title: Quantification of peptides for the monitoring of protease-catalyzed reactions by matrix-assisted laser desorption/ionization mass spectrometry using ionic liquid matrixes.
abstract: Ionic liquid matrixes (ILM) have been shown to allow very homogeneous sample preparations, facilitating relative quantifications using internal standards in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). In the present work, the ability to perform quantifications of peptides without using internal standards in these matrixes was investigated. Linear correlations between peptide amount and signal intensities could be observed when increased molar matrix-to-analyte ratios were applied. The dynamic range of linearity was approximately 1 order of magnitude. The method was applied successfully to monitor the time-dependent evolution of substrates and products in trypsin-catalyzed digests of single peptides and peptide mixtures. Thus, ionic liquid matrixes allow quantitative MALDI-MS without the need for internal standards, making the method a suitable tool for the fast screening of new enzymes or the search for substrates or inhibitors.
authors.affiliation: Technische Biochemie, Universität des Saarlandes, 66123 Saarbrücken, Germany. a.tholey@mx.uni-saarland.de
authors.forename: Andreas
authors.initials: A
authors.lastname: Tholey
authors.forename: Masoud
authors.initials: M
authors.lastname: Zabet-Moghaddam
authors.forename: Elmar
authors.initials: E
authors.lastname: Heinzle
mesh_terms: D002853:Chromatography, Liquid; D007834:Lasers; D010446:Peptide Fragments / Q000032:analysis*; D011506:Proteins / Q000032:analysis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014357:Trypsin / Q000494:pharmacology*
chemical_list: D010446:Peptide Fragments; D011506:Proteins; D014357:Trypsin