Micelle-induced curvature in a water-insoluble HIV-1 Env peptide revealed by NMR dipolar coupling measurement in stretched polyacrylamide gel |
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Authors: | Chou James J Kaufman Joshua D Stahl Stephen J Wingfield Paul T Bax Ad |
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Institution: | Laboratory of Chemical Physics, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA. |
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Abstract: | The structure of a water-insoluble fragment encompassing residues 282-304 of the HIV envelope protein gp41 is studied when solubilized by dihexanoyl phosphatidylcholine (DHPC) and by small bicelles, consisting of a 4:1 molar ratio of DHPC and dimyristoyl phosphatidylcholine (DMPC). Weak alignment with the magnetic field was accomplished in a stretched polyacrylamide gel, permitting measurement of one-bond (1)H-(15)N, (13)Ca-(13)C', and (13)C'-(15)N dipolar couplings, which formed the basis for determining the peptide structure. In both detergent systems, the peptide adopts an alpha-helical conformation from residue 4 through 18. In the presence of the DHPC micelles the helix is strongly curved towards the hydrophobic surface, whereas in the presence of bicelles a much weaker curvature in the opposite direction is observed. |
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