In vitro peroxidase oxidation induces stable dimers of β-amyloid (1-42) through dityrosine bridge formation
In vitro peroxidase oxidation induces stable dimers of β-amyloid (1-42) through dityrosine bridge formation
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DOI：
10.3109/13506129908993282
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发表时间：
1999-03-01
期刊：
影响因子：
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通讯作者：
Giunta, S
中科院分区：
文献类型：
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作者：
Galeazzi, L;Ronchi, P;Giunta, S
β -淀粉样蛋白（A β）是一种存在于脑脊液（CSF）和其他生物体液中的正常可溶性肽。A -原纤维与阿尔茨海默病（AD）老年斑有关。我们使用纯化的可溶性A β(1-42)和A β(12-28)肽，以确定暴露于过氧化物酶和过氧化氢在这些肽中诱导的氧化修饰。我们已经证明，在这些体外条件下，二聚体形式的A β(1-42)可以通过高分辨率聚丙烯酰胺SDS-PAGE电泳检测到。通过反相高效液相色谱（RP-HPLC）和荧光缺陷监测的进一步实验表明，过氧化物酶反应诱导的二聚体A β(1-42)形式是二酪氨酸桥形成的结果。这种交联是酶催化氧化的结果。在这个反应中，两个A β(1-42)肽的酪氨酸残基发生酚偶联。缺乏酪氨酸残基的A β(12-28)肽未观察到可检测到的过氧化修饰。由于氧化应激被认为与阿尔茨海默病有关，本文描述的实验模型可以帮助理解在sA β转化为淀粉样蛋白原纤维并最终形成老年斑之前导致化学、结构和构象修饰的早期事件。
beta-amyloid (A beta) is a normal soluble peptide found in the cerebrospinal fluid (CSF) and other biological fluids. A beta fibrils are associated with Alzheimer's disease (AD) senile plaques. We have used purified soluble A beta (1-42) and A beta (12-28) peptides in order to determine the oxidative modification induced in these peptides by exposure to peroxidase and hydrogen peroxide. We have demonstrated that under these in vitro conditions, dimeric forms of A beta (1-42) can be detected by high-resolution polyacrylamide SDS-PAGE electrophoresis. Further experiments performed by reverse-phase high performance liquid chromatography (RP-HPLC), and monitored by fluorescence defection, showed that the dimeric A beta (1-42) forms induced by the peroxidase reaction are the outcomes of dityrosine bridge formation. This cross-link results from the enzyme catalyzed oxidation. During this reaction, phenolic coupling of tyrosine residues of two A beta (1-42) peptides occurs. Mo detectable peroxidative modifications were observed with the A beta(12-28)peptide which lacks a tyrosine residue Since oxidative stress is thought to be associated with AD, the experimental model described here can help in understanding the early events leading to chemical, structural and conformational modifications before the conversion of sA beta to amyloid fibrils and eventually the formation of senile plaques in AD.