Molecular characteristics of a protease-resistant, amyloidogenic and neurotoxic peptide homologous to residues 106-126 of the prion protein.
Molecular characteristics of a protease-resistant, amyloidogenic and neurotoxic peptide homologous to residues 106-126 of the prion protein.
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DOI：
10.1006/bbrc.1993.1977
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发表时间：
1993-08
影响因子：
3.1
通讯作者：
C. Selvaggini;L. De Gioia;L. Cantu';E. Ghibaudi;L. Diomede;F. Passerini;G. Forloni;O. Bugiani;F. Tagliavini;M. Salmona
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文献类型：
--
作者：
C. Selvaggini;L. De Gioia;L. Cantu';E. Ghibaudi;L. Diomede;F. Passerini;G. Forloni;O. Bugiani;F. Tagliavini;M. Salmona
在朊病毒相关的脑病中，朊病毒蛋白转化为一种改变的形式，称为PrPSc，它对蛋白酶消化有部分抗性。这种异常的同种型在脑中积累，其蛋白酶抗性核心在细胞外聚集成淀粉样纤维。我们已经调查了构象特性，聚集行为和蛋白酶消化的合成肽同源的残基106-126的人PrP，这是以前发现形成淀粉样纤维在体外，并显示对原代培养的大鼠海马神经元的神经毒性活性。使用肽PrP 106-126的乱序序列作为对照。通过圆二色性，PrP 106-126显示出主要由β-折叠组成的二级结构，而PrP 106-126的杂乱序列显示出无规卷曲结构。PrP 106-126的β-折叠含量在pH 5.0的200 mM磷酸盐缓冲液中比在pH 7.0的相同缓冲液中高得多。激光散射分析表明，PrP 106-126在20 mM或200 mM磷酸盐缓冲液（pH 5.0和7.0）中溶解后立即聚集，而乱序PrP 106-126则没有。PrP 106-126聚集体的平均水力直径为100 nm，平均分子量为12 x 10（6）+/-30%道尔顿，相当于6000 +/-30%分子的聚集。肽PrP 106-126显示出对蛋白酶K和链霉蛋白酶消化的部分抗性，而乱序PrP 106-126通过与酶在37 ° C下孵育30分钟而完全降解。
In the prion-related encephalopathies the prion protein is converted to an altered form, known as PrPSc, that is partially resistant to protease digestion. This abnormal isoform accumulates in the brain and its protease-resistant core aggregates extracellularly into amyloid fibrils. We have investigated the conformational properties, aggregation behaviour and sensitivity to protease digestion of a synthetic peptide homologous to residues 106-126 of human PrP, which was previously found to form amyloid-like fibrils in vitro and displayed neurotoxic activity toward primary cultures of rat hippocampal neurons. A scrambled sequence of peptide PrP 106-126 was used as a control. By circular dichroism, PrP 106-126 exhibited a secondary structure composed largely of beta-sheet, whereas the scrambled sequence of PrP 106-126 showed a random coil structure. The beta-sheet content of PrP 106-126 was much higher in 200 mM phosphate buffer at pH 5.0 than in the same buffer at pH 7.0. Laser light scattering analysis showed that PrP 106-126 aggregated immediately after dissolution in 20 mM or 200 mM phosphate buffer, pH 5.0 and 7.0, whereas scrambled PrP 106-126 did not. PrP 106-126 aggregates had an average hydrodinamic diameter of 100 nm and an average molecular weight of 12 x 10(6) +/- 30% Daltons, corresponding to the aggregation of 6000 +/- 30% molecules. Peptide PrP 106-126 showed partial resistance to digestion with Proteinase K and Pronase, whereas scrambled PrP 106-126 was completely degraded by incubation with the enzymes at 37 degrees C for 30 minutes.