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Characterization and Differential Cytotoxicity of Gramicidin Nanoparticles Combined with Cationic Polymer or Lipid Bilayer. Pharmaceutics 2022; 14:pharmaceutics14102053. [PMID: 36297488 PMCID: PMC9610547 DOI: 10.3390/pharmaceutics14102053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 09/20/2022] [Accepted: 09/23/2022] [Indexed: 11/21/2022] Open
Abstract
Gramicidin (Gr) nanoparticles (NPs) and poly (diallyl dimethyl ammonium) chloride (PDDA) water dispersions were characterized and evaluated against Gram-positive and Gram-negative bacteria and fungus. Dynamic light scattering for sizing, zeta potential analysis, polydispersity, and colloidal stability over time characterized Gr NPs/PDDA dispersions, and plating and colony-forming units counting determined their microbicidal activity. Cell viabilities of Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans in the presence of the combinations were reduced by 6, 7, and 7 logs, respectively, at 10 μM Gr/10 μg·mL−1 PDDA, 0.5 μM Gr/0. 5μg·mL−1 PDDA, and 0.5 μM Gr/0.5 μg·mL−1 PDDA, respectively. In comparison to individual Gr doses, the combinations reduced doses by half (S. aureus) and a quarter (C. albicans); in comparison to individual PDDA doses, the combinations reduced doses by 6 times (P. aeruginosa) and 10 times (C. albicans). Gr in supported or free cationic lipid bilayers reduced Gr activity against S. aureus due to reduced Gr access to the pathogen. Facile Gr NPs/PDDA disassembly favored access of each agent to the pathogen: PDDA suctioned the pathogen cell wall facilitating Gr insertion in the pathogen cell membrane. Gr NPs/PDDA differential cytotoxicity suggested the possibility of novel systemic uses for the combination.
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2
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Wang Y, Zhang Y, Qiao Z, Wang W. A 3D Printed Jet Mixer for Centrifugal Microfluidic Platforms. MICROMACHINES 2020; 11:mi11070695. [PMID: 32709009 PMCID: PMC7407664 DOI: 10.3390/mi11070695] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 07/14/2020] [Accepted: 07/14/2020] [Indexed: 01/09/2023]
Abstract
Homogeneous mixing of microscopic volume fluids at low Reynolds number is of great significance for a wide range of chemical, biological, and medical applications. An efficient jet mixer with arrays of micronozzles was designed and fabricated using additive manufacturing (three-dimensional (3D) printing) technology for applications in centrifugal microfluidic platforms. The contact surface of miscible liquids was enhanced significantly by impinging plumes from two opposite arrays of micronozzles to improve mixing performance. The mixing efficiency was evaluated and compared with the commonly used Y-shaped micromixer. Effective mixing in the jet mixer was achieved within a very short timescale (3s). This 3D printed jet mixer has great potential to be implemented in applications by being incorporated into multifarious 3D printing devices in microfluidic platforms.
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Kondrashov OV, Galimzyanov TR, Pavlov KV, Kotova EA, Antonenko YN, Akimov SA. Membrane Elastic Deformations Modulate Gramicidin A Transbilayer Dimerization and Lateral Clustering. Biophys J 2018; 115:478-493. [PMID: 30049405 PMCID: PMC6084527 DOI: 10.1016/j.bpj.2018.07.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 07/02/2018] [Accepted: 07/05/2018] [Indexed: 01/25/2023] Open
Abstract
Gramicidin A (gA) is a short β-helical peptide known to form conducting channels in lipid membranes because of transbilayer dimerization. The gA conducting dimer, being shorter than the lipid bilayer thickness, deforms the membrane in its vicinity, and the bilayer elastic energy contributes to the gA dimer formation energy. Likewise, membrane incorporation of a gA monomer, which is shorter than the lipid monolayer thickness, creates a void, thereby forcing surrounding lipid molecules to tilt to fill it. The energy of membrane deformation was calculated in the framework of the continuum elasticity theory, taking into account splay, tilt, lateral stretching/compression, Gaussian splay deformations, and external membrane tension. We obtained the interaction energy profiles for two gA monomers located either in the same or in the opposite monolayers. The profiles demonstrated the long-range attraction and short-range repulsion behavior of the monomers resulting from the membrane deformation. Analysis of the profile features revealed conditions under which clusters of gA monomers would not dissipate because of diffusion. The calculated dependence of the dimer formation and decay energy barriers on the membrane elastic properties was in good agreement with the available experimental data and suggested an explanation for a hitherto contentious phenomenon.
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Affiliation(s)
- Oleg V Kondrashov
- Laboratory of Bioelectrochemistry, A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia; Department of Theoretical Physics, Moscow Institute of Physics and Technology, Dolgoprudniy, Moscow Region, Russia
| | - Timur R Galimzyanov
- Laboratory of Bioelectrochemistry, A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia; Department of Theoretical Physics and Quantum Technologies, National University of Science and Technology "MISiS," Moscow, Russia
| | - Konstantin V Pavlov
- Laboratory of Electrophysiology, Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow, Russia
| | - Elena A Kotova
- Department of Photosynthesis and Fluorescence Research Methods, A. N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, Moscow, Russia
| | - Yuri N Antonenko
- Laboratory of Membrane Biophysics, A. N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, Moscow, Russia
| | - Sergey A Akimov
- Laboratory of Bioelectrochemistry, A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia; Department of Theoretical Physics and Quantum Technologies, National University of Science and Technology "MISiS," Moscow, Russia.
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Li J, Richards MR, Kitova EN, Klassen JS. Delivering Transmembrane Peptide Complexes to the Gas Phase Using Nanodiscs and Electrospray Ionization. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:2054-2065. [PMID: 28681358 DOI: 10.1007/s13361-017-1735-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 05/25/2017] [Accepted: 06/01/2017] [Indexed: 06/07/2023]
Abstract
The gas-phase conformations of dimers of the channel-forming membrane peptide gramicidin A (GA), produced from isobutanol or aqueous solutions of GA-containing nanodiscs (NDs), are investigated using electrospray ionization-ion mobility separation-mass spectrometry (ESI-IMS-MS) and molecular dynamics (MD) simulations. The IMS arrival times measured for (2GA + 2Na)2+ ions from isobutanol reveal three different conformations, with collision cross-sections (Ω) of 683 Å2 (conformation 1, C1), 708 Å2 (C2), and 737 Å2 (C3). The addition of NH4CH3CO2 produced (2GA + 2Na)2+ and (2GA + H + Na)2+ ions, with Ω similar to those of C1, C2, and C3, as well as (2GA + 2H)2+, (2GA + 2NH4)2+, and (2GA + H + NH4)2+ ions, which adopt a single conformation with a Ω similar to that of C2. These results suggest that the nature of the charging agents, imparted by the ESI process, can influence dimer conformation in the gas phase. Notably, the POPC NDs produced exclusively (2GA + 2NH4)2+ dimer ions; the DMPC NDs produced both (2GA + 2H)2+ and (2GA + 2NH4)2+ dimer ions. While the Ω of (2GA + 2H)2+ is similar to that of C2, the (2GA + 2NH4)2+ ions from NDs adopt a more compact structure, with a Ω of 656 Å2. It is proposed that this compact structure corresponds to the ion conducting single stranded head-to-head helical GA dimer. These findings highlight the potential of NDs, combined with ESI, for transferring transmembrane peptide complexes directly from lipid bilayers to the gas phase. Graphical Abstract ᅟ.
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Affiliation(s)
- Jun Li
- Alberta Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, T6G 2G2, Alberta, Canada
| | - Michele R Richards
- Alberta Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, T6G 2G2, Alberta, Canada
| | - Elena N Kitova
- Alberta Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, T6G 2G2, Alberta, Canada
| | - John S Klassen
- Alberta Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, T6G 2G2, Alberta, Canada.
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Patrick JW, Gamez RC, Russell DH. The Influence of Lipid Bilayer Physicochemical Properties on Gramicidin A Conformer Preferences. Biophys J 2017; 110:1826-1835. [PMID: 27119642 DOI: 10.1016/j.bpj.2016.03.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 02/11/2016] [Accepted: 03/07/2016] [Indexed: 11/19/2022] Open
Abstract
The conformational preferences adopted by gramicidin A (GA) dimers inserted into phospholipid bilayers are reported as a function of the bilayer cholesterol content, temperature, and incubation time. Through use of vesicle capture-freeze drying methodology, GA dimers were captured in lipid bilayers and the conformational preferences of the complex were analyzed using ion mobility-mass spectrometry. Perturbations that affect the physicochemical interactions in the lipid bilayer such as cholesterol incorporation, temperature, and incubation time directly alter the conformer preferences of the complex. Regardless of bilayer cholesterol concentration, the antiparallel double helix (ADH) conformation was observed to be most abundant for GA dimers in bilayers composed of lipids with 12 to 22 carbon acyl chains. Incorporation of cholesterol into lipid bilayers yields increased bilayer thickness and rigidity, and an increased abundance of parallel double helix (PDH) and single-stranded head-to-head (SSHH) dimers were observed. Bilayers prepared using 1,2-dilauroyl-sn-glycero-3-phosphocholine, a lipid with 12 carbon acyl chains, yielded a nascent conformer that decreased in abundance as a function of bilayer cholesterol content. High resolution ion mobility-mass spectrometry data revealed two peaks in the ADH region suggesting that ADH populations are composed of two distinct conformers. The conformer preferences of GA dimers from 1,2-distearoyl-sn-glycero-3-phosphocholine bilayers were significantly different for samples incubated at 4°C vs. 60°C; increased cholesterol content yielded more PDH and SSHH at 60°C. The addition of cholesterol as well as incubating samples of 1,2-distearoyl-sn-glycero-3-phosphocholine at 60°C for 24-72 h yielded an increase in PDH and SSHH abundance.
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Affiliation(s)
- John W Patrick
- Department of Chemistry, Texas A&M University, College Station, Texas
| | - Roberto C Gamez
- Department of Chemistry, Texas A&M University, College Station, Texas
| | - David H Russell
- Department of Chemistry, Texas A&M University, College Station, Texas.
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Patrick JW, Zerfas B, Gao J, Russell DH. Rapid capillary mixing experiments for the analysis of hydrophobic membrane complexes directly from aqueous lipid bilayer solutions. Analyst 2017; 142:310-315. [DOI: 10.1039/c6an02290a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mixing tee-electrospray ionization coupled to ion mobility-mass spectrometry reveals gramicidin A dimer conformer preferences.
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Affiliation(s)
- John W. Patrick
- Department of Chemistry
- Texas A&M University
- College Station
- USA
| | | | - Jianmin Gao
- Department of Chemistry
- Boston College
- Chestnut Hill
- USA
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Chen PS, Chen SH, Chen JH, Haung WY, Liu HT, Kong PH, Yang OHY. Modifier-assisted differential mobility–tandem mass spectrometry method for detection and quantification of amphetamine-type stimulants in urine. Anal Chim Acta 2016; 946:1-8. [DOI: 10.1016/j.aca.2016.09.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 09/23/2016] [Accepted: 09/24/2016] [Indexed: 10/20/2022]
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Garabedian A, Butcher D, Lippens JL, Miksovska J, Chapagain PP, Fabris D, Ridgeway ME, Park MA, Fernandez-Lima F. Structures of the kinetically trapped i-motif DNA intermediates. Phys Chem Chem Phys 2016; 18:26691-26702. [PMID: 27711445 PMCID: PMC5652045 DOI: 10.1039/c6cp04418b] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
In the present work, the conformational dynamics and folding pathways of i-motif DNA were studied in solution and in the gas-phase as a function of the solution pH conditions using circular dichroism (CD), photoacoustic calorimetry analysis (PAC), trapped ion mobility spectrometry-mass spectrometry (TIMS-MS), and molecular dynamics (MD). Solution studies showed at thermodynamic equilibrium the existence of a two-state folding mechanism, whereas during the pH = 7.0 → 4.5 transition a fast and slow phase (ΔHfast + ΔHslow = 43 ± 7 kcal mol-1) with a volume change associated with the formation of hemiprotonated cytosine base pairs and concomitant collapse of the i-motif oligonucleotide into a compact conformation were observed. TIMS-MS experiments showed that gas-phase, kinetically trapped i-motif DNA intermediates produced by nanoESI are preserved, with relative abundances depending on the solution pH conditions. In particular, a folded i-motif DNA structure was observed in nanoESI-TIMS-MS for low charge states in both positive and negative ion mode (e.g., z = ±3 to ±5) at low pH conditions. As solution pH increases, the cytosine neutralization leads to the loss of cytosine-cytosine+ (C·CH+) base pairing in the CCC strands and in those conditions we observe partially unfolded i-motif DNA conformations in nanoESI-TIMS-MS for higher charge states (e.g., z = -6 to -9). Collisional induced activation prior to TIMS-MS showed the existence of multiple local free energy minima, associated with the i-motif DNA unfolding at z = -6 charge state. For the first time, candidate gas-phase structures are proposed based on mobility measurements of the i-motif DNA unfolding pathway. Moreover, the inspection of partially unfolded i-motif DNA structures (z = -7 and z = -8 charge states) showed that the presence of inner cations may or may not induce conformational changes in the gas-phase. For example, incorporation of ammonium adducts does not lead to major conformational changes while sodium adducts may lead to the formation of sodium mediated bonds between two negatively charged sides inducing the stabilization towards more compact structures in new local, free energy minima in the gas-phase.
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Affiliation(s)
- Alyssa Garabedian
- Department of Chemistry and Biochemistry, Florida International University, Miami, USA.
| | - David Butcher
- Department of Chemistry and Biochemistry, Florida International University, Miami, USA.
| | | | - Jaroslava Miksovska
- Department of Chemistry and Biochemistry, Florida International University, Miami, USA. and Biomolecular Science Institute, Florida International University, Miami, USA
| | - Prem P Chapagain
- Biomolecular Science Institute, Florida International University, Miami, USA and Department of Physics, Florida International University, Miami, USA
| | | | | | - Melvin A Park
- Bruker Daltonics Inc., Billerica, Massachusetts, USA
| | - Francisco Fernandez-Lima
- Department of Chemistry and Biochemistry, Florida International University, Miami, USA. and Biomolecular Science Institute, Florida International University, Miami, USA
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9
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Silveira JA, Michelmann K, Ridgeway ME, Park MA. Fundamentals of Trapped Ion Mobility Spectrometry Part II: Fluid Dynamics. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:585-595. [PMID: 26864793 DOI: 10.1007/s13361-015-1310-z] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 11/02/2015] [Accepted: 11/06/2015] [Indexed: 06/05/2023]
Abstract
Trapped ion mobility spectrometry (TIMS) is a new high resolution (R up to ~300) separation technique that utilizes an electric field to hold ions stationary against a moving gas. Recently, an analytical model for TIMS was derived and, in part, experimentally verified. A central, but not yet fully explored, component of the model involves the fluid dynamics at work. The present study characterizes the fluid dynamics in TIMS using simulations and ion mobility experiments. Results indicate that subsonic laminar flow develops in the analyzer, with pressure-dependent gas velocities between ~120 and 170 m/s measured at the position of ion elution. One of the key philosophical questions addressed is: how can mobility be measured in a dynamic system wherein the gas is expanding and its velocity is changing? We noted previously that the analytically useful work is primarily done on ions as they traverse the electric field gradient plateau in the analyzer. In the present work, we show that the position-dependent change in gas velocity on the plateau is balanced by a change in pressure and temperature, ultimately resulting in near position-independent drag force. That the drag force, and related variables, are nearly constant allows for the use of relatively simple equations to describe TIMS behavior. Nonetheless, we derive a more comprehensive model, which accounts for the spatial dependence of the flow variables. Experimental resolving power trends were found to be in close agreement with the theoretical dependence of the drag force, thus validating another principal component of TIMS theory.
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Affiliation(s)
| | | | - Mark E Ridgeway
- Bruker Daltonics, 40 Manning Road, Billerica, MA, 01821, USA
| | - Melvin A Park
- Bruker Daltonics, 40 Manning Road, Billerica, MA, 01821, USA.
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Ridgeway ME, Wolff JJ, Silveira JA, Lin C, Costello CE, Park MA. Gated Trapped Ion Mobility Spectrometry Coupled to Fourier Transform Ion Cyclotron Resonance Mass Spectrometry. ACTA ACUST UNITED AC 2016; 19:77-85. [PMID: 27667964 DOI: 10.1007/s12127-016-0197-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Analysis of molecules by ion mobility spectrometry coupled with mass spectrometry (IMS-MS) provides chemical information on the three dimensional structure and mass of the molecules. The coupling of ion mobility to trapping mass spectrometers has historically been challenging due to the large differences in analysis time between the two devices. In this paper we present a modification of the trapped ion mobility (TIMS) analysis scheme termed "Gated TIMS" that allows efficient coupling to a Fourier Transform Ion Cyclotron Resonance (FT-ICR) analyzer. Analyses of standard compounds and the influence of source conditions on the TIMS distributions produced by ion mobility spectra of labile ubiquitin protein ions are presented. Ion mobility resolving powers up to 100 are observed. Measured collisional cross sections of ubiquitin ions are in excellent qualitative and quantitative agreement to previous measurements. Gated TIMS FT-ICR produces results comparable to those acquired using TIMS/time-of-flight MS instrument platforms as well as numerous drift tube IMS-MS studies published in the literature.
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Affiliation(s)
| | | | | | - Cheng Lin
- Mass Spectrometry Resource, Department of Biochemistry, Boston University School of Medicine, 670 Albany Street, Suite 504, Boston, MA 02118
| | - Catherine E Costello
- Mass Spectrometry Resource, Department of Biochemistry, Boston University School of Medicine, 670 Albany Street, Suite 504, Boston, MA 02118
| | - Melvin A Park
- Bruker Daltonics, 40 Manning Rd, Billerica, MA 01821
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Shi L, Holliday AE, Glover MS, Ewing MA, Russell DH, Clemmer DE. Ion Mobility-Mass Spectrometry Reveals the Energetics of Intermediates that Guide Polyproline Folding. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:22-30. [PMID: 26362047 PMCID: PMC4713193 DOI: 10.1007/s13361-015-1255-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 08/12/2015] [Accepted: 08/14/2015] [Indexed: 05/06/2023]
Abstract
Proline favors trans-configured peptide bonds in native proteins. Although cis/trans configurations vary for non-native and unstructured states, solvent also influences these preferences. Water induces the all-cis right-handed polyproline-I (PPI) helix of polyproline to fold into the all-trans left-handed polyproline-II (PPII) helix. Our recent work has shown that this occurs via a sequential mechanism involving six resolved intermediates [Shi, L., Holliday, A.E., Shi, H., Zhu, F., Ewing, M.A., Russell, D.H., Clemmer, D.E.: Characterizing intermediates along the transition from PPI to PPII using ion mobility-mass spectrometry. J. Am. Chem. Soc. 136, 12702-12711 (2014)]. Here, we use ion mobility-mass spectrometry to make the first detailed thermodynamic measurements of the folding intermediates, which inform us about how and why this transition occurs. It appears that early intermediates are energetically favorable because of the hydration of the peptide backbone, whereas late intermediates are enthalpically unfavorable. However, folding continues, as the entropy of the system increases upon successive formation of each new structure. When PPII is immersed in 1-propanol, the PPII→PPI transition occurs, but this reaction occurs through a very different mechanism. Early on, the PPII population splits onto multiple pathways that eventually converge through a late intermediate that continues on to the folded PPI helix. Nearly every step is endothermic. Folding results from a stepwise increase in the disorder of the system, allowing a wide-scale search for a critical late intermediate. Overall, the data presented here allow us to establish the first experimentally determined energy surface for biopolymer folding as a function of solution environment.
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Affiliation(s)
- Liuqing Shi
- Department of Chemistry, Indiana University, Bloomington, IN, 47405, USA
| | - Alison E Holliday
- Department of Chemistry, Moravian College, Bethlehem, PA, 18018, USA
| | - Matthew S Glover
- Department of Chemistry, Indiana University, Bloomington, IN, 47405, USA
| | - Michael A Ewing
- Department of Chemistry, Indiana University, Bloomington, IN, 47405, USA
| | - David H Russell
- Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - David E Clemmer
- Department of Chemistry, Indiana University, Bloomington, IN, 47405, USA.
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Marcoux J, Cianférani S. Towards integrative structural mass spectrometry: Benefits from hybrid approaches. Methods 2015; 89:4-12. [DOI: 10.1016/j.ymeth.2015.05.024] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 05/06/2015] [Accepted: 05/25/2015] [Indexed: 01/10/2023] Open
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Glover MS, Shi L, Fuller DR, Arnold RJ, Radivojac P, Clemmer DE. On the split personality of penultimate proline. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2015; 26:444-52. [PMID: 25503299 PMCID: PMC4336576 DOI: 10.1007/s13361-014-1049-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 11/03/2014] [Accepted: 11/10/2014] [Indexed: 05/12/2023]
Abstract
The influence of the position of the amino acid proline in polypeptide sequences is examined by a combination of ion mobility spectrometry-mass spectrometry (IMS-MS), amino acid substitutions, and molecular modeling. The results suggest that when proline exists as the second residue from the N-terminus (i.e., penultimate proline), two families of conformers are formed. We demonstrate the existence of these families by a study of a series of truncated and mutated peptides derived from the 11-residue peptide Ser(1)-Pro(2)-Glu(3)-Leu(4)-Pro(5)-Ser(6)-Pro(7)-Gln(8)-Ala(9)-Glu(10)-Lys(11). We find that every peptide from this sequence with a penultimate proline residue has multiple conformations. Substitution of Ala for Pro residues indicates that multiple conformers arise from the cis-trans isomerization of Xaa(1)-Pro(2) peptide bonds as Xaa-Ala peptide bonds are unlikely to adopt the cis isomer, and examination of spectra from a library of 58 peptides indicates that ~80% of sequences show this effect. A simple mechanism suggesting that the barrier between the cis- and trans-proline forms is lowered because of low steric impedance is proposed. This observation may have interesting biological implications as well, and we note that a number of biologically active peptides have penultimate proline residues.
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Affiliation(s)
- Matthew S. Glover
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Liuqing Shi
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Daniel R. Fuller
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Randy J. Arnold
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Predrag Radivojac
- Department of Computer Science and Informatics, Indiana University, Bloomington, IN 47405, USA
| | - David E. Clemmer
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
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Ridgeway ME, Silveira JA, Meier JE, Park MA. Microheterogeneity within conformational states of ubiquitin revealed by high resolution trapped ion mobility spectrometry. Analyst 2015; 140:6964-72. [DOI: 10.1039/c5an00841g] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The present work employs trapped ion mobility spectrometry (TIMS) for the analysis of ubiquitin ions known to display a multitude of previously unresolved interchangeable conformations upon electrospray ionization.
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15
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Michelmann K, Silveira JA, Ridgeway ME, Park MA. Fundamentals of trapped ion mobility spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2015; 26:14-24. [PMID: 25331153 DOI: 10.1007/s13361-014-0999-4] [Citation(s) in RCA: 241] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 09/04/2014] [Accepted: 09/04/2014] [Indexed: 05/18/2023]
Abstract
Trapped ion mobility spectrometry (TIMS) is a relatively new gas-phase separation method that has been coupled to quadrupole orthogonal acceleration time-of-flight mass spectrometry. The TIMS analyzer is a segmented rf ion guide wherein ions are mobility-analyzed using an electric field that holds ions stationary against a moving gas, unlike conventional drift tube ion mobility spectrometry where the gas is stationary. Ions are initially trapped, and subsequently eluted from the TIMS analyzer over time according to their mobility (K). Though TIMS has achieved a high level of performance (R > 250) in a small device (<5 cm) using modest operating potentials (<300 V), a proper theory has yet to be produced. Here, we develop a quantitative theory for TIMS via mathematical derivation and simulations. A one-dimensional analytical model, used to predict the transit time and theoretical resolving power, is described. Theoretical trends are in agreement with experimental measurements performed as a function of K, pressure, and the axial electric field scan rate. The linear dependence of the transit time with 1/K provides a fundamental basis for determination of reduced mobility or collision cross section values by calibration. The quantitative description of TIMS provides an operational understanding of the analyzer, outlines the current performance capabilities, and provides insight into future avenues for improvement.
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Patrick JW, Gamez RC, Russell DH. Elucidation of Conformer Preferences for a Hydrophobic Antimicrobial Peptide by Vesicle Capture-Freeze-Drying: A Preparatory Method Coupled to Ion Mobility-Mass Spectrometry. Anal Chem 2014; 87:578-83. [DOI: 10.1021/ac503163g] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- John W. Patrick
- The Laboratory for Biological Mass Spectrometry, Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Roberto C. Gamez
- The Laboratory for Biological Mass Spectrometry, Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - David H. Russell
- The Laboratory for Biological Mass Spectrometry, Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
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Molano-Arevalo JC, Hernandez DR, Gonzalez WG, Miksovska J, Ridgeway ME, Park MA, Fernandez-Lima F. Flavin adenine dinucleotide structural motifs: from solution to gas phase. Anal Chem 2014; 86:10223-30. [PMID: 25222439 PMCID: PMC4204916 DOI: 10.1021/ac5023666] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
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Flavin
adenine dinucleotide (FAD) is involved in important metabolic
reactions where the biological function is intrinsically related to
changes in conformation. In the present work, FAD conformational changes
were studied in solution and in gas phase by measuring the fluorescence
decay time and ion-neutral collision cross sections (CCS, in a trapped
ion mobility spectrometer, TIMS) as a function of the solvent conditions
(i.e., organic content) and gas-phase collisional partner (i.e., N2 doped with organic molecules). Changes in the fluorescence
decay suggest that FAD can exist in four conformations in solution,
where the abundance of the extended conformations increases with the
organic content. TIMS-MS experiments showed that FAD can exist in
the gas phase as deprotonated (M = C27H31N9O15P2) and protonated forms (M = C27H33N9O15P2) and
that multiple conformations (up to 12) can be observed as a function
of the starting solution for the [M + H]+ and [M + Na]+molecular ions. In addition, changes in the relative abundances
of the gas-phase structures were observed from a “stack”
to a “close” conformation when organic molecules were
introduced in the TIMS cell as collision partners. Candidate structures
optimized at the DFT/B3LYP/6-31G(d,p) were proposed for each IMS band,
and results showed that the most abundant IMS band corresponds to
the most stable candidate structure. Solution and gas-phase experiments
suggest that the driving force that stabilizes the different conformations
is based on the interaction of the adenine and isoalloxazine rings
that can be tailored by the “solvation” effect created
with the organic molecules.
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Affiliation(s)
- Juan Camilo Molano-Arevalo
- Department of Chemistry and Biochemistry, Florida International University , Miami, Florida 33199, United States
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Hyung SJ, Feng X, Che Y, Stroh JG, Shapiro M. Detection of conformation types of cyclosporin retaining intramolecular hydrogen bonds by mass spectrometry. Anal Bioanal Chem 2014; 406:5785-94. [DOI: 10.1007/s00216-014-8023-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 07/02/2014] [Accepted: 07/07/2014] [Indexed: 11/24/2022]
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Chen SH, Chen L, Russell DH. Metal-induced conformational changes of human metallothionein-2A: a combined theoretical and experimental study of metal-free and partially metalated intermediates. J Am Chem Soc 2014; 136:9499-508. [PMID: 24918957 DOI: 10.1021/ja5047878] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Electrospray ionization ion mobility mass spectrometry (ESI IM-MS) and molecular dynamics (MD) simulations reveal new insights into metal-induced conformational changes and the mechanism for metalation of human metallothionein-2A (MT), an intrinsically disordered protein. ESI of solutions containing apoMT yields multiple charge states of apoMT; following addition of Cd(2+) to the solution, ESI yields a range of CdiMT (i = 1-7) product ions (see Chen et al. Anal. Chem. 2013, 85, 7826-33). Ion mobility arrival-time distributions (ATDs) for the CdiMT (i = 0-7) ions reveal a diverse population of ion conformations. The ion mobility data clearly show that the conformational diversity for apoMT and partially metalated ions converges toward ordered, compact conformations as the number of bound Cd(2+) ions increase. MD simulations provide additional information on conformation candidates of CdiMT (i = 0-7) that supports the convergence of distinct conformational populations upon metal binding. Integrating the IM-MS and MD data provides a global view that shows stepwise conformational transition of an ensemble as a function of metal ion bound. ApoMT is comprised of a wide range of conformational states that populate between globular-like compact and coil-rich extended conformations. During the initial stepwise metal addition (number of metal ions bound i = 1-3), the metal ions bind to different sites to yield distinct conformations, whereas for i > 4, the conformational changes appear to be domain-specific, attributed to different degrees of disorder of the β domain; the β domain becomes more ordered as additional metal ions are added, promoting convergences to the dumbbell-shaped conformation.
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Affiliation(s)
- Shu-Hua Chen
- Department of Chemistry, Texas A&M University , College Station, Texas 77843, United States
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Silveira JA, Ridgeway ME, Park MA. High Resolution Trapped Ion Mobility Spectrometery of Peptides. Anal Chem 2014; 86:5624-7. [DOI: 10.1021/ac501261h] [Citation(s) in RCA: 135] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Joshua A. Silveira
- Bruker Daltonics, 40 Manning
Road, Billerica, Massachusetts 01821, United States
| | - Mark E. Ridgeway
- Bruker Daltonics, 40 Manning
Road, Billerica, Massachusetts 01821, United States
| | - Melvin A. Park
- Bruker Daltonics, 40 Manning
Road, Billerica, Massachusetts 01821, United States
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