Solid-state Nuclear Magnetic Resonance Techniques Research Articles

Characterization of Amyloid Structures at the Molecular Level by Solid State Nuclear Magnetic Resonance Spectroscopy

Solid state nuclear magnetic resonance (NMR) spectroscopy is particularly useful in structural studies of amyloid fibrils because solid state NMR techniques have unique capabilities as site-specific, molecular-level structural probes of noncrystalline materials. These techniques provide experimental data that strongly constrain the secondary, tertiary, and quaternary structures of amyloid fibrils, permitting the development of experimentally based structural models. Examples of techniques that are applicable to amyloid samples prepared with isotopic labeling of specific sites and to samples prepared with uniform isotopic labeling of selected residues are presented, illustrating the utility of the various techniques and labeling schemes. Information regarding the preparation of amyloid samples for solid state NMR measurements is also included.

Molecular Properties of Ibuprofen and Its Solid Dispersions with Eudragit RL100 Studied by Solid-State Nuclear Magnetic Resonance

The aim of this study was to investigate, at a molecular level, the structural and dynamic properties of the acidic and sodium salt forms of ibuprofen and their solid dispersions with Eudragit RL100, obtained by two different preparation methods (physical mixtures and co-evaporates), which may affect the release properties of these drugs in their dispersed forms. (1)H and (13)C high-resolution solid-state nuclear magnetic resonance techniques, including single-pulse excitation magic-angle spinning, cross-polarization magic-angle spinning, and other selective 1D spectra, as well as more advanced 2D techniques Frequency Switched Lee-Goldburg HETeronuclear CORrelation (FSLG-HETCOR) and Magic Angle Spinning -J- Heteronuclear Multiple-Quantum Coherence (MAS-J-HMQC) and relaxation time measurements were used. A full assignment of (13)C resonances and precise (1)H chemical shift values were achieved for the first time for the two forms of ibuprofen that showed very different inter-conformational dynamic behavior; drug-polymer interactions were observed and characterized in the co-evaporates of the two forms but were much stronger for the acidic form. A combined analysis of several high-resolution solid-state nuclear magnetic resonance experiments allowed the investigation of the structural and dynamic properties of the pure drugs and of the solid dispersions with the polymer, as well as of the degree of mixing between drug and polymer and of the chemical nature of their interaction. Such information could be related to the in vitro drug release profiles observed for the tested co-evaporates.

Parallel beta-sheets and polar zippers in amyloid fibrils formed by residues 10-39 of the yeast prion protein Ure2p.

We report the results of solid-state nuclear magnetic resonance (NMR) and atomic force microscopy measurements on amyloid fibrils formed by residues 10-39 of the yeast prion protein Ure2p (Ure2p(10)(-)(39)). Measurements of intermolecular (13)C-(13)C nuclear magnetic dipole-dipole couplings indicate that Ure2p(10)(-)(39) fibrils contain in-register parallel beta-sheets. Measurements of intermolecular (15)N-(13)C dipole-dipole couplings, using a new solid-state NMR technique called DSQ-REDOR, are consistent with hydrogen bonds between side chain amide groups of Gln18 residues. Such side chain hydrogen bonding interactions have been called "polar zippers" by M. F. Perutz and have been proposed to stabilize amyloid fibrils formed by peptides with glutamine- and asparagine-rich sequences, such as Ure2p(10)(-)(39). We propose that polar zipper interactions account for the in-register parallel beta-sheet structure in Ure2p(10)(-)(39) fibrils and that similar peptides will also exhibit parallel beta-sheet structures in amyloid fibrils. We present molecular models for Ure2p(10)(-)(39) fibrils that are consistent with available experimental data. Finally, we show that solid-state (13)C NMR chemical shifts for (13)C-labeled Ure2p(10)(-)(39) fibrils are insensitive to hydration level, indicating that the fibril structure is not affected by the presence or absence of bulk water.

A New Way to Use Solid‐State Carbon‐13 Nuclear Magnetic Resonance Spectroscopy to Study the Sorption of Organic Compounds to Soil Organic Matter

Several solid-state 13C nuclear magnetic resonance (NMR) techniques were used to characterize soil organic matter spiked with 13C-labeled organic compounds spanning a range of hydrophobicities (benzoic acid, benzophenone, naphthalene, phenanthrene, and palmitic acid). The chemical shifts of NMR resonances of the sorbed species were shifted by up to 3 ppm relative to those of the neat compounds. Sorption also resulted in increased resonance linewidth for the compounds containing a single 13C label, indicating the presence of a range of different chemical environments at the sites of sorption. On the other hand, sorption decreased the linewidth of the resonance of naphthalene, which was uniformly 13C-labeled. This was attributed to the removal of intermolecular 13C-13C dipolar coupling. Heterogeneity of the organic matter was demonstrated using the spectral editing technique proton spin relaxation editing (PSRE), which enabled the identification and quantification of charcoal-rich domains characterized by rapid rates of proton spin-lattice relaxation in the static frame (T1H), and humic domains characterized by slow rates of T1H relaxation. Furthermore it was demonstrated that the sorbed 13C-labeled molecules "inherit" the T1H "signature" of the organic matrix in their immediate vicinity. Thus PSRE on the spiked soils enabled evaluation of the relative affinity of the two domain types for the sorbate molecules. The charcoal-rich domains were shown to have a twofold to tenfold greater affinity for the organic compounds, with greater differences found for the more hydrophobic compounds.

Order parameters of unsaturated phospholipids in membranes and the effect of cholesterol: a 1H–13C solid-state NMR study at natural abundance

Most biological phospholipids contain at least one unsaturated alkyl chain. However, few order parameters of unsaturated lipids have been determined because of the difficulty associated with isotopic labeling of a double bond. Dipolar recoupling on axis with scaling and shape preservation (DROSS) is a solid-state nuclear magnetic resonance technique optimized for measuring (1)H-(13)C dipolar couplings and order parameters in lipid membranes in the fluid phase. It has been used to determine the order profile of 1,2-dimyristoyl-sn-glycero-3-phosphocholine hydrated membranes. Here, we show an application for the measurement of local order parameters in multilamellar vesicles containing unsaturated lipids. Taking advantage of the very good (13)C chemical shift dispersion, one can easily follow the segmental order along the acyl chains and, particularly, around the double bonds where we have been able to determine the previously misassigned order parameters of each acyl chain of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). We have followed the variation of such order profiles with temperature, unsaturation content and cholesterol addition. We have found that the phase formed by DOPC with 30% cholesterol is analogous to the liquid-ordered (l(o)) phase. Because these experiments do not require isotopic enrichment, this technique can, in principle, be applied to natural lipids and biomembranes.

Dynamics of Collagen in Articular Cartilage Studied by Solid‐State NMR Methods

AbstractFor Abstract see ChemInform Abstract in Full Text.

Highly Ordered Interstitial Water Observed in Bone by Nuclear Magnetic Resonance

NMR was used to study the nanostructure of bone tissue. Distance measurements show that the first water layer at the surface of the mineral in cortical bone is structured. This water may serve to couple the mineral to the organic matrix and may play a role in deformation. The unique mechanical characteristics of bone tissue have not yet been satisfactorily connected to the exact molecular architecture of this complex composite material. Recently developed solid-state nuclear magnetic resonance (NMR) techniques are applied here to the mineral component to provide new structural distance constraints at the subnanometer scale. NMR dipolar couplings between structural protons (OH(-) and H(2)O) and phosphorus (PO(4)) or carbon (CO(3)) were measured using the 2D Lee-Goldburg Cross-Polarization under Magic-Angle Spinning (2D LG-CPMAS) pulse sequence, which simultaneously suppresses the much stronger proton-proton dipolar interactions. The NMR dipolar couplings measured provide accurate distances between atoms, e.g., OH and PO(4) in apatites. Excised and powdered femoral cortical bone was used for these experiments. Synthetic carbonate ( approximately 2-4 wt%)-substituted hydroxyapatite was also studied for structural comparison. In synthetic apatite, the hydroxide ions are strongly hydrogen bonded to adjacent carbonate or phosphate ions, with hydrogen bond (O-H) distances of approximately 1.96 A observed. The bone tissue sample, in contrast, shows little evidence of ordered hydroxide. Instead, a very ordered (structural) layer of water molecules is identified, which hydrates the small bioapatite crystallites through very close arrangements. Water protons are approximately 2.3-2.55 A from surface phosphorus atoms. In synthetic carbonated apatite, strong hydrogen bonds were observed between the hydroxide ions and structural phosphate and carbonate units in the apatite crystal lattice. These hydrogen bonding interactions may contribute to the long-range stability of this mineral structure. The biological apatite in cortical bone tissue shows evidence of hydrogen bonding with an ordered surface water layer at the faces of the mineral particles. This structural water layer has been inferred, but direct spectroscopic evidence of this interstitial water is given here. An ordered structural water layer sandwiched between the mineral and the organic collagen fibers may affect the biomechanical properties of this complex composite material.

NMR analysis of plant nitrogen metabolism

The analysis of primary and secondary nitrogen metabolism in plants by nuclear magnetic resonance (NMR) spectroscopy is comprehensively reviewed. NMR is a versatile analytical tool, and the combined use of (1)H, (2)H, (13)C, (14)N and (15)N NMR allows detailed investigation of the acquisition, assimilation and metabolism of nitrogen. The analysis of tissue extracts can be complemented by the in vivo NMR analysis of functioning tissues and cell suspensions, and by the application of solid state NMR techniques. Moreover stable isotope labelling with (2)H-, (13)C- and (15)N-labelled precursors provides direct insight into specific pathways, with the option of both time-course and steady state analysis increasing the potential value of the approach. The scope of the NMR method, and its contribution to studies of plant nitrogen metabolism, are illustrated with a wide range of examples. These include studies of the GS/GOGAT pathway of ammonium assimilation, investigations of the metabolism of glutamate, glycine and other amino acids, and applications to tropane alkaloid metabolism. The continuing development of the NMR technique, together with potential applications in the emerging fields of metabolomics and metabolic flux analysis, leads to the conclusion that NMR will play an increasingly valuable role in the analysis of plant nitrogen metabolism.

Functionalized nanoporous silicas for the immobilization of penicillin acylase

Nanoporous silica materials with uniform pore size and ordered structure have drawn growing interest of researchers since 1990s. A large-pore nanoporous material, SBA-15, was functionalized with organosilanes by co-condensation method in the presence of nonionic triblock copolymer P123 as a template under acidic conditions. The functionalization was demonstrated by using five organosilanes, namely 3-aminopropyltriethoxysilane (APTES), 3-mercaptopropyltrimethoxysilane (MPTMS), phenyltrimethoxysilane (PTMS), vinyltriethoxysilane (VTES), and 4-(triethoxysilyl)butyronitrile (TSBN), which modified the surface properties of the silica materials, enabling the materials to be a promising support for immobilization of biological molecules. The functionalized SBA-15 materials exhibited long-range ordering of two-dimensional hexagonal pore arrays of size ranging from 66 to 90 Å as demonstrated by small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and physical adsorption techniques. A variety of organosilane density in the range of 0.5–2.6 mmol/g was achieved as revealed by elemental analysis and solid-state nuclear magnetic resonance (NMR) techniques. The functionalized materials displayed improved properties for immobilization of penicillin acylase (PA) in comparison with pure-silica SBA-15. Such improvement is believed to be due to the enhanced surface hydrophobicity and electrostatic interactions of the functional groups with the enzyme.

Functionalized nanoporous silicas for the immobilization of penicillin acylase

Nanoporous silica materials with uniform pore size and ordered structure have drawn growing interest of researchers since 1990s. A large-pore nanoporous material, SBA-15, was functionalized with organosilanes by co-condensation method in the presence of nonionic triblock copolymer P123 as a template under acidic conditions. The functionalization was demonstrated by using five organosilanes, namely 3-aminopropyltriethoxysilane (APTES), 3-mercaptopropyltrimethoxysilane (MPTMS), phenyltrimethoxysilane (PTMS), vinyltriethoxysilane (VTES), and 4-(triethoxysilyl)butyronitrile (TSBN), which modified the surface properties of the silica materials, enabling the materials to be a promising support for immobilization of biological molecules. The functionalized SBA-15 materials exhibited long-range ordering of two-dimensional hexagonal pore arrays of size ranging from 66 to 90Å as demonstrated by small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and physical adsorption techniques. A variety of organosilane density in the range of 0.5–2.6mmol/g was achieved as revealed by elemental analysis and solid-state nuclear magnetic resonance (NMR) techniques. The functionalized materials displayed improved properties for immobilization of penicillin acylase (PA) in comparison with pure-silica SBA-15. Such improvement is believed to be due to the enhanced surface hydrophobicity and electrostatic interactions of the functional groups with the enzyme.

13C NMR Molecular dynamic investigation of tropical wood Angelin Pedra ( Hymenolobium paetrum)

Time has shown wood as a very important material in several areas related to civil construction. Because of its organic origin, wood presents different physical and mechanical properties for different species. In consequence of these variations, there is the necessity to study chemical composition and molecular dynamic to better understand its property that will promote the use in civil construction. The focus of this work is to evaluate the Angelin Pedra wood in relation to the main chemical components, the domain type and the chemical components that constitute these domains. Solid state nuclear magnetic resonance (NMR) will be used for that, since the main advantage of NMR comparing to other techniques specially for the sample in question, is the potential of this spectroscopy to provide analysis of all functional group without pre-treatment of the sample. Some solid state NMR techniques were used and it was observed that the wood in investigation presents different packing, cells arrangements and chains ordination along the fibers in the different parts of the wood, because of the different distribution of the main wood components along the fibers.

Dynamics of collagen in articular cartilage studied by solid-state NMR methods.

Methods for studying the fast molecular dynamics of the rigid macromolecules in cartilage are described. The strong dipolar couplings and chemical shift anisotropies of these molecules necessitate application of solid-state nuclear magnetic resonance (NMR) techniques such as magic-angle spinning, cross-polarization, and high-power dipolar decoupling to obtain resolved NMR spectra. The molecules in cartilage that are amenable to these techniques are collagen and the rigid portion of the glycosaminoglycans (mostly hyaluronan). Site-specific mobility information is obtained from scaled dipolar couplings measured in 2D NMR experiments. Motionally averaged dipolar couplings can be interpreted in terms of order parameters that provide information about the amplitudes of molecular motions. Qualitative dynamics information is obtained from the simple wideline separation experiment measuring 1H-1H widelines representing the strength of the 1H-1H dipolar coupling. Quantitative values for molecular order parameters are obtained from precise measurements of 1H-13C dipolar couplings along the C-H bond vector. Two experimental techniques, the Lee-Goldburg cross-polarization and the dipolar coupling/chemical shift experiment, are illustrated to measure these 1H-13C dipolar couplings. Unlike glycosaminoglycans in cartilage, the collagen moiety remains substantially ordered, undergoing fast small amplitude motions. As enzymes cleave the macromolecules in articular cartilage in the course of arthritis, solid-state NMR techniques are capable of characterizing the increased motions of their degradation products in diseased cartilage.

Solid-state NMR spectroscopy method for determination of the backbone torsion angle psi in peptides with isolated uniformly labeled residues.

We demonstrate a solid-state nuclear magnetic resonance technique, with the acronym ROCSA-LG, for the determination of backbone torsion angles psi in peptides with multiple, but isolated, uniformly labeled residues. The method correlates the 13C' chemical shift anisotropy and the 13Calpha-1Halpha heteronuclear dipolar tensors within a single uniformly labeled residue in a two-dimensional (2D) experiment. The technique requires the measurement of only five 2D spectra and is compatible with high-speed magic-angle spinning. Experimental results are presented for the 17-residue alpha-helical peptide MB(i+4)EK and for amyloid fibrils formed by the 15-residue peptide Abeta11-25.

Dynamic structure of pharaonis phoborhodopsin (sensory rhodopsin II) and complex with a cognate truncated transducer as revealed by site-directed 13C solid-state NMR

We have recorded 13C nuclear magnetic resonance (NMR) spectra of [3- 13C]Ala, [1- 13C]Val-labeled pharaonis phoborhodopsin ( ppR or sensory rhodopsin II) incorporated into egg PC (phosphatidylcholine) bilayer, by means of site-directed high-resolution solid-state NMR techniques. Seven 13C NMR signals from transmembrane α-helices were resolved for [3- 13C]Ala- ppR at almost the same positions as those of bacteriorhodopsin (bR), except for the suppressed peaks in the loop regions in spite of the presence of at least three Ala residues. In contrast, 13C NMR signals from the loops were visible from [1- 13C]Val- ppR but their peak positions of the transmembrane α-helices are not always the same between ppR and bR. The motional frequency of the loop regions in ppR was estimated as 10 5 Hz in view of the suppressed peaks from [3- 13C]Ala- ppR due to interference with proton decoupling frequency. We found that conformation and dynamics of ppR were appreciably altered by complex formation with a cognate truncated transducer pHtr II (1–159). In particular, the C-terminal α-helix protruding from the membrane surface is involved in the complex formation and subsequent fluctuation frequency is reduced by one order of magnitude.

The evaluation of different MAS techniques at low spinning rates in aqueous samples and in the presence of magnetic susceptibility gradients

It was recently demonstrated that the nuclear magnetic resonance (NMR) linewidths for stationary biological samples are dictated mainly by magnetic susceptibility gradients, and that phase-altered spinning sideband (PASS) and phase-corrected magic angle turning (PHORMAT) solid-state NMR techniques employing slow and ultra-slow magic angle spinning (MAS) frequencies can be used to overcome the static susceptibility broadening to yield high-resolution, spinning sideband (SSB)-free 1H NMR spectra [Magn. Reson. Med. 46 (2001) 213; 47 (2002) 829]. An additional concern is that molecular diffusion in the presence of the susceptibility gradients may limit the minimum useful MAS frequency by broadening the lines and reducing SSB suppression at low spinning frequencies. In this article the performance of PASS, PHORMAT, total sideband suppression (TOSS), and standard MAS techniques were evaluated as a function of spinning frequency. To this end, 300 MHz (7.05 T) 1H NMR spectra were acquired via PASS, TOSS, PHORMAT, and standard MAS NMR techniques for a 230-μm-diameter spherical glass bead pack saturated with water. The resulting strong magnetic susceptibility gradients result in a static linewidth of about 3.7 kHz that is larger than observed for a natural biological sample, constituting a worst-case scenario for examination of susceptibility broadening effects. Results: (I) TOSS produces a distorted centerband and fails in suppressing the SSBs at a spinning rate below ∼1 kHz. (II) Standard MAS requires spinning speeds above a few hundred Hz to separate the centerband from the SSBs. (III) PASS produces nearly SSB-free spectra at spinning speeds as low as 30 Hz, and is only limited by T 2-induced signal losses. (IV) With PHORMAT, a SSB-free isotropic projection is obtained at any spinning rate, even at an ultra-slow spinning rate as slow as 1 Hz. (V) It is found empirically that the width of the isotropic peak is proportional to F − x , where F is the spinning frequency, and x=2 for MAS, 0.84 for PASS, and 0.5 for PHORMAT.

Domain mobility of humic acids investigated with one- and two-dimensional nuclear magnetic resonance: support for dual-mode sorption model

Dual-mode sorption model of soil organic matter (SOM) postulates that SOM consists of condensed and expanded domains; sorption of organic compounds including pesticides in the latter is linear and noncompetitive whereas sorption in the former is nonlinear and competitive between solutes. Although the model has been cited numerous times in the literature, spectroscopic data is needed to support the domain heterogeneity of SOM in terms of mobility difference. In this study several humic acid (HA) samples were investigated using one-dimensional proton wideline and two-dimensional WISE (wideline separation) solid-state nuclear magnetic resonance (NMR) techniques. One-dimensional proton wideline could only estimate the overall domain mobility of HA. The results from this technique showed a gradual mobility change (from rigid to mobile) of structural components of HA samples. Two-dimensional WISE experiments clearly indicated the mobility difference for different segments and even for the same functional groups. These results are consistent with the postulation of the dual-mode sorption model for SOM.

Solid‐State Carbon‐13 Nuclear Magnetic Resonance of Humic Acids at High Magnetic Field Strengths

Use of solid-state 13C nuclear magnetic resonance (NMR) spectroscopy has become commonplace in studies of humic substances in soils and sediments, but when modern high-field spectrometers are employed, care must be taken to ensure that the data obtained accurately reflect the chemical composition of these complex materials in environmental systems. In an effort to evaluate the quality of solid-state 13C NMR spectra obtained with modern high-field spectrometers, we conducted a series of experiments to examine spectra of various humic acids taken under a variety of conditions. We evaluate conditions for obtaining semiquantitative cross polarization magic angle spinning (CPMAS) 13C NMR spectra of humic acids at high magnetic field and spinning frequency. We examine the cross polarization (CP) dynamics under both traditional and ramp CP conditions on Cedar Creek humic acid. Fitted equilibrium intensities from these CP dynamic studies compare to within 3.4% of the intensities determined from a Bloch decay spectrum of the same sample. With a 1-ms contact time, ramp CP and traditional CP spectra were acquired on this sample and were found to compare to within 5.4% of the Bloch decay spectrum; however, the signal-to-noise ratio per hour of data acquisition was found to double under ramp CP conditions. These results demonstrate the power of applying modern solid-state NMR techniques at high magnetic field strengths. With these techniques, high-quality, semiquantitative spectra can be quickly produced, allowing the application of solid-state NMR techniques to more environmentally relevant samples, especially those where the quantity is limited.

Site-Directed Rotational Resonance Solid-State NMR Distance Measurements Probe Structure and Mechanism in the Transmembrane Domain of the Serine Bacterial Chemoreceptor

The serine receptor of bacterial chemotaxis is an ideal system in which to investigate the molecular mechanism of transmembrane signaling. Solid-state nuclear magnetic resonance (NMR) techniques such as rotational resonance provide a means for measuring local structure and ligand-induced structural changes in intact membrane proteins bound to native membrane vesicles. A general site-directed biosynthetic (13)C labeling strategy is used to direct the distance measurements to a specific site; the distance is measured between a unique Cys residue and a non-unique, low-abundance residue (Tyr or Phe). A (13)C-(13)C internuclear distance measurement from (13)CO(i) to (13)C beta(i + 3) at the periplasmic edge of the second membrane-spanning helix (TM2) of 5.1 +/- 0.2 A is consistent with the predicted alpha-helical structure and thus demonstrates an accurate long-distance rotational resonance measurement in the 120 kDa membrane-bound receptor. These measurements require a correction for the rotational resonance exchange between the multiple labels of the non-unique amino acid and the natural-abundance (13)C, which is critical to distance measurements in complex systems. A second (13)C-(13)C distance measurement between the transmembrane helices provides a high-resolution measurement of tertiary structure in the transmembrane region. The measured 5.0-5.3 A distance in the presence and absence of ligand is consistent with structural models for the transmembrane region and a proposed signaling mechanism in which ligand binding induces a 1.6 A translation of TM2. This approach can be used for additional measurements of the structure of the transmembrane region and to determine whether the ligand-induced motion is indeed propagated through the transmembrane helices.

Physical miscibility and chemical reactions between diglycidylether of bisphenol-A epoxy and poly(4-vinyl phenol)

Physical miscibility at ambient and chemical interactions at elevated temperatures between a difunctional epoxy of diglycidylether of bisphenol-A (DGEBA) and a linear phenylhydroxyl-containing polymer, poly(4-vinyl phenol) (PVPh), were investigated by differential scanning calorimetry, Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy, and solid-state 13C nuclear magnetic resonance (NMR). The DGEBA/PVPh mixture was proven to be homogeneous and miscible. At elevated temperatures, the epoxy/PVPh mixture developed a network-like homogeneous solid, which was a result of reactions between the epoxide of DGEBA epoxy and phenylhydroxyl of the linear PVPh polymer. By using FT-IR and solid-state 13C NMR techniques, mechanisms of reactions leading to a homogeneous network between the DGEBA epoxy resin and PVPh polymer have been probed.

Structural Investigation by Multinuclear Solid State NMR and X-ray Diffraction of As-Synthesized, Dehydrated, and Calcined AlPO4-SOD

AlPO4-SOD, a microporous aluminophosphate, was synthesized in a quasi-nonaqueous medium using dimethylformamide as solvent and template. The as-synthesized, dehydrated, calcined materials and the corresponding rehydrated phases were investigated by various solid-state nuclear magnetic resonance (NMR) and powder X-ray diffraction techniques. Structural data from the NMR study are in a very good agreement with the as-synthesized AlPO4-SOD structure refined from powder synchrotron data. 31P homonuclear correlation and 31P/27Al 3QHETCOR experiments allowed the complete assignment of 31P and 27Al resonances to the corresponding crystallographic sites. 31P and 27Al NMR spectra are drastically modified after dehydration at 200 °C and calcination at 800 °C. A possible structural rearrangement of the template molecules is proposed that explains NMR and XRD data of the dehydrated material. The structure of the calcined material solved by powder XRD is in agreement with the NMR data.