Hydorxyproline biosynthesis in plant cells Peptidyl proline hydroxylase from carrot disks

Abstract

Hydroxyproline occurs in many plant proteins and is especially abundant in the proteins associated with the primary cell wall. In vivo evidence indicates that the synthesis of peptidyl hydroxyproline occurs by the hydroxylation of peptidyl proline. We have shown that plant cells contain an enzyme which catalyzes this hydroxylation reaction. The hydroxylase has the following characteristics: it requires O2, Fe2+, ascorbate and an α-keto acid for activity; it does not react with free proline; it is localized in the soluble cytoplasm; it readily hydroxylates prolyl residues of protocollagen isolated from chick embryos. A partial purification of the enzyme was achieved by the use of (NH4)2SO4 and Ca3(PO4)2 gel fractionations. © 1971.