Structural diversity and domain composition of a unique collagenous fragment (intima collagen) obtained from human placenta.
Structural diversity and domain composition of a unique collagenous fragment (intima collagen) obtained from human placenta.
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从人胎盘中获得的独特胶原片段（内膜胶原）的结构多样性和结构域组成。
作者：
E. Odermatt;J. Risteli;Vera Van DELDENt;Rupert Timplt
从人胎盘的胃蛋白酶消化酶中获得两种形式的内膜胶原，其组成多肽链的大小在一定程度上不同（Mr 50 000-70 000）。这些链通过二硫键连接到大的聚集体。聚集体排列成三螺旋构象，具有非常高的热稳定性（Tm 41-62 ℃），并且对进一步的蛋白水解消化具有抗性。还原低至5%的二硫键主要产生单体三螺旋（Mr约160 000），Tm为32 ℃。部分还原的物质可以通过蛋白水解分离成三螺旋和非胶原结构域。胃蛋白酶释放一种胶原成分，分子量为38000。细菌胶原酶释放两个富含胱氨酸的非胶原片段（Mr 15 000-30 000）。在减少之前用胶原酶处理将内膜胶原分离成由胶原性（Tm 41 ° C）和非胶原性结构组成的大片段和单个非胶原性片段。数据支持内膜胶原的电子显微镜模型[Furthmayr，Wiedemann，Timpl，Odermatt & Engel（1983）Biochem.J.211，303-311]，表明片段的基本单元由连接两个球状结构域的连续三螺旋组成。
Intima collagen was obtained from pepsin digests of human placenta in two forms, which differ to some extent in the size of their constituent polypeptide chains (Mr 50 000-70 000). These chains are connected by disulphide bonds to large aggregates. The aggregates are arranged in a triple-helical conformation with a remarkably high thermal stability (Tm 41-62 degrees C) and are resistant to further proteolytic digestion. Reduction of as little as 5% of the disulphide bonds produces mainly monomeric triple helices (Mr about 160 000) with Tm 32 degrees C. Partially reduced material can be separated into triple-helical and non-collagenous domains by proteolysis. Pepsin releases a collagenous component with chains of Mr 38 000. Bacterial collagenase liberates two non-collagenous segments (Mr 15 000-30 000) rich in cystine. Treatment with collagenase before reduction separates intima collagen into a large fragment composed of collagenous (Tm 41 degrees C) and non-collagenous structures and a single non-collagenous segment. The data support the electron-microscopical model of intima collagen [Furthmayr, Wiedemann, Timpl, Odermatt & Engel (1983) Biochem. J. 211, 303-311], indicating that the basic unit of the fragment consists of a continuous triple helix joining two globular domains.