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Adamson K, Dolan C, Moran N, Forster RJ, Keyes TE. RGD Labeled Ru(II) Polypyridyl Conjugates for Platelet Integrin αIIbβ3 Recognition and as Reporters of Integrin Conformation. Bioconjug Chem 2014; 25:928-44. [DOI: 10.1021/bc5000737] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Kellie Adamson
- School
of Chemical Sciences, Dublin City University, Dublin 9, Ireland
| | - Ciaran Dolan
- School
of Chemical Sciences, Dublin City University, Dublin 9, Ireland
| | - Niamh Moran
- The
Department of Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin 2, Ireland
| | - Robert J. Forster
- School
of Chemical Sciences, Dublin City University, Dublin 9, Ireland
| | - Tia E. Keyes
- School
of Chemical Sciences, Dublin City University, Dublin 9, Ireland
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García-Guerra R, García-Domínguez JA, González-Rodríguez J. A new look at the lipid composition of the plasma membrane of human blood platelets relative to the GPIIb/IIIa (integrin cxIIβ3) content. Platelets 2012; 7:195-205. [PMID: 21043688 DOI: 10.3109/09537109609023579] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The total lipids of the human platelet plasma membrane (HPPM) from 50 ml of blood of healthy subjects were extracted, quantified and related to the mass content of the major intrinsic membrane protein, the glycoprotein IIb/IIIa (GPIIb/IIIa). The HPPM total lipid/GPIIb/IIIa weight ratio determined was 5.40 ± 0.20, independently of the membrane washing procedure used, with the cholesterol/GPIIb/IIIa and phospholipid/GPIIb/IIIa molar ratios of 800 ± 50 and 1200 ± 40, respectively. If the distribution of lipids around each intrinsic protein were proportional to its mass, the lipids around a molecule of GPIIb/IIIa will occupy about 120 nm(2) of the membrane plane, which is about one and a half times the cross-sectional area of the extracellular head of GPIIb/IIIa, as estimated by electron microscopy. The lipid extracts were further subjected to thin-layer chromatography to separate and quantify the different phospholipid fractions, the free fatty acids and the neutral lipid fraction and the distribution of fatty acids in each fraction was determined by gas chromatography after methanolysis. The phospholipid molar distribution was SPM(22.3 ± 0.9%), PC(36.2 ± 1.0%), PE(24.9 ± 0.9%), PS(12.1 ± 0.6%) and PI(4.5 ± 0.4%) and the free fatty acid fraction represented 2.9 ± 0.4% of the total fatty acids in HPPM. The fatty acid chain length ranged from 14 to 24 carbons, comprising unsaturated fatty acids (47.3% molar per cent of the total) of which 40.7 ± 2.0% were monosaturated and 40.7 ± 0.9% tetraunsaturated. Palmitic, stearic, oleic and arachidonic acids represent 66% of the total fatty acids of HPPM, being: 68.9 ± 5.3% of palmitic acid and 63.3 ± 6.9% of oleic acid in PC; 50.9 ± 3.8% of arachidonic acid in PE; and 30.5 ± 2.4% of stearic acid in PS. We discuss the methodological modifications and the new data in relation with the major differences in HPPM lipid composition found in the literature. The data obtained provides a comprehensive and accurate description of the lipid composition of HPPM on which to rely as a reference for basic and medical studies.
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Affiliation(s)
- R García-Guerra
- Departamento de Biofísica, Instituto de Química Física, C.S.I.C., Serrano 119, E-28006, Madrid, Spain
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Yan Y, Li Y, Zhang S, Ai C. Studies of tricyclic piperazine/piperidine furnished molecules as novel integrin αvβ3/αIIbβ3 dual antagonists using 3D-QSAR and molecular docking. J Mol Graph Model 2011; 29:747-62. [PMID: 21273104 DOI: 10.1016/j.jmgm.2010.12.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Revised: 12/10/2010] [Accepted: 12/20/2010] [Indexed: 10/18/2022]
Abstract
The development of injectable integrin α(v)β(3)/α(IIb)β(3) dual antagonists attracts much attention of research for treating of acute ischemic diseases in recent years. In this work, based on a dataset composed of 102 tricyclic piperazine/piperidine furnished dual α(v)β(3) and α(IIb)β(3) antagonists, a variety of in silico modeling approaches including the comparative molecular field analysis (CoMFA), comparative similarity indices analysis (CoMSIA), and molecular docking were applied to reveal the requisite 3D structural features impacting the biological activities. Our statistical results show that the ligand-based 3D-QSAR models for both the α(v)β(3) and α(IIb)β(3) studies exhibited satisfactory internal and external predictability, i.e., for the CoMFA models, results of Q(2)=0.48, R(ncv)(2)=0.87, R(pred)(2)=0.71 for α(v)β(3) and Q(2)=0.50, R(ncv)(2)=0.85, R(pred)(2)=0.72 for α(IIb)β(3) analysis were obtained, and for the CoMSIA ones, the outcomes of Q(2)=0.55, R(ncv)(2)=0.90, R(pred)(2)=0.72 for α(v)β(3) and Q(2)=0.52, R(ncv)(2)=0.88, R(pred)(2)=0.74 for α(IIb)β(3) were achieved respectively. In addition, through a comparison between 3D-QSAR contour maps and docking results, it is revealed that that the most crucial interactions occurring between the tricyclic piperazine/piperidine derivatives and α(v)β(3)/α(IIb)β(3) receptor ligand binding pocket are H-bonding, and the key amino acids impacting the interactions are Arg214, Asn215, Ser123, and Lys253 for α(v)β(3), but Arg214, Asn215, Ser123 and Tyr190 for α(IIb)β(3) receptors, respectively. Halogen-containing groups at position 15 and 16, benzene sulfonamide substituent at position 23, and the replacement of piperazine with 4-aminopiperidine of ring B may increase the α(v)β(3)/α(IIb)β(3) antagonistic activity. The potencies for antagonists to inhibit isolated α(v)β(3) and α(IIb)β(3) are linear correlated, indicating that similar interaction mechanisms may exist for the series of molecules. To our best knowledge this is the first report on 3D-QSAR modeling of these dual α(v)β(3)/α(IIb)β(3) antagonists. The results obtained should provide information for better understanding of the mechanism of antagonism and thus be helpful in design of novel potent dual α(v)β(3)/α(IIb)β(3) antagonists.
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Affiliation(s)
- Yulian Yan
- School of Chemical Engineering, Dalian University of Technology, Dalian, 116012, Liaoning, China
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Hemmilá I, Mukkala VM. Time-Resolution in Fluorometry Technologies, Labels, and Applications in Bioanalytical Assays. Crit Rev Clin Lab Sci 2008. [DOI: 10.1080/20014091084254] [Citation(s) in RCA: 194] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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5
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Coutinho A, García C, González-Rodríguez J, Lillo MP. Conformational changes in human integrin alphaIIbbeta3 after platelet activation, monitored by FRET. Biophys Chem 2007; 130:76-87. [PMID: 17714854 DOI: 10.1016/j.bpc.2007.07.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2007] [Revised: 07/25/2007] [Accepted: 07/26/2007] [Indexed: 11/16/2022]
Abstract
Integrin alpha(IIb)beta(3), an abundant heterodimeric receptor at the surface of blood platelets, binds adhesive proteins after platelet activation and plays a primary role in haemostasis. In solution, it has been observed mainly in two conformations: the bent and the extended forms. Based on X-ray crystallography, electron microscopy and immunochemical observations of full-length integrin ectodomains and intact integrins, it has been agreed that unactivated integrins are in the bent conformation, both isolated in solution and in living cells. However, consensus is yet to emerge on the bent or extended conformation of activated integrins and on their mechanism of activation (the switchblade, the deadbolt and the S-S reduction models), which require further experimental tests at the cell level to become established facts. Here, we tested the proposed structural rearrangements undergone by integrin alpha(IIb)beta(3) after cell activation, by using Förster-type fluorescence resonance energy transfer (FRET) and attached fluorescent labels to Fab fragments of monoclonal antibodies directed to the betaA domain of the beta(3) subunit (donor, Alexa488-P97 Fab) and to the Calf-2 domain of the alpha(IIb) subunit (acceptor, Cy3-M3 Fab or Cy3-M10 Fab). The FRET efficiencies observed after ADP or TRAP platelet activation changed less than 20% from the resting values, showing that the distance between the labeled Fab fragments changes only modestly after platelet activation by physiological agonists. This observation is consistent with a conformational model of the activated integrin in the cell less extended than in the switchblade model.
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Affiliation(s)
- Ana Coutinho
- Departamento de Biofísica, Instituto de Química Física Rocasolano. Consejo Superior de Investigaciones Científicas, Serrano 119. 28006 Madrid, Spain
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Purrucker O, Förtig A, Jordan R, Sackmann E, Tanaka M. Control of frictional coupling of transmembrane cell receptors in model cell membranes with linear polymer spacers. PHYSICAL REVIEW LETTERS 2007; 98:078102. [PMID: 17359064 DOI: 10.1103/physrevlett.98.078102] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2006] [Indexed: 05/14/2023]
Abstract
The planar plasma membrane model with linear polymer spacers with defined lengths enables the control of the frictional coupling between incorporated transmembrane proteins (human platelet integrin) and the solid substrate. This mimics the viscous environment provided by the extracellular matrix of cells. The friction coefficient can be calculated quantitatively from the diffusion coefficient of integrin, measured by fluorescence recovery after photobleaching. The obtained results demonstrate a clear influence of the length and lateral density of polymer chains on the mobility of transmembrane proteins.
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Affiliation(s)
- Oliver Purrucker
- Lehrstuhl für Biophysik E22, Technische Universität München, D85748 Garching, Germany
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Calzada MJ, Alvarez MV, Gonzalez-Rodriguez J. Agonist-specific structural rearrangements of integrin alpha IIbbeta 3. Confirmation of the bent conformation in platelets at rest and after activation. J Biol Chem 2002; 277:39899-908. [PMID: 12140290 DOI: 10.1074/jbc.m205886200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Concrete structural features of integrin alpha(IIb)beta(3) on the surface of platelets (at rest and after activation) have been obtained from epitope maps based on cross-competition among monoclonal antibodies directed against the alpha(IIb) subunit calf-2 domain and the beta(3) subunit betaA domain of alpha(IIb)beta(3). At rest, the observed intersubunit interface is formed by the sequence stretches beta(3)-(150-216), alpha(IIb) light chain-(1-92), and alpha(IIb) heavy chain-(826-856); and the alpha(IIb) interchain interface is formed by the two latter sequence stretches, disulfide-bonded between alpha(IIb) heavy chain Cys(826) and alpha(IIb) light chain Cys(9). These structural features agree with those observed in the alpha(IIb)beta(3) rudimentary connectivity map in solution and with the alpha(v)beta(3) V-shaped crystal structure (Xiong, J.-P., Zhang, R., Dunker, R., Scott, D. L., Joachimiak, A., Goodman, S. L., and Arnaout, M. A. (2001) Science 294, 339-345), but they disagree with the domain disposition suggested by the actual ultrastructural model. The epitope maps in platelets activated by ADP, thrombin receptor activation peptide, and arachidonic acid differ not only from those in platelets at rest, but also among themselves. The structural rearrangements observed confirm the presence in activated platelets of the crystallographically observed knee and argue against the switchblade mechanism proposed for activation (Beglova, N., Blacklow, S. C., Takagi, J., and Springer, T. A. (2002) Nat. Struct. Biol. 9, 282-287), demonstrate the existence of alpha(IIb)beta(3) agonist-specific activation states, explain the specificity for ligand binding and functional inhibition for some agonists, and predict the existence of agonist-specific final effectors and receptor activation mechanisms. The distinct non-reciprocal competition patterns observed at rest and after activation support the agonist-specific activation states and the existence of intrasubunit and intersubunit allosteric effects, previously proposed as the mechanism for alpha(IIb)beta(3) transmembrane activation.
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Affiliation(s)
- Maria J Calzada
- Departamento de Biofisica Molecular, Instituto de Quimica Fisica, Consejo Superior de Investigaciones Cientificas, Serrano 119, E-28006 Madrid, Spain
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Hall MW, Goodman PD, Alston SM, Solen KA. Hypothermia-induced platelet aggregation in heparinized flowing human blood: identification of a high responder subpopulation. Am J Hematol 2002; 69:45-55. [PMID: 11835331 DOI: 10.1002/ajh.10018] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Cold-induced platelet aggregation (CIPA) in PRP has previously been documented in connection with platelet preservation (4-15 degrees C). This report describes hypothermia-induced platelet aggregation (HIPA) in whole blood and at temperatures used in open-heart surgery (24-32 degrees C). HIPA (specifically, the formation of occlusive aggregates) was studied in human whole blood. Fresh heparinized (1.5 U/ml) human blood was cooled and maintained at target temperatures (15, 20, 24, 28, 32, or 37 degrees C) as it flowed (1 ml/min) through 75-cm long 1/32 inches internal diameter polymer conduit. The formation of aggregates in the tubing was verified using optical video microscopy and was quantified by a light-scattering method and a constant-pressure filtration method. Donors were tested at least twice at each target temperature and were classified into three separate response regimes (Low, Medium, and High) on the basis of the number of aggregates and the duration of their appearance. The screening of 121 donors (average age 22.3 +/- 4.3 years) for HIPA at 24 degrees C (the temperature of maximum response) indicated 14% High Responders, 18% Medium Responders, and 68% Low Responders. HIPA was inhibited by EDTA, citrate, PGE1, and Tirofiban, but not by aspirin, and it was enhanced by elevated heparin levels. HIPA was consistently noted in the blood of a subpopulation of donors, and the associated platelet aggregates in the blood of High Responders were rigid and occlusive. It is postulated that such aggregates may contribute to cognitive dysfunction noted in patients undergoing hypothermic open-heart surgery, and that postulus is being investigated.
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Mátyus L, Bene L, Hársfalvi J, Alvarez MV, González-Rodríguez J, Jenei A, Muszbek L, Damjanovich S. Organization of the glycoprotein (GP) IIb/IIIa heterodimer on resting human platelets studied by flow cytometric energy transfer. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2001; 65:47-58. [PMID: 11748005 DOI: 10.1016/s1011-1344(01)00255-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Glycoprotein IIb/IIIa is a heterodimer of glycoproteins IIb and IIIa which serves as the inducible receptor for fibrinogen and other adhesive proteins at the surface of platelets. Although a model of the quaternary structure of the GPIIb/IIIa molecule has been constructed in solution by Calvete et al. [Biochem. J. 282 (1992) 523], a corresponding model at the surface of intact platelets is still missing. In the present work conformation and lateral distribution of the GPIIb/IIIa heterodimer were studied at a nanometer resolution on the surface of resting human platelets under physiological conditions. The experiments were based on dual wavelength flow cytometric detection of fluorescence resonance energy transfer and application of a panel of monoclonal antibodies raised against well described binding sites. Monodisperse distribution of the GPIIb/IIIa heterodimer has been observed and a detailed three-dimensional proximity map of antibody binding sites was constructed on the platelet membrane, under physiological conditions, for the first time. Our data support the view that the GPIIb subunit is in a bent conformation. A detailed analysis of the K(d)-values and the number of binding sites for a set of monoclonal antibodies was also carried out giving supplementary data for the topology of the binding sites. Our results provide a refinement of the membrane-topology of the GPIIb/IIIa heterodimer.
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Affiliation(s)
- L Mátyus
- Department of Biophysics and Cell Biology, University of Debrecen, Nagyerdei krt 98, H-4012 Debrecen, Hungary.
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Li L, Castellano FN, Gryczynski I, Lakowicz JR. Long-lifetime lipid rhenium metal-ligand complex for probing membrane dynamics on the microsecond timescale. Chem Phys Lipids 1999; 99:1-9. [PMID: 10377961 PMCID: PMC6938644 DOI: 10.1016/s0009-3084(99)00002-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We report the luminescence and spectral properties of a phospholipid analogue containing a long-lifetime luminescent rhenium metal-ligand complex (MLC) covalently linked to the amino group of phosphatidyl ethanolamine. When incorporated into synthetic membranes, this lipid probe displays intensity decay times near 3 microseconds. Importantly, the probe displays highly polarized emission with a maximal fundamental anisotropy of 0.33. This probe is expected to have numerous applications for studies of microsecond diffusion and dynamics of membranes.
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Affiliation(s)
- Li Li
- Center for Fluorescence Spectroscopy, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, MD 21201, USA
| | - Felix N. Castellano
- Center for Fluorescence Spectroscopy, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, MD 21201, USA
| | - Ignacy Gryczynski
- Center for Fluorescence Spectroscopy, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, MD 21201, USA
| | - Joseph R. Lakowicz
- Center for Fluorescence Spectroscopy, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, MD 21201, USA
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11
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Duchowicz R, Ferrer ML, Acuñ AU. Kinetic Spectroscopy of Erythrosin Phosphorescence and Delayed Fluorescence in Aqueous Solution at Room Temperature. Photochem Photobiol 1998. [DOI: 10.1111/j.1751-1097.1998.tb02505.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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12
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Guo XQ, Castellano FN, Li L, Lakowicz JR. A long-lifetime Ru(II) metal-ligand complex as a membrane probe. Biophys Chem 1998; 71:51-62. [PMID: 9591359 DOI: 10.1016/s0301-4622(97)00135-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A luminescent metal-ligand complex, [Ru(bpy)2(dppz)]2+, (where dppz is dipyrido[3,2-a:2',3'-c] phenazine), was used as a photoluminescence probe for investigating submicrosecond lipid dynamics in a dipalmitoyl-L-alpha-phosphotidylglycerol (DPPG) model bilayer system. The luminescence of [Ru(bpy)2(dppz)]2+ in buffer is completely quenched but becomes luminescent when intercalated into DPPG vesicles. The experimental results show that the emission intensity of [Ru(bpy)2(dppz)]2+ intercalated into DPPG vesicles increases dramatically as temperature is increased towards the lipid phase transition temperature. This effect is abolished in bilayers containing a high concentration (> 30 mol%) of cholesterol, suggesting this probe is sensitive to the membrane composition. Frequency-domain emission intensity decays, measured as a function of increasing temperature towards the lipid phase transition temperature (2 to 57 degrees C), display two major lifetime components. The short lifetime disappears at temperatures well above the phase transition temperature. A comparison of oxygen quenching with iodide quenching suggests the heterogeneity of probe location at temperatures well below the lipid phase transition temperature and the homogeneity of probe location at temperature well above the lipid phase transition temperature. [Ru(bpy)2(dppz)]2+ displays polarized emission, enabling the study of membrane dynamics. The long decay time displayed by this probe allows measurement of the overall rotational correlation time of lipid vesicles on the microsecond time-scale. Because of the long lifetime, polarized emission, and background free nature of the photoluminescence measurements, [Ru(bpy)2(dppz)]2+ has numerous applications in the biophysical studies of membranes.
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Affiliation(s)
- X Q Guo
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore 21201, USA
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13
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Defilippi P, Venturino M, Gulino D, Duperray A, Boquet P, Fiorentini C, Volpe G, Palmieri M, Silengo L, Tarone G. Dissection of pathways implicated in integrin-mediated actin cytoskeleton assembly. Involvement of protein kinase C, Rho GTPase, and tyrosine phosphorylation. J Biol Chem 1997; 272:21726-34. [PMID: 9268301 DOI: 10.1074/jbc.272.35.21726] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
A panel of antibodies to the alphaIIbbeta3 integrin was used to promote adhesion of Chinese hamster ovary cells transfected with the alphaIIbbeta3 fibrinogen receptor. While some alphaIIbbeta3 antibodies were not able to induce p125 focal adhesion kinase (p125FAK) tyrosine phosphorylation, all the antibodies equally support cell adhesion but not spreading and assembly of actin stress fibers. Absence of stress fibers was also obtained by plating on antibodies directed to the hamster beta1 integrin. In contrast, cells plated on matrix proteins spread organizing actin stress fibers. Treatment with phorbol esters phorbol 12-myristate 13-acetate (PMA) induced cells to spread on antibodies-coated dishes but not to organize actin in stress fibers. The combination of PMA and cytotoxic necrotizing factor 1 (CNF1), a specific Rho activator, induced cell spreading and organization of stress fibers. PMA or the combination of PMA and CNF1 also increases tyrosine phosphorylation of p125FAK in response to antibodies that were otherwise unable to trigger this response. These data show that: 1) matrix proteins and antibodies differ in their ability to induce integrin-dependent actin cytoskeleton organization (while matrix induced stress fibers formation, antibodies did not); 2) p125FAK tyrosine phosphorylation is insufficient per se to trigger actin stress fibers formation since antibodies that activate p125FAK tyrosine phosphorylation did not lead to actin stress fibers assembly; and 3) the inability of anti-integrin antibodies to trigger stress fibers organization is overcome by concomitant activation of the protein kinase C (PKC) and Rho pathways; PKC activation leads to cell spreading and Rho activation is required to organize actin stress fibers.
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Affiliation(s)
- P Defilippi
- Dipartimento di Genetica, Biologia e Chimica Medica, Universita' di Torino, 10126 Torino, Italy.
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14
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Saturation effects on phosphorescence anisotropy measurements at high laser pulse energies. J Fluoresc 1997. [DOI: 10.1007/bf02760505] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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15
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16
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Li L, Szmacinski H, Lakowicz JR. Synthesis and luminescence spectral characterization of long-lifetime lipid metal-ligand probes. Anal Biochem 1997; 244:80-5. [PMID: 9025912 PMCID: PMC6906605 DOI: 10.1006/abio.1996.9869] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We synthesized phospholipid analogues of phosphatidyl ethanolamine which contains a ruthenium metal-ligand complex (MLC) covalently bound to the amino group. Two analogues were synthesized, containing either one (Ru-PE) or two (Ru-PE2) lipid molecules covalently linked to the MLC by the amino group of the lipid. These MLC-lipid probes display intensity decay times from 682 to 357 ns, depending on temperature. Importantly, the luminescence MLC groups display polarized emission, enabling their use for studies of membrane dynamics. The long intensity decay times allowed measurement of the overall rotation correlation time of lipid vesicles to several microseconds. The spectral properties of the model membranes containing Ru-PE or Ru-PE2 were independent of the probe-to-lipid molar ratio from 1:20 to 1:100, suggesting minimal tendency for probe-probe interactions. These MLC-lipid probes can be expected to have numerous applications in studies of membrane dynamics on the microsecond timescale.
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Affiliation(s)
- L Li
- Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, Baltimore 21201, USA
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17
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Nishio H, Kagawa T, Nezasa K, Nakata Y. Inhibitory effect of EGTA on serotonin transport into rabbit blood platelets: possible involvement of the glycoprotein IIb/IIIa complex. JAPANESE JOURNAL OF PHARMACOLOGY 1996; 72:255-9. [PMID: 8957687 DOI: 10.1254/jjp.72.255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We reported previously that serotonin (5-HT) transport was attenuated by treatment of platelets with EGTA, and that this inhibitory effect of EGTA was restored by CaCl2. In the present study, the inhibitory effect of EGTA was found to be uncompetitive, and no inhibitory effect was observed when EGTA was added at 20 degrees C. Genistein and thyrphostin A47, both protein tyrosine kinase inhibitors, inhibited Ca(2+)-induced restoration of 5-HT transport. In contrast, the protein tyrosine phosphatase inhibitor phenylarsine oxide significantly augmented Ca(2+)-induced restoration of 5-HT transport. These results might support the hypothesis that the glycoprotein (GP) IIb/IIIa complex, a platelet membrane integrin protein, might regulate 5-HT transport into blood platelets. It is conceivable that Ca2+ chelation by EGTA might cause temperature-dependent dissociation of the GP IIb/IIIa complex, which results in the reduction of 5-HT transport. Rearrangement of the GP IIb/IIIa complex by replenishment of the Ca2+ binding sites might restore the EGTA-induced reduction of 5-HT transport.
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Affiliation(s)
- H Nishio
- Department of Pharmacology, Hiroshima University School of Medicine, Japan
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18
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Calvete JJ, Schafer W, Mann K. Mass Spectrometric Analysis of the Phosphorylation State of Human Platelet Glycoprotein IIIa. Platelets 1995; 6:265-9. [DOI: 10.3109/09537109509023565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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