Temperature dependent structural changes of intraphage T7 DNA |
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Authors: | A Fekete Gy Rontó L A Feigin V V Tikhonychev K Módos |
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Institution: | (1) Institute of Biophysics, Semmelweis Medical University, P.O. Box 263, H-1444 Budapest, Hungary;(2) Institute of Crystallography, Academy of Sciences of the USSR, SU-117333 Moscow, USSR;(3) Department of Physics, Moscow State University, SU-117234 Moscow, USSR |
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Abstract: | The phenomena connected with the first phase transition step of the native T7 phage at 40 C–65 C have been studied using various methods. In this temperature range a) the optical melting curve shows an absorption decrease, b) the maximum of the small-angle X-ray scattering characteristic for DNA packing disappears, c) there is a drop of biological activity and d) there are changes in the structure of the difference absorption spectra of native phages versus isolated DNA. All data are interpreted assuming a structural change of the DNA due to the release of its protein coat towards the end of the first phase transition step (at 60 –65 C in the case of M9 buffer). Above this temperature the intraphage DNA packing appears to be destroyed and the DNA structure seems to be similar to that in DNA solution. |
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Keywords: | Bacteriophages Phase transition Optical melting curve X-ray scattering |
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