Electrochemical oxidation and cleavage peptides in bioanalysis. Mechanistic aspects & method development

PhD ceremony: Mr. J. Roeser, 16.15 uur, Academiegebouw, Broerstraat 5, Groningen

Dissertation: Electrochemical oxidation and cleavage peptides in bioanalysis. Mechanistic aspects & method development

Promotor(s): prof. R.P.H. Bischoff

Faculty: Mathematics and Natural Sciences

Electrochemistry combined with mass spectrometry (EC-MS) is a fairly recent technique which has the potential of modifying and characterizing molecules in an integrated analytical fashion. Electrochemistry allows fast product formation under mild, reagent-free conditions whereas mass spectrometry provides sensitive detection and detailed structural information and can be directly coupled to an electrochemical cell for time-resolved analysis of potentially reactive and unstable compounds. The present thesis focuses on the use of EC-MS to study the electrochemical oxidation and cleavage of peptides and proteins. EC has been shown to mediate cleavage reactions C-terminal to tyrosine (Tyr) and tryptophan (Trp) within peptides and proteins. Electrochemical oxidation of peptides and the subsequent chemical reactions are investigated and a detailed insight is given on the influence of reaction conditions on the generated oxidation and cleavage products. A chemical labeling approach specifically targeting electrochemically cleaved peptides is introduced and opens the possibility of developing new strategies to specifically target cleaved peptides among potentially complex mixtures of oxidation products. We finally describe the advantages of boron-doped diamond (BDD) electrodes over glassy carbon electrodes in terms of lower adsorption, wider potential window and the possibility of regenerating the electrode surface for extended and repeatable reactions. The lower adsorption allows the cleavage of larger peptides and opens the way to introducing this approach in regular proteomics workflows.