Deux glycopeptides a hydroxyproline dans l'urine humaine normale

Abstract

The presence of hydroxylproline-containing glycopeptides in normal human urine has been demonstrated. A preparation obtained from a lyophilisate of dialysed human urine was found to be soluble in 50% ethanol; it was not retained on a column of DEAE-cellulose equilibrated with 0.0005 M buffer of pH 8.5, but is retarded by filtration on dextran gel (Sephadex G-50) using 0.1 M acetic acid as eluting solvent. The glycopeptide nature of the bound hydroxyproline in this preparation was demonstrated by paper electrophoresis and paper chromatography, as well as by gel filtration on Sephadex after pronase digestion. During these different operations, a correlation was noted between hydroxyproline, NH 2 groups and carbohydrate substances. Two purified hydroxyproline-containing glycopeptides were obtained by preparative electrophoresis performed successively at pH 2.4 and 6.4. These glycopeptides are characterised not only by the presence of hydroxyproline but also by high proportions of proline (15%) and glycine (30%). The carbohydrate portion represents 30% of the molecule. After hydrolysis, carbohydrates were identified by paper chromatography. Galactose, glucosamine and galactosamine were the main carbohydrate substances in the two glycopeptides while fucose was present in smaller quantities; mannose was present in one of these glycopeptides and glucose and in the other. The importance of this new bound form of hydroxyproline was discussed in relation to the endogenous metabolism of collagen and the structure of this protein.