Molecular scanner

Figure 6. Mass spectrometry imaging of a capture membrane processed with molecular scanner on a mouse brain (CPu = caudate putamen (striatum) Ml = primary motor cortex VIM = primary visual cortex, monocular region).

Bienvenut, W.V., Sanchez, J.-C., Karmime, A., Rouge, V., Rose, K., Binz, P.A. and Hochstrasser, D.F. (1999) Toward a clinical molecular scanner forproteome research Parallel protein chemical processing before and during werstem blot. Anal. Chem. 71, 4800 807. 

Interpretation of results obtained with the molecular scanner. 250 pg of E. coli were separated on a mini-2DE on a narrow range pi gradient (5-5.5). The gel was submitted to DPD (full in-gel digestion followed by a through trypsin digestion). 

The purpose of the molecular scanner is for the identification of proteins that were separated with a 2-DE gel. Therefore, for each scan point, the lists of peptide masses are submitted to the peptide mass fingerprint identification program Smartldent [51], which searches the protein sequence database SWISS-PROT and returns a list of matching proteins and their score. 

Peak lists and identification results are then written into a text file. The 2-DE gel analysis tool Melanie [148] can read this file and allows loading the molecular scanner data for visualisation. It allows selecting scan points and viewing the identification results and spectra of these points. 

An important point in criteria 1) and 2) is that they take account of spatial correlation and distribution of the data. This allows an improvement in the results to a much greater extent than if only localised information was available. We beheve that this is one of the strongest features of the molecular scanner. 

In combination with a MALDI-TOF/TOF spectrometer [190] the molecular scanner approach could be used to identify proteins with peptide fragmentation data. We believe that this is a very promising approach for future development. 

Figure 8.8. Descriptive scheme of the molecular scanner approach in imaging mass spectrometry. Reprinted from reference 35 with permission from Elsevier (See color insert).

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