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Agarwala P, Ghosh A, Hazarika P, Acharjee D, Ghosh S, Rout D, Sasmal DK. Unraveling the Interaction of Diflunisal with Cyclodextrin and Lysozyme by Fluorescence Spectroscopy. J Phys Chem B 2023; 127:9710-9723. [PMID: 37917720 DOI: 10.1021/acs.jpcb.3c04295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2023]
Abstract
Understanding the interaction between the drug:carrier complex and protein is essential for the development of a new drug-delivery system. However, the majority of reports are based on an understanding of interactions between the drug and protein. Here, we present our findings on the interaction of the anti-inflammatory drug diflunisal with the drug carrier cyclodextrin (CD) and the protein lysozyme, utilizing steady-state and time-resolved fluorescence spectroscopy. Our findings reveal a different pattern of molecular interaction between the inclusion complex of β-CD (β-CD) or hydroxypropyl-β-CD (HP-β-CD) (as the host) and diflunisal (as the guest) in the presence of protein lysozyme. The quantum yield for the 1:2 guest:host complex is twice that of the 1:1 guest:host complex, indicating a more stable hydrophobic microenvironment created in the 1:2 complex. Consequently, the nonradiative decay pathway is significantly reduced. The interaction is characterized by ultrafast solvation dynamics and time-resolved fluorescence resonance energy transfer. The solvation dynamics of the lysozyme becomes 10% faster under the condition of binding with the drug, indicating a negligible change in the polar environment after binding. In addition, the fluorescence lifetime of diflunisal (acceptor) is increased by 50% in the presence of the lysozyme (donor), which indicates that the drug molecule is bound to the binding pocket on the surface of the protein, and the average distance between active tryptophan in the hydrophobic region and diflunisal is calculated to be approximately 50 Å. Excitation and emission matrix spectroscopy reveals that the tryptophan emission increases 3-5 times in the presence of both diflunisal and CD. This indicates that the tryptophan of lysozyme may be present in a more hydrophobic environment in the presence of both diflunisal and CD. Our observations on the interaction of diflunisal with β-CD and lysozyme are well supported by molecular dynamics simulation. Results from this study may have an impact on the development of a better drug-delivery system in the future. It also reveals a fundamental molecular mechanism of interaction of the drug-carrier complex with the protein.
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Affiliation(s)
- Pratibha Agarwala
- Department of Chemistry, Indian Institute of Technology Jodhpur, Jodhpur, Rajasthan 342037, India
| | - Arabinda Ghosh
- Department of Computational Biology and Biotechnology, Mahapurusha Srimanta Sankaradeva Viswavidyalaya, Guwahati Unit, Guwahati, Assam 781032, India
| | - Priyanka Hazarika
- Department of Chemistry, Indian Institute of Technology Jodhpur, Jodhpur, Rajasthan 342037, India
| | - Debopam Acharjee
- School of Chemical Sciences, National Institute of Science Education and Research, An OCC of Homi Bhabha National Institute (HBNI), Khurda, Odisha 752050, India
| | - Shirsendu Ghosh
- Department of Chemistry, Gandhi Institute of Technology and Management (GITAM), Hyderabad Campus, Hyderabad 502329, India
| | - Debasish Rout
- Department of Chemistry, Indian Institute of Technology Jodhpur, Jodhpur, Rajasthan 342037, India
| | - Dibyendu K Sasmal
- Department of Chemistry, Indian Institute of Technology Jodhpur, Jodhpur, Rajasthan 342037, India
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Agarwala P, Bera T, Sasmal DK. Molecular Mechanism of Interaction of Curcumin with BSA, Surfactants and Live E. Coli Cell Membrane Revealed by Fluorescence Spectroscopy and Confocal Microscopy. Chemphyschem 2022; 23:e202200265. [DOI: 10.1002/cphc.202200265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 05/20/2022] [Indexed: 11/08/2022]
Affiliation(s)
- Pratibha Agarwala
- Indian Institute of Technology Rajasthan: Indian Institute of Technology Jodhpur Department of chemistry 342037 Jodhpur INDIA
| | - Turban Bera
- Indian Institute of Technology Jodhpur Department of chemistry INDIA
| | - Dibyendu Kumar Sasmal
- Indian Institute of Technology Jodhpur Chemistry NH65, Surpura bypass roadkarwar 342037 Jodhpur INDIA
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Diffracted X-ray Tracking Method for Measuring Intramolecular Dynamics of Membrane Proteins. Int J Mol Sci 2022; 23:ijms23042343. [PMID: 35216461 PMCID: PMC8880040 DOI: 10.3390/ijms23042343] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 02/14/2022] [Accepted: 02/17/2022] [Indexed: 02/06/2023] Open
Abstract
Membrane proteins change their conformations in response to chemical and physical stimuli and transmit extracellular signals inside cells. Several approaches have been developed for solving the structures of proteins. However, few techniques can monitor real-time protein dynamics. The diffracted X-ray tracking method (DXT) is an X-ray-based single-molecule technique that monitors the internal motion of biomolecules in an aqueous solution. DXT analyzes trajectories of Laue spots generated from the attached gold nanocrystals with a two-dimensional axis by tilting (θ) and twisting (χ). Furthermore, high-intensity X-rays from synchrotron radiation facilities enable measurements with microsecond-timescale and picometer-spatial-scale intramolecular information. The technique has been applied to various membrane proteins due to its superior spatiotemporal resolution. In this review, we introduce basic principles of DXT, reviewing its recent and extended applications to membrane proteins and living cells, respectively.
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4
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Raghuraman H, Chatterjee S, Das A. Site-Directed Fluorescence Approaches for Dynamic Structural Biology of Membrane Peptides and Proteins. Front Mol Biosci 2019; 6:96. [PMID: 31608290 PMCID: PMC6774292 DOI: 10.3389/fmolb.2019.00096] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 09/11/2019] [Indexed: 12/31/2022] Open
Abstract
Membrane proteins mediate a number of cellular functions and are associated with several diseases and also play a crucial role in pathogenicity. Due to their importance in cellular structure and function, they are important drug targets for ~60% of drugs available in the market. Despite the technological advancement and recent successful outcomes in determining the high-resolution structural snapshot of membrane proteins, the mechanistic details underlining the complex functionalities of membrane proteins is least understood. This is largely due to lack of structural dynamics information pertaining to different functional states of membrane proteins in a membrane environment. Fluorescence spectroscopy is a widely used technique in the analysis of functionally-relevant structure and dynamics of membrane protein. This review is focused on various site-directed fluorescence (SDFL) approaches and their applications to explore structural information, conformational changes, hydration dynamics, and lipid-protein interactions of important classes of membrane proteins that include the pore-forming peptides/proteins, ion channels/transporters and G-protein coupled receptors.
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Affiliation(s)
- H. Raghuraman
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Homi Bhabha National Institute, Kolkata, India
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5
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TCR-pMHC bond conformation controls TCR ligand discrimination. Cell Mol Immunol 2019; 17:203-217. [PMID: 31530899 PMCID: PMC7052167 DOI: 10.1038/s41423-019-0273-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Accepted: 08/07/2019] [Indexed: 11/15/2022] Open
Abstract
A major unanswered question is how a TCR discriminates between foreign and self-peptides presented on the APC surface. Here, we used in situ fluorescence resonance energy transfer (FRET) to measure the distances of single TCR–pMHC bonds and the conformations of individual TCR–CD3ζ receptors at the membranes of live primary T cells. We found that a TCR discriminates between closely related peptides by forming single TCR–pMHC bonds with different conformations, and the most potent pMHC forms the shortest bond. The bond conformation is an intrinsic property that is independent of the binding affinity and kinetics, TCR microcluster formation, and CD4 binding. The bond conformation dictates the degree of CD3ζ dissociation from the inner leaflet of the plasma membrane via a positive calcium signaling feedback loop to precisely control the accessibility of CD3ζ ITAMs for phosphorylation. Our data revealed the mechanism by which a TCR deciphers the structural differences among peptides via the TCR–pMHC bond conformation.
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Chatterjee S, Dutta C, Carrejo NC, Landes CF. Mechanistic Understanding of the Phosphorylation-Induced Conformational Rigidity at the AMPA Receptor C-terminal Domain. ACS OMEGA 2019; 4:14211-14218. [PMID: 31508543 PMCID: PMC6732983 DOI: 10.1021/acsomega.9b01384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 08/06/2019] [Indexed: 06/10/2023]
Abstract
Phosphorylation at the intracellular C-terminal domain (CTD) of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors induces conformational rigidity. Such intracellular alterations to the AMPA receptor influence its functional responses, which are involved in multiple synaptic processes and neuronal signaling. The structure of the CTD still remains unresolved, which poses challenges toward providing a mechanism for the process of phosphorylation and deciphering the role of each phosphorylation step in causing the resultant conformational behavior. Herein, we utilize smFRET spectroscopy to understand the mechanism of phosphorylation, with the help of strategic point mutations that mimic phosphorylation. Our results reveal that first, phosphorylation at three target sites (S818, S831, and T840) is necessary for the change in the secondary structure of the existing disordered native sequence. Also, the results suggest that the formation of the tertiary structure through electrostatic interaction involving one specific phosphorylation site (S831) stabilizes the structure and renders conformational rigidity.
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Affiliation(s)
- Sudeshna Chatterjee
- Department
of Chemistry and Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, United States
| | - Chayan Dutta
- Department
of Chemistry and Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, United States
| | - Nicole C. Carrejo
- Department
of Chemistry and Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, United States
| | - Christy F. Landes
- Department
of Chemistry and Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, United States
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7
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Chatterjee S, Ade C, Nurik CE, Carrejo NC, Dutta C, Jayaraman V, Landes CF. Phosphorylation Induces Conformational Rigidity at the C-Terminal Domain of AMPA Receptors. J Phys Chem B 2019; 123:130-137. [PMID: 30537817 DOI: 10.1021/acs.jpcb.8b10749] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The intracellular C-terminal domain (CTD) of AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptor undergoes phosphorylation at specific locations during long-term potentiation. This modification enhances conductance through the AMPA receptor ion channel and thus potentially plays a crucial role in modulating receptor trafficking and signaling. However, because the CTD structure is largely unresolved, it is difficult to establish if phosphorylation induces conformational changes that might play a role in enhancing channel conductance. Herein, we utilize single-molecule Förster resonance energy transfer (smFRET) spectroscopy to probe the conformational changes of a section of the AMPA receptor CTD, under the conditions of point-mutated phosphomimicry. Multiple analysis algorithms fail to identify stable conformational states within the smFRET distributions, consistent with a lack of well-defined secondary structure. Instead, our results show that phosphomimicry induces conformational rigidity to the CTD, and such rigidity is electrostatically tunable.
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Affiliation(s)
- Sudeshna Chatterjee
- Department of Chemistry , Rice University , Houston , Texas 77005 , United States
| | - Carina Ade
- Department of Chemistry , Rice University , Houston , Texas 77005 , United States
| | - Caitlin E Nurik
- Department of Biochemistry and Molecular Biology , University of Texas Health Medical School , Houston , Texas 77005 , United States
| | - Nicole C Carrejo
- Department of Chemistry , Rice University , Houston , Texas 77005 , United States
| | - Chayan Dutta
- Department of Chemistry , Rice University , Houston , Texas 77005 , United States
| | - Vasanthi Jayaraman
- Department of Biochemistry and Molecular Biology , University of Texas Health Medical School , Houston , Texas 77005 , United States
| | - Christy F Landes
- Department of Chemistry , Rice University , Houston , Texas 77005 , United States.,Department of Electrical and Computer Engineering , Rice University , Houston , Texas 77005 , United States
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8
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Yadav R, Lu HP. Revealing dynamically-organized receptor ion channel clusters in live cells by a correlated electric recording and super-resolution single-molecule imaging approach. Phys Chem Chem Phys 2018. [PMID: 29517089 DOI: 10.1039/c7cp08030a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The N-methyl-d-aspartate (NMDA) receptor ion-channel is activated by the binding of ligands, along with the application of action potential, important for synaptic transmission and memory functions. Despite substantial knowledge of the structure and function, the gating mechanism of the NMDA receptor ion channel for electric on-off signals is still a topic of debate. We investigate the NMDA receptor partition distribution and the associated channel's open-close electric signal trajectories using a combined approach of correlating single-molecule fluorescence photo-bleaching, single-molecule super-resolution imaging, and single-channel electric patch-clamp recording. Identifying the compositions of NMDA receptors, their spatial organization and distributions over live cell membranes, we observe that NMDA receptors are organized inhomogeneously: nearly half of the receptor proteins are individually dispersed; whereas others exist in heterogeneous clusters of around 50 nm in size as well as co-localized within the diffraction limited imaging area. We demonstrate that inhomogeneous interactions and partitions of the NMDA receptors can be a cause of the heterogeneous gating mechanism of NMDA receptors in living cells. Furthermore, comparing the imaging results with the ion-channel electric current recording, we propose that the clustered NMDA receptors may be responsible for the variation in the current amplitude observed in the on-off two-state ion-channel electric signal trajectories. Our findings shed new light on the fundamental structure-function mechanism of NMDA receptors and present a conceptual advancement of the ion-channel mechanism in living cells.
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Affiliation(s)
- Rajeev Yadav
- Center for Photochemical Sciences, Department of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403, USA.
| | - H Peter Lu
- Center for Photochemical Sciences, Department of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403, USA.
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9
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Miller H, Zhou Z, Shepherd J, Wollman AJM, Leake MC. Single-molecule techniques in biophysics: a review of the progress in methods and applications. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2018; 81:024601. [PMID: 28869217 DOI: 10.1088/1361-6633/aa8a02] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Single-molecule biophysics has transformed our understanding of biology, but also of the physics of life. More exotic than simple soft matter, biomatter lives far from thermal equilibrium, covering multiple lengths from the nanoscale of single molecules to up to several orders of magnitude higher in cells, tissues and organisms. Biomolecules are often characterized by underlying instability: multiple metastable free energy states exist, separated by levels of just a few multiples of the thermal energy scale k B T, where k B is the Boltzmann constant and T absolute temperature, implying complex inter-conversion kinetics in the relatively hot, wet environment of active biological matter. A key benefit of single-molecule biophysics techniques is their ability to probe heterogeneity of free energy states across a molecular population, too challenging in general for conventional ensemble average approaches. Parallel developments in experimental and computational techniques have catalysed the birth of multiplexed, correlative techniques to tackle previously intractable biological questions. Experimentally, progress has been driven by improvements in sensitivity and speed of detectors, and the stability and efficiency of light sources, probes and microfluidics. We discuss the motivation and requirements for these recent experiments, including the underpinning mathematics. These methods are broadly divided into tools which detect molecules and those which manipulate them. For the former we discuss the progress of super-resolution microscopy, transformative for addressing many longstanding questions in the life sciences, and for the latter we include progress in 'force spectroscopy' techniques that mechanically perturb molecules. We also consider in silico progress of single-molecule computational physics, and how simulation and experimentation may be drawn together to give a more complete understanding. Increasingly, combinatorial techniques are now used, including correlative atomic force microscopy and fluorescence imaging, to probe questions closer to native physiological behaviour. We identify the trade-offs, limitations and applications of these techniques, and discuss exciting new directions.
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Affiliation(s)
- Helen Miller
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, OX1 3PU, United Kingdom
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10
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Edwards D, Sommerhage F, Berry B, Nummer H, Raquet M, Clymer B, Stancescu M, Hickman JJ. Comparison of NMDA and AMPA Channel Expression and Function between Embryonic and Adult Neurons Utilizing Microelectrode Array Systems. ACS Biomater Sci Eng 2017; 3:3525-3533. [PMID: 29250595 PMCID: PMC5728088 DOI: 10.1021/acsbiomaterials.7b00596] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 11/13/2017] [Indexed: 12/27/2022]
Abstract
![]()
Microelectrode
arrays (MEAs) are innovative tools used to perform
electrophysiological experiments for the study of electrical activity
and connectivity in populations of neurons from dissociated cultures.
Reliance upon neurons derived from embryonic tissue is a common limitation
of neuronal/MEA hybrid systems and perhaps of neuroscience research
in general, and the use of adult neurons could model fully functional
in vivo parameters more closely. Spontaneous network activity was
concurrently recorded from both embryonic and adult rat neurons cultured
on MEAs for up to 10 weeks in vitro to characterize the synaptic connections
between cell types. The cultures were exposed to synaptic transmission
antagonists against NMDA and AMPA channels, which revealed significantly
different receptor profiles of adult and embryonic networks in vitro.
In addition, both embryonic and adult neurons were evaluated for NMDA
and AMPA channel subunit expression over five weeks in vitro. The
results established that neurons derived from embryonic tissue did
not express mature synaptic channels for several weeks in vitro under
defined conditions. Consequently, the embryonic response to synaptic
antagonists was significantly different than that of neurons derived
from adult tissue sources. These results are especially significant
because most studies reported with embryonic hippocampal neurons do
not begin at two to four weeks in culture. In addition, the utilization
of MEAs in lieu of patch-clamp electrophysiology avoided a large-scale,
labor-intensive study. These results establish the utility of this
unique hybrid system derived from adult hippocampal tissue in combination
with MEAs and offer a more appropriate representation of in vivo function
for drug discovery. It has application for neuronal development and
regeneration as well as for investigations into neurodegenerative
disease, traumatic brain injury, and stroke.
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Affiliation(s)
- Darin Edwards
- NanoScience Technology Center, University of Central Florida, 12424 Research Parkway, Orlando, Florida 32826, United States.,The Burnett School of Biomedical Sciences, University of Central Florida, UCF College of Medicine, 6850 Lake Nona Blvd, Orlando, Florida 32827, United States
| | - Frank Sommerhage
- NanoScience Technology Center, University of Central Florida, 12424 Research Parkway, Orlando, Florida 32826, United States
| | - Bonnie Berry
- NanoScience Technology Center, University of Central Florida, 12424 Research Parkway, Orlando, Florida 32826, United States.,The Burnett School of Biomedical Sciences, University of Central Florida, UCF College of Medicine, 6850 Lake Nona Blvd, Orlando, Florida 32827, United States
| | - Hanna Nummer
- NanoScience Technology Center, University of Central Florida, 12424 Research Parkway, Orlando, Florida 32826, United States
| | - Martina Raquet
- NanoScience Technology Center, University of Central Florida, 12424 Research Parkway, Orlando, Florida 32826, United States
| | - Brad Clymer
- NanoScience Technology Center, University of Central Florida, 12424 Research Parkway, Orlando, Florida 32826, United States
| | - Maria Stancescu
- NanoScience Technology Center, University of Central Florida, 12424 Research Parkway, Orlando, Florida 32826, United States
| | - James J Hickman
- NanoScience Technology Center, University of Central Florida, 12424 Research Parkway, Orlando, Florida 32826, United States.,The Burnett School of Biomedical Sciences, University of Central Florida, UCF College of Medicine, 6850 Lake Nona Blvd, Orlando, Florida 32827, United States
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11
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Osakada Y, Zhang K. Single-Particle Tracking Reveals a Dynamic Role of Actin Filaments in Assisting Long-Range Axonal Transport in Neurons. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2017. [DOI: 10.1246/bcsj.20170090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Yasuko Osakada
- Department of Chemistry, Stanford University, Stanford, CA 94305 (USA)
- The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047
| | - Kai Zhang
- Department of Biochemistry, School of Molecular and Cellular Biology, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, 314 B Roger Adams Laboratory, Urbana, Illinois, 61801 (USA)
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12
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Siriwardana K, Vithanage BCN, Zou S, Zhang D. Quantification of the Depolarization and Anisotropy of Fluorophore Stokes-Shifted Fluorescence, On-Resonance Fluorescence, and Rayleigh Scattering. Anal Chem 2017; 89:6686-6694. [PMID: 28503920 DOI: 10.1021/acs.analchem.7b00907] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Fluorophores are important but optically complicated photonic materials as they are simultaneous photon absorbers, emitters, and scatterers. Existing studies on fluorophore optical properties have been focused almost exclusively on its photon absorption and Stokes-shifted fluorescence (SSF) with scant information on the fluorophore photon scattering and on-resonance fluorescence (ORF). Presented herein is a unified theoretical framework and experimental approach for quantification of the fluorophore SSF, ORF, and scattering depolarization and anisotropy using a combination of fluorophore UV-vis, fluorescence emission, and resonance synchronous spectroscopic spectral measurements. A mathematical model for calculating fluorophore ORF and scattering cross sections has been developed that uses polystyrene nanoparticles as the external reference. The fluorophore scattering cross section is ∼10-fold smaller than its ORF counterparts for all the six model fluorophores, but more than 6 orders of magnitude larger than the water scattering cross section. Another finding is that the fluorophore ORF has a depolarization close to 1, while its Rayleigh scattering has zero depolarization. This enables the experimental separation of the fluorophore ORF and photon scattering features in the fluorophore resonance synchronous spectra. In addition to opening a new avenue for material characterization, the methods and insights derived from this study should be important for developing new analytical methods that exploit the fluorophore ORF and photon scattering properties.
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Affiliation(s)
- Kumudu Siriwardana
- Department of Chemistry, Mississippi State University , Mississippi State, Mississippi 39762, United States
| | - Buddhini C N Vithanage
- Department of Chemistry, Mississippi State University , Mississippi State, Mississippi 39762, United States
| | - Shengli Zou
- Department of Chemistry, University of Central Florida , Orlando, Florida 32816, United States
| | - Dongmao Zhang
- Department of Chemistry, Mississippi State University , Mississippi State, Mississippi 39762, United States
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13
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Zhang Z, Yomo D, Gradinaru C. Choosing the right fluorophore for single-molecule fluorescence studies in a lipid environment. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:1242-1253. [PMID: 28392350 DOI: 10.1016/j.bbamem.2017.04.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 03/14/2017] [Accepted: 04/05/2017] [Indexed: 10/19/2022]
Abstract
Nonspecific interactions between lipids and fluorophores can alter the outcomes of single-molecule spectroscopy of membrane proteins in live cells, liposomes or lipid nanodiscs and of cytosolic proteins encapsulated in liposomes or tethered to supported lipid bilayers. To gain insight into these effects, we examined interactions between 9 dyes that are commonly used as labels for single-molecule fluorescence (SMF) and 6 standard lipids including cationic, zwitterionic and anionic types. The diffusion coefficients of dyes in the absence and presence of set amounts of lipid vesicles were measured by fluorescence correlation spectroscopy (FCS). The partition coefficients and the free energies of partitioning for different fluorophore-lipid pairs were obtained by global fitting of the titration FCS curves. Lipids with different charges, head groups and degrees of chain saturation were investigated, and interactions with dyes are discussed in terms of hydrophobic, electrostatic and steric contributions. Fluorescence imaging of individual fluorophores adsorbed on supported lipid bilayers provides visualization and additional quantification of the strength of dye-lipid interaction in the context of single-molecule measurements. By dissecting fluorophore-lipid interactions, our study provides new insights into setting up single-molecule fluorescence spectroscopy experiments with minimal interference from interactions between fluorescent labels and lipids in the environment.
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Affiliation(s)
- Zhenfu Zhang
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada; Department of Physics, University of Toronto, Toronto, Ontario M5S 1A7, Canada
| | - Dan Yomo
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada; Department of Physics, University of Toronto, Toronto, Ontario M5S 1A7, Canada
| | - Claudiu Gradinaru
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada; Department of Physics, University of Toronto, Toronto, Ontario M5S 1A7, Canada.
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14
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Chen W, Chen CL, Zhang Z, Chen YA, Chao WC, Su J, Tian H, Chou PT. Snapshotting the Excited-State Planarization of Chemically Locked N,N′-Disubstituted Dihydrodibenzo[a,c]phenazines. J Am Chem Soc 2017; 139:1636-1644. [DOI: 10.1021/jacs.6b11789] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Wei Chen
- Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science & Technology, Shanghai 200237, P. R. China
| | - Chi-Lin Chen
- Department
of Chemistry, National Taiwan University, Taipei, 10617 Taiwan, R.O.C
| | - Zhiyun Zhang
- Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science & Technology, Shanghai 200237, P. R. China
- Department
of Chemistry, National Taiwan University, Taipei, 10617 Taiwan, R.O.C
| | - Yi-An Chen
- Department
of Chemistry, National Taiwan University, Taipei, 10617 Taiwan, R.O.C
| | - Wei-Chih Chao
- Department
of Chemistry, National Taiwan University, Taipei, 10617 Taiwan, R.O.C
| | - Jianhua Su
- Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science & Technology, Shanghai 200237, P. R. China
| | - He Tian
- Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science & Technology, Shanghai 200237, P. R. China
| | - Pi-Tai Chou
- Department
of Chemistry, National Taiwan University, Taipei, 10617 Taiwan, R.O.C
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15
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Sasmal DK, Pulido LE, Kasal S, Huang J. Single-molecule fluorescence resonance energy transfer in molecular biology. NANOSCALE 2016; 8:19928-19944. [PMID: 27883140 PMCID: PMC5145784 DOI: 10.1039/c6nr06794h] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Single-molecule fluorescence resonance energy transfer (smFRET) is a powerful technique for studying the conformation dynamics and interactions of individual biomolecules. In this review, we describe the concept and principle of smFRET, illustrate general instrumentation and microscopy settings for experiments, and discuss the methods and algorithms for data analysis. Subsequently, we review applications of smFRET in protein conformational changes, ion channel open-close properties, receptor-ligand interactions, nucleic acid structure regulation, vesicle fusion, and force induced conformational dynamics. Finally, we discuss the main limitations of smFRET in molecular biology.
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Affiliation(s)
- Dibyendu K Sasmal
- The Institute for Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA.
| | - Laura E Pulido
- The Institute for Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA.
| | - Shan Kasal
- The Institute for Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA.
| | - Jun Huang
- The Institute for Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA.
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