Leng M, Guigues M, Genest D
Biochemistry. 1978 Aug 8;17(16):3215-20. doi: 10.1021/bi00609a007.
Interactions between antibodies to poly(inosinic acid).poly(cytidylic acid) [poly(I).poly(C)] (or Fab fragments) and double-stranded polynucleotides have been studied by several techniques. In quantitative precipitation tests, the amounts of precipitated antibodies depend upon salt concentration. This effect of salt is reversible. From the comparison of the association constants (deduced from fluorescence measurements) for the binding of Fab fragments to several polynucleotides, a direct interaction between atoms or groups of the bases, which can be involved in hydrogen bonds, can be excluded. The complexes between poly(I).poly(C) and Fab fragments interact with ethidium bromide. The association constants for the binding of ethidium bromide to poly(I).poly(C) and to poly(I).poly(C)-Fab fragments complexes are about the same, but Fab fragments reduce the number of base pairs available to ethidium bromide binding. At saturation of poly(I).poly(C) by Fab fragments, the number of binding sites of ethidium bromide is only reduced by a factor of two. It is concluded that all the nucleotide residues covered by the Fab fragment binding site do not interact with the amino acid residues. Circular dichroism studies of the complexes between Fab fragments and polynucleotides are in favor of some conformational change of the polynucleotides.
已通过多种技术研究了聚肌苷酸-聚胞苷酸[聚（I）·聚（C）]抗体（或Fab片段）与双链多核苷酸之间的相互作用。在定量沉淀试验中，沉淀抗体的量取决于盐浓度。盐的这种作用是可逆的。通过比较Fab片段与几种多核苷酸结合的缔合常数（由荧光测量推导得出），可以排除碱基的原子或基团之间可能参与氢键形成的直接相互作用。聚（I）·聚（C）与Fab片段之间的复合物与溴化乙锭相互作用。溴化乙锭与聚（I）·聚（C）以及聚（I）·聚（C）-Fab片段复合物结合的缔合常数大致相同，但Fab片段减少了可用于溴化乙锭结合的碱基对数量。当Fab片段使聚（I）·聚（C）饱和时，溴化乙锭的结合位点数量仅减少一半。由此得出结论，Fab片段结合位点覆盖的所有核苷酸残基均不与氨基酸残基相互作用。对Fab片段与多核苷酸之间复合物的圆二色性研究表明多核苷酸发生了一些构象变化。
