Mónika Zsuzsanna Bokor

Wigner Fizikai Kutatóközpont · Experimental solid state physics

Parkinson's disease is thought to be caused by aggregation of the intrinsically disordered protein, α-synuclein. Two amyloidogenic variants, A30P, and E46K familial mutants were investigated by wide-line 1H NMR spectrometry as a completion of our earlier work on wild-type and A53T α-synuclein (Bokor M. et al. WT and A53T α-synuclein systems: meltin...

The amount of bonds between constituting parts of a protein aggregate were determined in wild type (WT) and A53T α-synuclein (αS) oligomers, amyloids and in the complex of thymosin-β4–cytoplasmic domain of stabilin-2 (Tβ4-stabilin CTD). A53T αS aggregates have more extensive βsheet contents reflected by constant regions at low potential barriers in...

Secondary structure predictions of proteins were compared to experimental results by wide-line ¹H NMR. IUPred2A was used to generate predictions of disordered protein or binding regions. Thymosin-β4 and the stabilin-2 cytoplasmic domain were found to be mainly disordered, in agreement with the experimental results. α-Synuclein variants were predict...

The potential barriers governing the motions of α-synuclein (αS) variants’ hydration water, especially energetics of them, is in the focus of the work. The thermodynamical approach yielded essential information about distributions and heights of the potential barriers. The proteins’ structural disorder was measured by ratios of heterogeneous water-...

Wide‐line 1 H NMR measurements were extended and all results were interpreted in a thermodynamics based new approach on aqueous solutions of thymosin‐β 4 (Tβ 4 ), stabilin C‐terminal domain (CTD) and their 1:1 complex. Energy distributions of potential barriers controlling the motion of protein‐bound water molecules were determined. Heterogeneous a...

Parkinson’s disease is connected with abnormal α -synuclein ( α S) aggregation. Energetics of potential barriers governing motions of hydration water is examined. Information about the distributions and heights of potential barriers is gained by a thermodynamical approach. The ratios of the heterogeneous water-binding interfaces measure proteins’ s...

Hydration properties of folded and unfolded/disordered miniproteins were monitored in frozen solutions by wide-line 1H-NMR. The amount of mobile water as function of T (−80 °C < T < 0 °C) was found characteristically different for folded (TC5b), semi-folded (pH < 3, TCb5(H+)) and disordered (TC5b_N1R) variants. Comparing results of wide-line 1H-NMR...

Here we present a novel method for the characterization of the hydration of protein solutions based on measuring and evaluating two-component wide-line 1H NMR signals. We also provide a description of key elements of the procedure conceived for the thermodynamic interpretation of such results. These interdependent experimental and theoretical treat...

Wide-line 1H NMR measurements were extended and all results were reinterpreted in a thermodynamics based new approach on aqueous solutions of thymosin-β4 (Tβ4), stabilin C-terminal domain (CTD) and their 1:1 complex. The energy distributions of the potential barriers, which control motion of protein-bound water molecules, were determined. Heterogen...

In this work we lay the groundwork of characterizing the mobility of hydrogen-hydrogen pairs (proton-proton radial vectors) in proteins in the solid state that contains only residual water. In this novel approach we introduce new ways of analyzing and interpreting data, by: i) representing hydrogen mobility (HM) and melting diagram (MD) data record...

We report the synthesis, structure, and superconducting properties of single crystals of SmFeAsOHx. The crystals were grown at high pressure and high temperature using a cubic anvil technique. H1−NMR studies confirm the presence of H atoms in the samples. Single crystal x-ray diffraction analyses demonstrate a remarkable disorder in the Sm2O2 layer...

Wide-line 1H NMR intensity and differential scanning calorimetry measurements were carried out on the intrinsically disordered 73-residue full transactivation domain (TAD) of p53 tumor suppressor protein and two peptides, one a wild type p53 TAD peptide with a helix pre-structuring property and a mutant peptide with a disabled helix-forming propens...

We present compelling evidence pointing to the possible synthesis of unconventional C66 and C68 fullerenes in the interior of single-walled carbon nanotubes. The production proceeds from C60-toluene/benzene clathrates encapsulated inside the nanotubes using heat-driven nanotesttube chemistry. All isomers violate the so-called isolated pentagon rule...

Reductive hydrogenation was applied to two types of single-walled carbon nanotubes with different diameter range. Alkali metal intercalation, followed by reaction with methanol, led to hydrogenated products. Both yield and selectivity of this reaction showed strong dependence on diameter, contrary to expectation based on simple curvature effects. T...

The mobility of the proton-proton radial vectors is introduced as a quantitative measure for the structural dynamics of organic materials, especially protein molecules. As defined for the entire molecule, the hydrogen mobility (HM) is proposed as an “order parameter,” which describes the effect of motional narrowing on inter-proton dipole-dipole in...

Thymosine β4 (Tβ4) is a 43 amino acid long intrinsically disordered protein (IDP), which was initially identified as an actin-binding and sequestering molecule. Later it was described to have multiple other functions, such as regulation of endothelial cell differentiation, blood vessel formation, wound repair, cardiac cell migration, and survival.1...

Human nucleolar phosphoprotein p140 (hNopp 140) is a highly phosphorylated protein inhibitor of casein kinase 2 (CK2). As in the case of many kinase-inhibitor systems, the inhibitor has been described to belong to the family of intrinsically disordered proteins (IDPs), which often utilize transient structural elements to bind their cognate enzyme....

In this chapter, the reader is introduced to the basics of wide-line NMR, with particular focus on the following: (1) basic theoretical and experimental NMR elements, necessary before switching the spectrometer and designing the experiment, (2) models/theories for the interpretation of measured data, (3) definition of wide-line NMR spectrometry, th...

The propensity of α-synuclein to form amyloid plays an important role in Parkinson's disease. Three familial mutations, A30P, E46K, and A53T, correlate with Parkinson's disease. Therefore, unraveling the structural effects of these mutations has basic implications in understanding the molecular basis of the disease. Here, we address this issue thro...

The principal aim of our work is to characterize structural and dynamical properties of interfacial water at the protein surface by wide - line NMR spectroscopy and nuclear relaxation time measurements for the identification and characterization of intrinsically disordered proteins (IDPs) and to make a distinction between IDPs and globular proteins...

Wide-line (1)H NMR signal intensity, spin-lattice and spin-spin relaxation rates and differential scanning calorimetry (DSC) measurements were done on avian (chicken and turkey) crystalline lenses between -70 degrees C and +45 degrees C to provide quantitative measures of protein hydration characteristic of the protein-water interfacial region. The...

The rotor–stator molecular cocrystal C60·C8H8 (fullerene–cubane) has been investigated by 13C nuclear magnetic resonance (NMR). The room-temperature spectrum obtained using 1H–13C cross-polarization technique shows two lines with chemical shifts identical with the shifts of the original molecular constituents demonstrating the lack of a strong elec...

CASK-interactive protein1 is a newly recognized post-synaptic density protein in mammalian neurons. Although its N-terminal region contains several well-known functional domains, its entire C-terminal proline-rich region of 800 amino acids lacks detectable sequence homology to any previously characterized protein. We used multiple techniques for th...

Wide-line 1H-NMR and differential scanning calorimetry measurements were done in aqueous solutions and on lyophilized samples of human ubiquitin between -70 degrees C and +45 degrees C. The measured properties (size, thermal evolution, and wide-line NMR spectra) of the protein-water interfacial region are substantially different in the double-disti...

We have investigated the rotor-stator molecular crystal fullerene-cubane (C60 · C8H8) by 1H NMR spectroscopy in the temperature range of 130 to 380 K. The 1H line is broad and exhibits fine structure characteristic of a multispin spectrum, indicating the absence of angular reorientations of the cubane molecule. The temperature and field dependence...

Protein disorder is predicted to be widespread in eukaryotic proteomes, although direct experimental evidence is rather limited so far. To fill this gap and to unveil the identity of novel intrinsically disordered proteins (IDPs), proteomic methods that combine 2D electrophoresis with mass spectrometry have been developed. Here, we applied the meth...

The paper presents the experimental results of rigid-lattice proton magnetic resonance spectra and second moments in Pd–H, Pd0.90Ag0.10–H, Pd0.80Ag0.20–H, Pd0.75Ag0.25–H, and Pd0.65Ag0.35–H alloys at T = 2.4 K in a wide hydrogen concentration range. Free induction decay (FID), solid and inhomogeneous echoes were detected and interpreted. The interp...

We report on 1H NMR of (NixMn1-x) 3[Cr(CN)6]2 ·15H2O hexacyanochromates, where x changes from 0 to 1. The decay time constants of the free induction decay signals described by an effective spin-spin relaxation time T2cff obtained from M(t) -Mo exp(t/T2eff) decrease as the local magnetic moments increase produced by the magnetic transition metal ion...

We report on H-1 NMR of (NixMn1-x)(3)[Cr(Cn)(6)](2) center dot nH(2)O hexacyanochromates, where x changes from 0 to 1. The decay time constants of the free induction decay signals described by an effective spin-spin relaxation time T-2eff obtained from M(t) = M-0 exp(t/T-2eff) decrease as the local magnetic moments increase produced by the magnetic...

The fraction of mobile (unfrozen) water during phase transitions of NaCl–H2O solution and tris(hydroxymethyl)aminomethane (Tris) buffer solution has been determined by differential scanning calorimetry (DSC). Measurements were carried out in the temperature range between −50 and +30°C with a heating rate of 2Kmin−1. The fraction of mobile water was...

Simultaneous realisation of hydrogen charging or discharging process and in situ measurements of different NMR characteristic quantities give outstanding chances for the investigation and understanding of local physical properties of and hydrogen diffusion in disordered metal-hydrogen systems, including both equilibrium and non-equilibrium states....

Proton NMR intensity and differential scanning calorimetry measurements were carried out on an intrinsically unstructured late embryogenesis abundant protein, ERD10, the globular BSA, and various buffer solutions to characterize water and ion binding of proteins by this novel combination of experimental approaches. By quantifying the number of hydr...

We report on magnetic properties of bimetallic extended networks built from [WIV(CN)8]4- and TM2+ = Mn2+ , Fe2+, Co2+, Ni2+, Cu2+ , Zn2+. The weak exchange interaction is the reason for appearance of magnetically ordered state at low temperatures for all compounds with exception of Zn2[W(CN)8].nH2O. It has been shown that susceptibility data for al...

Crystalline Pd1−xAgx–Hy (x=0–0.35) alloys were studied as model systems representing a chemically disordered system for hydrogen-storage materials. Extensive relaxation rate (R1, R1ρ and R2) measurements were carried out in a wide temperature range of 2.4–400 K. Palladium–silver alloys of silver concentration as high as 35 at.% were studied by NMR...

Cubane (C8H8) and fullerene (C60) are famous cage molecules with shapes of platonic or archimedean solids. Their remarkable chemical and solid-state properties have induced great scientific interest. Both materials form polymorphic crystals of molecules with variable orientational ordering. The idea of intercalating fullerene with cubane was raised...

We present sidewall functionalization of carbon nanotubes via various dis-solving metal reduction methods. Carbanion complexes of lithium were prepared in liquid ammonia and THF and reacted with a series of alkyl and aryl halogenides, as well as methanol resulting in the formations of alkylated, arylated, and hydrogenated nanotube derivatives, resp...

Intrinsically unstructured proteins (IUPs) exist in a disordered conformational state, often considered to be equivalent with the random-coil structure. We challenge this simplifying view by limited proteolysis, circular dichroism (CD) spectroscopy, and solid-state (1)H NMR, to show short- and long-range structural organization in two IUPs, the fir...

Intrinsically unstructured/disordered proteins (IUPs) exist in a disordered and largely solvent-exposed, still functional, structural state under physiological conditions. As their function is often directly linked with structural disorder, understanding their structure-function relationship in detail is a great challenge to structural biology. In...

Octacyanomolybdates (OCMs) TM2+2[Mo(CN) 8·nH2O, where TM is Mn, Fe, Co, Ni, Cu were synthesised and characterised by IR spectroscopy and UV-VIS spectroscopy. The UV-VIS spectrum showed the intervalence charge transfer (IVCT) band between MoIV-CN-CuII and MoV-CN-CuI around 510 nm. Studied OCMs adopt tetragonal crystal structure. The 1H NMR signals r...

Octacyanomolybdates (OCMs) TM2 divided by[Mo(CN)(8)]center dot nHO, where TM is Mn, Fe, Co, Ni, Cu were synthesised and characterised by IR spectroscopy and UV-VIS spectroscopy. The UV-VIS spectrum showed the intervalence charge transfer (IVCT) band between Mo-IV-CN-Cu-II and Mo-V-CN-Cu-I around 510 nm. Studied OCMs adopt tetragonal crystal structu...

The 1 H NMR spectroscopic analysis and magnetization measurements were performed on TM 22+[MoIV(CN)8].nH2O compounds (TM=Mn, Fe, Co, Ni, Cu, VO). The 1 H NMR signals reflect the magnetic moment of the TM ions (μ P). The decay rates of FID signals increase as μ P and the applied static rf field increase. The spin-lattice relaxation times at 27.7 MHz...

Quadrupole effects in room-temperature continuous-wave (CW)63Cu nuclear magnetic resonance (NMR) spectra, “π/2” pulse length shortening and amplitudes of two-pulse generated echoes were investigated on nanocrystalline copper powders produced by cryogenic melting and by ball milling techniques. Systematic measurements on the parent polycrystalline c...

In-situ hydrogen charging (discharging) process was realized in Pd0.75Ag0.25–H alloys and simultaneous hydrogen concentration and nuclear spin-spin relaxation time measurements were done. Concentration-gradient driven diffusion coefficient was estimated from the hydrogen concentration-charging (discharging) time curve and data for the intrinsic dif...

In-situ hydrogen charging (discharging) process was realized in Pd 0.75Ag0.25-H alloys and simultaneous hydrogen concentration and nuclear spin-spin relaxation time measurements were done. Concentration-gradient driven diffusion coefficient was estimated from the hydrogen concentration-charging (discharging) time curve and data for the intrinsic di...

A systematic NMR study was performed on several alkyl–tetrazole complexes of iron(II) and zinc(II) in the 10–300 K temperature range. The experiments were designed to separate the electronic and reorientational phase transitions caused by the spin crossover of the iron compounds from those independent of unpaired electrons. The 19F spectral data on...

The Ce, Pr, Sm, Gd, Dy and Ho ferricyanides have been synthesized by procedure similar to that of Prandtl and Mohr [1]. The powder samples were characterized by means of IR spectroscopy utilizing frequency range of 4000 - 450 cm-1. Thermal gravimetric analysis was carried out to determine the number of associated water molecules per formula unit. S...

Magnetic properties of Prussian blue analogues, the molecule-based ferrimagnet Pr[Fe(CN)6] · 5H2O, are presented. The zero-field-cooled magnetisation curves deviate from the field-cooled magnetisation measurements M(T) below certain temperature Tf = 14.5 K, and show a broad maximum at about T = 12 K. Such a behaviour of M(T) is typical for the smal...

The partition of hydrogen into diffusible and residual parts was realized by pulse NMR spectroscopy, by gas chromatography and by prompt gamma activation analysis (PGAA). The total hydrogen content was determined by the two non-NMR methods and the diffusible (mobile) component by CPMG NMR pulse sequence. Results on amorphous Ni(Cu)–Zr–H systems of...

Quasi-elastic neutron scattering measurements were performed on aqueous solutions of 3-picoline (3-methylpyridine) at room temperature. H-D substitution on both the solute and the water was used to separate the dynamics of the two species. The analysis of the translational diffusive motion at different concentrations shows that at high picoline con...

1H NMR spectra of the spin-crossover compound [Fe(ptz)6](BF4)2 and its zinc(II) analogue were recorded on polycrystalline samples as the function of decreasing temperature in order to study the connection of the change in the electronic state and the molecular motions present in both crystals. The temperature range for the zinc compound was 295–30...

19 F and 11 B spin-lattice relaxation times were measured in [ Zn ( ptz ) 6 ] ( BF 4 ) 2 and in the spin-crossover compound [ Fe ( ptz ) 6 ] ( BF 4 ) 2 . For both compounds BF 4 - anion reorientation is active above 50 K. For [ Zn ( ptz ) 6 ] ( BF 4 ) 2 , the anion-reorientation dynamics is different in the temperature regions...

19F and 11B spin-lattice relaxation times were measured in [Zn(ptz)6](BF4)2 (ptz = 1-n-propyl-1H-tetrazole) and in the spin-crossover compound [Fe(ptz)6](BF4)2. For both compounds BF-4 anion reorientation is active above 50 K. For [Zn(ptz)6](BF4)2, the anion-reorientation dynamics is different in the temperature regions of 50-90 K, 90-120 K, and ab...

The applicability of positron annihilation spectroscopy for chemical structural problems is demonstrated by two examples: For the swelling dynamics of an amphiphilic polymer network, very quick structural changes were indicated by positronium lifetime parameters at very low swelling ratios and a hydration mechanism was proposed accordingly. For the...

Positron lifetime parameters were measured for the spin-crossover complexes [Fe(R-1 H-tetrazole)6](BF4)2 (R = 1-ethyl, 1-n-propyl) and for the diamagnetic [Zn(1-n-propyl-1 H-tetrazole)6](BF4)2. Positronium forms with significant intensity in the studied compounds. The ortho-para conversion of ortho-positronium was used to follow the spin-crossover....

Our work proves that positron annihilation spectroscopy is an excellent tool to follow the structural changes in chemical species. We present four examples to support the above statement. The sizes of defects in electrodeposited chromium layers were studied and estimated on the basis of positron lifetime spectra decomposed into two components. Vaca...

Positron lifetime parameters were measured for the spin-crossover complexes [Fe(1-alkyl-1H-tetrazole)6](BF4)2 and [Fe(1,10-phenathroline)2(NCS)2]. If there are structural free volumes large enough (as for [Fe(1-ethyl-1H-tetrazole)6](BF4)2 and Fe(1-propyl-1H-tetrazole)6](BF4)2), there is a significant intensity of positronium (Ps) and the lifetime o...

Positron lifetime parameters were measured for the spin-crossover complexes [Fe(1-alkyl-1H-tetrazole)(6)](BF(4))(2) and [Fe(1,10-phenathroline)(2)(NCS)(2)]. If there are structural free volumes large enough (as for [Fe(1-ethyl-1H-tetrazole)(6)](BF(4))(2) and Fe(1-propyl-1H-tetrazole)(6)](BF(4))(2)), there is a significant intensity of positronium (...

Positron lifetime and 1H spin-lattice relaxation time measurements for 1-alkyl-1H-tetrazole Fe2+ and Zn2+ complexes showed that the activation of certain intramolecular motions and the temperature of the spin-crossover (for Fe2+ complexes) are in close relation. For the zinc-propyltetrazole complex a structural change is detectable around 70 K by b...

PMR linewidths (Δν) and spin-lattice relaxation times (T1) were measured on [M(1-n-propyl-1H-tetrazole)6](BF4)2 (M is Zn or Fe). Three motional minima of T1 associated with steps of Δν were found, and a structural change in the temperature region of 100 to 120 K is suggested in the zinc complex. The spin transition temperature was found to be ∼130...

The complexes [Zn(1-propyltetraole)6](BF4)2 (Zn-ptz) and [Fe(methyltetrazole)6](BF4)2 (Fe-mtz) were investigated by positron annihilation and solid-state NMR spectroscopy. For Zn-ptz signs of structural rearrangements were found between 70 and 145 K. For the spin-crossover complex Fe-mtz a transition affecting the high-spin stat Fe2+ ions at lattic...

Proton spin–lattice relaxation times were measured between 2.2 K and room temperature in [Zn(ptz)6](BF4)2(ptz = 1-n-propyl-1H-tetrazole) and in the spin-crossover complex [Fe(ptz)6](BF4)2. Three different types of intramolecular motion of the propyl group are suggested in [Zn(ptz)6](BF4)2, namely tunneling and classical rotation of methyl groups an...

Positron lifetime spectroscopic and Dopplerbroadening measurements have been carried out on trans-stilbene single crystals. The results (including the complementary DSC measurement) give new evidence for the existence of phase transitions in trans-stilbene at temperatures between 20 and 300 K.

Az alap- és adalék-anyagok mennyiségének meghatározására YAB minták össze-hasonlító analízisét készítettük el lángatomabszorpciós és induktivan csatolt plazma atomemissziós spektrometriával. A YAB kristályba Mo, K, Ca, Si, Ti, Na, Mg, Fe, és Zn idegen elemeket tartalmazó mikrozárványok nőnek be, egyéb kristályhibák kialakulásához vezetve. EPR vizsg...

Elméleti vizsgálatainkban az kérdeztük, hogyan vezethetnek a geometriai kényszerek, a magasabb spinkicserélődés, illetve az anizotróp kölcsönhatások szokatlan tulajdonságú mágneses fázisokhoz. Megmutattuk, hogy 1-es spinű kvantumrendszerekben nemmágneses, mégis O(3) szimmetriát sértő kvadrupoláris rend jöhet létre bikvadratikus kölcsönhatás jelenlé...