The possibilities of MALDI-TOF mass spectrometric analysis of new neuro-protective peptide [G14]-humanin (HNG) and similar compounds are studied with the aim of finding optimal conditions for the determination of these peptides. Acidification and washing of HNG samples using 5% (v/v) formic acid is necessary to reach a detection limit similar to other peptides. The sensitivity of HNG determination is decreased in the oxidative environment as the peptide yields oxidation of methionine and cysteine forming several species, including a disulfide dimer. During Post-source Decay (PSD) it was found that intense cleavage between Asp and Leu in HNG reduces the possibility of detecting other fragments. Better sequence coverage is gained from shorter humaninlike peptides.
[G14]-humanin; humanin derivatives; MALDI-TOF MS; PSD; peptide oxidation
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