Ghiso J, Wisniewski T, Vidal R, Rostagno A, Frangione B
Department of Pathology, New York University Medical Center, NY 10016.
Biochem J. 1992 Mar 1;282 ( Pt 2)(Pt 2):517-22. doi: 10.1042/bj2820517.
Two synthetic peptides with sequences identical with those of fragments of the extracellular domain of the Alzheimer's-disease amyloid precursor protein (APP) were used to raise antibodies. SP28 comprises positions 597-624 of the APP695 isoform, whereas SP41 extends towards the N-terminus (amino acids 584-624) and contains the entire SP28 peptide. Using e.l.i.s.a. and inhibition experiments we identified the two beta-turn-containing segments 602-607 and 617-624 as the epitopes recognized by anti-SP41 and anti-SP28 respectively. Both antibodies immunolabelled amyloid lesions in brains from Alzheimer's-disease patients and patients with related disorders, whereas they were unreactive in control brains. However, when probed on immunoblots, anti-SP28 failed to detect full-length APP from baculovirus-infected Sf9 cells, and anti-SP41 reacted weakly compared with other anti-APP antisera. The data suggest that these antibodies are directed to conformational epitopes not existent in the native molecules but present after alternative APP processing.
使用与阿尔茨海默病淀粉样前体蛋白（APP）细胞外结构域片段序列相同的两种合成肽来制备抗体。SP28包含APP695亚型的第597 - 624位氨基酸，而SP41向N端延伸（氨基酸584 - 624）并包含整个SP28肽段。通过酶联免疫吸附测定（ELISA）和抑制实验，我们分别鉴定出含β-转角的两个片段602 - 607和617 - 624为抗SP41和抗SP28识别的表位。两种抗体均能对阿尔茨海默病患者及相关疾病患者大脑中的淀粉样病变进行免疫标记，而在对照大脑中无反应。然而，在免疫印迹检测中，抗SP28未能检测到杆状病毒感染的Sf9细胞中的全长APP，并且与其他抗APP抗血清相比，抗SP41的反应较弱。数据表明，这些抗体针对的是天然分子中不存在但在APP经其他加工后出现的构象表位。
