Potempa L A, Gewurz H
Mol Immunol. 1983 May;20(5):501-9. doi: 10.1016/0161-5890(83)90088-3.
C-reactive protein (CRP) is a trace serum protein which elevates up to 1000-fold in concentration in association with inflammation and tissue necrosis. CRP binds with phosphocholine and phosphate esters; initiates reactions of agglutination, opsonization and complement consumption; and precipitates with protamine and synthetic polymers of lysine and arginine, and these reactivities are modulated by calcium and phosphocholine. We now report on the interactions of heparin with these polycations in the absence and presence of CRP, which show marked similarities to reactions between antigen and antibody. Heparin optimally precipitated with the polycations over a narrow range of reactant ratios, peaking at slight anion charge excess. The complexes formed did not dissociate in excess heparin: however, complex formation was significantly depressed when heparin was added in a single dose in excess of the amount required for optimal precipitation. Calcium did not affect the precipitation of heparin with polycation, and heparin did not precipitate with CRP. However, heparin did induce a rapid and efficient dissociation of CRP-polycation precipitates preformed at equivalence, with total release of CRP. Small amounts of heparin augmented precipitation under conditions of polycation excess of CRP, but as heparin levels were increased to amounts needed to reach equivalence with polycation, CRP was resolubilized in favor of the preferred heparin-polycation complexes. Chondroitin sulfate was similar to heparin in its effects upon the CRP-poly-L-arginine (PLA) interaction, while hyaluronic acid enhanced CRP-PLA precipitation at all concentrations tested and DNA had neither augmenting nor solubilizing effects. These data indicate that CRP-polycation interactions are significantly and selectively influenced in the presence of small amounts of heparin and certain other polyanions. This modulatory reactivity may be of importance in the biological reactivities of CRP during episodes of acute inflammation.
C反应蛋白（CRP）是一种微量血清蛋白，在炎症和组织坏死时其浓度可升高至1000倍。CRP与磷酸胆碱和磷酸酯结合；引发凝集、调理吞噬和补体消耗反应；并与鱼精蛋白以及赖氨酸和精氨酸的合成聚合物沉淀，这些反应活性受钙和磷酸胆碱调节。我们现在报告肝素在有无CRP存在的情况下与这些聚阳离子的相互作用，其显示出与抗原和抗体之间反应的显著相似性。肝素在狭窄的反应物比例范围内与聚阳离子最佳沉淀，在轻微阴离子电荷过量时达到峰值。形成的复合物在过量肝素中不会解离：然而，当以超过最佳沉淀所需量的单剂量添加肝素时，复合物形成会显著受到抑制。钙不影响肝素与聚阳离子的沉淀，且肝素不与CRP沉淀。然而，肝素确实能诱导在等当量时预先形成的CRP - 聚阳离子沉淀物快速有效解离，使CRP完全释放。在聚阳离子过量于CRP的条件下，少量肝素会增强沉淀，但随着肝素水平增加到与聚阳离子达到等当量所需的量时，CRP会重新溶解以利于形成优选的肝素 - 聚阳离子复合物。硫酸软骨素对CRP - 聚L - 精氨酸（PLA）相互作用的影响与肝素相似，而透明质酸在所有测试浓度下均增强CRP - PLA沉淀，DNA既无增强作用也无溶解作用。这些数据表明，在存在少量肝素和某些其他聚阴离子的情况下，CRP - 聚阳离子相互作用受到显著且选择性的影响。这种调节反应性在急性炎症发作期间CRP的生物学反应中可能很重要。
