2 research outputs found
Softness of Atherogenic Lipoproteins: A Comparison of Very Low Density Lipoprotein (VLDL) and Low Density Lipoprotein (LDL) Using Elastic Incoherent Neutron Scattering (EINS)
Apolipoprotein B100 (apoB100)-containing plasma lipoproteins (LDL and VLDL) supply tissues and cells with cholesterol and fat. During lipolytic conversion from VLDL to LDL the size and chemical composition of the particles change, but the apoB100 molecule remains bound to the lipids and regulates the receptor mediated uptake. The molecular physical parameters which control lipoprotein remodeling and enable particle stabilization by apoB100 are largely unknown. Here, we have compared the molecular dynamics and elasticities of VLDL and LDL derived by elastic neutron scattering temperature scans. We have determined thermal motions, dynamical transitions, and molecular fluctuations, which reflect the temperature-dependent motional coupling between lipid and protein. Our results revealed that lipoprotein particles are extremely soft and flexible. We found substantial differences in the molecular resiliences of lipoproteins, especially at higher temperatures. These discrepancies not only can be explained in terms of lipid composition and mobility but also suggest that apoB100 displays different dynamics dependent on the lipoprotein it is bound to. Hence, we suppose that the inherent conformational flexibility of apoB100 permits particle stabilization upon lipid exchange, whereas the dynamic coupling between protein and lipids might be a key determinant for lipoprotein conversion and atherogenicity
Peptides at the Interface: Self-Assembly of Amphiphilic Designer Peptides and Their Membrane Interaction Propensity
Self-assembling
amphiphilic designer peptides have been successfully
applied as nanomaterials in biomedical applications. Understanding
molecular interactions at the peptide–membrane interface is
crucial, since interactions at this site often determine (in)Âcompatibility.
The present study aims to elucidate how model membrane systems of
different complexity (in particular single-component phospholipid
bilayers and lipoproteins) respond to the presence of amphiphilic
designer peptides. We focused on two short anionic peptides, V<sub>4</sub>WD<sub>2</sub> and A<sub>6</sub>YD, which are structurally
similar but showed a different self-assembly behavior. A<sub>6</sub>YD self-assembled into high aspect ratio nanofibers at low peptide
concentrations, as evidenced by synchrotron small-angle X-ray scattering
and electron microscopy. These supramolecular assemblies coexisted
with membranes without remarkable interference. In contrast, V<sub>4</sub>WD<sub>2</sub> formed only loosely associated assemblies over
a large concentration regime, and the peptide promoted concentration-dependent
disorder on the membrane arrangement. Perturbation effects were observed
on both membrane systems although most likely induced by different
modes of action. These results suggest that membrane activity critically
depends on the peptide’s inherent ability to form highly cohesive
supramolecular structures