SMA Copolymer-lipid Nanodiscs
Membrane proteins vary in size and structure and play key roles in many important biological processes, including transportation, signal transduction, and multiple metabolic pathways. The biophysics, biochemistry, structural biology, and cell biology of membrane proteins are important parts of modern life science research. Nanodiscs are self-assembled discoidal particles consisting of phospholipids and amphiphilic helical band proteins called membrane scaffold proteins (MSP) and provide an enabling method for understanding the structure and function of membrane proteins.
Advantages
Nanodiscs are a new class of model membranes for the dissolution and study of integrated membrane proteins and membrane-associated proteins. Compared with other traditional membrane mimetic systems, nanodiscs have the following advantages.
- Nanodiscs provide a native-like, homogeneous membrane environment for handling membrane proteins.
- Proteins inside nanodiscs have better stability and better activity.
- Nanodiscs can control oligomerization of membrane proteins by changing the ratio of lipid, membrane protein, and MSP.
- Nanodiscs can precisely control the lipid compositions around the membrane protein.
- Nanodiscs allow simultaneous access to both faces of the membrane bilayer.
Product Range
Styrene maleic acid (SMA) copolymers
Styrene maleic acid (SMA) copolymers are broadly used for function and structure studies of membrane proteins. The significant advantages of using SMA copolymers include (1) generating a detergent-free system and (2) forming bilayer nanodiscs with phospholipids. Application of SMA copolymers opens an avenue of membrane protein extraction from cell membranes and proteoliposomes in the absence of detergent. The extracted membrane proteins are stabilized in the nanodiscs that mimic the bilayer structure of lipids in nature. The membrane proteins in nanodiscs can be purified and employed in biochemical, biophysical and biological experiments. For example, the nanodiscs can be used for structure studies of membrane proteins by electronic microscopy (EM). Typically, SMA copolymers 2:1 forms nanodiscs in a size about 30 nm while SMA copolymers 3:1 forms nanodiscs in a size about 10 nm. The ideal pH for nanodisc formation is between pH 7.0 – 8.0.
- SMA copolymer 2:1 for nanodiscs
- SMA copolymer 3:1 for nanodiscs
DOPC Nanodiscs
Nanodiscs of phospholipids may be used for scientific research involving membrane proteins or cell membranes. The DOPC nanodisc are prepared by solubilizing a liposome composed of DOPC: cholesterol: DSPE-PEG2000 (7.5: 1: 2.5) using SMA copolymers. The SMA to lipid mass ratio is 8:1. After the liposome solubilization, the SMA 3:1 copolymer yields nanodiscs in an average diameter about 10 nm. The SMA 2:1 copolymer yields nanodiscs in an average diameter about 30 nm. The total lipid concentration is 5 mg/ml and the SMA copolymer concentration is 40 mg/ml. The nanodiscs are formed in a buffer composed of 10 mM Tris-HCl, pH 7.6.
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