“Enantiodifferentiation through Frequency-Selective Pure-Shift 1H Nuclear Magnetic Resonance Spectroscopy” by Laura Castañar, Míriam Pérez-Trujillo, Pau Nolis, Eva Monteagudo, Albert Virgili and Teodor Parella. ChemPhysChem,15 (2014) 854-857.
A frequency-selective 1D 1H NMR experiment for the fast and sensitive determination of chemical shift differences between overlapped resonances is proposed. The resulting fully homodecoupled 1H resonances appear as resolved 1D singlets without their typical JHH multiplet structure. The achieved high signal dispersion is here exploited in enantiodiscrimination studies using chiral solvating agents. We have demonstrated that the homodecoupled SPFGE method is a robust and sensitive analytical NMR spectroscopy tool for the fast and simple discrimination of chemical-shift differences in overlapped signals and for the determination of the ee in the presence of CSAs. Its major advantage lies in the single-scan and 1D acquisition modes, as the resulting simplified singlet signals facilitate a better analysis. It has been shown that homodecoupled signals can also be retrieved for resonances obscured by other more intense signals or in overcrowded regions by using a preparatory TOCSY editing.
“Full sensitivity and enhanced resolution in homodecoupled band-selective NMR experiments” by L. Castañar, P. Nolis, A. Virgili and T. Parella. Chem. Eur. J. 2013, 19, 17283-17286. DOI:10.1002/chem.201303235
“Drought enhances folivory by shifting foliar metabolomes in Quercus ilex trees”
Albert Rivas-Ubach, Albert Gargallo-Garriga, Jordi Sardans, Michal Oravec, Laia Mateu Castell, Míriam Pérez-Trujillo,Teodor Parella, Romà Ogaya, Otmar Urban and Josep Peñuelas. January 2014. New Phytologist DOI: 10.1111/nph.12687
Plants respond to external environmental conditions such as drought or to the seasonal changes by shifting the foliar C:N:P:K stoichiometry and metabolome. Rates of folivory are usually associated with the water status of plants and/or concentrations of foliar nutrients, especially N, but studies have focused mainly on the concentrations of foliar nutrients or on particular foliar-specific metabolic families. Emerging ecometabolomic techniques allow the study of metabolomes, the total set of metabolites in an organism at a specific moment. This study attempts to integrate stoichiometric and metabolomic techniques, based on NMR spectroscopy and MS spectrometry, to understand the responses of Quercus ilex throughout seasons and under moderate experimental conditions of drought and how these responses affect rates of folivory. Foliar K concentrations increased in summer, the driest Mediterranean season. This increase was expected because K acts as an osmoprotectant under water stress, which consequently leads to higher foliar K/P and lower C/K and N/K ratios. These changes in summer were also accompanied by higher concentrations of phenolic compounds related to antioxidant functions. Moreover, trees exposed to a moderate drought in the field had higher foliar concentrations of total sugars and polyphenolic compounds (flavonoids). These compounds were mainly associated with the avoidance of water stress: sugars that provide osmotic protection, and flavonoids that act as antioxidants. Folivory increased in the trees of the droughted plots. Our data suggest that the increase of sugars and flavonoids in Q. ilex leaves in droughted trees can lead to an increase in herbivorous attack, which implies an indirect relationship between increased drought and rate of folivory produced by metabolomic shifts. The present study represents an advance in understanding the potential cascade effects of drought at different trophic levels and their possible implications in the structure, function and evolution of ecosystems.
“Straightforward measurement of individual 1J(CH) and 2J(HH) in diastereotopic CH2 groups” by Josep Saurí, Laura Castañar, Pau Nolis, Albert Virgili and Teodor Parella. Journal of Magnetic Resonance 242 (2014) 33–40. DOI: 10.1016/j.jmr.2014.02.003
The C-HA cross-peak corresponding to a diastereotopic CHAHB methylene spin system exhibits a characteristic 1:0:1 multiplet pattern along the indirect dimension of a ω1-coupled HSQC spectrum. It is shown here that the use of the initial 13C Boltzmann polarization instead of the regular INEPT-based 1H Boltzmann polarization makes visible the central lines of this multiplet pattern. A spin-state-selective method is proposed for the efficient measurement of both 1J(CHA) and 1J(CHB) along the indirect dimension of a 2D spectrum as well as to the magnitude and the sign of the geminal 2J(HAHB) coupling constant from the straightforward analysis of a single four-component E.COSY cross-peak. Additionally, the extraction of1J(CH) values for CH and CH3 multiplicities can be also performed from the same spectrum. The success of the method is also illustrated for the determination of residual dipolar 1D(CH) and 2D(HH) coupling constants in a small molecule weakly aligned in a PMMA swollen gel.
Pulse Program Code for Bruker:
Data set Example:
- Date: Thursday 13th February, 2014
- Hour: 10 am
- Location: SeRMN, Facultats de Ciències i Biociències, C2/-135
- Speaker: Miquel Cabañas, SeRMN
CcpNmr Analysis is a graphics-based interactive NMR spectrum visualisation, resonance assignment and data analysis program developed by The Collaborative Computing Project for NMR. as part of the CcpNmr suite of programs. CcpNmr Analysis can be considered a platform for almost all the NMR data described by the CCPN data model and a place from which to interact with connected non-CCPN programs, for example those integrated in the Extend-NMR project. CcpNmr.
Aimed at macromolecular NMR, it could prove a useful tool for the assignment of nmr spectra of smaller compounds or reaction mixtures. The software features will be demonstrated at the seminar and its suitability for organic chemistry nmr will be discussed.
- The CCPN data model for NMR spectroscopy: development of a software pipeline. Vranken WF, Boucher W, Stevens TJ, Fogh RH, Pajon A, Llinas M, Ulrich EL, Markley JL, Ionides J, Laue ED. Proteins. 2005, 59(4):687-696. DOI: 10.1002/prot.20449
- The CCPN Metabolomics Project: a fast protocol for metabolite identification by 2D-NMR. Chignola F, Mari S, Stevens TJ, Fogh RH, Mannella V, Boucher W, Musco G. Bioinformatics. 2011, 27(6):885-886. DOI: 10.1093/bioinformatics/btr013
- A software framework for analysing solid-state MAS NMR data. Stevens TJ, Fogh RH, Boucher W, Higman VA, Eisenmenger F, Bardiaux B, van Rossum BJ, Oschkinat H, Laue ED. J Biomol NMR. 2011, 51(4):437-447. DOI: 10.1007/s10858-011-9569-2
“Factors Secreted by Endothelial Progenitor Cells Enhance Neurorepair Responses after Cerebral Ischemia in Mice” by Rosell, A., Morancho, A., Navarro-Sobrino, M., Martínez-Saez, E., Hernández-Guillamon, M., Lope-Piedrafita, S., Barceló, V., Borrás, F., Penalba, A., García-Bonilla, L., Montaner, J. PLoS ONE 8 (2013), e73244. DOI: 10.1371/journal.pone.0073244
Cell therapy with endothelial progenitor cells (EPCs) has emerged as a promising strategy to regenerate the brain after stroke. The aim of this study was to investigate if treatment with EPCs or their secreted factors could potentiate angiogenesis and neurogenesis after permanent focal cerebral ischemia in a mouse model of ischemic stroke. Magnetic resonance imaging (MRI) was performed at baseline (24 hours after ischemia and before any treatment was administered) to confirm that the severity of the lesions was similar between groups as measured by infarct volume, transverse relaxation time (T2), apparent diffusion coefficient (ADC) and fractional anisotropy (FA). Severe lesions were observed on T2 weighted images (T2 WI) at two weeks after ischemia with a complete atrophy of the injured cortex.
Immunohistochemistry and histology of the brain were performed to evaluate angio-neurogenesis and neurological outcome at two weeks. A significant increase in capillary density was noted in the peri-infarct areas of animals treated with EPC and also in those treated only with secreted factors of the EPCs. At the functional level, post-ischemia forelimb strength was significantly improved in animals receiving EPCs or EPC-secreted factors. In conclusion, this work demonstrates for the first time that the administration of EPC-secreted factors could become a safe and effective cell-free option to be considered in future therapeutic strategies for stroke.
- Date: Monday 16th December, 2013
- Hour: 10 am
- Location: SeRMN, Facultats de Ciències i Biociències, C2/-135
- Speaker: Laura Castañar, SeRMN PhD Student & Teaching Assistant, Dept. of Chemistry.
A NMR pulse scheme that provides full sensitivity in homodecouped band-selective NMR experiments is proposed. The easy implementation of this HOBS scheme as a general building block into a great variety of multidimensional NMR experiments leads to pure-shift spectra with enhanced resolution and with the maximum attainable sensitivity.
“Full sensitivity and enhanced resolution in homodecoupled band-selective NMR experiments” by L. Castañar, P. Nolis, A. Virgili and T. Parella. Chem. Eur. J. 2013, 19, 17283-17286. DOI: 10.1002/chem.201303235
Structural evolution upon decomposition of the LiAlH4+LiBH4 system. S. Soru, A. Taras, C. Pistiddb, C. Milanese, C. Bonatto Minella, E. Masolo, P. Nolis, M. D. Baró, A. Marinic, M. Tolkiehn,M. Dornheim, S. Enzo, G. Mulas, S. Garroni. Journal of Alloys and Compounds 2014, in press. DOI: 10.1016/j.jallcom.2013.12.027
In the present work we focus the attention on the phase structural transformations occurring upon the desorption process of the LiBH4 + LiAlH4 system. This study is conducted by means of manometric-calorimetric, in-situ Synchrotron Radiation Powder X-ray Diffraction (SR-PXD) and ex-situ Solid State Magic Angle Spinning (MAS) Nuclear Magnetic Resonance (NMR) measurements. The desorption reaction is characterized by two main dehydrogenation steps starting at 320 and 380°C, respectively. The first step corresponds to the decomposition of LiAlH4 into Al and H2via the formation of Li3AlH6 whereas the second one refers to the dehydrogenation of LiBH4 (molten state). In the range 328-380 °C, the molten LiBH4 reacts with metallic Al releasing hydrogen and forming an unidentified phase which appears to be an important intermediate for the desorption mechanism of LiBH4 -Al-based systems. Interestingly, NMR studies indicate that the unknown intermediate is stable up to 400°C and it is mainly composed of Li, B, Al and H. In addition, the NMR measurements of the annealed powders (400 °C) confirm that the desorption reaction of the LiBH4 + Al system proceeds via an amorphous boron compound.
A NMR method to enhance the sensitivity and resolution in band-selective long-range heteronuclear correlation spectra is proposed. The excellent in-phase nature of the selHSQMBC experiment allows that homonuclear and/or heteronuclear decoupling can be achieved in the detected dimension of a 2D multiple-bond correlation map, obtaining simplified cross-peaks without their characteristic fine J multiplet structure. The experimental result is a resolution improvement while the highest sensitivity is also achieved. Specifically, it is shown that the 1H-homodecoupled band-selective (HOBS) HSQMBC experiment represents a new way to measure heteronuclear coupling constants from the simplified in-phase doublets generated along the detected dimension.
Pulse Programs Code for Bruker:
Data set Example:
“Full sensitivity and enhanced resolution in homodecoupled band-selective NMR experiments” by L. Castañar, P. Nolis, A. Virgili and T. Parella. Chem. Eur. J. 2013, 19, 17283-17286. DOI: http://dx.doi.org/10.1002/chem.201303235
“13C NMR spectroscopy for the differentiation of enantiomers using chiral solvating agents” Míriam Pérez-Trujillo, Eva Monteagudo and Teodor Parella. Analytical Chemistry, 2013, 85 (22), pp 10887–10894. DOI: 10.1021/ac402580j
The utility of 13C NMR spectroscopy for the differentiation of enantiomers using chiral solvating agents (CSA) is stated. Three examples involving the enantiodifferentiation of a drug, a metabolite and a reactant in aqueous and organic solutions have been chosen to show it. Continue reading