Singh Sanjay K, Suresh Madathilparambil V, Hammond David J, Rusiñol Antonio E, Potempa Lawrence A, Agrawal Alok
Department of Pharmacology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, United States.
Clin Chim Acta. 2009 Aug;406(1-2):151-5. doi: 10.1016/j.cca.2009.06.018. Epub 2009 Jun 21.
The 5 subunits of native pentameric C-reactive protein (CRP) are dissociated to generate the monomeric form of CRP (mCRP) in some in vitro conditions, both physiological and non-physiological, and also in vivo. Many bioactivities of mCRP generated by urea-treatment of CRP and of mCRP generated by mutating the primary structure of CRP have been reported. The bioactivities of mCRP generated by spontaneous dissociation of CRP are largely unexplored.
We purified mCRP generated by spontaneous dissociation of CRP and investigated the binding of mCRP to enzymatically-modified low-density lipoprotein (E-LDL).
mCRP was approximately 60 times more potent than CRP in binding to E-LDL. In the presence of the small-molecule compound phosphoethanolamine (PEt), at 37 degrees C, the binding of mCRP to E-LDL was enhanced <2-fold, while the binding of CRP to E-LDL was enhanced >10-fold. In contrast, PEt inhibited the binding of both CRP and mCRP to pneumococcal C-polysaccharide, another phosphocholine-containing ligand to which CRP and mCRP were found to bind. We have not investigated yet whether PEt alters the structure of CRP at 37 degrees C.
Combined data suggest that the targeting of CRP with the aim to monomerize CRP in vivo may be an effective approach to capture modified forms of LDL.
在一些生理和非生理的体外条件下以及体内，天然五聚体C反应蛋白（CRP）的5个亚基会解离，生成单体形式的CRP（mCRP）。由尿素处理CRP产生的mCRP以及通过改变CRP一级结构产生的mCRP的许多生物活性已见报道。由CRP自发解离产生的mCRP的生物活性在很大程度上尚未被探索。
我们纯化了由CRP自发解离产生的mCRP，并研究了mCRP与酶修饰的低密度脂蛋白（E-LDL）的结合。
mCRP与E-LDL结合的效力约为CRP的60倍。在小分子化合物磷酸乙醇胺（PEt）存在的情况下，在37℃时，mCRP与E-LDL的结合增强不到2倍，而CRP与E-LDL的结合增强超过10倍。相反，PEt抑制了CRP和mCRP与肺炎球菌C多糖的结合，CRP和mCRP都被发现能与肺炎球菌C多糖结合，肺炎球菌C多糖是另一种含磷酸胆碱的配体。我们尚未研究PEt在37℃时是否会改变CRP的结构。
综合数据表明，旨在使体内CRP单体化的靶向CRP方法可能是捕获修饰形式LDL的有效途径。
