Molecule of the Day

It’s remarkable how different RNA and DNA are, considering they’re just one atom different. RNA is much more prone to fall apart; you can put DNA in basic solution without any problem, but RNA will begin to hydrolyze. Life takes advantage of the ease with which RNA is degraded. It has a much more ephemeral role in the cell; your genome is encoded long-term via DNA, and RNA is typically generated only as needed en route to proteins.

Because of this, RNA is degraded quickly when it’s not around for a good reason. This is accomplished by the ubiquitous, aptly named RNAses. They’re all over your hands right now. If you’re a molecular biologist and you’d like to play around with RNA, you’ve got to be careful of RNAses. One reagent used to deactivate them is DEPC – diethylpyrocarbonate.


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It’s the ethyl diester of pyrocarbonic acid. Pyro- is a somewhat archaic prefix for the anhydride of an acid; pyrolysis (heating) of some acids causes loss of water and formation of the anhydride. This meaning is also seen in pyrophosphate.

Acid anhydrides are reactive species, much like acid chlorides. RNAses are modified and deactivated by DEPC. After you’re done, you autoclave your DEPC-containing mixture. Any unreacted DEPC should convert to ethanol and carbonic acid, which goes to carbon dioxide. These are pretty benign, but it’s vital to inactivate leftover DEPC with thorough autoclaving – DEPC will happily screw up other components of your reaction if it’s still hanging around..