Bone Type V Collagen: Chain Composition and Location of a Trypsin Cleavage Site

Abstract

The component α-chains of type V collagen from bovine bone were isolated and structurally characterized by gel electrophoresis, high performance liquid chromatography (HPLC) and amino acid sequence analysis. Three distinct α-chains were identified. Two of these were the well described α1(V) and α2(V) chains; the third proved to be identical to the cartilage α1(XI) chain. In adult bone the ratio between the three chains was about 1:1:1. Native type V collagen was cleaved by trypsin at 33°C or 37°C into 3/5 fragments. Aminoterminal sequence analysis of the α1(V) and α1(XI) fragments showed they both resulted from trypsin cleavage between residue 434 and 435. Trypsin apparently cleaves the type V molecule within a relatively unstable domain of the triple helix which presumably may also be a natural site of initial cleavage by a protease in vivo.

Key Words:

• Collagen (type V, bovine)
• bone
• cartilage