MALDI-TOF-TOF-Mass Spectrometer for mass spectrometric imaging

• Subject Area: Medicine
• Term: Funded in 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 426788273

The matrix-assisted-laser-desorption-ionization (MALDI) tandem-time-of-flight mass spectrometer (TOF-TOF-MS), which is applied for, will be used for mass spectrometric imaging of tissue sections and for determination of molecular weights of biomolecules, such as glycans, lipids, nucleotides, peptides and proteins. The MALDI-TOF-TOF-MS will supplement existing electro-spray-ionisation (ESI) high-resolution tandem mass spectrometers, since the desorption- and ionisation mechanisms are significantly different, and thus will be used, if expected signals of analytes are not detectable with ESI. With the TOF-TOF mass analyzer fragment spectra of analyte ions will be recorded, for enabling their identification. This function is also very important for mass spectrometric imaging. The later will be used for analysis of tissue-micro arrays, prepared by the Pathology, for screening for cancer markers, for analysis of diseased tissues, as an addition to existing histological methods and by the Anatomy for analysis of morphologies of tissues from experimental models. The Core-Facility "Mass Spectrometric Proteomics" of the University Medical Center Hamburg-Eppendorf, will use the MALDI-TOF-TOF-MS, beside the above mentioned determination of molecular weights of intact ions and their fragments, for different forms of proteomics, such as bottom-up proteomics (digestion of protein extracts, separation of resulting peptides, collection of the fractions on MALDI targets, analysis of the peptides and their fragments with the MALDI-TOF-TOF-MS, bioinformatic processing and interpretation of the mass spectrometric data for identification of the proteins), as an optional addition to the analysis of tryptic peptides by existing liquid chromatography systems coupled via ESI to high resolution tandem mass spectrometers. The very high speed of the MALDI-TOF-TOF-MS will allow a new form of relative quantitative proteomics of proteoforms, by applying metabolic labeling of proteins with stable isotopes. Light and heavy proteins of samples A and B will be mixed, separated by two-dimensional electrophoresis, the whole gel will be cut into approximately 1000 squares, proteins in the gel squares digested, resulting peptides desalted, analyzed by MALDI-TOF-TOF-MS and from the resulting data the identities and quantities determined by subsequent application of the bioinformatic tools. By this approach, system related changes in cells on the level of proteoforms will be detected. The MALDI-TOF-TOF-MS will be also applied for top-down analysis of intact proteins, especially for determination of C-terminal and N-terminal amino acid sequences (replacement of an Edman sequencer). This kind of analysis is e.g. important for many groups in Hamburg aiming x-ray analysis of crystalized proteins, as well as for the European graduate school "Analytics for Biologics – A4B", focusing on the analysis of proteoforms of therapeutic proteins.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: MALDI-TOF-TOF-Massenspektrometer für massenspektrometrisches Imaging
• Instrumentation Group: 1700 Massenspektrometer
• Applicant Institution: Universität Hamburg
• Leader: Professor Dr. Hartmut Schlüter
• Cooperation Partner: Professor Dr. Pengyuan Yang