High efficiency method to obtain supercoiled DNA with a commercial plasmid purification kit.
Supercoiled state corresponds to the active form for plasmid applications. The relaxed circular form of plasmids is often inactive or poorly active. To obtain significant amounts of almost  fully supercoiled DNA, we modified the standard protocol of a commercially available Qiagen plasmid purification kit. Our changes led to isolation of almost 100% of the plasmids in the supercoiled state. The modified protocol was used to purify different plasmids with consistent results. The purified plasmids maintain supercoiled state for about two months. The modified protocol is very advantageous because it allows easy DNA production with high degree of supercoiled form at low cost.
University of Naples Federico II, Department of Structural & Functional Biology, NAPLES, Italy.
Antonietta
A
Carbone
Flavia Marialucia
FM
Fioretti
Laura
L
Fucci
Juan
J
Ausió
Marina
M
Piscopo
D002852:Chromatography, Ion Exchange; D015925:Cryopreservation; D004269:DNA, Bacterial / Q000302:isolation & purification*; D004278:DNA, Superhelical / Q000302:isolation & purification*; D004926:Escherichia coli / Q000235:genetics*; D010957:Plasmids / Q000302:isolation & purification*; D013696:Temperature
D004269:DNA, Bacterial; D004278:DNA, Superhelical