Molecular masses of Up4U fragments obtained by MALDI-TOF-TOF mass spectrometry (Figure 1.B).

The first column shows the fragment masses measured by MALDI-TOF-TOF mass spectrometry; second column shows the fragments mass of Up4U isolated from the endothelial secretome; the third column the fragments mass of Up4U isolated from plasma; the fourth column shows the fragment masses calculated from their respective structures; the fifth column shows the fragments masses of synthesised Up4U. M+ = protonated parent ion; Ú = uracil; U = uridine; p = phosphate group, e.g. Up3 = UTP; w/o = without.