Abstract
Soluble proline hydroxylase preparations were obtained from fetal rat skin, adult rat liver, guinea pig granuloma, as well as chick embryo. Proline-Cl4-rich, hydroxyproline-cl4-deficient proteins susceptible of degradation by bacterial collagenase have also been prepared from each of these tissues and have been shown to be hydroxylated by chick embryo proline hydroxylase. These studies represent the first demonstration of cell-free hydroxylation of peptidyl proline in tissues other than those ol chick embryo.