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Castillo-Velasquez C, Matamala E, Becerra D, Orio P, Brauchi SE. Optical recordings of organellar membrane potentials and the components of membrane conductance in lysosomes. J Physiol 2024; 602:1637-1654. [PMID: 38625711 DOI: 10.1113/jp283825] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 03/20/2024] [Indexed: 04/17/2024] Open
Abstract
The eukaryotic cell is highly compartmentalized with organelles. Owing to their function in transporting metabolites, metabolic intermediates and byproducts of metabolic activity, organelles are important players in the orchestration of cellular function. Recent advances in optical methods for interrogating the different aspects of organellar activity promise to revolutionize our ability to dissect cellular processes with unprecedented detail. The transport activity of organelles is usually coupled to the transport of charged species; therefore, it is not only associated with the metabolic landscape but also entangled with membrane potentials. In this context, the targeted expression of fluorescent probes for interrogating organellar membrane potential (Ψorg) emerges as a powerful approach, offering less-invasive conditions and technical simplicity to interrogate cellular signalling and metabolism. Different research groups have made remarkable progress in adapting a variety of optical methods for measuring and monitoring Ψorg. These approaches include using potentiometric dyes, genetically encoded voltage indicators, hybrid fluorescence resonance energy transfer sensors and photoinduced electron transfer systems. These studies have provided consistent values for the resting potential of single-membrane organelles, such as lysosomes, the Golgi and the endoplasmic reticulum. We can foresee the use of dynamic measurements of Ψorg to study fundamental problems in organellar physiology that are linked to serious cellular disorders. Here, we present an overview of the available techniques, a survey of the resting membrane potential of internal membranes and, finally, an open-source mathematical model useful to interpret and interrogate membrane-bound structures of small volume by using the lysosome as an example.
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Affiliation(s)
- Cristian Castillo-Velasquez
- Department of Physiology, Faculty of Medicine, Universidad Austral de Chile, Valdivia, Chile
- Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Valdivia, Chile
| | - Ella Matamala
- Department of Physiology, Faculty of Medicine, Universidad Austral de Chile, Valdivia, Chile
- Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Valdivia, Chile
| | - Diego Becerra
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Patricio Orio
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
- Instituto de Neurociencias, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Sebastian E Brauchi
- Department of Physiology, Faculty of Medicine, Universidad Austral de Chile, Valdivia, Chile
- Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Valdivia, Chile
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Krishnamoorthy G. Fluorescence spectroscopy for revealing mechanisms in biology: Strengths and pitfalls. J Biosci 2018; 43:555-567. [PMID: 30002272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
This article describes the basic principles of steady-state and time-resolved fluorescence. The formal equivalence of the two methodologies is described first, followed by the extra advantages of time-resolved methods in revealing population heterogeneity in complex systems encountered in biology. Several examples from the author's work are described in support of the above contention. Finally, several misinterpretations and pitfalls in the interpretation of fluorescence data and their remedy are described.
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Affiliation(s)
- G Krishnamoorthy
- Department of Biotechnology, Anna University, Chennai 600 025, India,
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Biener G, Masson-Meyers DS, Bumah VV, Hussey G, Stoneman MR, Enwemeka CS, Raicu V. Blue/violet laser inactivates methicillin-resistant Staphylococcus aureus by altering its transmembrane potential. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2017; 170:118-124. [DOI: 10.1016/j.jphotobiol.2017.04.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 03/21/2017] [Accepted: 04/05/2017] [Indexed: 12/20/2022]
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Bacalum M, Wang L, Boodts S, Yuan P, Leen V, Smisdom N, Fron E, Knippenberg S, Fabre G, Trouillas P, Beljonne D, Dehaen W, Boens N, Ameloot M. A Blue-Light-Emitting BODIPY Probe for Lipid Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:3495-3505. [PMID: 27003513 DOI: 10.1021/acs.langmuir.6b00478] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Here we describe a new BODIPY-based membrane probe (1) that provides an alternative to dialkylcarbocyanine dyes, such as DiI-C18, that can be excited in the blue spectral region. Compound 1 has unbranched octadecyl chains at the 3,5-positions and a meso-amino function. In organic solvents, the absorption and emission maxima of 1 are determined mainly by solvent acidity and dipolarity. The fluorescence quantum yield is high and reaches 0.93 in 2-propanol. The fluorescence decays are well fitted with a single-exponential in pure solvents and in small and giant unilamellar vesicles (GUV) with a lifetime of ca. 4 ns. Probe 1 partitions in the same lipid phase as DiI-C18(5) for lipid mixtures containing sphingomyelin and for binary mixtures of dipalmitoylphosphatidylcholine (DPPC) and dioleoylphosphatidylcholine (DOPC). The lipid phase has no effect on the fluorescence lifetime but influences the fluorescence anisotropy. The translational diffusion coefficients of 1 in GUVs and OLN-93 cells are of the same order as those reported for DiI-C18. The directions of the absorption and emission transition dipole moments of 1 are calculated to be parallel. This is reflected in the high steady-state fluorescence anisotropy of 1 in high ordered lipid phases. Molecular dynamic simulations of 1 in a model of the DOPC bilayer indicate that the average angle of the transition moments with respect to membrane normal is ca. 70°, which is comparable with the value reported for DiI-C18.
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Affiliation(s)
- Mihaela Bacalum
- Biomedical Research Institute, Hasselt University , Agoralaan Building C, 3590, Diepenbeek, Belgium
- Department of Life and Environmental Physics, Horia Hulubei National Institute for Physics and Nuclear Engineering , Reactorului 30, Măgurele, 077125, Romania
| | - Lina Wang
- Department of Chemistry, Katholieke Universiteit Leuven (KU Leuven) , Celestijnenlaan 200f - bus 02404, 3001 Leuven, Belgium
| | - Stijn Boodts
- Department of Chemistry, Katholieke Universiteit Leuven (KU Leuven) , Celestijnenlaan 200f - bus 02404, 3001 Leuven, Belgium
| | - Peijia Yuan
- Department of Chemistry, Katholieke Universiteit Leuven (KU Leuven) , Celestijnenlaan 200f - bus 02404, 3001 Leuven, Belgium
| | - Volker Leen
- Department of Chemistry, Katholieke Universiteit Leuven (KU Leuven) , Celestijnenlaan 200f - bus 02404, 3001 Leuven, Belgium
| | - Nick Smisdom
- Biomedical Research Institute, Hasselt University , Agoralaan Building C, 3590, Diepenbeek, Belgium
| | - Eduard Fron
- Department of Chemistry, Katholieke Universiteit Leuven (KU Leuven) , Celestijnenlaan 200f - bus 02404, 3001 Leuven, Belgium
| | - Stefan Knippenberg
- Biomedical Research Institute, Hasselt University , Agoralaan Building C, 3590, Diepenbeek, Belgium
- Division of Theoretical Chemistry and Biology, KTH Royal Institute of Technology, School of Biotechnology , Roslagstullsbacken 15, S-106 91 Stockholm, Sweden
| | - Gabin Fabre
- LCSN-EA1069, Faculté de Pharmacie, Université de Limoges , 2, rue du Dr. Marcland, 87025 Limoges Cedex, France
- Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University , tř. 17 listopadu 12, 771 46 Olomouc, Czech Republic
| | - Patrick Trouillas
- Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University , tř. 17 listopadu 12, 771 46 Olomouc, Czech Republic
- INSERM UMR-S850, Faculté de Pharmacie, Université de Limoges , 2 rue du Docteur Marcland, 87025 Limoges Cedex, France
- Service de Chimie des Matériaux Nouveaux, Université de Mons , Place du Parc 20, B-7000 Mons, Belgium
| | - David Beljonne
- Service de Chimie des Matériaux Nouveaux, Université de Mons , Place du Parc 20, B-7000 Mons, Belgium
| | - Wim Dehaen
- Department of Chemistry, Katholieke Universiteit Leuven (KU Leuven) , Celestijnenlaan 200f - bus 02404, 3001 Leuven, Belgium
| | - Noël Boens
- Department of Chemistry, Katholieke Universiteit Leuven (KU Leuven) , Celestijnenlaan 200f - bus 02404, 3001 Leuven, Belgium
| | - Marcel Ameloot
- Biomedical Research Institute, Hasselt University , Agoralaan Building C, 3590, Diepenbeek, Belgium
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Kahle I, Tröber O, Richter H, Spange S. Synthesis and optical properties of naphthopyran dyes conjugated with fluorescent stilbazolium moieties. NEW J CHEM 2013. [DOI: 10.1039/c3nj41130c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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7
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Malyukin YV, Kavok NS, Borovoi IA, Stepanenko AM, Malyukina MY, Petrukhin PA. A study of the effect of adrenaline on the transmembrane potential of the plasma membrane of hepatocytes from rats of different age using fluorescent probes. Biophysics (Nagoya-shi) 2011. [DOI: 10.1134/s000635091103016x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Synthesis of a new conjugated 2,2′-(1,4-phenylenedivinylene)bis-quinoxaline and a series of styryl derivatives of quinoxaline and quinoline as promising electro- and photoluminescent materials. Chem Heterocycl Compd (N Y) 2009. [DOI: 10.1007/s10593-009-0229-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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9
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Gullapalli RR, Demirel MC, Butler PJ. Molecular dynamics simulations of DiI-C18(3) in a DPPC lipid bilayer. Phys Chem Chem Phys 2008; 10:3548-60. [PMID: 18548161 DOI: 10.1039/b716979e] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We performed a 40 ns simulation of 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI-C18(3)) in a 1,2-dipalmitoyl-sn-glycero-3-phosphatidyl choline (DPPC) bilayer in order to facilitate interpretation of lipid dynamics and membrane structure from fluorescence lifetime, anisotropy, and fluorescence correlations spectroscopy (FCS). Incorporation of DiI of 1.6 to 3.2 mol% induced negligible changes in area per lipid but detectable increases in bilayer thickness, each of which are indicators of membrane structural perturbation. The DiI chromophore angle was 77 +/- 17 degrees with respect to the bilayer normal, consistent with rotational diffusion inferred from polarization studies. The DiI headgroup was located 0.63 nm below the lipid head group-water interface, a novel result in contrast to some popular cartoon representations of DiI but consistent with DiI's increase in quantum yield when incorporated into lipid bilayers. Importantly, the fast component of rotational anisotropy matched published experimental results demonstrating that sufficient free volume exists at the sub-interfacial region to support fast rotations. Simulations with non-charged DiI head groups exhibited DiI flip-flop, demonstrating that the positively-charged chromophore stabilizes the orientation and location of DiI in a single monolayer. DiI induced detectable changes in interfacial properties of water ordering, electrostatic potential, and changes in P-N vector orientation of DPPC lipids. The diffusion coefficient of DiI (9.7 +/- 0.02 x 10(-8) cm2 s(-1)) was similar to the diffusion of DPPC molecules (10.7 +/- 0.04 x 10(-8) cm2 s(-1)), supporting the conclusion that DiI dynamics reflect lipid dynamics. These results provide the first atomistic level insight into DiI dynamics, results essential in elucidating lipid dynamics through single molecule fluorescence studies.
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Affiliation(s)
- Ramachandra R Gullapalli
- Department of Bioengineering, The Pennsylvania State University, 228 Hallowell Building, University Park, PA 16802, USA
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10
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Savtchenko LP, Gogan P, Tyc-Dumont S. Dendritic spatial flicker of local membrane potential due to channel noise and probabilistic firing of hippocampal neurons in culture. Neurosci Res 2001; 41:161-83. [PMID: 11591444 DOI: 10.1016/s0168-0102(01)00274-7] [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: 11/30/2022]
Abstract
Whole-cell recordings and imaging of dissociated hippocampal neurons stained with voltage sensitive dye provide a new microscopic picture of neuronal excitation. This is the first attempt to combine imaging of active channel clusters on the geometry of live neurons and a theoretical approach. During single somatic action potentials and the back-invasion into the neurites, local mean potentials are generated at sites of active channel clusters which are unevenly distributed in the neuronal membrane. Similar mean membrane potentials are observed in the neurites and at the soma. Identical action potentials produce different spatial patterns of mean membrane potentials from trial to trial. This spatial variability is explained by the stochastic behavior of the channels in the clusters. When hippocampal neurons are excited by synaptic inputs, their evoked responses are probabilistic and generate variable spatial patterns of mean membrane potential trial after trial. Our stochastic model reproduces this random behavior by assuming that the voltage fluctuations generated by channel noise are added to the synaptic potentials reaching the soma. We demonstrate that the probability of action potential initiation depends on the strength of the synaptic input, the diameter of the dendrites and the relative positions of the channel clusters, of the synapse and of the soma.
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MESH Headings
- Action Potentials/physiology
- Animals
- Animals, Newborn
- Artifacts
- Cell Communication/physiology
- Cells, Cultured/cytology
- Cells, Cultured/physiology
- Dendrites/physiology
- Dendrites/ultrastructure
- Electric Stimulation
- Electronic Data Processing/instrumentation
- Electronic Data Processing/methods
- Fluorescent Dyes/pharmacokinetics
- Hippocampus/cytology
- Hippocampus/physiology
- Image Processing, Computer-Assisted/instrumentation
- Image Processing, Computer-Assisted/methods
- Ion Channels/physiology
- Microscopy, Video/instrumentation
- Microscopy, Video/methods
- Models, Neurological
- Models, Statistical
- Patch-Clamp Techniques
- Pyramidal Cells/cytology
- Pyramidal Cells/physiology
- Pyridinium Compounds/pharmacokinetics
- Rats
- Rats, Wistar
- Stochastic Processes
- Synapses/physiology
- Synaptic Transmission/physiology
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Affiliation(s)
- L P Savtchenko
- Unité de Neurocybernétique Cellulaire, 280 Bd Sainte Marguerite, 13009 Marseille, France
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Savtchenko LP, Gogan P, Korogod SM, Tyc-Dumont S. Imaging stochastic spatial variability of active channel clusters during excitation of single neurons. Neurosci Res 2001; 39:431-46. [PMID: 11274742 DOI: 10.1016/s0168-0102(01)00196-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Topographical maps of membrane voltages were obtained during action potentials by imaging, at 1 microm resolution, live dissociated neurons stained with the voltage sensitive dye RH237. We demonstrate with a theoretical approach that the spatial patterns in the images result from the distribution of net positive charges condensed in the inner sites of the membrane where clusters of open ionic channels are located. We observed that, in our biological images, this spatial distribution of open channels varies randomly from trial to trial while the action potentials recorded by the microelectrode display similar amplitudes and time-courses. The random differences in size and intensity of the spatial patterns in the images are best evidenced when the time of observation coincides with the duration of single action potentials. This spatial variability is explained by the fact that only part of the channel population generates an action potential and that different channels open in turn in different trials due to their stochastic operation. Such spatial flicker modifies the direction of lateral current along the neuronal membrane and may have important consequences on the intrinsic processing capabilities of the neuron.
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Affiliation(s)
- L P Savtchenko
- International Center for Molecular Physiology (Dniepropetrovsk division), National Academy of Sciences of Ukraine, Research Laboratory of Biophysics and Bioeletronics, Dniepropetrovsk State University, Dniepropetrovsk 49050, Ukraine
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12
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Das TK, Mazumdar S. Effect of Adriamycin on the boundary lipid structure of cytochrome c oxidase: pico-second time-resolved fluorescence depolarization studies. Biophys Chem 2000; 86:15-28. [PMID: 11011696 DOI: 10.1016/s0301-4622(00)00158-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The fluorescence dynamics of the dye 3,3'-diethyloxadicarbocyanine iodide (DODCI) was used to probe the microenvironment of cytochrome c oxidase (CcO) and cardiolipin. The dye was partitioned between an aqueous and a hydrophobic phase. The 'bound' and 'free' populations of DODCI could be separated by analysis of the time-resolved fluorescence decay of the dye. The anisotropy decay of the DODCI bound to CcO showed a unique 'dip and rise' shape that was analyzed by a combination of rotational correlation times with time-dependent weight factors for each lifetime component. Rotational dynamics studies revealed the existence of a restricted motion of the dye bound at the enzyme surface. Adriamycin, an anticancer, albeit cardiotoxic drug, was previously proposed to affect the surface structure of CcO, most likely by causing a disorder to the surface lipid arrangement. A drastic change in the rotational correlation time of the dye bound to the enzyme surface was observed, which suggested a depletion of cardiolipin layer due to complexation with the drug. The effect of Adriamycin on cardiolipin was drastic, leading to its phase separation. The present study suggests that the effect of Adriamycin on CcO is primarily a segregation of the cardiolipins.
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Affiliation(s)
- T K Das
- Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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Binnemans K, Bex C, Venard A, De Leebeeck H, Görller-Walrand C. Solvatochromism of lanthanide complexes containing the hemicyanine chromophore. J Mol Liq 1999. [DOI: 10.1016/s0167-7322(99)00092-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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14
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Sund SE, Swanson JA, Axelrod D. Cell membrane orientation visualized by polarized total internal reflection fluorescence. Biophys J 1999; 77:2266-83. [PMID: 10512845 PMCID: PMC1300506 DOI: 10.1016/s0006-3495(99)77066-9] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
In living cells, variations in membrane orientation occur both in easily imaged large-scale morphological features, and also in less visualizable submicroscopic regions of activity such as endocytosis, exocytosis, and cell surface ruffling. A fluorescence microscopic method is introduced here to visualize such regions. The method is based on fluorescence of an oriented membrane probe excited by a polarized evanescent field created by total internal reflection (TIR) illumination. The fluorescent carbocyanine dye diI-C(18)-(3) (diI) has previously been shown to embed in the lipid bilayer of cell membranes with its transition dipoles oriented nearly in the plane of the membrane. The membrane-embedded diI near the cell-substrate interface can be fluorescently excited by evanescent field light polarized either perpendicular or parallel to the plane of the substrate coverslip. The excitation efficiency from each polarization depends on the membrane orientation, and thus the ratio of the observed fluorescence excited by these two polarizations vividly shows regions of microscopic and submicroscopic curvature of the membrane, and also gives information regarding the fraction of unoriented diI in the membrane. Both a theoretical background and experimental verification of the technique is presented for samples of 1) oriented diI in model lipid bilayer membranes, erythrocytes, and macrophages; and 2) randomly oriented fluorophores in rhodamine-labeled serum albumin adsorbed to glass, in rhodamine dextran solution, and in rhodamine dextran-loaded macrophages. Sequential digital images of the polarized TIR fluorescence ratios show spatially-resolved time-course maps of membrane orientations on diI-labeled macrophages from which low visibility membrane structures can be identified and quantified. To sharpen and contrast-enhance the TIR images, we deconvoluted them with an experimentally measured point spread function. Image deconvolution is especially effective and fast in our application because fluorescence in TIR emanates from a single focal plane.
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Affiliation(s)
- S E Sund
- Biophysics Research Division and Department of Physics, University of Michigan, Ann Arbor, Michigan 48109 USA
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15
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Unfolding pathway of cytochromec oxidase induced by ionic surfactants: Circular dichroism and picosecond time-resolved fluorescence studies. J CHEM SCI 1998. [DOI: 10.1007/bf02871280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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16
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Srivastava A, Krishnamoorthy G. Time-resolved fluorescence microscopy could correct for probe binding while estimating intracellular pH. Anal Biochem 1997; 249:140-6. [PMID: 9212865 DOI: 10.1006/abio.1997.2164] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Estimation of intracellular pH by fluorescence ratiometry overcomes many of the limitations such as variations in the pathlength of observation and concentration of the probe, light scattering, and photobleaching. However, binding of probes to membranes and macromolecules is generally not taken into account. By using time-resolved fluorescence microscopy on a variety of cell types, we have shown that the dual-emission fluorescent pH probe carboxy SNARF-1 binds to cellular components in significant levels. The bound population could be resolved in the timescale since its fluorescence lifetime (approximately 3 ns) is significantly larger than that of the free probe. Intracellular pH was estimated from the relative amplitudes corresponding to free probes. This procedure was validated in simple model systems where carboxy SNARF-1 was present in solutions of bovine serum albumin. It was shown that the intracellular pH could be overestimated by as much as 1 pH unit in the absence of correction for probe binding.
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Affiliation(s)
- A Srivastava
- Chemical Physics Group, Tata Institute of Fundamental Research, Mumbai, India
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17
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Investigation of potential-sensitive fluorescent dyes for application in nitrate sensitive polymer membranes. ACTA ACUST UNITED AC 1997. [DOI: 10.1007/s002160050154] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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18
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Das TK. Rotational Dynamics of Lipid/Detergent Mixtures: A Mechanism for Membrane Protein Reconstitution into Lipid Vesicles. ACTA ACUST UNITED AC 1996. [DOI: 10.1021/jp9608638] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Tapan Kanti Das
- Chemical Physics Group, Tata Institute of Fundamental Research, Homi Bhabha Road, Bombay 400 005, India
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Das TK. Rotational dynamics of lipid–detergent mixtures probed by a cyanine dye: a mechanism for vesicle formation. ACTA ACUST UNITED AC 1996. [DOI: 10.1039/ft9969204279] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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Absence of kinetic barrier for transfer of protons from aqueous phase to membrane-water interface. J Biosci 1995. [DOI: 10.1007/bf02703298] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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21
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Mohr GJ, Wolfbeis OS. Optical sensing of anions via polarity-sensitive dyes: A bulk sensor membrane for nitrate. Anal Chim Acta 1995. [DOI: 10.1016/0003-2670(95)00370-f] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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22
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Time-resolved fluorescence study of the single tryptophan in thiocyanate and azide derivatives of horseradish peroxidase: Implication for apH-induced conformational change in the heme cavity. J CHEM SCI 1995. [DOI: 10.1007/bf02840806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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23
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Das TK, Mazumdar S. pH-induced conformational perturbation in horseradish peroxidase. Picosecond tryptophan fluorescence studies on native and cyanide-modified enzymes. EUROPEAN JOURNAL OF BIOCHEMISTRY 1995; 227:823-8. [PMID: 7867643 DOI: 10.1111/j.1432-1033.1995.tb20207.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The fluorescence-decay characteristics of the single tryptophan present in horseradish peroxidase (HRP) have been studied using dye-laser pulses and single-photon counting techniques. The decay was found to be dominated by a picosecond-lifetime component, with small contributions from two other lifetime components in the nanosecond range. The distance of the tryptophan residue was estimated from the fluorescence-energy transfer to the heme moiety using Förster's theory. The tryptophan residue was found to be approximately 1.2 nm from the heme moiety at neutral pH. Detailed analysis of the fluorescence-decay profiles using the maximum-entropy method (MEM) has been carried out. The results of the MEM analysis also showed a maximum amplitude peak at approximately 45 ps (at pH approximately 7) with a very small (< 5%) contribution from two other components. Similar results were obtained with the cyanide derivative of the enzyme (HRPCN) where the major lifetime component was found to be 58 ps at neutral pH. The picosecond component of fluorescence lifetimes of native HRP as well as of HRPCN were found to increase with decrease in pH in the range pH 6-3.5. Moreover, the native enzyme showed significant increase in the magnitude of this fast lifetime component at pH above 8. Such increase in the major lifetime component possibly indicated a conformational perturbation caused by pH change in the enzyme. However, the pH dependence of HRPCN, which is devoid of alkaline transition, showed that the shortest lifetime component remains almost unchanged over the pH range 6-11. This result showed that the alkaline transition in native HRP is associated with a structural change in the distal region of the heme center, which is absent in the cyanide-ligated enzyme. The results have been discussed with respect to understanding the pH-induced effects associated with salt bridge and hydrogen-bonding network in HRP.
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Affiliation(s)
- T K Das
- Chemical Physics Group, Tata Institute of Fundamental Research, Bombay, India
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Das TK, Mazumdar S. Conformational change due to reduction of cytochrome-c oxidase in lauryl maltoside: picosecond time-resolved tryptophan fluorescence studies on the native and heat modified enzyme. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1209:227-37. [PMID: 7811695 DOI: 10.1016/0167-4838(94)90189-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Detailed fluorescence studies on bovine heart cytochrome-c oxidase (CcO) has been carried out in lauryl maltoside solution. Steady-state fluorescence of the tryptophan residues of the enzyme showed that the fluorophores are embedded deep inside the hydrophobic protein cavity. Time resolved studies of tryptophan fluorescence of native and heat treated CcO have been carried out in both reduced and oxidised forms using synchronously pumped pulsed picosecond dye laser and single photon counting technique. Decay of the tryptophan fluorescence have been fitted using discrete four exponential model. Amplitude distribution of lifetimes also showed four distinct regions in the analysis of the decay profiles by maximum entropy method (MEM). The results indicate that controlled heat treatment of CcO affects the conformation of the enzyme near the active centers which makes it incapable of active proton pumping while the electron transfer property is still conserved. Reduction of the native CcO is associated with a large conformation change in lauryl maltoside near the active centers which is not observed in case of CcO encapsulated in vesicles. Reduction of the heat treated enzyme was found to have a conformation different from the reduced native CcO.
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Affiliation(s)
- T K Das
- Chemical Physics Group, Tata Institute of Fundamental Research, Colaba, Bombay, India
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Ahmed I, Krishnamoorthy G. Anomalous response of oxonol-V to membrane potential in mitochondrial proton pumps. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1188:131-8. [PMID: 7947900 DOI: 10.1016/0005-2728(94)90031-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The response of the fluorescent membrane potential probe oxonol-V (bis[3-phenyl 5 oxoisoxazol-4-yl]pentamethine oxonol) in submitochondrial particles (SMP) was dependent upon whether the potential (inside positive) was generated by active proton pumps or by valinomycin-aided passive K+ influx. The fluorescence intensity showed a decrease in the former case and an increase in the latter situation. This anomalous behavior was not observed with other similar anionic probes. Gradual inhibition of proton pumping activity showed that the difference in the response of oxonol-V is not due to possible difference in the magnitude of membrane potential generated in these two situations. In the presence of membrane permeant anions such as TPB- (tetraphenyl boron) or chlorate, the direction of response of oxonol-V fluorescence was the same in both situations. Time-resolved fluorescence of the oxonol-V-SMP system showed three populations: one free form (fluorescence lifetime approximately 60 ps) and two SMP-bound forms (lifetimes of 0.45 ns and 1.4 ns). A fourth population was created during the action of proton pumps. The shorter lifetime (approximately 250 ps) of this new bound form suggest this population to be an aggregated form. This population was absent during the action of proton pumps in the presence of TPB- or chlorate. These results suggest the creation of a charge separated state during the action of proton pumps. The decrease in fluorescence intensity could be the result of aggregation of oxonol-V around the positive end of a proton pump existing in a dipole or charge separated state.
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Affiliation(s)
- I Ahmed
- Chemical Physics Group, Tata Institute of Fundamental Research, Bombay, India
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Epps DE, Wolfe ML, Groppi V. Characterization of the steady-state and dynamic fluorescence properties of the potential-sensitive dye bis-(1,3-dibutylbarbituric acid)trimethine oxonol (Dibac4(3)) in model systems and cells. Chem Phys Lipids 1994; 69:137-50. [PMID: 8181103 DOI: 10.1016/0009-3084(94)90035-3] [Citation(s) in RCA: 156] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The steady-state and dynamic fluorescence properties of the membrane potential-sensitive bis-oxonol dye Dibac4(3) were characterized in vitro using model ligand systems and in vivo in A10 smooth muscle cells by fluorescence microscopy in conjunction with the ACAS imaging system. In the latter system the dye responds to potassium ion-induced jumps in membrane potential with changes in its fluorescence intensity, which follow pseudo-first-order kinetics. The relationship between the magnitude of the changes and the corresponding rate constants excludes the possibility that a simple, one-step equilibrium between extracellular and cytoplasmic dye would be sufficient to account for this phenomenon. The necessity of invoking an additional step suggested that the redistribution of the free dye between the cytoplasm and the exocellular medium is rapid and that the slow step associated with the fluorescence changes may be the interaction of the dye with proteins in the cytoplasm, along the lines proposed by Bräuner et al. (Biochim. Biophys. Acta 771 (1984), 208, 216). The interaction of the dye with BSA and with egg lecithin SUVs was studied as a model for the in vivo phenomenon. The dependence of fluorescence intensity changes on the concentrations of the reagents shows the formation of a reversible dye/albumin complex with a 2/1-stoichiometry, with Kd = 0.03 +/- 0.01 microM and a reversible adsorption to the SUVs with Kd 0.45 +/- 0.08 microM. The fluorescence lifetime of the dye in solution, < 100 ps, results in a high solution steady-state anisotropy. The latter decreases considerably upon binding to BSA, SUVs and A10 cells concomitant with a large increase in the lifetime. With such a short lifetime of the free dye, selective gating of the excitation source or the photodetector should eliminate the high background of the unbound dye and thereby enhance the sensitivity of the system.
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Affiliation(s)
- D E Epps
- Upjohn Company, Kalamazoo, MI 49001-0199
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