Compositions, methods, and kits for isolating nucleic acids using surfactants and proteases

The invention provides compositions and methods for releasing and for isolating nucleic acids from biological samples, preferably from whole tissue, using cationic surfactants and proteases. The surfactant-protease combinations, when used with whole tissue, macerate the tissue, lyse individual cells, release nucleic acids, and inactivate nucleases. Kits for isolating nucleic acids from biological samples, particularly from whole tissue, are also provided.