The chromatography of nucleic acid preparations on deae-cellulose paper. III. Study of depolymerization and denaturation processes

Our present results indicate that deoxyribonucleic acid (DNA) preparations of calf thymus origin contain different macromolecular species which can be separated by centrifugal DEAE-cellulose paper pulp (CPP) chromatography. These fractions can be attacked by enzyme action or by heating, and the present paper indicates the relationship between the different macromolecular species. Each fraction appears vulnerable to deoxyribonuclease I, the more highly polymerized ones being attacked first. The hydrolysis products are, in turn, hydrolyzed by the enzyme to smaller molecules. During the melting phenomenon by heat denaturation, the different fractions of lcalf thymus DNA are modified in such a way that they are eluted with eluants 5 and 7. At a given temperature ( when equal or superior to the melting point), the relative importance of the different varies with time. Fraction 5 appears as an end state of the melting process. These results show that the CPP chromatography method can be applied to the study of changes occurring in a pollution of DNA molecules submitted to the action of various physical or biological agents.