^aDepartments of Orthopaedics, University of Washington, Seattle, WA 98195, USA

^bDepartments of Biochemistry, University of Washington, Seattle, WA 98195, USA

Abstract

A major site of pyridinoline cross-linking in bovine type IX collagen was traced to a tryptic peptide derived from one of the molecule's HMW chains. This peptide gave two amino acid sequences (in ratio) consistent with it being a three-chained structure. The major sequence matched exactly that of the C-telopeptide of type II collagen from the same tissue. A second HMW chain that contained pyridinoline cross-links also gave two amino-terminal sequences, one from its own amino terminus, the other matching exactly the N-telopeptide cross-linking sequence of type II collagen. We conclude that type IX collagen molecules are covalently cross-linked in cartilage to molecules of type II collagen, probably at fibril surfaces.

Keywords: Collagen; Cross-linking; Amino acid sequence; (Bovine cartilage)

Abbreviations: HP, hydroxylysyl pyridinoline; LP, lysyl pyridinoline; HMW and LMW, triple-helical segments of the type IX collagen molecule released by pepsin; C-telopeptide and N-telopeptide, short sequences that form the amino- and carboxy-ends of types I, II and III collagen chains; HPLC, high-performance liquid chromatography