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Drake DM, Afsharian K, Or B, Shapiro AM, Lai ML, Miller L, Wells PG. BRCA1 protein dose-dependent risk for embryonic oxidative DNA damage, embryopathies and neurodevelopmental disorders with and without ethanol exposure. Redox Biol 2024; 70:103070. [PMID: 38359745 PMCID: PMC10877410 DOI: 10.1016/j.redox.2024.103070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 01/30/2024] [Indexed: 02/17/2024] Open
Abstract
Although widely known as a tumor suppressor, the breast cancer 1 susceptibility protein (BRCA1) is also important in development, where it regulates fetal DNA repair pathways that protect against DNA damage caused by physiological and drug-enhanced levels of reactive oxygen species (ROS). We previously showed that conditional heterozygous (+/-) knockout (cKO) mouse embryos with a minor 28% BRCA1 deficiency developed normally in culture, but when exposed to the ROS-initiating drug, alcohol (ethanol, EtOH), exhibited embryopathies not evident in wild-type (+/+) littermates. Herein, we characterized a directBrca1 +/- knockout (KO) model with a 2-fold greater (58%) reduction in BRCA1 protein vs. the cKO model. We also characterized and compared learning & memory deficits in both the cKO and KO models. Even saline-exposed Brca1 +/- vs. +/+ KO progeny exhibited enhanced oxidative DNA damage and embryopathies in embryo culture and learning & memory deficits in females in vivo, which were not observed in the cKO model, revealing the potential pathogenicity of physiological ROS levels. The embryopathic EtOH concentration for cultured direct KO embryos was half that for cKO embryos, and EtOH affected Brca1 +/+ embryos only in the direct KO model. The spectrum and severity of EtOH embryopathies in culture were greater in both Brca1 +/- vs. +/+ embryos, and direct KO vs. cKO +/- embryos. Motor coordination deficits were evident in both male and female Brca1 +/- KO progeny exposed in utero to EtOH. The results in our direct KO model with a greater BRCA1 deficiency vs. cKO mice provide the first evidence for BRCA1 protein dose-dependent susceptibility to developmental disorders caused by physiological and drug-enhanced oxidative stress.
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Affiliation(s)
- Danielle M Drake
- Department of Pharmaceutical Sciences and Centre for Pharmaceutical Oncology, Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Kian Afsharian
- Department of Pharmaceutical Sciences and Centre for Pharmaceutical Oncology, Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Benjamin Or
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Aaron M Shapiro
- Department of Pharmaceutical Sciences and Centre for Pharmaceutical Oncology, Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Michelle L Lai
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Lutfiya Miller
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Peter G Wells
- Department of Pharmaceutical Sciences and Centre for Pharmaceutical Oncology, Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada; Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
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Drake DM, Zhen D, Kerrebijn I, Or B, Gao S, Afsharian K, Tran J, Bhatia S, Cheng A, Wells PG. Breast cancer 1 (BRCA1) protection in altered gene expression and neurodevelopmental disorders due to physiological and ethanol-enhanced reactive oxygen species formation. Free Radic Biol Med 2023; 208:272-284. [PMID: 37541454 DOI: 10.1016/j.freeradbiomed.2023.08.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 06/08/2023] [Accepted: 08/02/2023] [Indexed: 08/06/2023]
Abstract
The breast cancer 1 (Brca1) susceptibility gene regulates the repair of reactive oxygen species (ROS)-mediated DNA damage, which is implicated in neurodevelopmental disorders. Alcohol (ethanol, EtOH) exposure during pregnancy causes fetal alcohol spectrum disorders (FASD), including abnormal brain function, associated with enhanced ROS-initiated DNA damage. Herein, oxidative DNA damage in fetal brains and neurodevelopmental disorders were enhanced in saline-exposed +/- vs. +/+ Brca1 littermates. A single EtOH exposure during gestation further enhanced oxidative DNA damage, altered the expression of developmental/DNA damage response genes in fetal brains, and resulted in neurodevelopmental disorders, all of which were BRCA1-dependent. Pretreatment with the ROS inhibitor phenylbutylnitrone (PBN) blocked DNA damage and some neurodevelopmental disorders in both saline- and EtOH-exposed progeny, corroborating a ROS-dependent mechanism. Fetal BRCA1 protects against altered gene expression and neurodevelopmental disorders caused by both physiological and EtOH-enhanced levels of ROS formation. BRCA1 deficiencies may enhance the risk for FASD.
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Affiliation(s)
- Danielle M Drake
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada; Centre for Pharmaceutical Oncology, Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Danlin Zhen
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Isabel Kerrebijn
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Benjamin Or
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Sophie Gao
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Kian Afsharian
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada; Centre for Pharmaceutical Oncology, Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Jason Tran
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Shama Bhatia
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada; Centre for Pharmaceutical Oncology, Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Ashley Cheng
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada; Centre for Pharmaceutical Oncology, Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Peter G Wells
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada; Centre for Pharmaceutical Oncology, Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada; Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
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Drake DM, Wells PG. Novel mechanisms in alcohol neurodevelopmental disorders via BRCA1 depletion and BRCA1-dependent NADPH oxidase regulation. Redox Biol 2021; 48:102148. [PMID: 34736119 PMCID: PMC8577473 DOI: 10.1016/j.redox.2021.102148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 09/20/2021] [Accepted: 09/20/2021] [Indexed: 11/27/2022] Open
Abstract
The breast cancer 1 protein (BRCA1) facilitates DNA repair, preventing embryolethality and protecting the fetus from reactive oxygen species (ROS)-induced developmental disorders mediated by oxidatively damaged DNA. Alcohol (ethanol, EtOH) exposure during pregnancy causes fetal alcohol spectrum disorders (FASD), characterized by aberrant behaviour and enhanced ROS formation and proteasomal protein degradation. Herein, ROS-producing NADPH oxidase (NOX) activity was higher in Brca1 +/- vs. +/+ fetal and adult brains, and further enhanced by a single EtOH exposure. EtOH also enhanced catalase and proteasomal activities, while conversely reducing BRCA1 protein levels without affecting Brca1 gene expression. EtOH-initiated adaptive postnatal freezing behaviour was lost in Brca1 +/- progeny. Pretreatment with the free radical spin trap and ROS inhibitor phenylbutylnitrone blocked all EtOH effects, suggesting ROS-dependent mechanisms. This is the first in vivo evidence of NOX regulation by BRCA1, and of EtOH-induced, ROS-mediated depletion of BRCA1, revealing novel mechanisms of BRCA1 protection in FASD.
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Affiliation(s)
- Danielle M Drake
- Department of Pharmaceutical Sciences and Centre for Pharmaceutical Oncology, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Peter G Wells
- Department of Pharmaceutical Sciences and Centre for Pharmaceutical Oncology, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada; Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
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Bhatia S, Drake DM, Miller L, Wells PG. Oxidative stress and DNA damage in the mechanism of fetal alcohol spectrum disorders. Birth Defects Res 2019; 111:714-748. [PMID: 31033255 DOI: 10.1002/bdr2.1509] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 03/07/2019] [Accepted: 03/14/2019] [Indexed: 12/18/2022]
Abstract
This review covers molecular mechanisms involving oxidative stress and DNA damage that may contribute to morphological and functional developmental disorders in animal models resulting from exposure to alcohol (ethanol, EtOH) in utero or in embryo culture. Components covered include: (a) a brief overview of EtOH metabolism and embryopathic mechanisms other than oxidative stress; (b) mechanisms within the embryo and fetal brain by which EtOH increases the formation of reactive oxygen species (ROS); (c) critical embryonic/fetal antioxidative enzymes and substrates that detoxify ROS; (d) mechanisms by which ROS can alter development, including ROS-mediated signal transduction and oxidative DNA damage, the latter of which leads to pathogenic genetic (mutations) and epigenetic changes; (e) pathways of DNA repair that mitigate the pathogenic effects of DNA damage; (f) related indirect mechanisms by which EtOH enhances risk, for example by enhancing the degradation of some DNA repair proteins; and, (g) embryonic/fetal pathways like NRF2 that regulate the levels of many of the above components. Particular attention is paid to studies in which chemical and/or genetic manipulation of the above mechanisms has been shown to alter the ability of EtOH to adversely affect development. Alterations in the above components are also discussed in terms of: (a) individual embryonic and fetal determinants of risk and (b) potential risk biomarkers and mitigating strategies. FASD risk is likely increased in progeny which/who are biochemically predisposed via genetic and/or environmental mechanisms, including enhanced pathways for ROS formation and/or deficient pathways for ROS detoxification or DNA repair.
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Affiliation(s)
- Shama Bhatia
- Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada.,Centre for Pharmaceutical Oncology, University of Toronto, Toronto, Ontario, Canada
| | - Danielle M Drake
- Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada.,Centre for Pharmaceutical Oncology, University of Toronto, Toronto, Ontario, Canada
| | | | - Peter G Wells
- Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada.,Centre for Pharmaceutical Oncology, University of Toronto, Toronto, Ontario, Canada.,Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada
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Abstract
Known for its tumor suppressor activity in breast and ovarian cancers, the breast cancer 1 susceptibility gene (Brca1) is involved in a variety of cellular pathways including DNA repair, antioxidant signaling, apoptosis, and cell cycle regulation. BRCA1 can translocate between the cytoplasm and nucleus to perform its various roles. Herein is a procedure for measuring BRCA1 protein levels in the whole cell lysate (WCL), as well as in the nuclear (N) and cytoplasmic (C) fractions of mouse tissues at different gestational ages. The method employs multiple loading controls to ensure proper separation of fractions and a total protein stain for more consistent comparisons of dissimilar samples. This method is useful for identifying BRCA1 deficiencies and localization in a variety of research fields, including development, neurodegeneration, and cancer.
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Affiliation(s)
- Danielle M Drake
- Department of Pharmaceutical Sciences and Centre for Pharmaceutical Oncology, University of Toronto, Toronto, ON, Canada
| | - Peter G Wells
- Department of Pharmaceutical Sciences and Centre for Pharmaceutical Oncology, University of Toronto, Toronto, ON, Canada.
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada.
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Drake DM, Shapiro AM, Wells PG. Measurement of the Oxidative DNA Lesion 8-Oxoguanine (8-oxoG) by ELISA or by High-Performance Liquid Chromatography (HPLC) with Electrochemical Detection. Methods Mol Biol 2019; 1965:313-328. [PMID: 31069684 DOI: 10.1007/978-1-4939-9182-2_21] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Reactive oxygen species (ROS) can oxidize cellular macromolecules like DNA, causing DNA damage. The most common form of DNA damage is the 8-oxoguanine (8-oxoG) lesion, typically repaired by the base excision repair (BER) pathway, which is initiated by the enzyme oxoguanine glycosylase 1 (OGG1). ROS are produced endogenously and can be enhanced by environmental factors, such as xenobiotics, radiation, and microbial pathogens. As a commonly used biomarker of oxidative damage, 8-oxoG can be measured in two different ways described herein. Commercially available ELISA kits allow for easy detection of the 8-oxoG lesion, while more difficult HPLC assays with UV and electrochemical detection allow for a more definitive identification and quantification of 8-oxoG.
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Affiliation(s)
- Danielle M Drake
- Department of Pharmaceutical Sciences and Centre for Pharmaceutical Oncology, University of Toronto, Toronto, ON, Canada
| | - Aaron M Shapiro
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, ON, Canada
- British Columbia Provincial Toxicology Centre, Vancouver, BC, Canada
| | - Peter G Wells
- Department of Pharmaceutical Sciences and Centre for Pharmaceutical Oncology, University of Toronto, Toronto, ON, Canada.
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada.
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Wells PG, Bhatia S, Drake DM, Miller-Pinsler L. Fetal oxidative stress mechanisms of neurodevelopmental deficits and exacerbation by ethanol and methamphetamine. ACTA ACUST UNITED AC 2017; 108:108-30. [PMID: 27345013 DOI: 10.1002/bdrc.21134] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 06/09/2016] [Indexed: 11/06/2022]
Abstract
In utero exposure of mouse progeny to alcohol (ethanol, EtOH) and methamphetamine (METH) causes substantial postnatal neurodevelopmental deficits. One emerging pathogenic mechanism underlying these deficits involves fetal brain production of reactive oxygen species (ROS) that alter signal transduction, and/or oxidatively damage cellular macromolecules like lipids, proteins, and DNA, the latter leading to altered gene expression, likely via non-mutagenic mechanisms. Even physiological levels of fetal ROS production can be pathogenic in biochemically predisposed progeny, and ROS formation can be enhanced by drugs like EtOH and METH, via activation/induction of ROS-producing NADPH oxidases (NOX), drug bioactivation to free radical intermediates by prostaglandin H synthases (PHS), and other mechanisms. Antioxidative enzymes, like catalase in the fetal brain, while low, provide critical protection. Oxidatively damaged DNA is normally rapidly repaired, and fetal deficiencies in several DNA repair proteins, including oxoguanine glycosylase 1 (OGG1) and breast cancer protein 1 (BRCA1), enhance the risk of drug-initiated postnatal neurodevelopmental deficits, and in some cases deficits in untreated progeny, the latter of which may be relevant to conditions like autism spectrum disorders (ASD). Risk is further regulated by fetal nuclear factor erythroid 2-related factor 2 (Nrf2), a ROS-sensing protein that upregulates an array of proteins, including antioxidative enzymes and DNA repair proteins. Imbalances between conceptal pathways for ROS formation, versus those for ROS detoxification and DNA repair, are important determinants of risk. Birth Defects Research (Part C) 108:108-130, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Peter G Wells
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, University of Toronto, Toronto, Canada.,Department of Pharmacology & Toxicology, Faculty of Medicine, University of Toronto, Toronto, Canada
| | - Shama Bhatia
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, University of Toronto, Toronto, Canada
| | - Danielle M Drake
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, University of Toronto, Toronto, Canada
| | - Lutfiya Miller-Pinsler
- Department of Pharmacology & Toxicology, Faculty of Medicine, University of Toronto, Toronto, Canada
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Boynton WV, Feldman WC, Squyres SW, Prettyman TH, Bruckner J, Evans LG, Reedy RC, Starr R, Arnold JR, Drake DM, Englert PAJ, Metzger AE, Mitrofanov I, Trombka JI, D'Uston C, Wanke H, Gasnault O, Hamara DK, Janes DM, Marcialis RL, Maurice S, Mikheeva I, Taylor GJ, Tokar R, Shinohara C. Distribution of hydrogen in the near surface of Mars: evidence for subsurface ice deposits. Science 2002; 297:81-5. [PMID: 12040090 DOI: 10.1126/science.1073722] [Citation(s) in RCA: 753] [Impact Index Per Article: 34.2] [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: 11/02/2022]
Abstract
Using the Gamma-Ray Spectrometer on the Mars Odyssey, we have identified two regions near the poles that are enriched in hydrogen. The data indicate the presence of a subsurface layer enriched in hydrogen overlain by a hydrogen-poor layer. The thickness of the upper layer decreases with decreasing distance to the pole, ranging from a column density of about 150 grams per square centimeter at -42 degrees latitude to about 40 grams per square centimeter at -77 degrees. The hydrogen-rich regions correlate with regions of predicted ice stability. We suggest that the host of the hydrogen in the subsurface layer is ice, which constitutes 35 +/- 15% of the layer by weight.
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Affiliation(s)
- W V Boynton
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA.
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Cronin SN, Freeman LH, Ryan G, Drake DM. Recovery after percutaneous transluminal coronary angioplasty: assessment after discharge. Crit Care Nurse 2000. [DOI: 10.4037/ccn2000.20.2.70] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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Cronin SN, Freeman LH, Ryan G, Drake DM. Recovery after percutaneous transluminal coronary angioplasty: assessment after discharge. Crit Care Nurse 2000; 20:70-3, 75-6. [PMID: 11873753] [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: 02/24/2023]
MESH Headings
- Aftercare/methods
- Aged
- Aged, 80 and over
- Angioplasty, Balloon, Coronary/adverse effects
- Angioplasty, Balloon, Coronary/nursing
- Angioplasty, Balloon, Coronary/psychology
- Angioplasty, Balloon, Coronary/rehabilitation
- Attitude to Health
- Cross-Sectional Studies
- Ethical Analysis
- Female
- Health Behavior
- Health Knowledge, Attitudes, Practice
- Humans
- Life Style
- Male
- Middle Aged
- Myocardial Ischemia/therapy
- Needs Assessment
- Nursing Assessment/methods
- Patient Education as Topic/methods
- Recovery of Function
- Recurrence
- Time Factors
- Treatment Outcome
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Affiliation(s)
- S N Cronin
- Lansing School of Nursing, Bellarmine College, Louisville, KY, USA
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Rosenzweig DP, Amann JF, Boudrie RL, Doss KG, Drake DM, Halpern I, Khandaker MA, Nelson J, Storm DW, Tieger DR, Wood SA. Comparison of inclusive inelastic scattering of pi + and pi - from nuclei at 100 MeV. Phys Rev C Nucl Phys 1992; 46:1968-1973. [PMID: 9968315 DOI: 10.1103/physrevc.46.1968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Håkansson A, Lindholm A, Nilsson L, Blomgren J, Söderman P, Drake DM, Wender SA, Olsson N. 12C(n, gamma 0)13C cross section in the 8-11 MeV region. Phys Rev C Nucl Phys 1990; 41:2556-2559. [PMID: 9966636 DOI: 10.1103/physrevc.41.2556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Arscott LD, Drake DM, Williams CH. Inactivation-reactivation of two-electron reduced Escherichia coli glutathione reductase involving a dimer-monomer equilibrium. Biochemistry 1989; 28:3591-8. [PMID: 2663073 DOI: 10.1021/bi00434a066] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [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: 01/02/2023]
Abstract
Glutathione reductase from Escherichia coli is inactivated when incubated with either NADPH or NADH. The process is inversely dependent on the enzyme concentration. Inactivation is rapid and monophasic with 1 microM NADPH and 1 nM enzyme FAD giving a t1/2 of 1 min. Complex formation between NADPH and the two-electron reduced enzyme (EH2) at higher levels of NADPH protects against rapid inactivation. NADP+, produced in a side reaction with oxygen, also protects by forming a complex with EH2. These complexes make analysis of the concentration dependence of the inactivation process difficult. Inactivation with NADH, where complexes do not interfere, is slower but can be analyzed more readily. With 152 microM NADH and 5.4 nM enzyme FAD, the time required for 50% inactivation is 17 min. The process is markedly biphasic, reaching the final inactivation level after 5-7 h. Analysis of the relationship between the final level of inactivation with NADH and the enzyme concentration indicates that inactivation is due to dissociation of the normally dimeric enzyme. Thus, the position of the dimer-monomer equilibrium between an active dimeric two-electron reduced species and an inactive monomeric two-electron reduced form determines the enzyme activity. An apparent equilibrium constant (Kd) for dissociation of dimer obtained from the anaerobic concentration dependent inactivation curves is 220 nM. Enzyme inactivated with NADH can be reactivated with glutathione, and the reactivation kinetics are second order, monomer-monomer over 75% of the reaction with an average apparent association rate constant (ka) of 13.1 (+/- 5.5) X 10(6) M-1 min-1.
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Affiliation(s)
- L D Arscott
- Veterans Administration Medical Center, Ann Arbor, Michigan
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Bruge G, Garreta D, Birien P, Catz H, Chaumeaux A, Janouin S, Legrand D, Lemaire MC, Mayer B, Pain J, Perrot F, Aslanides E, Bing O, Drake DM, Peng JC, Berrada M, Bocquet JP, Monnand E, Mougey J, Perrin P, Lichtenstadt J, Yavin AI. Elastic scattering of 179.3 MeV antiprotons by deuterium. Phys Rev C Nucl Phys 1988; 37:1345-1346. [PMID: 9954581 DOI: 10.1103/physrevc.37.1345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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McDaniels DK, Tinsley JR, Lisantti J, Drake DM, Bergqvist I, Swenson LW, Bertrand FE, Gross EE, Horen DJ, Sjoreen TP, Liljestrand R, Wilson H. Cross section and analyzing power measurements for the giant resonance region in 208Pb with 200-MeV protons. Phys Rev C Nucl Phys 1986; 33:1943-1954. [PMID: 9953374 DOI: 10.1103/physrevc.33.1943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Morgan GL, Lisowski PW, Wender SA, Brown RE, Jarmie N, Wilkerson JF, Drake DM. Measurement of the branching ratio 3H(d, gamma )/3H(d,n) using thick tritium gas targets. Phys Rev C Nucl Phys 1986; 33:1224-1227. [PMID: 9953265 DOI: 10.1103/physrevc.33.1224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Dousse JC, Arthur ED, Drake DM, Gursky J, Moses JD, Stein N, Sunier JW. Coincident neutron-proton emission from proton bombardment of 87Sr and 91Zr. Phys Rev C Nucl Phys 1985; 32:92-102. [PMID: 9952807 DOI: 10.1103/physrevc.32.92] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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