1
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Photopolymerization with EDTA and Riboflavin for Proteins Analysis in Polyacrylamide Gel Electrophoresis. Protein J 2022; 41:438-443. [PMID: 35895218 DOI: 10.1007/s10930-022-10068-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/12/2022] [Indexed: 10/16/2022]
Abstract
A new method for photosensitized polymerization of polyacrylamide gels was proposed. Photopolymerization of acrylamide/N,N'-methylenebisacrylamide (AM/Bis) was assisted with combination of catalyst ethylenediaminetetraacetic acid disodium salt dihydrate (EDTA) and photoinitiator riboflavin (RF). The prepared cross-linked AM/Bis + EDTA/RF gels were tested in electrophoretic SDS-PAGE system at high concentration of AM (20 wt%). The efficiency of these systems for electrophoretic separation of histones of human blood lymphocytes was demonstrated. In principle, such gels with small pores in the separation zone can offer advantages for resolution of proteins. The advantages of proposed method also include simple technique and possibility of gel preparation in a timely manner (for 10-15 min). However, in microporous gel systems some limitations in electroblotting technique could occur, which is particularly crucial for hydrophobic proteins.
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2
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Kale RS, Seep JL, Sallans L, Frankel LK, Bricker TM. Oxidative modification of LHC II associated with photosystem II and PS I-LHC I-LHC II membranes. PHOTOSYNTHESIS RESEARCH 2022; 152:261-274. [PMID: 35179681 DOI: 10.1007/s11120-022-00902-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 02/01/2022] [Indexed: 05/22/2023]
Abstract
Under aerobic conditions the production of Reactive Oxygen Species (ROS) by electron transport chains is unavoidable, and occurs in both autotrophic and heterotrophic organisms. In photosynthetic organisms both Photosystem II (PS II) and Photosystem I (PS I), in addition to the cytochrome b6/f complex, are demonstrated sources of ROS. All of these membrane protein complexes exhibit oxidative damage when isolated from field-grown plant material. An additional possible source of ROS in PS I and PS II is the distal, chlorophyll-containing light-harvesting array LHC II, which is present in both photosystems. These serve as possible sources of 1O2 produced by the interaction of 3O2 with 3chl* produced by intersystem crossing. We have hypothesized that amino acid residues close to the sites of ROS generation will be more susceptible to oxidative modification than distant residues. In this study, we have identified oxidized amino acid residues in a subset of the spinach LHC II proteins (Lhcb1 and Lhcb2) that were associated with either PS II membranes (i.e. BBYs) or PS I-LHC I-LHC II membranes, both of which were isolated from field-grown spinach. We identified oxidatively modified residues by high-resolution tandem mass spectrometry. Interestingly, two different patterns of oxidative modification were evident for the Lhcb1 and Lhcb2 proteins from these different sources. In the LHC II associated with PS II membranes, oxidized residues were identified to be located on the stromal surface of Lhcb1 and, to a much lesser extent, Lhcb2. Relatively few oxidized residues were identified as buried in the hydrophobic core of these proteins. The LHC II associated with PS I-LHC I-LHC II membranes, however, exhibited fewer surface-oxidized residues but, rather a large number of oxidative modifications buried in the hydrophobic core regions of both Lhcb1 and Lhcb2, adjacent to the chlorophyll prosthetic groups. These results appear to indicate that ROS, specifically 1O2, can modify the Lhcb proteins associated with both photosystems and that the LHC II associated with PS II membranes represent a different population from the LHC II associated with PS I-LHC I-LHC II membranes.
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Affiliation(s)
- Ravindra S Kale
- Department of Biological Sciences, Biochemistry and Molecular Biology Section, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Jacob L Seep
- Department of Biological Sciences, Biochemistry and Molecular Biology Section, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Larry Sallans
- The Rieveschl Laboratories for Mass Spectrometry, Department of Chemistry, University of Cincinnati, Cincinnati, OH, 45221, USA
| | - Laurie K Frankel
- Department of Biological Sciences, Biochemistry and Molecular Biology Section, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Terry M Bricker
- Department of Biological Sciences, Biochemistry and Molecular Biology Section, Louisiana State University, Baton Rouge, LA, 70803, USA.
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3
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Tocopherol controls D1 amino acid oxidation by oxygen radicals in Photosystem II. Proc Natl Acad Sci U S A 2021; 118:2019246118. [PMID: 33479170 DOI: 10.1073/pnas.2019246118] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Photosystem II (PSII) is an intrinsic membrane protein complex that functions as a light-driven water:plastoquinone oxidoreductase in oxygenic photosynthesis. Electron transport in PSII is associated with formation of reactive oxygen species (ROS) responsible for oxidative modifications of PSII proteins. In this study, oxidative modifications of the D1 and D2 proteins by the superoxide anion (O2 •-) and the hydroxyl (HO•) radicals were studied in WT and a tocopherol cyclase (vte1) mutant, which is deficient in the lipid-soluble antioxidant α-tocopherol. In the absence of this antioxidant, high-resolution tandem mass spectrometry was used to identify oxidation of D1:130E to hydroxyglutamic acid by O2 •- at the PheoD1 site. Additionally, D1:246Y was modified to either tyrosine hydroperoxide or dihydroxyphenylalanine by O2 •- and HO•, respectively, in the vicinity of the nonheme iron. We propose that α-tocopherol is localized near PheoD1 and the nonheme iron, with its chromanol head exposed to the lipid-water interface. This helps to prevent oxidative modification of the amino acid's hydrogen that is bonded to PheoD1 and the nonheme iron (via bicarbonate), and thus protects electron transport in PSII from ROS damage.
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4
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Kale R, Sallans L, Frankel LK, Bricker TM. Natively oxidized amino acid residues in the spinach PS I-LHC I supercomplex. PHOTOSYNTHESIS RESEARCH 2020; 143:263-273. [PMID: 31894498 DOI: 10.1007/s11120-019-00698-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 12/05/2019] [Indexed: 06/10/2023]
Abstract
Reactive oxygen species (ROS) production is an unavoidable byproduct of electron transport under aerobic conditions. Photosystem II (PS II), the cytochrome b6/f complex and Photosystem I (PS I) are all demonstrated sources of ROS. It has been proposed that PS I produces substantial levels of a variety of ROS including O2.-, 1O2, H2O2 and, possibly, •OH; however, the site(s) of ROS production within PS I has been the subject of significant debate. We hypothesize that amino acid residues close to the sites of ROS generation will be more susceptible to oxidative modification than distant residues. In this study, we have identified oxidized amino acid residues in spinach PS I which was isolated from field-grown spinach. The modified residues were identified by high-resolution tandem mass spectrometry. As expected, many of the modified residues lie on the surface of the complex. However, a well-defined group of oxidized residues, both buried and surface-exposed, lead from the chl a' of P700 to the surface of PS I. These residues (PsaB: 609F, 611E, 617M, 619W, 620L, and PsaF: 139L, 142A,143D) may identify a preferred route for ROS, probably 1O2, to egress the complex from the vicinity of P700. Additionally, two buried residues located in close proximity to A1B (PsaB:712H and 714S) were modified, which appears consistent with A1B being a source of O2.-. Surprisingly, no oxidatively modified residues were identified in close proximity to the 4Fe-FS clusters FX, FA or FB. These cofactors had been identified as principal targets for ROS damage in the photosystem. Finally, a large number of residues located in the hydrophobic cores of Lhca1-Lhca4 are oxidatively modified. These appear to be the result of 1O2 production by the distal antennae for the photosystem.
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Affiliation(s)
- Ravindra Kale
- Department of Biological Sciences, Biochemistry and Molecular Biology Section, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Larry Sallans
- The Rieveschl Laboratories for Mass Spectrometry, Department of Chemistry, University of Cincinnati, Cincinnati, OH, 45221, USA
| | - Laurie K Frankel
- Department of Biological Sciences, Biochemistry and Molecular Biology Section, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Terry M Bricker
- Department of Biological Sciences, Biochemistry and Molecular Biology Section, Louisiana State University, Baton Rouge, LA, 70803, USA.
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5
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Taylor RM, Sallans L, Frankel LK, Bricker TM. Natively oxidized amino acid residues in the spinach cytochrome b 6 f complex. PHOTOSYNTHESIS RESEARCH 2018; 137:141-151. [PMID: 29380263 DOI: 10.1007/s11120-018-0485-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 01/18/2018] [Indexed: 05/25/2023]
Abstract
The cytochrome b 6 f complex of oxygenic photosynthesis produces substantial levels of reactive oxygen species (ROS). It has been observed that the ROS production rate by b 6 f is 10-20 fold higher than that observed for the analogous respiratory cytochrome bc1 complex. The types of ROS produced (O2•-, 1O2, and, possibly, H2O2) and the site(s) of ROS production within the b 6 f complex have been the subject of some debate. Proposed sources of ROS have included the heme b p , PQ p•- (possible sources for O2•-), the Rieske iron-sulfur cluster (possible source of O2•- and/or 1O2), Chl a (possible source of 1O2), and heme c n (possible source of O2•- and/or H2O2). Our working hypothesis is that amino acid residues proximal to the ROS production sites will be more susceptible to oxidative modification than distant residues. In the current study, we have identified natively oxidized amino acid residues in the subunits of the spinach cytochrome b 6 f complex. The oxidized residues were identified by tandem mass spectrometry using the MassMatrix Program. Our results indicate that numerous residues, principally localized near p-side cofactors and Chl a, were oxidatively modified. We hypothesize that these sites are sources for ROS generation in the spinach cytochrome b 6 f complex.
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Affiliation(s)
- Ryan M Taylor
- Department of Biological Sciences, Biochemistry and Molecular Biology Section, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Larry Sallans
- The Rieveschl Laboratories for Mass Spectrometry, Department of Chemistry, University of Cincinnati, Cincinnati, OH, 45221, USA
| | - Laurie K Frankel
- Department of Biological Sciences, Biochemistry and Molecular Biology Section, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Terry M Bricker
- Department of Biological Sciences, Biochemistry and Molecular Biology Section, Louisiana State University, Baton Rouge, LA, 70803, USA.
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6
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Muller L, Fornecker L, Chion M, Van Dorsselaer A, Cianférani S, Rabilloud T, Carapito C. Extended investigation of tube-gel sample preparation: a versatile and simple choice for high throughput quantitative proteomics. Sci Rep 2018; 8:8260. [PMID: 29844437 PMCID: PMC5974325 DOI: 10.1038/s41598-018-26600-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 05/10/2018] [Indexed: 11/09/2022] Open
Abstract
Sample preparation for quantitative proteomics is a crucial step to ensure the repeatability and the accuracy of the results. However, there is no universal method compatible with the wide variety of protein extraction buffers currently used. We have recently demonstrated the compatibility of tube-gel with SDS-based buffers and its efficiency for label-free quantitative proteomics by comparing it to stacking gel and liquid digestion. Here, we investigated the compatibility of tube-gel with alternatives to SDS-based buffers allowing notably the extraction of proteins in various pH conditions. We also explored the use of photopolymerization to extend the number of possibilities, as it is compatible with a wide range of pH and is non-oxidative. To achieve this goal, we compared six extraction buffers in combination with two polymerization conditions to further optimize the tube-gel protocol and evaluate its versatility. Identification and quantitative results demonstrated the compatibility of tube-gel with all tested conditions by overall raising quite comparable results. In conclusion, tube-gel is a versatile and simple sample preparation method for large-scale quantitative proteomics applications. Complete datasets are available via ProteomeXchange with identifier PXD008656.
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Affiliation(s)
- Leslie Muller
- Laboratoire de Spectrométrie de Masse Bio-Organique (LSMBO), IPHC, UMR 7178, Université de Strasbourg, CNRS, 25 rue Becquerel, 67087, Strasbourg, France
| | - Luc Fornecker
- Laboratoire de Spectrométrie de Masse Bio-Organique (LSMBO), IPHC, UMR 7178, Université de Strasbourg, CNRS, 25 rue Becquerel, 67087, Strasbourg, France
| | - Marie Chion
- Laboratoire de Spectrométrie de Masse Bio-Organique (LSMBO), IPHC, UMR 7178, Université de Strasbourg, CNRS, 25 rue Becquerel, 67087, Strasbourg, France
| | - Alain Van Dorsselaer
- Laboratoire de Spectrométrie de Masse Bio-Organique (LSMBO), IPHC, UMR 7178, Université de Strasbourg, CNRS, 25 rue Becquerel, 67087, Strasbourg, France
| | - Sarah Cianférani
- Laboratoire de Spectrométrie de Masse Bio-Organique (LSMBO), IPHC, UMR 7178, Université de Strasbourg, CNRS, 25 rue Becquerel, 67087, Strasbourg, France
| | - Thierry Rabilloud
- Laboratoire de Chimie et Biologie des Métaux, UMR CNRS-CEA-UGA 5249, iRTSV/LCBM, CEA Grenoble, Grenoble, France
| | - Christine Carapito
- Laboratoire de Spectrométrie de Masse Bio-Organique (LSMBO), IPHC, UMR 7178, Université de Strasbourg, CNRS, 25 rue Becquerel, 67087, Strasbourg, France.
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7
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Amino acid oxidation of the D1 and D2 proteins by oxygen radicals during photoinhibition of Photosystem II. Proc Natl Acad Sci U S A 2017; 114:2988-2993. [PMID: 28265052 DOI: 10.1073/pnas.1618922114] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The Photosystem II reaction center is vulnerable to photoinhibition. The D1 and D2 proteins, lying at the core of the photosystem, are susceptible to oxidative modification by reactive oxygen species that are formed by the photosystem during illumination. Using spin probes and EPR spectroscopy, we have determined that both O2•- and HO• are involved in the photoinhibitory process. Using tandem mass spectroscopy, we have identified a number of oxidatively modified D1 and D2 residues. Our analysis indicates that these oxidative modifications are associated with formation of HO• at both the Mn4O5Ca cluster and the nonheme iron. Additionally, O2•- appears to be formed by the reduction of O2 at either PheoD1 or QA Early oxidation of D1:332H, which is coordinated with the Mn1 of the Mn4O5Ca cluster, appears to initiate a cascade of oxidative events that lead to the oxidative modification of numerous residues in the C termini of the D1 and D2 proteins on the donor side of the photosystem. Oxidation of D2:244Y, which is a bicarbonate ligand for the nonheme iron, induces the propagation of oxidative reactions in residues of the D-de loop of the D2 protein on the electron acceptor side of the photosystem. Finally, D1:130E and D2:246M are oxidatively modified by O2•- formed by the reduction of O2 either by PheoD1•- or QA•- The identification of specific amino acid residues oxidized by reactive oxygen species provides insights into the mechanism of damage to the D1 and D2 proteins under light stress.
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8
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Mummadisetti MP, Frankel LK, Bellamy HD, Sallans L, Goettert JS, Brylinski M, Bricker TM. Use of Protein Cross-Linking and Radiolytic Labeling To Elucidate the Structure of PsbO within Higher-Plant Photosystem II. Biochemistry 2016; 55:3204-13. [PMID: 27203407 DOI: 10.1021/acs.biochem.6b00365] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
We have used protein cross-linking with the zero-length cross-linker 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, and radiolytic footprinting coupled with high-resolution tandem mass spectrometry, to examine the structure of higher-plant PsbO when it is bound to Photosystem II. Twenty intramolecular cross-linked residue pairs were identified. On the basis of this cross-linking data, spinach PsbO was modeled using the Thermosynechococcus vulcanus PsbO structure as a template, with the cross-linking distance constraints incorporated using the MODELLER program. Our model of higher-plant PsbO identifies several differences between the spinach and cyanobacterial proteins. The N-terminal region is particularly interesting, as this region has been suggested to be important for oxygen evolution and for the specific binding of PsbO to Photosystem II. Additionally, using radiolytic mapping, we have identified regions on spinach PsbO that are shielded from the bulk solvent. These domains may represent regions on PsbO that interact with other components, as yet unidentified, of the photosystem.
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Affiliation(s)
- Manjula P Mummadisetti
- Division of Biochemistry and Molecular Biology, Department of Biological Sciences, Louisiana State University , Baton Rouge, Louisiana 70803, United States
| | - Laurie K Frankel
- Division of Biochemistry and Molecular Biology, Department of Biological Sciences, Louisiana State University , Baton Rouge, Louisiana 70803, United States
| | - Henry D Bellamy
- The J. Bennett Johnston, Sr. Center for Advanced Microstructures & Devices, Louisiana State University , Baton Rouge, Louisiana 70806, United States
| | - Larry Sallans
- The Rieveschl Laboratories for Mass Spectrometry, Department of Chemistry, University of Cincinnati , Cincinnati, Ohio 45221, United States
| | - Jost S Goettert
- The J. Bennett Johnston, Sr. Center for Advanced Microstructures & Devices, Louisiana State University , Baton Rouge, Louisiana 70806, United States
| | - Michal Brylinski
- Division of Biochemistry and Molecular Biology, Department of Biological Sciences, Louisiana State University , Baton Rouge, Louisiana 70803, United States
| | - Terry M Bricker
- Division of Biochemistry and Molecular Biology, Department of Biological Sciences, Louisiana State University , Baton Rouge, Louisiana 70803, United States
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9
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Frankel LK, Sallans L, Bellamy H, Goettert JS, Limbach PA, Bricker TM. Radiolytic mapping of solvent-contact surfaces in Photosystem II of higher plants: experimental identification of putative water channels within the photosystem. J Biol Chem 2013; 288:23565-72. [PMID: 23814046 DOI: 10.1074/jbc.m113.487033] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Photosystem II uses water as an enzymatic substrate. It has been hypothesized that this water is vectored to the active site for water oxidation via water channels that lead from the surface of the protein complex to the Mn4O5Ca metal cluster. The radiolysis of water by synchrotron radiation produces amino acid residue-modifying OH(•) and is a powerful technique to identify regions of proteins that are in contact with water. In this study, we have used this technique to oxidatively modify buried amino acid residues in higher plant Photosystem II membranes. Fourier transform ion cyclotron resonance mass spectrometry was then used to identify these oxidized amino acid residues that were located in several core Photosystem II subunits (D1, D2, CP43, and CP47). While, as expected, the majority of the identified oxidized residues (≈75%) are located on the solvent-exposed surface of the complex, a number of buried residues on these proteins were also modified. These residues form groups which appear to lead from the surface of the complex to the Mn4O5Ca cluster. These residues may be in contact with putative water channels in the photosystem. These results are discussed within the context of a number of largely computational studies that have identified putative water channels in Photosystem II.
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Affiliation(s)
- Laurie K Frankel
- Department of Biological Sciences, Division of Biochemistry and Molecular Biology, Louisiana State University, Baton Rouge, Louisiana 70803, USA
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10
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Frankel LK, Sallans L, Limbach PA, Bricker TM. Oxidized amino acid residues in the vicinity of Q(A) and Pheo(D1) of the photosystem II reaction center: putative generation sites of reducing-side reactive oxygen species. PLoS One 2013; 8:e58042. [PMID: 23469138 PMCID: PMC3585169 DOI: 10.1371/journal.pone.0058042] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Accepted: 01/30/2013] [Indexed: 02/04/2023] Open
Abstract
Under a variety of stress conditions, Photosystem II produces reactive oxygen species on both the reducing and oxidizing sides of the photosystem. A number of different sites including the Mn4O5Ca cluster, P680, PheoD1, QA, QB and cytochrome b559 have been hypothesized to produce reactive oxygen species in the photosystem. In this communication using Fourier-transform ion cyclotron resonance mass spectrometry we have identified several residues on the D1 and D2 proteins from spinach which are oxidatively modified and in close proximity to QA (D1 residues 239F, 241Q, 242E and the D2 residues 238P, 239T, 242E and 247M) and PheoD1 (D1 residues 130E, 133L and 135F). These residues may be associated with reactive oxygen species exit pathways located on the reducing side of the photosystem, and their modification may indicate that both QA and PheoD1 are sources of reactive oxygen species on the reducing side of Photosystem II.
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Affiliation(s)
- Laurie K. Frankel
- Department of Biological Sciences, Division of Biochemistry and Molecular Biology, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Larry Sallans
- The Rieveschl Laboratories for Mass Spectrometry, Department of Chemistry, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Patrick A. Limbach
- The Rieveschl Laboratories for Mass Spectrometry, Department of Chemistry, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Terry M. Bricker
- Department of Biological Sciences, Division of Biochemistry and Molecular Biology, Louisiana State University, Baton Rouge, Louisiana, United States of America
- * E-mail:
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11
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Frankel LK, Sallans L, Limbach PA, Bricker TM. Identification of oxidized amino acid residues in the vicinity of the Mn(4)CaO(5) cluster of Photosystem II: implications for the identification of oxygen channels within the Photosystem. Biochemistry 2012; 51:6371-7. [PMID: 22827410 DOI: 10.1021/bi300650n] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
As a light-driven water-plastoquinone oxidoreductase, Photosystem II produces molecular oxygen as an enzymatic product. Additionally, under a variety of stress conditions, reactive oxygen species are produced at or near the active site for oxygen evolution. In this study, Fourier-transform ion cyclotron resonance mass spectrometry was used to identify oxidized amino acid residues located in several core Photosystem II proteins (D1, D2, CP43, and CP47) isolated from spinach Photosystem II membranes. While the majority of these oxidized residues (81%) are located on the oxygenated solvent-exposed surface of the complex, several residues on the CP43 protein ((354)E, (355)T, (356)M, and (357)R) which are in close proximity (<15 Å) to the Mn(4)CaO(5) active site are also modified. These residues appear to be associated with putative oxygen/reactive oxygen species exit channel(s) in the photosystem. These results are discussed within the context of a number of computational studies which have identified putative oxygen channels within the photosystem.
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Affiliation(s)
- Laurie K Frankel
- Department of Biological Sciences, Division of Biochemistry and Molecular Biology, Louisiana State University, Baton Rouge, LA 70803, USA
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12
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Variations on a theme: Changes to electrophoretic separations that can make a difference. J Proteomics 2010; 73:1562-72. [DOI: 10.1016/j.jprot.2010.04.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Revised: 04/01/2010] [Accepted: 04/03/2010] [Indexed: 11/19/2022]
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13
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Patras G, Qiao GG, Solomon DH. On the mechanism of background silver staining during sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Electrophoresis 1999; 20:2039-45. [PMID: 10451112 DOI: 10.1002/(sici)1522-2683(19990701)20:10<2039::aid-elps2039>3.0.co;2-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A novel experimental procedure to study the factors that contribute to background silver staining in sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) is described. A mechanism is proposed for background silver staining, which was found to result primarily from the redox initiator system using ammonium persulphate (APS) and an amine such as N,N,N',N'-tetramethylethylenediamine (TEMED).
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Affiliation(s)
- G Patras
- Department of Chemical Engineering, The University of Melbourne, Parkville, Australia
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14
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MIGNON B, SWINNEN M, BOUCHARA JP, HOFINGER M, NIKKELS A, PIERARD G, GERDAY CH, LOSSON B. Purification and characterization of a 315 kDa keratinolytic subtilisin-like serine protease from Microsporum canis and evidence of its secretion in naturally infected cats. Med Mycol 1998. [DOI: 10.1046/j.1365-280x.1998.00179.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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15
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Mignon B, Swinnen M, Bouchara J, Hofinger M, Nikkels A, Pierard G, Gerday C, Losson B. Purification and characterization of a 315 kDa keratinolytic subtilisin-like serine protease fromMicrosporum canisand evidence of its secretion in naturally infected cats. Med Mycol 1998. [DOI: 10.1080/02681219880000631] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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16
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Righetti PG, Gelfi C. Electrophoresis gel media: the state of the art. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 1997; 699:63-75. [PMID: 9392368 DOI: 10.1016/s0378-4347(96)00207-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Some unique events have occurred in the last few years which might revolutionize the field of polyacrylamide gel electrophoresis. While it was widely recognized that such matrices could normally be cast with a small pore size distribution, typically of the order of a few nanometers diameter (for protein sieving), recent developments suggest that "macroporous" gels could also be produced in the domain of polyacrylamides. If constraints to chain motion are imposed during gel polymerization, large-pore structures can be grown. Such constraints can originate either from low temperatures or from the presence of preformed polymers in the gelling solution; in both cases, the growing chains are forced to "laterally aggregate" via inter-chain hydrogen bond formation. Upon consumption of pendant double bonds, such bundles are frozen in the three-dimensional space by permanent cross-links. As an additional development, a novel photopolymerization system is described, comprising a cationic dye (methylene blue) and a redox couple (sodium toluene sulfinate, a reducer, and diphenyliodonium chloride, a mild oxidizer). Methylene blue catalysis is characterized by a unique efficiency, ensuring >96% conversion of monomers, even in hydro-organic solvents and in the presence of surfactants, which normally quench or completely inhibit the persulphate-driven reaction. In addition, methylene blue-sustained photopolymerization can be operated in the entire pH 3-10 interval, where most other systems fail. Perhaps the most striking novelty in the field is the appearance of a novel monomer (N-acryloylaminopropanol, AAP) coupling a high hydrophilicity with a unique resistance to alkaline hydrolysis. Given the fact that a poly(AAP) matrix is 500 times more stable than a poly(acrylamide) gel, while being twice as hydrophilic, it is anticipated that this novel chemistry will have no difficulties in replacing the old electrophoretic anticonvective media. The review ends with a glimpse at novel sieving media in capillary zone electrophoresis: polymer networks. Such media, by providing an almost infinite range of pore sizes, due to the absence of a rigid support, allow sieving mechanisms to be operative over a wide interval of particle sizes, even up to genomic DNA. Viscous solutions of polymer networks, made with the novel poly(AAP) chemistry, allow repeated use of the same separation column, well above 50 injections. Silica-bound poly(AAP) chains provide effective quenching of electroosmosis and >200 analyses by isoelectric focusing.
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Affiliation(s)
- P G Righetti
- Department of Agricultural and Industrial Biotechnologies, University of Verona, Italy
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Gillespie PG, Gillespie SK. Improved electrophoresis and transfer of picogram amounts of protein with hemoglobin. Anal Biochem 1997; 246:239-45. [PMID: 9073362 DOI: 10.1006/abio.1997.2019] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
During electrophoresis and electroblotting to transfer membranes, picogram amounts of protein can react irreversibly with the polyacrylamide matrix, preventing complete electrophoresis and efficient electroblotting. Bovine hemoglobin, but not other potential carrier proteins, mitigates this protein loss by migrating with or ahead of other proteins and scavenging reactive groups. Inclusion of 5 micrograms of hemoglobin in sample wells increases by 4-fold the amount of a radiolabeled test protein, myosin I beta, found at its appropriate 120-kDa position in sodium dodecyl sulfate-polyacrylamide gels. For electroblotting, incubating the gel with 0.25 mg/ml hemoglobin prior to transfer improves mobilization of picogram amounts of radiolabeled myosin I beta out of the gel by about 6-fold. For picogram amounts of proteins, therefore, approximately 20-fold more protein transfers to a blotting membrane when hemoglobin is used during both electrophoresis and transfer. This effect is general: transfer of radiolabeled Drosophila embryo proteins is improved dramatically by including hemoglobin in the pretransfer incubation solution. We suggest that electroblot-based detection of small amounts of protein, particularly when in the absence of other potential carrier proteins, can be improved substantially by using hemoglobin.
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Affiliation(s)
- P G Gillespie
- Department of Physiology, Johns Hopkins University, Baltimore, Maryland 21205, USA
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