Binding of Ca2+, Mg2+, and heparin by human serum amyloid P component in affinity capillary electrophoresis
Binding of Ca2+, Mg2+, and heparin by human serum amyloid P component in affinity capillary electrophoresis
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DOI：
10.1002/elps.200600005
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发表时间：
2006-07-01
期刊：
影响因子：
2.9
通讯作者：
Blomberg, Lars G.
中科院分区：
文献类型：
--
作者：
Heegaard, Niels H. H.;He, Xinya;Blomberg, Lars G.
人血清淀粉样蛋白P组分（SAP）是一种在血液中循环的糖蛋白，与迄今为止研究的所有类型的淀粉样蛋白（折叠不良的蛋白聚集体）相关。尽管SAP在体内的精确功能的不确定性，这种钙离子激活的蛋白质的凝集素样的性质与阴离子亲和性和错误折叠的蛋白质是众所周知的。在溶液中形成同聚五聚体或十聚体的倾向和在Ca2+存在下的自聚集以及SAP附着到未涂覆的熔融石英上的倾向已经排除了通过微电泳方法对SAP进行分析。我们现在制定条件，以表征结合的Ca 2+和Mg 2+和肝素结合SAP在二价金属离子的存在下，通过ACE。结果表明，即使在低离子强度，pH值8.2的Ca2+的束缚肝素（亚μ M表观解离常数）的强结合。此外，与Mg 2+相比，与Ca 2+的选择性相互作用被证明。该方法将进一步使用微电泳方法来研究SAP与假定的病理生理相关配体（如脂多糖和错误折叠蛋白）的相互作用。
Human serum amyloid P component (SAP) is a glycoprotein circulating in the blood and found in association with all types of amyloid (malfolded potein aggregates) examined so far. Despite uncertainties regarding the precise function of SAP in vivo, the lectin-like properties of this Ca2+-activated protein with affinity for anionic saccharides and malfolded proteins are well known. The propensity to form homomeric penta- or decamers in solution and the selfaggregation in the presence of Ca2+ as well as the tendency of SAP to attach to uncoated fused silica have precluded the analysis of SAP by microelectrophoretic methods. We now work out conditions to characterize the binding of Ca2+ and Mg2+ and the binding of heparin to SAP in the presence of divalent metal ions by ACE. The results show a strong binding of heparin (sub-mu M apparent dissociation constants) even in the abscence of Ca2+ at low ionic strength, pH 8.2. Also, a selective interaction with Ca2+ compared with Mg2+ is demonstrated. The approach will further the use of microelectrophoretic methods to examine the interactions of SAP with ligands of putative pathophysiological relevance such as lipopolysaccharides and misfolded proteins.