FIELD : medicine.SUBSTANCE : proposed group of inventions relates to medicine. Proposed are a method for detecting a modified base in a double-stranded nucleic acid molecule and a method for identifying at least one compound capable of preventing the interaction of a protein with its binding site. At first, the double-stranded nucleic acid molecule is denatured, then it is renatured in the presence of a protein capable of binding to the modified base. Next, blockage of the renaturation of the double-stranded nucleic acid is detected and the position of said blockage in the double-stranded nucleic acid molecule is determined.EFFECT : proposed group of inventions provides for the identification of various DNA modifications and the determination of DNA-protein binding by determining the position at which blockage occurs.14 cl, 13 dwg