SDS goes by the name sodium dodecyl sulfate (SDS) or sodium lauryl sulfate (SLS). In its purified state SDS is a white powder of medium molecular weight (M.W. or F.W. of 288.38, C12H25O4SNa. A modified form of SDS and SLS is sodium laureth sulfate (M.W. or F.W. 418.53, C12+2nH25+4nNaO4+nS). Each of these simple compounds has importance for a number of scientific and household roles.
Various modifications of the SDS compound are ammonium dodecyl sulfate with the ammonium group substituted for sodium and the previously-mentioned laureth form of sodium dodecyl sulfate as used in some detergents and antibacterial hand soaps.
SDS or Sodium Dodecyl Sulfate – Use in Protein Chemistry
SDS is used during protein purification and for studying protein molecular weights by polyacrylamide electrophoresis (PAGE). Proteins are dissolved in a solution of SDS which is an anionic detergent that binds one SDS molecule to every two amino acid residues in the entire protein molecule. SDS is a detergent that promotes a linear (straightened, non-globular) configuration of the native proteins. Any cross-linking disulfide covalent bonds in the protein are broken by the use of mercaptoethanol (2-thioethanol) or dithiothreitol. These chemical treatments permit different types of protein to be characterized and defined according their specific molecular weight (MW). The charge of each protein is proportional to the mass of the protein in the SDS solution and each protein will migrate accordingly in the PAGE. Upon completion of the electrophoresis the proteins in the gel are treated with silver or a dye such as Coomassie blue to stain and reveal the proteins. The positions of the proteins on the gel are compared to known molecular weight standards and by this means the true molecular weights can be determined.
The PAGE profiles pictured in this SDS article are clear representations of different proteins with defined weight characteristics. PAGE profiles are a simple and direct way to define, characterize, study, evaluate and understand important proteins that are produced by genes. A simple gene mutation can lead to a subtle protein changes that may be detected by molecular weight changes in the PAGE.
Sodium Dodecyl (Lauryl) & Laureth Sulfates– Detergent and Foam Agent in Household Products
Dodecyl (lauryl) and laureth sulfates have important detergent and foaming characteristics that make them useful for toothpastes, liquid hand soaps and liquid detergents. And what is a detergent? A detergent is any chemical that has the ability to capture and remove or separate or cause to go into suspension or solution various compounds, dirt, debris and organic substances. So, toothpastes commonly contain SDS (SLS) as one of the components that helps to separate, free and remove food and debris in and around the teeth and gums. This detergent action permits this debris to be expelled from the mouth to prevent tooth decay and pyorrhea of the gums. Likewise, hand washing liquid soaps often use SDS detergent and some liquid laundry detergents employ SDS (SLS) to remove dirt and debris from clothing to freshen it and make it whole.
Sources
Berg, J. M. et al. "The Purification of Proteins Is an Essential First Step in Understanding Their Function." Accessed 8 September, 2011 @ ncbi.nlm.nih.gov/books/NBK22410/
Human Health Services U.S. "Household Products Database." Accessed 8 September, 2011 @ householdproducts.nlm.nih.gov
Oxford Chemistry Lectures. "Sodium Laureth Sulfate." Accessed 8 September, 2011 @ chem.ox.ac.uk/it_lectures/chemistry/course/ityeartwo/html2/elvive.htm
Donald Reinhardt - Think, read, write & live well always. DJR has a PhD in Biology/Microbiology & is a Fellow & Diplomate, ASM Amer Acad Micro.
Join the Conversation