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Studies on Chromatin. Free DNA in Sheared Chromatin

Varshavsky, Alexander J. and Bakayev, Valery V. and Ilyin, Yurii V. and Bayev, Alexey A., Jr. and Georgiev, Georgii P. (1976) Studies on Chromatin. Free DNA in Sheared Chromatin. European Journal of Biochemistry, 66 (2). pp. 211-223. ISSN 0014-2956. https://resolver.caltech.edu/CaltechAUTHORS:20201216-124002591

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Abstract

Chromatin which has been hydrodynamically sheared in a low‐ionic‐strength buffer lacking divalent cations (I = 0.005 M) contains a heterogeneous set of deoxyribonucleoprotein particles but no molecules of free DNA. The main finding is that a transference of sheared chromatin to 1–2 mM MgCl₂ or to 0.1–0.2 M NaCl results in appearance of completely free DNA molecules. A salt‐induced rearrangement of DNA‐bound histories but not a partial loss of them is responsible for the observed phenomenon. Formation of free DNA molecules is accompanied by aggregation of the majority of remaining deoxyribonucleoprotein particles. The percentage of free DNA molecules in the chromatin which was sheared to an average DNA length of about 400 base pairs is increased from zero in the initial sample to 8–9% in 1 mM MgCl₂ and further to ∼ 25% of the total DNA in 0.15 M NaCl, 2 mM MgCl₂. Free DNA molecules in the sheared chromatin are observed not only upon isopycnic banding of formaldehyde‐fixed deoxyribonucleoproteins in CsCl gradients but also in non‐ionic metrizamide gradients with either fixed or unfixed deoxyribonucleoprotein samples. The process of free DNA formation is a reversible one; its direction and the equilibrium state depend in particular on the ionic conditions of the medium.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1111/j.1432-1033.1976.tb10510.xDOIArticle
ORCID:
AuthorORCID
Varshavsky, Alexander J.0000-0002-4011-258X
Additional Information:© 1976 Federation of European Biochemical Societies. (Received January 14/April 5, 1976) We thank A. A. Melnickov and N. N. Dobbert for their expert technical assistance.
Issue or Number:2
Record Number:CaltechAUTHORS:20201216-124002591
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20201216-124002591
Official Citation:VARSHAVSKY, A.J., BAKAYEV, V.V., ILYIN, Y.V., BAYEV, A.A., Jr and GEORGIEV, G.P. (1976), Studies on Chromatin. Free DNA in Sheared Chromatin. European Journal of Biochemistry, 66: 211-223. https://doi.org/10.1111/j.1432-1033.1976.tb10510.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107127
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:16 Dec 2020 21:30
Last Modified:16 Dec 2020 21:30

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