期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1978
卷号：75
期号：2
页码：660-663
DOI：10.1073/pnas.75.2.660
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Hydrodynamic studies on monomer chromatin subunits (v1) as a function of ionic strength (0.7 mM to 100 mM KCl) indicate two salt-dependent conformational transitions. An abrupt transition occurs at about 7.5 mM ionic strength. Decreasing the ionic strength from 10 to 5 mM results in a decrease in s20,w of the v1 from 11.1 to 9.9 S. The diffusion coefficient D20,w decreases from 3.3 to 2.7 X 10(-7) cm2 sec--1. The v1 crosslinked with formaldehyde at 10 mM ionic strength do not undergo a similar salt-dependent change in s20,w. Another transition is observed at about 1 mM ionic strength; s20,w decreases to 9.4 S and D20,w decreases to 2.2 X 10(-7) cm2 sec--1. Throughout the entire salt range the molecular weight of the v1 remains reasonably constant, implying that salt-dependent changes in the frictional coefficient are being observed. Various hydrodynamic models are considered as possible interpretations of the observed changes in the frictional coefficient.
