Premium
Conformation and orientation of penetratin in phospholipid membranes
Author(s) -
Clayton A. H. A.,
Atcliffe B. W.,
Howlett G. J.,
Sawyer W. H.
Publication year - 2006
Publication title -
journal of peptide science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 66
eISSN - 1099-1387
pISSN - 1075-2617
DOI - 10.1002/psc.715
Subject(s) - circular dichroism , chemistry , phospholipid , vesicle , phosphatidylcholine , peptide , membrane , phosphatidylserine , micelle , crystallography , biophysics , aqueous solution , biochemistry , organic chemistry , biology
The binding, conformation and orientation of a hydrophilic vector peptide penetratin in lipid membranes and its state of self‐association in solution were examined using circular dichroism (CD), analytical ultracentrifugation and fluorescence spectroscopy. In aqueous solution, penetratin exhibited a low helicity and sedimented as a monomer in the concentration range ∼50–500 µ M . The partitioning of penetratin into phospholipid vesicles was determined using tryptophan fluorescence anisotropy titrations. The apparent penetratin affinity for 20% phosphatidylserine/80% egg phosphatidylcholine vesicles was inversely related to the total peptide concentration implying repulsive peptide–peptide interactions on the lipid surface. The circular dichroism spectra of the peptide when bound to unaligned 20% phosphatidylserine/80% egg phosphatidylcholine vesicles and aligned hydrated phospholipid multilayers were attributed to the presence of both α‐helical and β‐turn structures. The orientation of the secondary structural elements was determined using oriented circular dichroism spectroscopy. From the known circular dichroism tensor components of the α‐helix, it can be concluded that the orientation of the helical structures is predominantly perpendicular to the membrane surface, while that of the β‐type carbonyls is parallel to the membrane surface. On the basis of our observations, we propose a novel model for penetratin translocation. Copyright © 2005 European Peptide Society and John Wiley & Sons, Ltd.