Shibata S, Miura K
J Biochem. 1981 Jun;89(6):1737-49. doi: 10.1093/oxfordjournals.jbchem.a133373.
A new glycopeptide was isolated from the glomerular basement membrane (GBM) of normal rats. Unlike already known glycopeptides, this glycopeptide has biological activity (nephritogenic activity) to induce glomerulonephritis when injected once into the footpads of homologous animals. A close relationship was found between the nephritogenic activity and the non-dialyzable glucose content of this glycopeptide. Thus the nephritogenic activity can be assessed quantitatively by estimating the content of "non-dialyzable glucose." Chemical purification of the nephritogenic glycopeptide involved the selective removal of inactive glycopeptide containing galactose, mannose, and N-acetyl-glucosamine (but no glucose). Trichloroacetic acid (TCA) treatment was a simple but highly effective procedure for selective removal of this inactive glycopeptide. The non-reducing terminus of the nephritogenic glycopeptide is alpha-D-glucopyranoside, and the glycopeptide reacts specifically with concanavalin A, even in the crude state. We propose that the nephritogenic glycopeptide is not an artifact produced during exhaustive proteolytic digestion, but a natural substance having a fixed molecular shape, even in the crude state, and whose union with GBM-proper can be easily broken by proteolytic digestion.
从正常大鼠的肾小球基底膜（GBM）中分离出一种新的糖肽。与已知的糖肽不同，这种糖肽具有生物活性（致肾炎活性），当单次注射到同源动物的足垫中时可诱发肾小球肾炎。发现这种糖肽的致肾炎活性与其不可透析的葡萄糖含量之间存在密切关系。因此，通过估计“不可透析的葡萄糖”含量可以定量评估致肾炎活性。致肾炎糖肽的化学纯化涉及选择性去除含有半乳糖、甘露糖和N-乙酰葡糖胺（但不含葡萄糖）的无活性糖肽。三氯乙酸（TCA）处理是选择性去除这种无活性糖肽的简单但高效的方法。致肾炎糖肽的非还原末端是α-D-吡喃葡萄糖苷，并且即使在粗品状态下，该糖肽也能与伴刀豆球蛋白A特异性反应。我们提出，致肾炎糖肽不是在彻底的蛋白水解消化过程中产生的假象，而是一种即使在粗品状态下也具有固定分子形状的天然物质，并且其与肾小球基底膜本身的结合可以通过蛋白水解消化轻易破坏。
