Signal intensities in 1H–13C CP and INEPT MAS NMR of liquid crystals

Nowacka, Agnieszka; Bongartz, Nils; Ollila, O. H. Samuli; Nylander, Tommy; Topgaard, Daniel

doi:10.1016/j.jmr.2013.02.016

Cited by 84 publications

(110 citation statements)

References 65 publications

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“…In such cases, CP transfers may provide better performance over rINEPT because the CP transfer time can be set much shorter (about 1 ms or lower). A more detailed description of the dependence of CP and rINEPT intensities can be found for example, in the publications by Nowacka et al (31,32) and Gross et al (28).…”

Section: Resultsmentioning

confidence: 99%

Effect of cholesterol on the molecular structure and transitions in a clinical-grade lung surfactant extract

Andersson

Grey

Larsson

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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The lipid-protein film covering the interface of the lung alveolar in mammals is vital for proper lung function and its deficiency is related to a range of diseases. Here we present a molecular-level characterization of a clinical-grade porcine lung surfactant extract using a multitechnique approach consisting of 1 H-13 C solid-state nuclear magnetic spectroscopy, small-and wide-angle X-ray scattering, and mass spectrometry. The detailed characterization presented for reconstituted membranes of a lung extract demonstrates that the molecular structure of lung surfactant strongly depends on the concentration of cholesterol. If cholesterol makes up about 11% of the total dry weight of lung surfactant, the surfactant extract adopts a single liquid-ordered lamellar phase, L α(o) , at physiological temperatures. This L α(o) phase gradually changes into a liquid-disordered lamellar phase, L α(d) , when the temperature is increased by a few degrees. In the absence of cholesterol the system segregates into one lamellar gel phase and one L α(d) phase. Remarkably, it was possible to measure a large set of order parameter magnitudes |S CH | from the liquiddisordered and -ordered lamellar phases and assign them to specific C-H bonds of the phospholipids in the biological extract with no use of isotopic labeling. These findings with molecular details on lung surfactant mixtures together with the presented NMR methodology may guide further development of pulmonary surfactant pharmaceuticals that better mimic the physiological selfassembly compositions for treatment of pathological states such as respiratory distress syndrome.T he air-alveoli interface of human lungs consists of ∼100 m 2 of surface area covered by a 1-to 2-µm-thick film rich in lipids, generally referred to as lung surfactant (LS) (1, 2). The alveolar interfacial film has several important functions, including stabilizing the interface, allowing for area expansions and controlling diffusional transport (3-7). These functions strongly rely on the self-assembly structure, as well as on the mechanical, barrier, and surface properties of the dynamic LS interfacial layer, which in turn depend on its chemical composition and external conditions in terms of compression, hydration, and so on. The main components of LS are phospholipids, cholesterol, and the so-called surfactant proteins representing ∼80, 10, and 10 wt %, respectively (2).Deficiency of LS in the alveoli, or an imbalance of its chemical composition, induces a number of pathological conditions (8). For instance, neonatal respiratory distress syndrome affects prematurely born infants when LS is not yet matured or is completely lacking; this deficiency may be lethal if left untreated. In these cases, the most common treatment is intratracheal administration of an exogenous LS into the lungs (9). In case of acute respiratory distress syndrome the mortality is 35 to 45% (10) and an effective treatment is clearly lacking (8). An accurate characterization of the molecular structure and dynamics of endogenous an...

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Section: Resultsmentioning

confidence: 99%

Effect of cholesterol on the molecular structure and transitions in a clinical-grade lung surfactant extract

Andersson

Grey

Larsson

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…The DP spectrum generally shows resonances from all carbons in the sample and is here used as reference. Under the present experimental conditions, the DP signal is quantitative when the rotational correlation time τ c < 10 ns and gradually disappears at longer τ c (24). CP is efficient in boosting the signal of segments with slow (τ c > 0.1 ms) and/or anisotropic motions.…”

Section: Pt Ssnmr To Monitor Molecular Conformation and Dynamics Inmentioning

confidence: 67%

“…The CP signal is not observable for nearly isotropic reorientation (order parameter jS CH j < 0.01) with fast dynamics (τ c < 10 ns). However, the signal from mobile segments (τ c < 10 ns) is selectively enhanced in the INEPT spectra, whereas the INEPT signal is not visible for slower motion (τ c ≥ 0.1 μs) and/or highly anisotropic reorientation (jS CH j > 0.5) (24). The dependence of CP and INEPT intensities on τ c and jS CH j of the C-H bond reorientation is shown in SI Appendix, Fig.…”

Section: Pt Ssnmr To Monitor Molecular Conformation and Dynamics Inmentioning

confidence: 97%

“…Simultaneously, we obtain information on the molecular effects caused by the added solvent on SC lipid and protein components in the very same sample. The present NMR method is sufficiently sensitive to detect changes in the minor fraction of mobile components, and it also gives information on the major fraction of rigid components (11,24), thereby providing information on SC molecular dynamics with a molecular detail that has not been reachable before. In addition, it is possible to distinguish several coexisting fractions of the same type of molecular component with different molecular dynamics.…”

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confidence: 99%

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Tracking solvents in the skin through atomically resolved measurements of molecular mobility in intact stratum corneum

Pham

Topgaard

Sparr

2016

Proc. Natl. Acad. Sci. U.S.A.

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Solvents are commonly used in pharmaceutical and cosmetic formulations and sanitary products and cleansers. The uptake of solvent into the skin may change the molecular organization of skin lipids and proteins, which may in turn alter the protective skin barrier function. We herein examine the molecular effects of 10 different solvents on the outermost layer of skin, the stratum corneum (SC), using polarization transfer solid-state NMR on natural abundance 13C in intact SC. With this approach it is possible to characterize the molecular dynamics of solvent molecules when present inside intact SC and to simultaneously monitor the effects caused by the added solvent on SC lipids and protein components. All solvents investigated cause an increased fluidity of SC lipids, with the most prominent effects shown for the apolar hydrocarbon solvents and 2-propanol. However, no solvent other than water shows the ability to fluidize amino acids in the keratin filaments. The solvent molecules themselves show reduced molecular mobility when incorporated in the SC matrix. Changes in the molecular properties of the SC, and in particular alternation in the balance between solid and fluid SC components, may have significant influences on the macroscopic SC barrier properties as well as mechanical properties of the skin. Deepened understanding of molecular effects of foreign compounds in SC fluidity can therefore have strong impact on the development of skin products in pharmaceutical, cosmetic, and sanitary applications.

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“…5 C. The C-terminal helical region of IL-8 (1-66) does not show evidence of interaction with the receptor. It is known to be responsible for association with the sulfate groups of glycosaminoglycans (62), and local motions might occur on an intermediate timescale, such that neither CP nor INEPT transfers yield signals (63).…”

Section: Il-8 Interaction With Cxcr1 In Phospholipid Bilayersmentioning

confidence: 99%

Interaction of Monomeric Interleukin-8 with CXCR1 Mapped by Proton-Detected Fast MAS Solid-State NMR

Park

Berkamp

Radoicic

et al. 2017

Biophysical Journal

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The human chemokine interleukin-8 (IL-8; CXCL8) is a key mediator of innate immune and inflammatory responses. This small, soluble protein triggers a host of biological effects upon binding and activating CXCR1, a G proteincoupled receptor, located in the cell membrane of neutrophils. Here, we describe 1 H-detected magic angle spinning solid-state NMR studies of monomeric IL-8 (1-66) bound to full-length and truncated constructs of CXCR1 in phospholipid bilayers under physiological conditions. Cross-polarization experiments demonstrate that most backbone amide sites of IL-8 (1-66) are immobilized and that their chemical shifts are perturbed upon binding to CXCR1, demonstrating that the dynamics and environments of chemokine residues are affected by interactions with the chemokine receptor. Comparisons of spectra of IL-8 (1-66) bound to full-length CXCR1 (1-350) and to N-terminal truncated construct NT-CXCR1 (39-350) identify specific chemokine residues involved in interactions with binding sites associated with N-terminal residues (binding site-I) and extracellular loop and helical residues (binding site-II) of the receptor. Intermolecular paramagnetic relaxation enhancement broadening of IL-8 (1-66) signals results from interactions of the chemokine with CXCR1 (1-350) containing Mn 2þ chelated to an unnatural amino acid assists in the characterization of the receptor-bound form of the chemokine.

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Signal intensities in 1H–13C CP and INEPT MAS NMR of liquid crystals

Cited by 84 publications

References 65 publications

Effect of cholesterol on the molecular structure and transitions in a clinical-grade lung surfactant extract

Effect of cholesterol on the molecular structure and transitions in a clinical-grade lung surfactant extract

Tracking solvents in the skin through atomically resolved measurements of molecular mobility in intact stratum corneum

Interaction of Monomeric Interleukin-8 with CXCR1 Mapped by Proton-Detected Fast MAS Solid-State NMR

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