Creative Biolabs now provides high-quality, professional services in membrane protein solubilization/stabilization to facilitate our customers' research development and applications of membrane proteins.
Unlike water-soluble proteins, most membrane proteins cannot be solubilized or stabilized in aqueous solutions without the aid of any amphipathic materials. One of the most common difficulties in handling membrane proteins is the choice of the amphipathic materials. Amphipathic materials can play an indispensable role in the extraction, solubilization, stabilization, characterization, functionalization, and activation of membrane proteins. The most commonly used amphipathic materials for solubilizing and stabilizing membrane proteins include detergents, lipids, and amphipols.
Detergents or short-chain lipids aggregate to form micelles above their critical micelle concentrations (CMCs) in aqueous solutions. Long-chain lipids can also be used together with detergents to form bi-component micelles.
Bilayer-forming lipids alone can form spherical liposomes in aqueous solutions. They are also one of the main components of bicelles and nanodiscs, whose edges are wrapped and stabilized in aqueous solutions by detergents or short-chain lipids and membrane scaffold proteins or styrene-maleic acid copolymers, respectively.
Nanodiscs are a bunch of membrane protein-lipid complex that held together by a belt-like membrane scaffold protein (MSP). Comparing to micelles, bicelles or proteoliposomes, nanodisc format can offer a more compact, native-like environment. Therefore, they are highly stable, controllable and monodisperse, which is very suitable for many kinetics and functional studies.
Amphipols are polymers produced by chemically linking octylamine and/or isopropylamine to a portion of the carboxylic groups of low-molecular-weight polyacrylic acids via the formation of amide bonds. They can solubilize membrane proteins by wrapping them on their hydrophobic surface in aqueous solutions.
SMA is a low molecular weight amphipathic polymer and a hydrolyzed form of the styrene-maleic anhydride (SMAnh) copolymer. SMA can directly extract membrane proteins from bacteria, yeast, insect and mammalian cell membranes without the help of detergent. Therefore, it is relatively easy to prepare and can preserve the native structure of target membrane protein.
In all cases, the hydrophilic head groups of the amphipathic solubilizing materials form the surface in contact with solvent molecules while their hydrophobic tails or side chains are sequestered inwards to stabilize incorporated membrane proteins. Once dissolved using proper solubilization materials, membrane proteins can be handled easily in many kinds of purifications, characterizations, and applications including but not limited to:
The proper solubilizing materials may differ for different membrane proteins, different characterization or application purposes. Use of improper or insufficient surfactants may result in the unfolding, conformational change, loss of function or activity and/or unwanted aggregation of membrane proteins, which may greatly impede the research, development, and application of membrane proteins. However, this has seldom been a problem for Creative Biolabs. Equipped with the powerful micelle, bicelle, liposome, nanodisc, and amphipol screening platforms, we can easily find the most suitable condition for solubilizing and stabilizing each membrane protein. At Creative Biolabs, more than 100 detergents and lipids are available for screening using our detergent screening platform and lipid screening platform. We will evaluate the folding, stability, oligomeric state and monodispersity of solubilized membrane proteins for each screened amphipathic material based on the A320/A280 ratio, HPSEC profile, ultracentrifugation result, and/or other measurements.
Scientists at Creative Biolabs have decades of experience and abundant knowledge in membrane protein solubilization and stabilization and are always willing to work closely with our customers. We believe we can contribute to our clients’ membrane protein projects with our high-quality service and best efforts. Please feel free to inquire us for more information.