Khokhlov D N, Brusov R V, Grokhovskiĭ S L, Zhuze A L, Surovaia A N, Gurskiĭ G V
Mol Biol (Mosk). 1994 Jan-Feb;28(1):87-95.
Synthesis, DNA- and zinc ion-binding activities of the synthetic 23-residue peptide, forming a part of the DNA-binding domain of yeast transcription activator GAL-4, are reported. In presence of zinc ions considerable changes in the shapes of the fluorescence and CD spectra of the peptide are observed. It is shown that the peptide forms complexes with zinc ions containing one metal ion per peptide molecule with association constants on the order of (1-2) x 10(6) M-1. Using gel filtration on a TSK-gel column we have shown that in aqueous solution at concentrations of 10(-4)-10(-6) M the peptide exists predominantly in the dimeric form. Dimerization constants were found to be 5 x 10(6) M-1 and 1.7 x 10(7) M-1 in the absence and in the presence of zinc ions, respectively. It is shown that the peptide binds to DNA. The binding approaches saturation when one peptide molecule is bound approximately to five base pairs of DNA. The shapes of the titration curves obtained from binding of the peptide to DNA show that the peptide can bind to DNA both in the monomeric and self-associated forms (dimer or tetramer). Increasing DNA concentration and decreasing the peptide/DNA molar ratio lead to a shift in the equilibria between self-associated peptide species and monomers toward the formation of monomer peptide complexes.
报道了构成酵母转录激活因子GAL-4 DNA结合结构域一部分的23个残基合成肽的合成、DNA结合活性和锌离子结合活性。在锌离子存在下，观察到该肽的荧光光谱和圆二色光谱形状发生了显著变化。结果表明，该肽与锌离子形成复合物，每个肽分子含有一个金属离子，缔合常数约为(1-2)×10⁶ M⁻¹。通过在TSK凝胶柱上进行凝胶过滤，我们发现，在浓度为10⁻⁴-10⁻⁶ M的水溶液中，该肽主要以二聚体形式存在。在不存在和存在锌离子的情况下，二聚化常数分别为5×10⁶ M⁻¹和1.7×10⁷ M⁻¹。结果表明，该肽能与DNA结合。当一个肽分子与大约五个DNA碱基对结合时，结合接近饱和。从该肽与DNA结合得到的滴定曲线形状表明，该肽既能以单体形式也能以自缔合形式(二聚体或四聚体)与DNA结合。DNA浓度的增加和肽/DNA摩尔比的降低导致自缔合肽物种和单体之间的平衡向单体肽复合物的形成方向移动。
