HyperISGylation of Old World Monkey ISG15 in Human Cells

Pattyn, Els; Verhee, Annick; Uyttendaele, Isabel; Piessevaux, Julie; Timmerman, Evy; Gevaert, Kris; Vandekerckhove, Joël; Peelman, Frank; Tavernier, Jan

The generated peptide fragmentation spectra were searched using the MASCOT database search engine (http://www. matrixscience.com) in the SwissProt database (taxonomy was set to human). The following MASCOT parameters were set. The enzyme setting was trypsin with a maximum of 1 missed cleavage allowed. Variable amino acid modifications that were allowed are acetylation (N-term), carbamylation (Lys and N-term), deamidation (Asn and Gln), formation of pyroglutamate (N-terminal Gln), oxidation of Met to its sulfoxides and propionamide modification of Cys. Allowed peptide and fragment ion mass tolerance were 0.3 Da (Q-TOF) or 0.5 Da (ion trap). MASCOT's instrument setting was ''ESI-QUAD-TOF'' (Q-TOF) or ''ESI-TRAP'' (ion trap) for calculating theoretical peptide fragmentation spectra.