Mass spectrometric identification of a stable catalytic cysteinesulfinic acid residue in an enzymatically active chemically modified glucoamylase mutant

Ekaterina Mirgorodskaya, Henri-Pierre Fierobe, Birte Svensson, Peter Roepsdorff

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Mass spectrometric identification of cysteinsulfinic acid resulting in restoration of activity of chemically modified Glu400 Cys catalytic-base glucoamylase (GA) mutants is described. This oxidation unexpectedly occurred during attempts to carboxyalkylate the Cys400 GA mutant using three different alkylation reagents. However, mass spectrometric peptide mapping did not show the presence of carboxyalkylation of the Cys400 residue but suggested an oxidation to cysteinsulfinic acid based on the observed mass increment. The presence of cysteinsulfinic acid was confirmed by employing matrix-assisted laser desorption/ionization mass spectrometry combined with post-source decay analysis. Furthermore, strong enhancement of metastable fragmentation was observed for peptides containing oxidized Cys in comparison with non-oxidized peptide. Copyright 1999 John Wiley & Sons, Ltd.
Original languageEnglish
JournalJournal of Mass Spectroscopy
Volume34
Pages (from-to)952-957
Publication statusPublished - 1999
Externally publishedYes

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