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The structure of the DNA of bacteriophage φX174: III. Ultracentrifugal evidence for a ring structure

Fiers, Walter and Sinsheimer, Robert L. (1962) The structure of the DNA of bacteriophage φX174: III. Ultracentrifugal evidence for a ring structure. Journal of Molecular Biology, 5 (4). pp. 424-434. ISSN 0022-2836. doi:10.1016/S0022-2836(62)80031-X.

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By velocity sedimentation, in appropriate solvents, the presence of two discrete components can be demonstrated in preparations of the DNA of bacteriophage φX174. The major, faster-moving S_1 and the slower S_2 are present under conditions which exclude the possibility of hydrogen-bond formation. It can be shown, either by treatment with pancreatic deoxyribonuclease or by thermal inactivation, that S_2 is the first degradation product of S_1, formed by scission of S_1, without significant decrease in molecular weight. A subsequent chain scission in S_2, which occurs with equal likelihood, results in random fragmentation. These results are interpreted to mean that the S_1 component is a covalently linked ring structure and the S_2 component is the corresponding open-chain degradation product. Under certain conditions the S_2 component can be selectively degraded by E. coli phosphodiesterase. The digestion is not complete and there appears to be a single discontinuity, resistant to phosphodiesterase, present in the φX-DNA ring.

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Additional Information:© 1962 Elsevier Ltd. Received 20 June 1962. We thank Dr. J. Vinograd for showing us prior to publication his data on the behavior of φX DNA in alkaline solution. Dr. E. Carusi assisted on several occasions with the ultracentrifuge studies. This research was supported by United States Public Health Service Grant RG6965. One of us (W. F.) is a Rockefeller Foundation Fellow; "Charge de Recherches du Fonds National Belge de la Recherche Scientifique".
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U.S. Public Health Service (USPHS)RG6965
Rockefeller FoundationUNSPECIFIED
Issue or Number:4
Record Number:CaltechAUTHORS:20160610-080852481
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Official Citation:Walter Fiers, Robert L. Sinsheimer, The structure of the DNA of bacteriophage φX174, Journal of Molecular Biology, Volume 5, Issue 4, 1962, Pages 424-434, ISSN 0022-2836, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:67808
Deposited By: Ruth Sustaita
Deposited On:10 Jun 2016 16:04
Last Modified:11 Nov 2021 03:54

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