Plasmid deoxyribonucleic acid (DNA) was tightly bound to cells of Escherichia coli at 0 degrees C in the presence of divalent cations. During incubation at 42 degrees C, 0.1 to 1% of this DNA became resistant to deoxyribonuclease. Deoxyribonuclease-resistant DNA binding and the ability to produce transformants became saturated when transformation mixtures contained 1 to 2 micrograms of plasmid ...

Recombinant human deoxyribonuclease (rhDNase) is an agent which reduces the viscoelasticity of purulent sputum. Two cases are reported in which rhDNase was utilised for the management of lobar atelectasis due to retained purulent secretions.

The observation of Boman and Kaletta (I, 2) that venom phosphodiesterase is capable of hydrolyzing the so called native thymus deoxyribonucleic acid has been confirmed in several laboratories (3-5). Boman (6) noticed that under appropriate conditions the reaction may be carried almost to completion. All these experiments were performed with comparatively crude preparations of phosphodiesterase....

The activity of ribonuclease increases with increasing concentration of added divalent metal ions until the attainment of an optimal metal concentration, beyond which the addition of further metal ions inhibits the reaction. When either the optimal metal concentration or the enzymatic activity at that concentration is plotted versus the atomic number of the transition metals, the resulting curv...