Methylation of lysine residues, first shown by Rayment et al., has been extensively employed in the crystallization of biologically relevant proteins. Lysine methylation has been reported to improve hydrophobicity of the biomolecule in solution and thus promote crystallization by increasing conformational rigidity and order. Herein we employ the technique on several peptides (Cecropin A and model peptides AK4 and AK5) to elucidate the effect of methylation of basic resides i.e. Lys, Arg, N-terminus. Specifically, dimethylammonium borane is used as a reducing agent in tandem with formaldehyde in order to add up to two alkyl groups to each basic residue. Information on how ESI-MS charge state distribution (CSD) and molecular dimensions of the gas phase ions, as determined by ion mobility-mass spectrometry (IM-MS), are affected by analyte methylation are reported.

Effect of lysine methylation on charge state distribution and conformational preferences of peptides in the gas phase utilizing ion mobility � mass spectrometry

247th National Meeting (2014)

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