BIOSYNTHESIS OF COLLAGEN [C-14]HYDROXYPROLINE AND [C-14]-HYDROXYLYSINE DURING MATURATION OF CHICK EMBRYOS

Cartilage of chick embryos, 7 to 16 days of age, was incubated with [C-14]proline, [C-14]lysine, or [C-14]glutamic acid. The biosynthesis of [C-14]hydroxyproline, total [C-14]hydroxylysine, unglycosylated [C-14]hydroxylysine and glycosylated [C-14]hydroxylysine was assayed. Increased hydroxylation of [C-14]proline was observed up to day 14; and the total [C-14]hydroxylysine reached a plateau from day 10 to day 16. Glycosylated [C-14]hydroxylysine decreased after day 10. Although in the samples from 8- to 11-day-old tibiae, the values of glutamic acid expressed as dpm/bone per mu Ci per h increased, the participation in the process of hydroxyproline biosynthesis appeared constant if the values were expressed as percentage of total C-14. Differences in glycosylation of hydroxylysine during the embryogenesis of chicken indicates a considerable heterogeneity of collagen.