L buffer with proteinase K and Sarkosyl

Amend the L buffer to a final concentration of 1% (w/v) Sarkosyl. Store L buffer with Sarkosyl at room temperature, and add proteinase K to 0.1 mg/ml just before use.

Some investigators substitute 0.5 M EDTA/1% (w/v) SDS/2 mg/ml proteinase K for the L buffer containing Sarkosyl and proteinase K. However, using high concentrations of proteinase K can become expensive and is unnecessary.