Specular neutron reflectivity and the structure of
artificial protein maquettes vectorially oriented at interfaces
Strzalka J, Gibney BR, Satija S, Blasie JK
PHYSICAL REVIEW E
70 (6): Art. No. 061905 Part 1, 9 DEC 2004
Artificial peptides can be designed to possess a variety of functionalities.
If these peptides can be ordered in an ensemble, the functionality can impart
macroscopic material properties to the ensemble. Neutron reflectivity is
shown to be an effective probe of the intramolecular structures of such peptides
vectorially oriented at an interface, key to ensuring that the designed molecular
structures translate into the desired material properties of the interface.
A model-independent method is utilized to analyze the neutron reflectivity
from an alkylated, di-alpha-helical peptide, containing perdeuterated leucine
residues at one or two pre-selected positions, in mixed Langmuir monolayers
with a phospholipid. The results presented here are more definitive than
prior work employing x-ray reflectivity. They show explicitly that the di-helical
peptide retains its designed alpha-helical secondary structure at the interface,
when oriented perpendicular to the interface at high surface pressure, with
the helices projecting into the aqueous subphase without penetrating the
layer of phospholipid headgroups.