Institutes for pharmaceutical chemistry -
Prof. Dr. Michael Karas

Expertise

Identification and characterization of proteins expressed in cells or cell compartments
Mass spectrometry (MALDI and ESI) of intact proteins, peptides, oligosaccharides, drugs and metabolites
Method development for investigation of membrane proteins and membrane protein complexes
In-vitro assay for transcription/translation for search for new inhibitors of the bacterial protein synthesis (antibiotics)
Method development in drug analysis
Liquid chromatography
Gel electrophoresis

Resources and Abilities

1D/2D-Gelelectrophoresis
Blue-native Gel electrophoresis
MALDI TOF Mass spectrometry
MALDI TOF-TOF Mass spectrometry
Nano-ESI-MS
HPLC-ESI-MS/MS
µ-bore, capillary- and nano-HPLC
TAP Tandem affinity purification for analysis of functional multi-protein complexes

Publications

F. Hillenkamp, M. Karas, R.C. Beavis, B.T. Chait, Matrix- Assisted Laser Desorption/Ionization Mass Spectrometry of Biopolymers. Anal. Chem. 63 (1991) 1193A -1203A.
U. Bahr, M. Karas, Differentiation of "Isobaric" Peptides and Human Milk Oligosaccharides by Exact Mass Measurements Using ESI-orthogonal TOF Analysis. Rapid Commun. Mass Spectrom. 13 (1999) 1052-1058.
B. Finke, B. Stahl, A. Pfenninger, M. Karas, H. Daniel, G. Sawatzki, Analysis of High-Molecular-Weight Oligosaccharides from Human Milk by Liquid Chromatography and MALDI-MS. Anal. Chem. 71 (1999) 3755-3762.
M.Abdel Tawab, U. Bahr, B. Danieli, S. Gebhardt, M. Karas, S. Riva, M. Schubert-Zsilavecz, Electrospray Mass Spectrometry with Consecutive Fragmentation Steps (ES-MSn) as a Tool for Rapid and Sensitive Analysis of Ginsenosides and their Galactosyl Derivatives. Helv. Chim. Acta 83 (2000) 739-747.
A. Schmidt, U. Bahr, M. Karas, The Influence of Pressure in the First Pumping Stage on Analyte Desolvation and Fragmentation in Nano-ESI MS. Anal. Chem. 73 (2001) 6040-6046.
A. Schmidt, M. Karas, The influence of Electrostatic Interactions on the Detection of Heme-Globin Complexes in ESI-MS J. Am. Soc. Mass Spectrom. 12 (2001) 1092-1098.
A. Pfenninger, M. Karas, B. Finke, B. Stahl, Structural Analysis of Underivatized Neutral Human-Milk Oligosaccharides in the Negative Ion Mode by Nano-Electrospray MSn (Part 1 : Methodology). J. Am. Soc. Mass Spectrom. 13 (2002) 1331-1340.
A. Pfenninger, M. Karas, B. Finke, B. Stahl, Structural Analysis of Underivatized Neutral Human-Milk Oligosaccharides in the Negative Ion Mode by Nano-Electrospray MSn (Part 2 : Application to Isomeric Mixtures.) J. Am. Soc. Mass Spectrom. 13 (2002) 1341-48.
A. Schmidt, T. Dülks, M. Karas, Effect of different solution flow rate on analyte ion signals in nano-ESI MS, or : When does ESI turn to Nano-ESI. J. Am. Soc. Mass Spectrom. 14 (2003) 492-500.
R. Krüger, M. Karas, Ion Formation in MALDI: The Cluster Ionization Mechanism. Chem. Rev. 103 (2003) 427-439.
C. Corvey, T. Stein, S. Düsterhus, M. Karas, K.-D. Entian, Activation of subtilin precursors by Bacillus subtilis extracellular serine proteases subtilisin (AprE), WprA, and Vpr. Biochem. Biophys. Res. Commun. 304 (2003) 48-54.
K. Ekroos, C. S. Ejsing, U. Bahr, M. Karas, K. Simons, A. Shevchenko. Charting molecular composition of phosphatidylcholines by fatty acid scanning and ion trap MS3 fragmentation. J. Lipid Res. 44 (2003) 2181-2192.
J.-H. Keller, M. Karas, W.E. Müller, D.A. Volmer, G.P. Eckert, M. Abdel-Tawab, H.H. Blume, T. Dingermann, M. Schubert-Zsilavecz, Determination of Hyperforin in Mouse Brain by Rapid High Performance Liquid chromatography/Tandem Mass Spectrometry. Anal. Chem. 75 (2003) 6084-6088.