GEL ELECTROPHORETIC STUDIES OF ALPHA CHAINS AND OF MAJOR CNBR DERIVED PEPTIDES OF COLLAGEN OF GROWTH CARTILAGE IN OSTEOCHONDRODYSPLASIAS

Abstract

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 analyzed 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[sodium dodecyl sulfate]-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 1 case of lethal diastrophic dwarfism in which the pattern of peptides showed the presence of type 1 collagen in quantities detectable by the present method. In a milder case of diastrophic dwarfism the pattern of CNBr peptides was found normal. Possible abnormalities of collagen at a higher level of supramolecular organization in osteochondrodysplasias are not excluded.