1
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Modulation of gastric lipase adsorption onto mixed galactolipid-phospholipid films by addition of phytosterols. Colloids Surf B Biointerfaces 2022; 220:112933. [DOI: 10.1016/j.colsurfb.2022.112933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 09/20/2022] [Accepted: 10/13/2022] [Indexed: 11/27/2022]
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2
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sPLA2 Wobbles on the Lipid Bilayer between Three Positions, Each Involved in the Hydrolysis Process. Toxins (Basel) 2022; 14:toxins14100669. [PMID: 36287938 PMCID: PMC9610741 DOI: 10.3390/toxins14100669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 09/14/2022] [Accepted: 09/22/2022] [Indexed: 11/17/2022] Open
Abstract
Secreted phospholipases A2 (sPLA2s) are peripheral membrane enzymes that hydrolyze phospholipids in the sn-2 position. The action of sPLA2 is associated with the work of two active sites. One, the interface binding site (IBS), is needed to bind the enzyme to the membrane surface. The other one, the catalytic site, is needed to hydrolyze the substrate. The interplay between sites, how the substrate protrudes to, and how the hydrolysis products release from, the catalytic site remains in the focus of investigations. Here, we report that bee venom PLA2 has two additional interface binding modes and enzyme activity through constant switching between three different orientations (modes of binding), only one of which is responsible for substrate uptake from the bilayer. The finding was obtained independently using atomic force microscopy and molecular dynamics. Switching between modes has biological significance: modes are steps of the enzyme moving along the membrane, product release in biological milieu, and enzyme desorption from the bilayer surface.
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3
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Zhang F, Li X, Ma Y, Wang C, Hu P, Wang F, Lu X. Illustrating Interfacial Interaction between Honey Bee Venom Phospholipase A 2 and Supported Negatively Charged Lipids with Sum Frequency Generation and Laser Scanning Confocal Microscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:2946-2953. [PMID: 32093479 DOI: 10.1021/acs.langmuir.0c00003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Phospholipase A2 is an important enzyme species which can widely be found in animals, plants, bacteria, and so on. A large number of studies have shown that phospholipase A2 is highly catalytic toward the lipids. Here, sum frequency generation (SFG) vibrational spectroscopy and laser scanning confocal microscopy (LSCM) were applied to study the interaction between honey bee venom phospholipase A2 (bvPLA2) and the negatively charged DPPG bilayer. In both cases without and with the calcium ions (Ca2+), the bvPLA2 molecules were adsorbed onto the outer leaflet surface with the orientational order, and the adsorbed bvPLA2 molecules damaged the order of the packed outer leaflet. In comparison to the case without Ca2+, the addition of Ca2+ can accelerate the attaching process of bvPLA2 to the outer leaflet surface and decelerate the process of damaging the outer leaflet order. The experimental result also confirmed, with the help of the Ca2+, the DPPG molecules in the outer leaflet were hydrolyzed, with both hydrolysates, that is, lysophospholipids and fatty acids, remaining at the interface, showing a distinct difference from previous published literatures regarding neutral lipids [Phys. Chem. Chem. Phys. 2018, 20, 63-67] and PLA1 [Langmuir 2019, 35, 12831-12838].
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Affiliation(s)
- Furong Zhang
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Xu Li
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Yonghao Ma
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Chu Wang
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Pengcheng Hu
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Feng Wang
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Xiaolin Lu
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
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4
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Szcześ A. Effect of the enzymatically modified supported dipalmitoylphosphatidylcholine (DPPC) bilayers on calcium carbonate formation. Colloid Polym Sci 2016; 294:409-419. [PMID: 26855469 PMCID: PMC4733140 DOI: 10.1007/s00396-015-3796-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 09/21/2015] [Accepted: 10/20/2015] [Indexed: 11/25/2022]
Abstract
After an hour contact with a phospholipase A2 (PLA2) solution, only the outer leaflet of the dipalmitoylphosphatidylcholine (DPPC) bilayers supported on mica surface underwent hydrolysis whose products, i.e., palmitic acid and lysophospholipid, accumulated on the bilayer surface. Only calcite was present on the bare mica and enzymatically unmodified and modified supported DPPC bilayers soaked for 2 weeks at 25 and 37 °C in a solution of initial pH equals to 7.4 and 9.2 containing calcium and bicarbonate ions at their concentrations about those of human blood plasma. The DPPC bilayers accelerate the crystal growth at lower pH and favors CaCO3 nucleation at higher pH. Enzymatic modification of bilayers does not affect crystal morphology and its organization on the examined surface but causes a slight crystal size increase at lower pH and significantly reduces crystal size at alkaline pH. The temperature increase leads to the formation of bigger crystals under physiological pH and has almost no effect on crystal size at alkaline pH. The obtained results are probably attributed to Ca2+ interaction with a specific polar site on the surface of the membrane and DPPC hydrolysis products acting as nucleation centers.
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Affiliation(s)
- Aleksandra Szcześ
- Department of Physical Chemistry-Interfacial Phenomena, Faculty of Chemistry, Maria Curie-Skłodowska University, Lublin, 20-031 Poland
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5
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Wiącek AE, Adryańczyk E. Interfacial Properties of Phosphatidylcholine-based Dispersed Systems. Ind Eng Chem Res 2015. [DOI: 10.1021/acs.iecr.5b01429] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Agnieszka Ewa Wiącek
- Department of Interfacial
Phenomena, Faculty of Chemistry, Maria Curie-Skłodowska University, 20031 Lublin, Poland
| | - Emilian Adryańczyk
- Department of Interfacial
Phenomena, Faculty of Chemistry, Maria Curie-Skłodowska University, 20031 Lublin, Poland
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6
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7
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Gold/Phospholipid nanoconstructs as label-free optical probes for evaluating phospholipase A2 activity. Biosens Bioelectron 2014; 52:202-8. [DOI: 10.1016/j.bios.2013.08.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 08/03/2013] [Accepted: 08/12/2013] [Indexed: 11/17/2022]
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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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Morandat S, Azouzi S, Beauvais E, Mastouri A, El Kirat K. Atomic force microscopy of model lipid membranes. Anal Bioanal Chem 2012; 405:1445-61. [DOI: 10.1007/s00216-012-6383-y] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2012] [Revised: 08/02/2012] [Accepted: 08/24/2012] [Indexed: 10/27/2022]
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10
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Wiącek AE. Influence of dipalmitoylphosphatidylcholine (or dioleoylphosphatidylcholine) and phospholipase A2 enzyme on the properties of emulsions. J Colloid Interface Sci 2012; 373:75-83. [DOI: 10.1016/j.jcis.2011.09.037] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Revised: 09/15/2011] [Accepted: 09/16/2011] [Indexed: 10/17/2022]
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11
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Savinase action on bovine serum albumin (BSA) monolayers demonstrated with measurements at the air–water interface and liquid Atomic Force Microscopy (AFM) imaging. Colloids Surf B Biointerfaces 2011; 88:582-6. [DOI: 10.1016/j.colsurfb.2011.07.043] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2011] [Revised: 07/12/2011] [Accepted: 07/19/2011] [Indexed: 11/15/2022]
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12
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Investigation of DPPC effect on SiO2 particles and in the presence of phospho(lipases) by zeta potential and effective diameter measurements. POWDER TECHNOL 2011. [DOI: 10.1016/j.powtec.2011.07.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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13
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Changes in wetting properties of alumina surface treated with DPPC in the presence of phospholipase A2 enzyme. Colloids Surf B Biointerfaces 2011; 87:54-60. [DOI: 10.1016/j.colsurfb.2011.04.035] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Accepted: 04/30/2011] [Indexed: 11/17/2022]
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14
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The wetting and interfacial properties of alumina surface treated with dipalmitoylphosphatidylcholine and lipase enzyme. POWDER TECHNOL 2011. [DOI: 10.1016/j.powtec.2011.06.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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15
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Balashev K, Atanasov V, Mitewa M, Petrova S, Bjørnholm T. Kinetics of degradation of dipalmitoylphosphatidylcholine (DPPC) bilayers as a result of vipoxin phospholipase A2 activity: An atomic force microscopy (AFM) approach. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:191-8. [DOI: 10.1016/j.bbamem.2010.10.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Revised: 10/04/2010] [Accepted: 10/13/2010] [Indexed: 11/29/2022]
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16
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Ferguson EL, De Luca E, Heenan RK, King SM, Griffiths PC. Time-Resolved Small-Angle Neutron Scattering as a Tool for Studying Controlled Release from Liposomes using Polymer-Enzyme Conjugates. Macromol Rapid Commun 2010; 31:1685-90. [DOI: 10.1002/marc.201000241] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 06/06/2010] [Indexed: 11/05/2022]
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17
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Tong Y, Li N, Liu H, Ge A, Osawa M, Ye S. Mechanistic studies by sum-frequency generation spectroscopy: hydrolysis of a supported phospholipid bilayer by phospholipase A2. Angew Chem Int Ed Engl 2010; 49:2319-23. [PMID: 20209538 DOI: 10.1002/anie.200904950] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Yujin Tong
- Catalysis Research Centre, Hokkaido University, Sapporo 001-0021, Japan
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18
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Ocampo J, Afanador N, Vives MJ, Moreno JC, Leidy C. The antibacterial activity of phospholipase A2 type IIA is regulated by the cooperative lipid chain melting behavior in Staphylococcus aureus. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:1021-8. [DOI: 10.1016/j.bbamem.2009.11.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Revised: 10/31/2009] [Accepted: 11/24/2009] [Indexed: 11/29/2022]
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19
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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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20
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Sharbaugh DM, Talham DR. Effect of phospholipase A2 hydrolysis products on calcium oxalate precipitation at lipid interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:4925-4932. [PMID: 20000434 DOI: 10.1021/la903574v] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Urinary stones are commonly composed of an inorganic component, calcium oxalate, or calcium phosphate and an organic matrix of lipids, carbohydrates, and proteinaceous matter. Of interest is the role that the organic matrix elements may play as catalysts for the heterogeneous nucleation of the calcium salts, and a number of studies have examined the role of lipids in calcium oxalate monohydrate (COM) formation. In this study, products of lipid hydrolysis from phospholipase A(2) (PLA(2)) are examined for their effect on COM formation using Langmuir monolayers as model lipid membrane assemblies. The enzyme PLA(2) hydrolyzes DPPC monolayers in the presence of a supersaturated calcium oxalate subphase, inducing the rapid and plentiful nucleation of calcium oxalate at the lipid interface. To investigate the cause of increased crystal formation in the presence of the enzyme, Langmuir monolayers modeling the hydrolysis products were investigated. Calcium oxalate crystal growth at a ternary monolayer of dipalmitoylphosphatidylcholine (DPPC), palmitic acid (PA), and a 22-carbon chain lysophospholipid (22:0 Lyso PC) dramatically increases relative to monolayers of just DPPC. Binary monolayers of DPPC with either PA or the 22:0 Lyso PC and single-component monolayers of PA were also studied. It is demonstrated that the fatty acid generated during lipid hydrolysis causes a significant increase in the extent of heterogeneous nucleation of calcium oxalate from supersaturated solutions. The results imply a possible link between increased phospholipase activity, which is associated with hyperoxaluria, and calcium oxalate precipitation.
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Affiliation(s)
- Denise M Sharbaugh
- Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, USA
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21
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El Kirat K, Morandat S, Dufrêne YF. Nanoscale analysis of supported lipid bilayers using atomic force microscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:750-65. [DOI: 10.1016/j.bbamem.2009.07.026] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 07/17/2009] [Accepted: 07/23/2009] [Indexed: 12/11/2022]
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22
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Tong Y, Li N, Liu H, Ge A, Osawa M, Ye S. Mechanistic Studies by Sum-Frequency Generation Spectroscopy: Hydrolysis of a Supported Phospholipid Bilayer by Phospholipase A2. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.200904950] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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23
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Chemistry and Function of Phospholipids. FOOD SCIENCE AND TECHNOLOGY 2010. [DOI: 10.1201/9781420046649.ch2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
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24
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Chiu CR, Huang WN, Wu WG, Yang TS. Fluorescence Single-Molecule Study of Cobra Phospholipase A2Action on a Supported Gel-Phase Lipid Bilayer. Chemphyschem 2009; 10:549-58. [DOI: 10.1002/cphc.200800403] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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25
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Electrokinetic properties of n-tetradecane/ethanol emulsions with DPPC and enzyme lipase or phospholipase A2. Colloids Surf A Physicochem Eng Asp 2009. [DOI: 10.1016/j.colsurfa.2008.09.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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26
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Abstract
Formation of liquid-ordered domains in model membranes can be linked to raft formation in cellular membranes. The lipid stoichiometry has a governing influence on domain formation and consequently, biochemical hydrolysis of specific lipids has the potential to remodel domain features. Activation of phospholipase A(2) (PLA(2)) by ternary model membranes with three components (DOPC/DPPC/Cholesterol) can potentially change the domain structure by preferential hydrolysis of the phospholipids. Using fluorescence microscopy, this work investigates the changes in domain features that occur upon PLA(2) activation by such ternary membranes. Double-supported membranes are used, which have minimal interactions with the solid support. For membranes prepared in the coexistence region, PLA(2) induces a decrease of the liquid-disordered (L(d)) phase and an increase of the liquid-ordered (L(o)) phase. A striking observation is that activation by a uniform membrane in the L(d) phase leads to nucleation and growth of L(o)-like domains. This phenomenon relies on the initial presence of cholesterol and no PLA(2) activation is observed by membranes purely in the L(o) phase. The observations can be rationalized by mapping partially hydrolyzed islands onto trajectories in the phase diagram. It is proposed that DPPC is protected from hydrolysis through interactions with cholesterol, and possibly the formation of condensed complexes. This leads to specific trajectories which can account for the observed trends. The results demonstrate that PLA(2) activation by ternary membrane islands may change the global lipid composition and remodel domain features while preserving the overall membrane integrity.
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27
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Wagner K, Desbat B, Brezesinski G. Liquid–liquid immiscibility in model membranes activates secretory phospholipase A2. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:166-74. [DOI: 10.1016/j.bbamem.2007.09.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2007] [Revised: 09/17/2007] [Accepted: 09/19/2007] [Indexed: 01/16/2023]
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28
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Nielsen LK, Bjørnholm T, Mouritsen OG. Thermodynamic and real-space structural evidence of a 2D critical point in phospholipid monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:11684-11692. [PMID: 17929843 DOI: 10.1021/la7016352] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The two-dimensional phase diagram of phospholipid monolayers at air-water interfaces has been constructed from Langmuir compression isotherms. The coexistence region between the solid and fluid phases of the monolayer ends at the critical temperature of the transition. The small-scale lateral structure of the monolayers has been imaged by atomic force microscopy in the nm to microm range at distinct points in the phase diagram. The lateral structure is immobilized by transferring the monolayer from an air-water interface to a solid mica support using Langmuir-Blodgett techniques. A transfer protocol that ensures preservation of the structure during the transfer has been established. The lateral structure reflecting the density fluctuations has been visualized and quantitatively characterized as the monolayer passes through a series of first-order phase transitions and ultimately approaches a critical point. The critical behavior inferred from the thermodynamic as well as the structural data is found to be consistent with the 2D Ising universality class. Additional results are presented demonstrating the presence of striped phases and coexisting domains in binary mixtures.
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Affiliation(s)
- Lars K Nielsen
- Radiometer Medical, Akandevej 21, DK-2700 Brønshøj, Denmark
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29
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Wacklin HP, Tiberg F, Fragneto G, Thomas RK. Distribution of reaction products in phospholipase A2 hydrolysis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:1036-49. [PMID: 17355873 DOI: 10.1016/j.bbamem.2006.10.020] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2006] [Revised: 09/20/2006] [Accepted: 10/30/2006] [Indexed: 11/29/2022]
Abstract
We have monitored the composition of supported phospholipid bilayers during phospholipase A(2) hydrolysis using specular neutron reflection and ellipsometry. Porcine pancreatic PLA(2) shows a long lag phase of several hours during which the enzyme binds to the bilayer surface, but only 5+/-3% of the lipids react before the onset of rapid hydrolysis. The amount of PLA(2), which resides in a 21+/-1 A thick layer at the water-bilayer interface, as well as its depth of penetration into the membrane, increase during the lag phase, the length of which is also proportional to the enzyme concentration. Hydrolysis of a single-chain deuterium labelled d(31)-POPC reveals for the first time that there is a significant asymmetry in the distribution of the reaction products between the membrane and the aqueous environment. The lyso-lipid leaves the membrane while the number of PLA(2) molecules bound to the interface increases with increasing fatty acid content. These results constitute the first direct measurement of the membrane structure and composition, including the location and amount of the enzyme during hydrolysis. These are discussed in terms of a model of fatty-acid mediated activation of PLA(2).
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Affiliation(s)
- Hanna P Wacklin
- Oxford University, Physical and Theoretical Chemistry Laboratory, South Parks Road, Oxford OX1 3QZ, UK.
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30
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Cherney DP, Myers GA, Horton RA, Harris JM. Optically trapping confocal Raman microscopy of individual lipid vesicles: kinetics of phospholipase A(2)-catalyzed hydrolysis of phospholipids in the membrane bilayer. Anal Chem 2007; 78:6928-35. [PMID: 17007516 DOI: 10.1021/ac061049b] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Phospholipase A2 (PLA2)-catalyzed hydrolysis at the sn-2 position of 1,2-dimyristoyl-sn-glycero-3-phosphocholine in optically trapped liposomes is monitored in situ using confocal Raman microscopy. Individual optically trapped liposomes (0.6 microm in diameter) are exposed to PLA2 isolated from cobra (Naja naja naja) venom at varying enzyme concentrations. The relative Raman scattering intensities of C-C stretching vibrations from the trans and gauche conformers of the acyl chains are correlated directly with the extent of hydrolysis, allowing the progress of the reaction to be monitored in situ on a single vesicle. In dilute vesicle dispersions, the technique allows the much higher local concentration of lipid molecules in a single vesicle to be detected free of interferences from the surrounding solution. Observing the local composition of an optically trapped vesicle also allows one to determine whether the products of enzyme-catalyzed hydrolysis remain associated with the vesicle or dissolve into solution. The observed reaction kinetics exhibited a time lag prior to the rapid hydrolysis. The lag time varied inversely with the enzyme concentration, which is consistent with the products of enzyme-catalyzed lipid hydrolysis reaching a critical concentration that allows the enzyme to react at a much faster rate. The turnover rate of membrane-bound enzyme determined by Raman microscopy during the rapid, burst-phase kinetics was 1200 s(-1). Based on previous measurements of the equilibrium for PLA2 binding to lipid membranes, the average number of enzyme molecules responsible for catalyzing the hydrolysis of lipid on a single optically trapped vesicle is quite small, only two PLA2 molecules at the lowest enzyme concentration studied.
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Affiliation(s)
- Daniel P Cherney
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112-0850, USA
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Agafonov AV, Gritsenko EN, Shlyapnikova EA, Kharakoz DP, Belosludtseva NV, Lezhnev EI, Saris NEL, Mironova GD. Ca2+-induced phase separation in the membrane of palmitate-containing liposomes and its possible relation to membrane permeabilization. J Membr Biol 2007; 215:57-68. [PMID: 17443385 DOI: 10.1007/s00232-007-9005-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2006] [Accepted: 01/17/2007] [Indexed: 11/30/2022]
Abstract
A Ca(2+)-induced phase separation of palmitic acid (PA) in the membrane of azolectin unilamellar liposomes has been demonstrated with the fluorescent membrane probe nonyl acridine orange (NAO). It has been shown that NAO, whose fluorescence in liposomal membranes is quenched in a concentration-dependent way, can be used to monitor changes in the volume of lipid phase. The incorporation of PA into NAO-labeled liposomes increased fluorescence corresponding to the expansion of membrane. After subsequent addition of Ca(2+), fluorescence decreased, which indicated separation of PA/Ca(2+) complexes into distinct membrane domains. The Ca(2+)-induced phase separation of PA was further studied in relation to membrane permeabilization caused by Ca(2+) in the PA-containing liposomes. A supposition was made that the mechanism of PA/Ca(2+)-induced membrane permeabilization relates to the initial stage of Ca(2+)-induced phase separation of PA and can be considered as formation of fast-tightening lipid pores due to chemotropic phase transition in the lipid bilayer.
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Affiliation(s)
- Alexey V Agafonov
- Laboratory of Mitochondrial Transport, Institute of Theoretical and Experimental Biophysics RAS, Institutskaya str. 3, Pushchino, Moscow Region 142290, Russia.
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Balashev K, John DiNardo N, Callisen TH, Svendsen A, Bjørnholm T. Atomic force microscope visualization of lipid bilayer degradation due to action of phospholipase A2 and Humicola lanuginosa lipase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1768:90-9. [PMID: 17084807 DOI: 10.1016/j.bbamem.2006.09.028] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2006] [Revised: 09/25/2006] [Accepted: 09/26/2006] [Indexed: 11/25/2022]
Abstract
An important application of liquid cell Atomic Force Microscopy (AFM) is the study of enzyme structure and behaviour in organized molecular media that mimic in-vivo systems. In this study we demonstrate the use of AFM as a tool to study the kinetics of lipolytic enzyme reactions occurring at the surface of a supported lipid bilayer. In particular, the time course of the degradation of lipid bilayers by Phospholipase A(2) (PLA(2)) and Humicola Lanuginosa Lipase (HLL) has been investigated. Contact mode imaging allows visualization of enzyme activity on the substrate with high lateral resolution. Lipid bilayers were prepared by the Langmuir-Blodgett technique and transferred to an AFM liquid cell. Following injection of the enzyme into the liquid cell, a sequence of images was acquired at regular time intervals to allow the identification of substrate structure, preferred sites of enzyme activation, and enzyme reaction rates.
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Affiliation(s)
- Konstantin Balashev
- Sofia University, Department of Physical Chemistry, Lab. of Biophysical Chemistry, Sofia 1164, 1, James Bourchier Ave., Bulgaria.
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Aloulou A, Rodriguez JA, Fernandez S, van Oosterhout D, Puccinelli D, Carrière F. Exploring the specific features of interfacial enzymology based on lipase studies. Biochim Biophys Acta Mol Cell Biol Lipids 2006; 1761:995-1013. [PMID: 16931141 DOI: 10.1016/j.bbalip.2006.06.009] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2006] [Revised: 06/17/2006] [Accepted: 06/27/2006] [Indexed: 11/28/2022]
Abstract
Many enzymes are active at interfaces in the living world (such as in the signaling processes at the surface of cell membranes, digestion of dietary lipids, starch and cellulose degradation, etc.), but fundamental enzymology remains largely focused on the interactions between enzymes and soluble substrates. The biochemical and kinetic characterization of lipolytic enzymes has opened up new paths of research in the field of interfacial enzymology. Lipases are water-soluble enzymes hydrolyzing insoluble triglyceride substrates, and studies on these enzymes have led to the development of specific interfacial kinetic models. Structure-function studies on lipases have thrown light on the interfacial recognition sites present in the molecular structure of these enzymes, the conformational changes occurring in the presence of lipids and amphiphiles, and the stability of the enzymes present at interfaces. The pH-dependent activity, substrate specificity and inhibition of these enzymes can all result from both "classical" interactions between a substrate or inhibitor and the active site, as well as from the adsorption of the enzymes at the surface of aggregated substrate particles such as oil drops, lipid bilayers or monomolecular lipid films. The adsorption step can provide an alternative target for improving substrate specificity and developing specific enzyme inhibitors. Several data obtained with gastric lipase, classical pancreatic lipase, pancreatic lipase-related protein 2 and phosphatidylserine-specific phospholipase A1 were chosen here to illustrate these specific features of interfacial enzymology.
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Affiliation(s)
- Ahmed Aloulou
- Laboratoire d'Enzymologie Interfaciale et de Physiologie de la Lipolyse, CNRS UPR 9025, 31 Chemin Joseph Aiguier, 13009 Marseille Cedex 20, France
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Balashev K, Gudmand M, Iversen L, Callisen TH, Svendsen A, Bjørnholm T. Humicola lanuginosa lipase hydrolysis of mono-oleoyl-rac-glycerol at the lipid-water interface observed by atomic force microscopy. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1615:93-102. [PMID: 12948591 DOI: 10.1016/s0005-2736(03)00209-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new type of planar lipid substrate for Humicola lanuginosa lipase (HLL) has been prepared by depositing a monolayer of 1-mono-oleoyl-rac-glycerol (MOG) on top of a monolayer of dipalmitoyl-phosphatidylcholine (DPPC) on mica by the Langmuir-Blodgett (LB) technique. The bilayer was subsequently exposed to HLL in a liquid cell of an atomic force microscope (AFM) allowing the time course of the lipolytic degradation to be observed. By analysing a series of AFM images, we find that enzymes are preferentially activated at the edge of nano-scale defects present in the bilayer prior to enzyme injection, while defect-free areas of the substrate are surprisingly stable towards enzyme degradation. The initial rate of hydrolysis is found to be proportional to the perimeter length, P, of the initial nano-scale defects as well as the bulk enzyme concentration, c(HLL); d(lipid)/dt=k P c(HLL). We estimate the specific rate of MOG hydrolysis by HLL to be 2.5x10(4) MOG molecules/(minute x molecule of HLL).
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Affiliation(s)
- Konstantin Balashev
- Department of Chemistry, Nano-Science Center, University of Copenhagen, Denmark
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