Biological membranes consist of phospholipids that are similar to detergents as they have the same amphipathic properties. The phospholipids have a charged polar head normally connected to two hydrophobic groups or tails. The phospholipids assemble as bilayers, with the hydrophobic tails between two faces of polar head groups.
The proteins are released from lipid bilayers by detergents as the detergent micelles have similar properties as the lipid bilayer. The integral membrane proteins embed themselves in the detergent micelles protecting their hydrophobic domains from aggregation.
A schematic of how detergents solubilize membrane proteins is shown below. At low detergent concentrations, less than the detergent’s CMC, the detergent molecules insert themselves in the lipid membrane and begin partioning the lipid bilayer. At concentrations equal to, or higher than the detergent’s CMC, the lipid bilayer becomes saturated with detergent molecules and the lipid bilayer breaks apart. The resulting products are protein-detergent complexes, where the detergent hydrophobic regions bind to the protein hydrophobic domains protecting them from aggregations. In addition to these, detergent and detergent-lipid micelles are formed.
The manufacturing of commercial detergents, including non-ionic detergents, results in the presence of sulfhydryl oxidizing agents, peroxides, salts and carbonyl compounds. The level of these harmful reagents, particularily the peroxides and carbonyls (aldehydes) can increase over time as the product degrades.
The graph below shows a comparison between the aldehyde and peroxidelevels in G-Biosciences Proteomic Grade Detergents and commercial non proteomic grade detergents.
The oxidizing agents, peroxides and aldehydyes will react with protein amino acids causing changes to its primary structure, molecular mass and may also inhibit protein:protein interactions.
