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Marquardt D, van Oosten B, Dziura M, Long JR, Harroun TA. The interaction and orientation of Peptide KL 4 in model membranes. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183893. [PMID: 35219719 DOI: 10.1016/j.bbamem.2022.183893] [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: 11/01/2021] [Revised: 01/18/2022] [Accepted: 02/11/2022] [Indexed: 06/14/2023]
Abstract
We report on the orientation and location of synthetic pulmonary surfactant peptide KL4, (KLLLL)4K, in model lipid membranes. The partitioning depths of selectively deuterated leucine residues within KL4 were determined in DPPC:POPG (4:1) and POPC:POPG (4:1) bilayers by oriented neutron diffraction. These measurements were combined with an NMR-generated model of the peptide structure to determine the orientation and partitioning of the peptide at the lipid-water interface. The results demonstrate KL4 adopting an orientation that interacts with a single membrane leaflet. These observations are consistent with past 2H NMR and EPR studies (Antharam et al., 2009; Turner et al., 2014).
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Affiliation(s)
- Drew Marquardt
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada; Department of Physics, University of Windsor, Windsor, Ontario, Canada.
| | - Brad van Oosten
- Department of Physics, Brock University, St. Catharines, Ontario, Canada
| | - Maksymilian Dziura
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada
| | - Joanna R Long
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, USA
| | - Thad A Harroun
- Department of Physics, Brock University, St. Catharines, Ontario, Canada.
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2
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Tran NT, Mentink-Vigier F, Long JR. Dynamic Nuclear Polarization of Biomembrane Assemblies. Biomolecules 2020; 10:E1246. [PMID: 32867275 PMCID: PMC7565305 DOI: 10.3390/biom10091246] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/10/2020] [Accepted: 08/11/2020] [Indexed: 01/02/2023] Open
Abstract
While atomic scale structural and dynamic information are hallmarks of nuclear magnetic resonance (NMR) methodologies, sensitivity is a fundamental limitation in NMR studies. Fully exploiting NMR capabilities to study membrane proteins is further hampered by their dilution within biological membranes. Recent developments in dynamic nuclear polarization (DNP), which can transfer the relatively high polarization of unpaired electrons to nuclear spins, show promise for overcoming the sensitivity bottleneck and enabling NMR characterization of membrane proteins under native-like conditions. Here we discuss fundamental aspects of DNP-enhanced solid-state NMR spectroscopy, experimental details relevant to the study of lipid assemblies and incorporated proteins, and sensitivity gains which can be realized in biomembrane-based samples. We also present unique insights which can be gained from DNP measurements and prospects for further development of the technique for elucidating structures and orientations of membrane proteins in native lipid environments.
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Affiliation(s)
- Nhi T. Tran
- Department of Chemistry, University of Florida, Gainesville, FL 32611, USA;
| | - Frédéric Mentink-Vigier
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA;
| | - Joanna R. Long
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA;
- Department of Biochemistry & Molecular Biology and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
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3
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Qiu Y, Chow MYT, Liang W, Chung WWY, Mak JCW, Lam JKW. From Pulmonary Surfactant, Synthetic KL4 Peptide as Effective siRNA Delivery Vector for Pulmonary Delivery. Mol Pharm 2017; 14:4606-4617. [PMID: 29121767 DOI: 10.1021/acs.molpharmaceut.7b00725] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Pulmonary delivery of small interfering RNA (siRNA) has huge potential for the treatment of a wide range of respiratory diseases. The ability of naked siRNA to transfect cells in the lungs without a delivery vector has prompted the investigation of whether an endogenous component is at least partially responsible for the cellular uptake of siRNA, and whether a safe and efficient delivery system could be developed from this component to further improve the transfection efficiency. Surfactant protein B (SP-B), a positively charged protein molecule found in lung surfactant, is one of the possible candidates. While the role of SP-B in siRNA transfection remains to be determined, the SP-B mimic, synthetic KL4 peptide, was investigated in this study as a potential siRNA carrier. KL4 is a 21-residue cationic peptide that was able to bind to siRNA to form nanosized complexes. It mediated siRNA transfection effectively in vitro on human lung epithelial cells, A549 cells, and BEAS-2B cells, which was comparable to Lipofectamine 2000. When commercial pulmonary surfactant (Infasurf) was added in the transfection medium, the gene silencing effect of siRNA in cells transfected with Lipofectamine 2000 was completely abolished, whereas those transfected with KL4 remained unaffected. At 4 °C, KL4 failed to deliver siRNA into the cells, indicating that an energy-dependent process was involved in the uptake of the complexes. Chlorpromazine (inhibitor of chathrin-mediated endocytosis), but not nystatin (inhibitor of caveolae-mediated endocytosis), inhibited the uptake of KL4/siRNA complexes, suggesting that they entered cells through clathrin-mediated endocytosis. There was no sign of cytotoxicity or immune response caused by KL4 and KL4/siRNA complexes. Overall, this study demonstrated that synthetic KL4 peptide is a promising candidate for siRNA carrier for pulmonary delivery and could be a potential platform for delivering other types of nucleic acid therapeutics.
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Affiliation(s)
- Yingshan Qiu
- Department of Pharmacology & Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong , 21 Sassoon Road, Pokfulam, Hong Kong
| | - Michael Y T Chow
- Department of Pharmacology & Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong , 21 Sassoon Road, Pokfulam, Hong Kong
| | - Wanling Liang
- Department of Pharmacology & Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong , 21 Sassoon Road, Pokfulam, Hong Kong
| | - Winnie W Y Chung
- Department of Pharmacology & Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong , 21 Sassoon Road, Pokfulam, Hong Kong
| | - Judith C W Mak
- Department of Pharmacology & Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong , 21 Sassoon Road, Pokfulam, Hong Kong.,Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong , 21 Sassoon Road, Pokfulam, Hong Kong
| | - Jenny K W Lam
- Department of Pharmacology & Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong , 21 Sassoon Road, Pokfulam, Hong Kong
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Ferreira HE, Drobny GP. Solid state deuterium NMR study of LKα14 peptide aggregation in biosilica. Biointerphases 2017; 12:02D418. [PMID: 28655279 PMCID: PMC5552403 DOI: 10.1116/1.4986907] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 05/26/2017] [Accepted: 06/07/2017] [Indexed: 11/17/2022] Open
Abstract
In nature, organisms including diatoms, radiolaria, and marine sponges use proteins, long chain polyamines, and other organic molecules to regulate the assembly of complex silica-based structures. Here, the authors investigate structural features of small peptides, designed to mimic the silicifying activities of larger proteins found in natural systems. LKα14 (Ac-LKKLLKLLKKLLKL-C), an amphiphilic lysine/leucine repeat peptide with an α-helical secondary structure at polar/apolar interfaces, coprecipitates with silica to form nanospheres. Previous 13C magic angle spinning studies suggest that the tetrameric peptide bundles that LKα14 is known to form in solution may persist in the silica-complexed form, and may also function as catalysts and templates for silica formation. To further investigate LKα14 aggregation in silica, deuterium solid-state nuclear magnetic resonance (2H ssNMR) was used to establish how leucine side-chain dynamics differ in solid LKα14 peptides isolated from aqueous solution, from phosphate-buffered solution, and in the silica-precipitated states. Modeling the 2H ssNMR line shapes probed the mechanisms of peptide preaggregation and silica coprecipitation. The resulting NMR data indicates that the peptide bundles in silica preserve the hydrophobic interior that they display in the hydrated solid state. However, NMR data also indicate free motion of the leucine residues in silica, a condition that may result from structural deformation of the aggregates arising from interactions between the surface lysine side chains and the surrounding silica matrix.
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Affiliation(s)
- Helen E Ferreira
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195
| | - Gary P Drobny
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195
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5
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Echaide M, Autilio C, Arroyo R, Perez-Gil J. Restoring pulmonary surfactant membranes and films at the respiratory surface. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:1725-1739. [PMID: 28341439 DOI: 10.1016/j.bbamem.2017.03.015] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 03/14/2017] [Accepted: 03/19/2017] [Indexed: 02/08/2023]
Abstract
Pulmonary surfactant is a complex of lipids and proteins assembled and secreted by the alveolar epithelium into the thin layer of fluid coating the respiratory surface of lungs. There, surfactant forms interfacial films at the air-water interface, reducing dramatically surface tension and thus stabilizing the air-exposed interface to prevent alveolar collapse along respiratory mechanics. The absence or deficiency of surfactant produces severe lung pathologies. This review describes some of the most important surfactant-related pathologies, which are a cause of high morbidity and mortality in neonates and adults. The review also updates current therapeutic approaches pursuing restoration of surfactant operative films in diseased lungs, mainly through supplementation with exogenous clinical surfactant preparations. This article is part of a Special Issue entitled: Membrane Lipid Therapy: Drugs Targeting Biomembranes edited by Pablo V. Escribá.
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Affiliation(s)
- Mercedes Echaide
- Dept. Biochemistry, Faculty of Biology, and Research Institute "Hospital 12 de Octubre", Complutense University, Madrid, Spain
| | - Chiara Autilio
- Dept. Biochemistry, Faculty of Biology, and Research Institute "Hospital 12 de Octubre", Complutense University, Madrid, Spain
| | - Raquel Arroyo
- Dept. Biochemistry, Faculty of Biology, and Research Institute "Hospital 12 de Octubre", Complutense University, Madrid, Spain
| | - Jesus Perez-Gil
- Dept. Biochemistry, Faculty of Biology, and Research Institute "Hospital 12 de Octubre", Complutense University, Madrid, Spain.
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6
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Braide-Moncoeur O, Tran NT, Long JR. Peptide-based synthetic pulmonary surfactant for the treatment of respiratory distress disorders. Curr Opin Chem Biol 2016; 32:22-8. [DOI: 10.1016/j.cbpa.2016.02.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 02/18/2016] [Accepted: 02/21/2016] [Indexed: 12/31/2022]
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7
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Peng B, Ding XY, Sun C, Liu W, Zhang JZH, Zhao X. The effect of POPC acyl chains packing by aromatic amino acid methyl esters investigated by ATR-FTIR combined with QM calculations. RSC Adv 2016. [DOI: 10.1039/c6ra05903a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The packing of POPC acyl chains can be influenced by aromatic amino acid methyl esters significantly, thus the HCCH motif is packed closed to the other one of an adjacent acyl chain with enhancement by dispersion interactions.
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Affiliation(s)
- Bo Peng
- Shanghai Key Laboratory of Magnetic Resonance
- Department of Physics
- School of Physics and Materials Science
- East China Normal University
- Shanghai 200062
| | - Xiao-Yan Ding
- Shanghai Key Laboratory of Magnetic Resonance
- Department of Physics
- School of Physics and Materials Science
- East China Normal University
- Shanghai 200062
| | - Chao Sun
- Shanghai Key Laboratory of Magnetic Resonance
- Department of Physics
- School of Physics and Materials Science
- East China Normal University
- Shanghai 200062
| | - Wei Liu
- State Key Laboratory of Precision Spectroscopy
- Department of Physics
- School of Physics and Materials Science
- East China Normal University
- Shanghai 200062
| | - John Z. H. Zhang
- State Key Laboratory of Precision Spectroscopy
- Department of Physics
- School of Physics and Materials Science
- East China Normal University
- Shanghai 200062
| | - Xin Zhao
- Shanghai Key Laboratory of Magnetic Resonance
- Department of Physics
- School of Physics and Materials Science
- East China Normal University
- Shanghai 200062
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Meirovitch E, Liang Z, Freed JH. Protein Dynamics in the Solid State from (2)H NMR Line Shape Analysis. II. MOMD Applied to C-D and C-CD3 Probes. J Phys Chem B 2015; 119:14022-32. [PMID: 26402431 PMCID: PMC4676681 DOI: 10.1021/acs.jpcb.5b07434] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Deuterium
line shape analysis from mobile C–D and C–CD3 groups has emerged as a particularly useful tool for studying
dynamics in the solid state. The theoretical models devised so far
consist typically of sets of independent dynamic modes. Each such
mode is simple and usually case-specific. In this scenario, model
improvement entails adding yet another mode (thereby changing the
overall model), comparison of different cases is difficult, and ambiguity
is unavoidable. We recently developed the microscopic order macroscopic
disorder (MOMD) approach as a single-mode alternative. In MOMD, the
local spatial restrictions are expressed by an anisotropic potential,
the local motion by a diffusion tensor, and the local molecular geometry
by relative (magnetic and model-related) tensor orientations, all
of adjustable symmetry. This approach provides a consistent method
of analysis, thus resolving the issues above. In this study, we apply
MOMD to PS-adsorbed LKα14 peptide and dimethylammonium tetraphenylborate
(C–CD3 and N–CD3 dynamics, respectively),
as well as HhaI methyltransferase target DNA and
phase III of benzene-6-hexanoate (C–D dynamics). The success
with fitting these four disparate cases, as well as the two cases
in the previous report, demonstrates the generality of this MOMD-based
approach. In this study, C–D and C–CD3 are
both found to execute axial diffusion (rates R⊥ and R∥) in the
presence of a rhombic potential given by the L =
2 spherical harmonics (coefficients c02 and c22). R⊥ (R∥) is in the 102–103 (104–105) s–1 range, and c02 and c22 are on the
order of 2–3 kBT. Specific parameter values are determined for each mobile site.
The diffusion and quadrupolar tensors are tilted at either 120°
(consistent with trans–gauche isomerization) or nearly 110.5° (consistent with methyl exchange).
Future prospects include extension of the MOMD formalism to include
MAS, and application to 15N and 13C nuclei.
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Affiliation(s)
- Eva Meirovitch
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University , Ramat-Gan 52900, Israel
| | - Zhichun Liang
- Baker Laboratory of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853-1301, United States
| | - Jack H Freed
- Baker Laboratory of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853-1301, United States
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9
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Smith AN, Caporini MA, Fanucci GE, Long JR. A Method for Dynamic Nuclear Polarization Enhancement of Membrane Proteins. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201410249] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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10
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Smith AN, Caporini MA, Fanucci GE, Long JR. A method for dynamic nuclear polarization enhancement of membrane proteins. Angew Chem Int Ed Engl 2014; 54:1542-6. [PMID: 25504310 DOI: 10.1002/anie.201410249] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Indexed: 12/29/2022]
Abstract
Dynamic nuclear polarization (DNP) magic-angle spinning (MAS) solid-state NMR (ssNMR) spectroscopy has the potential to enhance NMR signals by orders of magnitude and to enable NMR characterization of proteins which are inherently dilute, such as membrane proteins. In this work spin-labeled lipid molecules (SL-lipids), when used as polarizing agents, lead to large and relatively homogeneous DNP enhancements throughout the lipid bilayer and to an embedded lung surfactant mimetic peptide, KL4 . Specifically, DNP MAS ssNMR experiments at 600 MHz/395 GHz on KL4 reconstituted in liposomes containing SL-lipids reveal DNP enhancement values over two times larger for KL4 compared to liposome suspensions containing the biradical TOTAPOL. These findings suggest an alternative sample preparation strategy for DNP MAS ssNMR studies of lipid membranes and integral membrane proteins.
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Affiliation(s)
- Adam N Smith
- Department of Chemistry, University of Florida, 214 Leigh Hall Gainesville, FL 32611-7200 (USA)
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Turner AL, Braide O, Mills FD, Fanucci GE, Long JR. Residue specific partitioning of KL4 into phospholipid bilayers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:3212-9. [DOI: 10.1016/j.bbamem.2014.09.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 08/24/2014] [Accepted: 09/15/2014] [Indexed: 01/14/2023]
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12
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Zane AC, Michelet C, Roehrich A, Emani PS, Drobny GP. Silica morphogenesis by lysine-leucine peptides with hydrophobic periodicity. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:7152-7161. [PMID: 24896500 DOI: 10.1021/la501444t] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The use of biomimetic approaches in the production of inorganic nanostructures is of great interest to the scientific and industrial community due to the relatively moderate physical conditions needed. In this vein, taking cues from silaffin proteins used by unicellular diatoms, several studies have identified peptide candidates for the production of silica nanostructures. In the current article, we study intensively one such silica-precipitating peptide, LKα14 (Ac-LKKLLKLLKKLLKL-c), an amphiphilic lysine/leucine repeat peptide that self-organizes into an α-helical secondary structure under appropriate concentration and buffer conditions. The suggested mechanism of precipitation is that the sequestration of hydrophilic lysines on one side of this helix allows interaction with the negatively charged surface of silica nanoparticles, which in turn can aggregate further into larger structures. To investigate the process, we carry out 1D and 2D solid-state NMR (ssNMR) studies on samples with one or two uniformly (13)C- and (15)N-labeled residues to determine the backbone and side-chain chemical shifts. We also further study the dynamics of two leucine residues in the sequence through (13)C spin-lattice relaxation times (T1) to determine the impact of silica coprecipitation on their mobility. Our results confirm the α-helical secondary structure in both the neat and silica-complexed states of the peptide, and the patterns of chemical shift and relaxation time changes between the two states suggest possible mechanisms of self-aggregation and silica precipitation.
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Affiliation(s)
- Ariel C Zane
- Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195, United States
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13
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Wolfson MR, Wu J, Hubert TL, Gregory TJ, Mazela J, Shaffer TH. Lucinactant attenuates pulmonary inflammatory response, preserves lung structure, and improves physiologic outcomes in a preterm lamb model of RDS. Pediatr Res 2012; 72:375-83. [PMID: 22821059 PMCID: PMC3888789 DOI: 10.1038/pr.2012.96] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Acute inflammatory responses to supplemental oxygen and mechanical ventilation have been implicated in the pathophysiological sequelae of respiratory distress syndrome (RDS). Although surfactant replacement therapy (SRT) has contributed to lung stability, the effect on lung inflammation is inconclusive. Lucinactant contains sinapultide (KL4), a novel synthetic peptide that functionally mimics surfactant protein B, a protein with anti-inflammatory properties. We tested the hypothesis that lucinactant may modulate lung inflammatory response to mechanical ventilation in the management of RDS and may confer greater protection than animal-derived surfactants. METHODS Preterm lambs (126.8 ± 0.2 SD d gestation) were randomized to receive lucinactant, poractant alfa, beractant, or no surfactant and studied for 4 h. Gas exchange and pulmonary function were assessed serially. Lung inflammation biomarkers and lung histology were assessed at termination. RESULTS SRT improved lung compliance relative to no SRT without significant difference between SRT groups. Lucinactant attenuated lung and systemic inflammatory response, supported oxygenation at lower ventilatory requirements, and preserved lung structural integrity to a greater degree than either no SRT or SRT with poractant alfa or beractant. CONCLUSION These data suggest that early intervention with lucinactant may more effectively mitigate pulmonary pathophysiological sequelae of RDS than the animal-derived surfactants poractant alfa or beractant.
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Affiliation(s)
- Marla R. Wolfson
- Department of Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania,Department of Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania,Departments of Pediatrics, Temple University School of Medicine, Philadelphia, Pennsylvania,Center for Inflammation, Translational, and Clinical Lung Research, Temple University School of Medicine, Philadelphia, Pennsylvania
| | - Jichuan Wu
- Department of Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania,Center for Inflammation, Translational, and Clinical Lung Research, Temple University School of Medicine, Philadelphia, Pennsylvania
| | - Terrence L. Hubert
- Department of Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania
| | | | - Jan Mazela
- Discovery Laboratories, Inc., Warrington, Pennsylvania,Poznan University of Medical Sciences, Poznan, Poland
| | - Thomas H. Shaffer
- Department of Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania,Departments of Pediatrics, Temple University School of Medicine, Philadelphia, Pennsylvania,Center For Pediatric Research, Alfred I. duPont Hospital for Children, Wilmington, Delaware
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14
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Holten-Andersen N, Michael Henderson J, Walther FJ, Waring AJ, Ruchala P, Notter RH, Lee KYC. KL₄ peptide induces reversible collapse structures on multiple length scales in model lung surfactant. Biophys J 2011; 101:2957-65. [PMID: 22208194 DOI: 10.1016/j.bpj.2011.10.050] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 09/27/2011] [Accepted: 10/06/2011] [Indexed: 10/14/2022] Open
Abstract
We investigated the effects of KL₄, a 21-residue amphipathic peptide approximating the overall ratio of positively charged to hydrophobic amino acids in surfactant protein B (SP-B), on the structure and collapse of dipalmitoylphosphatidylcholine and palmitoyl-oleoyl-phosphatidylglycerol monolayers. As reported in prior work on model lung surfactant phospholipid films containing SP-B and SP-B peptides, our experiments show that KL₄ improves surfactant film reversibility during repetitive interfacial cycling in association with the formation of reversible collapse structures on multiple length scales. Emphasis is on exploring a general mechanistic connection between peptide-induced nano- and microscale reversible collapse structures (silos and folds).
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Affiliation(s)
- Niels Holten-Andersen
- Department of Chemistry, Institute for Biophysical Dynamics, and the James Franck Institute, University of Chicago, Chicago, Illinois, USA
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15
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Breen NF, Li K, Olsen GL, Drobny GP. Deuterium magic angle spinning NMR used to study the dynamics of peptides adsorbed onto polystyrene and functionalized polystyrene surfaces. J Phys Chem B 2011; 115:9452-60. [PMID: 21650191 DOI: 10.1021/jp1101829] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
LKα14 is a 14 amino acid peptide with a periodic sequence of leucine and lysine residues consistent with an amphipathic α-helix. This "hydrophobic periodicity" has been found to result in an α-helical secondary structure at air-water interfaces and on both polar and nonpolar solid polymer surfaces. In this paper, the dynamics of LKα14 peptides, selectively deuterated at a single leucine and adsorbed onto polystyrene and carboxylated polystyrene beads, are studied using (2)H magic angle spinning (MAS) solid state NMR over a 100 °C temperature range. We first demonstrate the sensitivity enhancement possible with (2)H MAS techniques, which in turn enables us to obtain high-quality (2)H NMR spectra for selectively deuterated peptides adsorbed onto solid polymer surfaces. The extensive literature shows that the dynamics of leucine side chains are sensitive to the local structural environment of the protein. Therefore, the degree to which the dynamics of leucine side chains and the backbone of the peptide LKα14 are influenced by surface proximity and surface chemistry is studied as a function of temperature with (2)H MAS NMR. It is found that the dynamics of the leucine side chains in LKα14 depend strongly upon the orientation of the polymer on the surface, which in turn depends on whether the LKα14 peptide adsorbs onto a polar or nonpolar surface. (2)H MAS line shapes therefore permit probes of surface orientation over a wide temperature range.
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Affiliation(s)
- Nicholas F Breen
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
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16
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Sum frequency generation and solid-state NMR study of the structure, orientation, and dynamics of polystyrene-adsorbed peptides. Proc Natl Acad Sci U S A 2010; 107:13288-93. [PMID: 20628016 DOI: 10.1073/pnas.1003832107] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The power of combining sum frequency generation (SFG) vibrational spectroscopy and solid-state nuclear magnetic resonance (ssNMR) spectroscopy to quantify, with site specificity and atomic resolution, the orientation and dynamics of side chains in synthetic model peptides adsorbed onto polystyrene (PS) surfaces is demonstrated in this study. Although isotopic labeling has long been used in ssNMR studies to site-specifically probe the structure and dynamics of biomolecules, the potential of SFG to probe side chain orientation in isotopically labeled surface-adsorbed peptides and proteins remains largely unexplored. The 14 amino acid leucine-lysine peptide studied in this work is known to form an alpha-helical secondary structure at liquid-solid interfaces. Selective, individual deuteration of the isopropyl group in each leucine residue was used to probe the orientation and dynamics of each individual leucine side chain of LKalpha14 adsorbed onto PS. The selective isotopic labeling methods allowed SFG analysis to determine the orientations of individual side chains in adsorbed peptides. Side chain dynamics were obtained by fitting the deuterium ssNMR line shape to specific motional models. Through the combined use of SFG and ssNMR, the dynamic trends observed for individual side chains by ssNMR have been correlated with side chain orientation relative to the PS surface as determined by SFG. This combination provides a more complete and quantitative picture of the structure, orientation, and dynamics of these surface-adsorbed peptides than could be obtained if either technique were used separately.
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