Detergents

Some detergents can be used to solubilize recombinant proteins, while others are recommended for the stabilization, crystallization, or denaturation of proteins. Detergents can align at aqueous/non- aqueous interfaces, resulting in reduced surface tension, increased miscibility, and stabilization of emulsions. For all TRIC experiments the addition of non- ionic detergents such as Tween®20 (0.005 %), or Pluronic®F- 127 (0.1%) is strongly recommended to prevent sample Aggregation and Adsorption to labware. It is not recommended to mix different types of detergent.

• Anionic and cationic detergents are considered biologically “harsh” detergents because they modify protein structure to a greater extent than neutrally charged detergents. Examples are SDS, deoxycholate and CHAPS.
• Non-ionic detergents are considered to be “mild” detergents because they are less likely than ionic detergents to denature proteins. By not separating protein-protein bonds, non-ionic detergents allow the protein to retain its native structure and func- tionality, although detergents with shorter hydrophobic chain lengths are more likely to cause protein deactivation. Examples for suitable detergents are Tween® 20, Tween® 80, Pluronic® F-127, Triton® X-100 and DDM.
• Non-detergent sulfobetaines (NDSB), although not detergents, possess hydrophilic groups similar to those of zwitterionic detergents but with shorter hydrophobic chains. Sulfobetaines do not form micelles. They have been reported to improve the yield of Membrane Proteins when used with detergents and to prevent aggregation of denatured proteins.
• As an alternative to a detergent the addition of 0.1% of PEG 8000 to an assay buffer can also help to stabilize protein molecules and avoid surface adsorption.