Combination Of Surface Plasmon Resonance Research Articles

SPR-MS in functional proteomics

The mapping of protein networks and the establishment of the functional relationships between expressed proteins and their effects on cellular processes represents a great challenge for functional or interaction proteomics. The combination of surface plasmon resonance (SPR)-based technology with mass spectrometry (MS) has created a unique analytical tool for functional proteomics investigations. Proteins are affinity purified, quantified and characterised in terms of their interactions, while the mass spectrometer identifies and structurally characterises the biomolecules. Recent developments have led to a closer integration of these key technologies, providing a combined approach which enables identification of proteins selected on the basis of their functional binding criteria. In addition to a historical overview of this field, some recent detailed examples of combined SPR-MS approaches will be reviewed in a number of key application areas, including ligand fishing, peptide sequence and post-translational modification analysis by SPR-MS/MS and enzyme inhibitor screening.

Specific interaction between Smad1 and CHIP: a surface plasmon resonance study

The TGF-β superfamily signaling pathway regulates many important biological processes, including cell growth, differentiation and embryonic pattern formation. Smad1, a member of this signaling pathway that functions downstream of serine/threonine kinase receptors, has ability to interact with carboxyl terminus of Hsc70-interacting protein (CHIP), which is an E3 ubiquitin ligase in other cases. It has been reported that Smurf1, a member of the Hect family E3 ubiquitin ligases, can target Smad1 to 26S proteasome for degradation. In this paper, we studied the interaction of Smad1 and CHIP by combination of surface plasmon resonance and supported monolayer approach. The specific binding of Smad1 to CHIP indicates that the degradation of Smad1 may also be mediated by CHIP, and CHIP may play an essential role in the TGF-β signaling pathway.

Combining Surface Plasmon Resonance and Quartz Crystal Microbalance for the in Situ Investigation of the Electropolymerization and Doping/Dedoping of Poly(pyrrole)

An in situ combination of surface plasmon resonance (SPR) spectroscopy and quartz crystal microbalance (QCM) is used to study the electropolymerization and the doping/dedoping behavior of thin poly(pyrrole) (ppy) films in aqueous solutions. A mixed anion and cation exchange behavior is observed. The mass as determined with the QCM continuously increases during redox cycling. The combined QCM/SPR data reveal that this is caused by a relatively slow process occurring when ppy is in the oxidized (polaronic) state. This behavior is interpreted as an accumulation of neutral salt and solvent in the film.

High-sensitivity sensor based on surface plasmon resonance and heterodyne interferometry

A common-path, heterodyne interferometric system for investigation of the phase variations under surface plasmon resonance (SPR) is presented. With the combination of SPR and total internal reflection (TIR), the system has the merits of avoiding direction change in the output light and increasing sensitivity. The system utilizes a pair of orthogonally linearly polarized beams with heterodyne frequency of 60 kHz as the light source. Because the two beams are perfectly collinear, the noises resulting from the ambient conditions are greatly reduced. Compared to reflectivity variation measurement, which is widely used in traditional SPR, the phase variation measurement using common-path, heterodyne techniques is approximately an order of magnitude higher in sensitivity and thus can be used as a high-sensitivity-demanded biosensor.

The μ2 Subunit of the Clathrin Adaptor AP‐2 Binds to FDNPVY and YppØ Sorting Signals at Distinct Sites

The endocytic sorting signal on the low-density lipoprotein receptor for clathrin-mediated internalization is the sequence FDNPVY in the receptor's cytosolic tail. We have used a combination of surface plasmon resonance and crosslinking with a photoactivated peptide probe to demonstrate the interaction between FDNPVY-containing peptides and the mu2 chain of purified AP-2 clathrin adaptors (the complexes responsible for plasma membrane sorting). We show that recognition of the FDNPVY signal is mediated by a binding site in the mu2-subunit that is distinct from the site for the more general YppØ sorting signal, another tyrosine-based sequence also recognized by mu2-adaptin. These results suggest the possibility that low-density lipoprotein receptor uptake may be modulated specifically and independently of other proteins in the clathrin pathway.

Comparative studies with surface plasmon resonance and free oscillation rheometry on the inhibition of platelets with cytochalasin E and monoclonal antibodies towards GPIIb/IIIa

In the haemostatic system a multitude of processes are intertwined in fine-tuned interactions that arrest bleeding, keep the circulatory system open, and the blood flowing. The occurrence of both surface and bulk interactions adds an additional dimension of complexity. These insights have led to the belief that global overall procedures can inform on the likely behaviour of the system in health and disease. Two sensing procedures: surface plasmon resonance (SPR), which senses surface interactions, and free oscillation rheometry (FOR), which senses interactions within the bulk, have been combined and evaluated. The contribution of blood cells, mainly platelets, to the SPR and FOR signals was explored by simultaneous SPR and FOR measurement during native whole blood coagulation, accelerated via the platelets through addition of SFLLRN peptide and inhibition of platelet aggregation with abciximab (ReoPro®) and of shape change with cytochalasin E. The SPR technique was found to be sensitive to inhibition of blood cell functions such as adhesion to and spreading on surfaces, as well as platelet aggregation. SPR seemed not to be directly sensitive to fibrin polymerisation in coagulating whole blood. The FOR technique detected the coagulation as a bulk phenomenon, i.e. the gelation of the blood due to fibrin formation was detected. The combination of SPR and FOR may therefore be suitable for studies on blood cell functions during coagulation.

Surface plasmon resonance and free oscillation rheometry in combination: a useful approach for studies on haemostasis and interactions between whole blood and artificial surfaces

In haemostatic and biomaterial research biological processes at surfaces and in the bulk phase of the surface-contacting medium are important. The present work demonstrates the usefulness of the combination of surface plasmon resonance (SPR), sensitive to changes in refractive index at surfaces, and free oscillation rheometry (FOR), sensitive to rheological properties of the bulk, for simultaneous real-time measurements on coagulation and fibrinolysis of blood plasma and coagulation of whole blood. SFLLRN stimulated coagulation of native whole blood presented a higher SPR signal with different appearance than plasma coagulation, while the FOR signals corresponding to plasma and whole blood coagulation were similar. This indicated that the SPR technique was more sensitive to cell-surface interactions than to fibrin formation in whole blood during coagulation, while the FOR technique were equally sensitive to coagulation in whole blood and plasma. Spontaneous coagulation of native whole blood in contact with methyl- and hydroxyl-terminated self-assembled monolayers (SAM) on gold and gold surfaces regenerated after coagulation were also studied. The regenerated gold surfaces displayed the shortest coagulation times, although the contact-activation of blood coagulation for these surfaces was low. The methylated and hydroxylated surfaces were comparable in terms of coagulation activation, while the hydroxylated surfaces presented FOR signals that indicated detaching of the coagulum from the surface. The combination of SPR and FOR is well suited for studies of cell– and protein–surface interactions and simultaneous bulk processes. Possible applications are investigations of blood cell defects in patients and monitoring of native whole blood interactions with artificial surfaces.

Using Surface Plasmon Resonance and the Quartz Crystal Microbalance to Monitor in Situ the Interfacial Behavior of Thin Organic Films

We have used a combination of surface plasmon resonance (SPR) and the quartz crystal microbalance (QCM) to monitor in situ the solution-phase adsorption of the perfluoropolyether lubricant Fomblin ...

The interaction between endopolygalacturonase from Fusarium moniliforme and PGIP from Phaseolus vulgaris studied by surface plasmon resonance and mass spectrometry.

A combination of surface plasmon resonance (SPR) and matrix-assisted laser-desorptionionization- time-of-flight mass spectrometry (MALDI-TOF-MS) was used to study the interaction between endopolygalacturonase (PG) from Fusarium moniliforme and a polygalacturonase-inhibiting protein (PGIP) from Phaseolus vulgaris. PG hydrolyses the homogalacturonan of the plant cell wall and is considered an important pathogenicity factor of many fungi. PGIP is a specific inhibitor of fungal PGs and is thought to be involved in plant defence against phytopathogenic fungi. SPR was used either to study the effect of the PG glycosylation on the formation of the complex with PGIP, and as a sensitive affinity capture of an interacting peptide from a mixture of PG fragments obtained by limited proteolysis. Mass spectrometry allowed to characterise the interacting peptide eluted from the sensor surface.

Practical considerations in BIA/MS: optimizing the biosensor–mass spectrometry interface

Biomolecular interaction analysis mass spectrometry (BIA/MS) is a multiplexed analytical technique that utilizes a unique combination of surface plasmon resonance (SPR) and matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the detection and analysis of small amounts of proteins residing in complex biological systems. In order to achieve high sensitivity during BIA/MS, certain experimental parameters and sequences of events need to be optimized and maintained. Immobilized ligand density, flow rate and biosensor control (in SPR-BIA) and matrix choice and application (in MALDI-TOF MS) have significant influence on the final outcome of the BIA/MS analysis and, consequently, need to be optimized and carefully controlled. In addition, chip washing and cutting are essential in converting the SPR-active sensor chips into target surfaces amenable to MALDI-TOF MS. Reviewed here are the prerequisites for successfully interfacing SPR-BIA with MALDI-TOF MS. Copyright © 2000 John Wiley & Sons, Ltd.

Practical considerations in BIA/MS: optimizing the biosensor-mass spectrometry interface.

Biomolecular interaction analysis mass spectrometry (BIA/MS) is a multiplexed analytical technique that utilizes a unique combination of surface plasmon resonance (SPR) and matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the detection and analysis of small amounts of proteins residing in complex biological systems. In order to achieve high sensitivity during BIA/MS, certain experimental parameters and sequences of events need to be optimized and maintained. Immobilized ligand density, flow rate and biosensor control (in SPR-BIA) and matrix choice and application (in MALDI-TOF MS) have significant influence on the final outcome of the BIA/MS analysis and, consequently, need to be optimized and carefully controlled. In addition, chip washing and cutting are essential in converting the SPR-active sensor chips into target surfaces amenable to MALDI-TOF MS. Reviewed here are the prerequisites for successfully interfacing SPR-BIA with MALDI-TOF MS.

Electropolymerization of a phenol-modified peptide for use in receptor–ligand interactions studied by surface plasmon resonance

In this paper, the combination of surface plasmon resonance (SPR) with an electrochemical method for surface modification is presented. The SLP1 sequence of the sodium channel protein of rat cardiac muscle cells was N-terminally modified with an electropolymerizable group and immobilized on a gold-coated glass slide by oxidative polymerization. The resulting peptide-functionalized substrate was incubated with a polyclonal-specific anti-SLP1 serum. Growth of the peptide layer and the immunological reaction between ligand and receptor were detected on-line by SPR. The applicability of this approach for the rapid and selective analysis of receptor–ligand interactions is demonstrated.

Experimental data from a trace metal sensor combining surface plasmon resonance with anodic stripping voltammetry

A technique for sensing metal ions with a combination of surface plasmon resonance and anodic stripping voltammetry is described. Potential enhancements to conventional anodic stripping voltammetry resulting from this technique are discussed. An experimental setup and data showing the simultaneous sensing of 500 nM lead and copper ion are presented and interpreted.

Control of the Specific Adsorption of Proteins onto Gold Surfaces with Poly(L-lysine) Monolayers

Monolayers of the polypeptide poly(L-lysine) (PL) are used to control the specific adsorption of proteins onto gold surfaces. A PL monolayer modified with biotin is electrostatically adsorbed onto a vapor-deposited gold film that has been coated with a self-assembled monolayer of the alkanethiol 11-mercaptoundecanoic acid (MUA). The immobilized biotin moieties act as specific adsorption sites for the protein avidin. Adsorption of the biopolymers onto the gold surface is monitored with a combination of surface plasmon resonance (SPR) and fluorescence measurements. By varying the percent biotinylation of the lysine residues on the PL prior to deposition, the surface coverage of avidin can be controlled to create either full or partial monolayers. The thickness of a full monolayer of avidin is 41 A, as determined by the SPR measurements. At high surface coverages of avidin, an excess of biotin sites is required to overcome steric hindrance. The PL monolayer and any adsorbed avidin can be easily rinsed from the surface with a low or high pH solution. This removal allows for quantitation of the adsorbed molecules by fluorescence measurements in solution rather than on the gold surface. In this manner, fluorescein-labeled PL and avidin are used to determine absolute surface coverages of 4 x 10 14 lysine residues cm -2 for the PL monolayer and 3 x 10 12 avidin molecules cm -2 for the full avidin monolayer. SPR imaging experiments are employed to verify that UV photopatterning of the MUA/PL bilayers can be used to spatially direct the adsorption of avidin onto the gold surface. The polylysine attachment methodology will be beneficial in the fabrication of adsorption biosensors.

Variable Index of Refraction Ultrathin Films Formed from Self-Assembled Zirconium Phosphonate Multilayers: Characterization by Surface Plasmon Resonance Measurements and Polarization/Modulation FT-IR Spectroscopy

Ultrathin (submicrometer) organic films of specified index of refraction are constructed by the sequential deposition of self-assembled zirconium phosphonate (ZP) molecular monolayers that contain two different bisphosphonate ions, 1,10-decanediylbis(phosphonate) (DBP) and 4,4'-azobis[(p-phenylene)methylene]bis(phosphonate) (AZO). By varying the ratio of DBP to AZO monolayers in the ZP multilayer film, the index of refraction can be controlled. A combination of surface plasmon resonance (SPR) measurements and polarization/modulation Fourier transform infrared reflection-absorption spectroscopy (PM/Fr-IRRAS) is used to examine the structure of the ZP multilayers on vapor-deposited gold substrates, and ellipsometric measurements are utilized to determine the index of refraction of the ZP multilayers on transparent substrates. ZP films consisting of 100% DBP and 100% AZO molecules are found to have indices of refraction of 1.51 and 1.64, respectively, at an optical wavelength of 632.8 nm. In both the 100% DBP and the 100% AZO multilayers, an average monolayer thickness of 16 ± 0.5 A is determined from the SPR measurements. The spectroscopic and ellipsometric data indicate that the index of refraction of mixed ZP multilayer films (i.e., films with both DBP and AZO self-assembled monolayers) can be varied systematically between 1.51 and 1.64, but that the average thickness of the self-assembled monolayers is greater in the mixed films than in either of the 100% DBP or 100% AZO multilayers.