The 21‐residue surfactant peptide (LysLeu4)4Lys(KL4) is a transmembrane α‐helix with a mixed nonpolar/polar surface

FEBS Letters

Curstedt, Tore³  Johansson, Jan¹  Ruysschaert, Jean-Marie²  Vandenbussche, Guy²  Gustafsson, Magnus¹ 

[1] Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-17177 Stockholm, Sweden;Laboratoire de Chimie-Physique des Macromolécules aux Interfaces, Université Libre de Bruxelles, B-1050 Brussels, Belgium;Department of Clinical Chemistry, Karolinska Institutet at Danderyd Hospital, S-18288 Danderyd, Sweden

关键词: Pulmonary surfactant;    SP-B;    SP-C;    Synthetic peptide;    Lipid-associated peptides;    Secondary structure;    Transmembrane α-helix;    Membrane protein;    ATR;    attenuated total reflection;    CD;    circular dichroism;    DPC;    dodecylphosphocholine;    DPPC;    1;    2-dipalmitoyl-sn-glycero-3-phosphocholine;    FTIR;    Fourier transform infrared;    PG;    phosphatidylglycerol;    TFA;    trifluoroacetic acid;   

DOI  :  10.1016/0014-5793(96)00290-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The 21-residue peptide KLLLLKLLLLKLLLLKLLLLK (KL₄) has been synthesized and analyzed regarding its secondary structure and orientation in lipid environments. Fourier transform infrared and circular dichroism spectroscopy shows that the peptide exhibits approximately 80% α-helical content both in dodecylphosphocholine micelles and in 1,2-dipalmitoyl-glycero-3-phosphocholine (DPPC)/phosphatidylglycerol (PG) 7:3 (w/w) bilayers. The positively charged lysine residues are evenly distributed over the entire, otherwise nonpolar, circumference of the helix. This is in sharp contrast to the uneven distribution of polar and nonpolar residues in amphipathic helices. Fourier transform infrared spectroscopy of the peptide inserted in DPPC/PG bilayers shows that the helical axis is oriented parallel to the lipid acyl chains. These data do not support a previous hypothesis that the KL₄ peptide interacts with peripheral parts of a phospholipid monolayer and mimics the pulmonary surfactant protein SP-B, which is composed of several amphipathic α-helices. KL₄ accelerates the spreading of phospholipid mixtures at an air/water interface but does so less efficiently than other transmembranous helical polypeptides studied.

【 授权许可】

Unknown