Ordered Aggregates of Fmoc-Diphenylalanine at Alkaline pH as a Precursor of Fibril Formation and Peptide Gelation.

The ultrashort peptide -fluorenylmethoxycarbonyl-phenylalanyl-phenylalanine (FmocFF) has been largely investigated due to its ability to self-assemble into fibrils (100 nm-μm scale) that can form a sample-spanning gel network. The initiation of the gelation process requires either a solvent switch (water added to dimethyl sulfoxide) or a pH-switch (alkaline to neutral) protocol, both of which ensure the solubility of the peptide as a necessary step preceding gelation. While the respective gel phases are well understood in structural and material characteristics terms the pregelation conditions are known to a lesser extent.

Tuning the thermostability of GHG gels by salts at different positions on the Hofmeister scale.

The influence of Hofmeister cations (NH, Na, Mg) and anions (HPO, CHCOO, Cl NO) on the thermostability of a GHG hydrogel was investigated. The combined results of UV circular dichroism (UVCD) and Small Amplitude Oscillatory Shear Rheology experiments reveal that the addition of salt reduces the stability of the gel phase and the underlying fibrils. In line with the cationic Hofmeister hierarchy, the chaotropic Mg ions caused the greatest thermal destabilization of the gel phase with the gel → sol transition temperature T value lowered by 10 °C.

Probing the versatility of cytochrome c by spectroscopic means: A Laudatio on resonance Raman spectroscopy.

Over the last 50 years resonance Raman spectroscopy has become an invaluable tool for the exploration of chromophores in biological macromolecules. Among them, heme proteins and metal complexes have attracted considerable attention. This interest results from the fact that resonance Raman spectroscopy probes the vibrational dynamics of these chromophores without direct interference from the surrounding.

Intrinsic Conformational Dynamics of Glycine and Alanine in Polarizable Molecular Dynamics Force Fields: Comparison to Spectroscopic Data.

Molecular dynamics (MD) is a great tool for elucidating conformational dynamics of proteins and peptides in water at the atomistic level that often surpasses the level of detail available experimentally. Structure predictions, however, are limited by the accuracy of the underlying MD force field. This limitation is particularly stark in the case of intrinsically disordered peptides and proteins, which are characterized by solvent-accessible and disordered peptide regions and domains.

Determining the nanostructure and main axis of gly-his-gly fibrils using the amide I' bands in FTIR, VCD, and Raman spectra.

The zwitterionic tripeptide glycyl-histidine-glycine (GHG) has been shown to self-assemble into visible crystalline fibrils that form a gel-supporting network with a very high storage modulus. Here we elaborate on the theory and experimental setup behind our novel approach employed to determining the main fibril axis for these gel-forming fibrils by simulating the amide I band profile for infrared absorption (IR), vibrational circular dichroism (VCD), and visible Raman scattering. We also highlight that combining these three vibrational spectroscopies can help in validating structures that are solved using powder x-ray diffraction analysis (PXRD).