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The binding of a 12-residue linear peptide, YW 12 rich in aromatic and aliphatic amino acid residues, to lipopolysaccharide (LPS) renders it a well-folded structure. The structural features of YW12 obtained from spectroscopic and fluorescence studies have indicated that interactions only with negative lipid micelles would be useful in the development of nontoxic antisepsis compounds.

Intermolecular nuclear Overhauser effects (NOEs) between the integral outer membrane protein OmpX from Escherichia coli and dihexanoylphosphatidylcholine (DHPC) provided a detailed description of protein-detergent interactions. The NOEs were measured in 3D [sup.15]N- and [sup.13]C-resolved [[sup.1]H, [sup.1]H]-NOESY spectra recorded with selectively methyl-protonated and otherwise uniformly [sup.2]H [sup.13]C, [sup.15]N-labeled OmpX in micelles of DHPC at natural isotope abundance. In these mixed micelles the NMR structure of OmpX consists of an eight-stranded antiparallel [beta]-barrel. The OmpX surface area covered with intermolecular NOEs to the DHPC hydrophobic tails forms a continuous cylinder jacket of approximately 28 [Angstrom] in height, which is centered about the middle of the long axis through the [beta]-barrel. In addition, some intermolecular NOEs with methyl groups of the DHPC polar head were identified along both boundaries of this cylinder jacket. The experimental data suggest that the hydrophobic surface areas of OmpX are covered with a monolayer of DHPC molecules, which appears to mimic quite faithfully the embedding of the [beta]-barrel in a double-layer lipid membrane. NOE | detergents | solvation of membrane proteins | intermolecular NOEs

Various aspects of transport and kinetics of nuclear magnetic resonance images obtained in a magnetic field of 16 mT are studied. An Overhauser imaging is used to monitor the resulting spatial and temporal evolution of the gelation of sodium alginate by calcium ions.

Research was conducted to examine lipid organization in biological membranes using two-dimensional nuclear Overhauser enhancement spectroscopy 1H NMR spectra recorded with magic-angle spinning. The cross-relaxation rates between all the lipid resonances were quantitatively analyzed and the amount of intermolecular contributions to cross-relaxation were determined. Results indicate that the interactions between lipid protons are intermolecular.

A pulse scheme is developed and used for recording nuclear Overhauser effects (NOEs) from valine and isoleucine methyl groups to proximal protons. The method offers significantly improved resolution in comparison with other 13C-edited experiments because both the indirectly identified dimensions are recorded in constant-time mode. The utility of the pulse scheme can be seen with applications on a fully protonated 15N,13C-labeled sample and a methyl protonated, 15N,13C,2H-labeled complex of 42 kDa.

A study was conducted to analyze NADH conformation bound to inosine 5'-monophosphate dehydrogenase using transferred nuclear overhauser effect spectroscopy. An Indigo II Silicon Graphics computer was utilized to analyze nuclear magnetic resonance data while the adenosine and dihydronicottinamide riboside moieties of NADH were analyzed separately. Results showed that the glycosidic conformations of nitoinamide-ribose and adenosine moieties are anti.

The water-nuclear Overhauser enhancement spectroscopy (NOESY) and water-rotating frame NOESY (ROESY) spectra of the protease/DMP323 complex exhibited the large water-proton distances that characterizes H2O hydration. The 430/480 symmetry-related water molecules exhibited short residence times and internuclear distances that are higher the 2.5 angstrom. The local fluctuations that were exhibited by the protease/DMP323 complex also indicated the presence of H-D solvent exchange in inhibitor hydroxyl protons.

The conformational and dynamic behavior of the linear peptide Y-Q-N-P-D-G-S-Q-A was characterized using nuclear magnetic resonance and computational modeling methods. Observations showed that the peptide's conformational equilibrium in water at five degrees Celsius is a function of several closely-related beta-hairpin conformers. The ensemble-averaged simulated annealing results verified this conclusion. Hydrogen bonding interactions and a proline residue limit the peptide's conformational space.

A study was conducted on the use of intra- and intermolecular 1H{1H}-nuclear Overhauser (nOe) effects for establishing the structure of transient bimolecular complexes. NOe data were combined with chromatographic data to obtain the characterizations. The approach enabled the construction of a chiral recognition model accounting for the ability of CSP 3 to differentiate between the enantiomers of analytes.

gVIIIp, the lipid-bound conformation of the major coat protein of bacteriophage M13, is examined by studying the protein with sodium dodecyl sulfate, SDS, detergent micelles. Three-dimensional heteronuclear NMR is used to obtain good quality spectra with a full set of resonance values. Two alpha-helical areas are seen in gVIIIp in an examination of the nuclear Overhauser effect and the information on chemical shift. A monomeric protein is observed when the SDS is high in comparison to the protein ratio.

The synthesis of three dioxaphospholenes with an aryl group as the fifth P(V) ligand allows the study of their pseudorotation behavior, configuration and conformation. The spectroscopic study suggests a strong resistance against pseudorotation below 60 degrees C, with the triphenyl form exhibiting the highest pseudorotational free energy value ever known. Nuclear Overhauser effect spectroscopic signals point to a cis configuration for the exocyclic phenyl in the dimethylphenyl form. Finally, conformational analysis of the spectra suggests a twist-envelope shape for the ephedrine-based five-membered saturated ring.

The distribution of rotamer probability about a dihedral angle was studied by Continuous Probability Distribution (CUPID). An equation was presented involving vicinal nuclear spin-spin coupling constants and dihedral angles. The rotationally averaged nuclear Overhauser enhancement was expressed as anintegral which can be solved by expanding the exponential terms in a Fourier series. Angular probability distribution, linear regression and Gaussian curves were some of the techniques used in CUPID.

The dependence of simulated nuclear Overhauser effect (NOE) on various helical parameters that are consistent with experimental NOESY spectra was investigated. A method for solving DNA oligomer solution structures from NOE data was developed and applied to self-complementary hexadeoxyribonucleotide d-(GGATCC)2. This approach incorporates full matrix NOESY simulation for a DNA structure and generation of double helical DNA conformation.

A study of the process of polypeptide hydration in mixed solutions showed wide variations in the residence time of hydration water molecules. Nuclear magnetic resonance (NMR) spectroscopy was used to determine hydration of nonapeptide oxytocin dissolved in a blended solvent containing 60% H(sub2)O and 40% (super2)H(sub6)acetone. Changes in hydration water molecules attached to peptide atoms can be explained by variations in the nuclear Overhauser effects (NOEs) between 0-15 degree Celsius.

The selective inversion-recovery of a chosen site A, combined with a selective transfer of magnetization to a different site X via a scalar coupling J(sub AX), was used to measure longitudinal relaxation rates. Cross-relaxation rates in a spin-locking field may be estimated by the ROESY method to quantify sigma(super t)(sub AX) and complemented with the self-relaxation rates rho(super t)(sub A) and rho(super t)(sub X), which are also known as the rotating frame relaxation rates 1/T(sub 1 rho)(super A) and 1/T(sub 1 rho)(super X). These rates may be measured via selective spin-locking of the target magnetization.

[sup.19]F nuclear Overhauser effects (NOEs) between fluorine labels on the cytoplasmic domain of rhodopsin solubilized in detergent micelles are reported. Previously, high-resolution solution [sup.19]F NMR spectra of fluorine-labeled rhodopsin in detergent micelles were described, demonstrating the applicability of this technique to studies of tertiary structure in the cytoplasmic domain. To quantitate tertiary contacts we have applied a transient one-dimensional difference NOE solution [sup.19]F NMR experiment to this system, permitting assessment of proximities between fluorine labels specifically incorporated into different regions of the cytoplasmic face. Three dicysteine substitution mutants (Cys-140-Cys-316, Cys-65-Cys-316, and Cys-139-Cys-251) were labeled by attachment of the trifluoroethylthio group through a disulfide linkage. Each mutant rhodopsin was prepared (8-10 mg) in dodecylmaltoside and analyzed at 20 [degrees] C by solution [sup.19]F NMR. Distinct chemical shifts were observed for all of the rhodopsin [sup.19]F labels in the dark. An up-field shift of the Cys-316 resonance in the Cys-65-Cys-316 mutant suggests a close proximity between the two residues. When analyzed for [sup.19]F-[sup.19]F NOEs, a moderate negative enhancement was observed for the Cys-65-Cys-316 pair and a strong negative enhancement was observed for the Cys-139-Cys-251 pair, indicating proximity between these sites. No NOE enhancement was observed for the Cys-140-Cys-316 pair. These NOE effects demonstrate a solution [sup.19]F NMR method for analysis of tertiary contacts in high molecular weight proteins, including membrane proteins.

Structure of a Psoralen Cross-Linked DNA in Solution by Nuclear Magnetic Resonance PSORALENS (FIG. 1A) ARE A CLASS OF furocoumarins (1) that are used for treatment of psoriasis and other [...]

A study on the nuclear Overhauser effect (NOE) in low-viscous liquids in relation to diffusion coefficient calculations performed a series of diffusion studies on a mixture of 150 millimicron human serum albumin, 10 mM benzoic acid and 10 mM glucose in D2O. The interaction between binding ligand benzoic acid and human serum albumin furnishes a method to track intermolecular NOE effect on the diffusion measurement. Results are discussed.

A novel method that allows the clear and definitive detection of ligands that bind to a macromolecule is proposed. This diffusion-assisted nuclear Overhauser effect (NOE)-pumping experiment involves distinguishing from non-binding ligands those molecules that can bind to the macromolecule, using NOE to transfer the signal from the receptor to the bound ligands. Among the advantages of the method are the elimination of false positives and the lack of influence of any chemical shift changes in the spectrum owing to any variation in the chemical environment on the result.

Pulsed field gradients, which avoid calculation of difference spectra, measure transient nuclear Overhauser effect (NOE) enhancements. The resultant spectra have no subtraction artifacts. This technique enables the identification of very small NOE enhancements efficiently. The advantages of this technique are analyzed.

A practical solution to the ambiguity between the nuclear Overhauser enhancement (NOE) signals of intra- and intersubunits of symmetrical dimeric proteins is described. The technique involves mixing uniformly 13C-labeled and unlabeled dimers. The resulting homo- and heterodimer mixes undergo two sets of NOESY runs, one where both 13C 180-degree editing pulses are applied and one in which they are both omitted. Substraction of these two data sets yields separate NOE cross-peaks between 13C- and 12C-bound protons and, hence, a subspectrum containing only the desired intersubunit NOEs.

The nature of chaperonin-substrate recognition was investigated by using nuclear magnetic resonance (NMR) methods to determine how chaperonins recognize a large number of structurally unrelated polypeptides in their unfolded or partially folded forms. Results provided support for the view that the molecular basis of GroEL-substrate recognition was the presentation of a hydrophobic surface by an incompletely folded polypeptide. The results also demonstrated that many backbone conformations could be accommodated.