Voyager detm str maldi tof mass spectrometer

Details of the method used for the enzymatic digestion of gels and their MALDI-TOF-MS analysis can be found in our previous publication^{9 (link)}. Concisely, protein spots of interest were digested using trypsin solution and the digested peptides were then purified by using C-18 Zip tips according to the manufacturer’s protocol. The C18 tips with the absorbed peptides were eluted with matrix solution (10 mg/mL α-cyano-4-hydroxycinnamic acid (CHCA)) onto a MALDI target and analyzed using a Voyager-DE^TM STR MALDI-TOF mass spectrometer (Applied Biosystems (AB), Foster City, CA, USA). Proteins were identified by peptide mass fingerprinting utilizing the Mascot v2.0 software (http://www.matrixscience.com) from Matrix Science (Boston, MA, USA) and as peptide search engines the Mass Spectrometry protein sequence DataBase (MSDB) and the National Center for Biotechnology Information (NCBInr) protein databases. Probability-based molecular weight search (MOWSE) scores were estimated by comparing the search result with an estimated random match population and was reported as −10*LOG₁₀(P), where P is the absolute probability. Scores greater than 65 were considered statistically significant (p < 0.05).

Molecular mass identification of rHNTX-IV was performed on a Voyager-DE^TM STR MALDI-TOF mass spectrometer (Applied Biosystems, Voyager-DE STR Biospectometry workstation). Ionization was achieved by irradiation with a nitrogen laser (337 nm), with a 20-kV acceleration voltage. α-Cyano-4-hydroxy-cinnamic acid was used as the matrix.