title: On the problem of covalent linkages between phosphoproteins and collagen in bovine dentin and bone.
abstract: The majority of phosphoproteins in bovine bone and dentin are insoluble in EDTA and guanidine hydrochloride (Gu.HCl) at 2 degrees C. After removal of EDTA and Gu.HCl-soluble proteins at 2 degrees C, collagen alpha-chains and alpha-chain polymers were extracted from bovine bone and dentin in Gu.HCl at elevated temperatures and purified by several chromatographic techniques and SDS-PAGE. Small amounts of O-phosphoserine were found in all collagen components. In contrast, O-phosphoserine was not detected in the purified collagen components soluble in EDTA or Gu.HCl at 2 degrees C nor was hydroxyproline detected in the EDTA-soluble phosphoproteins. In contrast, although the vast majority of EDTA-insoluble collagen and phosphoprotein molecules can be readily dissociated by a variety of molecular sieving and ion-exchange chromatographic procedures, a small number are very strongly associated or covalently cross-linked. These results are consistent with the findings that both hydroxyproline and hydroxylysine are present in purified phosphoprotein components released from the EDTA-insoluble tissue by bacterial collagenase. The hydroxylysine/100 hydroxyproline ratios in the phosphoprotein-collagen complexes are much higher than those in dentin or bone collagens.
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000032:analysis* / Q000196:embryology; D002417:Cattle; D055598:Chemical Phenomena; D002621:Chemistry; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D003094:Collagen / Q000302:isolation & purification; D003804:Dentin / Q000032:analysis*; D003810:Dentinogenesis; D004492:Edetic Acid; D010455:Peptides / Q000302:isolation & purification; D010750:Phosphoproteins / Q000302:isolation & purification; D012995:Solubility
chemical_list: D010455:Peptides; D010750:Phosphoproteins; D003094:Collagen; D004492:Edetic Acid