Incorporation of proline analogs into procollagen: Assay for replacement of imino acids by cis-4-hydroxy- l-proline and cis-4-fluoro- l-proline

Abstract

Previously, several proline analogs have shown to be incorporated into protein and, in particular, into procollagen polypeptides. Here a new technique was used to determine the extent to which two proline analogs, cis-4-hydroxy- l-proline and cis-4-fluoro- l-proline, replaced proline and hydroxyproline in newly synthesized pro-α and pro-γ chains of procollagen. Matrix-free chick embryo tendon cells, when incubated with 1.53 m m, cis-4-hydroxy- l-proline, synthesized collagenous polypeptides in which from 13 to 19% of the total imino acid residues were replaced with the analog. Incubation of cells with 1.50 m m, cis-4-fluoro- l-proline resulted in the synthesis of polypeptides in which 27% of the imino acid residues were replaced by the analog. With lower concentrations, proportionally less of the analog was incorporated into protein. The observations here extend previous indications that proline analogs in relatively low concentrations may have a specific effect on the synthesis of collagen.