共查询到20条相似文献,搜索用时 31 毫秒
1.
Mutimura C. Gatarayiha Mark D. Laing Ray M. Miller 《Experimental & applied acarology》2010,50(3):217-229
Greenhouse experiments were conducted on various crops (cucumber, tomato, eggplant, green bean) to ascertain the effects of Break-thru® (polyether-polymethylsiloxane-copolymer, a silicone surfactant) and an oil emulsion, on Beauveria bassiana (Balsamo) Vuillemin (Bb) applications for the control of the two spotted spider mite, Tetranychus urticae Koch. The objectives were to compare a) the efficacy of Bb control when applied in aqueous Break-thru® or an oil emulsion; b) the effects of various concentrations of Bb conidia, as affected by each surfactant; and c) the effects of Break-thru® on the activity of the fungus. Conidia were suspended either in an aqueous Break-thru® or an emulsifiable formulation at different conidial concentrations (1.05 × 106, 2.1 × 106 and 4.2 × 106 conidia ml?1) and sprayed onto leaves 2 weeks after artificial pest inoculation. Two sprays were performed, with an interval of one week from one spray to another, and T. urticae population counts (both motile and egg stages) were made on plant leaves 7 days after each spray. Bb conidia in Break-thru® were more efficacious than conidia in emulsifiable formulation. With the highest rate of conidia (4.2 × 106 conidia ml?1), mortality of adult mites ranged from 60 ± 4.2 (mean ± SE) to 85.7 ± 4.3% in the Break-thru® suspension and 39.4 ± 7 to 61.3 ± 6% in the oil emulsion. Leaf damage index was also substantially reduced from 70% in the unsprayed control to 40% by the application of Bb conidia at the highest rate with Break-thru®. Break-thru® can be combined with Bb in the integrated management of T. urticae and Isolate R444 is a promising candidate for the control of the pest. 相似文献
2.
Magda R. A. Ferreira Rosilene R. Santiago Tatiane P. de Souza Eryvaldo S. T. Egito Elquio E. Oliveira Luiz A. L. Soares 《AAPS PharmSciTech》2010,11(3):1383-1390
Carapa guianensis, a popular medicinal plant known as “Andiroba” in Brazil, has been used in traditional medicine as an insect repellent and anti-inflammatory product. Additionally, this seed oil has been reported in the literature as a repellent against Aedes aegypti. The aim of this work is to report on the emulsification of vegetable oils such as “Andiroba” oil by using a blend of nonionic surfactants (Span 80® and Tween 20®), using the critical hydrophilic–lipophilic balance (HLB) and pseudo-ternary diagram as tools to evaluate the system’s stability. The emulsions were prepared by the inverse phase method. Several formulations were made according to a HLB spreadsheet design (from 4.3 to 16.7), and the products were stored at 25°C and 4°C. The emulsion stabilities were tested both long- and short-term, and the more stable one was used for the pseudo-ternary diagram study. The emulsions were successfully obtained by a couple of surfactants, and the HLB analysis showed that the required HLB of the oil was 16.7. To conclude, the pseudo-ternary diagram identified several characteristic regions such as emulsion, micro-emulsion, and separation of phases. 相似文献
3.
M. Naiserová K. Kubová J. Vysloužil S. Pavloková D. Vetchý M. Urbanová J. Brus J. Vysloužil P. Kulich 《AAPS PharmSciTech》2018,19(2):681-692
Burst drug release is often considered a negative phenomenon resulting in unexpected toxicity or tissue irritation. Optimal release of a highly soluble active pharmaceutical ingredient (API) from hypromellose (HPMC) matrices is technologically impossible; therefore, a combination of polymers is required for burst effect reduction. Promising variant could be seen in combination of HPMC and insoluble Eudragits® as water dispersions. These can be applied only on API/insoluble filler mixture as over-wetting prevention. The main hurdle is a limited water absorption capacity (WAC) of filler. Therefore, the object of this study was to investigate the dissolution behavior of levetiracetam from HPMC/Eudragit®NE matrices using magnesium aluminometasilicate (Neusilin® US2) as filler with excellent WAC. Part of this study was also to assess influence of thermal treatment on quality parameters of matrices. The use of Neusilin® allowed the application of Eudragit® dispersion to API/Neusilin® mixture in one step during high-shear wet granulation. HPMC was added extragranularly. Obtained matrices were investigated for qualitative characteristics, NMR solid-state spectroscopy (ssNMR), gel layer dynamic parameters, SEM, and principal component analysis (PCA). Decrease in burst effect (max. of 33.6%) and dissolution rate, increase in fitting to zero-order kinetics, and paradoxical reduction in gel layer thickness were observed with rising Eudragit® NE concentration. The explanation was done by ssNMR, which clearly showed a significant reduction of the API particle size (150–500 nm) in granules as effect of surfactant present in dispersion in dependence on Eudragit®NE amount. This change in API particle size resulted in a significantly larger interface between these two entities. Based on ANOVA and PCA, thermal treatment was not revealed as a useful procedure for this system. 相似文献
4.
Hussein O. Ammar Magdy Ibrahim Azza A. Mahmoud Rehab N. Shamma Nada M. El Hoffy 《AAPS PharmSciTech》2018,19(3):1001-1010
Non-ionic surfactant (NIS) based in situ forming vesicles (ISVs) present an affordable alternative to the traditional systems for the parenteral control of drug release. In this work, NIS based ISVs encapsulating tenoxicam were prepared using the emulsion method. Tenoxicam-loaded ISVs were prepared using a 22.31 full factorial experimental design, where three factors were evaluated as independent variables; type of NIS (A), molar ratio of NIS to Tween®80 (B), and phase ratio of the internal ethyl acetate to the external Captex® oil phase (C). Percentage drug released after 1 h, particle size of the obtained vesicles and mean dissolution time were chosen as the dependent variables. Selected formulation was subjected to morphological investigation, injectability, viscosity measurements, and solid state characterization. Optimum formulation showed spherical nano-vesicles in the size of 379.08 nm with an initial drug release of 37.32% in the first hour followed by a sustained drug release pattern for 6 days. DSC analysis of the optimized formulation confirmed the presence of the drug in an amorphous form with the nano-vesicles. Biological evaluation of the selected formulation was performed on New Zealand rabbits by IM injection. The prepared ISVs exhibited a 45- and 28-fold larger AUC and MRT values, respectively, compared to those of the drug suspension. The obtained findings boost the use of ISVs for the treatment of many chronic inflammatory conditions. 相似文献
5.
《Bioscience, biotechnology, and biochemistry》2013,77(9):1688-1693
The effects of carnauba wax addition on the physical state of palm kernel oil-in-water emulsions were investigated. The oil-in-water emulsion (40 wt% oil + 60 wt% aqueous phase) kept the liquid state at 25°C irrespective of the presence or absence of carnauba wax in the oil phase. The emulsion containing the wax transformed from the liquid state to the solid state by shearing after storage for 20 h at 4°C, although the liquid-solid transition was not observed for the emulsion not containing the wax upon the same treatment. The viscoelasticity of the solid emulsions was demonstrated by small-deformation mechanical testing. Analysis of flow behavior of the emulsions showed that the change in physical properties of the emulsion containing the wax at 4°C was caused by the shearing at a low shear rate, around 50 s?1–100 s?1. According to the transition from the liquid state to the solid state of the emulsion containing the wax, the aggregation of oil droplets was found to occur to a large extent. The results of differential scanning calorimetry and surface pressure–surface area isotherms suggested that triglyceride molecules of palm kernel oil were more oriented at the oil–water interfaces in the emulsions after the wax addition. Based on these results, it is thought that carnauba wax is important in destabilization of palm kernel oil-in-water emulsions by modifying the physical state of the oil triglyceride molecules at the interfaces. 相似文献
6.
Dinesh K. Yadav Sri Ramya Tata John Hunt Erik C. Cook Trevor P. Creamer Nicholas C. Fitzkee 《Biomolecular NMR assignments》2017,11(2):215-219
Calcineurin (CaN) plays an important role in T-cell activation, cardiac system development and nervous system function. Previous studies have demonstrated that the regulatory domain (RD) of CaN binds calmodulin (CaM) towards the N-terminal end. Calcium-loaded CaM activates the serine/threonine phosphatase activity of CaN by binding to the RD, although the mechanistic details of this interaction remain unclear. It is thought that CaM binding at the RD displaces the auto-inhibitory domain (AID) from the active site of CaN, activating phosphatase activity. In the absence of calcium-loaded CaM, the RD is disordered, and binding of CaM induces folding in the RD. In order to provide mechanistic detail about the CaM–CaN interaction, we have undertaken an NMR study of the RD of CaN. Complete 13C, 15N and 1H assignments of the RD of CaN were obtained using solution NMR spectroscopy. The backbone of RD has been assigned using a combination of 13C-detected CON-IPAP experiments as well as traditional HNCO, HNCA, HNCOCA and HNCACB-based 3D NMR spectroscopy. A 15N-resolved TOCSY experiment has been used to assign Hα and Hβ chemical shifts. 相似文献
7.
James S. Craigie Shawna L. MacKinnon John A. Walter 《Journal of applied phycology》2008,20(5):665-671
Aqueous extracts of Ascophyllum nodosum and several other brown seaweeds are manufactured commercially and widely distributed for use on agricultural crops. The
increasingly regulated international trade in such products requires that they be standardized and defined to a degree not
previously required. We examined commercially available extracts using quantitative 1H NMR and principal components analysis (PCA) techniques. Extracts manufactured over a 4-year period using the same process
exhibited characteristic profiles that, on PCA, clustered as a discrete group distinct from the other commercial products
examined. In addition to recognizing extracts made from different seaweeds, analysis of the 1H spectra in the 0.35–4.70 ppm region allowed us to distinguish amongst extracts produced from the same algal species by different
manufacturers. This result established that the process used to make an extract is an important variable in defining its composition.
A comparison of the 1H NMR integrals for the regions 1.0–3.0 ppm and 3.0–4.38 ppm revealed small but significant changes in the A. nodosum spectra that we attribute to seasonal variation in gross composition of the harvested seaweed. Such changes are reflected
in the PCA scores plots and contribute to the scatter observed within the data point cluster observed for Acadian soluble
extracts when all data are pooled. Quantitative analysis using 1H NMR (qNMR) with a certified external standard (caffeine) showed a linear relationship with extract concentration over at
least an order of magnitude (2.5–33 mg/mL; R
2 > 0.97) for both spectral regions integrated. We conclude that qNMR can be used to profile (or “fingerprint”) commercial
seaweed extracts and to quantify the amount of extract present relative to a suitably chosen standard.
Issued as NRCC no. 42,652. 相似文献
8.
Sosuke Yoshinaga Norihito Ishida Tatsuichiro Tsuji Akihiro Sonoda Kaori Yunoki Mitsuhiro Takeda Etsuko Toda Yuya Terashima Kouji Matsushima Hiroaki Terasawa 《Biomolecular NMR assignments》2018,12(2):259-262
FROUNT is a cytoplasmic protein that interacts with the membrane-proximal C-terminal regions (Pro-Cs) of the CCR2 and CCR5 chemokine receptors. The interactions between FROUNT and the chemokine receptors play an important role in the migration of inflammatory immune cells. Therefore, FROUNT is a potential drug target for inflammatory diseases. However, the structural basis of the interactions between FROUNT and the chemokine receptors remains to be elucidated. We previously identified the C-terminal region (residues 532–656) of FROUNT as the structural domain responsible for the Pro-C binding, referred to as the chemokine receptor-binding domain (CRBD), and then constructed its mutant, bearing L538E/P612S mutations, with improved NMR spectral quality, referred to as CRBD_LEPS. We now report the main-chain and side-chain 1H, 13C, and 15N resonance assignments of CRBD_LEPS. The NMR signals of CRBD_LEPS were well dispersed and their intensities were uniform on the 1H–15N HSQC spectrum, and thus almost all of the main-chain and side-chain resonances were assigned. This assignment information provides the foundation for NMR studies of the three-dimensional structure of CRBD_LEPS in solution and its interactions with chemokine receptors. 相似文献
9.
CHANTAL BROSSARD FLORENCE ROUSSEAU GENEVIÈVE LLAMAS JEAN-PIERRE DUMONT 《Journal of sensory studies》2002,17(6):511-525
This study aimed to check the hypothesis that aroma concentration in the aqueous phase of an oil-in-water emulsion controlled the odor intensity of single aroma compounds. A set of flavored oil-in-water emulsions, prepared according to a 22 experimental design (aroma concentration, oil volume fraction) with two central points, was assessed for odor intensity by a 24-member panel during four sessions. In each session, three of the four-studied aroma molecules (benzaldehyde, ethyl butyrate, linalool and acetophenone) were investigated. Whatever the aroma, the experimental data showed that the oil volume fraction of the emulsion (from 0.12 to 0.48) did not influence the odor intensity. For each emulsion composition, aroma concentrations at equilibrium in both phases were calculated using the oil-water partition coefficient of the compound. Odor intensities, estimated from aroma concentration in the aqueous phase using previously reported modeling of odor intensity above water solutions, were then compared to experimental data. It is confirmed that the perceived odor intensity is governed by the aroma concentration in the aqueous phase at the time of the trial and not by the averaged apparent concentration in the emulsion. 相似文献
10.
Rad23 functions in nucleotide excision repair and proteasome-mediated protein degradation. It has four distinct structural domains that are connected by flexible linker regions, including an N-terminal ubiquitin-like (UBL) domain that binds proteasomes. We report in this NMR study the 1H, 15N and 13C resonance assignments for the backbone and side chain atoms of the Rad23 UBL domain (Rad23UBL) with BioMagResBank accession number 25825. We find that a Rad23 proline amino acid (P20) located in a loop undergoes isomerization. The secondary structural elements predicted from the NMR data fit well to that of the Rad23UBL when complexed with E4 ubiquitin ligase Ufd2, as reported in a crystallographic structure. These complete assignments can be used to study the protein dynamics of the Rad23UBL and its interaction of with other ubiquitin receptors or proteasome subunits. 相似文献
11.
Nazimuddin Khan David Ban Pablo Trigo-Mourino Marta G. Carneiro Manfred Konrad Donghan Lee T. Michael Sabo 《Biomolecular NMR assignments》2018,12(1):11-14
Human guanylate kinase (hGMPK) is a critical enzyme that, in addition to phosphorylating its physiological substrate (d)GMP, catalyzes the second phosphorylation step in the conversion of anti-viral and anti-cancer nucleoside analogs to their corresponding active nucleoside analog triphosphates. Until now, a high-resolution structure of hGMPK is unavailable and thus, we studied free hGMPK by NMR and assigned the chemical shift resonances of backbone and side chain 1H, 13C, and 15N nuclei as a first step towards the enzyme’s structural and mechanistic analysis with atomic resolution. 相似文献
12.
Yotsanan Weerapol Sontaya Limmatvapirat Jurairat Nunthanid Pornsak Sriamornsak 《AAPS PharmSciTech》2014,15(2):456-464
A simple but novel mixed surfactant system was designed to fabricate a self-nanoemulsifying drug delivery system (SNEDDS) based on hydrophilic–lipophilic balance (HLB) value. The impacts of HLB and molecular structure of surfactants on the formation of SNEDDS were investigated. After screening various oils and surfactants, nifedipine (NDP)-loaded liquid SNEDDS was formulated with Imwitor® 742 as oil and Tween®/Span® or Cremophor®/Span® as mixed surfactant. Droplet size of the emulsions obtained after dispersing SNEDDS containing Tween®/Span® in aqueous medium was independent of the HLB of a mixed surfactant. The use of the Cremophor®/Span® blend gave nanosized emulsion at higher HLB. The structure of the surfactant was found to influence the emulsion droplet size. Solid SNEDDS was then prepared by adsorbing NDP-loaded liquid SNEDDS comprising Cremophor® RH40/Span® 80 onto Aerosil® 200 or Aerosil® R972 as inert solid carrier. Solid SNEDDS formulations using higher amounts (30–50% w/w) of Aerosil® 200 exhibited good flow properties with smooth surface and preserved the self-emulsifying properties of liquid SNEDDS. Differential scanning calorimetry and X-ray diffraction studies of solid SNEDDS revealed the transformation of the crystalline structure of NDP due to its molecular dispersion state. In vitro dissolution study demonstrated higher dissolution of NDP from solid SNEDDS compared with NDP powder. 相似文献
13.
Juranić N Nemutlu E Zhang S Dzeja P Terzic A Macura S 《Journal of biomolecular NMR》2011,50(3):237-245
Intramolecular correlations among the 18O-labels of metabolic oligophosphates, mapped by J-decoupled 31P NMR 2D chemical shift correlation spectroscopy, impart stringent constraints to the 18O-isotope distributions over the whole oligophosphate moiety. The multiple deduced correlations of isotopic labels enable
determination of site-specific fractional isotope enrichments and unravel the isotopologue statistics. This approach ensures
accurate determination of 18O-labeling rates of phosphometabolites, critical in biochemical energy conversion and metabolic flux transmission. The biological
usefulness of the J-decoupled 31P NMR 2D chemical shift correlation maps was validated on adenosine tri-phosphate fractionally 18O labeled in perfused mammalian hearts. 相似文献
14.
Yaowapa Kwamman Busakorn Mahisanunt Shingo Matsukawa Utai Klinkesorn 《Food biophysics》2016,11(2):165-175
The main objective of this work was to investigate the electrostatic interaction between lysolecithin and chitosan in two-layer tuna oil-in-water emulsions using nuclear magnetic resonance (NMR) spectroscopy. The influence of chitosan concentration on the stability and properties of these emulsions was also evaluated. The 5 wt% tuna oil one-layer emulsion (lysolecithin-stabilized oil droplets without chitosan) and two-layer emulsions (lysolecithin-chitosan stabilized oil droplets) containing 5 wt% tuna oil, 1 wt% lysolecithin and various chitosan concentrations (0.025–0.40 wt%) were prepared. The one-dimensional (1D) 31P and 1H NMR spectra of emulsions were then recorded at 25 °C. The results showed that addition of chitosan affected the stability and properties of lysolecithin-stabilized one-layer emulsions. The 31P NMR peak of the choline head group on lysolecithin molecules disappeared when chitosan was added at concentrations above neutralization concentration (> 0.05 wt%). The 1H NMR peak intensity monitoring free amino groups (?NH 3 +) of chitosan showed a strong positive linear relationship to the chitosan concentration with a high correlation coefficient (R2 ≈ 0.99). This 1H NMR peak in emulsions could not be detected for chitosan in emulsions lower than saturation concentration (< 0.15 wt%). These phenomena indicate an electrostatic interaction between lysolecithin and chitosan at droplet surface in emulsion and were consistent with the results from zeta-potential measurements. The T 2* relaxation time of the choline head group (N-(CH 3)3) signal of lysolecithin also confirmed that lysolecithin-chitosan electrostatic interaction occurs at the surface of oil droplets in two-layer emulsions. The results suggest that NMR spectroscopy can be used as an alternative method for monitoring the electrostatic interaction between surfactant and oppositely charged electrolytes or biopolymers in two-layer emulsions. 相似文献
15.
Thioredoxins (Trx) are ubiquitous proteins that regulate several biochemical processes inside the cell. Trx is an important player, displaying oxidoreductase activity and helping to keep and regulate the oxidative state of the cellular environment. Trx also participates in the regulation of many cellular functions, such as DNA synthesis, protection against oxidative stress, cell cycle and signal transduction. The oxidized Trx is the target for another set of proteins, such as thioredoxin reductase (TrR), which used the reductive potential of NADPH. The oxidized state of Trx also plays important role in regulation of redox state in the cells. In this regard, the oxidized form of Trx is a putative conformer that contributes to the cellular redox environment. Here we report the chemical shift assignments (1H, 13C and 15N) in solution at 15 °C. We also showed the secondary structure analysis of the oxidized form of yeast thioredoxin (yTrx1) as basis for future NMR studies of protein–target interactions and dynamics. The assignment was done at low concentration (200 µM) because it is important to keep intact the water cavity. 相似文献
16.
Yoshikazu Hattori David Heidenreich Yuki Ono Toshihiko Sugiki Kei-ichi Yokoyama Ei-ichiro Suzuki Toshimichi Fujiwara Chojiro Kojima 《Journal of biomolecular NMR》2017,68(4):271-279
The preparation of stable isotope-labeled proteins is important for NMR studies, however, it is often hampered in the case of eukaryotic proteins which are not readily expressed in Escherichia coli. Such proteins are often conveniently investigated following post-expression chemical isotope tagging. Enzymatic 15N-labeling of glutamine side chains using transglutaminase (TGase) has been applied to several proteins for NMR studies. 19F-labeling is useful for interaction studies due to its high NMR sensitivity and susceptibility. Here, 19F-labeling of glutamine side chains using TGase and 2,2,2-trifluoroethylamine hydrochloride was established for use in an NMR study. This enzymatic 19F-labeling readily provided NMR detection of protein-drug and protein–protein interactions with complexes of about 100 kDa since the surface residues provided a good substrate for TGase. The 19F-labeling method was 3.5-fold more sensitive than 15N-labeling, and could be combined with other chemical modification techniques such as lysine 13C-methylation. 13C-dimethylated-19F-labeled FKBP12 provided more accurate information concerning the FK506 binding site. 相似文献
17.
Sook Wah Chan Hamed Mirhosseini Farah Saleena Taip Tau Chuan Ling Chin Ping Tan 《Food biophysics》2013,8(4):273-281
Co-enzyme Q10 (CoQ10), a lipophilic compound that widely used in the food and pharmaceutical products was formulated in a κ-carrageenan coated oil-in-water (O/W) emulsion. In this work, we examined the solubility of CoQ10 in different carrier oils and effects of emulsifier type on the formation and stability of CoQ10-loaded O/W emulsion. Nine vegetable oils and four types of emulsifiers were used. CoQ10 was found significantly (p?<?0.05) more soluble in medium chain oils (coconut oil and palm kernel oil) as compared to other vegetable oils. The O/W emulsions were then prepared with 10 % (w/w) coconut oil and palm kernel oil containing 200 g CoQ10/L oil stabilized by 1 % (w/v) emulsifiers (sucrose laurate (SEL), sodium stearoyl lactate (SSL), polyglycerol ester (PE), or Tween 80 (Tw 80)) in 1 % (w/v) κ-carrageenan aqueous solution. Particle size distribution and physical stability of the emulsions were monitored. The droplet sizes (surface weighted mean diameter, D[3,2]) of fresh O/W emulsion in the range of 2.79 to 5.83 μm were observed. Irrespective of the oil used, results indicated that complexes of SSL/κ-carrageenan provided the most stable CoQ10-loaded O/W emulsion with smaller and narrower particle size distribution. Both macroscopic and microscopic observations showed that O/W emulsion stabilized by SSL/κ-carrageenan is the only emulsion that exhibited no sign of coalescence, flocculation, and phase separation throughout the storage period observed. 相似文献
18.
Ali Yilmaz Nils T. Nyberg Per Mølgaard Javad Asili Jerzy W. Jaroszewski 《Metabolomics : Official journal of the Metabolomic Society》2010,6(4):511-517
The aim of this study was to explore feasibility of 1H NMR metabolic fingerprinting for discrimination of authenticity of saffron using principal component analysis (PCA) modeling.
Authentic reference Iranian saffron (n = 31) and commercial samples (n = 32) were used. Cross-validated PCA models based on 1H NMR spectra of solutions prepared by direct extraction of grinded saffron with methanol-d
4 distinguished reference Iranian saffron samples from commercial samples that formed several distinct clusters, some of which
represent falsified samples as confirmed by microscopic analysis. The production sites and drying conditions of the authentic
reference Iranian samples were not reflected in the current dataset. Picrocrocin and glycosyl esters of crocetin emerged as
the most important 1H NMR markers of authentic saffron by using statistical correlation spectroscopy. In conclusion, 1H NMR spectra of saffron extracts combined with pattern recognition by PCA provide immediate means of unsupervised classification
of saffron samples. 相似文献
19.
Papapanagiotou PA Quinn H Molitor JP Nienow AW Hewitt CJ 《Biotechnology letters》2005,27(20):1579-1585
The use of a rapeseed oil emulsion feed, produced by a phase inversion temperature (PIT) process, produced more biomass, gave
a 3-fold increase in oil utilisation and a higher oxytetracycline titre but a higher residual oil concentration when compared
to a conventional fed-batch Streptomyces rimosus process fed with crude rapeseed oil. Importantly, microbial utilisation of the surfactant was confirmed for the first time. 相似文献
20.
Grage SL Strandberg E Wadhwani P Esteban-Martín S Salgado J Ulrich AS 《European biophysics journal : EBJ》2012,41(5):475-482
Many solid-state nuclear magnetic resonance (NMR) approaches for membrane proteins rely on orientation-dependent parameters,
from which the alignment of peptide segments in the lipid bilayer can be calculated. Molecules embedded in liquid-crystalline
membranes, such as monomeric helices, are highly mobile, leading to partial averaging of the measured NMR parameters. These
dynamic effects need to be taken into account to avoid misinterpretation of NMR data. Here, we compare two common NMR approaches:
2H-NMR quadrupolar waves, and separated local field 15N–1H polarization inversion spin exchange at magic angle (PISEMA) spectra, in order to identify their strengths and drawbacks
for correctly determining the orientation and mobility of α-helical transmembrane peptides. We first analyzed the model peptide
WLP23 in oriented dimyristoylphosphatidylcholine (DMPC) membranes and then contrasted it with published data on GWALP23 in
dilauroylphosphatidylcholine (DLPC). We only obtained consistent tilt angles from the two methods when taking dynamics into
account. Interestingly, the two related peptides differ fundamentally in their mobility. Although both helices adopt the same
tilt in their respective bilayers (~20°), WLP23 undergoes extensive fluctuations in its azimuthal rotation angle, whereas
GWALP23 is much less dynamic. Both alternative NMR methods are suitable for characterizing orientation and dynamics, yet they
can be optimally used to address different aspects. PISEMA spectra immediately reveal the presence of large-amplitude rotational
fluctuations, which are not directly seen by 2H-NMR. On the other hand, PISEMA was unable to define the azimuthal rotation angle in the case of the highly dynamic WLP23,
though the helix tilt could still be determined, irrespective of any dynamics parameters. 相似文献