Niyibizi C, Eyre D R
Department of Orthopaedics, University of Washington, Seattle.
Eur J Biochem. 1994 Sep 15;224(3):943-50. doi: 10.1111/j.1432-1033.1994.00943.x.
To understand the role of type V collagen and its spatial interrelationship with type I collagen in bone matrix, the molecule's covalent intermolecular cross-links were structurally characterized. Type V collagen containing alpha 1(V), alpha 2(V) and alpha 1(XI) chains was isolated from bovine bone and reacted with NaB3H4 to label the cross-linking residues. Radiolabeled native molecules and isolated alpha chains were treated with sodium metaperiodate to cleave the divalent cross-linking bonds. Sequence analysis of the periodate-released peptides matched two of them to alpha 1(V) and alpha 1(XI) aminopropeptide domains. A third peptide was derived from the alpha 1(I) carboxytelopeptide domain of type I collagen. This latter peptide, therefore, came from a site of heterotypic cross-linking between types I and V collagens and accounted for about 15% of the total cross-linked peptides. Sequence analysis of isolated cross-linked tryptic peptides defined the helical sites of attachment of the periodate-released telopeptides and revealed that the putative aminoproteinase-cleavage sites in the alpha 1(V) and alpha 1(XI) chains are located in the molecule interior to the cross-linking residue. These data imply that type V collagen molecules in the extracellular matrix are primarily cross-linked to each other in a head-to-tail linear polymer that is linked laterally to type I collagen molecules in copolymeric fibrils.
为了解V型胶原蛋白在骨基质中的作用及其与I型胶原蛋白的空间相互关系，对该分子的共价分子间交联进行了结构表征。从牛骨中分离出含有α1(V)、α2(V)和α1(XI)链的V型胶原蛋白，并与NaB3H4反应以标记交联残基。用高碘酸钠处理放射性标记的天然分子和分离的α链，以裂解二价交联键。对高碘酸钠释放的肽段进行序列分析，发现其中两个与α1(V)和α1(XI)氨基端肽结构域匹配。第三个肽段来自I型胶原蛋白的α1(I)羧基端肽结构域。因此，后一种肽段来自I型和V型胶原蛋白之间异型交联的位点，约占总交联肽段的15%。对分离的交联胰蛋白酶肽段进行序列分析，确定了高碘酸钠释放的端肽的螺旋附着位点，并揭示α1(V)和α1(XI)链中假定的氨基蛋白酶切割位点位于交联残基内部的分子区域。这些数据表明，细胞外基质中的V型胶原蛋白分子主要以头对尾的线性聚合物形式相互交联，并在共聚物原纤维中横向连接到I型胶原蛋白分子上。
