103b] The use of sodium and lithium dodecyl sulfate in nucleic acid isolation

Abstract

Dodecyl sulfate (lauryl sulfate) used either as the sodium salt—sodium dodecyl sulfate (SDS)—or the more soluble lithium salt (LDS) is a powerful detergent that has found wide application in the analytical biochemistry of nucleic acids because of its ability to release nucleic acids from their associations with protein or lipoprotein structures in which they normally occur inside the cell. Recently, the amide derivative sodium dodecyl sarcosinate has been introduced because of its solubility in high concentrations of cesium chloride. The precise mechanism of action of these detergents is not known, but it is likely that the hydrocarbon chain of SDS competes for hydrophobic bonds. This tendency in combination with the strongly hydrophilic sulfate group presumably causes the formation of water-soluble complexes or micelles. Two additional properties make dodecyl sulfate particularly suitable for use in nucleic acid isolation;the anionic detergent appears to be an inhibitor of nucleases and its negative charge prevents it from interacting with nucleic acids. SDS has often been used in combination with phenol for the preparative isolation of nucleic acids free of protein. This chapter confines to the examples of the use of dodecyl sulfate alone and illustrates the great potential of the method in the cases where optimal analytical resolution is of paramount importance. The chapter presents detailed directions for the release and characterization of nucleic acids from a number of representative sources such as (1) viral RNA, (2) bacterial DNA, (3) ribosomal RNA (rRNA), (4) messenger RNA (mRNA), (5) and transfer RNA.