PURPOSE: To purify a large amount of circular DNA, by the combination of the use of an enzyme digesting straight-chain DNA and inactive to circular DNA and the technique of column chromatography.
CONSTITUTION: The cells of higher animal or vegetable are suspended in 50mM trishydrochloric acid, and are dissolved by adding a surface active agent to the suspension. The product is subjected to ultracentrifugation, and the supernatant liquid containing crude extract of the cell is separated. The liquid contains circular DNA, single strand DNA and double strand DNA. The liquid is subjected to ion chromatography to remove single strand DNA, and then treated with ATP-dependent nuclease to digest and depolymerize the double strand DNA. The objective circular DNA can be prepared by this process.
TSUDA OSAMU
FUJIMOTO MASAJI
TODA MASAAKI
KATOU KAZUTO
MAEKAWA NOBUHIKO
UMENO MORIO
ANAI MOTOAKI
