X-ray scattering studies of maquette peptide monolayers. 2. Interferometry at the vapor/solid interface

We apply X-ray interferometry to study the profile structure of Langmuir-Blodgett (LB) monolayers containing maquette peptides, de novo di-alpha -helical synthetic peptides designed as model systems for studying biological electron transfer. The results demonstrate that it is possible to create monolayers with the peptide vectorially oriented with its helical ards (the direction of electron transfer within the holopeptide) approximately normal to the surface of the solid support. This orientation can even be achieved when the orientation of the peptide in the precursor Langmuir film at the air/water interface is parallel to the surface, indicating that reorganization of the monolayer can occur during or after LB deposition. Though issues regarding the low density of the film and variability between samples remain to be addressed, the work represents an important step toward future correlated functional/structural studies of these peptides.