title: Host-guest chemistry in the gas phase: complex formation with 18-crown-6 enhances helicity of alanine-based peptides.
abstract: The gas-phase helix propensities of alanine-based polypeptides are studied with different locations of a Lys residue and host-guest interactions with 18-Crown-6 (18C6). A series of model peptides Ac-Ala(9-n)-LysH(+)-Ala(n) (n = 0, 1, 3, 5, 7, and 9) is examined alone and with 18C6 using traveling wave ion mobility mass spectrometry combined with molecular dynamics (MD) simulations. The gas-phase helices are observed from the peptides whose Lys residue is located close to the C-terminus so that the Lys exerts its capping effect on the C-terminal carbonyl groups. The peptides, which interact with 18C6 in the gas phase, show enhanced helical propensities. The enhanced helicity of the peptide in the complex is attributed by isolation of the Lys butylammonium group from the helix backbone and the interaction of methylene groups of 18C6, which possess localized positive partial charges, with C-terminal carbonyl groups serving as a cap to stabilize the helix.
authors: Department of Chemistry, Pohang University of Science and Technology, Republic of Korea.
authors: Jae Yoon
authors: JY
authors: Ko
authors: Sung Woo
authors: SW
authors: Heo
authors: Joon Ho
authors: JH
authors: Lee
authors: Han Bin
authors: HB
authors: Oh
authors: Hyungjun
authors: H
authors: Kim
authors: Hugh I
authors: HI
authors: Kim
mesh_terms: D000409:Alanine / Q000737:chemistry*; D003198:Computer Simulation; D043844:Crown Ethers / Q000737:chemistry*; D005740:Gases / Q000737:chemistry*; D008239:Lysine / Q000737:chemistry; D008956:Models, Chemical; D056004:Molecular Dynamics Simulation; D015394:Molecular Structure; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D018629:Spectrometry, Mass, Secondary Ion / Q000379:methods
chemical_list: D043844:Crown Ethers; D005740:Gases; D010455:Peptides; C015762:18-crown-6; D008239:Lysine; D000409:Alanine