As there has been strong evidence for a conformational and monomer-dimer equilibrium of the homodimeric structure 1 involving antiparallel oriented b 5.6 double and b 6.3 single helices (Fig. 2c , i-iii) (Küsel et al. 2007 ), a covalent linkage of both strands seemed to be mandatory in order to circumvent the described equilibria. This goal was fulfilled through the synthesis of the peptide hairpin 2 (Fig. 2c , iv) allowing for further studies that address peptide oligomerization within lipid model membrane complexes. The helix assembly is, thereby, driven by molecular recognition of the peptide nucleic acid (PNA) moieties at the membrane's exterior (Fig. 2c, v-vi; . The attachment of fluorescence probes and peptide nucleic acid (PNA) recognition moieties led to functional constructs, such as compound 3, that have already been tested for their dynamic dimerization within lipid bilayer structures via Förster resonance energy transfer (FRET) assays ). a b c Fig. 2 Molecular representation of the different D,L-alternating peptide types (a) ranging from the homodimeric species 1 to the designed hairpin 2 to the functionalized construct 3. Furthermore, the molecular structure of the homodimer 1 (b) (Küsel et al. 2007 ) as well as proposed equilibria (c) are sketched, either for homodimeric structures (i)-(iii) or the PNA-equipped transmembrane domains of 3 (v)-(vi) that undergo oligomerization driven by molecular recognition at the membrane's exterior Here, we probe the membrane reconstitution of the three presented kinds of b-helical species via GID and reciprocal space mapping (RSM) and evaluate their influence on the lateral lipid packing by addressing the lipid chain correlation peak. In the respective studies, parameters such as the sample composition, the relative humidity (RH), and the peptide-to-lipid (P/L) ratio are varied. The obtained results can be explained by a qualitative model that predominantly takes into account a hydrophobic mismatch situation as well as a lateral packing and ordering of the annular lipid shell that is correlated to the extent of peptide-lipid contact surface. Furthermore, we analyze the differentially (double) iodine-labeled hairpin species of type 2 via anomalous and in-house reflectivity elucidating their positioning with respect to the membrane normal (z axis) and confirming their transmembrane orientation. These experiments created the basis for a functional FRET assay that was reported elsewhere .