title: MALDI imaging and profiling MS of higher mass proteins from tissue.
abstract: MALDI imaging and profiling mass spectrometry of proteins typically leads to the detection of a large number of peptides and small proteins but is much less successful for larger proteins: most ion signals correspond to proteins of m/z < 25,000. This is a severe limitation as many proteins, including cytokines, growth factors, enzymes, and receptors have molecular weights exceeding 25 kDa. The detector technology typically used for protein imaging, a microchannel plate, is not well suited to the detection of high m/z ions and is prone to detector saturation when analyzing complex mixtures. Here we report increased sensitivity for higher mass proteins by using the CovalX high mass HM1 detector (Zurich, Switzerland), which has been specifically designed for the detection of high mass ions and which is much less prone to detector saturation. The results demonstrate that a range of different sample preparation strategies enable higher mass proteins to be analyzed if the detector technology maintains high detection efficiency throughout the mass range. The detector enables proteins up to 70 kDa to be imaged, and proteins up to 110 kDa to be detected, directly from tissue, and indicates new directions by which the mass range amenable to MALDI imaging MS and MALDI profiling MS may be extended.
authors.affiliation: Biomolecular Mass Spectrometry Unit, Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Alexandra
authors.initials: A
authors.lastname: van Remoortere
authors.forename: René J M
authors.initials: RJ
authors.lastname: van Zeijl
authors.forename: Nico
authors.initials: N
authors.lastname: van den Oever
authors.forename: Julien
authors.initials: J
authors.lastname: Franck
authors.forename: Rémi
authors.initials: R
authors.lastname: Longuespée
authors.forename: Maxence
authors.initials: M
authors.lastname: Wisztorski
authors.forename: Michel
authors.initials: M
authors.lastname: Salzet
authors.forename: André M
authors.initials: AM
authors.lastname: Deelder
authors.forename: Isabelle
authors.initials: I
authors.lastname: Fournier
authors.forename: Liam A
authors.initials: LA
authors.lastname: McDonnell
mesh_terms: D000097:Acetonitriles; D000818:Animals; D001923:Brain Chemistry; D003373:Coumaric Acids; D003952:Diagnostic Imaging / Q000379:methods*; D006651:Histocytochemistry / Q000379:methods*; D016591:Histocytological Preparation Techniques; D008297:Male; D051379:Mice; D008970:Molecular Weight; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: D000097:Acetonitriles; D003373:Coumaric Acids; D011506:Proteins; C073734:sinapinic acid; C032159:acetonitrile