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Yang P, Guo W, Ramamoorthy A, Chen Z. Conformation and Orientation of Antimicrobial Peptides MSI-594 and MSI-594A in a Lipid Membrane. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:5352-5363. [PMID: 37017985 DOI: 10.1021/acs.langmuir.2c03430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
There is significant interest in the development of antimicrobial compounds to overcome the increasing bacterial resistance to conventional antibiotics. Studies have shown that naturally occurring and de novo-designed antimicrobial peptides could be promising candidates. MSI-594 is a synthetic linear, cationic peptide that has been reported to exhibit a broad spectrum of antimicrobial activities. Investigation into how MSI-594 disrupts the cell membrane is important for better understanding the details of this antimicrobial peptide (AMP)'s action against bacterial cells. In this study, we used two different synthetic lipid bilayers: zwitterionic 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and anionic 7:3 POPC/1-palmitoyl-2-oleoyl-sn-glycero-3-phospho(1'-rac-glycerol) (POPG). Sum frequency generation (SFG) vibrational spectroscopy and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) were used to determine the orientations of MSI-594 and its analogue MSI-594A associated with zwitterionic POPC and anionic 7:3 POPC/POPG lipid bilayers. The simulated ATR-FTIR and SFG spectra using nuclear magnetic resonance (NMR)-determined structures were compared with experimental spectra to optimize the bent angle between the N- (1-11) and C- (12-24) termini helices and the membrane orientations of the helices; since the NMR structure of the peptide was determined from lipopolysaccharide (LPS) micelles, the optimization was needed to find the most suitable conformation and orientation in lipid bilayers. The reported experimental results indicate that the optimized MSI-594 helical hairpin structure adopts a complete lipid bilayer surface-bound orientation (denoted "face-on") in both POPC and 7:3 POPC/POPG lipid bilayers. The analogue peptide, MSI-584A, on the other hand, exhibited a larger bent angle between the N- (1-11) and C- (12-24) termini helices with the hydrophobic C-terminal helix inserted into the hydrophobic region of the bilayer (denoted "membrane-inserted") when interacting with both POPC and 7:3 POPC/POPG lipid bilayers. These experimental findings on the membrane orientations suggest that both peptides are likely to disrupt the cell membrane through the carpet mechanism.
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Affiliation(s)
- Pei Yang
- Department of Chemistry, The University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Wen Guo
- Department of Chemistry, The University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Ayyalusamy Ramamoorthy
- Department of Chemistry, The University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055, United States
- Department of Biophysics, The University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Zhan Chen
- Department of Chemistry, The University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055, United States
- Department of Biophysics, The University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055, United States
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Machmud A, Chang MB. Modifying α-Al 2O 3 with cerium, zirconium, and sulfate for catalytic removal of C 4F 8. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:25920-25932. [PMID: 36352070 DOI: 10.1007/s11356-022-23953-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 10/28/2022] [Indexed: 06/16/2023]
Abstract
Modification of α-Al2O3 (A) with cerium (C), zirconium (Z), and sulfate (S) for effective C4F8 removal is evaluated at temperatures ≤ 650 °C. Catalytic hydrolysis of C4F8 is conducted to compare the performance of catalysts prepared (namely, A, AC, AZ, AS, ACS, and AZS). The interplay between rare earth element, acid amount, and surface area is further investigated. An investigation was carried out by characterization of catalysts by using XRD, BET, and NH3-TPD. XRD pattern of the modified α-Al2O3 catalyst shows that the average grain size is 37 nm. BET analysis indicates that the surface area increases with the addition of Ce and Zr, while NH3-TPD analysis shows the improvement of acid sites after the addition of Ce, Zr, and SO42-. The experimental results indicate that C4F8 conversion over A catalyst reaches 14.81% at 550 °C with the addition of 38% H2O(g). Under the same operating condition, C4F8 conversion efficiencies achieved with AC and AZ catalysts increase to 42.03% and 50.1%, respectively. Furthermore, the efficiencies over AS, ACS, and AZS catalysts increase to 49.85%, 86.94%, and 87.18%, respectively. Stability tests show that the performances of the catalysts for C4F8 conversion are with the order of AZS > ACS > AZ > AC > AS > A at 650 °C during 24 h. The activation energy of the AZS catalyst in catalytic hydrolysis of C4F8 is 60.49 kJ/mol. The products of C4F8 conversion mainly include CO2, CO, and COF2 and small amounts of CHF3 and C2F4. This study has confirmed that the AZS catalyst shows the best activity, acidity, and stability on C4F8 removal.
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Affiliation(s)
- Amir Machmud
- Graduate Institute of Environmental Engineering, National Central University, No.300, Zhongda Road, Zhongli District, Taoyuan City, 32001, Taiwan
| | - Moo Been Chang
- Graduate Institute of Environmental Engineering, National Central University, No.300, Zhongda Road, Zhongli District, Taoyuan City, 32001, Taiwan.
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Boily JF, Fu L, Tuladhar A, Lu Z, Legg BA, Wang ZM, Wang H. Hydrogen bonding and molecular orientations across thin water films on sapphire. J Colloid Interface Sci 2019; 555:810-817. [PMID: 31425917 DOI: 10.1016/j.jcis.2019.08.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 08/07/2019] [Accepted: 08/08/2019] [Indexed: 01/28/2023]
Abstract
HYPOTHESIS Water vapor binding to metal oxide surfaces produces thin water films with properties controlled by interactions with surface hydroxo sites. Hydrogen bonding populations vary across films and induce different molecular orientations than at the surface of liquid water. Identifying these differences can open possibilities for tailoring film-mediated catalytic reactions by choice of the supporting metal oxide substrate. EXPERIMENTS The (0001) face of a single sapphire (α-Al2O3) sample exposed to water vapor and the surface of liquid water were probed by polarization dependent Sum Frequency Generation-Vibration Spectroscopy (SFG-VS). Molecular dynamics (MD) provided insight into the hydrogen bond populations and molecular orientations across films and liquid water. FINDINGS SFG-VS revealed a submonolayer film on sapphire exposed to 43% relative humidity (R.H.), and a multilayer film at 78% R.H. Polarization dependent SFG-VS spectra showed that median tilt angles of free OH bonds on the top of films are at ∼43° from the normal of the (0001) face but at 38° on neat liquid water. These values align with MD simulations, which also show that up to 36% of all OH bonds on films are free. This offers new means for understanding how interfacial reactions on sapphire-supported water films could contrast with those involving liquid water.
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Affiliation(s)
| | - Li Fu
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Aashish Tuladhar
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Zhou Lu
- Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Benjamin A Legg
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Zheming M Wang
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Hongfei Wang
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200438, China
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Fang Y, Tang M, Grassian VH. Competition between Displacement and Dissociation of a Strong Acid Compared to a Weak Acid Adsorbed on Silica Particle Surfaces: The Role of Adsorbed Water. J Phys Chem A 2016; 120:4016-24. [DOI: 10.1021/acs.jpca.6b02262] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yuan Fang
- Department
of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
- Department
of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, United States
| | - Mingjin Tang
- Department
of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Vicki H. Grassian
- Department
of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
- Department
of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, United States
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Yang P, Homan KT, Li Y, Cruz-Rodríguez O, Tesmer JJG, Chen Z. Effect of Lipid Composition on the Membrane Orientation of the G Protein-Coupled Receptor Kinase 2-Gβ1γ2 Complex. Biochemistry 2016; 55:2841-8. [PMID: 27088923 DOI: 10.1021/acs.biochem.6b00354] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Interactions between proteins and cell membranes are critical for biological processes such as transmembrane signaling, and specific components of the membrane may play roles in helping to organize or mandate particular conformations of both integral and peripheral membrane proteins. One example of a signaling enzyme whose function is dependent on membrane binding and whose activity is affected by specific lipid components is G protein-coupled receptor (GPCR) kinase 2 (GRK2). Efficient GRK2-mediated phosphorylation of activated GPCRs is dependent not only on its recruitment to the membrane by heterotrimeric Gβγ subunits but also on the presence of highly negatively charged lipids, in particular phosphatidylinositol 4',5'-bisphosphate (PIP2). We hypothesized that PIP2 may favor a distinct orientation of the GRK2-Gβγ complex on the membrane that is more optimal for function. In this study, we compared the possible orientations of the GRK2-Gβγ complex and Gβγ alone on model cell membranes prepared with various anionic phospholipids as deduced from sum frequency generation vibrational and attenuated total reflectance Fourier transform infrared spectroscopic methods. Our results indicate that PIP2 affects the membrane orientation of the GRK2-Gβ1γ2 complex but not that of complexes formed with anionic phospholipid binding deficient mutations in the GRK2 pleckstrin homology (PH) domain. Gβ1γ2 exhibits a similar orientation on the lipid bilayer regardless of its lipid composition. The PIP2-induced orientation of the GRK2-Gβ1γ2 complex is therefore most likely caused by specific interactions between PIP2 and the GRK2 PH domain. Thus, PIP2 not only helps recruit GRK2 to the membrane but also "fine tunes" the orientation of the GRK2-Gβγ complex so that it is better positioned to phosphorylate activated GPCRs.
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Affiliation(s)
- Pei Yang
- Department of Chemistry, University of Michigan , 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Kristoff T Homan
- Departments of Pharmacology and Biological Chemistry, Life Sciences Institute, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Yaoxin Li
- Department of Chemistry, University of Michigan , 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Osvaldo Cruz-Rodríguez
- Departments of Pharmacology and Biological Chemistry, Life Sciences Institute, University of Michigan , Ann Arbor, Michigan 48109, United States.,Ph.D. Program in Chemical Biology, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - John J G Tesmer
- Departments of Pharmacology and Biological Chemistry, Life Sciences Institute, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Zhan Chen
- Department of Chemistry, University of Michigan , 930 North University Avenue, Ann Arbor, Michigan 48109, United States
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Tang M, Cziczo DJ, Grassian VH. Interactions of Water with Mineral Dust Aerosol: Water Adsorption, Hygroscopicity, Cloud Condensation, and Ice Nucleation. Chem Rev 2016; 116:4205-59. [DOI: 10.1021/acs.chemrev.5b00529] [Citation(s) in RCA: 228] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Mingjin Tang
- Department
of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Daniel J. Cziczo
- Department
of Earth, Atmospheric and Planetary Sciences and Civil and Environmental
Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Vicki H. Grassian
- Department
of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
- Departments
of Chemistry and Biochemistry, Nanoengineering and Scripps Institution
of Oceanography, University of California San Diego, La Jolla, California 92093, United States
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Ebrahimpour O, Esmaeili B, Griffon L, Chaouki J, Dubois C. Novel fabrication route for porous silicon carbide ceramics through the combination ofin situpolymerization and reaction bonding techniques. J Appl Polym Sci 2014. [DOI: 10.1002/app.40425] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Omid Ebrahimpour
- Department of Chemical Engineering; École Polytechnique de Montréal; P.O. Box 6079, Station Centre-Ville Montréal Canada
| | - Babak Esmaeili
- Department of Chemical Engineering; École Polytechnique de Montréal; P.O. Box 6079, Station Centre-Ville Montréal Canada
| | - Lucie Griffon
- Department of Chemical Engineering; École Polytechnique de Montréal; P.O. Box 6079, Station Centre-Ville Montréal Canada
| | - Jamal Chaouki
- Department of Chemical Engineering; École Polytechnique de Montréal; P.O. Box 6079, Station Centre-Ville Montréal Canada
| | - Charles Dubois
- Department of Chemical Engineering; École Polytechnique de Montréal; P.O. Box 6079, Station Centre-Ville Montréal Canada
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Yang P, Glukhova A, Tesmer JJG, Chen Z. Membrane orientation and binding determinants of G protein-coupled receptor kinase 5 as assessed by combined vibrational spectroscopic studies. PLoS One 2013; 8:e82072. [PMID: 24278472 PMCID: PMC3838385 DOI: 10.1371/journal.pone.0082072] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2013] [Accepted: 10/20/2013] [Indexed: 11/18/2022] Open
Abstract
G-protein coupled receptors (GPCRs) are integral membrane proteins involved in a wide variety of biological processes in eukaryotic cells, and are targeted by a large fraction of marketed drugs. GPCR kinases (GRKs) play important roles in feedback regulation of GPCRs, such as of β-adrenergic receptors in the heart, where GRK2 and GRK5 are the major isoforms expressed. Membrane targeting is essential for GRK function in cells. Whereas GRK2 is recruited to the membrane by heterotrimeric Gβγ subunits, the mechanism of membrane binding by GRK5 is not fully understood. It has been proposed that GRK5 is constitutively associated with membranes through elements located at its N-terminus, its C-terminus, or both. The membrane orientation of GRK5 is also a matter of speculation. In this work, we combined sum frequency generation (SFG) vibrational spectroscopy and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) to help determine the membrane orientation of GRK5 and a C-terminally truncated mutant (GRK51-531) on membrane lipid bilayers. It was found that GRK5 and GRK51-531 adopt a similar orientation on model cell membranes in the presence of PIP2 that is similar to that predicted for GRK2 in prior studies. Mutation of the N-terminal membrane binding site of GRK5 did not eliminate membrane binding, but prevented observation of this discrete orientation. The C-terminus of GRK5 does not have substantial impact on either membrane binding or orientation in this model system. Thus, the C-terminus of GRK5 may drive membrane binding in cells via interactions with other proteins at the plasma membrane or bind in an unstructured manner to negatively charged membranes.
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Affiliation(s)
- Pei Yang
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Alisa Glukhova
- Departments of Pharmacology and Biological Chemistry, Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, United States of America
- Program in Chemical Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - John J. G. Tesmer
- Departments of Pharmacology and Biological Chemistry, Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail: (ZC); (JJGT)
| | - Zhan Chen
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail: (ZC); (JJGT)
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Yang P, Wu FG, Chen Z. Lipid Fluid-Gel Phase Transition Induced Alamethicin Orientational Change Probed by Sum Frequency Generation Vibrational Spectroscopy. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2013; 117:17039-17049. [PMID: 24124624 PMCID: PMC3792402 DOI: 10.1021/jp4047215] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Alamethicin has been extensively studied as an antimicrobial peptide (AMP) and is widely used as a simple model for ion channel proteins. It has been shown that the antimicrobial activity of AMPs is related to their cell membrane orientation, which may be influenced by the phase of the lipid molecules in the cell membrane. The "healthy" cell membranes contain fluid phase lipids, while gel phase lipids can be found in injured or aged cells or in some phase separated membrane regions. Thus, investigations on how the phase of the lipids influences the membrane orientation of AMPs are important to understand more details regarding the AMP's action on cell membranes. In this study, we determined the orientational changes of alamethicin molecules associated with planar substrate supported single lipid bilayers (serving as model cell membranes) with different phases (fluid or gel) as a function of peptide concentration using sum frequency generation (SFG) vibrational spectroscopy. The phase changes of the lipid bilayers were realized by varying the sample temperature. Our SFG results indicated that alamethicin lies down on the surface of fluid and gel phase 1,2-dimyristoyl(d54)-sn-glycero-3-phosphocholine (d-DMPC) lipid bilayers when the lipid bilayers are in contact with a peptide solution with a low concentration of 0.84 μM. However, at a medium peptide concentration of 10.80 μM, alamethicin inserts into the fluid phase lipid bilayer. Its orientation switches from a transmembrane to an in-plane (or lying down) orientation when the phase of the lipid bilayer changes from a fluid state to a gel state. At a high peptide concentration of 21.60 μM, alamethicin adopts a transmembrane orientation while associated with both fluid and gel phase lipid bilayers. We also studied the structural changes of the fluid and gel phase lipid bilayers upon their interactions with alamethicin molecules at different peptide concentrations.
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Affiliation(s)
| | | | - Zhan Chen
- To whom correspondence should be addressed. Fax: 734-647-4865;
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Yang P, Boughton A, Homan KT, Tesmer JJG, Chen Z. Membrane orientation of Gα(i)β(1)γ(2) and Gβ(1)γ(2) determined via combined vibrational spectroscopic studies. J Am Chem Soc 2013; 135:5044-51. [PMID: 23461393 DOI: 10.1021/ja3116026] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The manner in which the heterotrimeric G protein complexes Gβ1γ2 and Gαiβ1γ2 interact with membranes is likely related to their biological function. We combined complementary measurements from sum frequency generation (SFG) vibrational and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy to determine the possible membrane orientations of Gβ1γ2 and the Gαiβ1γ2 heterotrimer more precisely than could be achieved using SFG alone. The most likely orientations of Gβ1γ2 and the Gαiβ1γ2 heterotrimer were both determined to fall within a similar narrow range of twist and tilt angles, suggesting that Gβ1γ2 may bind to Gαi without a significant change in orientation. This "basal" orientation seems to depend primarily on the geranylgeranylated C-terminus of Gγ2 along with basic residues at the N-terminus of Gαi, and suggests that activated G protein-coupled receptors (GPCRs) must reorient G protein heterotrimers at lipid bilayers to catalyze nucleotide exchange. The innovative methodologies developed in this paper can be widely applied to study the membrane orientation of other proteins in situ.
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Affiliation(s)
- Pei Yang
- Department of Chemistry, University of Michiga n, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
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Yang P, Wu FG, Chen Z. Dependence of Alamethicin Membrane Orientation on the Solution Concentration. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2013; 117:3358-3365. [PMID: 23565299 PMCID: PMC3613978 DOI: 10.1021/jp3099522] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Alamethicin has been extensively studied as an antimicrobial peptide and is widely used as a simple model for ion channel proteins. It has been shown that the antimicrobial activity of peptides is related to their membrane orientation. In this study, we determined the relationship between the solution concentration of alamethicin and its membrane orientation in lipid bilayers using sum frequency generation (SFG) vibrational spectroscopy. Our SFG results indicated that the alamethicin molecules more or less lay down on the surface of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) lipid bilayers at a low peptide concentration of 0.84 μM; the α-helix segment tilts at about 88°, and 310-helix segment tilts at about 58° versus the surface normal. However, when the peptide concentration was increased to 15.6 μM, we observed that alamethicin molecules further inserted into the lipid bilayers: the α-helical component changes its orientation to make a 37° tilt from the lipid bilayer normal, and the 310-helical component tilts at about 50° versus the surface normal. This is in agreement with the barrel-stave mode for the alamethicin-cell membrane interaction as reported previously. Additionally, we have also studied membrane orientation of alamethicin as a function of peptide concentration with SFG. Our results showed that the membrane orientation of the alamethicin α-helical component changed substantially with the increase of the alamethicin concentration, while the membrane orientation of the 310-helical component remained more or less the same.
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Affiliation(s)
| | | | - Zhan Chen
- To whom correspondence should be addressed. Fax: 734-647-4865.
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13
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Yang P, Ramamoorthy A, Chen Z. Membrane orientation of MSI-78 measured by sum frequency generation vibrational spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:7760-7. [PMID: 21595453 PMCID: PMC3119716 DOI: 10.1021/la201048t] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Antimicrobial peptides (AMPs) selectively disrupt bacterial cell membranes to kill bacteria whereas they either do not or weakly interact with mammalian cells. The orientations of AMPs in lipid bilayers mimicking bacterial and mammalian cell membranes are related to their antimicrobial activity and selectivity. To understand the role of AMP-lipid interactions in the functional properties of AMPs better, we determined the membrane orientation of an AMP (MSI-78 or pexiganan) in various model membranes using sum frequency generation (SFG) vibrational spectroscopy. A solid-supported single 1,2-dipalmitoyl-an-glycero-3-[phospho-rac-(1-glycerol)] (DPPG) bilayer or 1-palmitoyl-2-oleoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (POPG) bilayer was used as a model bacterial cell membrane. A supported 1,2-dipalmitoyl-an-glycero-3-phosphocholine (DPPC) bilayer or a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayer was used as a model mammalian cell membrane. Our SFG results indicate that the helical MSI-78 molecules are associated with the bilayer surface with ∼70° deviation from the bilayer normal in the negatively charged gel-phase DPPG bilayer at 400 nM peptide concentration. However, when the concentration was increased to 600 nM, MSI-78 molecules changed their orientation to make a 25° tilt from the lipid bilayer normal whereas multiple orientations were observed for an even higher peptide concentration in agreement with toroidal-type pore formation as reported in a previous solid-state NMR study. In contrary, no interaction between MSI-78 and a zwitterionic DPPC bilayer was observed even at a much higher peptide concentration (∼12,000 nM). These results demonstrate that SFG can provide insights into the antibacterial activity and selectivity of MSI-78. Interestingly, the peptide exhibits a concentration-dependent membrane orientation in the lamellar-phase POPG bilayer and was also found to induce toroidal-type pore formation. The deduced lipid flip-flop from SFG signals observed from lipids also supports MSI-78-induced toroidal-type pore formation.
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Affiliation(s)
- Pei Yang
- Biophysics and Department of Chemistry, 930 North University Avenue, University of Michigan, Ann Arbor, Michigan 48109
| | - Ayyalusamy Ramamoorthy
- Biophysics and Department of Chemistry, 930 North University Avenue, University of Michigan, Ann Arbor, Michigan 48109
| | - Zhan Chen
- Biophysics and Department of Chemistry, 930 North University Avenue, University of Michigan, Ann Arbor, Michigan 48109
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Wang T, Li D, Lu X, Khmaladze A, Han X, Ye S, Yang P, Xue G, He N, Chen Z. Single Lipid Bilayers Constructed on Polymer Cushion Studied by Sum Frequency Generation Vibrational Spectroscopy. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2011; 115:7613-7620. [PMID: 21712964 PMCID: PMC3122884 DOI: 10.1021/jp200546h] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Planar solid supported single lipid bilayers on mica, glass, or other inorganic surfaces have been widely used as models for cell membranes. To more closely mimic the cell membrane environment, soft hydrophilic polymer cushions were introduced between the hard inorganic substrate and the lipid bilayer to completely avoid the possible substrate-lipid interactions. In this article, sum frequency generation (SFG) vibrational spectroscopy was used to examine and compare single lipid bilayers assembled on the CaF(2) prism surface and on poly (L-lactic acid) (PLLA) cushion. By using asymmetric lipid bilayers composed of a hydrogenated 1,2-dipalmitoyl-sn-glycerol-3-phosphoglycerol (DPPG) leaflet and a deuterated 1,2-dipalmitoyl-(d62)-sn-glycerol-3-phosphoglycerol (d-DPPG) leaflet, it was shown that the DPPG lipid bilayers deposited on the CaF(2) and PLLA surfaces have similar structures. SFG has also been applied to investigate molecular interactions between an antimicrobial peptide Cecropin P(1) (CP1) and the lipid bilayers on the above two different surfaces. Similar results were again obtained. This research demonstrated that the hydrophilic PLLA cushion can serve as an excellent substrate to support single lipid bilayers. We believe that it can be an important cell membrane model for future studies on transmembrane proteins, for which the possible inorganic substrate-bilayer interactions may affect the protein structure or function.
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Affiliation(s)
- Ting Wang
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing, 210096, China
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Dawei Li
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
- State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructure, Department of Polymer Science and Engineering, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210093, China
| | - Xiaolin Lu
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | | | - Xiaofeng Han
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Shuji Ye
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Pei Yang
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Gi Xue
- State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructure, Department of Polymer Science and Engineering, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210093, China
| | - Nongyue He
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing, 210096, China
| | - Zhan Chen
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
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15
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Avery CW, Palermo EF, McLaughlin A, Kuroda K, Chen Z. Investigations of the interactions between synthetic antimicrobial polymers and substrate-supported lipid bilayers using sum frequency generation vibrational spectroscopy. Anal Chem 2011; 83:1342-9. [PMID: 21229969 DOI: 10.1021/ac1025804] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Sum frequency generation (SFG) vibrational spectroscopy was used to analyze interactions between solid-supported lipid bilayers acting as models for cellular membranes and several membrane-active random copolymers with different lipophilic side chains, named 0R (no group), 33Me (methyl group), 11Bz (benzyl group), and 33Bu (butyl group), according to both the identity and percentage of the side chains within the polymer. Biological tests of the minimum inhibitory concentration (MIC) and hemolytic concentration were performed. The inherent surface sensitivity of SFG allowed for independent monitoring of isotopically labeled lipid bilayer leaflets as a function of concentration to study polymer-bilayer interaction mechanisms. Concentrations at which each bilayer leaflet was disrupted were quantitatively determined for each copolymer. Spectroscopic evidence of interaction with the bilayer below the critical concentrations was observed for the 11Bz polymer. The lipophilic butyl side chain of the 33Bu polymer was found to be oriented parallel to the surface normal. This research shows that SFG is a useful analytical technique which provides unique details regarding the interaction mechanisms of these membrane-active copolymers and lipid bilayers.
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Affiliation(s)
- Christopher W Avery
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
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16
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Avery CW, Som A, Xu Y, Tew GN, Chen Z. Dependence of Antimicrobial Selectivity and Potency on Oligomer Structure Investigated Using Substrate Supported Lipid Bilayers and Sum Frequency Generation Vibrational Spectroscopy. Anal Chem 2009; 81:8365-72. [DOI: 10.1021/ac901271f] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Christopher W. Avery
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01002, and PolyMedix, Inc., Radnor, Pennsylvania 19087
| | - Abhigyan Som
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01002, and PolyMedix, Inc., Radnor, Pennsylvania 19087
| | - Yongjiang Xu
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01002, and PolyMedix, Inc., Radnor, Pennsylvania 19087
| | - Gregory N. Tew
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01002, and PolyMedix, Inc., Radnor, Pennsylvania 19087
| | - Zhan Chen
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01002, and PolyMedix, Inc., Radnor, Pennsylvania 19087
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17
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Polly R, Schimmelpfennig B, Flörsheimer M, Kruse K, AbdElMonem A, Klenze R, Rauhut G, Fanghänel T. Theoretical investigation of the water/corundum (0001) interface. J Chem Phys 2009; 130:064702. [DOI: 10.1063/1.3052074] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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18
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Flörsheimer M, Kruse K, Polly R, Abdelmonem A, Schimmelpfennig B, Klenze R, Fanghänel T. Hydration of mineral surfaces probed at the molecular level. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:13434-13439. [PMID: 18980345 DOI: 10.1021/la801677y] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
By employing the nonlinear optical, interface selective experiment of sum frequency spectroscopy together with independent ab initio and density functional theory calculations, we determine the functional species of a corundum (001) surface: doubly coordinated OH groups which differ in their bond tilt angles. The interaction of the functional species with the adjacent water molecules is also observed. In a large pH range around the point of zero charge, the interaction is not controlled electrostatically but by hydrogen bonding. The functional species' tilt angles are crucial parameters, determining whether the species act as hydrogen bond donors or acceptors.
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Affiliation(s)
- Mathias Flörsheimer
- Institute for Nuclear Waste Disposal, Research Centre Karlsruhe, Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany.
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19
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Even MA, Wang J, Chen Z. Structural information of mussel adhesive protein Mefp-3 acquired at various polymer/Mefp-3 solution interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:5795-801. [PMID: 18459751 DOI: 10.1021/la800138x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Mytilus edulis foot protein Mefp-3 serves as a primer in the formation of adhesive plaques that attach the mussel to solid surfaces in its immediate environment. The adsorption behavior of this protein on various materials of different hydrophobicity was studied using sum frequency generation (SFG) vibrational spectroscopy. By collecting SFG signals from side chains of these amino acids and from secondary structures of the protein, we have determined that this protein adopts different conformations at different interfaces, depending on hydrophobicity of the contact medium and specific chemical group interactions. We have also demonstrated that SFG has the potential to track the interfacial conformations of a single amino acid in a protein.
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Affiliation(s)
- Mark A Even
- Department of Chemistry, 930 North University Avenue, University of Michigan, Ann Arbor, MI 48109, USA
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20
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Krauland EM, Peelle BR, Wittrup KD, Belcher AM. Peptide tags for enhanced cellular and protein adhesion to single-crystalline sapphire. Biotechnol Bioeng 2007; 97:1009-20. [PMID: 17238208 DOI: 10.1002/bit.21341] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In order to facilitate a novel means for coupling proteins to metal oxides, peptides were identified from a dodecamer peptide yeast surface display library that bound a model metal oxide material, the C, A, and R crystalline faces of synthetic sapphire (alpha-Al(2)O(3)). Seven rounds of screening yielded peptides enriched in basic amino acids compared to the naive library. While the C-face had a high background of endogenous yeast cell binding, the A- and R faces displayed clear peptide-mediated cell adhesion. Cell detachment assays showed that cell adhesion strength correlated positively with increasing basicity of expressed peptides. Cell adhesion was also shown to be sensitive to buffer ionic strength as well as incubation with soluble peptide (with half maximal inhibition of cell binding at approximately 5 microM peptide). Next, dodecamer peptides cloned into yeast showed that lysine led to stronger interactions than arginine, and that charge distribution affected adhesion strength. We postulate binding to arise from peptide geometries that permit conformation alignment of the basic amino acids towards the surface so that the charged groups can undergo local electrostatic interactions with the surface oxide. Lastly, peptide K1 (-(GK)(6)) was cloned onto the c-terminus of maltose binding protein (MBP) and the resultant mutant protein showed a half-maximal binding at approximately 10(-7)-10(-6) M, which marked a approximately 500- to 1,000-fold binding improvement to sapphire's A-face as compared with wild-type MBP. Targeting proteins to metal oxide surfaces with peptide tags may provide a facile one-step alternative coupling chemistry for the formation of protein bioassays and biosensors.
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Affiliation(s)
- Eric M Krauland
- Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
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21
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Ma G, Allen HC. DPPC Langmuir monolayer at the air-water interface: probing the tail and head groups by vibrational sum frequency generation spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:5341-9. [PMID: 16732662 DOI: 10.1021/la0535227] [Citation(s) in RCA: 224] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Dipalmitoylphosphatidylcholine (DPPC) is the predominant lipid component in lung surfactant. In this study, the Langmuir monolayer of deuterated dipalmitoylphosphatidylcholine (DPPC-d62) in the liquid-expanded (LE) phase and the liquid-condensed (LC) phase has been investigated at the air-water interface with broad bandwidth sum frequency generation (BBSFG) spectroscopy combined with a Langmuir film balance. Four moieties of the DPPC molecule are probed by BBSFG: the terminal methyl (CD3) groups of the tails, the methylene (CD2) groups of the tails, the choline methyls (CH3) in the headgroup, and the phosphate in the headgroup. BBSFG spectra of the four DPPC moieties provide information about chain conformation, chain orientation, headgroup orientation, and headgroup hydration. These results provide a comprehensive picture of the DPPC phase behavior at the air-water interface. In the LE phase, the DPPC hydrocarbon chains are conformationally disordered with a significant number of gauche configurations. In the LC phase, the hydrocarbon chains are in an all-trans conformation and are tilted from the surface normal by 25 degrees. In addition, the orientations of the tail terminal methyl groups are found to remain nearly unchanged with the variation of surface area. Qualitative analysis of the BBSFG spectra of the choline methyl groups suggests that these methyl groups are tilted but lie somewhat parallel to the surface plane in both the LE and LC phases. The dehydration of the phosphate headgroup due to the LE-LC phase transition is observed through the frequency blue shift of the phosphate symmetric stretch in the fingerprint region. In addition, implications for lung surfactant function from this work are discussed.
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Affiliation(s)
- Gang Ma
- Department of Chemistry, Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, USA
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Xu M, Liu D, Allen HC. Ethylenediamine at air/liquid and air/silica interfaces: protonation versus hydrogen bonding investigated by sum frequency generation spectroscopy. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2006; 40:1566-72. [PMID: 16568771 DOI: 10.1021/es051537l] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The adsorption process on mineral oxide surfaces is one of the most important factors influencing the migration and distribution of contaminants in the environment. Although there have been numerous studies carried out at the macroscopic scale, there is a lack of molecular-scale interfacial information. The molecular-scale information is often crucial for the determination of sorption mechanisms. In this study, sum frequency generation spectroscopy (SFG), a surface specific vibrational spectroscopy, has been employed to investigate the adsorption of ethylenediamine (H2N(CH2)2NH2, EDA) onto the amorphous SiO2 surface and EDA protonated products at air/liquid interfaces. The SFG spectra of EDA adsorbed on the silica surface and the singly protonated EDA solution are similar in both CH and NH stretching regions. These spectral similarities indicate that EDA molecules are strongly chemisorbed to the silica surface through the protonation of one EDA amine group by surface silanol OH groups, thereby forming a (H2N(CH2)2NH3)+(O-Si[triple bond])- surface complex. The SFG results also indicate that the surface acidity of the silanol OH groups (pKa (HOSi[triple bond])) is between the two pKa values of EDA (in the range of 7.56-10.71) at the air/silica interface.
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Affiliation(s)
- Man Xu
- Department of Chemistry, The Ohio State University, 100 West 18th Ave., Columbus, Ohio 43210, USA
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Liu D, Ma G, Allen HC. Adsorption of 4-picoline and piperidine to the hydrated SiO2 surface: probing the surface acidity with vibrational sum frequency generation spectroscopy. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2005; 39:2025-32. [PMID: 15871233 DOI: 10.1021/es0482280] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Vapor adsorption is an important process influencing the migration and the fate of many organic pollutants in the environment. In this study, vibrational sum frequency generation (SFG) spectroscopy was used to study the adsorption of two surface acidity probe molecules, 4-picoline (pKa = 5.94) and piperidine (pKa = 11.24), onto the amorphous SiO2 surface. The adsorption of 4-picoline onto the silica surface occurs by forming weak hydrogen bonds between the nitrogen atoms of 4-picoline molecules and the hydrogen atoms of surface silanol OH groups. Piperidine molecules are strongly chemisorbed onto the SiO2 surface through the protonation of piperidine molecules by surface silanol OH groups. The SFG results indicate that the surface acidity constant of silanol OH groups (pKa-(HOSi triple bond)) is in the range of 5.94-11.24 at the air/solid interface. Although this range of surface acidity constants is quite wide, it is possible to narrow it by choosing probe molecules with a smaller pKa range. Together with theoretical prediction methods, adsorption studies using vibrational SFG spectroscopy are capable of quantifying the surface acidity of mineral oxides by carefully choosing the acidity probe molecules.
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Affiliation(s)
- Dingfang Liu
- Department of Chemistry, The Ohio State University, Columbus, Ohio 43210, USA
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