high 260/280 ratio after maxiprep - (Jun/24/2008 )

Hi everyone, I did a maxiprep and I want to use the sample for mammalian transfection. My 260 reading shows a concentration of 2.4ug/ul, I measured the 260/280 OD ratio and it is 1.91. If pure DNA is 1.8 and pure RNA is 2.0, does this mean that I have a too much RNA in my sample?

I looked into the manuals of some maxiprep kits and they say that you would expect a 260/280 ratio ~1.98!!! I have no idea why would you expect such a high ratio form a maxiprep plasmid extraction when it should be good quality. The manual also stated that this is suitable for mammlian tranfections, but i would think my cells won't be very happy if i try to put a bunch of RNA in it...

I am new to this field, so any suggestions will be deeply appreciated.

Floz

Hi everyone, I did a maxiprep and I want to use the sample for mammalian transfection. My 260 reading shows a concentration of 2.4ug/ul, I measured the 260/280 OD ratio and it is 1.91. If pure DNA is 1.8 and pure RNA is 2.0, does this mean that I have a too much RNA in my sample?

I looked into the manuals of some maxiprep kits and they say that you would expect a 260/280 ratio ~1.98!!! I have no idea why would you expect such a high ratio form a maxiprep plasmid extraction when it should be good quality. The manual also stated that this is suitable for mammlian tranfections, but i would think my cells won't be very happy if i try to put a bunch of RNA in it...

I am new to this field, so any suggestions will be deeply appreciated.

Floz

Hallo, I think your DNA is nice pure and you should not expect problems with transfection. Try to run the DNA on gel and you will see how much RNA is present in your maxipreps. You can use RNase to cleaved it and than proteinase K to remove RNase and ethanol precipitation to get your DNA
good luck