Inoko Y, Yamamoto M, Fujiwara S, Ueki T
Department of Biophysical Engineering, Faculty of Engineering Science, Osaka University.
J Biochem. 1992 Mar;111(3):310-6. doi: 10.1093/oxfordjournals.jbchem.a123755.
The structure of the DNA region in rat thymus nucleosome core particle has been studied by synchrotron X-ray scattering analysis and the contrast-variation technique has been applied to determine the contribution of the DNA to the total scatterings. Small-angle contrast-matching measurements show that the entire core particle and isolated histone octamers are contrast-matched by solvents containing 64 and 54% (w/w) sucrose, respectively. At a contrast of 54% sucrose, where the scattering of the DNA dominates, the scattering data extending to higher angle of about 0.05 A-1 have been collected from relatively concentrated solutions (10 mg/ml) of core particles and interpreted on the basis of the regular helical model for the DNA region. The model calculations show that the shape of the DNA around the histone core is approximately by 1.8 turns of regular helix of 42 A radius and 28 A pitch. These values for helical parameters of our model are in good agreement with those of the structure of DNA in crystallized nucleosome cores shown by earlier diffraction studies.
通过同步辐射X射线散射分析研究了大鼠胸腺核小体核心颗粒中DNA区域的结构，并应用对比变化技术来确定DNA对总散射的贡献。小角对比匹配测量表明，整个核心颗粒和分离的组蛋白八聚体分别被含有64%和54%（w/w）蔗糖的溶剂对比匹配。在54%蔗糖的对比度下，此时DNA的散射占主导，已从相对浓缩的核心颗粒溶液（10 mg/ml）中收集了延伸至约0.05 Å-1更高角度的散射数据，并基于DNA区域的规则螺旋模型进行了解释。模型计算表明，组蛋白核心周围DNA的形状近似为半径42 Å、螺距28 Å的规则螺旋的1.8圈。我们模型的这些螺旋参数值与早期衍射研究显示的结晶核小体核心中DNA结构的参数值高度一致。
