1
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Ashworth EK, Langeland J, Stockett MH, Lindkvist TT, Kjær C, Bull JN, Nielsen SB. Cryogenic Fluorescence Spectroscopy of Ionic Fluorones in Gaseous and Condensed Phases: New Light on Their Intrinsic Photophysics. J Phys Chem A 2022; 126:9553-9563. [PMID: 36529970 DOI: 10.1021/acs.jpca.2c07231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Fluorescence spectroscopy of gas-phase ions generated through electrospray ionization is an emerging technique able to probe intrinsic molecular photophysics directly without perturbations from solvent interactions. While there is ample scope for the ongoing development of gas-phase fluorescence techniques, the recent expansion into low-temperature operating conditions accesses a wealth of data on intrinsic fluorophore photophysics, offering enhanced spectral resolution compared with room-temperature measurements, without matrix effects hindering the excited-state dynamics. This perspective reviews current progress on understanding the photophysics of anionic fluorone dyes, which exhibit an unusually large Stokes shift in the gas phase, and discusses how comparison of gas- and condensed-phase fluorescence spectra can fingerprint structural dynamics. The capacity for temperature-dependent measurements of both fluorescence emission and excitation spectra helps establish the foundation for the use of fluorone dyes as fluorescent tags in macromolecular structure determination. We suggest ideas for technique development.
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Affiliation(s)
- Eleanor K Ashworth
- School of Chemistry, University of East Anglia, NorwichNR4 7TJ, United Kingdom
| | - Jeppe Langeland
- Department of Physics and Astronomy, Aarhus University, Aarhus8000, Denmark
| | - Mark H Stockett
- Department of Physics, Stockholm University, SE-10691Stockholm, Sweden
| | | | - Christina Kjær
- Department of Physics and Astronomy, Aarhus University, Aarhus8000, Denmark
| | - James N Bull
- School of Chemistry, University of East Anglia, NorwichNR4 7TJ, United Kingdom
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2
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Asami H, Kawauchi N, Kohno JY. Gas-phase hydration of the lysozyme ion produced by infrared-laser ablation of a droplet beam studied by photodissociation and fluorescence spectroscopy. JOURNAL OF MASS SPECTROMETRY : JMS 2021; 56:e4620. [PMID: 32721078 DOI: 10.1002/jms.4620] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 07/06/2020] [Accepted: 07/08/2020] [Indexed: 06/11/2023]
Abstract
Biomolecules function in an aqueous environment. Elucidation of the hydration structures of biomolecules is hence important to understand their functions. Here, we investigated the hydration structure of lysozyme (Lys) in the gas phase by photodissociation and fluorescence spectroscopy in combination with droplet-beam laser ablation mass spectrometry. We found that water molecules are held inside and on the surface of the Lys molecule, and the hydration structure around the tryptophan residue changes by photoexcitation. This study provides a novel method to observe the hydration structures of large biomolecules at the molecular level.
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Affiliation(s)
- Hiroya Asami
- Department of Chemistry, Faculty of Science, Gakushuin University, Tokyo, Japan
| | - Norishi Kawauchi
- Department of Chemistry, Faculty of Science, Gakushuin University, Tokyo, Japan
| | - Jun-Ya Kohno
- Department of Chemistry, Faculty of Science, Gakushuin University, Tokyo, Japan
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3
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Szarka M, Szigeti M, Guttman A. Imaging Laser-Induced Fluorescence Detection at the Taylor Cone of Electrospray Ionization Mass Spectrometry. Anal Chem 2019; 91:7738-7743. [DOI: 10.1021/acs.analchem.9b01028] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Máte Szarka
- Horváth Csaba Memorial Laboratory of Bioseparation Sciences, Research Center for Molecular Medicine, Faculty of Medicine, University of Debrecen, 98 Nagyerdei krt, Debrecen 4032, Hungary
| | - Márton Szigeti
- Horváth Csaba Memorial Laboratory of Bioseparation Sciences, Research Center for Molecular Medicine, Faculty of Medicine, University of Debrecen, 98 Nagyerdei krt, Debrecen 4032, Hungary
- Translational Glycomics Laboratory, Research Institute of Biomolecular and Chemical Engineering, University of Pannonia, 10 Egyetem Street, Veszprem 8200, Hungary
| | - András Guttman
- Horváth Csaba Memorial Laboratory of Bioseparation Sciences, Research Center for Molecular Medicine, Faculty of Medicine, University of Debrecen, 98 Nagyerdei krt, Debrecen 4032, Hungary
- Translational Glycomics Laboratory, Research Institute of Biomolecular and Chemical Engineering, University of Pannonia, 10 Egyetem Street, Veszprem 8200, Hungary
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4
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Quanten T, De Mayaer T, Shestakova P, Parac-Vogt TN. Selectivity and Reactivity of Zr IV and Ce IV Substituted Keggin Type Polyoxometalates Toward Cytochrome c in Surfactant Solutions. Front Chem 2018; 6:372. [PMID: 30211153 PMCID: PMC6121075 DOI: 10.3389/fchem.2018.00372] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 08/02/2018] [Indexed: 12/15/2022] Open
Abstract
In this paper we investigate the effect of three different types of surfactants, on the hydrolysis of Cytochrome c (Cyt c), a predominantly α helical protein containing a heme group, promoted by [Ce(α PW11O39)2]10- (CeK) and [Zr(α PW11O39)2]10- (ZrK) polyoxometalates. In the presence of SDS, Zw3 12, or CHAPS surfactants, which are commonly used for solubilizing hydrophobic proteins, the specificity of CeK or ZrK toward hydrolysis of Cyt c does not change. However, the hydrolysis rate of Cyt c by CeK was increased in the presence of SDS, but decreased in the presence of CHAPS, and was nearly inhibited in the presence of Zw3 12. The Circular dichroism and Tryptophan fluorescence spectroscopy have shown that the structural changes in Cyt c caused by surfactants are similar to those caused by POMs, hence the same specificity in the absence or presence of surfactants was observed. The results also indicate that for Cyt c hydrolysis to occur, large unfolding of the protein is needed in order to accommodate the POMs. While SDS readily unfolds Cyt c, the protein remains largely folded in the presence of CHAPS and Zw3 12. Addition of POMs to Cyt c solutions in CHAPS results in unfolding of the structure allowing the interaction with POMs to occur and results in protein hydrolysis. Zw3 12, however, locks Cyt c in a conformation that resists unfolding upon addition of POM, and therefore results in nearly complete inhibition of protein hydrolysis.
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Affiliation(s)
- Thomas Quanten
- Laboratory of Bio-Inorganic Chemistry, Department of Chemistry, KU Leuven, Leuven, Belgium
| | - Tessa De Mayaer
- Laboratory of Bio-Inorganic Chemistry, Department of Chemistry, KU Leuven, Leuven, Belgium
| | - Pavletta Shestakova
- NMR Centre, Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Tatjana N Parac-Vogt
- Laboratory of Bio-Inorganic Chemistry, Department of Chemistry, KU Leuven, Leuven, Belgium
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5
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Das S, Pal U, Chandra Maiti N. Metal ions provide structural stability and compactness to tetrameric purothionin. RSC Adv 2016. [DOI: 10.1039/c6ra16576a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Metal ions impart structural stability to the purothionin tetramer.
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Affiliation(s)
- Swagata Das
- Structural Biology & Bioinformatics Division
- CSIR-Indian Institute of Chemical Biology
- Kolkata 700032
- India
| | - Uttam Pal
- Structural Biology & Bioinformatics Division
- CSIR-Indian Institute of Chemical Biology
- Kolkata 700032
- India
| | - Nakul Chandra Maiti
- Structural Biology & Bioinformatics Division
- CSIR-Indian Institute of Chemical Biology
- Kolkata 700032
- India
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6
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Gibson SC, Feigerle CS, Cook KD. Fluorometric Measurement and Modeling of Droplet Temperature Changes in an Electrospray Plume. Anal Chem 2013; 86:464-72. [DOI: 10.1021/ac402364g] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Stephen C. Gibson
- Department
of Chemistry, University of Tennessee, 552 Buehler Hall, 1420 Circle Drive, Knoxville, Tennessee 37996-1600, United States
| | - Charles S. Feigerle
- Department
of Chemistry, University of Tennessee, 552 Buehler Hall, 1420 Circle Drive, Knoxville, Tennessee 37996-1600, United States
| | - Kelsey D. Cook
- Department
of Chemistry, University of Tennessee, 552 Buehler Hall, 1420 Circle Drive, Knoxville, Tennessee 37996-1600, United States
- National Science Foundation, 4201
Wilson Boulevard, Arlington, Virginia 22230, United States
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7
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Brunet C, Antoine R, Lemoine J, Dugourd P. Soret Band of the Gas-Phase Ferri-Cytochrome c. J Phys Chem Lett 2012; 3:698-702. [PMID: 26286275 DOI: 10.1021/jz300070r] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report the first visible spectrum of a heme-protein in the gas phase. The aim of this work was to provide a reference for the optical absorption of an isolated heme-protein to better understand the influence of protein conformation and fluctuation and of solvent on its optical properties. After laser irradiation of gas-phase cytochrome c (cyt c), electron emission is observed. Electron photodetachment yield of cyt c 6- was recorded in the region of the Soret band of the porphyrin group, showing a maximum at 410 nm. Our results are compared with optical spectra of gas-phase heme and of cyt c in solution. We discuss the influence of the polypeptide chain and of the solvent on both the position and the broadening of the Soret band. Action spectrum of gas-phase cyt c is close to the absorption of native cyt c in solution, suggesting an efficient protection of the heme group from solvent accessibility by the polypeptide chain and similar interactions between the two moieties in solution and the gas phase.
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Affiliation(s)
- Claire Brunet
- †Université Lyon 1, Lyon, France
- ‡CNRS, LASIM UMR 5579, 43 bd du 11 novembre 1918, 69622 Villeurbanne Cedex, France
- §CNRS, Institut des Sciences Analytique UMR 5180, 43 bd du 11 novembre 1918, 69622 Villeurbanne Cedex, France
| | - Rodolphe Antoine
- †Université Lyon 1, Lyon, France
- ‡CNRS, LASIM UMR 5579, 43 bd du 11 novembre 1918, 69622 Villeurbanne Cedex, France
| | - Jérôme Lemoine
- †Université Lyon 1, Lyon, France
- §CNRS, Institut des Sciences Analytique UMR 5180, 43 bd du 11 novembre 1918, 69622 Villeurbanne Cedex, France
| | - Philippe Dugourd
- †Université Lyon 1, Lyon, France
- ‡CNRS, LASIM UMR 5579, 43 bd du 11 novembre 1918, 69622 Villeurbanne Cedex, France
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8
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Girod M, Dagany X, Boutou V, Broyer M, Antoine R, Dugourd P, Mordehai A, Love C, Werlich M, Fjeldsted J, Stafford G. Profiling an electrospray plume by laser-induced fluorescence and Fraunhofer diffraction combined to mass spectrometry: influence of size and composition of droplets on charge-state distributions of electrosprayed proteins. Phys Chem Chem Phys 2012; 14:9389-96. [DOI: 10.1039/c2cp23341j] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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9
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Electrospray ionization mass spectrometry: a technique to access the information beyond the molecular weight of the analyte. Int J Anal Chem 2011; 2012:282574. [PMID: 22611397 PMCID: PMC3348530 DOI: 10.1155/2012/282574] [Citation(s) in RCA: 268] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Revised: 10/23/2011] [Accepted: 11/09/2011] [Indexed: 01/12/2023] Open
Abstract
The Electrospray Ionization (ESI) is a soft ionization technique extensively used for production of gas phase ions (without fragmentation) of thermally labile large supramolecules. In the present review we have described the development of Electrospray Ionization mass spectrometry (ESI-MS) during the last 25 years in the study of various properties of different types of biological molecules. There have been extensive studies on the mechanism of formation of charged gaseous species by the ESI. Several groups have investigated the origin and implications of the multiple charge states of proteins observed in the ESI-mass spectra of the proteins. The charged analytes produced by ESI can be fragmented by activating them in the gas-phase, and thus tandem mass spectrometry has been developed, which provides very important insights on the structural properties of the molecule. The review will highlight recent developments and emerging directions in this fascinating area of research.
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10
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Characterization of Rhodamine 6G Release in Electrospray Ionization by Means of Spatially Resolved Fluorescence Spectroscopy. Z PHYS CHEM 2011. [DOI: 10.1524/zpch.2011.0149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
In the present work, the density distribution of rhodamine 6G ions (R6G) in the gas phase and the droplets of an electrospray plume was studied by spatial and spectral imaging. The intention is to contribute to the fundamental understanding of the release mechanism of gaseous R6G in the electrospray ionization (ESI) process. Furthermore, the influence of ESI-parameters on the release efficiency of R6G, e.g. solvent flow, R6G and salt concentration were examined via direct fluorescence imaging of R6G. A solvent-shift of the fluorescence maximum, λ
max = 555 nm in methanolic solution and λ
max = 505 nm in gas phase, allows the discrimination between solvated and gaseous R6G. Two experimental setups were used for our measurements. In the first experiment, the R6G fluorescence and the light scattered from the spray plume were imaged in two spatial dimensions using a tunable wavelength fil ter. The second experiment was designed for obtaining 1-dimensional spatially resolved emission spectra of the spray. Here, the intensity distribution of solvated and gaseous R6G as well as scattered light (λ=355 nm) were measured simultaneously.
The results show the distribution of gaseous R6G in the plane, orthogonal to the ESI capillary, decreasing slightly towards the spray center and showing maxima at the cone margins. The distribution of gaseous R6G confirms the preferred release of gaseous ions from nano-droplets, indicating the ion evaporation model (IEM) to be the dominating release mechanism. Up to now, only a few fluorescence spectra of ionic compounds in the gas phase were published because the measurement of emission spectra of mass-selected ions in an ion trap is experimentally challenging. The fluorescence spectrum of gaseous lucigenin at atmospheric pressure is reported for the first time. This spectrum of lucigenin in the gas phase exhibits a blue shift of about Δλ=10 nm in comparison to the corresponding spectrum in methanol.
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11
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Banerjee S, Prakash H, Mazumdar S. Evidence of molecular fragmentation inside the charged droplets produced by electrospray process. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2011; 22:1707-1717. [PMID: 21952884 DOI: 10.1007/s13361-011-0188-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Revised: 06/03/2011] [Accepted: 06/05/2011] [Indexed: 05/31/2023]
Abstract
The behavior of the analyte molecules inside the neutral core of the charged droplet produced by the electrospray (ES) process is not unambiguously known to date. We have identified interesting molecular transformations of two suitably chosen analytes inside the ES droplets. The highly stable Ni(II) complex of 1,8-dimethyl-1,3,6,8,10,13-hexaazacyclotetradecane (1) that consists of a positive charge at the metal center, and the allyl pendant armed tertiary amine containing macrocycle 3,4,5:12,13,14-dipyridine-2,6,11,15-tetramethyl-1,7,10,16-tetraallyl-1,4,7,10,13,16-hexaazacyclooctadeca-3,13-diene (M(4p)) have been studied by ESI mass spectrometry as the model analytes. We have shown that these two molecules are not representatively transferred from solution to gas phase by ESI; rather, they undergo fragmentation inside the charged droplets. The results indicated that a charged analyte such as 1 was possibly unstable inside the neutral core of the ES droplet and undergoes fragmentation due to the Coulombic repulsion imparted by the surface protons. Brownian motion of the neutral analyte such as M(4p) inside the droplet, on the other hand, may lead to proton attachment on interaction with the charged surface causing destabilization that leads to fragmentation of M(4p) and release of resonance stabilized allyl cations from the core of the droplet. Detailed solvent dependence and collision-induced dissociation (CID) studies provided compelling evidences that the fragmentation of the analytes indeed occurs inside the charged ES droplets. A viable model of molecular transformations inside the ES droplet was proposed based on these results to rationalize the behavior of the analyte molecules inside the charged ES droplets.
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Affiliation(s)
- Shibdas Banerjee
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
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12
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Wei W, Danielson ND. Fluorescence and circular dichroism spectroscopy of cytochrome c in alkylammonium formate ionic liquids. Biomacromolecules 2011; 12:290-7. [PMID: 21210672 DOI: 10.1021/bm1008052] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The structural stability of cytochrome c has been studied in alkylammonium formate (AAF) ionic liquids such as methylammonium formate (MAF) and ethylammonium formate (EAF) by fluorescence and circular dichroism (CD) spectroscopy. At room temperature, the native structure of cytochrome c is maintained in relatively high ionic liquid concentrations (50-70% AAF/water or AAF/phosphate buffer pH 7.0) in contrast with denaturation of cytochrome c in similar solutions of methanol or acetonitrile with water or buffer cosolvents. Fluorescence and CD spectra indicate that the conformation of cytochrome c is maintained in 20% AAF-80% water from 30 to 50 °C. No such temperature stability is found in 80% AAF-20% water. About one-third of the enzyme activity of cytochrome c in 80% AAF-20% water can be maintained as compared with phosphate buffer, and this is greater than the activities measured in corresponding methanol and acetonitrile aqueous solutions. This biophysical study shows that AAFs have potential application as organic solvent replacements at moderate temperature in the mobile phase for the separation of proteins in their native form by reversed phase liquid chromatography.
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Affiliation(s)
- Wenjun Wei
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, USA
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13
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Fang Y, Bennett A, Liu J. Selective transport of amino acids into the gas phase: driving forces for amino acid solubilization in gas-phase reverse micelles. Phys Chem Chem Phys 2011; 13:1466-78. [DOI: 10.1039/c0cp00823k] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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Rizzo TR, Stearns JA, Boyarkin OV. Spectroscopic studies of cold, gas-phase biomolecular ions. INT REV PHYS CHEM 2009. [DOI: 10.1080/01442350903069931] [Citation(s) in RCA: 242] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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15
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Guo C, Wu X, Xu W, Yang J. Resonance light-scattering enhancement effect of the protein-Y3+-TTA-SLS system and its analytical application. LUMINESCENCE 2008; 23:404-9. [DOI: 10.1002/bio.1053] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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16
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Wortmann A, Kistler-Momotova A, Zenobi R, Heine MC, Wilhelm O, Pratsinis SE. Shrinking droplets in electrospray ionization and their influence on chemical equilibria. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2007; 18:385-93. [PMID: 17112736 DOI: 10.1016/j.jasms.2006.10.010] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2006] [Revised: 10/03/2006] [Accepted: 10/11/2006] [Indexed: 05/12/2023]
Abstract
We investigated how chemical equilibria are affected by the electrospray process, using simultaneous in situ measurements by laser-induced fluorescence (LIF) and phase Doppler anemometry (PDA). The motivation for this study was the increasing number of publications in which electrospray ionization mass spectrometry is used for binding constant determination. The PDA was used to monitor droplet size and velocity, whereas LIF was used to monitor fluorescent analytes within the electrospray droplets. Using acetonitrile as solvent, we found an average initial droplet diameter of 10 microm in the electrospray. The PDA allowed us to follow the evolution of these droplets down to a size of 1 microm. Rhodamine B-sulfonylchloride was used as a fluorescent analyte within the electrospray. By spatially resolved LIF it was possible to probe the dimerization equilibrium of this dye. Measurements at different spray positions showed no influence of the decreasing droplet size on the monomer-dimer equilibrium. However, with the fluorescent dye pair DCM and oxazine 1 it was shown that a concentration increase does occur within electrosprayed droplets, using fluorescence resonance energy transfer as a probe for the average pair distance.
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Affiliation(s)
- Arno Wortmann
- Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland
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17
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Samalikova M, Grandori R. Testing the role of solvent surface tension in protein ionization by electrospray. JOURNAL OF MASS SPECTROMETRY : JMS 2005; 40:503-510. [PMID: 15712370 DOI: 10.1002/jms.821] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
This work was aimed at probing the influence of solvent surface tension on protein ionization by electrospray. In particular, we were interested in testing the previously suggested hypothesis that the charge-state distributions (CSDs) of proteins in electrospray ionization mass spectrometry (ESI-MS) are controlled by the surface tension of the least volatile solvent component. In the attempt to minimize uncontrolled conformational effects, we used acid-sensitive proteins (cytochrome c and myoglobin) at low pH or highly stable proteins (ubiquitin and lysozyme) in the presence of low concentrations of organic solvents. A first set of experiments compared the effect of 1- and 2-propanol. These two alcohols have similar chemico-physical properties but values of vapor pressure below and above that of water, respectively. Both compounds have much lower surface tension than water. The solvents employed allowed testing of the influence of surface tension on protein spectra obtained from similarly denaturing solutions. The compared solvent conditions gave rise to very similar spectra for each tested protein. We then investigated the effect of the addition of dimethyl sulfoxide to acid-unfolded proteins. We observed enhanced ionization in the presence of acetic or formic acid, consistent with the previously described supercharging effect, but almost no shift of the CSD in the presence of HCl. Finally, we analyzed thermally denatured cytochrome c, to obtain reference spectra of the unfolded protein in high-surface-tension solutions. Also in this case, the CSD of the unfolded protein was shifted towards lower m/z values relative to low-surface-tension systems. In contrast to the other results reported here, this effect is consistent with an influence of solvent surface tension on CSD. The magnitude of the effect, however, is much smaller than predicted by the Rayleigh equation. The results presented here are not easy to reconcile with the hypothesis that the maximum charge state exhibited by proteins in ESI-MS reflects the Rayleigh-limit charge of the precursor droplet. The data are discussed with reference to models for the mechanism of electrospray ionization.
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Affiliation(s)
- Maria Samalikova
- Institute of Organic Chemistry, Johannes-Kepler University, Altenbergerstrasse 69, A-4040 Linz, Austria
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18
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Liu Y, Yang J, Liu S, Wu X, Su B, Wu T. Resonance light scattering technique for the determination of protein with rutin and cetylpyridine bromide system. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2005; 61:641-646. [PMID: 15649795 DOI: 10.1016/j.saa.2004.05.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2004] [Accepted: 05/17/2004] [Indexed: 05/24/2023]
Abstract
A new resonance light scattering (RLS) assay of protein is presented. In Tris-NaOH (pH = 10.93) buffer, the RLS of rutin-cetylpyridine bromide (CPB) system can be greatly enhanced by protein, including bovine serum albumin (BSA) and human serum albumin (HSA). The enhanced RLS intensities are in proportion to the concentration of proteins in the range of 5 x 10(-9) to 2.5 x 10(-6) g ml(-1) for BSA and 2.5 x 10(-8) to 3.5 x 10(-6) g ml(-1) for HSA. The detection limits (S/N = 3) are 3.0 ng ml(-1) for BSA and 10.0 ng ml(-1) for HSA. Samples are determined satisfactorily.
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Affiliation(s)
- Yang Liu
- Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, PR China
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19
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Youhnovski N, Matecko I, Samalikova M, Grandori R. Characterisation of cytochrome c unfolding by nano-electrospray ionization time-of-fight and Fourier transform ion cyclotron resonance mass spectrometry. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2005; 11:519-24. [PMID: 16322658 DOI: 10.1255/ejms.730] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Protein charge-state distributions (CSDs) in electrospray-ionization mass spectrometry (ESI-MS) represent a sensitive tool to probe different conformational states. We describe here the effect of trifluoroethanol (TFE) on cytochrome c equilibrium unfolding at different pH by nano-ESI-MS. While even low concentrations of TFE destabilize the protein native structure at low pH, a TFE content of 2.5%-5% is found to favor cyt c folding at pH approximately 7. Furthermore, we perform comparison of CSDs obtained by time-of-flight (ToF) and Fourier-transform-ion- cyclotron-resonance (FT-ICR) mass analyzers. To this purpose, we analyze spectra of cyt c in the presence of different kind of denaturants. In particular, experiments with 1-propanol suggest that also by FT-ICR-MS, as previously observed on an ESI-ToF instrument, CSDs do not appear to be controlled by the solvent surface tension as predicted by the Rayleigh-charge model. Moreover, there is general good agreement in conformational effects revealed by the different instruments under several buffer conditions. Nevertheless, the ToF instrument appears to discriminate better between unfolded and partially unfolded forms.
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Affiliation(s)
- Nikolay Youhnovski
- Department of Chemistry, Laboratory of Analytical Chemistry, University of Konstanz, 78457 Konstanz, Germany
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20
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Liu S, Yang J, Wu X, Wang F, Wang F, Jia Z, Mao L. Study on the interaction between protein and Eu(III)-chlorotetracycline complex and the determination of protein using the ?uorimetric method. LUMINESCENCE 2004; 19:352-7. [PMID: 15558687 DOI: 10.1002/bio.792] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Chlorotetracycline (CTC) can react with europium ions Eu3+, and the complex emits the intrinsic fluorescence of Eu3+. The intensity is greatly enhanced by proteins and this forms the basis of a new fluorimetric method for determination of protein. Further research indicates that under optimum conditions, the enhanced intensity of fluorescence is in proportion to the concentration of proteins, in the range 2.0 x 10(-7)-1.0 x 10(-5) g/mL for bovine serum albumin (BSA) (linear equation, I(f) = 34.35933 + 11.54467 x 10(6)C)(r = 0.99895) and 8.0 x 10(-7)-1.0 x 10(-5) g/mL for human serum albumin (HSA) (linear equation, I(f) = 76.58881 + 5.3569 x 10(6)C) (r = 0.99283). Detection limits (S/N = 3) were 8.9 x 10(-9) g/mL for BSA and 3.3 x 10(-8) g/mL for HSA. In an assay for BSA in calf serum, this method gave a value close to that determined by the UV spectrophotometric method.
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Affiliation(s)
- Shufang Liu
- Key Laboratory of Colloid and Interface Chemistry (Shandong University), Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, People's Republic of China
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Bibliography. Current literature in mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2001; 36:1241-1248. [PMID: 11747122 DOI: 10.1002/jms.98] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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