for studies on the biosynthesis of procollagen , the cells were incubated with [ ( 14 ) c ] proline in a medium supplemented with ascorbic acid and beta-aminopropionitrile , and the synthesis of nondialyzable [ ( 14 ) c ] hydroxyproline , in relation to dna or cell protein , was taken as an index of procollagen formation .
C0033382
proline
C0020388
hydroxyproline