PEG-Plasmid-Max-Prep Precipitation

PEG-Plasmid-Max-Prep(compare PEG/NaCl/MgCl₂ with PEG/CaCl₂)

Reference to the protocol: PEG-Plasmid-Max-Prep.

Grow STB3 transformed with clone 303 in 2 flasks (500 ml) of LB/AMP. Precipitate with CTAB, then dissolve DNA in 0.75M NaCl, precipitate with PEG/NaCl/MgCl₂ or PEG/CaCl₂

I.Purity by OD260/280

Sample	OD260/280	Concentration
1. PEG/NaCl/MgCl2	1.89	1474.5ng/ul
2. PEG/NaCl/MgCl2	1.90	762.5ng/ul
1. PEG/CaCl2	1.87	962.8ng/ul
2. PEG/CaCl2	1.83	237.7ng/ul

1----the first time to dissolve DNA with water;

2----the second time to dissolve DNA with water;

II.Run Argrose Gel.

1 and 2 are the plasmid extracted by PEG/CaCl2, which does not have RNA;

3 and 4 are the plasmid extracted by PEG/NaCl/ MgCl_2, which has the trace of RNA;

According to I and II, PEG/CaCl₂ is good. So we can make sure that using PEG/CaCl₂ to extract DNA for Maxi Prep should be better.

 --Ruili.su 14:51, 14 September 2011 (EST)