Knott L, Tarlton J F, Bailey A J
Division of Molecular and Cellular Biology, University of Bristol, Langford, U.K.
Biochem J. 1997 Mar 1;322 ( Pt 2)(Pt 2):535-42. doi: 10.1042/bj3220535.
With age, the proximal sections of turkey leg tendons become calcified, and this phenomenon has led to their use as a model for collagen mineralization. Mineralizing turkey leg tendon was used in this study to characterize further the composition and cross-linking of collagen in calcified tissues. The cross-link profiles of mineralizing collagen are significantly different from those of other collagenous matrices with characteristically low amounts of hydroxylysyl-pyridinoline and the presence of lysyl-pyridinoline and pyrrolic cross-links. However, the presence of the immature cross-link precursors previously reported in calcifying tissues was not supported in the present study, and was found to be due to the decalcification procedure using EDTA. Analysis of tendons from young birds demonstrated differences in the cross-link profile which indicated a higher level of hydroxylation of specific triple-helical lysines involved in cross-linking of the proximal tendon. This may be related to later calcification, suggesting that this part of the tendon is predestined to be calcified. The minimal changes in lysyl hydroxylation in both regions of the tendon with age were in contrast with the large changes in the cross-link profile, indicating differential hydroxylation of the helical and telopeptide lysine residues. Changes with age in the collagen matrix, its turnover and thermal properties in both the proximal and distal sections of the tendon clearly demonstrate that a new and modified matrix is formed throughout the tendon, and that a different type of matrix is formed at each site.
随着年龄增长，火鸡腿肌腱的近端部分会发生钙化，这种现象使其成为胶原矿化的一种模型。本研究使用矿化的火鸡腿肌腱来进一步表征钙化组织中胶原蛋白的组成和交联情况。矿化胶原蛋白的交联谱与其他胶原基质的交联谱显著不同，其特征在于羟赖氨酰吡啶啉含量低，同时存在赖氨酰吡啶啉和吡咯交联。然而，本研究不支持先前报道的钙化组织中存在未成熟交联前体的情况，并且发现这是由于使用乙二胺四乙酸（EDTA）进行脱钙过程导致的。对幼鸟肌腱的分析表明，交联谱存在差异，这表明参与近端肌腱交联的特定三螺旋赖氨酸的羟基化水平较高。这可能与后期钙化有关，表明肌腱的这一部分注定会发生钙化。肌腱两个区域中赖氨酰羟基化随年龄的最小变化与交联谱的巨大变化形成对比，表明螺旋和端肽赖氨酸残基的羟基化存在差异。肌腱近端和远端部分的胶原基质随年龄的变化、其更新和热性能清楚地表明，整个肌腱形成了一种新的、经过修饰的基质，并且每个部位形成了不同类型的基质。
