Inuzuka T, Sato S, McIntyre L J, Quarles R H
J Neurochem. 1984 Aug;43(2):582-5. doi: 10.1111/j.1471-4159.1984.tb00938.x.
Human and rat myelin preparations were incubated with varying concentrations of trypsin and plasmin to determine the effects of these proteolytic enzymes on myelin-associated glycoprotein (MAG), basic protein, and other myelin proteins and to compare the effects with those of the neutral protease that was reported to be endogenous in myelin. Basic protein was most susceptible to degradation by both trypsin and plasmin, whereas MAG was relatively resistant to their actions. Under the assay conditions used, the highest concentrations of trypsin and plasmin degraded greater than 80% of the basic protein but less than 30% of the MAG, and lower concentrations caused significant loss of basic protein without appreciably affecting MAG. Neither trypsin nor plasmin caused a specific cleavage of MAG to a derivative of MAG (dMAG) in a manner analogous to the endogenous neutral protease. Thus the endogenous protease appears unique in converting human MAG to dMAG much more rapidly than it degrades basic protein. MAG is slowly degraded along with other proteins when myelin is treated with trypsin or plasmin, but it is less susceptible to their action than is basic protein.
将人源和大鼠源髓磷脂制剂与不同浓度的胰蛋白酶和纤溶酶一起孵育，以确定这些蛋白水解酶对髓鞘相关糖蛋白（MAG）、碱性蛋白和其他髓鞘蛋白的影响，并将这些影响与据报道在髓鞘中内源性存在的中性蛋白酶的影响进行比较。碱性蛋白对胰蛋白酶和纤溶酶的降解最敏感，而MAG对它们的作用相对具有抗性。在所使用的测定条件下，胰蛋白酶和纤溶酶的最高浓度可降解超过80%的碱性蛋白，但降解的MAG不到30%，较低浓度会导致碱性蛋白显著损失，而对MAG没有明显影响。胰蛋白酶和纤溶酶都不会以类似于内源性中性蛋白酶的方式将MAG特异性切割成MAG衍生物（dMAG）。因此，内源性蛋白酶在将人源MAG转化为dMAG方面似乎具有独特性，其速度比降解碱性蛋白快得多。当用胰蛋白酶或纤溶酶处理髓磷脂时，MAG会与其他蛋白质一起缓慢降解，但它比碱性蛋白更不易受到它们的作用。
