Hong B S, Davison P F
Ophthalmic Res. 1985;17(3):162-7. doi: 10.1159/000265368.
A procollagen in the soluble fraction of rabbit vitreous was isolated by dialysis against dilute acetic acid and partially purified by Bio-Gel A 5M gel filtration. The molecule was identified to be type II procollagen by comparing its segment-long-spacing (SLS) banding pattern with that of standard type II collagen isolated from rabbit articular cartilage. Electron microscopy of the SLS of this type II procollagen revealed a fuzzy propeptide extension at the N-terminal end of the molecule. Pepsin digestion of the procollagen removed this extension, thus converting the molecule into a collagen which had mobility similar to that of pepsin-soluble cartilage type II collagen in SDS-polyacrylamide gel electrophoresis. No inter-chain disulfide bond was found in the propeptide extension when the procollagen samples were electrophoresized with or without mercaptoethanol. Comparison of the cyanogen bromide peptide map of the type II procollagen with that of the pepsin-soluble type II collagen indicated that two extra peptides were present in the digest of procollagen. All of this evidence suggested that the procollagen in the soluble vitreous body of the rabbit eye was a novel type II procollagen with a propeptide extension only at the N-terminus.
通过对稀醋酸进行透析，从兔玻璃体的可溶部分分离出一种前胶原，并通过Bio-Gel A 5M凝胶过滤进行部分纯化。通过将其片段长间距（SLS）条带模式与从兔关节软骨分离出的标准II型胶原的条带模式进行比较，确定该分子为II型前胶原。对这种II型前胶原的SLS进行电子显微镜观察，发现在分子的N末端有一个模糊的前肽延伸。用胃蛋白酶消化前胶原可去除该延伸部分，从而将该分子转化为一种在SDS-聚丙烯酰胺凝胶电泳中具有与胃蛋白酶可溶的软骨II型胶原相似迁移率的胶原。当对前胶原样品进行有无巯基乙醇的电泳时,在前肽延伸部分未发现链间二硫键。将II型前胶原的溴化氰肽图谱与胃蛋白酶可溶的II型胶原的图谱进行比较，表明在前胶原的消化物中存在两种额外的肽。所有这些证据表明，兔眼可溶玻璃体中的前胶原是一种新型的II型前胶原，仅在N末端有前肽延伸。
