disease (STD) in the United States. Diagnosis of Chlamydia is usually conducted by tissue culture methods. Direct immunofluorescence and ELISA tests have become available, but there remains a need for a test with better specificity and sensitivity. In response to this need, we have developed a rapid DNA hybridization assay using synthetic oligonucleotide probes to detect the presence of the Chlamydia trachomatis specific 7.4 kb plasmid. The assay involves solution phase hybridization of unlabelled probes, rapid capture of the probe-target duplex onto a microtitre dish surface, a new signal amplification technique that employs chemically cross-linked oligonucleotides, and an alkaline phosphatase labelled probe. Signal is obtained by reacting the labelled probe-target complex with an enzyme triggerable dioxetane substrate. Detection of the chemiluminescent output is performed either with a luminometer or by exposure to instant film. All 15 serovars of Chlamydia trachomatis react positively, while organisms known to co-inhabit the human urogenital tract react negatively.
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Affiliation(s)
- J M Clyne
- University of California San Francisco, Department of Laboratory Medicine 94143
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Abstract
We reported evidence that horseradish peroxidase (HRP) and chloroperoxidase (CPO) catalyze oxygen transfer from H2O2 to thioanisoles [Kobayashi, S., Nakano, M., Goto, T., Kimura, T., & Schaap, A. P. (1986) Biochem. Biophys. Res. Commun. 135, 166-171]. In the present paper, the reaction mechanism of this oxygen transfer is discussed. The oxidation of para-substituted thioanisoles by HRP compound II showed a large negative rho value of -1.46 vs. the sigma + parameter in a Hammett plot. These results are in accord with the formation of a cation radical intermediate in the rate-determining step. Hammett treatments for HRP- and CPO-dependent S-oxygenations did not provide unequivocal proofs to judge the reaction mechanism, because of the poor correlations for sigma + and sigma p parameters. Different behavior was found in kinetics and stereoselectivity between the two enzymes. Results in the present study and recent studies strongly suggested the formation of a cation radical intermediate. The oxygen atom would transfer by reaction of compound II and the cation radical intermediate. Although involvement of the cation radical was not confirmed in the CPO system, a similar mechanism was proposed for CPO.
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Affiliation(s)
- S Kobayashi
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202
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Kobayashi S, Nakano M, Goto T, Kimura T, Schaap AP. An evidence of the peroxidase-dependent oxygen transfer from hydrogen peroxide to sulfides. Biochem Biophys Res Commun 1986; 135:166-71. [PMID: 3954766 DOI: 10.1016/0006-291x(86)90957-5] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Horseradish- and chloro-peroxidase catalyzed oxidation of sulfides have been investigated. Thioanisoles were oxygenated to the corresponding sulfoxides by such peroxidases at the expense of H2O2. Dealkylation was observed only in the chloroperoxidase-dependent oxidations of p-methoxy- and p-iso-propoxy-thioanisoles. The experiments with 18O-labeled H2O2 indicated that an oxygen atom of H2O2 is incorporated into the sulfoxides. These research lead to the conclusion that compound I or II is capable of acting as an oxygen donor as well as an electron acceptor.
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Klimek J, Schaap AP, Kimura T. Effect of paraquat on cytochrome P-450-dependent lipid peroxidation in bovine adrenal cortex mitochondria. Biochim Biophys Acta 1983; 752:127-36. [PMID: 6849960 DOI: 10.1016/0005-2760(83)90240-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
We have investigated the effect of paraquat (methyl viologen) on lipid peroxidation in bovine adrenal cortex mitochondria. Incubation of a buffered aerobic mixture of mitochondria in the presence of Fe2+ or NADPH resulted in the formation of lipid peroxides whose accumulation could be followed at 532 nm as malondialdehyde. Fe2+ stimulates lipid peroxidation in normal mitochondria and those in which enzymes have been inactivated with heat. In contrast, NADPH has a stimulatory effect only in normal mitochondria, but not in heat-treated mitochondria. These results indicate that NADPH-dependent lipid peroxidation is an enzymatic process. Paraquat strongly inhibits this enzymatic lipid peroxidation, but has no effect on the non-enzymatic Fe2+-dependent process. The chemiluminescence that accompanies the NADPH-dependent lipid peroxidation is also markedly decreased in the presence of paraquat. Superoxide dismutase, which removes superoxide anion efficiently, does not inhibit malondialdehyde production. The mechanism of the inhibition of the lipid peroxidation by paraquat has been examined. Paraquat has no effect on NADPH-2,6-dichlorophenolindophenol reductase and on NADPH-cytochrome c reductase activities in bovine adrenal cortex mitochondria. However, paraquat strongly inhibits the NADPH-dependent reduction of cytochrome P-450. These results suggest that the inhibitory effect of paraquat on NADPH-dependent lipid peroxidation in adrenal cortex mitochondria is due to a decrease in the level of reduced cytochrome P-450 probably by diverting electrons from cytochrome P-450. Cytochrome c, which can compete with P-450 for available electrons from adrenodoxin, like paraquat had an inhibitory effect on NADPH-dependent lipid peroxidation. Lipid peroxidation was also strongly inhibited by steroid hydroxylase inhibitors, e.g., amphenone B, aminoglutethimide and metyrapone.
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Klimek J, Schaap AP, Kimura T. The relationship between NADPH-dependent lipid peroxidation and degradation of cytochrome P-450 in adrenal cortex mitochondria. Biochem Biophys Res Commun 1983; 110:559-66. [PMID: 6838538 DOI: 10.1016/0006-291x(83)91186-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The relationship between NADPH-dependent lipid peroxidation and the degradation of cytochrome P-450 has been studied in bovine adrenal cortex mitochondria. Malondialdehyde formation is accompanied by a corresponding decrease in total cytochrome P-450 content. Inhibitors of lipid peroxidation also prevent the loss of cytochrome P-450, further demonstrating a direct relationship between NADPH-dependent lipid peroxidation and degradation of P-450. To differentiate between cytochrome P-450(11)beta and P-450scc, steroid-induced difference spectra were used to evaluate P-450 degradation. These measurements provide the first evidence that both P-450's are degraded during NADPH-dependent lipid peroxidation with P-450(11)beta being much more susceptible to this process.
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Klimek J, Schaap AP, Kimura T. Inhibition of lipid peroxidation by paraquat: site of inhibition in the cytochrome P-450-dependent steroid hydroxylase system from bovine adrenal cortex mitochondria. Biochem Biophys Res Commun 1982; 107:499-505. [PMID: 6215039 DOI: 10.1016/0006-291x(82)91519-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Suwa K, Kimura T, Schaap AP. Reactivity of singlet molecular oxygen with cholesterol in a phospholipid membrane matrix. A model for oxidative damage of membranes. Biochem Biophys Res Commun 1977; 75:785-92. [PMID: 577147 DOI: 10.1016/0006-291x(77)91541-8] [Citation(s) in RCA: 96] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Goda K, Kimura T, Thayer AL, Kees K, Schaap AP. Singlet molecular oxygen in biological systems: non-quenching of singlet oxygen-mediated chemiluminescence by superoxide dismutase. Biochem Biophys Res Commun 1974; 58:660-6. [PMID: 4836270 DOI: 10.1016/s0006-291x(74)80469-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Goda K, Chu J, Kimura T, Schaap AP. Cytochrome c enhancement of singlet molecular oxygen production by the NADPH-dependent adrenodoxin reductase-adrenodoxin system: the role of singlet oxygen in damaging adrenal mitochondrial membranes. Biochem Biophys Res Commun 1973; 52:1300-6. [PMID: 4146221 DOI: 10.1016/0006-291x(73)90642-6] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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