Ultraflex maldi tof instrument

For protein identification by matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) MS, silver stained [45 ] or Instant Blue-stained (Expedeon) spots were manually excised from the 2-dimensional electrophoresis gel and digested with trypsin as described previously [47 (link)]. Tryptic peptide mixtures were cleaned up using Proxeon Stage Tips and spotted on the MALDI target using α-cyanocinnamic acid as matrix. The peptide masses were analysed using an Ultraflex MALDI-TOF instrument (Bruker-Daltonics) and used to query the NCBI database (28 November 2009 release) by the Mascot search engine. Search parameters used were carbidomethylation of cysteine residues and allowing oxidation of methionine. Fragment mass error tolerance was 0.2 Da and up to one missed cleavage was allowed.

The mass/charge of pure isolated (cleaved) CM4 and Synoeca peptides was verified by matrix-assisted laser desorption/ionization with time of flight (MALDI-TOF) on an Ultra-Flex MALDI-TOF instrument (Bruker Daltonics GmbH, Bremen, Germany) equipped with a 337 nm nitrogen laser and using sinapic acid as the matrix (≥99.5%). Sample preparation was performed as previously described [55 (link)].