Table 4.

The m/z values for detected fragment y ions for the peptide at 789.898 selected for HCD fragmentation. The observed value is given, along with the calculated values for each fragment according to the two sequences (T. rex and Struthio) under question, emphasizing the ability to distinguish between an oxidated proline and isoleucine/leucine residue in the carboxy-terminal region of the peptide.

Frag ionobservedP(Oxidation)- LppmL-P(Oxidation)ppmppm calc
y4432.2565432.220175
y5529.3055529.30937.2529.272961.669
y6586.3375586.330711.6586.294473.562
y7657.369657.36781.8657.33155755
y8754.4185754.42062.8754.384245.548
y9811.4386811.44214.3811.405740.545
y10910.5069910.51054910.47413640
y11981.5446981.54763.1981.51123437
y121038.56461038.56914.31038.532730.735
y131125.59521125.60115.21125.564727.132
y141254.64431254.64370.51254.607329.529
y151311.65821311.66525.31311.628822.428
y161424.70631424.71284.61408.6815