天然人血清淀粉样蛋白P成分是一种单一的五聚体。

Native human serum amyloid P component is a single pentamer.

作者信息

Sørensen I J, Andersen O, Nielsen E H, Svehag S E

机构信息

Department of Medical Microbiology, Odense University, Denmark.

出版信息

Scand J Immunol. 1995 Mar;41(3):263-7. doi: 10.1111/j.1365-3083.1995.tb03562.x.

DOI:10.1111/j.1365-3083.1995.tb03562.x

PMID:7871385

Abstract

Serum amyloid P component (SAP) and C-reactive protein (CRP) are members of the pentraxin protein family. SAP is the precursor protein to amyloid P component present in all forms of amyloidosis. The prevailing notion is that SAP in circulation has the form of a double pentameric molecule (decamer) whereas CRP is a single pentameric molecule. We have investigated by gel permeation chromatography the M(r) of SAP in freshly collected human serum and of SAP purified by carbohydrate affinity chromatography and anion exchange chromatography. SAP was monitored by quantitative immunoelectrophoresis and ELISA, and SAP peak fractions were analysed by use of SDS-PAGE, Western blotting, and electron microscopy. The results indicate that native SAP circulates as a single pentamer, a part of which forms complexes with C4b-binding protein. The properties of SAP changed during purification as indicated by rocket immunoelectrophoresis and electron microscopy. Thus, electron micrographs of purified SAP showed a predominance of decamers. However, the decamer form of SAP reversed to single pentamers when purified SAP was incorporated into SAP-depleted serum.

摘要

血清淀粉样蛋白P成分（SAP）和C反应蛋白（CRP）是五聚体蛋白家族的成员。SAP是所有形式淀粉样变性中存在的淀粉样蛋白P成分的前体蛋白。普遍的观点是，循环中的SAP具有双五聚体分子（十聚体）的形式，而CRP是单个五聚体分子。我们通过凝胶渗透色谱法研究了新鲜采集的人血清中SAP的相对分子质量（M(r)）以及通过碳水化合物亲和色谱法和阴离子交换色谱法纯化的SAP的M(r)。通过定量免疫电泳和酶联免疫吸附测定（ELISA）监测SAP，并使用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）、蛋白质印迹法和电子显微镜分析SAP峰级分。结果表明，天然SAP以单个五聚体形式循环，其中一部分与C4b结合蛋白形成复合物。如火箭免疫电泳和电子显微镜所示，SAP的性质在纯化过程中发生了变化。因此，纯化的SAP的电子显微照片显示十聚体占优势。然而，当将纯化的SAP掺入不含SAP的血清中时，SAP的十聚体形式转变为单个五聚体。