NONCOVALENT INTERACTIONS BETWEEN FAB AND FC REGIONS IN IMMUNOGLOBULIN-G MOLECULES - HYDROGEN-DEUTERIUM EXCHANGE STUDIES
NONCOVALENT INTERACTIONS BETWEEN FAB AND FC REGIONS IN IMMUNOGLOBULIN-G MOLECULES - HYDROGEN-DEUTERIUM EXCHANGE STUDIES
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DOI：
10.1111/j.1432-1033.1987.tb10541.x
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发表时间：
1987-01-02
期刊：
影响因子：
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通讯作者：
ZAVODSZKY, P
中科院分区：
文献类型：
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作者：
KILAR, F;ZAVODSZKY, P
为了揭示IgG分子的Fab和Fc区之间的非共价相互作用，使用平均构象自由能变化。图形 **。通过Fab和Fc片段以及完整分子的氢-氘交换来测量与可逆微解折叠相关的蛋白质分子量。在这些实验中使用人单克隆IgG 1和合并IgG样品。以交换弛豫谱的形式对氢氘交换数据进行了总结和比较。实验观察到的完整IgG的弛豫光谱不能通过对Fab和Fc片段测量的光谱进行加权求和来推断。测量数据和计算数据的比较揭示了将IgG分子分裂成两个Fab和Fc片段的构象自由能增加5-kJ/mol，即发生构象迁移率增加。这种变化可以通过完整分子中Fab和Fc片段的相关波动模式或通过接触表面上的屏蔽效应来解释。这两种解释都假设Fab和Fc之间存在非共价相互作用，这可能是识别位点和效应位点之间信息转导的一种方式。氢-氘交换的pH依赖性也表明Fab和Fc区之间的相互作用。在pH 8.2和7.3之间观察到Fab片段的弛豫光谱的偏移，揭示了在较低pH下结构的不稳定。这种效应在完整分子中不存在，反映了稳定Fab结构的相互作用。Fab和Fc的弛豫光谱的比较显示这些片段的微稳定性的差异为约10 kJ/mol：Fab部分比Fc部分具有更多的构象柔性（即其微稳定性更小）。
To reveal non-covalent interactions between the Fab and Fc regions of IgG molecules the average conformational free-energy change .**GRAPHIC**. associated with reversible micro-unfoldings, was measured by hydrogen-deuterium exchange for the Fab and Fc fragments and the complete molecule. Human monoclonal IgG1 and pooled IgG samples were used in these experiments. Hydrogen-deuterium exchange data were summarized and compared in the form of exchange relaxation spectra. The experimentally observed relaxation spectrum of intact IgG could not be deduced by weighted summation of spectra measured for Fab and Fc fragments. A comparison of the measured and calculated data revealed a 5-kJ/mol increase in the conformational free energy uon splitting the IgG molecule into two Fab and Fc pieces, i.e. an increase of conformational mobility occurred. This change can be explained either by related fluctuation patterns of the Fab and Fc pieces in the intact molecule or by a shielding effect on the contact surfaces. Both interpretations suppose non-convalent interactions beween Fab and Fc that can be a means of information transduction between recognition and effector sites. The pH dependence of the hydrogen-deuterium exchange also indicates interactions between the Fab and Fc regions. A shift in the relaxation spectra of the Fab fragment was observed between pH 8.2 and 7.3 revealing destabilization of the structure at lower pH. This effect is absent in the intact molecule, reflecting interactions that stabilize the Fab structure. Comparison of the relaxation spectra of Fab and Fc shows a difference of about 10 kJ/mol in the microstability of these fragments: the Fab part possesses more conformational flexibility (i.e. its microstability is smaller) than the Fc part.