Dependence Of Chemical Shifts Research Articles

NH2(CH3)2CuCl3 Organic-Inorganic Hybrid Perovskite: Consideration to Crystal Structure, Thermodynamics, and Structural Molecular Dynamics.

The crystal structure of NH2(CH3)2CuCl3, an organic-inorganic hybrid perovskite, undergoes a phase transition from triclinic to monoclinic at the phase transition temperature T C of 287 K. We investigated the temperature dependencies of NMR chemical shifts and spin-lattice relaxation time T 1ρ to gain insights into the structural geometry and molecular dynamics during the transition from phase II to phase I at high temperatures. Analysis of the 1H and 13C NMR chemical shifts of the cation revealed a continuous change in the surrounding structural geometry with temperature, without any anomalous changes around T C. The sudden decrease in T 1ρ values from low to high temperatures indicated a significant variation in proton and carbon dynamics at T C, arising from the slowing motion of molecular dynamics across the phase transition. The activation energies E a obtained from the temperature dependence of T 1ρ for 1H and 13C were larger in phase I than in phase II. This suggests that molecular motions in phase II exhibit a higher degree of freedom compared to those in phase I, where they are more constrained. These findings on NH2(CH3)2CuCl3 are presented to enhance its potential applications by elucidating the crystal configuration and structural molecular dynamics of ABX3 type compound.

Plasticity of the proteasome-targeting signal Fat10 enhances substrate degradation.

The proteasome controls levels of most cellular proteins, and its activity is regulated under stress, quiescence, and inflammation. However, factors determining the proteasomal degradation rate remain poorly understood. Proteasome substrates are conjugated with small proteins (tags) like ubiquitin and Fat10 to target them to the proteasome. It is unclear if the structural plasticity of proteasome-targeting tags can influence substrate degradation. Fat10 is upregulated during inflammation, and its substrates undergo rapid proteasomal degradation. We report that the degradation rate of Fat10 substrates critically depends on the structural plasticity of Fat10. While the ubiquitin tag is recycled at the proteasome, Fat10 is degraded with the substrate. Our results suggest significantly lower thermodynamic stability and faster mechanical unfolding in Fat10 compared to ubiquitin. Long-range salt bridges are absent in the Fat10 structure, creating a plastic protein with partially unstructured regions suitable for proteasome engagement. Fat10 plasticity destabilizes substrates significantly and creates partially unstructured regions in the substrate to enhance degradation. NMR-relaxation-derived order parameters and temperature dependence of chemical shifts identify the Fat10-induced partially unstructured regions in the substrate, which correlated excellently to Fat10-substrate contacts, suggesting that the tag-substrate collision destabilizes the substrate. These results highlight a strong dependence of proteasomal degradation on the structural plasticity and thermodynamic properties of the proteasome-targeting tags.

Five Hypotheses on the Origins of Temperature Dependence of 77Se NMR Shifts in Diselenides.

Notable thermal shifts in diselenides have been documented in 77Se NMR for more than 50 years, but no satisfactory explanation has been found. Here, five hypotheses are considered as possible explanations for the large temperature dependence of the 77Se chemical shifts of diaryl and dialkyl diselenides compared to monoselenides and selenols. Density functional theory calculations are provided to bolster hypotheses and better understand the effects of barrier height and dipole energies. It is proposed that the temperature dependence of diselenide 77Se NMR chemical shifts is due to rotation around the Se-Se bond and sampling of twisted conformers at higher temperatures. The molecular twisting is solvent dependent; here, DMSO-d6 and toluene-d8 were evaluated. No correlation was established between para-substituents on diaryl diselenides and the magnitude of the change in the 77Se NMR shift (Δδ) with temperature.

Including the Ensemble of Unstructured Conformations in the Analysis of Protein's Native State by High-Pressure NMR Spectroscopy.

The analysis of pressure induced changes in the chemical shift of proteins allows statements on structural fluctuations proteins exhibit at ambient pressure. The inherent issue of separating general pressure effects from structural related effects on the pressure dependence of chemical shifts has so far been addressed by considering the characteristics of random coil peptides on increasing pressure. In this work, chemically and pressure denatured states of the cold shock protein B from Bacillus subtilis (BsCspB) have been assigned in 2D 1H-15N HSQC NMR spectra and their dependence on increasing hydrostatic pressure has been evaluated. The pressure denatured polypeptide chain has been used to separate general from structural related effects on 1H and 15N chemical shifts of native BsCspB and the implications on the interpretation of pressure induced changes in the chemical shift regarding the structure of BsCspB are discussed. It has been found that the ensemble of unstructured conformations of BsCspB shows different responses to increasing pressure than random coil peptides do. Thus, the approach used for considering the general effects that arise when hydrostatic pressure increases changes the structural conclusions that are drawn from high pressure NMR spectroscopic experiments that rely on the analysis of chemical shifts.

Analyse des Nativen Zustands von Proteinen durch Hochdruck NMR‐Spektroskopie unter Berücksichtigung des Ensembles Unstrukturierter Konformationen

AbstractDie Analyse druckabhängiger Änderungen der chemischen Verschiebung von Proteinen erlaubt es, Aussagen über strukturelle Fluktuationen zu machen, die diese bereits bei Umgebungsdruck aufweisen. Das Problem, allgemeine Effekte, die mit einer Erhöhung des hydrostatischen Drucks einhergehen, von strukturell bedingten Effekten auf die chemische Verschiebung zu trennen, wurde bisher durch das Einbeziehen der Eigenschaften unstrukturierter Modellpeptide angegangen. In dieser Arbeit wurden chemische Verschiebungen in 2D 1H‐15N‐HSQC Spektren von chemisch als auch druckdenaturierten Zuständen des Kälteschockproteins B aus Bacillus Subtilis (BsCspB) zugeordnet und ihre Abhängigkeit von Änderungen des hydrostatischen Drucks ausgewertet. Die durch hydrostatischen Druck denaturierte Polypeptidkette wurde verwendet, um allgemeine Effekte von strukturbedingten Effekten auf 1H und 15N chemische Verschiebungen zu trennen. Daraus resultierende Interpretationen der druckabhängigen Änderungen der chemischen Verschiebungen werden im strukturellen Kontext diskutiert. Es wurde festgestellt, dass das Ensemble unstrukturierter Konformationen von BsCspB anders auf eine Erhöhung des Drucks reagiert, als es unstrukturierte Modellpeptide tun. Daraus kann geschlussfolgert werden, dass der Ansatz, mit dem man allgemeine Effekte, die durch eine Erhöhung des Drucks hervorgerufen werden, abschätzt, die strukturellen Rückschlüsse ändert, die anhand einer Analyse von chemischen Verschiebungen getroffen werden.

On the geometry dependence of the nuclear magnetic resonance chemical shift of mercury in thiolate complexes: A relativistic density functional theory study.

Thiolate containing mercury(II) complexes of the general formula [Hg(SR) ] have been of great interest since the toxicity of mercury was recognized. 199Hg nuclear magnetic resonance spectroscopy (NMR) is a powerful tool for characterization of mercury complexes. In this work, the Hg shielding constants in a series of [Hg(SR) ] complexes are therefore investigated computationally with particular emphasis on their geometry dependence. Geometry optimizations and NMR chemical shift calculations are performed at the density functional theory (DFT) level with both the zeroth-order regular approximation (ZORA) and four-component relativistic methods. The four exchange-correlation (XC) functionals PBE0, PBE, B3LYP, and BLYP are used in combination with either Dyall's Gaussian-type (GTO) or Slater-type orbitals (STOs) basis sets. Comparing ZORA and four-component calculations, one observes that the calculated shielding constants for a given molecular geometry have a constant difference of 1070 ppm. This confirms that ZORA is an acceptable relativistic method to compute NMR chemical shifts. The combinations of four-component/PBE0/v3z and ZORA/PBE0/QZ4P are applied to explore the geometry dependence of the isotropic shielding. For a given coordination number, the distance between mercury and sulfur is the key factor affecting the shielding constant, while changes in bond and dihedral angles and even different side groups have relatively little impact.

Structure, dynamics, and redox reactivity of an all-purpose flavodoxin

The flavodoxin of Rhodopseudomonas palustris CGA009 (Rp9Fld) supplies highly reducing equivalents to crucial enzymes such as hydrogenase, especially when the organism is iron-restricted. By acquiring those electrons from photodriven electron flow via the bifurcating electron transfer flavoprotein (ETF), Rp9Fld provides solar power to vital metabolic processes. To understand Rp9Fld's ability to work with diverse partners, we solved its crystal structure. We observe the canonical flavodoxin (Fld) fold and features common to other long-chain Flds, but not all the surface loops thought to recognize partner proteins. Moreover some of the loops display alternative structures and dynamics. To advance studies of protein-protein associations and conformational consequences, we assigned the 19F NMR signals of all 5 tyrosines (Tyrs). Our electrochemical measurements show that incorporation of 3-19F-Tyr in place of Tyr has only a modest effect on Rp9Fld's redox properties even though Tyrs flank the flavin on both sides. Meanwhile, the 19F probes demonstrate the expected paramagnetic effect, with signals from nearby Tyrs becoming broadened beyond detection when the flavin semiquinone is formed. However the temperature dependencies of chemical shifts and linewidths reveal dynamics affecting loops close to the flavin, and regions that bind to partners in a variety of systems. These coincide with patterns of amino acid type conservation but not retention of specific residues, arguing against detailed specificity with respect to partners. We propose that the loops surrounding the flavin adopt altered conformations upon binding to partners and may even participate actively in electron transfer.

Conformational dependence of chemical shifts in the proline rich region of TAU protein.

Nuclear magnetic resonance (NMR) is an important method for structure elucidation of proteins, as it is an easily accessible and well understood method. To characterize intrinsically disordered proteins (IDPs) using computational models it is often necessary to analyze and integrate calculated observables with measurements derived from solution NMR experiments. In this case study, we investigate whether and which chemical shifts of the proline-rich region of Tau protein (residues 210-240) offer information about the conformational state to distinguish two different microscopic conformers. Using multiple computational methods, the chemical shifts of these two conformationally distinct structures are calculated. The different methods are compared regarding their ability to compute chemical shifts that are sensitive to conformational change. The analysis of the data shows significant differences between the available methods and gives suggestions for an improved pathway for ensemble reweighting. Nevertheless, the variation in the chemical shifts which are predicted for configurations that are commonly considered to belong to the same conformation is such that this obscures a comparison between distinct conformations. Conformational sensitivity is found for up to ∼26% of calculated chemical shifts. It is found to be unrelated to the atom element and has a minor relationship with the change in the corresponding ϕ dihedral angle.

Solution structure and pressure response of thioredoxin-1 of Plasmodium falciparum.

We present here the solution structures of the protein thioredoxin-1 from Plasmodium falciparum (PfTrx-1), in its reduced and oxidized forms. They were determined by high-resolution NMR spectroscopy at 293 K on uniformly 13C-, 15N-enriched, matched samples allowing to identification of even small structural differences. PfTrx-1 shows an α/β-fold with a mixed five-stranded β-sheet that is sandwiched between 4 helices in a β1 α1 β2 α2 β3 α3 β4 β5 α4 topology. The redox process of the CGPC motif leads to significant structural changes accompanied by larger chemical shift changes from residue Phe25 to Ile36, Thr70 to Thr74, and Leu88 to Asn91. By high-field high-pressure NMR spectroscopy, rare conformational states can be identified that potentially are functionally important and can be used for targeted drug development. We performed these experiments in the pressure range from 0.1 MPa to 200 MPa. The mean combined, random-coil corrected B1* values of reduced and oxidized thioredoxin are quite similar with -0.145 and -0.114 ppm GPa-1, respectively. The mean combined, random-coil corrected B2* values in the reduced and oxidized form are 0.179 and 0.119 ppm GPa-2, respectively. The mean ratios of the pressure coefficients B2/B1 are -0.484 and -0.831 GPa-1 in the reduced and oxidized form respectively. They differ at some points in the structure after the formation of the disulfide bond between C30 and C33. The thermodynamical description of the pressure dependence of chemical shifts requires the assumption of at least three coexisting conformational states of PfTrx-1. These three conformational states were identified in the reduced as well as in the oxidized form of the protein, therefore, they represent sub-states of the two main oxidation states of PfTrx-1.

Revisiting the influence of pH on 1JCαH and chemical shifts of glycine and alanine short oligopeptides.

The pH dependence of several NMR parameters of glycine and alanine short oligopeptides has been reported previously in different studies. Here we have thoroughly examined, summarized and demonstrated the dependences of 1H, 13C and 15N chemical shifts and protonation states of amino acids using two-dimensional NMR experiments. Nevertheless, 1JCαH one bond spin-spin coupling constants are more informative and convenient for determination of the position and protonation state of glycine and alanine residue in the oligopeptide chain. In particular, for various oligopeptides (up to six residues), it was shown that the pH dependence of 1JCαH of N-terminal glycine and alanine residues is larger than that of C-terminal groups, and in backbone residues, it is not influenced by pH and only slightly depends on the position of the amino acid residue in the chain.

Nuclear magnetic resonance study of the temperature dependence of paramagnetic chemical shifts of [Co(EDTA)]2− complexes in gelatin gel

Nuclear magnetic resonance study of the temperature dependence of paramagnetic chemical shifts of [Co(EDTA)]2− complexes in gelatin gel

(Invited) Unravelling Water-Ion Dynamics in Reverse Osmosis Membranes with Nuclear Magnetic Resonance Spectroscopy

Fundamental understanding of the charge (ions and water) transport in polymeric membranes used at the forefront of the water-energy nexus challenge is yet uncertain and depends on the complex interplay between polymer structure and dynamics that facilitate transport. Herein, we investigated the dynamics-transport of proton and ion transport in a rather neutrally charged organic membrane (i.e., polyamide) using solid-state NMR spectroscopy. Specifically, the role of competing ions' effect in complex ionic mixtures at the membrane interface has been explored on a molecular level. Proton and sodium ion diffusion measurements are made using pulsed-field gradient NMR diffusometry. The energy barriers for proton and ion transport within the active layer of the reverse osmosis (RO) membrane are assessed using magic angle spinning (MAS) and static NMR spectral line shape analysis. We have investigated the dynamics-transport of water and sodium ions in complex ionic mixtures of polyamide polymeric media using solid-state NMR spectroscopy. Through monitoring 13C, 23Na, and 1H NMR nuclei, quantitative insights into the diffusion of water (1H), sodium mobile ion (Na+), and polymer membrane dynamics (13C) are extrapolated. Furthermore, the spin-lattice (T1) relaxation time of sodium and water ions is investigated to obtain quantitative insight into how sodium and water ions’ rotational movements occur in the absence and presence of other competing seawater cations such as potassium. Room temperature spectra and spin-lattice relaxation times indicated the presence of both mobile and rigidly held ionic species in the membrane at different levels of relative humidity. The concentration and temperature dependence of relaxation times and chemical shifts have been investigated. NMR relaxation measurements detect how the water rotation is modified by sodium and potassium cations in the membrane. Results show that at low relative humidity and in the presence of competing ions, there are sodium ion resonances for crystalline sodium ions and rigidly held sodium ions on the surface. With increasing relative humidity and decreasing competing ions, the resonance suggests solution-like dynamic rotational movements of sodium ions in polyamide. The results confirm the change in activation energy barrier for sodium and hydrogen ion permeation in polyamide upon the presence of potassium ions.

Disorder in the Human Skp1 Structure is the Key to its Adaptability to Bind Many Different Proteins in the SCF Complex Assembly

Skp1(S-phase kinase-associated protein 1 - Homo sapiens) is an adapter protein of the SCF(Skp1-Cullin1-Fbox) complex, which links the constant components (Cul1-RBX) and the variable receptor (F-box proteins) in Ubiquitin E3 ligase. It is intriguing how Skp1 can recognise and bind to a variety of structurally different F-box proteins. For practical reasons, previous efforts have used truncated Skp1, and thus it has not been possible to track the crucial aspects of the substrate recognition process. In this background, we report the solution structure of the full-length Skp1 protein determined by NMR spectroscopy for the first time and investigate the sequence-dependent dynamics in the protein. The solution structure reveals that Skp1 has an architecture: β1-β2-H1-H2-L1–H3-L2-H4-H5-H6-H7(partially formed) and a long tail-like disordered C-terminus. Structural analysis using DALI (Distance Matrix Alignment) reveals conserved domain structure across species for Skp1. Backbone dynamics investigated using NMR relaxation suggest substantial variation in the motional timescales along the length of the protein. The loops and the C-terminal residues are highly flexible, and the (R2/R1) data suggests μs-ms timescale motions in the helices as well. Further, the dependence of amide proton chemical shift on temperature and curved profiles of their residuals indicate that the residues undergo transitions between native state and excited state. The curved profiles for several residues across the length of the protein suggest that there are native-like low-lying excited states, particularly for several C-terminal residues. Our results provide a rationale for how the protein can adapt itself, bind, and get functionally associated with other proteins in the SCF complex by utilising its flexibility and conformational sub-states.

Negative thermal expansion of a disordered native protein

Despite immense interest in thermal expansion of solid materials, negative thermal expansion in particular, expansivity of proteins near ambient temperature is minimally reported. One reason for the paucity of protein expansion studies could be the susceptibility of proteins to conformational changes often within subdenaturing temperatures, given that the expansivity phenomenon should include only vibrational fluctuations in atom positions in the absence of a conformational change. This study encounters a disordered plant protein called At PP16-1 ( Arabidopsis thaliana phloem protein type 16-1) which shows negative thermal expansion in the 292–309(±1) K range of temperature at no expense of conformational transition. Temperature dependence of NMR chemical shifts of backbone atoms, global tumbling time derived from 15 N relaxations, and volume compressibility measurements yield a negative linear expansion coefficient 〈α〉 ∼ −5.3 × 10 −3 K −1 averaged over a sizable set of hydrogen bonds, and a decrease in the root mean square volume fluctuation by ∼36%. A frequency spectrum of normal modes in which one or a fewer low frequency vibrational modes of large fluctuation amplitudes are excited at the lower end, and many high-frequency vibrational modes of lower fluctuation amplitudes are excited at the higher end of the temperature range can explain negative thermal expansion.

Quantitative NMR analysis of the kinetics of prenucleation oligomerization and aggregation of pathogenic huntingtin exon-1 protein

The N-terminal region of the huntingtin protein, encoded by exon-1 (httex1) and containing an expanded polyglutamine tract, forms fibrils that accumulate in neuronal inclusion bodies, resulting in Huntington's disease. We previously showed that reversible formation of a sparsely populated tetramer of the N-terminal amphiphilic domain, comprising a dimer of dimers in a four-helix bundle configuration, occurs on the microsecond timescale and is an essential prerequisite for subsequent nucleation and fibril formation that takes place orders of magnitude slower on a timescale of hours. For pathogenic httex1, such as httex1Q35 with 35 glutamines, NMR signals decay too rapidly to permit measurement of time-intensive exchange-based experiments. Here, we show that quantitative analysis of both the kinetics and mechanism of prenucleation tetramerization and aggregation can be obtained simultaneously from a series of 1H-15N band-selective optimized flip-angle short-transient heteronuclear multiple quantum coherence (SOFAST-HMQC) correlation spectra. The equilibria and kinetics of tetramerization are derived from the time dependence of the 15N chemical shifts and 1H-15N cross-peak volume/intensity ratios, while the kinetics of irreversible fibril formation are afforded by the decay curves of 1H-15N cross-peak intensities and volumes. Analysis of data on httex1Q35 over a series of concentrations ranging from 200 to 750 μM and containing variable (7 to 20%) amounts of the Met7O sulfoxide species, which does not tetramerize, shows that aggregation of native httex1Q35 proceeds via fourth-order primary nucleation, consistent with the critical role of prenucleation tetramerization, coupled with first-order secondary nucleation. The Met7O sulfoxide species does not nucleate but is still incorporated into fibrils by elongation.

A fine balance of hydrophobic-electrostatic communication pathways in a pH-switching protein

Allostery is the phenomenon of coupling between distal binding sites in a protein. Such coupling is at the crux of protein function and regulation in a myriad of scenarios, yet determining the molecular mechanisms of coupling networks in proteins remains a major challenge. Here, we report mechanisms governing pH-dependent myristoyl switching in monomeric hisactophilin, whereby the myristoyl moves between a sequestered state, i.e., buried within the core of the protein, to an accessible state, in which the myristoyl has increased accessibility for membrane binding. Measurements of the pH and temperature dependence of amide chemical shifts reveal protein local structural stability and conformational heterogeneity that accompany switching. An analysis of these measurements using a thermodynamic cycle framework shows that myristoyl-proton coupling at the single-residue level exists in a fine balance and extends throughout the protein. Strikingly, small changes in the stereochemistry or size of core and surface hydrophobic residues by point mutations readily break, restore, or tune myristoyl switch energetics. Synthesizing the experimental results with those of molecular dynamics simulations illuminates atomistic details of coupling throughout the protein, featuring a large network of hydrophobic interactions that work in concert with key electrostatic interactions. The simulations were critical for discerning which of the many ionizable residues in hisactophilin are important for switching and identifying the contributions of nonnative interactions in switching. The strategy of using temperature-dependent NMR presented here offers a powerful, widely applicable way to elucidate the molecular mechanisms of allostery in proteins at high resolution.

Simultaneous Estimation of Two Coupled Hydrogen Bond Geometries from Pairs of Entangled NMR Parameters: The Test Case of 4-Hydroxypyridine Anion.

The computational method for estimating the geometry of two coupled hydrogen bonds with geometries close to linear using a pair of spectral NMR parameters was proposed. The method was developed based on the quantum-chemical investigation of 61 complexes with two hydrogen bonds formed by oxygen and nitrogen atoms of the 4-hydroxypyridine anion with OH groups of substituted methanols. The main idea of the method is as follows: from the NMR chemical shifts of nuclei of atoms forming the 4-hydroxylpyridine anion, we select such pairs, whose values can be used for simultaneous determination of the geometry of two hydrogen bonds, despite the fact that every NMR parameter is sensitive to the geometry of each of the hydrogen bonds. For these parameters, two-dimensional maps of dependencies of NMR chemical shifts on interatomic distances in two hydrogen bonds were constructed. It is shown that, in addition to chemical shifts of the nitrogen atom and quaternary carbon, which are experimentally difficult to obtain, chemical shifts of the carbons and protons of the CH groups can be used. The performance of the proposed method was evaluated computationally as well on three additional complexes with substituted alcohols. It was found that, for all considered cases, hydrogen bond geometries estimated using two-dimensional correlations differed from those directly calculated by quantum-chemical methods by not more than 0.04 Å.

EF-hand protein, EfhP, specifically binds Ca2+ and mediates Ca2+ regulation of virulence in a human pathogen Pseudomonas aeruginosa

Calcium (Ca2+) is well known as a second messenger in eukaryotes, where Ca2+ signaling controls life-sustaining cellular processes. Although bacteria produce the components required for Ca2+ signaling, little is known about the mechanisms of bacterial Ca2+ signaling. Previously, we have identified a putative Ca2+-binding protein EfhP (PA4107) with two canonical EF-hand motifs and reported that EfhP mediates Ca2+ regulation of virulence factors production and infectivity in Pseudomonas aeruginosa, a human pathogen causing life-threatening infections. Here, we show that EfhP selectively binds Ca2+ with 13.7 µM affinity, and that mutations at the +X and −Z positions within each or both EF-hand motifs abolished Ca2+ binding. We also show that the hydrophobicity of EfhP increased in a Ca2+-dependent manner, however no such response was detected in the mutated proteins. 15 N-NMR showed Ca2+-dependent chemical shifts in EfhP confirming Ca2+-binding triggered structural rearrangements in the protein. Deletion of efhP impaired P. aeruginosa survival in macrophages and virulence in vivo. Disabling EfhP Ca2+ binding abolished Ca2+ induction of pyocyanin production in vitro. These data confirm that EfhP selectively binds Ca2+, which triggers its structural changes required for the Ca2+ regulation of P. aeruginosa virulence, thus establishing the role of EfhP as a Ca2+ sensor.

Nuclear magnetic resonance thermosensing properties of holmium(III) and thulium(III) tris(tetra-15-crown-5-phthalocyaninato) complexes

Temperature dependences of paramagnetic chemical shifts in NMR spectra of lanthanide tris-phthalocyaninates Ln2[(15C5)4Pc]3(where [(15C5)4Pc][Formula: see text] is 2,3,9,10,16,17,24,25-tetrakis(15-crown-5)phthalocyaninate dianion, Ln = Ho(III), Tm(III)) have been studied in the physiological temperature range (from 303 to 323 K). The observed maximum temperature sensitivity [Formula: see text]/dT turns out to be 0.25 ppm/K for the signals of the thulium complex and 0.16 ppm/K for the holmium complex. By the example of Tm2[(15C5)4Pc]3, it has been shown that the use of temperature sensitivities normalized to signal half-widths (∣CT∣/[Formula: see text] is expedient to judge the applicability of the observed temperature dependences of LISs of analogous lanthanide complexes (Ln = Tb, Dy, Ho, Tm) for determining temperatures. The investigated kinetically and thermodynamically stable Ln2[(15C5)4Pc]3complexes can be considered promising for the design of thermosensitive NMR probes for determination of the local temperature in nonpolar solutions.

Holmium complex with phospholipids as 1H NMR temperature probe for membrane systems.

The temperature dependence of the lanthanide-induced chemical shifts (LISs) was studied for the systems containing 1-palmitoyl-2-oleoylphosphatidylcholine (POPC)-Ho, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)-Ho and 1,2-dimyristoyl-sn-glycero-3-phosphorylcholine (DMPC)-Ho in unilamellar liposomes. In the POPC-Ho system, anti-Curie dependence of LISs is observed, same as previously observed in POPC-Pr system. In the DPPC- and DMPC-Ho systems, temperature features are observed which are probably connected with phase transition.