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Pandit S, Bhattacharjee S, Seth D. Photoluminescence Properties of Graphene Oxide in Non-Aqueous Solvents. Chemphyschem 2023:e202300373. [PMID: 37846212 DOI: 10.1002/cphc.202300373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2023] [Revised: 10/15/2023] [Accepted: 10/16/2023] [Indexed: 10/18/2023]
Abstract
Detailed attention to the interaction between graphene oxide (GO) and various organic fluorophores has been documented in literature as a result of which the impact of GO on the photophysical properties of the fluorophores is well known to the scientific community. However, the photoluminescence (PL) properties of GO in polar aprotic solvents are yet to be established. In this article, the PL properties of GO in polar aprotic solvents using various spectroscopic techniques have been reported. n-π* transition due to the C=O bonds in the sp3 hybrid regions and π-π* transition due to C=C bonds in the sp2 hybrid are prominent in GO. The presence of quasi-molecules within sp2 -sp3 domains acts as PL centers located in the sp3 matrixes of GO are responsible for the PL properties. This study showcases the presence of multiple emissive states of GO in polar aprotic solvents and conveys the fact that the PL properties of GO are very much wavelength-dependent.
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Affiliation(s)
- Souvik Pandit
- Department of Chemistry, Indian Institute of Technology Patna, 801103, Patna, Bihar, India
| | - Sanyukta Bhattacharjee
- Department of Chemistry, Indian Institute of Technology Patna, 801103, Patna, Bihar, India
| | - Debabrata Seth
- Department of Chemistry, Indian Institute of Technology Patna, 801103, Patna, Bihar, India
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2
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van Zanten TS, S GP, Mayor S. Quantitative fluorescence emission anisotropy microscopy for implementing homo-fluorescence resonance energy transfer measurements in living cells. Mol Biol Cell 2023; 34:tp1. [PMID: 37144969 DOI: 10.1091/mbc.e22-09-0446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023] Open
Abstract
Quantitative fluorescence emission anisotropy microscopy reveals the organization of fluorescently labeled cellular components and allows their characterization in terms of changes in either rotational diffusion or homo-Förster's energy transfer characteristics in living cells. These properties provide insights into molecular organization, such as orientation, confinement, and oligomerization in situ. Here we elucidate how quantitative measurements of anisotropy using multiple microscope systems may be made by bringing out the main parameters that influence the quantification of fluorescence emission anisotropy. We focus on a variety of parameters that contribute to errors associated with the measurement of emission anisotropy in a microscope. These include the requirement for adequate photon counts for the necessary discrimination of anisotropy values, the influence of extinction ratios of the illumination source, the detector system, the role of numerical aperture, and excitation wavelength. All these parameters also affect the ability to capture the dynamic range of emission anisotropy necessary for quantifying its reduction due to homo-FRET and other processes. Finally, we provide easily implementable tests to assess whether homo-FRET is a cause for the observed emission depolarization.
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Affiliation(s)
- Thomas S van Zanten
- Cell Biology Group, National Centre for Biological Sciences, UAS-GKVK Campus, Tata Institute for Fundamental Research, Bangalore 560065, India
| | - Greeshma Pradeep S
- Cell Biology Group, National Centre for Biological Sciences, UAS-GKVK Campus, Tata Institute for Fundamental Research, Bangalore 560065, India
| | - Satyajit Mayor
- Cell Biology Group, National Centre for Biological Sciences, UAS-GKVK Campus, Tata Institute for Fundamental Research, Bangalore 560065, India
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3
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Chattopadhyay A, Biswas SC, Rukmini R, Saha S, Samanta A. Lack of Environmental Sensitivity of a Naturally Occurring Fluorescent Analog of Cholesterol. J Fluoresc 2021; 31:1401-1407. [PMID: 34224042 DOI: 10.1007/s10895-021-02767-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 06/01/2021] [Indexed: 11/26/2022]
Abstract
Dehydroergosterol (DHE, Δ5,7,9(11),22-ergostatetraen-3β-ol) is a naturally occurring fluorescent analog of cholesterol found in yeast. Since DHE has been shown to faithfully mimic cholesterol in a large number of biophysical, biochemical, and cell biological studies, it is widely used to explore cholesterol organization, dynamics and trafficking in model and biological membranes. In this work, we show that DHE, in spite of its localization at the membrane interface, does not exhibit red edge excitation shift (REES) in model membranes, irrespective of the membrane phase. These results are reinforced by semi-empirical quantum chemical calculations of dipole moment changes of DHE in ground and excited states, which show a very small change in the dipole moment of DHE upon excitation. We conclude that DHE fluorescence exhibits lack of environmental sensitivity, despite its usefulness in monitoring cholesterol organization, dynamics and traffic in model and biological membranes.
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Affiliation(s)
| | - Samares C Biswas
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500 007, India
| | - Raju Rukmini
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500 007, India
| | - Satyen Saha
- School of Chemistry, University of Hyderabad, Hyderabad, 500 046, India
- Department of Chemistry, Banaras Hindu University, Varanasi, 221 005, India
| | - Anunay Samanta
- School of Chemistry, University of Hyderabad, Hyderabad, 500 046, India
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4
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Silicon-doped carbon quantum dots with blue and green emission are a viable ratiometric fluorescent probe for hydroquinone. Mikrochim Acta 2019; 186:399. [DOI: 10.1007/s00604-019-3490-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 05/05/2019] [Indexed: 01/14/2023]
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5
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Halder S, Samanta S, Das G. Exploring the potential of a urea derivative: an AIE-luminogen and its interaction with human serum albumin in aqueous medium. Analyst 2019; 144:2696-2703. [DOI: 10.1039/c9an00102f] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A simple AIE active urea molecule (L1) can selectively interact with HSAviaturn-on fluorescence response in aqueous medium.
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Affiliation(s)
- Senjuti Halder
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati 781039
- India
| | - Soham Samanta
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati 781039
- India
| | - Gopal Das
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati 781039
- India
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6
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7
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Endocytosis of a functionally enhanced GFP-tagged transferrin receptor in CHO cells. PLoS One 2015; 10:e0122452. [PMID: 25803700 PMCID: PMC4372551 DOI: 10.1371/journal.pone.0122452] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 02/11/2015] [Indexed: 11/19/2022] Open
Abstract
The endocytosis of transferrin receptor (TfR) has served as a model to study the receptor-targeted cargo delivery system for cancer therapy for many years. To accurately evaluate and optically measure this TfR targeting delivery in vitro, a CHO cell line with enhanced green fluorescent protein (EGFP)-tagged human TfR was established. A chimera of the hTfR and EGFP was engineered by fusing EGFP to the amino terminus of hTfR. Data were provided to demonstrate that hTfR-EGFP chimera was predominantly localized on the plasma membrane with some intracellular fluorescent structures on CHO cells and the EGFP moiety did not affect the endocytosis property of hTfR. Receptor internalization occurred similarly to that of HepG2 cells expressing wild-type hTfR. The internalization percentage of this chimeric receptor was about 81±3% of wild type. Time-dependent co-localization of hTfR-EGFP and PE-conjugated anti-hTfR mAb in living cells demonstrated the trafficking of mAb-receptor complexes through the endosomes followed by segregation of part of the mAb and receptor at the late stages of endocytosis. The CHO-hTfR cells preferentially took up anti-hTfR mAb conjugated nanoparticles. This CHO-hTfR cell line makes it feasible for accurate evaluation and visualization of intracellular trafficking of therapeutic agents conjugated with transferrin or Abs targeting the hTfRs.
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Shah E, Mahapatra P, Bedekar AV, Soni HP. Immobilization of Thermomyces lanuginosus lipase on ZnO nanoparticles: mimicking the interfacial environment. RSC Adv 2015. [DOI: 10.1039/c5ra02249e] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In this study, we propose that enzyme activity on immobilization can be controlled and enhanced by providing the environment mimicking the lipid/water interface.
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Affiliation(s)
- Ekta Shah
- Department of Chemistry
- Faculty of Science
- The Maharaja Sayajirao University of Baroda
- Vadodara-390 002
- India
| | - Paramita Mahapatra
- Department of Chemistry
- Faculty of Science
- The Maharaja Sayajirao University of Baroda
- Vadodara-390 002
- India
| | - Ashutosh V. Bedekar
- Department of Chemistry
- Faculty of Science
- The Maharaja Sayajirao University of Baroda
- Vadodara-390 002
- India
| | - Hemant P. Soni
- Department of Chemistry
- Faculty of Science
- The Maharaja Sayajirao University of Baroda
- Vadodara-390 002
- India
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9
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Cushing SK, Li M, Huang F, Wu N. Origin of strong excitation wavelength dependent fluorescence of graphene oxide. ACS NANO 2014; 8:1002-1013. [PMID: 24359152 DOI: 10.1021/nn405843d] [Citation(s) in RCA: 198] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The peak fluorescence emission of conventional fluorophores such as organic dyes and inorganic quantum dots is independent of the excitation wavelength. In contrast, the position of the peak fluorescence of graphene oxide (GO) in a polar solvent is heavily dependent on the excitation wavelength. The present work has discovered that the strong excitation wavelength dependent fluorescence in GO is originated from the "giant red-edge effect", which breaks Kasha's rule. When GO sheets are present in a polar solvent, the solvation dynamics slow down to the same time scale as the fluorescence due to the local environment of the GO sheet. Consequently, the fluorescence peak of GO broadens and red-shifts up to 200 nm with an increase in the excitation wavelength. The giant red-edge effect of GO disappears in a nonpolar solvent, leading to a narrow fluorescence peak that is independent of the excitation wavelength. Discovery of the underlying strong excitation wavelength dependent fluorescence mechanism provides guidelines for the design of graphene oxide-based optical devices.
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Affiliation(s)
- Scott K Cushing
- Department of Mechanical and Aerospace Engineering, West Virginia University , Morgantown, West Virginia 26506-6106, United States
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10
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Chattopadhyay A, Haldar S. Dynamic insight into protein structure utilizing red edge excitation shift. Acc Chem Res 2014; 47:12-9. [PMID: 23981188 DOI: 10.1021/ar400006z] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Proteins are considered the workhorses in the cellular machinery. They are often organized in a highly ordered conformation in the crowded cellular environment. These conformations display characteristic dynamics over a range of time scales. An emerging consensus is that protein function is critically dependent on its dynamics. The subtle interplay between structure and dynamics is a hallmark of protein organization and is essential for its function. Depending on the environmental context, proteins can adopt a range of conformations such as native, molten globule, unfolded (denatured), and misfolded states. Although protein crystallography is a well established technique, it is not always possible to characterize various protein conformations by X-ray crystallography due to transient nature of these states. Even in cases where structural characterization is possible, the information obtained lacks dynamic component, which is needed to understand protein function. In this overall scenario, approaches that reveal information on protein dynamics are much appreciated. Dynamics of confined water has interesting implications in protein folding. Interfacial hydration combines the motion of water molecules with the slow moving protein molecules. The red edge excitation shift (REES) approach becomes relevant in this context. REES is defined as the shift in the wavelength of maximum fluorescence emission toward higher wavelengths, caused by a shift in the excitation wavelength toward the red edge of absorption spectrum. REES arises due to slow rates (relative to fluorescence lifetime) of solvent relaxation (reorientation) around an excited state fluorophore in organized assemblies such as proteins. Consequently, REES depends on the environment-induced motional restriction imposed on the solvent molecules in the immediate vicinity of the fluorophore. In the case of a protein, the confined water in the protein creates a dipolar field that acts as the solvent for a fluorophore in the protein. In this Account, we focus on REES to monitor organization and dynamics of soluble and membrane proteins utilizing intrinsic protein fluorescence. We discuss here the application of REES in various conformations of proteins. While application of REES to proteins in native conformation has been in use for a long time, our work highlights the potential of this approach in case of molten globule and denatured conformations. For example, we have demonstrated the presence of residual structure, that could not be detected using other methods, by REES of denatured spectrin. Given the functional relevance of such residual structures, these results are very far reaching. We discuss here the application of REES to molten globule conformation and to the green fluorescent protein (GFP). The case of GFP is particularly interesting since the dipolar field in this case is provided by the protein matrix itself and not confined water. We envision that future applications of REES in proteins will involve generating a dynamic hydration map of the protein, which would allow us to explore protein function in terms of local dynamics and hydration.
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Affiliation(s)
- Amitabha Chattopadhyay
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007 India
| | - Sourav Haldar
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007 India
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11
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Chaudhuri A, Basu P, Haldar S, Kombrabail M, Krishnamoorthy G, Rajarathnam K, Chattopadhyay A. Organization and dynamics of the N-terminal domain of chemokine receptor CXCR1 in reverse micelles: effect of graded hydration. J Phys Chem B 2013; 117:1225-33. [PMID: 23311880 DOI: 10.1021/jp3095352] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Water plays a fundamental role in the folding, structure, dynamics, and function of proteins and peptides. The extracellular N-terminal domain of chemokine receptors is crucial in mediating binding affinity, receptor selectivity, and regulating function. The flexible N-terminal domain becomes ordered in membranes and membrane-mimetic assemblies, thereby indicating that the membrane could play an important role in regulating CXC chemokine receptor 1 (CXCR1) function. In view of the role of hydration in lipid-protein interactions in membranes, we explored the organization and dynamics of a 34-mer peptide of the CXCR1 N-terminal domain in reverse micelles by utilizing a combination of fluorescence-based approaches and circular dichroism spectroscopy. Our results show that the secondary structure adopted by the CXCR1 N-domain is critically dependent on hydration. The tryptophan residues of the CXCR1 N-domain experience motional restriction and exhibit red edge excitation shift (REES) upon incorporation in reverse micelles. REES and fluorescence lifetime exhibit reduction with increasing reverse micellar hydration. Time-resolved fluorescence anisotropy measurements reveal the effect of hydration on peptide rotational dynamics. Taken together, these results constitute the first report demonstrating modulation in the organization and dynamics of the N-terminal domain of a chemokine receptor in a membrane-like environment of varying hydration. We envisage that these results are relevant in the context of hydration in the function of G protein-coupled receptors.
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Affiliation(s)
- Arunima Chaudhuri
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India
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12
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Chatterjee A, Maity B, Seth D. The photophysics of 7-(N,N′-diethylamino)coumarin-3-carboxylic acid in water/AOT/isooctane reverse micelles: an excitation wavelength dependent study. Phys Chem Chem Phys 2013; 15:1894-906. [DOI: 10.1039/c2cp43483k] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Jana S, Dalapati S, Ghosh S, Guchhait N. Study of microheterogeneous environment of protein Human Serum Albumin by an extrinsic fluorescent reporter: A spectroscopic study in combination with Molecular Docking and Molecular Dynamics Simulation. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2012; 112:48-58. [DOI: 10.1016/j.jphotobiol.2012.04.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Revised: 03/30/2012] [Accepted: 04/06/2012] [Indexed: 10/28/2022]
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14
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Chaudhuri A, Haldar S, Chattopadhyay A. Structural transition in micelles: novel insight into microenvironmental changes in polarity and dynamics. Chem Phys Lipids 2012; 165:497-504. [DOI: 10.1016/j.chemphyslip.2011.09.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Revised: 09/15/2011] [Accepted: 09/16/2011] [Indexed: 01/23/2023]
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15
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Jana S, Dalapati S, Ghosh S, Guchhait N. Binding interaction between plasma protein bovine serum albumin and flexible charge transfer fluorophore: A spectroscopic study in combination with molecular docking and molecular dynamics simulation. J Photochem Photobiol A Chem 2012. [DOI: 10.1016/j.jphotochem.2011.12.002] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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16
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Application of NBD-Labeled Lipids in Membrane and Cell Biology. SPRINGER SERIES ON FLUORESCENCE 2012. [DOI: 10.1007/4243_2012_43] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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17
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Jana S, Ghosh S, Dalapati S, Guchhait N. Exploring structural change of protein bovine serum albumin by external perturbation using extrinsic fluorescence probe: spectroscopic measurement, molecular docking and molecular dynamics simulation. Photochem Photobiol Sci 2012; 11:323-32. [DOI: 10.1039/c1pp05180f] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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18
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19
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Singh P, Baheti A, Thomas KRJ. Synthesis and Optical Properties of Acidochromic Amine-Substituted Benzo[a]phenazines. J Org Chem 2011; 76:6134-45. [DOI: 10.1021/jo200857p] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Prachi Singh
- Organic Materials Lab, Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee-247 667, India
| | - Abhishek Baheti
- Organic Materials Lab, Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee-247 667, India
| | - K. R. Justin Thomas
- Organic Materials Lab, Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee-247 667, India
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20
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Ganguly S, Clayton AHA, Chattopadhyay A. Organization of higher-order oligomers of the serotonin₁(A) receptor explored utilizing homo-FRET in live cells. Biophys J 2011; 100:361-8. [PMID: 21244832 DOI: 10.1016/j.bpj.2010.12.3692] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Revised: 11/16/2010] [Accepted: 12/08/2010] [Indexed: 10/18/2022] Open
Abstract
The serotonin₁(A) receptor is a representative member of the GPCR superfamily and serves as an important drug target. The possible role of GPCR oligomerization in receptor function is an active area of research. We monitored the oligomerization state of serotonin₁(A) receptors using homo-FRET and fluorescence lifetime measurements. Homo-FRET is estimated by a reduction in fluorescence anisotropy and provides a superior approach for exploring oligomerization. In addition, homo-FRET offers the possibility of detecting higher-order oligomers. On the basis of an observed increase in fluorescence anisotropy upon progressive photobleaching and analysis of the difference between the extrapolated anisotropy and the predicted anisotropy of an immobile monomer, we propose the presence of constitutive oligomers of the serotonin₁(A) receptor. To the best of our knowledge, these results constitute the first report of higher-order oligomers for the serotonin₁(A) receptor. We further show that cholesterol depletion and antagonist treatment result in a reduced population of higher-order oligomers. In contrast, agonist stimulation and destabilization of the actin cytoskeleton lead to an increased contribution from higher oligomers. These results provide novel insight into the oligomerization status of the serotonin₁(A) receptor that could enhance the ability to design better therapeutic strategies to combat diseases related to malfunctioning of GPCRs.
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Affiliation(s)
- Sourav Ganguly
- Centre for Cellular and Molecular Biology, Hyderabad, India
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21
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Haldar S, Chaudhuri A, Chattopadhyay A. Organization and dynamics of membrane probes and proteins utilizing the red edge excitation shift. J Phys Chem B 2011; 115:5693-706. [PMID: 21428321 DOI: 10.1021/jp200255e] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Dynamics of confined water has interesting implications in the organization and function of molecular assemblies such as membranes. A direct consequence of this type of organization is the restriction imposed on the mobility of the constituent structural units. Interestingly, this restriction (confinement) of mobility couples the motion of solvent (water) molecules with the slow moving molecules in the assembly. It is in this context that the red edge excitation shift (REES) represents a sensitive approach to monitor the environment and dynamics around a fluorophore in such organized assemblies. A shift in the wavelength of maximum fluorescence emission toward higher wavelengths, caused by a shift in the excitation wavelength toward the red edge of the absorption band, is termed REES. REES relies on slow solvent reorientation in the excited state of a fluorophore that can be used to monitor the environment and dynamics around a fluorophore in a host assembly. In this article, we focus on the application of REES to monitor organization and dynamics of membrane probes and proteins.
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Affiliation(s)
- Sourav Haldar
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007 India
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22
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Transbilayer organization of membrane cholesterol at low concentrations: Implications in health and disease. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1808:19-25. [PMID: 21035427 DOI: 10.1016/j.bbamem.2010.10.013] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Revised: 10/20/2010] [Accepted: 10/22/2010] [Indexed: 02/06/2023]
Abstract
Cholesterol is an essential and representative lipid in higher eukaryotic cellular membranes and is often found distributed nonrandomly in domains in biological membranes. A large body of literature exists on the organization of cholesterol in plasma membranes or membranes with high cholesterol content. However, very little is known about organization of cholesterol in membranes containing low amounts of cholesterol such as the endoplasmic reticulum or inner mitochondrial membranes. In this review, we have traced the discovery and subsequent development of the concept of transbilayer cholesterol dimers (domains) in membranes at low concentrations. We have further discussed the role of membrane curvature and thickness on the transbilayer organization of cholesterol. Interestingly, this type of cholesterol organization could be relevant in cellular sorting and trafficking, and in pathological conditions.
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Kelkar DA, Chaudhuri A, Haldar S, Chattopadhyay A. Exploring tryptophan dynamics in acid-induced molten globule state of bovine α-lactalbumin: a wavelength-selective fluorescence approach. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2010; 39:1453-63. [PMID: 20372885 DOI: 10.1007/s00249-010-0603-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2010] [Revised: 03/01/2010] [Accepted: 03/23/2010] [Indexed: 10/19/2022]
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25
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Organization and dynamics of tryptophans in the molten globule state of bovine α-lactalbumin utilizing wavelength-selective fluorescence approach: Comparisons with native and denatured states. Biochem Biophys Res Commun 2010; 394:1082-6. [DOI: 10.1016/j.bbrc.2010.03.130] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Accepted: 03/20/2010] [Indexed: 10/19/2022]
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26
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Ghosh S, Guchhait N. Fluorescent Probing of Urea-induced Chemical Unfolding of Bovine Serum Albumin by Intramolecular Charge Transfer Fluorescence Probe E-3-(4-Dimethylamino-Naphthalen-1-yl)-Acrylic Acid. Photochem Photobiol 2010; 86:290-6. [DOI: 10.1111/j.1751-1097.2009.00665.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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27
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Green fluorescent protein: a molecular lantern that illuminates the cellular interior. J Biosci 2009; 34:169-72. [PMID: 19550031 DOI: 10.1007/s12038-009-0019-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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28
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Ghosh S, Guchhait N. Chemically Induced Unfolding of Bovine Serum Albumin by Urea and Sodium Dodecyl Sulfate: A Spectral Study with the Polarity-Sensitive Charge-Transfer Fluorescent Probe (E)-3-(4-Methylaminophenyl)acrylic Acid Methyl Ester. Chemphyschem 2009; 10:1664-71. [DOI: 10.1002/cphc.200900161] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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29
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Shrivastava S, Haldar S, Gimpl G, Chattopadhyay A. Orientation and Dynamics of a Novel Fluorescent Cholesterol Analogue in Membranes of Varying Phase. J Phys Chem B 2009; 113:4475-81. [DOI: 10.1021/jp808309u] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sandeep Shrivastava
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India, and Institute of Biochemistry, Johannes Gutenberg-University of Mainz, Becherweg 30, D-55099 Mainz, Germany
| | - Sourav Haldar
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India, and Institute of Biochemistry, Johannes Gutenberg-University of Mainz, Becherweg 30, D-55099 Mainz, Germany
| | - Gerald Gimpl
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India, and Institute of Biochemistry, Johannes Gutenberg-University of Mainz, Becherweg 30, D-55099 Mainz, Germany
| | - Amitabha Chattopadhyay
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India, and Institute of Biochemistry, Johannes Gutenberg-University of Mainz, Becherweg 30, D-55099 Mainz, Germany
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Haldar S, Raghuraman H, Chattopadhyay A. Monitoring orientation and dynamics of membrane-bound melittin utilizing dansyl fluorescence. J Phys Chem B 2008; 112:14075-82. [PMID: 18842019 DOI: 10.1021/jp805299g] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Melittin is a cationic hemolytic peptide isolated from the European honey bee, Apis mellifera. In spite of a number of studies, there is no consensus regarding the orientation of melittin in membranes. In this study, we used a melittin analogue that is covalently labeled at its amino terminal (Gly-1) with the environment-sensitive 1-dimethylamino-5-sulfonylnaphthalene (dansyl) group to obtain information regarding the orientation and dynamics of the amino terminal region of membrane-bound melittin. Our results show that the dansyl group in Dns-melittin exhibits red edge excitation shift in vesicles of 1,2-dioleoyl-sn-glycero-3-phosphocholine, implying its localization in a motionally restricted region of the membrane. This is further supported by wavelength-dependent anisotropy and lifetime changes and time-resolved emission spectra characterized by dynamic Stokes shift, which indicates relatively slow solvent relaxation in the excited state. Membrane penetration depth analysis using the parallax method shows that the dansyl group is localized at a depth of approximately 18 A from the center of the bilayer in membrane-bound Dns-melittin. Further analysis of dansyl and tryptophan depths in Dns-melittin shows that the tilt angle between the helix axis of membrane-bound melittin and the bilayer normal is approximately 70 degrees. Our results therefore suggest that melittin adopts a pseudoparallel orientation in DOPC membranes at low concentration.
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Affiliation(s)
- Sourav Haldar
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Hyderabad, India
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