Membrane Protein Crystallization
2003; Elsevier BV; Linguagem: Inglês
10.1016/b978-012361776-7/50008-5
Autores Tópico(s)Lipid Membrane Structure and Behavior
ResumoMembrane proteins are the target for a majority of drugs, and structures can be used for rational design and development of the compounds. The most widely used method for determination of protein structures at high, near atomic resolution is x-ray crystallography that requires well-ordered 3D crystals grown from protein solution. 3D crystallization of membrane proteins for high-resolution structural studies is challenging due to the amphipathic surface of the molecules. Embedded in the membrane bilayer, the contact sites of the protein with the acyl chains of the phospholipids are hydrophobic, whereas the polar surfaces are exposed to the polar head groups of the lipids and to the aqueous phases. Membrane proteins can be crystallized within a phospholipid bilayer, resulting in two-dimensional crystals, which are used for structure determination by electron microscopy. Membrane proteins can be solubilized from the lipid bilayer in their native conformation by the use of detergents. The amphipathic surface of membrane proteins allows for two ways to form 3D crystals, a necessity for x-ray crystallographic analysis. Membrane protein crystallization is based on empirical screening steps and is still far from routine. Important factors for the successful crystallization of a membrane protein are stability and homogeneity of the protein and the choice of the detergent. Removing bottlenecks, especially in overproduction of proteins from eukaryotic organisms and in stabilization of proteins, is still needed so that structure determination of membrane proteins will be an approachable aim to study the mechanism of membrane proteins.
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