RESUMO
Fractions of acid and base blood serum proteins, separated by ion exchange chromatography on QAE-Sephadex (but not the proteins of the whole blood serum, which had the same charge), reacted with DNA preparations. Separate fractions of blood serum proteins were able to react with DNA after electrophoretic separation. Binding of blood serum proteins with DNA did not depend on ion strength within the range of NaCl concentration from 0.1 M to 0.5 M; it was also stable at pH 5.5 = 8.0. Interaction between acid DNA-binding proteins and native DNA was inhibited by denatured DNA, polyguanilic and polyinosinic acids and by other polyanions: dextran sulfate, polyvinyl sulfate, polyanetol sulphonate, polystyrol sulphonate and heparin. Acid DNA-binding proteins showed only a slight affinity to polyadenilic, polyuridilic and polycytidilic acids. The acid and base DNA-binding proteins appear to be contained in blood serum in the form of a loosely bound complex.
