Effect of glycosylation on the stability of alpha(1)-antitrypsin toward urea denaturation and thermal deactivation
Effect of glycosylation on the stability of alpha(1)-antitrypsin toward urea denaturation and thermal deactivation
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DOI：
10.1016/s0304-4165(96)00143-2
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发表时间：
1997-06-06
影响因子：
3
通讯作者：
Yu, MH
中科院分区：
文献类型：
--
作者：
Kwon, KS;Yu, MH
研究了糖基化对人α（1）-抗胰蛋白酶稳定性的影响。尿素诱导的非糖基化重组体、糖基化酵母版本和人血浆α（1）-抗胰蛋白酶平衡解折叠的转变中点在25 ℃时分别为1.8 M、2.2 M和2.5 M。展开和重折叠的动力学分析表明，糖基化延缓展开，而不影响重折叠速率显着，这表明稳定性的增加是由于稳定的天然状态，而不是不稳定的展开状态。在热失活中，这是一种热诱导的聚集过程，非糖基化重组α（1）-抗胰蛋白酶最容易失活，其次是酵母和血浆形式。结果表明，糖基化赋予α（1）-抗胰蛋白酶稳定性的增加，并且存在于酵母形式上的低聚甘露糖产生比血浆形式上的复合型糖更不稳定的分子。看来，糖基化对耐热性增强的影响是通过增加构象稳定性来实现的。然而，显示与血浆形式相同的构象稳定性的稳定重组变体（Phe 51 -> Cys）比血浆α（1）-抗胰蛋白酶对热变性的抗性更低。结果表明，α（1）-抗胰蛋白酶聚集的动力学稳定性与糖基的存在和构象稳定性有关。
The effects of glycosylation on the stability of human alpha(1)-antitrypsin were investigated. The transition midpoints in urea-induced equilibrium unfolding of a non-glycosylated recombinant, a yeast version of glycosylated, and human plasma alpha(1)-antitrypsin were 1.8 M, 2.2 M, and 2.5 M at 25 degrees C, respectively. Kinetic analyses of unfolding and refolding revealed that glycosylation retarded the unfolding without affecting the refolding rate significantly, suggesting that the stability increase is due to the stabilization of the native state as opposed to the destabilization of the unfolded state. In thermal deactivation, which is a heat-induced aggregation process, the ungycosylated recombinant alpha(1)-antitrypsin was deactivated most easily, which was followed in order by the yeast, and the plasma form. The results indicate that glycosylation confers the increase in stability of alpha(1)-antitrypsin, and that the oligomannose sugars present on the yeast form produce a less stable molecule than the complex type sugars on the plasma form. It appears that the effect of glycosylation on the enhancement of thermal resistance is exerted through the increase in conformational stability. However, a stable recombinant variant (Phe 51 --> Cys) that showed the same conformational stability as the plasma form was less resistant to thermal denaturation than the plasma alpha(1)-antitrypsin. The results suggest that the existence of carbohydrate moiety per se as well as the conformational stability contribute to the kinetic stability of alpha(1)-antitrypsin toward aggregation.