Mass spectrometric characterization of human skin elastin peptides produced by proteolytic digestion with pepsin and thermitase

This study investigated peptides resulting from the digestion of human skin elastin with pepsin and thermitase. Characterization of the peptides was performed using two complementary mass spectrometric techniques; LC/ESI-ion trap and nano-ESI-qTOF MS. 155 different peptides were identified using a combined database based and de novo sequencing approach resulting in a total sequence coverage of 65.4% calculated on the basis of the precursor tropoelastin (accession number A32707). A potential hydroxylation was found in 29% of the recovered prolines. Furthermore, the absence of amino acids expressed by exon 26A could be confirmed. However, contrary to earlier studies, amino acids expressed by exon 22 seem to exist.