Miniprep purification of DNA
MINIPREP (2mL) Procedure for Plasmid DNA Purification
(using the QIAGEN QIAPrep Spin Miniprep kit)
!!!!! Make sure Ethanol has been added to the PE Buffer !!!!!
!!!!! Make sure that RNAse has been added to the P1 Buffer !!!!!
- Pellet 2 mL saturated culture by spinning full speed, 30 seconds in a 2mL Microcentrifuge tube.
- Dump supernatant
- Add 250uL of P1 buffer into each tube. Resuspend the cells thoroughly
- Add 250uL of P2 buffer (a base that denatures everything and causes cells to lyse). Gently mix up and down. Solution should become clearer.
- Add 350uL of N3 buffer (an acid of pH ~5 that causes cell junk - including protein and chromosomal DNA - to precipitate, and leaves plasmids and other small molecules in solution). Slowly invert a few times, then shake.
- Spin in centrifuge at top speed for 5 minutes.
- Label blue columns with an alcohol-resistant lab pen.
- Pour liquid into columns, and place the columns into the centrifuge. Spin at full speed for 15 seconds.
- Dump liquid out of the collectors under the columns (the DNA should be stuck to the white resin)
- Wash each column with 500 uL of PB buffer.
- Spin in centrifuge at full speed for 15 seconds, then flick out the liquid again.
- Wash with 750uL of PE buffer (washes the salts off the resins).
- Spin in centrifuge at full speed for 15 seconds and flick out liquid again.
- Spin in centrifuge at full speed for 90 sec to dry off all water and ethanol.
- Label new Microcentrifuge tubes and put columns in them.
- Elute them by adding 50uL of water down the middle of the column (don't let it stick to the sides).
- Spin in centrifuge at top speed for 30 seconds.
- Take out columns and cap the tubes.
- Clean up - note the P1 buffer is stored at 4degC and all the rest at room temperature.