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Article ; Online: Organic Chemical Contaminants in Water System Infrastructure Following Wildfire.

Draper, William M / Li, Na / Solomon, Gina M / Heaney, Yvonne C / Crenshaw, Reese B / Hinrichs, Richard L / Chandrasena, R Esala P

ACS ES&T water

2022 Volume 2, Issue 2, Page(s) 357–366

Abstract: Wildfires have destroyed multiple residential communities in California in recent years. After fires in 2017 and 2018, high concentrations of benzene and other volatile organic compounds (VOCs) were found in public drinking water systems in fire-affected ...

Abstract	Wildfires have destroyed multiple residential communities in California in recent years. After fires in 2017 and 2018, high concentrations of benzene and other volatile organic compounds (VOCs) were found in public drinking water systems in fire-affected areas. The sources of the contamination and appropriate remediation have been urgent matters for investigation. This study characterizes target and non-target VOCs and semi volatile organic compounds (SVOCs) in water from a highly contaminated service line after the 2018 Camp Fire (Paradise, CA). Ninety-five organic compounds were identified or tentatively identified in the service line. Laboratory combustion experiments with drinking water pipes made of polyvinyl chloride (PVC), cross-linked polyethylene (PEX) and high-density polyethylene (HDPE) and a review of the literature were used to evaluate potential sources of the detected chemicals. Among the service line contaminants were thirty-two compounds associated with PVC pyrolysis and twenty-eight organic compounds also associated with the pyrolysis of polyethylene. The service line sample also contained fifty-five compounds associated with uncontrolled burning of biomass and waste materials. The findings support hypotheses that wildfires can contaminate drinking water systems both by thermal damage to plastic pipes and intrusion of smoke. Residual chlorine disinfectant in the water system modifies the contaminant distribution observed.
Language	English
Publishing date	2022-02-01
Publishing country	United States
Document type	Journal Article
ISSN	2690-0637
ISSN (online)	2690-0637
DOI	10.1021/acsestwater.1c00401
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Article: Highly reactive electrophilic oxidants in cytochrome P450 catalysis.

Newcomb, Martin / Chandrasena, R Esala P

Biochemical and biophysical research communications

2005 Volume 338, Issue 1, Page(s) 394–403

Abstract: The cytochrome P450 enzymes effect a wide range of oxidations in nature including difficult hydroxylation reactions of unactivated C-H. Most of the high energy reactions of these catalysts appear to involve highly electrophilic active species. Attempts ... ...

Abstract	The cytochrome P450 enzymes effect a wide range of oxidations in nature including difficult hydroxylation reactions of unactivated C-H. Most of the high energy reactions of these catalysts appear to involve highly electrophilic active species. Attempts to detect the reactive transients in the enzymes have met with limited success, but evidence has accumulated that two distinct electrophilic oxidants are produced in the P450 enzymes. The consensus electrophilic oxidant termed "iron-oxo" is usually thought to be an analogue of Compound I, an iron(IV)-oxo porphyrin radical cation species, but it is possible that a higher energy electronic isomer of Compound I is required to account for the facility of the C-H oxidation reactions. The second electrophilic oxidant of P450 is speculative; circumstantial evidence suggests that this species is iron-complexed hydrogen peroxide, but this oxidant might be a second spin state of iron-oxo. This overview discusses recent studies directed at detection of the electrophilic oxidants in P450 enzymes and the accumulated evidence for two distinct species.
MeSH term(s)	Animals ; Catalysis ; Cytochrome P-450 Enzyme System/chemistry ; Cytochrome P-450 Enzyme System/metabolism ; Humans ; Oxidants/chemistry ; Oxidants/metabolism ; Substrate Specificity
Chemical Substances	Oxidants ; Cytochrome P-450 Enzyme System (9035-51-2)
Language	English
Publishing date	2005-12-09
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Review
ZDB-ID	205723-2
ISSN	0006-291X ; 0006-291X
ISSN (online)	0006-291X
ISSN	0006-291X
DOI	10.1016/j.bbrc.2005.08.208
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Article ; Online: Selective estrogen receptor modulator (SERM) lasofoxifene forms reactive quinones similar to estradiol.

Michalsen, Bradley T / Gherezghiher, Teshome B / Choi, Jaewoo / Chandrasena, R Esala P / Qin, Zhihui / Thatcher, Gregory R J / Bolton, Judy L

Chemical research in toxicology

2012 Volume 25, Issue 7, Page(s) 1472–1483

Abstract: The bioactivation of both endogenous and equine estrogens to electrophilic quinoid metabolites has been postulated as a contributing factor in carcinogenic initiation and/or promotion in hormone sensitive tissues. Bearing structural resemblance to ... ...

Abstract	The bioactivation of both endogenous and equine estrogens to electrophilic quinoid metabolites has been postulated as a contributing factor in carcinogenic initiation and/or promotion in hormone sensitive tissues. Bearing structural resemblance to estrogens, extensive studies have shown that many selective estrogen receptor modulators (SERMs) are subject to similar bioactivation pathways. Lasofoxifene (LAS), a third generation SERM which has completed phase III clinical trials for the prevention and treatment of osteoporosis, is currently approved in the European Union for this indication. Previously, Prakash et al. (Drug Metab. Dispos. (2008) 36, 1218-1226) reported that similar to estradiol, two catechol regioisomers of LAS are formed as primary oxidative metabolites, accounting for roughly half of the total LAS metabolism. However, the potential for further oxidation of these catechols to electrophilic o-quinones has not been reported. In the present study, LAS was synthesized and its oxidative metabolism investigated in vitro under various conditions. Incubation of LAS with tyrosinase, human liver microsomes, or rat liver microsomes in the presence of GSH as a trapping reagent resulted in the formation of two mono-GSH and two di-GSH catechol conjugates which were characterized by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Similar conjugates were also detected in incubations with P450 3A4, P450 2D6, and P450 1B1 supersomes. Interestingly, these conjugates were also detected as major metabolites when compared to competing detoxification pathways such as glucuronidation and methylation. The 7-hydroxylasofoxifene (7-OHLAS) catechol regioisomer was also synthesized and oxidized either chemically or enzymatically to an o-quinone that was shown to form depurinating adducts with DNA. Collectively, these data show that analogous to estrogens, LAS is oxidized to catechols and o-quinones which could potentially contribute to in vivo toxicity for this SERM.
MeSH term(s)	Animals ; Catechols/chemistry ; Catechols/metabolism ; Cattle ; Chromatography, High Pressure Liquid ; Cytochrome P-450 Enzyme System/metabolism ; DNA/chemistry ; Estradiol/chemistry ; Estradiol/metabolism ; Glutathione/metabolism ; Humans ; Microsomes, Liver/metabolism ; Monophenol Monooxygenase/metabolism ; Oxidation-Reduction ; Pyrrolidines/chemistry ; Pyrrolidines/metabolism ; Quinones/chemistry ; Quinones/metabolism ; Rats ; Selective Estrogen Receptor Modulators/chemistry ; Selective Estrogen Receptor Modulators/metabolism ; Stereoisomerism ; Tandem Mass Spectrometry ; Tetrahydronaphthalenes/chemistry ; Tetrahydronaphthalenes/metabolism
Chemical Substances	Catechols ; Pyrrolidines ; Quinones ; Selective Estrogen Receptor Modulators ; Tetrahydronaphthalenes ; Lasofoxifene (337G83N988) ; Estradiol (4TI98Z838E) ; DNA (9007-49-2) ; Cytochrome P-450 Enzyme System (9035-51-2) ; calf thymus DNA (91080-16-9) ; Monophenol Monooxygenase (EC 1.14.18.1) ; Glutathione (GAN16C9B8O) ; catechol (LF3AJ089DQ)
Language	English
Publishing date	2012-06-14
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	639353-6
ISSN	1520-5010 ; 0893-228X
ISSN (online)	1520-5010
ISSN	0893-228X
DOI	10.1021/tx300142h
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Article ; Online: The naphthol selective estrogen receptor modulator (SERM), LY2066948, is oxidized to an o-quinone analogous to the naphthol equine estrogen, equilenin.

Gherezghiher, Teshome B / Michalsen, Bradley / Chandrasena, R Esala P / Qin, Zhihui / Sohn, Johann / Thatcher, Gregory R J / Bolton, Judy L

Chemico-biological interactions

2012 Volume 196, Issue 1-2, Page(s) 1–10

Abstract: o-Quinone forming estrogens and selective estrogen receptor modulators (SERMs) have been associated with carcinogenesis. LY2066948, a novel SERM in development by Eli Lilly for the treatment of uterine fibroids and myomas, has structural similarity to ... ...

Abstract	o-Quinone forming estrogens and selective estrogen receptor modulators (SERMs) have been associated with carcinogenesis. LY2066948, a novel SERM in development by Eli Lilly for the treatment of uterine fibroids and myomas, has structural similarity to the equine estrogen equilenin present in hormone replacement formulations; both contain a naphthol group susceptible to oxidative metabolism to o-quinones. LY2066948 was synthesized and assayed for antiestrogenic activity, and in cell culture was confirmed to be a more potent antiestrogen than the prototypical SERM, 4-hydroxytamoxifen. Oxidation of LY2066948 with 2-iodoxybenzoic acid gave an o-quinone (t(1/2)=3.9 ± 0.1h) which like 4-hydroxyequilenin-o-quinone (t(1/2)=2.5 ± 0.2 h) was observed to be exceptionally long-lived with the potential to cause cytotoxicity and/or genotoxicity. In model reactions with tyrosinase, the catechol metabolites of LY2066948 and equilenin were products; interestingly, in the presence of ascorbate to inhibit autoxidation, these catechols were formed quantitatively. Tyrosinase incubations in the presence of GSH gave the expected GSH conjugates resulting from trapping of the o-quinones, which were characterized by LC-MS/MS. Incubations of LY2066948 or equilenin with rat liver microsomes also gave detectable o-quinone trapped GSH conjugates; however, as observed with other SERMs, oxidative metabolism of LY2066948 mainly occurred on the amino side chain to yield the N-dealkylated metabolite. CYP1B1 is believed to be responsible for extra-hepatic generation of genotoxic estrogen quinones and o-quinone GSH conjugates were detected in equilenin incubations. However, in corresponding incubations with CYP1B1 supersomes, no o-quinone GSH conjugates of LY2066948 were detected. These studies suggest that although the naphthol group is susceptible to oxidative metabolism to long-lived o-quinones, the formation of these quinones by cytochrome P450 can be attenuated by the chemistry of the remainder of the molecule as in the case of LY2066948.
MeSH term(s)	Animals ; Aryl Hydrocarbon Hydroxylases/metabolism ; Cell Line, Tumor ; Cell Survival/drug effects ; Cytochrome P-450 CYP1B1 ; Cytochrome P-450 CYP3A/metabolism ; Dose-Response Relationship, Drug ; Equilenin/analogs & derivatives ; Equilenin/chemistry ; Equilenin/metabolism ; Female ; Half-Life ; Inhibitory Concentration 50 ; Kinetics ; Magnetic Resonance Spectroscopy ; Microsomes, Liver ; Naphthalenes/chemistry ; Naphthalenes/metabolism ; Naphthalenes/pharmacology ; Oxidation-Reduction ; Piperidines/chemistry ; Piperidines/metabolism ; Piperidines/pharmacology ; Quinones/chemistry ; Quinones/metabolism ; Quinones/pharmacology ; Rats ; Rats, Sprague-Dawley ; Selective Estrogen Receptor Modulators/chemistry ; Selective Estrogen Receptor Modulators/metabolism ; Selective Estrogen Receptor Modulators/pharmacology ; Tandem Mass Spectrometry
Chemical Substances	LY2066948 ; Naphthalenes ; Piperidines ; Quinones ; Selective Estrogen Receptor Modulators ; Aryl Hydrocarbon Hydroxylases (EC 1.14.14.1) ; CYP1B1 protein, human (EC 1.14.14.1) ; Cyp1b1 protein, rat (EC 1.14.14.1) ; Cytochrome P-450 CYP1B1 (EC 1.14.14.1) ; Cytochrome P-450 CYP3A (EC 1.14.14.1) ; CYP3A4 protein, human (EC 1.14.14.55) ; Equilenin (W8FTJ17C4J)
Language	English
Publishing date	2012-01-28
Publishing country	Ireland
Document type	Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	218799-1
ISSN	1872-7786 ; 0009-2797
ISSN (online)	1872-7786
ISSN	0009-2797
DOI	10.1016/j.cbi.2012.01.004
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Article ; Online: Problematic detoxification of estrogen quinones by NAD(P)H-dependent quinone oxidoreductase and glutathione-S-transferase.

Chandrasena, R Esala P / Edirisinghe, Praneeth D / Bolton, Judy L / Thatcher, Gregory R J

Chemical research in toxicology

2008 Volume 21, Issue 7, Page(s) 1324–1329

Abstract: Estrogen exposure through early menarche, late menopause, and hormone replacement therapy increases the risk factor for hormone-dependent cancers. Although the molecular mechanisms are not completely established, DNA damage by quinone electrophilic ... ...

Abstract	Estrogen exposure through early menarche, late menopause, and hormone replacement therapy increases the risk factor for hormone-dependent cancers. Although the molecular mechanisms are not completely established, DNA damage by quinone electrophilic reactive intermediates, derived from estrogen oxidative metabolism, is strongly implicated. A current hypothesis has 4-hydroxyestrone-o-quinone (4-OQE) acting as the proximal estrogen carcinogen, forming depurinating DNA adducts via Michael addition. One aspect of this hypothesis posits a key role for NAD(P)H-dependent quinone oxidoreductase (NQO1) in the reduction of 4-OQE and protection against estrogen carcinogenesis, despite two reports that 4-OQE is not a substrate for NQO1. 4-OQE is rapidly and efficiently trapped by GSH, allowing measurement of NADPH-dependent reduction of 4-OQE in the presence and absence of NQO1. 4-OQE was observed to be a substrate for NQO1, but the acceleration of NADPH-dependent reduction by NQO1 over the nonenzymic reaction is less than 10-fold and at more relevant nanomolar concentrations of substrate is less than 2-fold. An alternative detoxifying enzyme, glutathione-S-transferase, was observed to be a target for 4-OQE, rapidly undergoing covalent modification. These results indicate that a key role for NQO1 and GST in direct detoxification of 4-hydroxy-estrogen quinones is problematic.
MeSH term(s)	DNA Adducts ; DNA Damage ; Estrogens, Catechol/pharmacokinetics ; Glutathione Transferase/metabolism ; Humans ; Inactivation, Metabolic ; NAD(P)H Dehydrogenase (Quinone)/metabolism
Chemical Substances	DNA Adducts ; Estrogens, Catechol ; catechol estrogen 3,4-quinone ; NAD(P)H Dehydrogenase (Quinone) (EC 1.6.5.2) ; NQO1 protein, human (EC 1.6.5.2) ; Glutathione Transferase (EC 2.5.1.18)
Language	English
Publishing date	2008-07
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	639353-6
ISSN	1520-5010 ; 0893-228X
ISSN (online)	1520-5010
ISSN	0893-228X
DOI	10.1021/tx8000797
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Article: The naphthol selective estrogen receptor modulator (SERM), LY2066948, is oxidized to an o-quinone analogous to the naphthol equine estrogen, equilenin

Gherezghiher, Teshome B / Michalsen, Bradley / Chandrasena, R. Esala P / Qin, Zhihui / Sohn, Johann / Thatcher, Gregory R.J / Bolton, Judy L

Chemico-biological interactions. 2012 Mar. 5, v. 196, no. 1-2

2012

Abstract	o-Quinone forming estrogens and selective estrogen receptor modulators (SERMs) have been associated with carcinogenesis. LY2066948, a novel SERM in development by Eli Lilly for the treatment of uterine fibroids and myomas, has structural similarity to the equine estrogen equilenin present in hormone replacement formulations; both contain a naphthol group susceptible to oxidative metabolism to o-quinones. LY2066948 was synthesized and assayed for antiestrogenic activity, and in cell culture was confirmed to be a more potent antiestrogen than the prototypical SERM, 4-hydroxytamoxifen. Oxidation of LY2066948 with 2-iodoxybenzoic acid gave an o-quinone (t₁/₂=3.9±0.1h) which like 4-hydroxyequilenin-o-quinone (t₁/₂=2.5±0.2h) was observed to be exceptionally long-lived with the potential to cause cytotoxicity and/or genotoxicity. In model reactions with tyrosinase, the catechol metabolites of LY2066948 and equilenin were products; interestingly, in the presence of ascorbate to inhibit autoxidation, these catechols were formed quantitatively. Tyrosinase incubations in the presence of GSH gave the expected GSH conjugates resulting from trapping of the o-quinones, which were characterized by LC–MS/MS. Incubations of LY2066948 or equilenin with rat liver microsomes also gave detectable o-quinone trapped GSH conjugates; however, as observed with other SERMs, oxidative metabolism of LY2066948 mainly occurred on the amino side chain to yield the N-dealkylated metabolite. CYP1B1 is believed to be responsible for extra-hepatic generation of genotoxic estrogen quinones and o-quinone GSH conjugates were detected in equilenin incubations. However, in corresponding incubations with CYP1B1 supersomes, no o-quinone GSH conjugates of LY2066948 were detected. These studies suggest that although the naphthol group is susceptible to oxidative metabolism to long-lived o-quinones, the formation of these quinones by cytochrome P450 can be attenuated by the chemistry of the remainder of the molecule as in the case of LY2066948.
Keywords	aerobiosis ; autoxidation ; carcinogenesis ; catechol ; cell culture ; cytochrome P-450 ; cytotoxicity ; estrogen receptors ; estrogens ; genotoxicity ; horses ; liver microsomes ; metabolites ; quinones ; rats
Language	English
Dates of publication	2012-0305
Size	p. 1-10.
Publishing place	Elsevier Ireland Ltd
Document type	Article
ZDB-ID	218799-1
ISSN	1872-7786 ; 0009-2797
ISSN (online)	1872-7786
ISSN	0009-2797
DOI	10.1016/j.cbi.2012.01.004
Database	NAL-Catalogue (AGRICOLA)

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Article: Quinone formation as a chemoprevention strategy for hybrid drugs: balancing cytotoxicity and cytoprotection.

Dunlap, Tareisha / Chandrasena, R Esala P / Wang, Zhiqiang / Sinha, Vaishali / Wang, Zhican / Thatcher, Gregory R J

Chemical research in toxicology

2007 Volume 20, Issue 12, Page(s) 1903–1912

Abstract: Cellular defense mechanisms that respond to damage from oxidative and electrophilic stress, such as from quinones, represent a target for chemopreventive agents. Drugs bioactivated to quinones have the potential to activate antioxidant/electrophile ... ...

Abstract	Cellular defense mechanisms that respond to damage from oxidative and electrophilic stress, such as from quinones, represent a target for chemopreventive agents. Drugs bioactivated to quinones have the potential to activate antioxidant/electrophile responsive element (ARE) transcription of genes for cytoprotective phase 2 enzymes such as NAD(P)H-dependent quinone oxidoreductase (NQO1) but can also cause cellular damage. Two isomeric families of compounds were prepared, including the NO-NSAIDs (NO-donating nonsteroidal anti-inflammatory drugs) NCX 4040 and NCX 4016; one family was postulated to release a quinone methide on esterase bioactivation. The study of reactivity and GSH conjugation in model and cell systems confirmed the postulate. The quinone-forming family, including NCX 4040 and conisogenic bromides and mesylate, was rapidly bioactivated to a quinone, which gave activation of ARE and consequent induction of NQO1 in liver cells. Although the control family, including NCX 4016 and conisogenic bromides and mesylates, cannot form a quinone, ARE activation and NQO1 induction were observed, compatible with slower SN2 reactions with thiol sensor proteins, and consequent ARE-luciferase and NQO1 induction. Using a Chemoprevention Index estimate, the quinone-forming compounds suffered because of high cytoxicity and were more compatible with cancer therapy than chemoprevention. In the Comet assay, NCX 4040 was highly genotoxic relative to NCX 4016. There was no evidence that NO contributes to the observed biological activity and no evidence that NCX 4040 is an NO donor, instead, rapidly releasing NO3- and quinone. These results indicate a strategy for studying the quinone biological activity and reinforce the therapeutic attributes of NO-ASA through structural elements other than NO and ASA.
MeSH term(s)	Animals ; Anti-Inflammatory Agents, Non-Steroidal/adverse effects ; Anti-Inflammatory Agents, Non-Steroidal/metabolism ; Anti-Inflammatory Agents, Non-Steroidal/pharmacology ; Aspirin/adverse effects ; Aspirin/analogs & derivatives ; Aspirin/metabolism ; Aspirin/pharmacology ; Benzoquinones/metabolism ; Catalysis ; Cell Line, Tumor ; Cell Survival/drug effects ; Chemoprevention ; Cytoprotection ; Esterases/metabolism ; Glutathione/metabolism ; Liver/drug effects ; Liver/enzymology ; Liver/metabolism ; Luciferases/genetics ; Metabolic Detoxication, Phase II ; Mice ; Models, Biological ; NAD(P)H Dehydrogenase (Quinone) ; NADPH Dehydrogenase/biosynthesis ; NADPH Dehydrogenase/genetics ; Nitro Compounds/adverse effects ; Nitro Compounds/metabolism ; Nitro Compounds/pharmacology ; Response Elements/genetics ; Swine
Chemical Substances	Anti-Inflammatory Agents, Non-Steroidal ; Benzoquinones ; NCX 4040 ; Nitro Compounds ; quinone (3T006GV98U) ; Luciferases (EC 1.13.12.-) ; NAD(P)H Dehydrogenase (Quinone) (EC 1.6.5.2) ; Nqo1 protein, mouse (EC 1.6.5.2) ; NADPH Dehydrogenase (EC 1.6.99.1) ; Esterases (EC 3.1.-) ; nitroaspirin (EH04H13L6B) ; Glutathione (GAN16C9B8O) ; Aspirin (R16CO5Y76E)
Language	English
Publishing date	2007-12
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	639353-6
ISSN	1520-5010 ; 0893-228X
ISSN (online)	1520-5010
ISSN	0893-228X
DOI	10.1021/tx7002257
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Article ; Online: Proteomic and mass spectroscopic quantitation of protein S-nitrosation differentiates NO-donors.

Sinha, Vaishali / Wijewickrama, Gihani T / Chandrasena, R Esala P / Xu, Hua / Edirisinghe, Praneeth D / Schiefer, Isaac T / Thatcher, Gregory R J

ACS chemical biology

2010 Volume 5, Issue 7, Page(s) 667–680

Abstract: Protein S-nitrosation has been argued to be the most important signaling pathway mediating the bioactivity of NO. This post-translational modification of protein thiols is the result of chemical nitrosation of cysteine residues. The term NO-donors covers ...

Abstract	Protein S-nitrosation has been argued to be the most important signaling pathway mediating the bioactivity of NO. This post-translational modification of protein thiols is the result of chemical nitrosation of cysteine residues. The term NO-donors covers very different chemical classes, from clinical therapeutics to probes of routine use in chemical biology; their different chemistry is predicted to result in distinctive biology regulated by protein S-nitrosation. To measure the extent of protein S-nitrosation by NO-donors, a proteomic mass spectrometry method was developed, which quantitates free thiol versus nitrosothiol for each modified cysteine residue, coined d-Switch. This method is adapted from the biotin switch (BST) method, used extensively to identify S-nitrosated proteins in complex biological mixtures; however, BST does not quantitate free thiol. Since glutathione-S-transferase P1-1 (GST-P1) has been proposed to be a biological "NO-carrier", GST-P1 was used as a reporter protein. The 5 different chemical classes of NO-donors compared by d-Switch demonstrated very different profiles of protein S-nitrosation and response to O(2) and cysteine, although all NO-donors were oxidants toward GST-P1. The low limits of detection and the ability to use established MS database searching allowed facile generalization of the d-Switch method. Therefore after incubation of neuronal cell cultures with nitrosothiol, it was possible to quantitate not only S-nitrosation of GST-P1 but also many other proteins, including novel targets such as ubiquitin carboxyl-terminal esterase L1 (UCHL1). Moreover, d-Switch also allowed identification of non-nitrosated proteins and quantitation of degree of nitrosation for individual protein thiols.
MeSH term(s)	Biotin/analogs & derivatives ; Biotin/metabolism ; Cells, Cultured ; Cysteine/analogs & derivatives ; Cysteine/chemistry ; Cysteine/metabolism ; Glutathione S-Transferase pi/metabolism ; Humans ; Mass Spectrometry ; Neuroblastoma/metabolism ; Nitric Oxide/metabolism ; Nitric Oxide Donors/chemistry ; Nitric Oxide Donors/metabolism ; Nitrosation ; Proteins/chemistry ; Proteins/metabolism ; Proteomics ; S-Nitrosoglutathione/metabolism ; S-Nitrosothiols/chemistry ; S-Nitrosothiols/metabolism ; S-Nitrosothiols/pharmacology
Chemical Substances	Nitric Oxide Donors ; Proteins ; S-Nitrosothiols ; Nitric Oxide (31C4KY9ESH) ; S-Nitrosoglutathione (57564-91-7) ; Biotin (6SO6U10H04) ; S-nitrosocysteine (926P2322P4) ; Glutathione S-Transferase pi (EC 2.5.1.18) ; Cysteine (K848JZ4886)
Language	English
Publishing date	2010-06-04
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural
ISSN	1554-8937
ISSN (online)	1554-8937
DOI	10.1021/cb100054m
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Article: Formation of compound I by photo-oxidation of compound II.

Zhang, Rui / Chandrasena, R Esala P / Martinez, Enrique / Horner, John H / Newcomb, Martin

Organic letters

2005 Volume 7, Issue 6, Page(s) 1193–1195

Abstract: reaction: see text] Compound I is the heme-iron(IV)-oxo porphyrin radical cation formed in peroxidase and catalase enzymes by reaction with hydrogen peroxide. As an alternative to chemical oxidations of porphyrin-iron(III) species, various compound I ... ...

Abstract	[reaction: see text] Compound I is the heme-iron(IV)-oxo porphyrin radical cation formed in peroxidase and catalase enzymes by reaction with hydrogen peroxide. As an alternative to chemical oxidations of porphyrin-iron(III) species, various compound I species were produced by 355 nm laser flash photolysis photooxidation of the corresponding compound II species, porphyrin-iron(IV)-oxo derivatives. The method is demonstrated by production and kinetic studies of the compound I species from 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin-iron, from horseradish peroxidase, and from wild-type horse skeletal myoglobin.
MeSH term(s)	Animals ; Horseradish Peroxidase/metabolism ; Horses ; Iron/chemistry ; Kinesics ; Metalloporphyrins/chemical synthesis ; Metalloporphyrins/chemistry ; Myoglobin/chemistry ; Oxidation-Reduction ; Photochemistry/methods
Chemical Substances	Metalloporphyrins ; Myoglobin ; ferryl iron (14127-53-8) ; Iron (E1UOL152H7) ; Horseradish Peroxidase (EC 1.11.1.-)
Language	English
Publishing date	2005-03-17
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Research Support, U.S. Gov't, P.H.S.
ISSN	1523-7060
ISSN	1523-7060
DOI	10.1021/ol050296j
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Article: Hydroxylation by the hydroperoxy-iron species in cytochrome P450 enzymes.

Chandrasena, R Esala P / Vatsis, Kostas P / Coon, Minor J / Hollenberg, Paul F / Newcomb, Martin

Journal of the American Chemical Society

2004 Volume 126, Issue 1, Page(s) 115–126

Abstract: Intramolecular and intermolecular kinetic isotope effects (KIEs) were determined for hydroxylation of the enantiomers of trans-2-(p-trifluoromethylphenyl)cyclopropylmethane (1) by hepatic cytochrome P450 enzymes, P450s 2B1, Delta2B4, Delta2B4 T302A, ... ...

Abstract	Intramolecular and intermolecular kinetic isotope effects (KIEs) were determined for hydroxylation of the enantiomers of trans-2-(p-trifluoromethylphenyl)cyclopropylmethane (1) by hepatic cytochrome P450 enzymes, P450s 2B1, Delta2B4, Delta2B4 T302A, Delta2E1, and Delta2E1 T303A. Two products from oxidation of the methyl group were obtained, unrearranged trans-2-(p-trifluoromethylphenyl)cyclopropylmethanol (2) and rearranged 1-(p-trifluoromethylphenyl)but-3-en-1-ol (3). In intramolecular KIE studies with dideuteriomethyl substrates (1-d(2)) and in intermolecular KIE studies with mixtures of undeuterated (1-d(0)) and trideuteriomethyl (1-d(3)) substrates, the apparent KIE for product 2 was consistently larger than the apparent KIE for product 3 by a factor of ca. 1.2. Large intramolecular KIEs found with 1-d(2) (k(H)/k(D) = 9-11 at 10 degrees C) were shown not to be complicated by tunneling effects by variable temperature studies with two P450 enzymes. The results require two independent isotope-sensitive processes in the overall hydroxylation reactions that are either competitive or sequential. Intermolecular KIEs were partially masked in all cases and largely masked for some P450s. The intra- and intermolecular KIE results were combined to determine the relative rate constants for the unmasking and hydroxylation reactions, and a qualitative correlation was found for the unmasking reaction and release of hydrogen peroxide from four of the P450 enzymes in the absence of substrate. The results are consistent with the two-oxidants model for P450 (Vaz, A. D. N.; McGinnity, D. F.; Coon, M. J. Proc. Natl. Acad. Sci. U.S.A. 1998, 95, 3555), which postulates that a hydroperoxy-iron species (or a protonated analogue of this species) is a viable electrophilic oxidant in addition to the consensus oxidant, iron-oxo.
MeSH term(s)	Cyclopropanes/chemistry ; Cyclopropanes/metabolism ; Cytochrome P-450 Enzyme System/chemistry ; Cytochrome P-450 Enzyme System/metabolism ; Deuterium Exchange Measurement ; Gas Chromatography-Mass Spectrometry ; Hydroxylation ; Isoenzymes/chemistry ; Isoenzymes/metabolism ; Kinetics ; NADP/chemistry ; NADP/metabolism ; Stereoisomerism
Chemical Substances	Cyclopropanes ; Isoenzymes ; NADP (53-59-8) ; Cytochrome P-450 Enzyme System (9035-51-2)
Language	English
Publishing date	2004-01-14
Publishing country	United States
Document type	Journal Article ; Research Support, U.S. Gov't, P.H.S.
ZDB-ID	3155-0
ISSN	1520-5126 ; 0002-7863
ISSN (online)	1520-5126
ISSN	0002-7863
DOI	10.1021/ja038237t
Database	MEDical Literature Analysis and Retrieval System OnLINE

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