An unusual pattern of peptide-bound lysine metabolism in collagen from an infant with lethal perinatal osteogenesis imperfecta.

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RESUMO

Collagens extracted from bones, cartilage, dermis, and dura mater of an infant with type II (lethal perinatal) osteogenesis imperfecta were evaluated with respect to chain composition and chemical characteristics of their constituent chains. The results indicated that the various types of collagen were present in the indicated tissues in proportions that approximated normal tissues. Nevertheless, the constituent chains of collagens extracted from dermis, i.e., alpha 1(I), alpha 2(I), alpha 1(III), alpha 1(V), and alpha 2(V), chromatographed on carboxymethyl cellulose as though they possessed substantially lower overall positive charge than the homologous chains of normal tissues. Amino acid analyses of the chains confirmed this observation and showed that the chains lacked five to seven residues of lysine (plus hydroxylysine). It was subsequently shown that the apparent deficiency in lysyl residues was due, at least in part, to the presence of unusually high levels of allysine , a cross-link precursor formed from peptide-bound lysine under the catalytic action of lysyl oxidase. These results, in conjunction with previous results obtained on collagens from type II osteogenesis imperfecta tissues, suggest that aberrant fibril formation in this syndrome allows increased lysyl oxidase activity.

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