DEVELOPMENT OF PROTOCOLLAGEN PROLINE HYDROXYLASE ACTIVITY IN CHICK EMBRYO

The activity of protocollagen proline hydroxylase, the enzyme hydroxylating proline residues in protocollagen, the proline-rich and hydroxyproline-deficient polypeptide precursor of collagen, was determined in the chick embryo during embryonic development. In whole chick embryos, the activity of this enzyme increased until the 14th day of embryonic development and thereafter declined. The activity of protocollagen proline hydroxylase was found to be present in all tissues tested, the highest activities being observed in bone and skin. These tissues showed the same type of development curve for this enzyme as whole embryos. In contrast, in the other tissues the enzyme activity did not change markedly during embryonic development. The changes in protocollagen proline hydroxylase activity correlated well with the changes observed in collagen synthesis in the developing chick embryo and thus support the earlier conclusions that the activity of this enzyme may be an indicator of collagen synthesis. Administration of ferrogluconate onto the chorioallantoic membrane led to a marked increase in protocollagen proline hydroxylase activity in whole embryo homogenates, whereas administration of ascorbate caused only a slight increase in activity. © 1969.