Uniform-sign cross-peak double-quantum-filtered correlation spectroscopy

Mueller, Leonard J.; Elliott, Douglas W.; Leskowitz, Garett M.; Struppe, Jochem; Olsen, Ryan A.; Kim, Kee‐Chan; Reed, Christopher A.

doi:10.1016/j.jmr.2004.03.017

Cited by 40 publications

(51 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To further enhance the spectral resolution and better distinguish the coil and sheet resonances, we carried out a 2D-correlation experiment, CTUC-COSY, [17] to assign the 13 C resonances. This experiment utilizes 13 C-…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Conformation, Dynamics, and Insertion of a Noncysteine‐Containing Protegrin‐1 Analogue in Lipid Membranes from Solid‐State NMR Spectroscopy

Mani¹,

Waring²,

Hong³

2007

ChemBioChem

View full text Add to dashboard Cite

Disulfide-bonded beta-hairpin structures are common among antimicrobial peptides. Disulfide bonds are known to be important for antimicrobial activity, but the underlying structural reason is not well understood. We have investigated the membrane-bound structure of a disulfide-deleted analogue of the antimicrobial peptide protegrin-1, in which the four Cys residues were replaced by Ala. The secondary structure, dynamics, and topology of this Ala-PG1 peptide in the membrane were determined by using magic-angle-spinning NMR spectroscopy. Conformation-dependent (13)C isotropic chemical shifts of multiple (13)C-labeled residues were obtained from 1D cross-polarization and direct-polarization spectra, and from 2D J-coupling-mediated (13)C-(13)C correlation spectra. Most labeled residues exhibited two conformations: a random coil and a beta-sheet structure. The dual-conformation property was present in both anionic lipid bilayers, which mimic the bacterial membrane, and zwitterionic cholesterol-containing bilayers, which mimic the eukaryotic cell membrane. The mobility of the peptide was measured by using a 2D C-H dipolar-shift correlation experiment. The random-coil fraction was highly mobile whereas the beta-sheet component was rigid. (1)H spin diffusion from the lipid chains to the peptide indicates that the beta-sheet component was well inserted into the anionic membrane, but surface bound in the cholesterol-containing neutral membrane. Thus, the removal of disulfide bonds changed some PG-1 molecules to highly mobile random coils that were poorly associated with the lipid membrane, but other molecules retained a beta-sheet conformation and had a similar membrane-binding topology to the parent peptide. Thus, the reduced antimicrobial activity of Ala-PG1 was largely due to the reduced number of insertion-competent beta-sheet molecules, rather than uniformly weakened activity of identically structured peptides.

show abstract

Section: Resultsmentioning

confidence: 99%

“…C J coupling to transfer the 13 C coherence, [17,18] which is necessary for observing cross peaks of mobile molecules. We combined the CTUC-COSY sequence with DP to detect the mobile portion of Ala-PG1 and with CP to detect the rigid component of the peptide.…”

mentioning

confidence: 99%

Conformation, Dynamics, and Insertion of a Noncysteine‐Containing Protegrin‐1 Analogue in Lipid Membranes from Solid‐State NMR Spectroscopy

Mani¹,

Waring²,

Hong³

2007

ChemBioChem

View full text Add to dashboard Cite

show abstract

“…This turned out not to be a problem of insufficient acid strength, but rather, a problem of oxidative/nucleophilic decomposition of the fullerene by the conjugate bases of the acids used. Even the usually nonoxidizing triflic acid was found to decompose C 60 32,33 to have a 1,2-carbocation static structure, 3. In solution, the appearance of a single sharp 13 C resonance indicates that the proton in the HC 60 + cation is a true ''globetrotter'', rapidly sampling attachment to all 60 carbon atoms.…”

Section: Protonated C 60mentioning

confidence: 99%

Carborane acids. New “strong yet gentle” acids for organic and inorganic chemistry

2005

Self Cite

View full text Add to dashboard Cite

Icosahedral carborane anions such as CHB 11 Cl 11 2 are amongst the least coordinating, most chemically inert anions known. They are also amongst the least basic, so their conjugate acids, H(carborane), are superacids (i.e. stronger than 100% H 2 SO 4 ). Acidity scale measurements indicate that H(CHB 11 Cl 11 ) is the strongest pure Brønsted acid presently known, surpassing triflic and fluorosulfuric acid. Nevertheless, it is also an extremely gentle acid-because its conjugate base engages in so little chemistry. Carborane acids separate protic acidity from anion nucleophilicity and destructive oxidative capacity in the conjugate base, to a degree not previously achieved. As a result, many long-sought, highly acidic, reactive cations such as protonated benzene (C 6 H 7 + ), protonated C 60 (HC 60 +), tertiary carbocations (R 3 C + ), vinyl cations (R 2 CLC + -R), silylium ions (R 3 Si + ) and discrete hydronium ions (H 3 O + , H 5 O 2 + etc.) can be readily isolated as carborane salts and characterized at room temperature by X-ray crystallography.

show abstract

“…in a linear A-B-C spin system with J AC = 0 Hz, A and C would appear correlated). These include the solid-state INADEQUATE [7,8] and INADEQUATE-CR [9], the refocused INADEQUATE [10], the UC2QF-COSY [11][12][13], spin-state selective experiments [14], and the recently introduced J-mediated triple-quantum (TQ) experiment [15]. In this paper, we focus on the refocused INADEQUATE experiment, whose robustness has been repeatedly demonstrated in a wide range of 13 C-enriched [16][17][18][19][20] or 15 N-enriched [21,22] and 13 C natural abundance [23][24][25][26][27][28] polycrystalline organic systems, as well as in disordered [29][30][31] organic systems and in crystalline and disordered inorganic solids [32][33][34][35][36].…”

Section: Introductionmentioning

confidence: 99%

The refocused INADEQUATE MAS NMR experiment in multiple spin-systems: Interpreting observed correlation peaks and optimising lineshapes

Cadars¹,

Sein²,

Duma³

et al. 2007

Journal of Magnetic Resonance

View full text Add to dashboard Cite

Uniform-sign cross-peak double-quantum-filtered correlation spectroscopy

Cited by 40 publications

References 35 publications

Conformation, Dynamics, and Insertion of a Noncysteine‐Containing Protegrin‐1 Analogue in Lipid Membranes from Solid‐State NMR Spectroscopy

Conformation, Dynamics, and Insertion of a Noncysteine‐Containing Protegrin‐1 Analogue in Lipid Membranes from Solid‐State NMR Spectroscopy

Carborane acids. New “strong yet gentle” acids for organic and inorganic chemistry

The refocused INADEQUATE MAS NMR experiment in multiple spin-systems: Interpreting observed correlation peaks and optimising lineshapes

Contact Info

Product

Resources

About