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Updated: Jun 21, 2026
A New Approach for the Comparative Analysis of Multiprotein Complexes Based on 15N Metabolic Labeling and Quantitative Mass Spectrometry
Published on: March 13, 2014
Analytical approach for characterization of cadmium-induced thiol peptides--a case study using Chlamydomonas
Anja Bräutigam1, Dirk Schaumlöffel, Gerd-Joachim Krauss
1Martin-Luther-Universität Halle-Wittenberg, Institut für Biochemie und Biotechnologie, Okologische und Pflanzen-Biochemie, Kurt-Mothes-Strasse 3, 06120, Halle (Saale), Germany. anja.braeutigam@biochemtech.uni-halle.de
Abstract:
Phytochelatins (PC) were described earlier to play a role in metal detoxification in Chlamydomonas reinhardtii but were not clearly identified. The focus of this case study was to identify PC synthesized by C. reinhardtii exposed to Cd. Only low intracellular concentrations of cadmium (85 nmol g(-1) fresh weight) were sufficient to cause significant changes in thiol peptide pools. Thus, results showed a progressive decline of the glutathione content, accompanied by an induction of phytochelatins. Not only canonic phytochelatins but for the first time also the iso-phytochelatins CysPC(n) and PC(2)Ala were identified in this unicellular green alga using electrospray ionization quadrupole time-of-flight tandem mass spectrometry. Additionally, CysPC(n)desGly, PC(n)desGly, CysPC(n)Glu, and PC(2)Glu were found throughout MS analysis. Also, low abundant PCs could be detected due to the high sample preconcentration combined with little sample amounts (0.3 microL min(-1)) necessary for electrospray. Identified PCs had a maximum number of 5 gamma-glutamyl cysteine (gamma-GluCys) units. Thiol peptides of higher molecular masses suggesting PC(n) with n > 5 could be identified as intermolecular oxidation products of smaller PCs. Thiols may easily be oxidized. Therefore, PCs were reduced prior to MS analysis. Dithiothreitol and tris(2-carboxyethyl) phosphine were compared concerning their reduction effort.
