[A trial of the enzyme nuclease S1 for the recognition of defects in the secondary structure of DNA].

In order to develop an adequate method for quantitative determination of age-related defects of DNA secondary structure in somatic cells, the testing of enzyme nuclease S1 ("Sigma") was carried out. The conditions have been selected under which this enzyme revealed all single-stranded breaks and did not induce nonspecific breaks in DNA. It was shown that homopurine-homopyridine blocks of DNA capable of changing to H-form hypersensitive to S1, were not detected with the enzyme in the selected conditions.