Spritz N, Singh H, Marinan B, Silberlicht I
Diabetes. 1981 Apr;30(4):292-5. doi: 10.2337/diab.30.4.292.
To investigate abnormalities in peripheral nerve myelin in experimental diabetes, we studied the effects of the proteolytic enzymes trypsin and alpha-chymotrypsin on the proteins of this membrane, obtained from the sciatic nerves of normal rats and from animals made diabetic with streptozotocin. The dominant effect of the proteolytic enzymes was to incompletely degrade the major membrane protein (mol. wt. 28,000), with the appearance of new protein (mol. wt. 20,000). Using myelin isolated from the nerves of diabetic animals, the reaction was approximately one-half that of the controls (P less than 0.01) for both enzymes. When, however, the myelin protein affected by trypsin and chymotrypsin was isolated from the membrane and then incubated with the proteolytic enzyme, its proteolysis was complete and took place at the same rate in the diabetic animals and controls. These findings suggest that, in this model of experimental diabetes, there is an alteration in the structure of peripheral nerve myelin that inhibits interaction between the protein in the membrane bilayer and two water soluble proteolytic enzymes. This alteration could not be demonstrated in protein isolated from the membrane, suggesting that the change relates to the interaction of the protein and other components of myelin, rather than to chemical alteration in the protein per se.
为了研究实验性糖尿病中周围神经髓鞘的异常情况，我们研究了蛋白水解酶胰蛋白酶和α-糜蛋白酶对从正常大鼠坐骨神经以及用链脲佐菌素诱导糖尿病的动物坐骨神经中获取的该膜蛋白的影响。蛋白水解酶的主要作用是不完全降解主要膜蛋白（分子量28,000），并出现新的蛋白（分子量20,000）。对于两种酶，使用从糖尿病动物神经中分离的髓鞘，其反应约为对照组的一半（P小于0.01）。然而，当从膜中分离出受胰蛋白酶和糜蛋白酶影响的髓鞘蛋白，然后与蛋白水解酶一起孵育时，其蛋白水解是完全的，并且在糖尿病动物和对照组中以相同的速率发生。这些发现表明，在这个实验性糖尿病模型中，周围神经髓鞘的结构发生了改变，这种改变抑制了膜双层中的蛋白与两种水溶性蛋白水解酶之间的相互作用。这种改变在从膜中分离的蛋白中无法得到证实，这表明这种变化与蛋白和髓鞘其他成分之间的相互作用有关，而不是与蛋白本身的化学改变有关。
