title: Temperature dependent structural changes of intraphage T7 DNA.
abstract: The phenomena connected with the first phase transition step of the native T7 phage at 40 degrees-65 degrees 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 degrees-65 degrees 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.
mesh_terms: D004279:DNA, Viral; D006358:Hot Temperature; D008433:Mathematics; D009690:Nucleic Acid Conformation; D012542:Scattering, Radiation; D013053:Spectrophotometry; D013604:T-Phages / Q000032:analysis*; D014965:X-Rays
chemical_list: D004279:DNA, Viral