Seldi
The
possibilities of the SELDI-TOF platform
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| The SELDI-TOF platform is ultimately suitable for profiling experiments to identify biomarkers. Profiling of specific biomarkers or clusters of biomarkers in samples of different origin using the SELDI-ProteinChip technology platform can be performed in two different ways. The first and most frequently performed technique is the expression difference mapping (EDM) using chemically prepared ProteinChips with standard chemical surfaces. These Surfaces are presented in figure 3. Seperation depends on the chemical characterics of the molecules and the binding characteristics of the used ProteinChip. Only a subset of proteins will bind and therefore different binding conditions and different ProteinChips have to be used to identify the full spectrum of proteins. |
| In case the study is directed towards specific interactions between several molecules, interaction difference mapping (IDM) analyses is also suitable. In this approach, first the known ligands (for example antibodies, antibody capturing proteins) will be covalently coupled to the preactivated ProteinChip surfaces (figure 3) to obtain the Biological ProteinChips. Next, the biological surfaces will be incubated with the samples. |
| After profiling for specific biomarkers it might be useful to identify the biomarker. The SELDI-TOF is not developed to identify proteins but this might be a future application. Several possibilities exist, such as on ProteinChip tryptic digestion or coupling via interface to a more sophisticated high-resolution mass spectrometer. In Nijmegen the coupling to a high resolution mass spectrometer is not possible yet. |
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| Figure 5: The ProteinChip array surfaces available. Two different kind of ProteinChips are variable. The first line represents the ProteinChips with chemical surfaces. The second line deals with biological surfaces to which different ligands can be coupled covalently. |
