title: Accumulation of procollagen in the degenerative articular cartilage of dogs with osteoarthritis.
abstract: Collagen metabolism was studied in degenerative articular cartilage of dogs with spontaneous, early onset osteoarthritis. A fraction of collagen which represented about 1.5% of the total was extracted from cartilage samples with dilute phosphate buffer (pH 7.4) containing 0.2% sodium dodecyl sulfate. Agarose gel filtration in the presence of sodium dodecyl sulfate revealed that extracts of degenerative cartilage had about 24% procollagen whereas extracts of normal samples had only 3%. The isolated procollagen fraction was rechromatographed on agarose columns in the presence of mercaptoethanol. This resulted in the identification of a collagen species which migrated between marker beta and alpha collagen chains. The molecular weight of this collagen was estimated to be 150,000. Based on incorporation of [14C]proline, its ratio of hydroxy[14C]proline to total 14C was 0.32. Procollagen was not found after limited pepsin digestion (pH 3, 4 degrees C, 16 h) of degenerative cartilage samples. Since the total collagen content (microgram hydroxyproline/mg cartilage), hydroxy-[14C]proline/mg cartilage, specific radioactivity of hydroxyproline in the extractable collagen fraction were similar for normal and degenerative cartilage we propose that procollagen accumulated in the degenerative cartilage due to a partial defect in conversion of procollagen to collagen.
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000378:metabolism*; D002847:Chromatography, Agarose; D003094:Collagen / Q000378:metabolism; D004285:Dogs; D006909:Hydroxyproline / Q000378:metabolism; D008970:Molecular Weight; D010003:Osteoarthritis / Q000209:etiology / Q000378:metabolism*; D011347:Procollagen / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D011347:Procollagen; D003094:Collagen; D006909:Hydroxyproline