Looking for a generic inhibitor of amyloid-like fibril formation among flavone derivatives.

A range of diseases is associated with amyloid fibril formation. Despite different proteins being responsible for each disease, all of them share similar features including beta-sheet-rich secondary structure and fibril-like protein aggregates. A number of proteins can form amyloid-like fibrils in vitro, resembling structural features of disease-related amyloids.

Flavone derivatives as inhibitors of insulin amyloid-like fibril formation.

Several natural and synthetic flavone derivatives have been reported to inhibit formation of amyloid fibrils or to remodel existing fibrils. These studies suggest that the numbers and positions of hydroxyl groups on the flavone rings determine their effectiveness as amyloid inhibitors. In many studies the primary method for determining the effectiveness of inhibition is measuring Thioflavin T (ThT) fluorescence.

Estimating contribution of anthocyanin pigments to osmotic adjustment during winter leaf reddening.

The association between plant water stress and synthesis of red, anthocyanin pigments in leaves has led some plant biologists to propose an osmotic function of leaf reddening. According to this hypothesis, anthocyanins function as a solute in osmotic adjustment (OA), contributing to depression of osmotic potential (Ψ(π)) and maintenance of turgor pressure during drought-stressed conditions. Here we calculate the percent contribution of anthocyanin to leaf Ψ(π) during OA in two angiosperm evergreen species, Galax urceolata and Gaultheria procumbens.

Interactions of the osmolyte glycine betaine with molecular surfaces in water: thermodynamics, structural interpretation, and prediction of m-values.

Noncovalent self-assembly of biopolymers is driven by molecular interactions between functional groups on complementary biopolymer surfaces, replacing interactions with water. Since individually these interactions are comparable in strength to interactions with water, they have been difficult to quantify. Solutes (osmolytes, denaturants) exert often large effects on these self-assembly interactions, determined in sign and magnitude by how well the solute competes with water to interact with the relevant biopolymer surfaces.

Urea-amide preferential interactions in water: quantitative comparison of model compound data with biopolymer results using water accessible surface areas.

Two fundamentally different thermodynamic approaches are in use to interpret or predict the effects of urea on biopolymer processes: one is a synthesis of transfer free energies obtained from measurements of the effects of urea on the solubilities of small, model compounds; the other is an analysis of preferential interactions of urea with a range of folded and unfolded biopolymer surfaces. Here, we compare the predictions of these two approaches for the contribution of urea-amide (peptide) interactions to destabilization of folded proteins by urea. For these comparisons, we develop independent thermodynamic analyses of osmometric and solubility data characterizing interactions of a model compound with urea (or any other solute) and apply them to all five model compounds (glycine, alanine, diglycine, glycylalanine, and triglycine) where both isopiestic distillation (ID) and solubility data in aqueous urea solutions are available.

The exclusion of glycine betaine from anionic biopolymer surface: why glycine betaine is an effective osmoprotectant but also a compatible solute.

Paradoxically, glycine betaine (N,N,N-trimethyl glycine; GB) in vivo is both an effective osmoprotectant (efficient at increasing cytoplasmic osmolality and growth rate) and a compatible solute (without deleterious effects on biopolymer function, including stability and activity). For GB to be an effective osmoprotectant but not greatly affect biopolymer stability, we predict that it must interact very differently with folded protein surface than with that exposed in unfolding. To test this hypothesis, we quantify the preferential interaction of GB with the relatively uncharged surface exposed in unfolding the marginally stable lacI helix-turn-helix (HTH) DNA binding domain using circular dichroism and with the more highly charged surfaces of folded hen egg white lysozyme (HEWL) and bovine serum albumin (BSA) using all-gravimetric vapor pressure osmometry (VPO) and compare these results with results of VPO studies (Hong et al.