The Nuclease Activity of Bacillus Subtilis

Nuclease activity was dissociated from proteolytic activity when Sachs confirmed the observations of Milroy that an agent which attacked nucleic acid to liberate inorganic phosphoric acid could not liquefy gelatin and that proteolytic enzymes liquefied gelatin but could not attack nucleic acid (1). Henceforth the rate of separation of inorganic phosphoric acid from nucleic acid became the exclusive index of nuclease activity (24). Activity so defined was shown by a variety of microorganisms, such as yeast (5), Penicillium qlaucum, and Asperqillus niqer (6), and by Bacillus coli, Bacillus proteus, and staphylococcus (7). Convincing evidence of bacterial disintegration of nucleic acid other than the slow separation of phosphoric acid has been lacking despite the discovery of a series of enzymes which can attack the different components of nucleic acid: thus there are polynucleotidases which subdivide nucleic acid to nucleotides,l nucleotidases which split mononucleotides to phosphoric acid and nucleosides, nucleosidases which disjoin the sugar and nitrogenous base, and phosphatases which split phosphoric acid esters of ribose to free acid and free sugar ((8) pp. 311-316). Furthermore, the accepted structural formula of yeast nucleic acid, that elucidated by Levene and Bass ((8) p. 274, 286) indicates that the separation of more than one-quarter of the phosphoric acid in nucleic acid requires the breaking of the ester bonds between its component nucleotides. It is apparent also that these ester bonds may be broken without the separation of phosphoric acid from any of the four nucleotides