SDS (sodium dodecyl sulfate/sulphate) is an anionic detergent effective in both acidic and alkaline solutions. SDS has a wide variety of applications, but is most often used in protein and lipid solubilisation.
As a rule of thumb for the solubilisation/solubilization of proteins, SDS should be used at its critical micelle concentration (Womack'83 PMID 6882760). For the effects of SDS on protein conformation see Protein Structure by Creighton . For comparisons between SDS and other detergents for solubilisation of lipids, proteins, and its effect on enzymes activity see Womack '83 (PMID 6882760) and Creighton Protein Structure.