Methods for monitoring protein-membrane binding. Comparison based on the interactions between amyloidogenic protein human cystatin C and phospholipid liposomes.

A cell membrane is an essential cellular component providing protection against the outer environment. It is also a host for proteins and carbohydrates responsible for, e.g. transporter, receptor, or enzymatic functions. In parallel, the membrane may also be implicated in pathological processes leading, e.g. to the oligomerization of amyloid-forming proteins, a hallmark of i.a. Alzheimer's disease. The increasing need for detailed information on mechanisms driving the amyloid formation and the potential role of cell membranes in the process proves the research on protein-membrane interactions biologically relevant. Considering the potential and limitations of the relatively well established and newly developed methods, this study focused on selecting methods that allow a broad and comprehensive description of interactions between amyloidogenic protein human cystatin C and lipid bilayers. In the first step, dot-blot and ELISA tests were selected as techniques allowing fast screening for protein-ligand interactions. Next, surface plasmon resonance, spectral shift, biolayer interferometry, and switchSENSE® technology were used to determine kinetic parameters and binding constants for interactions between human cystatin C and the selected lipid bilayers. Based on the obtained results we have proposed the most promising candidates for monitoring of interactions and determining affinity between amyloidogenic proteins and membrane mimetics.

Phosphorylated resveratrol as a protein aggregation suppressor in vitro and in vivo.

The stability of proteins in solution poses a great challenge for both technical applications and molecular biology, including neurodegenerative diseases. In this work, a phosphorylated resveratrol material was examined for its anti-aggregation properties in vitro and in vivo. Here, an anti-fibrillation effect could be measured for amyloid beta and human insulin in vitro and general anti-aggregation properties for crude chicken egg white in solution. Using a drosophila fly model for the overexpression of amyloid beta protein, changes in physiological protein aggregation and improved locomotor abilities could be observed in the presence of dietary phosphorylated resveratrol.

Carl Neuberg's hydrotropic appearances (1916).

In his 1916 land-mark paper "Hydrotropic appearances", Carl Neuberg coined the term "hydrotropy", referring to the solubilisation effect of hydrophobic molecules by small, amphiphilic compounds. In this voluminous work he examines 43 different compounds for their hydrotropic effect and touches on many aspects that later became relevant to hydrotrope science (e.g. applications in pharma, green chemistry, pre-ouzo effect, etc.). Given the significance of his work, it is still widely cited today. However, poor availability and a potential language barrier will severely limit the accessibility for international researchers. Therefore, this translation into the English language seeks to provide access to both, his original thoughts as well as his prolific experimental work on this topic.

Salting-in and salting-out effects of short amphiphilic molecules: a balance between specific ion effects and hydrophobicity.

Amphiphilic molecules (e.g. hydrotropes) that enhance the solubility of hydrophobic compounds in water are often charged. As a result, such compounds also show specific ion effects. These effects can either strengthen or weaken the solubilisation power of amphiphilic molecules, depending on their degree of ion hydration. They can even prevail and transform an apparent solubilizer into an "anti-hydrotrope", i.e. a salting-out agent. In the present paper, we discuss this subtle balance between specific (Hofmeister) effects exerted by ionic headgroups and the hydrophobicity of the residual compound structure, including the size of the molecule and the presence of electron-withdrawing groups.