two lines of evidence indicate that dihydroxyproline does not arise from the further hydroxylation of peptidyl hydroxyproline : first , there was a lag of several minutes between the incorporation of [ ( 14 ) c ] proline into protein and the appearance therein of [ ( 14 ) c ] hydroxyproline but no such lag for the appearance of dihydroxyproline .
C0033382
proline
C0020388
hydroxyproline