Biochemical and ultrastructural analysis of SV40 chromatin

Keller, W. and Müller, U. and Eicken, I. and Wendel, I. and Zentgraf, H.. (1978) Biochemical and ultrastructural analysis of SV40 chromatin. Cold Spring Harbor Symposia on Quantitative Biology, 42. pp. 227-244.

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Official URL: http://edoc.unibas.ch/dok/A5258010

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SV40 chromatin can be isolated in two forms: At moderate ionic strength (mu = 0.1-0.3) it contains histone H1 in addition to the four nucleosomal histones and has a highly condensed appearance in the electron microscope, being composed of a few closely connected large spheres [190 A (160, 220) diameter]. At high ionic strength (mu = 0.6-0.8) or after prolonged exposure to very low ionic strengths (mu less than 0.02), the compact form unfolds and the chromatin shows a typical nucleosomal morphology. Native SV40 DNA-protein complexes contain a median number of 24 nucleosomes. The number of superhelical turns does not differ in DNA obtained from the compact and the unfolded forms of chromatin. DNA-relaxing enzyme is found associated with SV40 chromatin and is capable of acting both on extraneously added circular DNA and on its own DNA in the nucleoprotein complex. Purified DNA-relaxing enzyme forms transiently nicked DNA intermediates where the enzyme can be found covalently attached to the site of the nick in the DNA. Transcriptionally active SV40 complexes undergo the same ionic-strength-dependent structural transition as that of bulk SV40 chromatin and may therefore also have a compact configuration at physiological salt concentrations.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Former Organization Units Biozentrum > Cell Biology (Keller)
UniBasel Contributors:Keller, Walter
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Cold Spring Harbor Laboratory Press
Note:Also published in: Chromatin. - New York : Cold Spring Harbor Laboratory, 1978. - Part 1, S. 227-244 -- Publication type according to Uni Basel Research Database: Journal article
Last Modified:07 Nov 2017 13:34
Deposited On:22 Mar 2012 13:59

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