糖尿病患者红细胞膜蛋白糖基化与巯基氧化作用

Glycation and Thiol Oxidation of Erythrocyte Membrane Proteins in Diabetes

非胰岛素依赖型糖尿病(NIDDM)患者,红细胞膜蛋白的糖基化水平与巯基氧化作用呈正相关(r=0.55)。与正常人红细胞膜的体外糖基化结果类似。为了证明糖基化能提高膜蛋白中巯基氧化的敏感性,在体外用Aspirin乙酰化封闭红细胞膜蛋白中可被糖基化的部位,可使糖基化抑制50％,氧化作用抑制33％;反之用维生素E代替Aspirin,则膜蛋白氧化作用降低44％,而糖基化仅降低12％。上述结果提示,糖基化可能引起膜蛋白构型改变,使硫氢基暴露,从而加速其氧化作用。膜蛋白的糖基化和氧化作用与糖尿病并发症及老年病密切相关。

In this paper, the results of study on the glycation and thiol oxidation of erythrocyte membrane proteins in non-insulin dependent diabetes have been presented. Our results indicate a positive correction between membrane glycation and thiol oxidation (r = 0.55) in diabetic patients (NIDDM) . In vitro studies on normal human erythrocyte membrane had shown a time- and concentration-dependent increase in glycation and thiol oxidation with the increase of concentration of incubated glucose. In order to show that glycation enhances the susceptibility of thiol oxidation, we inhibited glycation by blocking sites of glycation by acety lation with Aspirin. A 20mM Aspirin could inhibit glycation by 50% and thiol oxidation up to 33% in vitro. A 2.4U of vitamin E,an antioxidant,significantly lowered thiol oxidation (44%) and slightly reduced the glycation by 12% in vitro. These results indicate that glycation may have the potential to bring a con-formational change of erythrocyte membrane protein and expose the thiol groups which can accelerate the oxidation of erythrocyte membrane proteins. The changes of glyca tion and oxidation of erythrocyte membrane proteins are association with the development of diabetic complications.