Analysis of hydroxyproline modifications on collagen I alpha chain I.

Two tryptic peptides of collagen 1 alpha chain 1 (COL1A1) with highly-confident hydroxyproline site localizations due to specific and comprehensive fragmentation. A) Representative spectrum displaying the ion series for GDTGA704PoxGA707PoxGSQGA713PoxGLQGM719PoxGER. Fragmentation series provides site localization evidence to confirm modified prolines based on direct and indirect ion evidence including the y4, y5, y10, y16, and y19 ions. B) Extracted ion chromatograms (XIC) of GDTGA704PoxGA707PoxGSQGA713PoxGLQGM719PoxGER precursor ion (m/z = 743.67, z = 3+) on the left and fragment ions (y10, y4, and y19) on the right. C) Similar representative spectrum displaying the fragment ions for the singly modified GLTGS533PoxGSPGPDGK. Direct ion evidence for the modified peptide can be attributed to the y4, y6, and y9 ions. D) XIC of GLTGS 533PoxGSPGPDGK precursor ion (m/z = 621.80 and z = 2+) on the left and fragment ions (y9, y6, and y10) on the right.