1
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Ismail VS, Britt HM, Mosely JA, Sanderson JM. Peptide lipidation in lysophospholipid micelles and lysophospholipid-enriched membranes. Faraday Discuss 2021; 232:282-294. [PMID: 34555137 DOI: 10.1039/d1fd00030f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Acyl transfer from lipids to membrane-associated peptides is a well-documented process, leading to the generation of a lipidated peptide and a lysolipid. In this article, we demonstrate that acyl transfer from lysophosphatidylcholines (lysoPCs) to the peptide melittin also occurs, both in micelles of pure lysolipid and in lipid/lysolipid mixtures. In the case of bilayers containing lysolipids, acyl transfer from the lysolipid is marginally favoured over transfer from the lipid. In pure bilayers of saturated lipids, the introduction of even small amounts of lysolipid appears to significantly increase the reactivity towards lipidation.
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Affiliation(s)
- Vian S Ismail
- Chemistry Department, Durham University, Durham, DH1 3LE, UK.
| | - Hannah M Britt
- Chemistry Department, Durham University, Durham, DH1 3LE, UK.
| | - Jackie A Mosely
- National Horizons Centre, School of Health & Life Sciences, Teesside University, Darlington, DL1 1HG, UK.
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2
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Oskolkova OV, Hodzic A, Karki P, Gesslbauer B, Ke Y, Hofer DC, Bogner-Strauss JG, Galano JM, Oger C, Birukova A, Durand T, Birukov K, Bochkov V. Oxidized phospholipids on alkyl-amide scaffold demonstrate anti-endotoxin and endothelial barrier-protective properties. Free Radic Biol Med 2021; 174:264-271. [PMID: 34371153 DOI: 10.1016/j.freeradbiomed.2021.07.041] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 07/25/2021] [Accepted: 07/31/2021] [Indexed: 01/26/2023]
Abstract
Oxidized phospholipids (OxPLs) containing enzymatically or non-enzymatically oxidized fatty acids (oxylipins) are increasingly recognized as lipid mediators involved in pathogenesis of diseases. Further understanding of structure-activity relationship and molecular mechanisms activated by OxPLs is hampered by the complexity of synthesis of individual molecular species. Although dozens of individual free oxylipins are commercially available, their attachment to the phospholipid scaffold requires relatively harsh conditions during activation of carboxy-group, which may lead to decomposition of unstable oxylipins. Furthermore, additional protection-deprotection steps are required for oxylipins containing hydroxy-groups. In this work we describe synthesis of OxPLs containing oxylipins bound at the sn-2-position via an amide-bond that is characteristic of sphingophospholipids. Activation of oxylipins and attachment to the phospholipid scaffold are performed under mild conditions and characterized by high yield. Hydroxy-groups of oxylipins do not interfere with reactions and therefore no protection/deprotection steps are needed. In order to prevent oxylipin migration, a fatty acid residue at the sn-1 was bound through an alkyl bond, which is a common bond present in a large proportion of naturally occurring phospholipids. An additional advantage of combining alkyl and amide bonds in a single phospholipid molecule is that both types of bonds are phospholipase A1/A2-resistant, which may be expected to improve biological stability of OxPLs and thus simplify analysis of their effects. As proof of principle, several alkyl-amide oxidized phosphatidylcholines (OxPCs) containing either linear or prostane ring oxylipins have been synthesized. Importantly, we show here that alkyl-amide-OxPCs demonstrated biological activities similar to those of di-acyl-OxPCs. Alkyl-amide-OxPCs inhibited pro-inflammatory action of LPS and increased endothelial cellular barrier in vitro and in mouse models. The effects of alkyl-amide and di-acyl-OxPCs developed in a similar range of concentrations. We hypothesize that alkyl-amide-OxPLs may become a useful tool for deeper analysis of the structure-activity relationship of OxPLs.
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Affiliation(s)
- Olga V Oskolkova
- Institute of Pharmaceutical Sciences, Division of Pharmaceutical Chemistry, University of Graz, Humboldtstrasse 46/III, 8010, Graz, Austria.
| | - Alma Hodzic
- Institute of Pharmaceutical Sciences, Division of Pharmaceutical Chemistry, University of Graz, Humboldtstrasse 46/III, 8010, Graz, Austria.
| | - Pratap Karki
- Department of Anesthesiology, University of Maryland School of Medicine, 20 Penn. Street, HSF-2, Room 145, Baltimore, MD, 21201, USA.
| | - Bernd Gesslbauer
- Institute of Pharmaceutical Sciences, Division of Pharmaceutical Chemistry, University of Graz, Humboldtstrasse 46/III, 8010, Graz, Austria.
| | - Yunbo Ke
- Department of Anesthesiology, University of Maryland School of Medicine, 20 Penn. Street, HSF-2, Room 145, Baltimore, MD, 21201, USA.
| | - Dina C Hofer
- Institute of Biochemistry, Graz University of Technology, Humboldtstrasse 46/III, 8010, Graz, Austria.
| | - Juliane G Bogner-Strauss
- Institute of Biochemistry, Graz University of Technology, Humboldtstrasse 46/III, 8010, Graz, Austria.
| | - Jean-Marie Galano
- Institut des Biomolécules Max Mousseron IBMM, CNRS, ENSCM, Faculté de Pharmacie, Université de Montpellier, 15 Avenue Charles Flahault, BP14491, 34093, Montpellier Cedex05, France.
| | - Camille Oger
- Institut des Biomolécules Max Mousseron IBMM, CNRS, ENSCM, Faculté de Pharmacie, Université de Montpellier, 15 Avenue Charles Flahault, BP14491, 34093, Montpellier Cedex05, France.
| | - Anna Birukova
- Department of Anesthesiology, University of Maryland School of Medicine, 20 Penn. Street, HSF-2, Room 145, Baltimore, MD, 21201, USA.
| | - Thierry Durand
- Institut des Biomolécules Max Mousseron IBMM, CNRS, ENSCM, Faculté de Pharmacie, Université de Montpellier, 15 Avenue Charles Flahault, BP14491, 34093, Montpellier Cedex05, France.
| | - Konstantin Birukov
- Department of Anesthesiology, University of Maryland School of Medicine, 20 Penn. Street, HSF-2, Room 145, Baltimore, MD, 21201, USA.
| | - Valery Bochkov
- Institute of Pharmaceutical Sciences, Division of Pharmaceutical Chemistry, University of Graz, Humboldtstrasse 46/III, 8010, Graz, Austria; Field of Excellence BioHealth - University of Graz, Graz, Austria.
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3
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Karman AP, Ebeler SE, Nitin N, Dungan SR. Partitioning, solubility and solubilization of limonene into water or
short‐chain
phosphatidylcholine solutions. J AM OIL CHEM SOC 2021. [DOI: 10.1002/aocs.12535] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Andrew P. Karman
- Department of Chemical Engineering University of California, Davis Davis California USA
| | - Susan E. Ebeler
- Department of Viticulture and Enology University of California, Davis Davis California USA
| | - Nitin Nitin
- Department of Food Science and Technology University of California, Davis Davis California USA
- Department of Biological and Agricultural Engineering University of California, Davis Davis California USA
| | - Stephanie R. Dungan
- Department of Chemical Engineering University of California, Davis Davis California USA
- Department of Food Science and Technology University of California, Davis Davis California USA
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4
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Markovic M, Ben‐Shabat S, Keinan S, Aponick A, Zimmermann EM, Dahan A. Lipidic prodrug approach for improved oral drug delivery and therapy. Med Res Rev 2018; 39:579-607. [DOI: 10.1002/med.21533] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 07/26/2018] [Accepted: 07/27/2018] [Indexed: 12/13/2022]
Affiliation(s)
- Milica Markovic
- Department of Clinical PharmacologySchool of Pharmacy, Faculty of Health Sciences, Ben‐Gurion University of the NegevBeer‐Sheva Israel
| | - Shimon Ben‐Shabat
- Department of Clinical PharmacologySchool of Pharmacy, Faculty of Health Sciences, Ben‐Gurion University of the NegevBeer‐Sheva Israel
| | | | - Aaron Aponick
- Department of ChemistryUniversity of FloridaGainesville Florida
| | - Ellen M. Zimmermann
- Department of MedicineDivision of Gastroenterology, University of FloridaGainesville Florida
| | - Arik Dahan
- Department of Clinical PharmacologySchool of Pharmacy, Faculty of Health Sciences, Ben‐Gurion University of the NegevBeer‐Sheva Israel
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5
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Yunes Quartino PJ, Pusterla JM, Galván Josa VM, Fidelio GD, Oliveira RG. CNS myelin structural modification induced in vitro by phospholipases A2. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1858:123-9. [PMID: 26514604 DOI: 10.1016/j.bbamem.2015.10.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 10/22/2015] [Accepted: 10/23/2015] [Indexed: 12/13/2022]
Abstract
Myelin is the self-stacked membrane surrounding axons; it is also the target of several pathological and/or neurodegenerative processes like multiple sclerosis. These processes involve, among others, the hydrolytic attack by phospholipases. In this work we describe the changes in isolated myelin structure after treatment with several secreted PLA2 (sPLA2), by using small angle x-ray scattering (SAXS) measurements. It was observed that myelin treated with all the tested sPLA2s (from cobra and bee venoms and from pig pancreas) preserved the lamellar structure but displayed an enlarged separation between membranes in certain zones. Additionally, the peak due to membrane asymmetry was clearly enhanced. The coherence length was also lower than the non-treated myelin, indicating increased disorder. These SAXS results were complemented by Langmuir film experiments to follow myelin monolayer hydrolysis at the air/water interface by a decrease in electric surface potential at different surface pressures. All enzymes produced hydrolysis with no major qualitative difference between the isoforms tested.
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Affiliation(s)
- Pablo J Yunes Quartino
- Departamento de Química Biológica-CIQUIBIC (CONICET), Facultad de Ciencias Químicas, Universidad de Nacional de Córdoba, Haya de la Torre S/N, X5000HUA, Córdoba, Argentina
| | - Julio M Pusterla
- Departamento de Química Biológica-CIQUIBIC (CONICET), Facultad de Ciencias Químicas, Universidad de Nacional de Córdoba, Haya de la Torre S/N, X5000HUA, Córdoba, Argentina
| | - Victor M Galván Josa
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), FaMAF, Universidad Nacional de Córdoba, Argentina
| | - Gerardo D Fidelio
- Departamento de Química Biológica-CIQUIBIC (CONICET), Facultad de Ciencias Químicas, Universidad de Nacional de Córdoba, Haya de la Torre S/N, X5000HUA, Córdoba, Argentina
| | - Rafael G Oliveira
- Departamento de Química Biológica-CIQUIBIC (CONICET), Facultad de Ciencias Químicas, Universidad de Nacional de Córdoba, Haya de la Torre S/N, X5000HUA, Córdoba, Argentina.
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6
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Tsybulskaya I, Kulak T, Kalinichenko E, Baranovsky A, Bogushevich S, Golubeva M, Kuzmitsky B. Phospholipid derivatives of cladribine and fludarabine: synthesis and biological properties. Bioorg Med Chem 2015; 23:3287-96. [PMID: 25960323 DOI: 10.1016/j.bmc.2015.04.059] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 04/15/2015] [Accepted: 04/18/2015] [Indexed: 11/18/2022]
Abstract
Phospholipid derivatives of anticancer nucleosides cladribine and fludarabine (F-ara-A) bearing 1,2- and 1,3-diacylglycerol moieties have been prepared by the H-phosphonate approach using 1,1,3,3-tetraisopropyldisiloxane-1,3-diyl protecting group for cladribine and a combination of tert-butyldimethylsilyl and levulinyl protecting groups for 2-fluoroadenine nucleosides. The synthesized conjugates exhibited lower in vitro antiproliferative activity against human tumor cell lines in comparison with the same concentrations of the parent cladribine and fludarabine phosphate. In the course of biokinetic study, it was found that intragastric administration of phospholipid F-ara-A derivatives to Wistar rats and ICR outbred male mice led to a slow release of F-ara-A into the bloodstream, a smooth increase in nucleoside concentration, and prolonged serum circulation of liberated nucleoside. The oral bioavailability of F-ara-A from 1,2-dimyristoylglycerophosphate derivative 29 was similar to its oral bioavailability from fludarabine phosphate.
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Affiliation(s)
- Ilona Tsybulskaya
- Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus, BY-220141 Minsk, Belarus.
| | - Tamara Kulak
- Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus, BY-220141 Minsk, Belarus
| | - Elena Kalinichenko
- Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus, BY-220141 Minsk, Belarus
| | - Alexander Baranovsky
- Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus, BY-220141 Minsk, Belarus
| | - Svetlana Bogushevich
- Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus, BY-220141 Minsk, Belarus
| | - Marina Golubeva
- Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus, BY-220141 Minsk, Belarus
| | - Boleslav Kuzmitsky
- Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus, BY-220141 Minsk, Belarus
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7
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Peptidophospholipids: synthesis, phospholipase A2 catalyzed hydrolysis, and application to development of phospholipid prodrugs. Chem Phys Lipids 2014; 183:110-6. [PMID: 24905766 DOI: 10.1016/j.chemphyslip.2014.06.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 05/29/2014] [Accepted: 06/01/2014] [Indexed: 12/16/2022]
Abstract
New phospholipid analogues incorporating sn-2-peptide substituents have been prepared to probe the fundamental structural requirements for phospholipase A2 catalyzed hydrolysis of PLA2-directed synthetic substrates. Two structurally different antiviral oligopeptides with C-terminal glycine were introduced separately at the sn-2-carboxylic ester position of phospholipids to assess the role of the α-methylene group adjacent to the ester carbonyl in allowing hydrolytic cleavage by the enzyme. The oligopeptide-carrying phospholipid derivatives were readily incorporated into mixed micelles consisting of natural phospholipid (dipalmitoyl phosphatidylcholine, DPPC) and Triton X-100 as surfactant. Hydrolytic cleavage of the synthetic peptidophospholipids by the phospholipase A2 occurred slower, but within the same order of magnitude as the natural substrate alone. The results provide useful information toward better understanding the mechanism of action of the enzyme, and to improve the design and synthesis of phospholipid prodrugs targeted at secretory PLA2 enzymes.
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8
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Wu H, Yu L, Tong Y, Ge A, Yau S, Osawa M, Ye S. Enzyme-catalyzed hydrolysis of the supported phospholipid bilayers studied by atomic force microscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:642-51. [DOI: 10.1016/j.bbamem.2012.09.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 09/06/2012] [Accepted: 09/07/2012] [Indexed: 01/17/2023]
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9
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Volwerk J, Dedieu A, Verheij H, Dijkman R, de Haas G. Hydrolysis of monomeric substrates by porcine pancreatic (pro)phospholipase A2
. The use of a spectrophotometric assay. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/recl.19790980414] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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10
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Gudmand M, Rocha S, Hatzakis NS, Peneva K, Müllen K, Stamou D, Uji-I H, Hofkens J, Bjørnholm T, Heimburg T. Influence of lipid heterogeneity and phase behavior on phospholipase A2 action at the single molecule level. Biophys J 2010; 98:1873-82. [PMID: 20441751 PMCID: PMC2862199 DOI: 10.1016/j.bpj.2010.01.035] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Revised: 01/14/2010] [Accepted: 01/15/2010] [Indexed: 10/19/2022] Open
Abstract
We monitored the action of phospholipase A(2) (PLA(2)) on L- and D-dipalmitoyl-phosphatidylcholine (DPPC) Langmuir monolayers by mounting a Langmuir-trough on a wide-field fluorescence microscope with single molecule sensitivity. This made it possible to directly visualize the activity and diffusion behavior of single PLA(2) molecules in a heterogeneous lipid environment during active hydrolysis. The experiments showed that enzyme molecules adsorbed and interacted almost exclusively with the fluid region of the DPPC monolayers. Domains of gel state L-DPPC were degraded exclusively from the gel-fluid interface where the buildup of negatively charged hydrolysis products, fatty acid salts, led to changes in the mobility of PLA(2). The mobility of individual enzymes on the monolayers was characterized by single particle tracking. Diffusion coefficients of enzymes adsorbed to the fluid interface were between 3.2 microm(2)/s on the L-DPPC and 4.9 microm(2)/s on the D-DPPC monolayers. In regions enriched with hydrolysis products, the diffusion dropped to approximately 0.2 microm(2)/s. In addition, slower normal and anomalous diffusion modes were seen at the L-DPPC gel domain boundaries where hydrolysis took place. The average residence times of the enzyme in the fluid regions of the monolayer and on the product domain were between approximately 30 and 220 ms. At the gel domains it was below the experimental time resolution, i.e., enzymes were simply reflected from the gel domains back into solution.
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Affiliation(s)
- Martin Gudmand
- Membrane Biophysics Group, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
- Nano-Science Center, University of Copenhagen, Copenhagen, Denmark
| | - Susana Rocha
- Laboratory for Photochemistry and Spectroscopy, Department of Chemistry, Catholic University of Leuven, Leuven, Belgium
| | | | - Kalina Peneva
- Max Planck Institut für Polymerforschung, Mainz, Germany
| | - Klaus Müllen
- Max Planck Institut für Polymerforschung, Mainz, Germany
| | - Dimitrios Stamou
- Nano-Science Center, University of Copenhagen, Copenhagen, Denmark
| | - Hiroshi Uji-I
- Laboratory for Photochemistry and Spectroscopy, Department of Chemistry, Catholic University of Leuven, Leuven, Belgium
| | - Johan Hofkens
- Laboratory for Photochemistry and Spectroscopy, Department of Chemistry, Catholic University of Leuven, Leuven, Belgium
| | - Thomas Bjørnholm
- Nano-Science Center, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Heimburg
- Membrane Biophysics Group, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
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11
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Pedersen PJ, Adolph SK, Subramanian AK, Arouri A, Andresen TL, Mouritsen OG, Madsen R, Madsen MW, Peters GH, Clausen MH. Liposomal Formulation of Retinoids Designed for Enzyme Triggered Release. J Med Chem 2010; 53:3782-92. [DOI: 10.1021/jm100190c] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Palle J. Pedersen
- Department of Chemistry, Technical University of Denmark, Kemitorvet, Building 201 and 207, DK-2800 Kgs. Lyngby, Denmark
| | - Sidsel K. Adolph
- LiPlasome Pharma A/S, Technical University of Denmark, Diplomvej 378, DK-2800 Kgs. Lyngby, Denmark
| | - Arun K. Subramanian
- Department of Chemistry, Technical University of Denmark, Kemitorvet, Building 201 and 207, DK-2800 Kgs. Lyngby, Denmark
| | - Ahmad Arouri
- Department of Physics and Chemistry, MEMPHYS−Center for Biomembrane Physics, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Thomas L. Andresen
- Department of Micro- and Nanotechnology, Technical University of Denmark, DK-4000 Roskilde, Denmark
| | - Ole G. Mouritsen
- Department of Physics and Chemistry, MEMPHYS−Center for Biomembrane Physics, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Robert Madsen
- Department of Chemistry, Technical University of Denmark, Kemitorvet, Building 201 and 207, DK-2800 Kgs. Lyngby, Denmark
| | - Mogens W. Madsen
- LiPlasome Pharma A/S, Technical University of Denmark, Diplomvej 378, DK-2800 Kgs. Lyngby, Denmark
| | - Günther H. Peters
- Department of Chemistry, Technical University of Denmark, Kemitorvet, Building 201 and 207, DK-2800 Kgs. Lyngby, Denmark
| | - Mads H. Clausen
- Department of Chemistry, Technical University of Denmark, Kemitorvet, Building 201 and 207, DK-2800 Kgs. Lyngby, Denmark
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12
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Savin GA. [Synthesis of acetal and phosphocyclic methriolipids]. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2008; 34:822-6. [PMID: 19088757 DOI: 10.1134/s1068162008060149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The first representatives of acetal and phosphocyclic lipids based on methriol (2-hydroxymethyl-2-methyl-1,3-propanediol) were synthesized. The interaction of the starting triol with higher aldehydes gave the corresponding alkylidene compounds, which were subsequently phosphorylated by derivatives of phosphorous acid. The intermediate amidophosphites were treated without isolation with iodobenzene, sulfur, or selenium to give phosphoacetals and their thio- and selenoanalogues, which are acetal phospholipids. Methriol bicyclophosphite was also used in the lipid synthesis. It was acylated with palmitoyl chloride at one of the bicyclic oxygen atoms. Alcoholysis of acyl polyol chlorophosphite resulted in a phospholipid, which was oxidized with sulfur to give thionphosphate.
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Affiliation(s)
- G A Savin
- Volgograd State Pedagogical University, pr. Lenina 27, Volgograd, 400131 Russia.
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13
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Rand Doyen J, Yucer N, Lichtenberger LM, Kulmacz RJ. Phospholipid actions on PGHS-1 and -2 cyclooxygenase kinetics. Prostaglandins Other Lipid Mediat 2007; 85:134-43. [PMID: 18201917 DOI: 10.1016/j.prostaglandins.2007.12.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2007] [Revised: 11/10/2007] [Accepted: 12/03/2007] [Indexed: 10/22/2022]
Abstract
Cyclooxygenase (COX) catalysis by prostaglandin H synthase (PGHS) is a key control step for regulation of prostanoid biosynthesis. Both PGHS isoforms are integral membrane proteins and their substrate fatty acids readily partition into membranes, but the impact of phospholipids and lipid membranes on COX catalysis and the actions of COX inhibitors are not well understood. We have characterized the COX kinetics and ibuprofen inhibition of the purified PGHS isoforms in the presence of phosphatidylcholine (PC) with varying acyl chain structure and physical state. PC was found to directly inhibit COX activity, with non-competitive inhibition by PC monomers binding away from the COX active site and competitive inhibition by micellar/bilayer forms of PC due to sequestration of the arachidonate substrate. Competitive inhibition by native membranes was observed in a comparison of COX kinetics in sheep seminal vesicle microsomes before and after solubilization of PGHS-1. PC liposomes significantly increase the inhibitory potency of ibuprofen against both PGHS isoforms without changing the reversible character of ibuprofen action or requiring binding of PGHS to the liposomes. These results suggest a useful conceptual framework for analyzing the complex interactions among the PGHS proteins, substrates, inhibitors and phospholipid.
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Affiliation(s)
- J Rand Doyen
- Department of Integrative Biology & Pharmacology, University of Texas Health Science Center at Houston, Houston, TX 77030, United States
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14
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Brake JM, Abbott NL. Coupling of the orientations of thermotropic liquid crystals to protein binding events at lipid-decorated interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:8497-507. [PMID: 17595119 DOI: 10.1021/la0634286] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
We report a study of the interactions of proteins with monolayers of phospholipids (D/L-alpha-dipalmitoyl phosphatidylcholine and L-alpha-dilauroyl phosphatidylcholine) spontaneously assembled at an interface between an aqueous phase and a 20-microm-thick film of a nematic liquid crystal (4'-pentyl-4-cyanobiphenyl). Because the orientation of the liquid crystal is coupled to the organization of the lipids, specific interactions between phospholipase A2 and the lipids (binding and/or hydrolysis) that lead to reorganization of the lipids are optically reported (using polarized light) as dynamic orientational transitions in the liquid crystal. In contrast, nonspecific interactions between proteins such as albumin, lysozyme, and cytochrome-c and the lipid-laden interface of the liquid crystal are not reported as orientational transitions in the liquid crystals. Concurrent epifluorescence and polarized light imaging of labeled lipids and proteins at the aqueous-liquid crystal interface demonstrate that spatially patterned orientations of the liquid crystals observed during specific binding of phospholipase A2 to the interface, as well as during the subsequent hydrolysis of lipids by phospholipase A2, reflect the lateral organization (micrometer-sized domains) of the proteins and lipids, respectively, at the aqueous-liquid crystal interface.
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Affiliation(s)
- Jeffrey M Brake
- Department of Chemical Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, Wisconsin 53706, USA
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15
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Linderoth L, Peters GH, Jørgensen K, Madsen R, Andresen TL. Synthesis of sn-1 functionalized phospholipids as substrates for secretory phospholipase A2. Chem Phys Lipids 2007; 146:54-66. [PMID: 17270166 DOI: 10.1016/j.chemphyslip.2006.12.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2006] [Revised: 12/04/2006] [Accepted: 12/22/2006] [Indexed: 10/23/2022]
Abstract
Secretory phospholipase A2 (sPLA2) represents a family of small water-soluble enzymes that catalyze the hydrolysis of phospholipids in the sn-2 position liberating free fatty acids and lysophospholipids. Herein we report the synthesis of two new phospholipids (1 and 2) with bulky allyl-substituents attached to the sn-1 position of the glycerol backbone. The synthesis of phospholipids 1 and 2 is based upon the construction of a key aldehyde intermediate 3 which locks the stereochemistry in the sn-2 position of the final phospholipids. The aldehyde functionality serves as the site for insertion of the allyl-substituents by a zinc mediated allylation. Small unilamellar liposomes composed of phospholipids 1 and 2 were subjected to sPLA2 activity measurements. Our results show that only phospholipid 1 is hydrolyzed by the enzyme. Molecular dynamics simulations revealed that the lack of hydrolysis of phospholipid 2 is due to steric hindrance caused by the bulky side chain of the substrate allowing only limited access of water molecules to the active site.
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Affiliation(s)
- Lars Linderoth
- Department of Chemistry, Technical University of Denmark, Denmark
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16
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Bacha AB, Gargouri Y, Bezzine S, Mejdoub H. Purification and biochemical characterization of phospholipase A2 from dromedary pancreas. Biochim Biophys Acta Gen Subj 2006; 1760:1202-9. [PMID: 16733083 DOI: 10.1016/j.bbagen.2006.03.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2005] [Revised: 03/09/2006] [Accepted: 03/13/2006] [Indexed: 11/16/2022]
Abstract
Dromedary pancreatic PLA2 (DrPLA2) was purified from delipidated pancreases. Pure protein was obtained after heat and acidic treatment (70 degrees C; pH 3.0), precipitation by ammonium sulphate and ethanol respectively, followed by sequential column chromatographies on Sephadex G-50, MonoS Sepharose, MonoQ Sepharose and C-8 reverse phase high pressure liquid chromatography. Purified DrPLA2, which is not glycosylated protein, was found to be monomeric protein with a molecular mass of 13748.55 Da. A specific activity of 600 U/mg for purified DrPLA2 was measured at optimal conditions (pH 8.0 and 37 degrees C) in the presence of 3 mM NaTDC and 7 mM CaCl(2) using PC as substrate. The sequence of the first fourteen amino-acid residues at the N-terminal extremity of DrPLA2 was determined by automatic Edman degradation. One single sequence was obtained and shows a close similarity with all other known pancreatic secreted phospholipases A2.
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Affiliation(s)
- Abir Ben Bacha
- Laboratoire de Biochimie et de Génie Enzymatique des Lipases, ENIS route de Soukra, 3038 Sfax, Tunisia
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17
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Brake JM, Daschner MK, Abbott NL. Formation and characterization of phospholipid monolayers spontaneously assembled at interfaces between aqueous phases and thermotropic liquid crystals. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:2218-2228. [PMID: 15752009 DOI: 10.1021/la0482397] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
This paper reports an experimental investigation of the self-assembly of phospholipids (l-alpha-phosphatidylcholine-beta-oleoyl-gamma-palmitoyl (l-POPC), dipalmitoyl phosphatidylcholine (DPPC), and l-alpha-dilauroyl phosphatidylcholine (l-DLPC)) at interfaces between aqueous phases and the nematic liquid crystal (LC) 4'-pentyl-4-cyanobiphenyl. Stable planar interfaces between the aqueous phases and LCs were created by hosting the LCs within gold grids (square pores with widths of 283 microm and depths of 20 microm). At these interfaces, the presence and lateral organization of the phospholipids leads to interface-driven orientational transitions within the LC. By doping the phospholipids with a fluorescently labeled lipid (Texas Red-1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (TR-DPPE)), quantitative epifluorescence microscopy revealed the saturation coverage of phospholipid at the interface to be that of a monolayer with an areal density of approximately 49 +/- 8% relative to hydrated lipid bilayers. By adsorbing phospholipids to the aqueous-LC interface from either vesicles or mixed micelles of dodecyltrimethylammonium and phospholipid, control of the areal density of phospholipid from 42 +/- 10 to 102 +/-18% of saturation monolayer coverage was demonstrated. Fluorescence recovery after photobleaching (FRAP) experiments performed by using laser scanning confocal microscopy (LSCM) revealed the lateral mobility of fluorescently labeled DPPE in l-DLPC assembled at the interface with the liquid crystal to be (6 +/- 1) x 10(-12) m(2)/s for densely packed monolayers. Variation of the surface coverage and composition of phospholipid led to changes in lateral diffusivity between (0.2 +/- 0.1) x 10(-12) and (15 +/- 2) x 10(-12) m(2)/s. We also observed the phospholipid-laden interface to be compartmentalized by the gold grid, thus allowing for the creation of patterned arrays of phospholipids at the LC-aqueous interface.
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Affiliation(s)
- Jeffrey M Brake
- Department of Chemical Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706, USA
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18
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Zhai X, Bartel M, Brezesinski G, Rattay B, Möhwald H, Li J. Small angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC) studies of amide phospholipids. Chem Phys Lipids 2004; 133:79-88. [PMID: 15589228 DOI: 10.1016/j.chemphyslip.2004.09.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2004] [Revised: 09/06/2004] [Accepted: 09/08/2004] [Indexed: 11/18/2022]
Abstract
Varying chemically the structure of phospholipids in the region between hydrophobic and hydrophilic segments is expected to have a strong influence on the interaction with water and the phase behavior. This is studied in this work with the motivation to investigate these lipids as potential inhibitors of phospholipase A2. Thus the amide phospholipids L-ether-amide-PC (1-O-hexadecyl-2-N-palmitoyl-2-amino-2-deoxy-sn-glycero-3-phosphocholine), L-ester-amide-PC (1-palmitoyl-2-N-palmitoyl-2-amino-2-deoxy-sn-glycero-3-phosphocholine) and L-ether-amide-PE (1-O-hexadecyl-2-N-palmitoyl-2-deoxy-sn-glycero-3-phosphoethanolamine) have been synthesized and characterized. The phase behavior and thermal transitions in buffer dispersions are examined by a combination of high-sensitivity differential scanning calorimetry (DSC) and small angle X-ray scattering (SAXS) experiments between 10 and 80 degrees C at pH 8.9. The onset temperatures determined from DSC measurements agree well with the starting temperatures of changes in the repeat distance obtained by SAXS measurements. The phases observed are lamellar both below and above the main phase transition. The phase transition temperatures and enthalpies depend strongly on the substitutions in sn-1 position and head group structure. The lamellar repeat distance in gel and liquid-crystalline phases increases with increasing temperature for L-ester-amide-PC and L-ether-amide-PC, whereas the temperature dependence is opposite for the L-ether-amide-PE. The observed behavior is discussed and compared with that of DPPC and DPPE, indicating the strong dependence of hydration and phase behavior on head group structure.
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Affiliation(s)
- Xiuhong Zhai
- International Joint Lab, Key Lab of Colloid and Interface Science, The Center for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Zhong Guan Cun, Beijing 100080, China
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19
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Synthesis of first phospholipids from 2,2,6,6-tetrakis(hydroxymethyl)cyclohexanol. RUSSIAN JOURNAL OF ORGANIC CHEMISTRY 2004. [DOI: 10.1007/s11178-005-0021-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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20
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Brake JM, Daschner MK, Luk YY, Abbott NL. Biomolecular interactions at phospholipid-decorated surfaces of liquid crystals. Science 2004; 302:2094-7. [PMID: 14684814 DOI: 10.1126/science.1091749] [Citation(s) in RCA: 379] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The spontaneous assembly of phospholipids at planar interfaces between thermotropic liquid crystals and aqueous phases gives rise to patterned orientations of the liquid crystals that reflect the spatial and temporal organization of the phospholipids. Strong and weak specific-binding events involving proteins at these interfaces drive the reorganization of the phospholipids and trigger orientational transitions in the liquid crystals. Because these interfaces are fluid, processes involving the lateral organization of proteins (such as the formation of protein- and phospholipid-rich domains) are also readily imaged by the orientational response of the liquid crystal, as are stereospecific enzymatic events. These results provide principles for label-free monitoring of aqueous streams for molecular and biomolecular species without the need for complex instrumentation.
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Affiliation(s)
- Jeffrey M Brake
- Department of Chemical and Biological Engineering, University of Wisconsin, Madison, 1415 Engineering Drive, Madison, WI 53706-1607, USA
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21
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Monolayer technique for the study of the hydrolysis of dilaurin isomers biocatalysed by different lipases. Colloids Surf B Biointerfaces 2004. [DOI: 10.1016/j.colsurfb.2003.08.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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22
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Zhai X, He Q, Li J, Brezesinski G, Möhwald H. Self-Organization of an L-Ether-amide Phospholipid in Large Two-Dimensional Chiral Crystals. Chemphyschem 2003; 4:1355-8. [PMID: 14714387 DOI: 10.1002/cphc.200300912] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Xiuhong Zhai
- International Joint Lab, Key Lab of Colloid and Interface Science, Center for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Zhong Guan Cun, Beijing 100080, China
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23
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Enzymatic Reactions at Interfaces. ACTA ACUST UNITED AC 2002. [DOI: 10.1016/s1383-7303(02)80006-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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24
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Grainger D, Reichert A, Ringsdorf H, Salesse C. An enzyme caught in action: Direct imaging of hydrolytic function and domain formation of phospholipase A2in phosphatidylcholine monolayers. FEBS Lett 2001. [DOI: 10.1016/0014-5793(89)80892-0] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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25
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Berg OG, Gelb MH, Tsai MD, Jain MK. Interfacial enzymology: the secreted phospholipase A(2)-paradigm. Chem Rev 2001; 101:2613-54. [PMID: 11749391 DOI: 10.1021/cr990139w] [Citation(s) in RCA: 266] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- O G Berg
- Evolutionary Biology Center, Uppsala University, Uppsala, Sweden
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26
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Ishikawa S. [Software development for calculation of molecular surface area and its application to hydrophobic interaction]. YAKUGAKU ZASSHI 2001; 121:47-63. [PMID: 11201162 DOI: 10.1248/yakushi.121.47] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A novel method of calculating the water-accessible molecular surface area from the number of points generated on the molecular surface was developed. This method yielded a molecular surface area with high accuracy and speed. The molecular surface area of lecithin shows an excellent linear correlation with the logarithm of the critical micelle concentration for many lecithins having different acyl chains. The solution structure of oxyphenonium bromide estimated from the molecular surface area approach was close to that obtained from NMR. Furthermore, the change of molecular surface area, delta S(HG), with docking of host and guest was defined and its calculation method was developed. Because both the host and the guest generally consist of hydrophilic and hydrophobic atomic groups, delta S(HG) was divided into such four terms as delta Soo(HG), delta Sow(HG), delta Swo(HG), and delta Sww(HG). For instance, delta Soo(HG) is the decrease in surface area with contact between the hydrophobic surfaces of the host and the guest. When the guest molecule was moved along the symmetry axis of cyclodextrin (CyD), the structure of a complex having the maximum value of delta Soo(HG) corresponds with the crystal structure. The solution structures of several inclusion systems were predicted by this method. For various systems including alpha-CyD, beta-CyD, gamma-CyD, and aromatic and aliphatic guests, the maximum values of delta Soo(HG) showed a good correlation with the logarithms of the binding constants. This relationship will be used for the prediction of the binding constants for CyD and other host-guest systems.
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Affiliation(s)
- S Ishikawa
- Kyoto Pharmaceutical University, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan
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27
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Abstract
The physico-chemical properties of short-chain phosphatidylcholine are reviewed to the extent that its biological activity as a mild detergent can be rationalized. Long-chain diacylphosphatidylcholines are typical membrane phospholipids that form preferentially smectic lamellar phases (bilayers) when dispersed in water. In contrast, the preferred phase of the short-chain analogues dispersed in excess water is the micellar phase. The preferred conformation and the dynamics of short-chain phosphatidylcholines in the monomeric and micellar state present in H(2)O are discussed. The motionally averaged conformation of short-chain phosphatidylcholines is then compared to the single-crystal structures of membrane lipids. The main conclusion emerging is that in terms of preferred conformation and motional averaging short-chain phosphatidylcholines closely resemble their long-chain analogues. The dispersing power of short-chain phospholipids is emphasized in the second part of the review. Evidence is presented to show that this class of compounds is superior to most other detergents used in the solubilization of membrane proteins and the reconstitution of the solubilized proteins to artificial membrane systems (proteoliposomes). The prominent feature of the solubilization/reconstitution of integral membrane proteins by short-chain PC is the retention of the native protein structure and hence the protein function. Due to their special detergent-like properties, short-chain PC lend themselves very well not only to membrane solubilization but also to the purification of integral membrane proteins. The retention of the native protein structure in the solubilized state, i.e. in mixed micelles consisting of the integral membrane protein, intrinsic membrane lipids and short-chain PC, is rationalized. It is hypothesized that short-chain PC interacts primarily with the lipid bilayer of a membrane and very little if at all with the membrane proteins. In this way, the membrane protein remains associated with its preferred intrinsic membrane lipids and retains its native structure and its function.
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Affiliation(s)
- H Hauser
- Institute of Biochemistry, Swiss Federal Institute of Technology, ETH Centre, Universitätsstrasse 16, CH-8092, Zurich, Switzerland.
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28
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Bartel M, Rattay B, Nuhn P. Synthesis of enantiomerically pure, sn-1 modified sn-2-deoxy-2-amido-glycero-3-phospholipids. Chem Phys Lipids 2000; 107:121-9. [PMID: 10974236 DOI: 10.1016/s0009-3084(00)00156-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The synthesis of two types of enantiomerically pure sn-2-deoxy-2-amido-glycero-phospholipids differing in the connection of the alkyl chain at the sn-1-position is described. Both types of lipids were prepared from L-serine-methylester as the chiral starting material.
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Affiliation(s)
- M Bartel
- Institut für Pharmazeutische Chemie, Martin-Luther-Universität Halle-Wittenberg, Wittenberg, Germany
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29
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30
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Boucrot P, Bobin-Dubigeon C, Elkihel L, Letourneux Y, Jugé M, Gandemer G, Petit JY. Secreted and intracellular phospholipases A2 inhibition by 1-decyl 2-octyl-glycerophosphocholine in rat peritoneal macrophages. Fundam Clin Pharmacol 1998; 12:433-41. [PMID: 9711466 DOI: 10.1111/j.1472-8206.1998.tb00968.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Compounds able to inhibit phospholipases A2 can be considered as potential anti-inflammatory drugs. In this respect, the inhibitory effect of the phospholipid analogue 1-decyl 2-octyl-rac-glycero-3-phosphocholine (decyloctyl-GPC) added to the culture medium of rat peritoneal macrophages stimulated with ionophore A23187 was determined. (a) The substrate of phospholipase A2 1-octadecanoyl 2-[14C]eicosatetraenoyl-sn-glycero-3-phosphocholine ([14C]20:4-GPC) was added to the culture medium. In macrophages + extracellular fluids, its hydrolysis at the 2-position, produced [14C]non-phosphorous lipids which reached 12% of the dose at 0.14 microM, 73% at 0.9 and > 90% at 1.6 microM; in experiments where macrophages and extracellular fluids were analyzed separately, decyloctyl-GPC initially added at 4 microM, significantly inhibited the release of [14C]fatty acids and the eicosanoid synthesis, demonstrating its ability to inhibit secreted and/or intracellular phospholipases A2. (b) Extracellular fluids were separated from the macrophages and incubated with [14C]20:4-GPC: 48% of the dose was hydrolyzed by extracellular fluid-associated secreted phospholipase A2 and decyloctyl-GPC at 3 microM, reduced this hydrolysis by 50%. (c) [3H]arachidonic acid ([3H]20:4) was added to the culture medium and was esterified in the macrophage membrane phospholipids. Activation of intracellular phospholipase A2 induced the release of [3H] fatty acids and eicosanoid synthesis. These releases were inhibited by 50% with decyloctyl-GPC added at 4 microM. (d) [3H]20:4 and [14C]20:4-GPC were added to the culture medium of the macrophages. [3H] and [14C] fatty acids and eicosanoids were released in macrophages or extracellular fluids. They were significantly reduced by the phospholipid analogue added at 4 microM. It is concluded that secreted and intracellular phospholipases A2 were both inhibited by decyloctyl-GPC which extensively reduced the 20:4 release from exogenous and membrane phospholipids and therefore eicosanoid synthesis.
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Affiliation(s)
- P Boucrot
- Laboratoire d'étude des interactions des molécules alimentaires, INRA, Nantes, France
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31
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Fuji M, Fumihiko Watanabe,, Fujii Y, Hashizume H, Okuno T, Shirahase K, Teshirogi I, Ohtani M. A Stereoselective and Highly Practical Synthesis of Cytosolic Phospholipase A2 Substrate, 2-S-Arachidonoyl-1-O-hexadecyl-sn-2-thioglycero-3-O-phosphocholine. J Org Chem 1997. [DOI: 10.1021/jo970882t] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Masahiro Fuji
- Shionogi Research Laboratories, Shionogi & Co., Ltd., Sagisu, Fukushima-ku, Osaka 553, Japan
| | - Fumihiko Watanabe,
- Shionogi Research Laboratories, Shionogi & Co., Ltd., Sagisu, Fukushima-ku, Osaka 553, Japan
| | - Yasuhiko Fujii
- Shionogi Research Laboratories, Shionogi & Co., Ltd., Sagisu, Fukushima-ku, Osaka 553, Japan
| | - Hiroshi Hashizume
- Shionogi Research Laboratories, Shionogi & Co., Ltd., Sagisu, Fukushima-ku, Osaka 553, Japan
| | - Takayuki Okuno
- Shionogi Research Laboratories, Shionogi & Co., Ltd., Sagisu, Fukushima-ku, Osaka 553, Japan
| | - Kazuhiro Shirahase
- Shionogi Research Laboratories, Shionogi & Co., Ltd., Sagisu, Fukushima-ku, Osaka 553, Japan
| | - Isao Teshirogi
- Shionogi Research Laboratories, Shionogi & Co., Ltd., Sagisu, Fukushima-ku, Osaka 553, Japan
| | - Mitsuaki Ohtani
- Shionogi Research Laboratories, Shionogi & Co., Ltd., Sagisu, Fukushima-ku, Osaka 553, Japan
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32
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Clary L, Verderone G, Santaella C, Vierling P. Membrane permeability and stability of liposomes made from highly fluorinated double-chain phosphocholines derived from diaminopropanol, serine or ethanolamine. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1328:55-64. [PMID: 9298945 DOI: 10.1016/s0005-2736(97)00076-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The release of encapsulated carboxyfluorescein (CF) from liposomes made from various fluorinated amido-connected double-chain phosphocholines and their membrane permeability have been investigated at 37 degrees C in buffer and in human serum. These fluorinated membranes and liposomes display lower permeability coefficients and are able to retain more efficiently encapsulated CF than any of their respective conventional counterparts. Several of these liposomes are as effective as the first generation of liposomes based on fluorinated phosphatidylcholines, indicating that the chemical junction (ester/amide) and nature of the unit (glycerol, diaminopropanol, serine, ethanolamine) connecting the hydrophobic chains to the phosphocholine polar head have no significant effect on permeability and CF release. Our results show further that a fluorinated intramembrane layer reduces significantly the permeability of membranes in a liquid-crystalline state, protects the liposomes from the destabilizing effects of serum, and even increases their stability (in terms of dye retention) in serum when the membranes are in the gel state.
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Affiliation(s)
- L Clary
- Laboratoire de Chimie Bioorganique, UPRESA 6001 CNRS, Faculté des Sciences, Université de Nice-Sophia Antipolis, Nice, France
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33
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Bourass J, Boucrot P, Letourneux Y, Gandemer G, Petit JY. Uptake of the phospholipase A2 inhibitor 1-dodecyl 2-[1-14C] octanamido-sn-2-deoxy glycero-3-phosphocholine by peritoneal macrophages. JOURNAL OF ENZYME INHIBITION 1997; 12:227-40. [PMID: 9314117 DOI: 10.3109/14756369709029316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The [14C] phospholipid analogue 1-dodecyl-2-[1-14C] octanamido-sn-2-deoxy glycero-3-phosphocholine was synthetized. With 2 short fatty chains linked by alkyl and amido bonds to positions 1 and 2 of the glycerophosphate backbone, it was an inhibitor of phospholipase A2 in ionophore A23187-stimulated macrophages. Its uptake by rat peritoneal macrophages and its resistance towards phospholipases A2 were determined at nanomolar or micromolar concentrations in the culture medium. A control substrate for phospholipases A2 activity was established with the lecithin 1-octadecanoyl 2-[3H] eicosatetraenoyl-sn-glycero-3-phosphocholine ([3H] 20:4-GPC), a source of [3H] arachidonic acid after cleavage at position 2. Non-stimulated- or ionophore A23187-stimulated macrophages incorporated extensively the [14C] phospholipid analogue added at 30-4000 nM. At 4000 nM which induced 50% inhibition of the phospholipase, 40% of the dose was found associated with the [14C] phospholipids of 2 x 10(6) stimulated macrophages after 120 min incubation, while only low amounts of [14C] non-phosphorous lipids were detected. It is concluded that the [14C] phospholipid analogue was readily taken up by the macrophages with limited hydrolysis.
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Affiliation(s)
- J Bourass
- Laboratoire de synthèse et d'étude des substances naturelles à activité biologique, pôle sciences, La Rochelle, France
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34
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Polymorphic phase behavior of fluorocarbon double-chain phosphocholines derived from diaminopropanol, serine and ethanolamine and long-term shelf stability of their liposomes. Chem Phys Lipids 1997. [DOI: 10.1016/s0009-3084(97)02657-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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35
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36
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Lin G, Hsiao-Chien Liu, Yi-Chin Tsai. Atropisomeric carbamoyl type inhibitors of pancreatic cholesterol esterase. Bioorg Med Chem Lett 1996. [DOI: 10.1016/0960-894x(95)00549-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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37
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Clary L, Santaella C, Vierling P. Synthesis and evaluation of the in vivo tolerance of amido fiuorocarbon/fluorocarbon and fluorocarbon/hydrocarbon double-chain phosphocholines deriving from diaminopropanols and serine. Tetrahedron 1995. [DOI: 10.1016/0040-4020(95)00837-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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38
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De Haas GH, Dijkman R, Boots JW, Verheij HM. Competitive inhibition of lipolytic enzymes. XI. Estimation of the interfacial dissociation constants of porcine pancreatic phospholipase A2 for substrate and inhibitor in the absence of detergents. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1257:87-95. [PMID: 7619862 DOI: 10.1016/0005-2760(95)00034-a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Based on the strong inhibitory properties of (R)-2-decanoylamino-octanol-1-phosphocholine and its phosphoglycol analogue for porcine pancreatic phospholipase A2, the corresponding 2-decanoyloxy derivatives have been synthesised in both enantiomeric forms and their substrate properties for the enzyme were analysed. The high aqueous solubility in the absence of detergents, combined with low critical micelle concentrations of both the amide- and ester phospholipids allowed the estimation of the interfacial dissociation constants of the enzyme-substrate and enzyme-inhibitor complexes by kinetic and direct binding techniques.
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Affiliation(s)
- G H De Haas
- Department of Enzymology and Protein Engineering, C.B.L.E., Utrecht, The Netherlands
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39
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Glaser KB. Regulation of phospholipase A2 enzymes: selective inhibitors and their pharmacological potential. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 1995; 32:31-66. [PMID: 7748798 DOI: 10.1016/s1054-3589(08)61011-x] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The area of PLA2 research has grown immensely over the past 20 years. There is a better understanding of the kinetics, or factors that affect the kinetics, of the different forms of PLA2. New forms of PLA2 are being discovered, such as the cPLA2, which fit the role of an intracellularly regulated enzyme. Multiple forms of PLA2 tend to complicate the elucidation of the cellular mechanisms that regulate AA release and the subsequent eicosanoid production. Because of the factors that affect PLA2 kinetics and the unknown nature of the PLA2 that regulates AA release (there may be more than one), it has been difficult to design or isolate specific inhibitors. This review discussed selected classes of inhibitors because these have generated the most intense research in the field. There is a multitude of structurally diverse compounds reported in the literature that have been reported to be inhibitors of PLA2 in vitro and some have been reported to have anti-inflammatory activity (Wilkerson, 1990; Connolly and Robinson, 1993a). It is clear from a brief survey of the literature that the bulk of PLA2 inhibitors have topical anti-inflammatory activity. This may be due to the nature of these inhibitors: because they are hydrophobic they may be more readily absorbed in the skin whereas when given orally they may not be absorbed. To data, manoalide has been clinically evaluated in man and a new Bristol-Myers Squibb retenoid derivative may enter clinical trials for psoriasis (BMS-181162 (XVI)); however, there are no PLA2 inhibitors on the market or significantly advanced in clinical development (Table III). This indicates the lack of understanding of this enzyme for the development of relevant inhibitors, which is related to the lack of understanding of the relevant PLA2 that regulates AA release and eicosanoid biosynthesis. The concept of regulation of eicosanoid biosynthesis by PLA2 inhibition and decreased AA availability still remains a viable therapeutic approach for the treatment of inflammatory diseases. The proof of this concept has not been obtained because of the complex nature of PLA2 and the multiple forms of PLA2 in the cell. Clinical results with cyclooxygenase inhibitors and recent clinical results with inhibitor of 5-lipoxygenase demonstrate that if inhibition of PLA2 results in reduction in both lipid mediators, a good anti-inflammatory compound should result. The added advantage of PLA2 inhibitors would be the reduction of PAF levels; however, the clinical results with potent and specific PAF antagonists has been less encouraging about the potential benefits of reduction in PAF levels.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- K B Glaser
- Wyeth-Ayerst Research/Princeton, New Jersey 08543, USA
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Petit JY, Boucrot P, Lang F, Welin L. Comparison of macrophage phospholipid radiolabelling methods for measuring phospholipase A2 inhibition. ARCHIVES INTERNATIONALES DE PHYSIOLOGIE, DE BIOCHIMIE ET DE BIOPHYSIQUE 1994; 102:271-5. [PMID: 7849275 DOI: 10.3109/13813459409003943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Rat peritoneal macrophages activated by ionophore A 23187, were labelled after introduction in the culture medium of 1-0-stearoyl 2-0-[3H] arachidonylglycero-3-phosphocholine (as unique source of tritiated arachidonic acid), or [3H] arachidonic acid which was esterified by cells in phospholipids and triglycerides or remained non esterified. With either cell-labelling method, stimulated macrophages produced tritiated nonesterified fatty acids and eicosanoids which were isolated from cell and medium lipids. When introduced into the culture medium at 1, 5 or 10 microM, the membrane phospholipid analogue 1,2 di-O-hexadecylglycerophosphocholine (dihexadecyl-GPC), but not the lysolecithin analogue 1-0-octadecyl 2-0-methylglycero phosphocholine, lowered phospholipase A2 activity with either labelling method. Dihexadecyl-GPC had an inhibitory effect on the release of arachidonic acid and eicosanoids. Moreover, this effect, as measured by tritiated nonesterified fatty acid formation, was greater in activated cells labelled with tritiated phospholipid (IC50 6 microM) than with [3H] arachidonic acid (IC50 60 microM). This is attributable to the inhibitory effect of dihexadecyl-GPC on endogenous phospholipase A2 and the endogenous enzyme excreted together with lysosomes into the medium. It may be concluded that radioactive phospholipid labelling is a sensitive method for measuring phospholipase A2 activity and assessing the effects of potential phospholipase inhibitors.
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Affiliation(s)
- J Y Petit
- Laboratoire de Pharmacologie et Pharmacocinétique, Faculté de Pharmacie, INRA, Nantes, France
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Katsumura S, Iwama S, Matsuda T, Tani T, Fuji S, Ikeda K. Synthesis of oxazolidinone phospholipid analogue as a new inhibitor of phospholipase A2. Bioorg Med Chem Lett 1993. [DOI: 10.1016/s0960-894x(01)80746-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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42
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Chen YS, King RG, Rook TJ, Brennecke SP. Effect of the choline acetyltransferase inhibitor (2-benzoylethyl)-trimethylammonium iodide (BETA) on human placental prostaglandin release and phospholipase A2 activity. Placenta 1993; 14:627-40. [PMID: 8153085 DOI: 10.1016/s0143-4004(05)80380-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We investigated the effect of an inhibitor of acetylcholine (ACh) synthesis, (2-benzoylethyl)trimethylammonium iodide (BETA), on prostaglandin (PG)E2 and PGF2 alpha release from incubated placental explants in the presence or absence of ACh or arachidonic acid (AA). BETA alone (100 microM) significantly reduced both PGE2 and PGF2 alpha release. However, this inhibitory effect of BETA was not reversed in the presence of ACh (10 microM to 1 mM). The addition of AA (10 to 100 microM) increased both PGE2 and PGF2 alpha release, and simultaneously overcame the inhibition of PGE2 but not PGF2 alpha release by BETA. These results are compatible with the hypothesis that BETA may be inhibiting the phospholipase A2 (PLA2) step rather than prostaglandin H synthase (PGHS) step in the enzymatic pathway of PG generation. This hypothesis was supported by evidence showing a lack of effect of BETA (10 and 100 microM) on ovine placental microsome PGHS activity. Moreover, human placental homogenate PLA2 activity was reversibly inhibited by BETA (100 microM). In the presence of BETA (100 microM), addition of exogenous ACh (100 microM) had no significant effect on placental PLA2 activity. These results indicate that the inhibitory effect of BETA on placental PG release was unlikely to be via an action on ACh synthesis, but rather via a reversible effect on PLA2 activity.
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Affiliation(s)
- Y S Chen
- Monash Perinatal Unit, Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
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43
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Lin G, Liu SH, Wu FC, Jen WJ. Novel Acyl Donors for Enzyme-Catalyzed Transacylation Reactions. SYNTHETIC COMMUN 1993. [DOI: 10.1080/00397919308018607] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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44
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Kido H, Sakai K, Kishino Y, Tashiro M. Pulmonary surfactant is a potential endogenous inhibitor of proteolytic activation of Sendai virus and influenza A virus. FEBS Lett 1993; 322:115-9. [PMID: 8387030 DOI: 10.1016/0014-5793(93)81549-f] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The pathogenicities of influenza viruses and paramyxoviruses have been proposed to be primarily determined by a host cell protease(s) that activates viral infectivity by proteolytic cleavage of the envelope glycoproteins. We recently isolated a trypsin-type endoprotease, named tryptase Clara, from rat bronchial and bronchiolar epithelial Clara cells, which is secreted into the airway lumen and activates Sendai virus and influenza A virus proteolytically. We report here that surfactant in the bronchial fluid inhibited tryptase Clara specifically, having a Ki value of 0.13 microM, and inhibited the proteolytic activations by tryptase Clara in vitro and in organ cultures of rat lung. Intranasal infection of rats with Sendai virus was shown to stimulate secretion of tryptase Clara without changing the amount of surfactant in the bronchial lumen, resulting in a preferable condition for proteolytic viral activation and multiplication.
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Affiliation(s)
- H Kido
- Division of Enzyme Chemistry, University of Tokushima, Japan
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45
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de Haas GH, Dijkman R, Lugtigheid RB, Dekker N, Van den Berg L, Egmond MR, Verheij HM. Competitive inhibition of lipolytic enzymes. IX. A comparative study on the inhibition of pancreatic phospholipases A2 from different sources by (R)-2-acylamino phospholipid analogues. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1167:281-8. [PMID: 8481389 DOI: 10.1016/0005-2760(93)90230-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The inhibitory power (Z) of a number of (R)-1-alkyl-2-acylamino phospholipid analogues was determined for three mammalian phospholipases A2 from pig, ox and horse pancreas. All three enzymes display a clear preference for anionic (phosphoglycol) inhibitors over the zwitterionic (phosphocholine) derivatives; this effect is most pronounced for the bovine enzyme. Upon variation of the 1-alkyl chain length, the bovine and equine phospholipases, like the porcine enzyme in previous studies, show an optimum in Z for a six-carbon alkyl group. The introduction of a double bond in the 2-acylamino group generally improves the inhibitory power as compared with a fully saturated acyl chain. For the horse enzyme, the presence of an (R)-2-undecenoylamino group in the phosphocholine- and phosphoglycol-containing inhibitors resulted in affinities which are nearly 4 and 5 orders of magnitude higher, respectively, than for the substrate molecule. Direct determination of the dissociation constant Ki* of several inhibitors incorporated in a host lipid/water interface of non-inhibitory n-octadecenylphosphocholine micelles, was performed by ultraviolet difference spectroscopy. The progressive binding of a single inhibitor molecule into the active site of the three enzymes was followed quantitatively by an increasing tyrosine perturbation. With moderately strong competitive inhibitors (Z values ranging from about 50 to 10,000), quantitative values for Ki* were obtained. Extrapolation of the experimentally found linear relationship between Z and 1/Ki* yields predicted Ki* numbers for the much stronger inhibitors with Z values between 10,000 and 100,000.
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Affiliation(s)
- G H de Haas
- Department of Enzymology and Protein Engineering, C.B.L.E., Utrecht, The Netherlands
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46
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Bhat MK, Mueller-Harvey I, Sumner IG, Goodenough PW. Simplified methods for the synthesis of 2-hexadecanoylthio-1-ethylphosphorylcholine and for the determination of phospholipase A2 activity. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1166:244-50. [PMID: 8443243 DOI: 10.1016/0005-2760(93)90104-h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A simple and straight forward method was developed for the synthesis of 2-hexadecanoylthio-1-ethyl phosphorylcholine (HEPC). The new procedure, which used p-toulenesulfonate instead of 2-bromoethyl phosphorylcholine, not only reduced the reaction time but also allowed the reaction to proceed under mild conditions. Using HEPC as a substrate, we have also developed a microplate assay for measuring phospholipase A2 activity which is rapid and will be useful for analyzing a large number of samples in a very short time. The applicability of this assay method for assessing phospholipases A2 from two different sources and determining their kinetic constants is also demonstrated. This method can also be extended for measuring lipases and lysophospholipases using a suitable thioester. Thus, both synthesis and assay methods will be useful in basic and applied research on phospholipases and related enzymes.
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Affiliation(s)
- M K Bhat
- AFRC Institute of Food Research, Department of Protein Engineering, Reading Laboratory, UK
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48
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Reichert A, Ringsdorf H, Wagenknecht A. Spontaneous domain formation of phospholipase A2 at interfaces: fluorescence microscopy of the interaction of phospholipase A2 with mixed monolayers of lecithin, lysolecithin and fatty acid. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1106:178-88. [PMID: 1581331 DOI: 10.1016/0005-2736(92)90237-g] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Fluorescence microscopy has recently been proven to be an ideal tool to investigate the specific interaction of phospholipase A2 with oriented substrate monolayers. Using a dual labeling technique, it could be shown that phospholipase A2 can specifically attack and hydrolyze solid analogous L-alpha-DPPC domains. After a critical extent of monolayer hydrolysis the enzyme itself starts to aggregate forming regular shaped protein domains (Grainger et al. (1990) Biochim. Biophys. Acta 1023, 365-379). In order to confirm that the existence of hydrolysis products in the monolayer is necessary for the observed aggregation of phospholipase A2, mixed monolayers of D- and L-alpha-DPPC, L-alpha-lysoPPC and palmitic acid in different ratios were examined. The phase behavior and the interaction of these films with phospholipase A2 were directly visualized with an epifluorescence microscope. Above a certain critical concentration of lysolecithin and palmitic acid in the monolayer, compression of these mixed films leads to phase separation and formation of mixed domains of unknown composition. Their high negative charge density is evidenced by preferential binding of a cationic dye to these phase-separated areas. Introduction of fluorescence-labeled phospholipase A2 underneath these mixed domains results in rapid binding of the protein to the domains without visible hydrolytic activity, regardless of whether the L-form or the D-form of the DPPC were used. In binary mixtures, only those with DPPC/palmitic acid show formation of phase-separated areas which can be specifically targeted by phospholipase A2 leading to a rapid formation (within 2 min) of protein domains. Experiments with pyrenedecanoic acid containing monolayers give the first direct evidence that acid is located above the enzyme domains. These results show that a locally high negative charge density of the phase-separated domains is one of the prerequisites for the binding of phospholipase A2. In addition, however, small amounts of D- or L-alpha-DPPC headgroups within the domains of the monolayer seem to be necessary for recognition followed by fast binding of the protein to the domains. This is confirmed by experiments with mixed monolayers of diacetylene carboxylic acid and D-alpha-DPPC. The acid--immiscible with lecithin--forms well defined pure acid domains in the monolayer. While the cationic dye can be docked rapidly to these phase separated areas, no preferential enzyme binding and thus no protein domain formation below these acid domains can be induced.
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Affiliation(s)
- A Reichert
- Institut für Organische Chemie, Universität Mainz, Germany
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Deveer AM, Franken PA, Dijkman R, Meeldijk J, Egmond MR, Verheij HM, Verger R, de Haas GH. Competitive inhibition of lipolytic enzymes. VII. The interaction of pancreatic phospholipase A2 with micellar lipid/water interfaces of competitive inhibitors. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1125:73-81. [PMID: 1567910 DOI: 10.1016/0005-2760(92)90158-r] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In a recent series of kinetic studies (De Haas et al. (1990) Biochim. Biophys. Acta 1046, 249-257 and references therein) we have demonstrated that synthetic (R)-phospholipid analogues containing a 2-acylaminogroup instead of the 2-acyloxy function found in natural phospholipids, behave as strong competitive inhibitors of porcine pancreatic phospholipase A2 (PLA2). We also showed that these analogues strongly bind to the active site of the enzyme but only after their incorporation into a micellar substrate/water interface. In the present study we investigated the interaction of native PLA2 and of an inactive PLA2 in which the active site residue His-48 has been modified by alkylation with 1-bromo-2-octanone, with pure micelles of several of these inhibitors in both enantiomeric forms by means of ultraviolet difference absorption spectroscopy. Our results show that the first interaction step between native or modified enzyme and micellar lipid/water interfaces probably consists of a low-affinity Langmuir-type adsorption characterized by signals arising from the perturbation of the single Trp-3 residue. Once present at the interface the native enzyme is able to bind, in a second step, a single inhibitor molecule of the (R)-configuration in its active site, whereas the (S)-enantiomer is not bound in the active site. The overall dissociation constant of the interfacial phospholipase-inhibitor complex is three orders of magnitude lower for micelles composed of the (R)-isomer than those of the (S)-isomer. The modified PLA2 still adsorbs to micellar lipid/water interfaces but cannot bind either of the two enantiomers into its active site and similar dissociation constants were found for lipid-protein complexes with micelles of either the (R) or the (S) inhibitors. After blanking the ultraviolet signals due to the perturbation of Trp-3 in the initial adsorption step of the enzyme to a micellar surface of a non-inhibitory phospholipid analogue, the progressive binding of a single (R)-inhibitor molecule into the active site could be followed quantitatively by a tyrosine perturbation. These titrations yielded numerical values for the dissociation constants in the interface and provide a possible explanation for the large difference in overall dissociation constants of the complexes between enzyme and micelles of (R)-and (S)-inhibitors. With the use of PLA2 mutants in which each time a single tyrosine was replaced by phenylalanine, the tyrosine residues involved in binding of the monomeric inhibitor molecule were identified as Tyr-69 and Tyr-52.
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Affiliation(s)
- A M Deveer
- Unilever Research, Vlaardingen, Netherlands
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50
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