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Sampling of quadrupolar-echo solid-state NMR spectra during a quadrupolar Carr-Purcell-Meiboom-Gill pulse sequence was undertaken.

The magnitudes and relative orientations of chemical shielding dipolar and J coupling tensors for isolated (super31)P-(supe31)P spin pairs was studied using iterative fitting of (super)31P magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectra. Results showed that iterative fitting of (super31)P MAS NMR spectra present in transition-metal phosphine complexes can accurately determine parameters for isotropic and anisotropic interactions of isolated (super31)P-(super31)P spin pairs. These further demonstrated that the orientation of the chemical shielding tensors relative to each other and relative to the internuclear axis can be accurately measured.

Accurate data on the chemical shielding anisotropy parameters, quadrupole coupling constant (CQ) and associated asymmetry parameter (eta-Q), shielding tensors and quadrupole coupling exhibiting relative orientation were derived using the MAS NMR method. The relationship between the shielding anisotropy delta(sub sigma) and CQ, and the structure of the VO4 tetrahedra were exhibited in two isomorphous metavanadates KVO3, NH4VO3 and TlVO3, and LiVO3 and alpha-NAO3. A comparative analysis of the accuracy of the data proves that the 51V MAS NMR method more effective than the NMR method.

A new method is described for obtaining information about the conformational dynamics of membrane-proteins by using solid-state NMR experiments of oriented samples. The method is shown for the antimicrobial peptaibol alamethicin for which combined analysis of anisotropic interactions for the [Aib.sub.8] residue has given information about helix-tilt angle, wobbling and oscillatory rotation around the helix axis in the membrane bound state.

A new method is developed for improving the resolution in the [super 15]N dimension of 1D [super 15]N and 2D [super 1]H - [super 15]N separated local field (SLF) experiments for oriented membrane protein systems. The resolution enhancement is necessary for assignment and structural exploitation of spectra for large oriented membrane proteins.

The [super 2]H magic angle spinning solid-state NMR spectroscopy technique is employed to examine the membrane-bound conformation of peptaibols with metal-deuterated [alpha]-amino isobutyric acids.

The versatility of optical control theory is utilized for the design of multiple-quantum magic-angle spinning experiments for quadrupolar nuclei. The experiment offers high-resolution solid-state NMR spectra of quadrupolar nuclei with half-integer nuclear spin, normally displaying significant line broadening due to the second-order term of the quadrupole coupling interaction.

The optimal control theory applied to the development of solid state NMR dipolar recouping experiments where the challenge is to minimize the loss of signal due to crystallite-orientation dependencies is reported. It is felt that the approach could have an impact on future solid-state NMR experiments.

Research was conducted to examine the hypothesis that 67Zn QCPMG NMR represents a feasible approach to study Zn2+ coordination in model complexes for metalloenzymes. The significant sensitivity enhancement of 67Zn QCPMG NMR approach as compared to QE NMR was proven to be a powerful method in studies of zinc complexes. It is anticipated that 67Zn QCPMG NMR will play a critical role in solid-state investigations of 67Zn-enriched metalloproteins.

INADEQUATE CR (composite refocusing) suitably attains high possible sensitivity through singular-value decomposition bound on the spin dynamics. This technique nearly doubles the sensitivity of INADEQUATE CR. The procedure is suitable for analysing the carbon skeleton of organic molecules in isotropic liquids. The sensitivity of 1H and 13C-detected INADEQUATE should be based on eliminating the quaternary pairs absent in 1H. The echo and antiecho parts of INADEQUATE CR contains different phi phases.

We present a new method to obtain information about the conformational dynamics of membrane- proteins using solid-state NMR experiments of oriented samples. By measuring the orientation-dependent 1H-15N dipole-dipole coupling, 15N anisotropic chemical shift, and 2H quadrupole coupling parameters for a single residue, it is possible to obtain information about the local dynamics of each residue in the protein. This may be interpreted on an individual basis or through models extended to study conformational motion of membrane-protein segments. The method is demonstrated for the antimicrobial peptaibol alamethicin for which combined analysis of anisotropic interactions for the Aib8 residue provides detailed information about helix-tilt angle, wobbling, and oscillatory rotation around the helix axis in the membrane bound state. This information is in very good agreement with coarse-grained MD simulations of the peptide in lipid bilayers. [ABSTRACT FROM AUTHOR]

We present the use of 2H magic-angle spinning (MAS) NMR on methyl-deuterated α-amino isobutyric acid (Aib) as a new method to obtain fast and accurate structural constraints on peptaibols in membrane-bound environments. Using nonoriented vesicle-reconstituted samples we avoid the delicate preparation of oriented samples, and the use of MAS ensures high sensitivity and thereby very fast acquisition of experimental spectra. Furthermore, given the high content (~40%) of Aib in peptaibols and the fact that the amino acid Aib may be synthesized from cheap starting materials, even in the case of 2H, or 13C, or 15N labeling, this method is ideally suited for studies of the membrane-bound conformation of peptaibols. [ABSTRACT FROM AUTHOR]

We present a new method to obtain information about the conformational dynamics of membrane-proteins using solid-state NMR experiments of oriented samples. By measuring the orientation-dependent (1)H-(15)N dipole-dipole coupling, (15)N anisotropic chemical shift, and (2)H quadrupole coupling parameters for a single residue, it is possible to obtain information about the local dynamics of each residue in the protein. This may be interpreted on an individual basis or through models extended to study conformational motion of membrane-protein segments. The method is demonstrated for the antimicrobial peptaibol alamethicin for which combined analysis of anisotropic interactions for the Aib(8) residue provides detailed information about helix-tilt angle, wobbling, and oscillatory rotation around the helix axis in the membrane bound state. This information is in very good agreement with coarse-grained MD simulations of the peptide in lipid bilayers.

We present the use of 2H magic-angle spinning (MAS) NMR on methyl-deuterated alpha-amino isobutyric acid (Aib) as a new method to obtain fast and accurate structural constraints on peptaibols in membrane-bound environments. Using nonoriented vesicle-reconstituted samples we avoid the delicate preparation of oriented samples, and the use of MAS ensures high sensitivity and thereby very fast acquisition of experimental spectra. Furthermore, given the high content ( approximately 40%) of Aib in peptaibols and the fact that the amino acid Aib may be synthesized from cheap starting materials, even in the case of 2H, 13C, or 15N labeling, this method is ideally suited for studies of the membrane-bound conformation of peptaibols.