| 摘要 |
PURPOSE:To prepare a nuclease having high substrate specificity, which discriminates the DNA of specific species of organisms, and breaks the phosphodiester bond at a specific position of the DNA molecule, by separating and purifying an extract of bacterial cells obtained by the culture of bacteria belonging to Bacillus magaterium. CONSTITUTION:Endonuclease-producing bacteria belonging to Bacillus megaterium, e.g. Bacillus megaterium B-205-3 strain (FERM-P No.3641) are cultured in a nutrient medium at 30-37 deg.C using an aerated and agitated fermentor. The cultured cells are collected between the logarithmic growth phase and the initial stage of the stationary phase, disintegrated, and extracted to obtain a cell-free extract. The extract is purified by the combination of removal of nucleic acid, ammonium sulfate fractionation, ion exchange chromatography, gel filtration, etc. to obtain the objective endonuclease. The enzyme breaks the phosphodiester bonds of Bacillus phage phi105C DNA and Coli phage lambda DNA to DNA fractions having specific lengths. |
