Superoxide Dismutase 1 Folding Stability as a Target for Molecular Tweezers in SOD1-Related Amyotrophic Lateral Sclerosis.

Protein misfolding and aggregation are hallmarks of many severe neurodegenerative diseases including Alzheimer's, Parkinson's and Huntington's disease. As a supramolecular ligand that binds to lysine and arginine residues, the molecular tweezer CLR01 was found to modify the aggregation pathway of disease-relevant proteins in vitro and in vivo with beneficial effects on toxicity. However, the molecular mechanisms of how tweezers exert these effects remain mainly unknown, hampering further drug development.

Sequestration of Proteins in Stress Granules Relies on the In-Cell but Not the Folding Stability.

Stress granules (SGs) are among the most studied membraneless organelles that form upon heat stress (HS) to sequester unfolded, misfolded, or aggregated protein, supporting protein quality control (PQC) clearance. The folding states that are primarily associated with SGs, as well as the function of the phase separated environment in adjusting the energy landscapes, remain unknown. Here, we investigate the association of superoxide dismutase 1 (SOD1) proteins with different folding stabilities and aggregation propensities with condensates in cells, and by simulation.

Alteration of water absorption in the THz region traces the onset of fibrillation in proteins.

Using terahertz spectroscopy, we established the alteration of the collective hydration of water during the fibrillation process (native → intermediate → fibril) of a model protein bovine serum albumin. This label-free study concludes that water dynamics change systematically with protein conformational changes as it experiences a hydrophobic environment during the initial protein unfolding process, followed by the release of bound water during oligomerization and finally the hydrophobic interior of the fibril.

Thermal stability modulation of the native and chemically-unfolded state of bovine serum albumin by amino acids.

Cells are crowded with various cosolutes including salts, osmolytes, nucleic acids, peptides and proteins. These cosolutes modulate the protein folding equilibrium in different ways, however, a unifying concept remains elusive. To elucidate the cosolute size-effect, macromolecular crowders are commonly compared to their monomeric building blocks (e.

Polyethylene glycols affect electron transfer rate in phenosafranin-DNA complex.

Long distance electron transfer (ET) between small ligands and DNA is a much studied phenomenon and is principally believed to occur through electron (or hole) hopping. Several studies have been carried out in aqueous environments while in real biological milieu the DNA molecules experience a more dense and heterogeneous environment containing otherwise indifferent molecular crowders. It is therefore expected that the ET could get modified in the presence of crowding agent and to investigate that we have made elaborate studies on steady state and time-resolved (picosecond (ps) and femtosecond (fs)-resolved) emission properties of a phenosafranine (PSF) intercalated to calf thymus (CT) DNA in the presence of ethylene glycol (EG) and polyethylene glycols (PEG) of different chain lengths (PEG 200, 400 and 1000).

Two Photon Spectroscopy Can Serve as a Marker of Protein Denaturation Pathway.

Rhodamine group of molecules are widely used dyes for imaging of biological molecules. Application of these dyes however includes a limitation that these molecules absorb in the visible range of the spectrum, which does not fall in the 'biologically transparent window' (BTW). Two photon absorption (TPA) process could come up with an alternate solution to this as these dyes could be excited in the near infrared (NIR) window to extract similar information.

Soft interaction and excluded volume effect compete as polyethylene glycols modulate enzyme activity.

Polyethylene glycols (PEGs) can either preferentially bind to biomolecules or exert excluded volume effect depending upon their chain length and concentration. We have studied the effect of ethylene glycol (EG) and PEGs of different chain lengths (M 400 and 4000) on the enzyme efficiency of hen-egg-white lysozyme (HEWL) on Micrococcus lysodeikticus (M. Lys.

Effect of Phospholipid Headgroup Charge on the Structure and Dynamics of Water at the Membrane Interface: A Terahertz Spectroscopic Study.

Biological membranes are highly organized supramolecular assemblies of lipids and proteins. The membrane interface separates the outer (bulk) aqueous phase from the hydrophobic membrane interior. In this work, we have explored the microstructure and collective dynamics of the membrane interfacial hydration shell in zwitterionic and negatively charged phospholipid membrane bilayers using terahertz time-domain spectroscopy.

Decisive Role of Hydrophobicity on the Effect of Alkylammonium Chlorides on Protein Stability: A Terahertz Spectroscopic Finding.

Many biologically important processes involve a subtle interplay between Columbic and hydrophobic interactions among molecular groups with water. A comprehensive understanding of such processes, specially while occurring simultaneously in the same molecule is of practical importance. In this contribution, we report the ultrafast (subpicosecond to picosecond) collective hydrogen bond dynamics of water in the extended hydration layers in a series of alkylammonium chloride salts using THz time domain spectroscopic (TTDS) technique (0.

Collective hydration dynamics in some amino acid solutions: A combined GHz-THz spectroscopic study.

A detailed understanding of hydration of amino acids, the building units of protein, is a key step to realize the overall solvation processes in proteins. In the present contribution, we have made a combined GHz (0.2-50) to THz (0.

Enhanced Catalytic Activity of α-Chymotrypsin in Cationic Surfactant Solutions: The Component Specificity Revisited.

Enhanced catalytic activity (super activity) of enzymes in the presence of surfactants is of key importance in "micellar enzymology"; such super activity is not very trivial, it is highly system specific, and the mechanism behind the activity enhancement is not always well apprehended. We report the catalytic activity of α-chymotrypsin (CHT) on ala-ala-phe-7-amido-4-methylcoumarin (AMC) in the presence of cationic surfactants of different hydrophobic chain lengths: dodecyltrimethylammonium bromide (DTAB), cetyltrimethylammonium bromide (CTAB) and octadecyltrimethylammonium bromide (OTAB). It is observed that in comparison to buffer the catalytic activity of CHT is enhanced 5-fold in premicellar DTAB solutions, while negligible changes are observed in CTAB and OTAB.

Non-monotonic dynamics of water in its binary mixture with 1,2-dimethoxy ethane: A combined THz spectroscopic and MD simulation study.

A combined experimental (mid- and far-infrared FTIR spectroscopy and THz time domain spectroscopy (TTDS) (0.3-1.6 THz)) and molecular dynamics (MD) simulation technique are used to understand the evolution of the structure and dynamics of water in its binary mixture with 1,2-dimethoxy ethane (DME) over the entire concentration range.

Effect of Short Chain Poly(ethylene glycol)s on the Hydration Structure and Dynamics around Human Serum Albumin.

We report the changes in the hydration dynamics around a globular protein, human serum albumin (HSA), in the presence of two short chain crowding agents, namely poly(ethylene glycol)s (PEG 200 and 400). The change in the network water structure is investigated using FTIR spectroscopy in the far-infrared (FIR) frequency range. Site specific changes are obtained by time-resolved fluorescence spectroscopic technique using the intrinsic fluorophore tryptophan (Trp214) of HSA.

Micelle induced dissociation of DNA-ligand complexes: The effect of ligand binding specificity.

We investigate the SDS micelle induced dissociation of a small fluorescent ligand 4',6-diamidino-2-phenylindole (DAPI) bound to DNAs of varying sequences. Steady state and time resolved fluorescence measurements affirm minor groove binding of DAPI to poly(dA).poly(dT) and calf thymus DNA while it intercalates in poly(dG).

Does urea alter the collective hydrogen-bond dynamics in water? A dielectric relaxation study in the terahertz-frequency region.

We report the ultrafast collective hydrogen-bond dynamics of water in the extended hydration layer of urea by using terahertz time-domain spectroscopy in the frequency region of 0.3-2.0 THz.

Collective hydration dynamics of guanidinium chloride solutions and its possible role in protein denaturation: a terahertz spectroscopic study.

The remarkable ability of guanidinium chloride (GdmCl) to denature proteins is a well studied yet controversial phenomenon; the exact molecular mechanism is still debatable, especially the role of hydration dynamics, which has been paid less attention. In the present contribution, we have addressed the issue of whether the collective hydrogen bond dynamics of water gets perturbed in the presence of GdmCl and its possible impact on the denaturation of a globular protein human serum albumin (HSA), using terahertz (THz) time domain spectroscopy (TTDS) in the frequency range of 0.3-2.

Short chain polyethylene glycols unusually assist thermal unfolding of human serum albumin.

In the present study we have investigated the thermal stability of the globular transport protein human serum albumin (HSA), in the presence of two small chain polyethylene glycols (namely PEG 200 and PEG 400). Both near- and far-UV circular dichroism (CD) study reveal that addition of PEG moderately increases the α-helical content of the protein without abruptly changing its tertiary structure. The hydration structure at the protein surface experiences a notable change at 30% PEG (v/v) concentration as evidenced from compressibility and dynamic light scattering (DLS) measurements.