European Journal of Mass Spectrometry - Abstract of Copper-induced oligomerization of peptides: a model study

Gitta Schlosser,^a Raluca Stefanescu,^b Michael Przybylski,^b Manuela Murariu,^c Ferenc Hudecz^a and Gabi Drochioiu^d,*
^aResearch Group of Peptide Chemistry, Hungarian Academy of Sciences, Eötvös L. University, Budapest, Hungary and Organic Chemistry Department, Eötvös L. University, Budapest, Hungary
^bLaboratory of Analytical Chemistry, Department of Chemistry, University of Konstanz, Konstanz, Germany
^cPetru Poni Institute of Macromolecular Chemistry, 41 A Aleea Gr. Ghica Voda, Iasi, 700487, Romania
^dFaculty of Chemistry, Al. I. Cuza University of Iasi, 11 Carol I, Iasi 700506, Romania. E-mail: gabidr@uaic.ro

In this work, copper-binding of the tetraglycine peptide (Gly–Gly–Gly–Gly) was studied by electrospray ionization mass spectrometry. Experiments were performed under alkaline conditions, in the presence of ethanolamine (pH 10.95). We observed that the presence of copper(II) ions induces the aggregation of the peptide and the formation of copper- bound complexes with higher molecular mass is favored, such as the oligomer complexes [3M+2Cu–3H]⁺ and [4M+3Cu–5H]⁺. At 1:1 peptide–copper(II) ion ratio, the singly charged [3M+2Cu–3H]⁺ oligomer complex is the base peak in the mass spectrum. Metal ion-induced oligomerization of neurotoxic peptides is well known in the literature; however, there are very few examples in which such oligomerization was directly observed by mass spectrometry. Our results show that application of short peptides can be useful to study the mechanism of metal ion binding and metal ion-induced oligomerization of peptides.