Complete removal of DNA

Complete removal of DNA

Figure 1: Addition of salt leads to DNA dissociation from proteins, making it available for degradation by the highly active SAN.

The amount of SAN and time needed for complete removal of DNA will depend on the extract.

A typical cell lysate contains DNA, RNA, nucleotide-binding proteins, lipids, detergents etc. and is more complex than an optimal DNA-containing reaction buffer. Thus, for complete removal of DNA in a bacterial lysate more SAN is commonly needed than for buffered solutions.

To enhance dissociation of DNA from proteins, making DNA available for degradation, adjust the concentration of NaCl to 0.5 M and incubate at 4°C overnight. Then add SAN and incubate at 25°C for 30 minutes. The amount of SAN needed will depend on the extract composition as well as incubation time and temperature, but is commonly between 50-1000 U/ml. The removal of DNA from the extract should be verified using agarose gel electrophoresis.

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