The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Graham Robert Cooks - One of the best experts on this subject based on the ideXlab platform.
-
ion soft landing into Liquids protein identification separation and purification with retention of biological activity
Journal of the American Society for Mass Spectrometry, 2004Co-Authors: Bogdan Gologan, Jormarie Alvarez, Zoltan Takats, Justin M Wiseman, Nari Talaty, Zheng Ouyang, Graham Robert CooksAbstract:Protein ions, after mass spectrometric separation, can be soft-landed into Liquid Surfaces with preservation of their native structures. Retention of biological activity is strongly favored in glycerol-based Surfaces but not in self-assembled monolayer solid Surfaces. Soft-landing efficiency for multiply-charged hexokinase ions was found to be some four times higher for a glycerol/fructose Liquid surface than for a fluorinated self-assembled monolayer surface. Soft-landing into Liquid Surfaces is also shown to allow (1) protein purification, (2) on-surface identification of the soft-landed material using MALDI, and (3) protein identification by in-surface tryptic digestion. Pure lysozyme was successfully isolated from different mixtures including an oxidized, partially decomposed batch of the protein and a partial tryptic digest. Liquid glycerol/carbohydrate mixtures could be used directly to record MALDI spectra on the soft-landed compounds provided they were fortified in advance with traditional MALDI matrices such as p-nitroaniline and α-cyano-4-hydroxycinnamic acid. Various proteins were soft-landed and detected on-target using these types of Liquid surface. Soft-landing of multiply-charged lysozyme ions onto fluorinated self-assembled monolayer Surfaces was found to occur with a limited amount of neutralization, and trapped multiply-charged ions could be desorbed from the surface by laser desorption. Initial data is shown for a new approach to protein identification that combines top-down and bottom-up approaches by utilizing protein ion soft-landing from a protein mixture, followed by tryptic digestion of the landed material and detection of characteristic tryptic fragments by MALDI.
-
preparing protein microarrays by soft landing of mass selected ions
Science, 2003Co-Authors: Zheng Ouyang, Bogdan Gologan, Zoltan Takats, Justin M Wiseman, Thomas A Blake, Andy J Guymon, Justin C Oliver, Jo V Davisson, Graham Robert CooksAbstract:Intact, multiply protonated proteins of particular mass and charge were selected from ionized protein mixtures and gently landed at different positions on a surface to form a microarray. An array of cytochrome c, lysozyme, insulin, and apomyoglobin was generated, and the deposited proteins showed electrospray ionization mass spectra that matched those of the authentic compounds. Deposited lysozyme and trypsin retained their biological activity. Multiply charged ions of protein kinase A catalytic subunit and hexokinase were also soft-landed into glycerol-based Liquid Surfaces. These soft-landed kinases phosphorylated LRRASLG oligopeptide and D-fructose, respectively.
Pulak Dutta - One of the best experts on this subject based on the ideXlab platform.
-
Surface order in cold Liquids: X-ray reflectivity studies of dielectric Liquids and comparison to Liquid metals
Physical Review B, 2010Co-Authors: Sudeshna Chattopadhyay, Benjamin Stripe, Evguenia A. Karapetrova, Ahmet Uysal, Steven N. Ehrlich, Pulak DuttaAbstract:Oscillatory surface-density profiles layers have previously been reported in several metallic Liquids, one dielectric Liquid, and in computer simulations of dielectric Liquids. We have now seen surface layers in two other dielectric Liquids, pentaphenyl trimethyl trisiloxane, and pentavinyl pentamethyl cyclopentasiloxane. These layers appear below T?285 K and T?130 K, respectively; both thresholds correspond to T/Tc?0.2 where Tc is the Liquid-gas critical temperature. All metallic and dielectric Liquid Surfaces previously studied are also consistent with the existence of this T/Tc threshold, first indicated by the simulations of Chacon et al. The layer width parameters, determined using a distorted-crystal fitting model, follow common trends as functions of Tc for both metallic and dielectric Liquids.
-
Surface order in cold Liquids: X-ray reflectivity studies of dielectric Liquids and comparison to Liquid metals
Physical Review B - Condensed Matter and Materials Physics, 2010Co-Authors: Sudeshna Chattopadhyay, Benjamin Stripe, Steven Ehrlich, Evguenia A. Karapetrova, Ahmet Uysal, Pulak DuttaAbstract:Oscillatory surface-density profiles (layers) have previously been reported in several metallic Liquids, one dielectric Liquid, and in computer simulations of dielectric Liquids. We have now seen surface layers in two other dielectric Liquids, pentaphenyl trimethyl trisiloxane, and pentavinyl pentamethyl cyclopentasiloxane. These layers appear below T?285 K and T?130 K, respectively; both thresholds correspond to T/ Tc ?0.2 where Tc is the Liquid-gas critical temperature. All metallic and dielectric Liquid Surfaces previously studied are also consistent with the existence of this T/ Tc threshold, first indicated by the simulations of Chac?n [Phys. Rev. Lett. 87, 166101 (2001)]. The layer width parameters, determined using a distorted-crystal fitting model, follow common trends as functions of Tc for both metallic and dielectric Liquids. ? 2010 The American Physical Society.
-
Order in molecular Liquids near solid–Liquid interfaces
Applied Surface Science, 2001Co-Authors: Chengjiao Yu, Guennadi Evmenenko, Andrew G. Richter, Alokmay Datta, J. Kmetko, Pulak DuttaAbstract:Abstract Much less is known about structure at solid–Liquid interfaces than at solid or Liquid Surfaces, largely because it is more difficult for experimental probes to penetrate into an interface. In recent years, the availability of synchrotron radiation (which is intense and collimated, and whose energy and thus penetration depth can be varied) has made scattering experiments at such interfaces possible. This article reviews some recent studies of ordering at the Liquid side of a solid–Liquid interface.
Peter Licence - One of the best experts on this subject based on the ideXlab platform.
-
charging of ionic Liquid Surfaces under x ray irradiation the measurement of absolute binding energies by xps
Physical Chemistry Chemical Physics, 2011Co-Authors: Ignacio J Villargarcia, Emily F. Smith, Alasdair W Taylor, Kevin R J Lovelock, Robert G Jones, Peter LicenceAbstract:Ionic Liquid Surfaces can become electrically charged during X-ray photoelectron spectroscopy experiments, due to the flux of photoelectrons leaving the surface. This causes a shift in the measured binding energies of X-ray photoelectron peaks that depends on the magnitude of the surface charging. Consequently, a charge correction method is required for ionic Liquids. Here we demonstrate the nature and extent of surface charging in ionic Liquids and model it using chronopotentiometry. We report the X-ray photoelectron spectra for a range of imidazolium based ionic Liquids and investigate the use of long alkyl chains (CnH2n+1, n ≥ 8) and the imidazolium nitrogen, both of which are part of the ionic Liquid chemical structure, as internal references for charge correction. Accurate and reproducible binding energies are obtained which allow comparisons to be made across ionic Liquid-based systems.
-
Ionic Liquids in vacuo: Analysis of Liquid Surfaces using ultra-high-vacuum techniques
Langmuir, 2006Co-Authors: Emily F. Smith, Ignacio J. Villar-garcia, David Briggs, Frank J. M. Rutten, Peter LicenceAbstract:Ultra-high-vacuum (UHV)-based techniques can offer the scientist a tremendous amount of information about samples of interest. However, until recently the range of samples that could be routinely investigated using unmodified instrumentation was limited to solid samples and frozen solutions. In this paper we report the investigation of low-vapor-pressure, Liquid samples using both X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. We demonstrate the suitability of UHV techniques in the investigation of a range of room-temperature ionic Liquids, offering the opportunity to measure high-quality solution-phase spectra using unmodified instrumentation.
Bogdan Gologan - One of the best experts on this subject based on the ideXlab platform.
-
ion soft landing into Liquids protein identification separation and purification with retention of biological activity
Journal of the American Society for Mass Spectrometry, 2004Co-Authors: Bogdan Gologan, Jormarie Alvarez, Zoltan Takats, Justin M Wiseman, Nari Talaty, Zheng Ouyang, Graham Robert CooksAbstract:Protein ions, after mass spectrometric separation, can be soft-landed into Liquid Surfaces with preservation of their native structures. Retention of biological activity is strongly favored in glycerol-based Surfaces but not in self-assembled monolayer solid Surfaces. Soft-landing efficiency for multiply-charged hexokinase ions was found to be some four times higher for a glycerol/fructose Liquid surface than for a fluorinated self-assembled monolayer surface. Soft-landing into Liquid Surfaces is also shown to allow (1) protein purification, (2) on-surface identification of the soft-landed material using MALDI, and (3) protein identification by in-surface tryptic digestion. Pure lysozyme was successfully isolated from different mixtures including an oxidized, partially decomposed batch of the protein and a partial tryptic digest. Liquid glycerol/carbohydrate mixtures could be used directly to record MALDI spectra on the soft-landed compounds provided they were fortified in advance with traditional MALDI matrices such as p-nitroaniline and α-cyano-4-hydroxycinnamic acid. Various proteins were soft-landed and detected on-target using these types of Liquid surface. Soft-landing of multiply-charged lysozyme ions onto fluorinated self-assembled monolayer Surfaces was found to occur with a limited amount of neutralization, and trapped multiply-charged ions could be desorbed from the surface by laser desorption. Initial data is shown for a new approach to protein identification that combines top-down and bottom-up approaches by utilizing protein ion soft-landing from a protein mixture, followed by tryptic digestion of the landed material and detection of characteristic tryptic fragments by MALDI.
-
preparing protein microarrays by soft landing of mass selected ions
Science, 2003Co-Authors: Zheng Ouyang, Bogdan Gologan, Zoltan Takats, Justin M Wiseman, Thomas A Blake, Andy J Guymon, Justin C Oliver, Jo V Davisson, Graham Robert CooksAbstract:Intact, multiply protonated proteins of particular mass and charge were selected from ionized protein mixtures and gently landed at different positions on a surface to form a microarray. An array of cytochrome c, lysozyme, insulin, and apomyoglobin was generated, and the deposited proteins showed electrospray ionization mass spectra that matched those of the authentic compounds. Deposited lysozyme and trypsin retained their biological activity. Multiply charged ions of protein kinase A catalytic subunit and hexokinase were also soft-landed into glycerol-based Liquid Surfaces. These soft-landed kinases phosphorylated LRRASLG oligopeptide and D-fructose, respectively.
Zheng Ouyang - One of the best experts on this subject based on the ideXlab platform.
-
ion soft landing into Liquids protein identification separation and purification with retention of biological activity
Journal of the American Society for Mass Spectrometry, 2004Co-Authors: Bogdan Gologan, Jormarie Alvarez, Zoltan Takats, Justin M Wiseman, Nari Talaty, Zheng Ouyang, Graham Robert CooksAbstract:Protein ions, after mass spectrometric separation, can be soft-landed into Liquid Surfaces with preservation of their native structures. Retention of biological activity is strongly favored in glycerol-based Surfaces but not in self-assembled monolayer solid Surfaces. Soft-landing efficiency for multiply-charged hexokinase ions was found to be some four times higher for a glycerol/fructose Liquid surface than for a fluorinated self-assembled monolayer surface. Soft-landing into Liquid Surfaces is also shown to allow (1) protein purification, (2) on-surface identification of the soft-landed material using MALDI, and (3) protein identification by in-surface tryptic digestion. Pure lysozyme was successfully isolated from different mixtures including an oxidized, partially decomposed batch of the protein and a partial tryptic digest. Liquid glycerol/carbohydrate mixtures could be used directly to record MALDI spectra on the soft-landed compounds provided they were fortified in advance with traditional MALDI matrices such as p-nitroaniline and α-cyano-4-hydroxycinnamic acid. Various proteins were soft-landed and detected on-target using these types of Liquid surface. Soft-landing of multiply-charged lysozyme ions onto fluorinated self-assembled monolayer Surfaces was found to occur with a limited amount of neutralization, and trapped multiply-charged ions could be desorbed from the surface by laser desorption. Initial data is shown for a new approach to protein identification that combines top-down and bottom-up approaches by utilizing protein ion soft-landing from a protein mixture, followed by tryptic digestion of the landed material and detection of characteristic tryptic fragments by MALDI.
-
preparing protein microarrays by soft landing of mass selected ions
Science, 2003Co-Authors: Zheng Ouyang, Bogdan Gologan, Zoltan Takats, Justin M Wiseman, Thomas A Blake, Andy J Guymon, Justin C Oliver, Jo V Davisson, Graham Robert CooksAbstract:Intact, multiply protonated proteins of particular mass and charge were selected from ionized protein mixtures and gently landed at different positions on a surface to form a microarray. An array of cytochrome c, lysozyme, insulin, and apomyoglobin was generated, and the deposited proteins showed electrospray ionization mass spectra that matched those of the authentic compounds. Deposited lysozyme and trypsin retained their biological activity. Multiply charged ions of protein kinase A catalytic subunit and hexokinase were also soft-landed into glycerol-based Liquid Surfaces. These soft-landed kinases phosphorylated LRRASLG oligopeptide and D-fructose, respectively.