Electron microscopic studies on collagen fibrillogenesis.

1.我们以前发现，胶原蛋白分子在pH 4.5下缔合，特异性地形成4D交错的线性聚合物，这被认为是体外胶原原纤维形成的第一中间体。在这项研究中，我们证实了4D交错聚集体（含有不同的聚合度）被纳入天然型D-周期性纤维在生理条件下。我们打算通过凝胶过滤分离不同聚合度的低聚物，并分配每个低聚物在胶原纤维形成中的作用。试验尚未成功。对胶原自组装第一步分子缔合形式（二聚体）的电镜鉴定条件进行了研究，并对各种方法进行了优化。我们发现Ⅰ型胶原分子束（SLS）的负染带型与分子沿着疏水氨基酸的分布有直接的相关性。与I型和II型胶原蛋白的相关性得到证实.非螺旋部分的胶原蛋白分子（端肽）被发现参与的4D交错协会在pH 4.5.4。在体外原纤维形成的早期阶段所取的样品的电子显微镜检查表明，除了细丝之外，还存在D-周期原纤维（X射线观察）。

1. We previously found that collagen molecules associate at pH 4.5 to specifically form 4D-staggered linear polymers, which are assumed to be the first intermediates in in vitro collagen fibrillogenesis. In this study, we confirmed that the 4D-staggered aggregates (containing various degrees of polymerization) are incorporated into native-type D-periodic fibrils under the physiological conditions. We intended to isolate the oligomers of the different polymericity by gel filtration and to assign the role of each oligomer in collagen fibrillogenesis. The trials were not yet successful.2. Conditions for electron microscopic identification of the association form of the molecules (dimer) at the first step of collagen self-assembly were investigated and individual methods were optimized. We noticed the direct correlation between negatively stained banding patern of type I collagen molecular bundle (SLS) and the distribution of hydrophobic amino acids along the molecule. The correlation was confirmed with type I and type II collagens.3. Non-helical parts of the collagen molecule (telopeptide) were revealed to be involved in the 4D-staggered association at pH 4.5.4. Electron microscopic examination of the sample taken at an early stage of the in vitro fibrillogenesis showed the existance of D-periodic fibrils in addition to thin filaments (preliminaly obsevation).