1
|
Rapid Scan Electron Paramagnetic Resonance Spectroscopy Is a Suitable Tool to Study Intermolecular Interactions of Intrinsically Disordered Protein. BIOLOGY 2023; 12:biology12010079. [PMID: 36671771 PMCID: PMC9856040 DOI: 10.3390/biology12010079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 12/21/2022] [Accepted: 12/22/2022] [Indexed: 01/06/2023]
Abstract
Intrinsically disordered proteins (IDPs) are involved in most crucial cellular processes. However, they lack a well-defined fold hampering the investigation of their structural ensemble and interactions. Suitable biophysical methods able to manage their inherent flexibility and broad conformational ensemble are scarce. Here, we used rapid scan (RS) electron paramagnetic resonance (EPR) spectroscopy to study the intermolecular interactions of the IDP α-synuclein (aS). aS aggregation and fibril deposition is the hallmark of Parkinson's disease, and specific point mutations, among them A30P and A53T, were linked to the early onset of the disease. To understand the pathological processes, research intensively investigates aS aggregation kinetics, which was reported to be accelerated in the presence of ethanol. Conventional techniques fail to capture these fast processes due to their limited time resolution and, thus, lose kinetic information. We have demonstrated that RS EPR spectroscopy is suitable for studying aS aggregation by resolving underlying kinetics and highlighting differences in fibrillization behavior. RS EPR spectroscopy outperforms traditional EPR methods in terms of sensitivity by a factor of 5 in our case while significantly reducing data acquisition time. Thus, we were able to sample short time intervals capturing single events taking place during the aggregation process. Further studies will therefore be able to shed light on biological processes proceeding on fast time scales.
Collapse
|
2
|
Bognár B, Úr G, Sár C, Hankovszky OH, Hideg K, Kálai T. Synthesis and Application of Stable Nitroxide Free Radicals Fused with Carbocycles and Heterocycles. CURR ORG CHEM 2019. [DOI: 10.2174/1385272823666190318163321] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Stable nitroxide free radicals have traditionally been associated with 2,2,6,6-
tetramethylpiperidine-1-oxyl (TEMPO) or its 4-substituted derivatives as relatively inexpensive
and readily accessible compounds with limited possibilities for further chemical
modification. Over the past two decades, there has been a resurgence of interest in stable
free radicals with proper functionalization tuned for various applications. The objective of
this review is to present recent results with synthetic methodologies to achieve stable nitroxide
free radicals fused with aromatic carbocycles and heterocycles. There are two
main approaches for accessing stable nitroxide free radicals fused with arenes, e.g., isoindoline-
like nitroxides: further functionalization and oxidation of phthalimide or inventive
functionalization of pyrroline nitroxide key compounds. The latter also offers the constructions
of versatile heterocyclic scaffolds (furan, pyrrole, thiophene, 1,2-thiazole, selenophene, pyrazole,
pyrimidine, pyridine, pyridazine, 1,5-benzothiazepine) that are fused with pyrroline or tetrahydropyridine nitroxide
rings. The possible applications of these new stable nitroxide free radicals, such as covalent spin labels
and noncovalent spin probes of proteins and nucleic acids, profluorescent probes, building blocks for construction
of dual active drugs and electroactive materials, and substances for controlled free radical polymerization,
are discussed.
Collapse
Affiliation(s)
- Balázs Bognár
- Institute of Organic and Medicinal Chemistry, Medical School, University of Pecs, Szigeti st. 12, H-7624 Pecs, Hungary
| | - Györgyi Úr
- Institute of Organic and Medicinal Chemistry, Medical School, University of Pecs, Szigeti st. 12, H-7624 Pecs, Hungary
| | - Cecília Sár
- Institute of Organic and Medicinal Chemistry, Medical School, University of Pecs, Szigeti st. 12, H-7624 Pecs, Hungary
| | - Olga H. Hankovszky
- Institute of Organic and Medicinal Chemistry, Medical School, University of Pecs, Szigeti st. 12, H-7624 Pecs, Hungary
| | - Kálmán Hideg
- Institute of Organic and Medicinal Chemistry, Medical School, University of Pecs, Szigeti st. 12, H-7624 Pecs, Hungary
| | - Tamás Kálai
- Institute of Organic and Medicinal Chemistry, Medical School, University of Pecs, Szigeti st. 12, H-7624 Pecs, Hungary
| |
Collapse
|
3
|
New limits of sensitivity of site-directed spin labeling electron paramagnetic resonance for membrane proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:841-853. [DOI: 10.1016/j.bbamem.2017.12.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 11/27/2017] [Accepted: 12/09/2017] [Indexed: 01/27/2023]
|
4
|
Eaton SS, Shi Y, Woodcock L, Buchanan LA, McPeak J, Quine RW, Rinard GA, Epel B, Halpern HJ, Eaton GR. Rapid-scan EPR imaging. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 280:140-148. [PMID: 28579099 PMCID: PMC5523658 DOI: 10.1016/j.jmr.2017.02.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 02/17/2017] [Accepted: 02/18/2017] [Indexed: 05/12/2023]
Abstract
In rapid-scan EPR the magnetic field or frequency is repeatedly scanned through the spectrum at rates that are much faster than in conventional continuous wave EPR. The signal is directly-detected with a mixer at the source frequency. Rapid-scan EPR is particularly advantageous when the scan rate through resonance is fast relative to electron spin relaxation rates. In such scans, there may be oscillations on the trailing edge of the spectrum. These oscillations can be removed by mathematical deconvolution to recover the slow-scan absorption spectrum. In cases of inhomogeneous broadening, the oscillations may interfere destructively to the extent that they are not visible. The deconvolution can be used even when it is not required, so spectra can be obtained in which some portions of the spectrum are in the rapid-scan regime and some are not. The technology developed for rapid-scan EPR can be applied generally so long as spectra are obtained in the linear response region. The detection of the full spectrum in each scan, the ability to use higher microwave power without saturation, and the noise filtering inherent in coherent averaging results in substantial improvement in signal-to-noise relative to conventional continuous wave spectroscopy, which is particularly advantageous for low-frequency EPR imaging. This overview describes the principles of rapid-scan EPR and the hardware used to generate the spectra. Examples are provided of its application to imaging of nitroxide radicals, diradicals, and spin-trapped radicals at a Larmor frequency of ca. 250MHz.
Collapse
Affiliation(s)
- Sandra S Eaton
- Department of Chemistry and Biochemistry and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80210, United States
| | - Yilin Shi
- Department of Chemistry and Biochemistry and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80210, United States
| | - Lukas Woodcock
- Department of Chemistry and Biochemistry and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80210, United States
| | - Laura A Buchanan
- Department of Chemistry and Biochemistry and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80210, United States
| | - Joseph McPeak
- Department of Chemistry and Biochemistry and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80210, United States
| | - Richard W Quine
- School of Engineering and Computer Science and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80210, United States
| | - George A Rinard
- School of Engineering and Computer Science and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80210, United States
| | - Boris Epel
- Department of Radiation and Cellular Oncology and Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, United States
| | - Howard J Halpern
- Department of Radiation and Cellular Oncology and Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, United States
| | - Gareth R Eaton
- Department of Chemistry and Biochemistry and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80210, United States.
| |
Collapse
|
5
|
Detection of Reactive Oxygen and Nitrogen Species by Electron Paramagnetic Resonance (EPR) Technique. Molecules 2017; 22:molecules22010181. [PMID: 28117726 PMCID: PMC6155876 DOI: 10.3390/molecules22010181] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 01/05/2017] [Accepted: 01/17/2017] [Indexed: 01/15/2023] Open
Abstract
During the last decade there has been growing interest in physical-chemical oxidation processes and the behavior of free radicals in living systems. Radicals are known as intermediate species in a variety of biochemical reactions. Numerous techniques, assays and biomarkers have been used to measure reactive oxygen and nitrogen species (ROS and RNS), and to examine oxidative stress. However, many of these assays are not entirely satisfactory or are used inappropriately. The purpose of this chapter is to review current EPR (Electron Paramagnetic Resonance) spectroscopy methods for measuring ROS, RNS, and their secondary products, and to discuss the strengths and limitations of specific methodological approaches.
Collapse
|
6
|
Use of spin traps to detect superoxide production in living cells by electron paramagnetic resonance (EPR) spectroscopy. Methods 2016; 109:31-43. [DOI: 10.1016/j.ymeth.2016.05.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 05/04/2016] [Accepted: 05/05/2016] [Indexed: 01/23/2023] Open
|