Finch J T, Klug A
Proc Natl Acad Sci U S A. 1976 Jun;73(6):1897-901. doi: 10.1073/pnas.73.6.1897.
Chromatin prepared by brief digestion of nuclei with micrococcal nuclease, and extracted in 0.2 mM EDTA, appears in the electron microscope as filaments of about 100 A diameter which coil loosely. In 0.2 mM Mg++ these "nucleofilaments" condense into a supercoil or solenoidal structure of pitch about 110 A corresponding to the diameter of a nucleofilament. It is proposed that the x-ray reflections at orders of 110 A observed in chromatin originate in the spacing between turns of the solenoid rather than that between nucleosomes along the nucleofilament. The solenoidal structure appears to need histone H1 for its stabilization. Under certain conditions, isolated nucleosomes can also aggregate into a similar structure. The solenoidal structure can be correlated with the "thread" of diameter about 300 A observed by other workers in nuclei.
用微球菌核酸酶对细胞核进行短暂消化制备的染色质，在0.2 mM EDTA中提取后，在电子显微镜下呈现为直径约100埃的细丝，这些细丝松散地盘绕着。在0.2 mM Mg++中，这些“核细丝”凝聚成螺距约110埃的超螺旋或螺线管结构，这与核细丝的直径相对应。有人提出，在染色质中观察到的110埃级次的X射线反射起源于螺线管各匝之间的间距，而不是沿着核细丝的核小体之间的间距。螺线管结构似乎需要组蛋白H1来稳定。在某些条件下，分离的核小体也能聚集成类似的结构。螺线管结构可以与其他研究人员在细胞核中观察到的直径约300埃的“细丝”相关联。
