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The switchgrass (SG) samples pretreated by cellulose solvent- and organic solvent-based lignocellulose fractionation were characterized by enzymatic hydrolysis, substrate accessibility assay, scanning electron microscopy, X-ray diffraction (XRD), cross polarization/magic angle spinning (CP/MAS) (13)C nuclear magnetic resonance (NMR), and Fourier transform(More)
Membrane pores that are induced in oriented membranes by an antimicrobial peptide (AMP), protegrin-1 (PG-1), are investigated by (31)P and (2)H solid state NMR spectroscopy. We incorporated a well-studied peptide, protegrin-1 (PG-1), a beta-sheet AMP, to investigate AMP-induced dynamic supramolecular lipid assemblies at different peptide concentrations and(More)
Nonsecular dipolar couplings between spin2 nuclei that are in close proximity to quadrupolar spins have been extensively documented in solid state nuclear magnetic resonance ~NMR!, particularly when involving directly bonded S5C, I5N spin pairs. These couplings arise due to the quadrupole-induced tilting of I’s nuclear spin quantization axes, and their most(More)
Dynamic structures of supramolecular lipid assemblies, such as toroidal pores and thinned bilayers induced in oriented lipid membranes, which are interacting with membrane-acting antimicrobial peptides (AMPs), magainin-2 and aurein-3.3, were explored by 31P and 2H solid-state NMR (ssNMR) spectroscopy. Various types of phospholipid systems, such as POPC-d31,(More)
Second-order dipolar effects arise when a nucleus S is in close proximity to a quadrupolar spin I. These couplings originate from cross correlations between quadrupolar and dipolar interactions, and have the notable characteristic of not being susceptible to averaging by magic-angle-spinning. Therefore they can originate noticeable splittings in high(More)
RTD-1 is a cyclic beta-hairpin antimicrobial peptide isolated from rhesus macaque leukocytes. Using (31)P, (2)H, (13)C, and (15)N solid-state NMR, we investigated the interaction of RTD-1 with lipid bilayers of different compositions. (31)P and (2)H NMR of uniaxially oriented membranes provided valuable information about how RTD-1 affects the static and(More)
Water-soluble derivatives of gadolinium-containing metallofullerenes have been considered to be excellent candidates for new magnetic resonance imaging (MRI) contrast agents because of their high relaxivity and characteristic encapsulation of the lanthanide ions (Gd(3+)), preventing their release into the bioenvironment. The trimetallic nitride template(More)
Cross-polarization magic-angle spinning (CPMAS) experiments employing frequency-swept pulses are explored within the context of obtaining broadband signal enhancements for rare spin S = 1/2 nuclei at very high magnetic fields. These experiments employ adiabatic inversion pulses on the S-channel ((13)C) to cover a wide frequency offset range, while(More)
Cross-polarization (CP) experiments employing frequency-swept radiofrequency (rf) pulses have been successfully used in static spin systems for obtaining broadband signal enhancements. These experiments have been recently extended to heteronuclear I, S = spin-1/2 nuclides under magic-angle spinning (MAS), by applying adiabatic inversion pulses along the S(More)
We report the experimental determination of the 13CR chemical shift tensors of Ala, Leu, Val, Phe, and Met in a number of polycrystalline peptides with known X-ray or de novo solid-state NMR structures. The 700 Hz dipolar coupling between 13CR and its directly bonded 14N permits extraction of both the magnitude and the orientation of the shielding tensor(More)