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Wide-line 1 H NMR measurements were extended and all results were interpreted in a thermodynamics-based new approach on aqueous solutions of thymosin-β4 (Tβ4 ), stabilin cytoplasmic domain (CTD), and their 1 : 1 complex. Energy distributions of potential barriers controlling the motion of protein-bound water molecules were determined. Heterogeneous and homogeneous regions were found in the protein-water interface. The measure of heterogeneity of this interface gives quantitative value for the portion of disordered parts in the protein. Ordered structural elements were found extending up to ∼20 % of the individual whole proteins. About 40 % of the binding sites of free Tβ4 get involved in bonds holding the complex together. The complex has the most heterogeneous solvent accessible surface (SAS) in terms of protein-water interactions. The complex is more disordered than Tβ4 or stabilin CTD. The greater SAS area of the complex is interpreted as a clear sign of its open structure.

Wide-line (1) H NMR measurements were extended and all results were reinterpreted in a new thermodynamics-based approach to study aqueous solutions of thymosin-beta4 (Tbeta4 ), 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. Heterogeneous and homogeneous regions were found at the protein-water interface. The measure of heterogeneity gives a quantitative value for the portion of disordered parts in the protein. Ordered structural elements were found extending up to 20 % of the whole proteins. About 40 % of the binding sites of free Tbeta4 become involved in bonds holding the complex together. The complex has the most heterogeneous solvent accessible surface (SAS) in terms of protein-water interactions. The complex is more disordered than Tbeta4 or stabilin CTD. The greater SAS area of the complex is interpreted as a clear sign of its open structure.

The potential barriers governing the motions of &alpha, synuclein (&alpha, S) variants&rsquo, 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&rsquo, structural disorder was measured by ratios of heterogeneous water-binding interfaces. They showed the &alpha, S monomers, oligomers and amyloids to possess secondary structural elements, although monomers are intrinsically disordered. Despite their disordered nature, monomers have 33% secondary structure, and therefore they are more compact than a random coil. At the lowest potential barriers with mobile hydration water, monomers are already functional, a monolayer of mobile hydration water is surrounding them. Monomers realize all possible hydrogen bonds with the solvent water. &alpha, S oligomers and amyloids have half of the mobile hydration water amount than monomers because aggregation involves less mobile hydration. The solvent-accessible surface of the oligomers is ordered or homogenous in its interactions with water to 66%. As a contrast, &alpha, S amyloids are disordered or heterogeneous to 75% of their solvent accessible surface and both wild type and A53T amyloids show identical, low-level hydration. Mobile water molecules in the first hydration shell of amyloids are the weakest bound compared to other forms.

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 1H-NMR and molecular dynamics simulations we found that both the amount of mobile water surrounding proteins in ice, as well as their thaw profiles differs significantly as function of the compactness and conformational heterogeneity of their structure. We found that (i) at around −50 °C ~50 H2Os/protein melt (ii) if the protein is well-folded then this amount of mobile water remains quasi-constant up to −20 °C, (iii) if disordered then the quantity of the lubricating mobile water increases with T in a constant manner up to ~200 H2Os/protein by reaching −20 °C. Especially in the −55 °C ↔ −15 °C temperature range, wide-line 1H-NMR detects the heterogeneity of protein fold, providing the size of the hydration shell surrounding the accessible conformers at a given temperature. Results indicate that freezing of protein solutions proceeds by the gradual selection of the enthalpically most favored states that also minimize the number of bridging waters.

Wide-line (1) H NMR measurements were extended and all results were reinterpreted in a new thermodynamics-based approach to study aqueous solutions of thymosin-beta4 (Tbeta4 ), 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. Heterogeneous and homogeneous regions were found at the protein-water interface. The measure of heterogeneity gives a quantitative value for the portion of disordered parts in the protein. Ordered structural elements were found extending up to 20 % of the whole proteins. About 40 % of the binding sites of free Tbeta4 become involved in bonds holding the complex together. The complex has the most heterogeneous solvent accessible surface (SAS) in terms of protein-water interactions. The complex is more disordered than Tbeta4 or stabilin CTD. The greater SAS area of the complex is interpreted as a clear sign of its open structure.

Wide-line 1H NMR intensity and differential scanning calorimetry measurements were carried out on the intrinsically disordered 73-residue full transactivation domain (TAD) of the 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 propensity. Measurements were carried out in order to characterize their water and ion binding characteristics. By quantifying the number of hydrate water molecules, we provide a microscopic description for the interactions of water with a wild-type p53 TAD and two p53 TAD peptides. The results provide direct evidence that intrinsically disordered proteins (IDPs) and a less structured peptide not only have a higher hydration capacity than globular proteins, but are also able to bind a larger amount of charged solute ions. [BMB Reports 2016; 49(9): 497-501].

The experimental characterization of hindered-rotation barriers and mapping the energetic heterogeneity of water molecules bound to the molecular “surface” of proteins is critical for understanding the functional interaction of proteins with their environment. Here, we show how to achieve this goal by an original wide-line NMR procedure, which is based on the spectral motional narrowing phenomenon following the melting (thawing) process of interfacial ice. The procedure highlights the differences between globular and intrinsically disordered proteins and it enables to delineate the effect of solvent on protein structure, making a distinction between point mutants, monomeric and oligomeric states, and characterizing the molecular interactions taking part in different cellular processes. We put this unique experimental approach introducing novel physical quantities and quantifying the heterogeneous distribution of motional activation energy of water in the interfacial landscape into a historical perspective, demonstrating its utility through a variety of globular and disordered proteins.

In this work the groundwork is laid for characterizing the mobility of hydrogen-hydrogen pairs (proton-proton radial vectors) in proteins in the solid state that contain only residual water. In this novel approach, we introduce new ways of analyzing and interpreting data: 1) by representing hydrogen mobility (HM) and melting diagram (MD) data recorded by wide-line 1 H NMR spectroscopic analysis as a function of fundamental temperature (thermal excitation energy); 2) by suggesting a novel mode of interpretation of these parameters that sheds light on details of protein-water interactions, such as the exact amount of water molecules and the distribution of barrier potentials pertaining to their rotational and surface translational mobility; 3) by relying on directly determined physical observables. We illustrate the power of this approach by studying the behavior of two proteins, the structured enzyme lysozyme and the intrinsically disordered ERD14.

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 through comparing details of the hydration of wild-type α-synuclein and its A53T mutant by a combination of wide-line NMR, differential scanning calorimetry, and molecular dynamics simulations. All three approaches suggest a hydrate shell compatible with a largely disordered state of both proteins. Its fine details, however, are different, with the mutant displaying a somewhat higher level of hydration, suggesting a bias to more open structures, favorable for protein-protein interactions leading to amyloid formation. These differences disappear in the amyloid state, suggesting basically the same surface topology, irrespective of the initial monomeric state.

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. These measures are of paramount importance in understanding both the physiology of crystalline lens and its transitions to the cataractous pathological state characterized by the formation of opaque protein aggregates. Water mobility shows a characteristic transition at about -60 degrees C, which is identified as the melting of the interfacial/hydrate water. The amount of water in the low-temperature mobile fraction is about h = 0.4 g water/g protein, which equals the hydration required for protein activity. The amount of mobile water is temperature-independent up to about -10 degrees C, with a significant increase at higher temperatures below 0 degrees C. Above 0 degrees C, the relaxation processes can be described by a single (for spin-lattice) and by a triple (for spin-spin relaxation) exponential function. The spin-spin relaxation rate component of R(2) = 10-20 s(-1) and its dynamical parameters characterize the interfacial water at ambient or physiological temperatures. When considered an independent phase, the specific heat of the hydrate water obtained by a combination of DSC and NMR data in the temperature range -43 degrees C to -28 degrees C is higher than that of pure/bulk water. This discrepancy can only be resolved by assuming that the hydrate water is in strong thermodynamic coupling with the protein matrix. The specific heat for the system composed of the protein molecule and its hydration water is 4.6 +/- 0.3 J g(-1) K(-1). Thus, in a thermodynamic sense, crystalline protein and its hydrate layer behave as a highly-interconnected single phase.

The paper presents the experimental results of rigid-lattice proton magnetic resonance spectra and second moments in Pd–H, Pd 0.90 Ag 0.10 –H, Pd 0.80 Ag 0.20 –H, Pd 0.75 Ag 0.25 –H, and Pd 0.65 Ag 0.35 –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 interpretation based on dipole–dipole interaction of homogeneously distributed proton spin system is satisfactory at high hydrogen concentration, but an inhomogeneous field of paramagnetic origin (most probably coming from Fe impurities) plays the dominant role at small hydrogen content. An unexpected correlation was found between the macroscopic magnetic susceptibility and the second moment coming from the inhomogeneous internal field.

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 2 K min −1 . The fraction of mobile water was estimated from the enthalpy of melting of the different frozen phases present in aqueous solution samples. Results are supplemented by proton NMR intensity measurements in the same temperature range. A small endothermic peak was detected in the DSC curves at the same temperature where the change in the NMR intensity occurs. We assume that activation/deactivation of rotational molecular motion of hydration water molecules occurs at the steps of the NMR intensity at higher and lower temperatures during heating and cooling, respectively. The rotational motion is probably the initial stage of the eutectic phase separation. Tris additive to NaCl solution causes thermal shifts of the small endothermic peak and in the related NMR intensity. These qualitative differences indicate interactions of Na + and Cl − ions with the small organic molecule constituents.

Crystalline Pd 1-x Ag x -H y (x = 0-0.35) alloys were studied as model systems representing a chemically disordered system for hydrogen-storage materials. Extensive 1 H relaxation rate (R 1 , R 1p and R 2 ) 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 spectroscopy for the first time. The relaxation mechanisms magnetic dipolar relaxation (hydrogen diffusion), Korringa relaxation, relaxation by paramagnetic impurity ions and cross-relaxation to quadrupolar metal nuclei were identified and characterized. The presence of cross-relaxation between 1 H and quadrupolar 105 Pd nuclear spins was assumed and demonstrated for the first time in Pd-H and Pd 1-x Ag x -H systems. More than one jump processes of diffusing hydrogen were found to be present in the studied palladium-silver alloys. Only lower estimated limit values of Korringa constants could be obtained since no frequency independent R 1 versus T region was found. These values are significantly higher than the ones reported by others.

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 particular, their hydration and residual structure, both closely linked with their mechanism of action, require close attention. Here we demonstrate that the hydration of IUPs can be adequately approached by a technique so far unexplored with respect to IUPs, solid-state NMR relaxation measurements. This technique provides quantitative information on various features of hydrate water bound to these proteins. By freezing nonhydrate (bulk) water out, we have been able to measure free induction decays pertaining to protons of bound water from which the amount of hydrate water, its activation energy, and correlation times could be calculated. Thus, for three IUPs, the first inhibitory domain of calpastatin, microtubule-associated protein 2c, and plant dehydrin early responsive to dehydration 10, we demonstrate that they bind a significantly larger amount of water than globular proteins, whereas their suboptimal hydration and relaxation parameters are correlated with their differing modes of function. The theoretical treatment and experimental approach presented in this article may have general utility in characterizing proteins that belong to this novel structural class.

In this work, the electrochemical hydrogen doping and withdrawal process of Pd metal was examined with respect to the applicability of Faraday’s law. It was found that after a suitable electrolytic pre-treatment, the normalized resistivity ( R / R 0 ) versus hydrogen concentration ( c F = H/M) curves where c F was determined from Faraday’s law by assuming that the 100% current efficiency is independent of the value of the applied charging current density in a wide range. In the α-Pd(H) phase (up to c (α max ) = 0.015H/M), a good quantitative agreement was found with previous resistivity studies by both electrolytic and gas-phase charging. However, for c > c (α max ) our R / R 0 versus c F data did not agree with the R / R 0 versus c H curve from previously reported electrochemical charging experiments of Pd metal where the doped amount of hydrogen, c H , was determined by direct methods. The two sets of resistivity data can be brought into good agreement by assuming that the current efficiency for the absorption process is η a = 1.55. Similarly, for the electrolytic desorption process, an agreement with the previously reported R / R 0 versus c H curve could be achieved by taking η d = 1.9. These current efficiency values higher than unity would imply that each hydrogen absorbed/desorbed by electrolytic charge/discharge processes is accompanied by the absorption/desorption of some excess H atoms by processes not requiring electric charge transfer (i.e., only neutral H atoms are involved). At present, we do not have a physical/chemical picture about the nature of such processes.

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 different compositions are shown. Partially crystallized samples were also studied as an extension. A method proposed by us directly gives the fractional population of hydrogen atoms in the free (mobile) state on the spin–spin relaxation time scale. On the other hand the least values of the residual hydrogen content correlate surprisingly well with the numbers of filled four Zr-type H-sites calculated by Batalla et al. [NATO ASI Ser. 136 (1985) 203] for 0.21-nm exclusion distance.

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 propyl-tetrazole compounds show that the electronic spin-transition has a strong effect on the spectra, and their behavior can be explained as a combined response to molecular reorientations and the spin transition. For these complexes, second-moment calculations revealed the strength of the interaction between resonant and nonresonant nuclei. Both of the applied NMR methods show irregularities at the temperature region between 70 and 120 K, suggesting the presence of a phase transition. The data also suggest two kinds of reorientational behavior for the BF4 − counter ions. In the iron–ethyl–tetrazole compound, unlike in the propyl–tetrazole complex, a significant amount of unpaired electrons remains in their original high-temperature HS state. Above their effect, the behavior of the nuclear spins of the iron compound is basically governed by the same structural factors as in its zinc analog. The two-exponential behavior of the 1H-T 1 in case of the zinc–methyl–tetrazole compound can be explained on the basis of cross relaxation with the 19F nuclei due to the low 1H/19F ratio. The presence of the two types of methyl reorientation is assumed to be the sign of the two different lattice sites known to be present in the FeII compound. The single-exponential T 1 above T c in the case of [Fe(mtz)6](BF4)2 is consistently the sign of the strength of the paramagnetic relaxation observed in the ethyl and propyl compounds.

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. The observed yield, as detected by thermogravimetry-mass spectroscopy and 1H-NMR, is drastically reduced in small-diameter tubes where the alkali dopant does not reach the inside of the bundles. Wide range optical transmission measurements were employed to determine the selectivity and indicate that besides higher yield, lower diameter selectivity occurs above a critical diameter., 14 pages, 4 figures

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 dis- ordered metal-hydrogen systems, including both equilibrium and non-equilibrium states. A few selected preliminary experimental results are presented in this letter for Pd0.9Ag0.1-H al- loy on in situ hydrogen concentration, proton NMR line-shift and magnetic susceptibility, 1 H NMR spectrum, spin-spin relaxation time and hydrogen diffusion activation energy and cor- relation time measurements. The motional averaged spectrum is asymmetric and the possible decompositions relate to the non-single-site residence of hydrogen in this alloy. Introduction. - Feenstra et al. (1) recently proposed to consider hydrogen embedded in a metallic lattice as a "local probe" for the investigation of local properties of hydrogen containing disordered alloys. In this concept Solomons and co-workers (2) used thermodynamic data of hydrogen absorption for Pd-Ag-H alloys and a multi-site lattice-gas model for the determination of site energies of hydrogen located in the centre of Pd1−xAgx octahedron, and the terminology of "hydrogen spectroscopy" was introduced by them. The Pd-Ag alloys are probably the simplest and consequently the best representatives of the chemically disordered alloys, they were subjects of widespread experimental and the- oretical investigations (see, e.g., (3-5) and references therein). The atomic size of the two alloying elements are nearly the same in this system, and Pd and Ag form homogenous solid solution of face-centred-cubic (fcc) structure in the whole concentration range. The hydrogen solubilities for the pure metals differ by many orders of magnitude, so the local distribution of constituents (probably binomial) could strongly affect the microscopic physical properties, too. The magnetic susceptibility of pure Pd is reduced by both silver and hydrogen addition demonstrating the change of the electron structure. The other properties, which are impor- tant in this context, i.e. hydrogen solubility, hydrogen diffusivity, nuclear magnetic relaxation rates, also depend on the composition. NMR —as is well known— is one of the most widely applied local methods, and hydrogen nuclei serve a priori as local probes for the investigation of different microscopic properties

The paper presents the results of an experimental investigation of rigid-lattice proton magnetic resonance (PMR) spectra and second moments in Ni 0.67 Zr 0.33 –H, Ni 0.50 Zr 0.50 –H, Ni 0.33 Zr 0.67 –H binary glassy alloy–hydrogen systems in the range of hydrogen-per-metal ( H / M ) ratio of 0.14≤ H / M ≤1.9. The line shape can be described by the empirical Harper-Barnes function with exponent values ranging from 1.45 to 2.95 in the whole hydrogen concentration range. The generally assumed Gaussian form is valid in a narrow H / M interval only. The second moment as a function of H / M can be fitted by a power function of an exponent 3/4. The exponent is independent of the composition of the alloy. We found that a simple lattice gas model based on a homogeneous hydrogen distribution contradicts the experimental results. Instead, a short-range order model has been proposed in which the hydrogen atoms are located in the centres of distorted tetrahedra of metal atoms, that is in the basic building blocks of the amorphous alloys. The Switendick criterion was also taken into consideration. We have shown that few proton first neighbours (0–2) and a small number of second neighbours (1–8), that is, a cluster of hydrogen is sufficient to account for the measured value of the second moment. Ternary Zr 0.5 Ni 0.5− x Cu x –H alloys have been investigated, too. The addition of Cu nuclei did not lead to the second moment enhancement expected for a homogeneous distribution of components.

Results of electrical resistance measurements are given on Pd80 Ag20 alloy during hydrogen uptake from gaseous H2 atmosphere and from liquid electrolyte by cathodic charging. For both cases in the course of a monotonous increase of the hydrogen concentration in the alloy, the electrical resistivity shows anomalous behavior. These kinetic curves reflect the effect of phase changes in the non-equilibrium state. The ‘non-equilibrium’ expression is used in this entire work in the sense that no care was taken in waiting for the stable value of resistivity after any partial filling, but the resistivity was frequently measured while the sample was continuously charged with hydrogen. A model has been proposed for the interpretation of the experimental findings.

A systematic study on nuclear spin–spin relaxation of water protons in human, fish and bird eye lenses/lens nuclei is reported. The purpose of this study is to clarify the real nature of the relaxation processes not describable as a single exponential decay. The characterization of the spin–spin relaxation by a single exponential is commonly used both in literature and in MRI diagnostics. However, in our opinion, this single exponential decay hypothesis is an oversimplification that can lead to the loss of essential information. Our measurements were performed by Carr–Purcell–Meiboom–Gill (CPMG) pulse sequences on human, carp, chicken and turkey eye lenses/lens nuclei. Several hundreds of CPMG echo amplitude were detected and the time-dependence of their decay was determined by careful fitting procedures. Our results clearly rule out the single exponential decay hypothesis for eye lenses: at least two or three decaying components are observed. These phenomena need further investigations: it should be decided which of the relaxation parameters, T 2I -s and A i -s gives the most characteristic physiological or pathological information. It is claimed that the amplitude ratio of the bound and the free water fraction carries the most characteristic information. During the cataract formation the weight of free water is raised by more than 25%.

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 K, with a cooling rate of ∼1 K min−1, while in the case of the iron(II) compound this temperature range was 298–10 K with the same cooling rate as in the case of [Zn(ptz)6](BF4)2. The analysis of the temperature dependence of the line shape parameters and calculations of 1H second moments showed the following. The temperature of the spin transition in the iron(II) compound is 132 K on cooling. On the basis of the similarity of the temperatures at which the different molecular motions appear, the same motions are present in both compounds in the whole temperature range. The [Zn(ptz)6](BF4)2 probably goes through a structural transition between 90 and 60 K, this transition manifests in the virtual increase of the average proton–proton distance, and the sign of a similar transition is also observed in [Fe(ptz)6](BF4)2.

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 of 50-90 K, 90-120 K, and above 150 K; between 120 and 150 K it changes rapidly reflecting a structural change. In [ Fe ( ptz ) 6 ] ( BF 4 ) 2 the mechanism for the paramagnetic relaxation involving the 19 F nuclei is found to be of the diffusion-limited type according to the theory of Lowe and Tse. The present results prove that the spin-crossover takes place in a dynamic surrounding and not in a static crystal lattice.

We have investigated the rotor-stator molecular crystal fullerene-cubane (C 60 .C 8 H 8 ) by 1 H'NMR spectroscopy in the temperature range of 130 to 380 K. The 1 H 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 of the spin-lattice relaxation rate of cubane protons is well explained in terms of field fluctuations arising from reorientations of the C 60 molecules. Despite the closely packed structure, the activation energy of these reorientations, 650 K, is close to that observed in the high-temperature phase of pure C 60 indicating that the static cubane molecules act as efficient bearing for the rotating fullerene molecules.

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. Vacancies, di-vacancies and vacancy-clusters could be identified in the electrodeposites. The changes of the size distribution of the free volume units in poly(methylmetacrylate) on the dependence of molecular weight and dispersity were described by the correlation between the lifetime ofortho-Ps and the free volume units in polymers. It was found that the free volume is affected by both the molecular weight and dispersity. The effect of dispersity was explained by the sample preparation technique, namely by the application of high pressure. The ortho-para conversion ofortho-Ps was used to follow the partial spin-crossover in [Fe(1-ethyl-1H-tetrazole)6](BF4)2. The spin-crossover temperature was identified to be 105 K. A conformal structural transformation was found in [Zn(1-propyl-1H-tetrazole)6](BF4)2 between 170 and 90 K by positronium lifetime measurement and the role of (BF4)2− anion, in this transformation, was proved by19F NMR spectroscopy.

The hydrogen charging and discharging processes are investigated in Ni67−xCuxZr33 glassy alloys by in situ resistance measurements in order to clarify the surface and bulk contribution to the activation process. The process has been monitored by conventional DC method using a computer-controlled system, exposing the samples to hydrogen at pressure from 0.1–8.6 MPa at temperatures of 293 K and 393 K. The H-contents (H/M) were determined by weight and by pulse NMR measurements. The NMR data are obtained by the Carr–Purcell–Meiboom–Gill (CPMG) method. The charging is extremely long and the resulting H-distribution is inhomogenous during the first cycle, especially at 293 K. This fact shows the significance of the surface-activation during the H-uptake from the gas phase. The duration of the second saturation decreases significantly, and the resistance–time curves obtained: on two parallel samples are very similar. The saturation value for the normalized resistance (R/R0) remains almost the same during several cycles. Increasing the temperature of the charging (393 K), the equilibrium value of the resistance decreases. The resistance of the samples at the end of the discharging process is always higher than before charging. This indicates the partial irreversibility of the H-absorption at constant temperature. This observation is correlated with the NMR results.

1 H spin–spin relaxation time ( T 2 ) and complementary hydrogen content, PMR spectrum width and spin–lattice relaxation time ( T 1 ) have been measured in Zr y (Ni 1− x Cu x ) 1− y –H ternary amorphous alloys of different hydrogen content at 0≤ x ≤33 at.% Cu and y =33, 50 and 67 at.% Zr concentrations using Carr–Purcell–Meiboom–Gill (CPMG), solid-echo and saturation recovery pulse sequences, respectively. At high hydrogen contents the T 2 measured by the slope of the CPMG echo train depends on both the Zr and Cu content, but is independent of the hydrogen content. The differences in the spin–spin relaxation behaviours can be attributed to the substantial change of correlation time and not to the change of activation energy or local fields. The measurements were made in the “motional narrowing” state, consequently our E a and τ ∞ quantities are averaged to the diffusion motion of protons taking part in this process. At small hydrogen contents T 2 depends on hydrogen content and the T 2 vs. 1/ T curves cannot be fitted by single Arrhenius plots. The hydrogen content measured by echo train has turned out to be systematically smaller than that measured by weight increase, demonstrating that not all the hydrogen takes part in the diffusion process.

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 interactions. HM satisfies all requirements of an order parameter in the Landau molecular field theory of phase transitions. The wide-line NMR second moments needed to obtain HM are exactly defined and measurable physical quantities, which are not produced by mathematical fitting and do not carry the limitations and restrictions of any model (theoretical formalism). We first demonstrate the usefulness of HM on small organic molecules with data taken form the literature. We outline its link with structural and functional characteristics on a range of proteins: HM provides a model-free parameter based on first principles that can clearly distinguish between globular and intrinsically disordered proteins, and can also provide insight into the behavior of disease-related mutants.

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 lattice site B occurs below 15 K.

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 and rotation of methylene groups. Correlation times and activation energies are calculated for tunneling rotation of the CH3group and for the classical (hindered) rotations of –CH3and –CH2–CH3as reorientations over a three-well asymmetrical potential. In [Fe(ptz)6](BF4)2the mechanism for the paramagnetic relaxation is found to be of the rapid-diffusion type according to the theory of Lowe and Tse, and the intramolecular motions are suggested to be the same as for the zinc complex.

A two-exponential spin-lattice ( T 1 ) relaxation process of hydrogen nuclear magnetization was found in a series of hydrogenated amorphous carbon samples prepared under different self-bias conditions from benzene. The temperature dependence of these relaxation times reveals the different dynamic background of the two sub-systems. Low activation energies (depending on self-bias voltages) were measured for the longer relaxation time components; temperature independence was detected for the shorter relaxation time components.

Spin-spin relaxation time ( T 2 ) and complementary hydrogen content (H/M), PMR spectrum width (FWHM) and spin lattice relaxation time ( T 1 ) have been measured in (Ni 1 − x Cu x ) 0.5 Zr 0.5 -H y ternary amorphous alloys at 0 ⩽ x ⩽ 29 at.% concentrations using Carr-Purcell-Meiboom-Gill (CPMG), solid-echo and saturation recovery pulse sequences respectively. The T 2 relaxation time measured by the slope of the CPMG echo train depends on both the hydrogen and Cu content. The dependence can be attributed to the change of correlation time and not to the change of activation energy or local field. The measurements were made in the ‘motional narrowing’ state; consequently our E a and τ ∞ quantities are averaged to the diffusional motion of protons taking part in this process. The extrapolated amplitude of the echo train measured on the alloy-hydrogen system and normalized to the same quantity in water, gives the value of proton magnetization in thermal equilibrium, that is the hydrogen content free from any perturbing effects. The hydrogen content measured by CPMG echo train has turned out to be systematically smaller than that measured by weight increase.

Equilibrium pressure and potential measurements at room temperature as a function of hydrogen concentration are reported for Ni 1− x Zr x amorphous alloys with 0.33 ⩽ x ⩽ 0.45. The full range of charge of the samples was achieved by taking into account the hydrogen gas evolved in the closed electrochemical cell. The change in slope of the equilibrium potential with the state of charge shows that different types of site are filled. On the basis of the pressure-composition (P-C) diagrams, the samples with x = 0.33, 0.36 and 0.39 were selected for further electrochemical investigations.

The aim of this paper is to reinvestigate the proton magnetic resonance spectra in Zr 0.5 Ni 0.5− y Cu y H x metallic glasses. Solid-echo pulse sequences were used to analyze the line shape. The measurements were made in the temperature range 2.2–300 K and at a frequency of 87.6 MHz. The reinvestigation of the line shape mostly at low temperatures was initiated after having realized that the splitting reported earlier on our samples was a consequence of the relatively long recovery time of our spectrometer. The present solid-echo measurements yielded simple spectra describable by a Harper-Barnes line shape close to gaussian.

The proton NMR line shift with respect to water, the bulk susceptibility and in a few cases the Korringa contribution to the spin lattice relaxation time were measured in Zr0.33Ni0.67 Hx amorphous alloys with hydrogen concentration 0.1 ⩽ x ⩽ 0.7and at 343 K. All the parameters, including the hydrogen content and the bulk susceptibility, were measured simultaneously in situ, and in the shift measurements a resolution of ±1 ppm was attained. The residual Knight shift depends on the hydrogen content and is positive relative to water. Preliminary low temperature spin lattice relaxation time measurements indicate that the positive shift is the consequence of the balance of s- and d-contributions.

Proton magnetic resonance spectra of Zr 0.5 Cu y Ni 0.5−y H 1 metallic glass samples with 0 ≤ y ≤ 0.3 were measured in the temperature range 77 K to 400 K and at 8, 28.5, 87.6 and 88.5 MHz frequencies. The data of the free-induction decay (FID) signal were compiled and Fourier transformed by a SMIS NMR spectrometer. The temperature dependence of the line shapes shows three distinctly different features: (i) in the temperature range 400 K to 270 K the spectrum is a motionally narrowed Lorentzian line; (ii) in the temperature range 270 K to 140 K the spectrum consists of a narrow Lorentzian component and a substantially wider Gaussian one; (iii) in the temperature range 140 K to 77 K, the spectrum is a “two-peaked” line. The distance between the two peaks (splitting) was found to be independent of the temperature and the frequency, that means that the low-temperature spectrum is probably the Pake doublet of hydrogen pairs. From the analysis of the splitting of the Pake doublet, a proton-proton distance of 0.167 nm was estimated. This distance corresponds to a transition metal mediated hydrogen pairing.

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 the structural characterization of this region and its three fragments. By bioinformatics predictions, CD spectroscopy, wide-line and 1H-NMR spectroscopy, limited proteolysis and gel filtration chromatography, we provided evidence that the entire proline-rich region of CASK-interactive protein1 is intrinsically disordered. We also showed that the proline-rich region is biochemically functional, as it interacts with the adaptor protein Abl-interactor-2. To extend the finding of a high level of disorder in this scaffold protein, we collected 74 scaffold proteins (also including proteins denoted as anchor and docking), and predicted their disorder by three different algorithms. We found that a very high fraction (53.6% on average) of the residues fall into local disorder and their ordered domains are connected by linker regions which are mostly disordered (64.5% on average). Because of this high frequency of disorder, the usual design of scaffold proteins of short globular domains (86 amino acids on average) connected by longer linker regions (140 amino acids on average) and the noted binding functions of these regions in both CASK-interactive protein1 and the other proteins studied, we suggest that structurally disordered regions prevail and play key recognition roles in scaffold proteins. Structured digital abstract • MINT-7034649: Caskin1 (uniprotkb:Q8VHK2) physically interacts (MI:0915) with L1CAM (uniprotkb:P32004) by two hybrid (MI:0018) • MINT-7034677: Caskin1 (uniprotkb:Q8VHK2) physically interacts (MI:0915) with NCK1 (uniprotkb:P16333) by two hybrid (MI:0018) • MINT-7034706: Caskin1 (uniprotkb:Q8VHK2) physically interacts (MI:0915) with Stathmin-3 (uniprotkb:Q9NZ72) by two hybrid (MI:0018) • MINT-7034579: Caskin1 (uniprotkb:Q8VHK2) physically interacts (MI:0915) with ABI2 (uniprotkb:Q9NYB9) by two hybrid (MI:0018) • MINT-7034720: Caskin1 (uniprotkb:Q8VHK2) physically interacts (MI:0915) with Synaptotagmin (uniprotkb:P21579) by two hybrid (MI:0018) • MINT-7034691: Caskin1 (uniprotkb:Q8VHK2) physically interacts (MI:0915) with Neurexin-2 (uniprotkb:Q9P2S2) by two hybrid (MI:0018) • MINT-7034617: Caskin1 (uniprotkb:Q8VHK2) physically interacts (MI:0915) with CASK (uniprotkb:P07498) by two hybrid (MI:0018) • MINT-7034748: Caskin1 (uniprotkb:Q8VHK2) physically interacts (MI:0915) with SIAH1 (uniprotkb:Q8IUQ4) by two hybrid (MI:0018) • MINT-7034663: Caskin1 (uniprotkb:Q8VHK2) physically interacts (MI:0915) with Myosin-Ib (uniprotkb:O43795) by two hybrid (MI:0018) • MINT-7034734: Caskin1 (uniprotkb:Q8VHK2) physically interacts (MI:0915) with Septin-4 (uniprotkb:O43236) by two hybrid (MI:0018) • MINT-7034634: Caskin1 (uniprotkb:Q8VHK2) physically interacts (MI:0915) with EPHA2 (uniprotkb:P29317) by two hybrid (MI:0018) • MINT-7034765, MINT-7034783: Caskin1 (uniprotkb:Q8VHK2) physically interacts (MI:0915) with ABI2 (uniprotkb:Q9NYB9) by pull down (MI:0096)

The time evolution of the hydrogen absorption of melt-quenched Zr50Ni50 amorphous alloy ribbons was investigated for the as-quenched state and after a relaxation heat treatment. Hydriding was performed from the gas phase at 200 °C and 35 atm H2 gas pressure for charging times up to t = 48 h. The absorption process was monitored by measuring the mass increase, the thermoelectric power and the magnetization of the hydrided ribbons. For both the as-quenched and relaxed state, homogeneously hydrided ribbons could only be obtained at small ( H M ) and high ( H M ≈ 1 ) hydrogen contents. The maximum amount of absorbed hydrogen was found to be the same for both states; however, the hydrogen absorption process in the relaxed ribbons required considerably longer times than for the as-quenched state. As in our previous study of a Zr47.5Ni52.5 metallic glass, the magnetization measurements indicated also for the present alloy the occurrence of a phase separation process leading to the development of strongly magnetic nickel-rich clusters for long charging times.

The influence of hydrogen on some physical properties and on the micro-structure of a nearly equiatomic, melt-quenched NiZr amorphous alloy was investigated. Hydrogen absorption from the gas phase at 190 °C and 35–40 atm pressure was measured by weight as a function of the charging time. Considerable hydrogen absorption occurred only for charging times around 10 h and was completed within a few hours. The hydrogen content remained constant for a hydrogen-to-metal ratio of about one for prolonged charging. The room-temperature thermopower changed considerably upon hydriding and a local thermopower probe revealed that the activation time varies considerably along the ribbon length. It was found that, during further heat treatment in a hydrogen gas atmosphere after a hydrogen-to-metal ratio of approximately one was reached, the magnetic state of the amorphous NiZr samples changed progressively from paramagnetic to superparamagnetic. The density and size of the magnetic clusters, which were nickel-rich segregations induced by the hydriding process, were determined by magnetic and scanning transmission electron microscopic measurements. After desorbing hydrogen at elevated temperatures, magnetic measurements indicated the disappearance of the superparamagnetic clusters.

Accurate measurements of small 31P Knight shift effects in crystalline Ni3P and Cu3P alloys have been performed by using a magic-angle spinning (MAS) nuclear magnetic resonance (NMR) technique. Both the average Knight shift and the width of its distribution have been found to be different when comparing a normal (equilibrium) and a melt-quenched Ni3P alloy and this is attributed to possible differences in defect concentration and grain size. The 31P NMR line shift of Cu3P is much smaller (K=0.012%) than that of Ni3P (K=0.179%) but spin-lattice relaxation time measurements indicated a Korringa-type relaxation mechanism for both alloys, i.e. Cu3P has also a metallic character.

The proton rotating-frame spin lattice relaxation time T1r has been measured in (Ni0.5Zr0.5)0.95P0.05H0.54 and (Ni0.5Zr0.5)Po0.07H0.58 amorphous alloys in the temperature range 140–370 K. A single-exponential relaxation decay was obtained from 200 to 370 K only. The experimental data above 200 K were interpreted on the basis of a model involving diffusion of the hydrogen atoms. It is demonstrated that, by using a gaussian distribution of diffusion activation energies about a temperature independent mean energy E a = 0.32 eV atom−1 and a full width at half maximum ΔE = 0.07 eV, the temperature dependence of T1r can be well fitted in the 200–370 K range. These values are compared with relevant hydrogen diffusion data from the literature on other amorphous alloys

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 K, and an anomalous minimum of T1 occurred at 9 K in the iron complex.

Results of resistivity measurements during electrolytical hydrogen charging on some Fe, Co and Ni based alloy ribbons in amorphous, nanocrystalline and body-centred cubic state are presented. The peculiarities of the H uptake are significantly different for the different structural modifications of alloys with the same chemical composition. In the limited concentration interval of equality of the transferred charge and the number of actually absorbed hydrogen atoms, the concentration variation of the resistivity increment caused by unit hydrogen concentration was determined.

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 several years ago but no attempts at preparation have been reported. Here we show that C60 and similarly C70 form high-symmetry molecular crystals with cubane owing to topological molecular recognition between the convex surface of fullerenes and the concave cubane. Static cubane occupies the octahedral voids of the face-centred-cubic structures and acts as a bearing between the rotating fullerene molecules. The smooth contact of the rotor and stator molecules decreases significantly the temperature of orientational ordering. These materials have great topochemical importance: at elevated temperatures they transform to high-stability covalent derivatives although preserving their crystalline appearance. The size-dependent molecular recognition promises selective formation of related structures with higher fullerenes and/or substituted cubanes.

The proton content in Zr 0.33 Ni 0.67 H x amorphous alloy was monitored by changes in electrical resistivity and with the extraplated spin echo amplitude measured by the Carr-Purcell-Meiboom-Gill (CPMG) nuclear magnetic resonance pulse sequence in the temperature interval 300 to 450 K. Both methods show that the hydrogen desorption processes can be approximately divided into two ranges. The first is a fast process which is at present not interpretable. In the second stage, the process is thermally activated, and the activation energy calcualted from the resistivity changes is equal to 0.32 ± 0.04 eV. The CPMG spin echo measurements also give the spin-spin relaxation time of diffusing protons and the activation energy of this process, 0.34 ± 0.02 eV, is exactly the same as extracted from the resistivity measurements.

Results of electrical resistance measurements are given on Pd80 Ag20 alloy during hydrogen uptake from gaseous H2 atmosphere and from liquid electrolyte by cathodic charging. For both cases in the course of a monotonous increase of the hydrogen concentration in the alloy, the electrical resistivity shows anomalous behavior. These kinetic curves reflect the effect of phase changes in the non-equilibrium state. The ‘non-equilibrium’ expression is used in this entire work in the sense that no care was taken in waiting for the stable value of resistivity after any partial filling, but the resistivity was frequently measured while the sample was continuously charged with hydrogen. A model has been proposed for the interpretation of the experimental findings.