PAS‐cal: A repetitive peptide sequence calibration standard for MALDI mass spectrometry |
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| Authors: | Stefan K Maier Ksenia Bashkueva Christoph Rösli Arne Skerra Bernhard Kuster |
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| Institution: | 1. Chair for Proteomics and Bioanalytics, Technische Universit?t München, , Freising, Germany;2. Institute of Pathology, Research Unit Analytical Pathology, Helmholtz Zentrum München, , Neuherberg, Germany;3. Munich Center for Integrated Protein Science, CIPS‐M, , Munich, Germany;4. HI‐STEM gGmbH, German Cancer Research Center DKFZ, , Heidelberg, Germany;5. Junior Research Group Biomarker Discovery, German Cancer Research Center, , Heidelberg, Germany;6. Lehrstuhl für Biologische Chemie, Technische Universit?t München, , Freising‐Weihenstephan, Germany |
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| Abstract: | Mass spectrometers equipped with matrix‐assisted laser desorption/ionization (MALDI‐MS) require frequent multipoint calibration to obtain good mass accuracy over a wide mass range and across large numbers of samples. In this study, we introduce a new synthetic peptide mass calibration standard termed PAS‐cal tailored for MALDI‐MS based bottom‐up proteomics. This standard consists of 30 peptides between 8 and 37 amino acids long and each constructed to contain repetitive sequences of Pro, Ala and Ser as well as one C‐terminal arginine residue. MALDI spectra thus cover a mass range between 750 and 3200 m/z in MS mode and between 100 and 3200 m/z in MS/MS mode. Our results show that multipoint calibration of MS spectra using PAS‐cal peptides compares well to current commercial reagents for protein identification by PMF. Calibration of tandem mass spectra from LC‐MALDI experiments using the longest peptide, PAS‐cal37, resulted in smaller fragment ion mass errors, more matching fragment ions and more protein and peptide identifications compared to commercial standards, making the PAS‐cal standard generically useful for bottom‐up proteomics. |
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| Keywords: | Calibration LC‐MALDI MALDI‐TOF‐MS PMF Protein identification Technology |
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