Ethanol in my RNA/TE buffer
Dr. Hiranya S. Roychowdhury
hroychow at nmsu.edu
Thu Jun 24 16:15:55 EST 2004
Residual ethanol really doesn't stick around long. But, if you want to run a
sample of your nucleic acid on a gel, make sure the etoh is gone; for it makes
the sample float up due to "violent" mixing between the etoh and the aqueous
buffer. Additionally, some downstream reactions are sensitive to etoh.
However, it is a good idea not to let the RNA pellet dry up too much before the
addition of TE or water. Very dry RNA is very , very hard to resuspend in
aqueous solvents (don't ask me why, I don't know the answer to that). Same is
true for very large DNA, eg. genomic DNA preparations. So, the best way to
deal with the balance between etoh and drying is to add the aqueous buffer
immediately after the etoh is aspirated out and then to subject the resuspended
NA to a quick (1min) speedvac. In the absence of speedvac, leaving the tube in
a 37 C incubator for about 5min also does the trick.
Quoting Mark Ledesma <mledesma at uwm.edu>:
> I know it is customary when washing an RNA pellet with 75% ethanol to
> dry the ethanol off the pellet before suspending it in TE buffer.
> Could someone kindly explain why?
> Someone I know who looks kind of like me (it isn't me, really) just
> forgot to dry his pellet and surely has some ethanol in with his RNA
> and TE. How bad is this?
> Thanks for any help,
> Mark Ledesma
Hiranya S. Roychowdhury, Ph.D.
Coll. Asst. Professor,
Dept. of Chemistry & Biochemistry
Rm# 336, Chemistry Bldg.; MSC 3MLS
New Mexico State University
Las Cruces, NM 88003
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