The putative 'link' glycopeptide associated with mucus glycoproteins. Composition and properties of preparations from the gastrointestinal tracts of several mammals.
The putative 'link' glycopeptide associated with mucus glycoproteins. Composition and properties of preparations from the gastrointestinal tracts of several mammals.
复制标题
假定的“连接”糖肽与粘液糖蛋白相关。
作者：
A. Roberton;M. Mantle;R. Fahim;R. Specian;A. Bennick;S. Kawagishi;P. Sherman;J. Forstner
上皮粘蛋白中是否存在离散的“连接”肽已争论多年。有证据表明，至少有一些粘蛋白含有一个特定的“连接”肽（或糖肽），通过形成二硫桥大粘蛋白糖蛋白亚基，增强粘蛋白聚合。一个主要的困难是要知道是否报告的差异，在假定的“链接”组件代表文物所产生的实验室间的差异，在粘蛋白纯化中使用的技术程序。本文概述了一项合作研究的结果，涉及5个实验室和53个样品的纯化胃肠道粘蛋白（包括唾液，胃，小肠和结肠粘蛋白）制备的5种技术从4种不同的动物。在所有情况下，粘蛋白纯化的早期步骤是加入蛋白酶抑制剂。代表性粘蛋白进行了分析，其组成，电泳迁移率在SDS/聚丙烯酰胺凝胶电泳之前和之后的二硫键还原，并与单特异性抗体开发的118 kDa的推定的“链接”糖肽分离的大鼠或人类小肠粘蛋白的反应。我们的研究结果表明，尽管在实验室技术，制备程序，器官和物种的差异，每个纯化的粘蛋白包含一个“链接”的组件，是由二硫键还原释放，并产生一个带SDS/聚丙烯酰胺凝胶电泳在约的位置。118 kDa。在电洗脱和分析后，发现来自不同粘蛋白的118 kDa条带具有相似的氨基酸谱并且含有碳水化合物。因此，似乎分子量约为1000的“连接”糖肽。118 kDa是所有研究的胃肠道粘蛋白共有的。
The existence of a discrete 'link' peptide in epithelial mucins has been debated for many years. There is evidence that at least some mucins contain a specific 'link' peptide (or glycopeptide) that enhances mucin polymerization by forming disulphide bridges to large mucin glycoprotein subunits. A major difficulty has been to know whether the reported differences in putative 'link' components represent artifacts generated by inter-laboratory differences in technical procedures used in mucin purification. The present paper outlines the results of a collaborative study involving five laboratories and 53 samples of purified gastrointestinal mucins (including salivary, gastric, small-intestinal and colonic mucins) prepared by five techniques from four different animal species. An early step in mucin purification in all cases was the addition of proteinase inhibitors. Representative mucins were analysed for their composition, electrophoretic mobility in SDS/polyacrylamide-gel electrophoresis before and after disulphide-bond reduction, and for their reactivity with monospecific antibodies developed against the 118 kDa putative 'link' glycopeptide isolated from either rat or human small-intestinal mucins. Our results indicate that, despite differences in laboratory techniques, preparative procedures, organs and species, each of the purified mucins contained a 'link' component that was released by disulphide-bond reduction and produced a band on SDS/polyacrylamide-gel electrophoresis at a position of approx. 118 kDa. After electroelution and analyses, the 118 kDa bands from the different mucins were found to have similar amino acid profiles and to contain carbohydrate. It would appear therefore that a 'link' glycopeptide of molecular mass approx. 118 kDa is common to all of the gastrointestinal mucins studied.