Derivatisation of peptides with osmium tetroxide, 2,2′-bipyridine: capillary electrophoretic and MALDI–TOF mass spectrometric study

• Published in: Analytica chimica acta Vol. 515; no. 2; pp. 261 - 269
• Main Authors: Šedo, O, Billová, S, Peña-Méndez, E.M, Paleček, E, Havel, J
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 12.07.2004; Elsevier
• Subjects: 2,2′-Bipyridine; Analytical biochemistry: general aspects, technics, instrumentation; Analytical chemistry; Analytical, structural and metabolic biochemistry; Biological and medical sciences; Chemistry; Chromatographic methods and physical methods associated with chromatography; CZE; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; MALDI–TOF MS; Osmium tetroxide; Other chromatographic methods; Peptide derivatisation; PSD; Spectrometric and optical methods; PSD; 2,2′-Bipyridine; MALDI–TOF MS; Osmium tetroxide; Peptide derivatisation; CZE; Complexation; Cysteine; Zone electrophoresis; Peptides; Capillary electrophoresis; Methionine; 2,2'-Bipyridine; Bipyridines; Matrix assisted laser desorption ionization; Derivatization; Protein; MALDI-TOF MS; Chemical modification; Time of flight method; Oxidation; Aqueous solution; Mass spectrometry; Ultraviolet visible spectrometry
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2004.03.066

Site-specific chemical modification is a useful technology in characterisation of proteins, but the number of chemical probes of the protein structure reacting with proteins under mild conditions in aqueous solutions is rather limited. Here we studied the reaction of osmium tetroxide, 2,2′-bipyridine (Os,bipy) with several peptides using capillary zone electrophoresis (CZE) and matrix-assisted laser desorption-ionisation–time-of-flight mass spectrometry (MALDI–TOF MS). Both techniques showed formation of a stable complex of Os,bipy with tryptophan residues. In CZE peaks with different migration times and UV-Vis spectra were observed. MALDI–TOF MS showed the formation of a product with characteristic isotopic pattern corresponding to the presence of osmium atom. Oxidation of cysteine and methionine side chains to cysteic acid and methionine sulfone by Os,bipy was detected by CZE and confirmed by MALDI–TOF and post-source decay (PSD) mass spectra. PSD showed specific shifts of molecular weights of the peptides and their fragments after the derivatisation. We believe that Os,bipy may become a useful agent in the characterisation of proteins.