Enzymic degradation of deoxyribonucleic acid. II. Enzymic properties of thymus acid deoxyribonuclease.
Abstract The degradation of deoxyribonucleic acid by thymus acid deoxyribonuclease was studied by viscosity, formation of acid-soluble products, spectrophometry, and pH measurements. The influence of enzyme and substrate concentration is examined. Divalent cations, Mg, Mn, Ca and Zn are activators at low concentrations and inhibitors at higher ones. There is a stoichiometric relationship between the concentrations of substrate and cations at the point of maximum activation. Spectral changes and pH variation are discussed in relation with structural modifications of the degradation products. From the viscometric experiments, the mechanisms of action of the two DNases (neutral and acid) appear to be quite different.