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An amphipathic polypeptide derived from poly‐γ‐glutamic acid for the stabilization of membrane proteins
Author(s) -
Han SeongGu,
Na JungHyun,
Lee WonKyu,
Park Dongkook,
Oh Jihye,
Yoon SungHo,
Lee ChengKang,
Sung MoonHee,
Shin YeonKyun,
Yu Yeon Gyu
Publication year - 2014
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.2575
Subject(s) - amphiphile , chemistry , bacteriorhodopsin , liposome , sodium dodecyl sulfate , transmembrane protein , membrane protein , membrane , micelle , biochemistry , biophysics , polymer , receptor , organic chemistry , biology , aqueous solution , copolymer
Difficulties in the extraction of membrane proteins from cell membrane and their solubilization in native conformations have hindered their structural and biochemical analysis. To overcome these difficulties, an amphipathic polypeptide was synthesized by the conjugation of octyl and glucosyl groups to the carboxyl groups of poly‐γ‐glutamic acid (PGA). This polymer, called amphipathic PGA (APG), self‐assembles as mono‐disperse oligomers consisted of 4–5 monomers. APG shows significantly low value of critical micelle concentration and stabilization activity toward membrane proteins. Most of the sodium dodecyl sulfate (SDS)‐solubilized membrane proteins from Escherichia coli remain soluble state in the presence of APG even after the removal of SDS. In addition, APG stabilizes purified 7 transmembrane proteins such as bacteriorhodopsin and human endothelin receptor Type A (ET A ) in their active conformations. Furthermore, ET A in complex with APG is readily inserted into liposomes without disrupting the integrity of liposomes. These properties of APG can be applied to overcome the difficulties in the stabilization and reconstitution of membrane proteins.