Nanoparticles present enormous surface areas and are found to enhance the rate of protein fibrillation by decreasing lag time for nucleation. Protein is involved in many human diseases, including Alzheimer's, Creutzfeld-Jacob disease, dialysis-related amyloidosis. Fibril formation occurs nucleation-dependent kinetics, wherein a critical nucleus key rate-determining step, after which proceeds rapidly. We show that nanoparticles (copolymer particles, cerium oxide quantum dots, carbon...

Copolymeric NiPAM:BAM nanoparticles of varying hydrophobicity were found to retard fibrillation the Alzheimer's disease-associated amyloid β protein (Aβ). We that these affect mainly nucleation step Aβ fibrillation. The elongation is largely unaffected by particles, and once nucleated, process occurs with same rate as in absence nanoparticles. extension lag phase for strongly dependent on both amount surface character Surface plasmon resonance studies show binds provide equilibrium constants...

The fibrillation kinetics of the amyloid β peptide is analyzed in presence cationic polystyrene nanoparticles different size. results highlight importance ratio between and particle concentration. Depending on specific ratio, kinetic effects vary from acceleration process by reducing lag phase at low surface area solution to inhibition high area. behavior can be explained if we assume a balance two pathways: first free monomer second nucleation promoted surface. overall rate will depend...

Nanoparticles interfere with protein amyloid formation. Catalysis of the process may occur due to increased local concentration and nucleation on nanoparticle surface, whereas tight binding or a large particle/protein surface area lead inhibition aggregation. Here we show clear correlation between intrinsic stability effect aggregation rate. The results were reached for series five mutants single-chain monellin differing in toward denaturation, which propensity has been previously documented...

The fibrillation process of the islet amyloid polypeptide (IAPP) and its fragment (IAPP(20−29)) was studied by means Thioflavin T (ThT) fluorescence transmission electron microscopy in absence presence N-isopropylacrylamide:N-tert-butylacrylamide (NiPAM:BAM) copolymeric nanoparticles. found to be strongly affected nanoparticles, which retard protein as a function chemical surface properties NiPAM:BAM ratio varied from 50:50 100:0. nanoparticles with higher fraction NiPAM imposed strongest...

Diffusion measurements by nuclear magnetic resonance (NMR) spectroscopy were used to investigate the host-guest association between beta-cyclodextrin (CD) and alkyltrimethylammonium bromide surfactants with different chain lengths, ranging from 6 up 16 carbons. The scope limitations of method in study formation inclusion complexes are discussed. influences presence CD micellization process have been studied, apparent critical micellar concentration self-diffusion coefficients species present...

The aggregation of amyloid β peptides (Aβ) into fibrils is implicated in the pathology Alzheimer's disease. In light increasing number proteins reported to retard Aβ fibril formation, we investigated influence small hydrophilic model different charge on kinetics and their interaction with Aβ. We followed formation Aβ40 Aβ42 using thioflavin T fluorescence presence six variants calbindin D9k single-chain monellin. was verified transmission electron microscopy. observe retardation process from...

The dynamics of the protein unfolding and adsorption is dominated by nature surface which define driving forces energy barriers process.

The interaction between beta-cyclodextrin (CD) and gemini surfactant of the type alkyl-alpha,omega-bis(dodecyldimethylammonium bromide) with different spacer lengths 2, 8, 10 carbons has been investigated by means electric conductivity (EC) proton self-diffusion NMR at 298 K. formation a 2:1 (CD:gemini) complex in two-step mechanism is observed first association constant (K(11)) higher than second one (K(21)), but both relatively small comparison single C(12)-tailed surfactant. value...

The fibril formation of the neurodegenerative peptide amyloid β (Aβ42) is sensitive to solution conditions, and several proteins peptides have been found retard process. Aβ42 was followed with ThT fluorescence in presence polyamino acids (poly-glutamic acid, poly-lysine, poly-threonine) other polymers (poly(acrylic acid), poly(ethylenimine), poly(diallyldimethylammonium chloride). An accelerating effect on aggregation process observed from all positively charged polymers, while no seen...

Amyloid fibrils are the most distinct components of plaques associated with various neurodegenerative diseases. Kinetic studies amyloid fibril formation shed light on microscopic mechanisms that underlie this process as well contributions internal and external factors to interplay between different mechanistic steps. Thioflavin T is a widely used noncovalent fluorescent probe for monitoring formation; however, it may suffer from limitations due unspecific interactions dye additives. Here, we...

The enzymatic activity of human carbonic anhydrase II (HCAII) was studied in the presence nanoparticles different nature and charge. Negatively charged inhibit HCAII whereas no effect is seen for positively particles. kinetic effects were correlated with strength binding enzyme to particle surface as measured by ITC adsorption assays. Moreover, conformational changes upon observed circular dichroism. main initial driving force electrostatic hydrophobic not strong enough drive binding. This...

The size of the anisotropic domains in a lyotropic liquid crystal is estimated using new protocol for diffusion NMR. Echo attenuation decays are recorded different durations displacement-encoding gradient pulses, while keeping effective time and range wave vectors constant. Deviations between sets data appear if there non-Gaussian processes occurring on time-scale defined by pulse duration length-scale vector. homogeneous as minimum which appears to be Gaussian. Simulations performed show...

The chemical behavior of β-cyclodextrin/nonionic surfactant mixed systems has been investigated using the basic hydrolysis N-methyl-N-nitroso-p-toluenesulfonamide as a probe. experimental results prove that at cmc, there are significant quantities uncomplexed β-CD in equilibrium with micellar aggregates. In contrast to expected situation, percentage system increases on increasing hydrophobicity molecule. This is due existence two simultaneous processes: complexation monomers by cyclodextrin...

A kinetic study was carried out on various solvolytic reactions in water/ NH4OT /isooctane microemulsions. The surfactant is a derivative of the sodium salt bis(2-ethylhexyl) sulfosuccinate (NaOT or AOT), where Na+ counterion has been replaced by NH4+. substitution effects phase diagram system, and therefore, NH4OT-based microemulsions with high water content reaching values W = 350 (W [H2O]/[NH4OT]) can be obtained. presence suggests transition microemulsion microstructure from water-in-oil...

The solvolysis of substituted benzoyl chlorides is sensitive both to substituent electronic effects and medium effects. reactions have been analyzed in the presence nonionic micelles. reaction inhibited or catalyzed depending on mechanism, dissociative associative, respectively. micellar observed can be related low water content polarity interface as well an increase nucleophilic character interfacial water. Moreover, effect surface charge mechanism with high associative was systematically...

The solvolysis reactivity of benzoyl chlorides entails a high sensitivity on medium properties. A systematic study the reaction series these substrates, varying electron-withdrawing character substituent, has been performed in nonionic microemulsions. kinetic effects due to variation microemulsion compositions can be assigned modifications system properties, precise, interface Microemulsion properties that are obtained from analysis show good agreement with characterization was made via 1H...

A series of recent studies have provided initial evidence about the role specific intra-molecular interactions in maintaining proteins their soluble state and protecting them from aggregation. Here we show that amino acid sequence protein monellin contains two aggregation-prone regions are prevented initiating aggregation by multiple non-covalent favor burial within folded protein. By investigating behavior single-chain a five its mutational variants using variety biochemical, biophysical...

In this contribution the influence of β-cyclodextrin (CD) on behavior aqueous systems containing vesicles dipalmitoyl phosphatidyl choline (DPPC) has been studied by determining kinetics solvolysis reaction substituted benzoyl chlorides whose reactivity entails a high sensitivity media properties. The application pseudophase formalism allowed us to obtain thermodynamic and kinetic coefficients characteristic reaction, which are essentially independent concentration CD. We were able determine...

Rate constants are reported for the pH-independent hydrolysis of 4-methoxyphenyl-2,2-dichloroethanoate in aqueous solution as a function concentration added cyanomethane (acetonitrile), polyethylene glycol (PEG 400) and tetrahydrofuran (THF). The water was varied between ca. 25 55.5 M. It found that variation activity yields only minor contribution to observed rate constants. Interestingly, both PEG 400 log(k) varies approximately linearly with molar water. Medium effects highly solutions...