Study by gel electrophoresis, of alpha chains and of CNBr peptides of collagen from epiphyseal cartilage in chondrodysplasia

The alpha chains and the major CNBr - derived peptides of collagen of growth cartilage were studied in the following syndromes: thanatophoric dwarfism, pseudothanatophoric dwarfism, achondroplasia, pseudoachondroplasia, diastrophic dwarfism, metatropic dwarfism, Kniest disease, parastremmatic dwarfism, multiple exostoses, Blount disease and pycnodysostosis. After extraction of proteoglycans the collagen was solubilized by limited pepsin digestion purified, and the alpha chains were analysed by electrophoresis. The major CNBr - derived peptides were obtained by cleaving directly the cartilage after proteoglycan extraction. In some syndromes purified collagen was also cleaved. The CNBr peptides were analyzed by disc electrophoresis in SDS-polyacrylamide. Human normal growth cartilage and baboon cartilage were used as controls. The pattern of alpha chains and of major CNBr peptides was similar in all the cases studied, except one case of lethal diastrophic dwarfism in which the pattern of peptides showed the presence of type I collagen in quantities detectable by the present method. However in a milder case of diastrophic dwarfism the pattern of CNBr peptides was found normal. The present study does not exclude possible abnormalities of collagen at a higher lever of supramolecular organization in osteochondrodysplasias.