Lao, Ying2015-01-132015-01-1320122014J. Reimer, V. Spicer, O.V. Krokhin, J Chromatogr A 1256 (2012) 160Y.W. Lao, K. Mackenzie, W. Vincent, O.V. Krokhin, Journal of Separation Science 37 (2014), 1788-1796.http://hdl.handle.net/1993/30202The thesis consists of two parts targeting the characterization of chromatographic behavior of linear tryptic and cyclic peptides containing oxidized methionine (Met) in reversed-phased chromatography. The retention order of methionine-containing peptide analogues was observed to be the same in both studies: Met oxide < Met dioxide < Met. For linear tryptic peptides, the magnitude of the retention time shift may vary dramatically: from –9 % to +0.36 % acetonitrile. Particularly, large negative retention time shifts are found mostly associated with methionine being in the hydrophobic face of an amphipathic helix. Contrary to previously reported observations, I demonstrate for the first time that methionine oxidation may increase peptide hydrophobicity, this occurs only when methionine is in the N3 position of the N-capping stabilization motif preceding an amphipathic helix. In the second study, the effect of peak splitting was observed for some Met oxide-containing cyclolinopeptides, which most likely appear due to diastereomerization.engMethionine OxidationReversed-phase chromatographytryptic peptidescyclolinopeptidesmaster thesis