Raabe H M, Höpner J H, Notbohm H, Sinnecker G H, Kruse K, Müller P K
Klinik für Pädiatrie, Medizinische Universität zu Lübeck, Germany.
Diabetologia. 1998 Sep;41(9):1073-9. doi: 10.1007/s001250051032.
Glycation of basement membrane collagen IV has been implicated as a major pathogenetic process leading to diabetic microvascular complications. To evaluate the relevance of carbohydrate-induced modifications on collagen IV in diabetic nephropathy, we isolated the cross-linking domains 7S and NC1 from the glomerular basement membrane (GBM) of patients with diabetes mellitus. Modifications characteristic for glycated proteins were identified when the domains from diabetic kidney were compared with the same domains from human placenta as an unmodified control. In both domains a marked formation of inter-and intramolecular cross links could be demonstrated by SDS-PAGE. Furthermore circular dichroism studies showed a decrease in helicity of the 7S domain from human diabetic kidneys of 13%, indicating denaturation already at room temperature. Thermal transition profiles, showing a shift of the denaturation temperature towards a lower temperature, with loss of a distinct second melting point, confirmed this observation. Our data provide further evidence for a possible role of protein-modification by glycoxidative reactions in the onset of diabetic nephropathy in vivo.
IV型基底膜胶原蛋白的糖基化被认为是导致糖尿病微血管并发症的主要致病过程。为了评估碳水化合物诱导的修饰对糖尿病肾病中IV型胶原蛋白的相关性，我们从糖尿病患者的肾小球基底膜（GBM）中分离出交联结构域7S和NC1。当将糖尿病肾脏的结构域与来自人胎盘的相同结构域作为未修饰对照进行比较时，鉴定出糖基化蛋白质的特征性修饰。在两个结构域中，通过SDS-PAGE可以证明分子间和分子内交联的明显形成。此外，圆二色性研究表明，来自人类糖尿病肾脏的7S结构域的螺旋度降低了13%，表明在室温下就已经发生变性。热转变曲线显示变性温度向较低温度偏移，且失去了明显的第二个熔点，证实了这一观察结果。我们的数据为糖氧化反应对蛋白质的修饰在体内糖尿病肾病发病中的可能作用提供了进一步的证据。
