Duhamel R C, Meezan E, Brendel K
Exp Eye Res. 1983 Feb;36(2):257-67. doi: 10.1016/0014-4835(83)90010-6.
Basement membranes isolated from the entire neural retinae of normal cows consist of a heterogeneous mixture of polypeptides resolvable as two major populations, one collagenous and the other non-collagenous. The non-collagenous population consists of disulfide-bonded aggregates of which the major fraction is soluble in lithium dodecyl sulfate (LDS) at 4 degrees C without reducing agent, with the remainder requiring reduction for solubilization at 4 degrees C. Only the second 4 degrees C extract is contaminated with small amounts of hydroxylated amino acids. The non-collagenous population consists of up to 25 polypeptides detectable in sodium dodecyl sulfate (SDS) gels, all of which stain blue with Coomassie Blue R-250, are insensitive to bacterial collagenase and migrate on or slightly below the central diagonal in urea-SDS/SDS electrophoresis. The collagenous population is soluble in LDS at 100 degrees C under reducing conditions and has a collagenous amino acid composition, although consisting of only 272 glycine residues/1000. This fraction consists of four major and four minor polypeptides detectable in SDS gels, all of which stain red (metachromatically) with Coomassie Blue R-250, are degraded by bacterial collagenase and migrate below the central diagonal in urea-SDS/SDS electrophoresis. The four major collagenous polypeptides are larger than the alpha-chains of type I collagen. In total, the solubilized proteins account for 60% of the general protein, but only 30% of the sum of hydroxyproline and hydroxylysine. The insoluble residue has a collagenous amino acid composition similar to that of the 100 degrees C extract, but with lower 3-hydroxyproline and hydroxylysine contents.
从正常奶牛的整个神经视网膜分离出的基底膜由多肽的异质混合物组成，可解析为两个主要群体，一个是胶原质的，另一个是非胶原质的。非胶原质群体由二硫键结合的聚集体组成，其中大部分在4℃下可溶于十二烷基硫酸锂（LDS），无需还原剂，其余部分在4℃下溶解则需要还原。只有第二次4℃提取物被少量羟基化氨基酸污染。非胶原质群体由多达25种在十二烷基硫酸钠（SDS）凝胶中可检测到的多肽组成，所有这些多肽用考马斯亮蓝R-250染成蓝色，对细菌胶原酶不敏感，并且在尿素-SDS/SDS电泳中迁移到中心对角线或略低于中心对角线的位置。胶原质群体在还原条件下于100℃可溶于LDS，具有胶原质氨基酸组成，尽管每1000个中仅含272个甘氨酸残基。该部分由在SDS凝胶中可检测到的四种主要和四种次要多肽组成，所有这些多肽用考马斯亮蓝R-250染成红色（异染性），可被细菌胶原酶降解，并且在尿素-SDS/SDS电泳中迁移到中心对角线以下的位置。四种主要的胶原质多肽比I型胶原的α链大。总的来说，溶解的蛋白质占总蛋白质的60%，但仅占羟脯氨酸和羟赖氨酸总和的30%。不溶性残渣具有与100℃提取物相似的胶原质氨基酸组成，但3-羟脯氨酸和羟赖氨酸含量较低。
