|Reference : In situ protein identification in imaging mass spectrometry|
|Scientific conferences in universities or research centers : Scientific conference in universities or research centers|
|Life sciences : Biochemistry, biophysics & molecular biology|
|In situ protein identification in imaging mass spectrometry|
|Calligaris, David [Université de Liège - ULg > Département de chimie (sciences) > GIGA-R : Laboratoire de spectrométrie de masse (L.S.M.) >]|
|Debois, Delphine [Université de Liège - ULg > Département de chimie (sciences) > GIGA-R : Laboratoire de spectrométrie de masse (L.S.M.) >]|
|De Pauw, Edwin [Université de Liège - ULg > Département de chimie (sciences) > GIGA-R : Laboratoire de spectrométrie de masse (L.S.M.) >]|
|04 Mai 2012|
|Groupe interdisciplinaire de génoprotéomique appliquée|
|[en] Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) is an emerging tool for clinical research. MALDI MSI can be used to elucidate the relative abundance and spatial localization of peptides and proteins throughout a tissue section. For this, a matrix is applied on the tissue in either a spotted array or a homogenous coating. Acquisition of mass spectra is then carried out by performing a raster with a laser across the tissue section in a defined pattern. The spectra acquired from each position on the tissue section contain molecular weight and intensity information representative of the biomolecules at that position. One can plot the intensity of any measured ion as a function of individual pixel locations to generate m/z specific images. But, if protein desorption/ionization and subsequent MS analyses provides a measurement of molecular weight, no protein identification is performed. To achieve this, several methods have been developed.
In this talk, I will first present the methods inspired by classical proteomics techniques that are regularly used to identify proteins. Bottom-up and top-down approaches have been used directly from a tissue slice, leading to the identification of some of the most abundant proteins present within the tissue slice. Then, I will present the new developments led in our lab for imaging and especially for in situ protein identification. The first example will deal with the exceptional features of FT-ICR mass spectrometry for in-source decay (ISD)-based protein identification. The benefit of mass accuracy and high mass resolution allow unequivocal assignment of ISD fragments of proteins, in the low mass range (m/z between 400 and 900), whether from pure solutions or from tissue slices. The next example is the use of a matrix “cleaning” software that reduce/remove matrix peaks thus facilitating ISD spectra analyses. Finally, proteins identification by localization and MALDI-ISD profile matching will also be a really simplistic and interesting method that will complement the immunohistological techniques commonly used to validate expression of known biomarkers within diseased tissues.
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