[Effect of UV-light on the structure of soluble deoxyribonucleoprotein-200 A].

The effects of UV-light (253,7 nm) on the structure of DNP and its protein and nucleic components were studied. The formation of protein-DNA covalent bonds in DNP-200 A at low ionic strength was confirmed. Under certain irradiation conditions more than 80% of protein may be linked to the DNA; all histone fractions were linked to the same extent and at the same rates. The local denaturation of DNA in the region of photo-induced thymine-thymine dimers and other photoadducts dramatically changed the rate and specificity of the effects of staphylococcal nuclease, which directly affected the composition and size of the fragments formed. A possible application of UV-irradiated DNP for various structural investigations is discussed.