I am going to use plasmid DNA from maxi-prep to transfect cells, so I want the DNA to be as pure as possible. After ethanol precipitation, I often use ddH2O
(not TE or any other buffers) to dissolve pellets. The OD260/OD280 ratio of my preps were sometimes around 1.3-1.4, but another CHCl3 and phenol extraction wouldn't help to improve the results. The interesting thing was that the OD of a certain sample is not constant. One time it could be 1.4, and the next time it would be 1.8. It is rather weired. I heard people saying that DNA in H2O ( not buffered solution) can be strange, but I don' t want to use TE or EB buffer to solve DNA because I worried that these buffers would affect the efficiency of transfection. Is there any other way to monitor the quality of DNA in ddH2O?
Another thing is that I use OD260 to decide the concentration of DNA. If it is not accurate in ddH20, how can I know the concentration?
Edited by felixwang, 30 March 2005 - 07:51 AM.