Diethylpyrocarbonate

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Diethylpyrocarbonate (DEPC) is used in the laboratory to inactivate the RNAse enzymes from water and other laboratory utensils. It inactivates the RNases by the covalent modifications of the histidine residues. DEPC cannot be used with Tris buffer since it inactivates DEPC by reacting with it. Enzymes or chemicals which have actine -O:, -N: or -S: cannot be treated with DEPC to become RNase-free as DEPC reacts with these species.

Water is usually treated with 0.1% v/v diethylpyrocarbonate for at least 1 hour at 37°C and then autoclaved (at least 15 min) to inactivate traces of DEPC. Inactivation of DEPC on this manner yields CO₂ and H₂O.

DEPC treated (and therefore RNAse-free) water is used in all handling of RNA in the laboratory, to reduce the risk of RNA being degraded by RNAses.

DEPC derivatization of histidines is also used to study the importance of histidyl residues in enzymes. Modification of histidine by DEPC results in carbethoxylate derivates at the N-omega-2 nitrogen of the imidazole ring. DEPC modification of histidines can be reversed by treatment with 0.5M hydroxylamine at neutral pH.