Appearance of sodium dodecyl sulfate-stable amyloid beta-protein (Abeta) dimer in the cortex during aging.
Appearance of sodium dodecyl sulfate-stable amyloid beta-protein (Abeta) dimer in the cortex during aging.
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衰老过程中皮质中十二烷基硫酸钠稳定的淀粉样β蛋白（Abeta）二聚体的出现。
作者：
M. Enya;M. Morishima;M. Yoshimura;Y. Shinkai;K. Kusui;K. Khan;D. Games;D. Schenk;S. Sugihara;H. Yamaguchi;Y. Ihara
我们之前注意到，通过酶免疫分析 (EIA) 检测，一些老年人类皮质样本中淀粉样 β 蛋白 (As) 的水平非常低或可忽略不计，在蛋白质印迹上提供了 6 约 8 kd 处的显着信号，可能代表十二烷基硫酸钠 (SDS) 稳定的 Abeta 二聚体。对 EIA 特异性的重新检查表明，基于 BAN50 和 BNT77 的 EIA 最常用于 Abeta 定量，捕获 SDS 可解离的 Abeta，但不能捕获 SDS 稳定的 Abeta 二聚体。因此，对所有 Abeta 水平低于 EIA 检测限的皮质样本进行蛋白质印迹分析。从印迹判断，此类样本的一部分含有约 8 kd 处的 SDS 稳定二聚体，但不含约 4 kd 处的 SDS 可解离的 Aβ 单体。这种 A(β) 二聚体不太可能在死后产生，因为 (i) 死后延迟非常短的标本含有 A(β) 二聚体，(ii) 直到死后 12 小时，这种 SDS 稳定的 A(β) 二聚体在 PDAPP 转基因小鼠中仅微弱地检测到。皮质中A(β)二聚体的存在可能是A(β)在人脑中积累的特征，该过程比PDAPP转基因小鼠中的积累时间要长得多。
We previously noted that some aged human cortical specimens containing very low or negligible levels of amyloid beta-protein (As) by enzyme immunoassay (EIA) provided prominent signals at 6 approximately 8 kd on the Western blot, probably representing sodium dodecyl sulfate (SDS)-stable Abeta dimer. Re-examination of the specificity of the EIA revealed that BAN50- and BNT77-based EIA, most commonly used for the quantitation of Abeta, capture SDS-dissociable Abeta but not SDS-stable Abeta dimer. Thus, all cortical specimens in which the levels of Abeta were below the detection limits of EIA were subjected to Western blot analysis. A fraction of such specimens contained SDS-stable dimer at 6 approximately 8 kd, but not SDS-dissociable A(beta) monomer at approximately 4 kd, as judged from the blot. This A(beta) dimer is unlikely to be generated after death, because (i) specimens with very short postmortem delay contained the A(beta) dimer, and (ii) until 12 hours postmortem, such SDS-stable A(beta) dimer is detected only faintly in PDAPP transgenic mice. The presence of A(beta) dimer in the cortex may characterize the accumulation of A(beta) in the human brain, which takes much longer than that in PDAPP transgenic mice.