Small angle neutron scattering studies of C8 and C9 and their interactions in solution.
Small angle neutron scattering studies of C8 and C9 and their interactions in solution.
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C8 和 C9 的小角中子散射研究及其在溶液中的相互作用。
DOI：
10.1016/s0006-3495(93)81434-6
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发表时间：
1993
影响因子：
3.4
通讯作者：
Zaccai,G
中科院分区：
文献类型：
--
作者：
Esser,AF;Thielens,NM;Zaccai,G
小角中子散射（SANS）结果表明，与大多数报道相反，C9不是球状蛋白。在pH为8，离子强度为0.5时，其旋转半径（Rg）为32.2 +/- 1.4 A，生理离子强度为35 A。相比之下，质量大2.2倍的C8具有相似的Rg值[34.6 +/- 1.6 a]。Rg与M(r)的校正图表明，原生C8是一个球形蛋白，而原生C9是细长的。从以前的报道中得知，原生C8和C9在低离子强度的溶液中缔合。SANS结果证实了这一观察结果，但也表明C8-C9异源二聚体已经在生理离子强度下形成。二聚体复合物呈球形[Rg = 40 +/- 0.8 A]，表明蛋白质是肩并肩而不是端到端结合的。相反，当药物苏拉明（一种有效的C5b-9复合物组装抑制剂）存在时，C9形成的复合物的分子质量是C5b-9复合物的两倍，但仍被延长（Rg = 48.8 +/- 0.8 a），这表明在这种情况下，蛋白质通过桥接苏拉明分子端到端进行二聚化。
Small angle neutron scattering (SANS) results revealed that contrary to most reports C9 is not a globular protein. Its radius of gyration (Rg) at pH 8 and an ionic strength of 0.5 is 32.2 +/- 1.4 A increasing to 35 A at physiologic ionic strength. In contrast, C8, which has a 2.2-fold larger mass, has a similar Rg value [34.6 +/- 1.6 A]. Calibration plots of Rg vs. M(r) indicate that native C8 is a spherical protein whereas native C9 is elongated. From previous reports it was known that native C8 and C9 associate in solutions of low ionic strength. SANS results confirmed this observation but also demonstrated that C8-C9 heterodimers are already formed at physiologic ionic strength. The dimeric complex is globular [Rg = 40 +/- 0.8 A] indicating that the proteins associate side-by-side rather than end-to-end. In contrast, in presence of the drug Suramin, a potent inhibitor of the assembly of the C5b-9 complex, C9 forms a complex with twice the molecular mass that is still elongated (Rg = 48.8 +/- 0.8 A), suggesting that in this case the protein dimerizes end-to-end via a bridging Suramin molecule.