NMR-determined structures

Fig. 4.2 NMR-determined structure of a dodecamer duplex DNA complexed with cisplatin (left) and a close up of the induced damage (right). The kink is clearly visible and centred around the site of complexation. PDB entry 1A84.

Later, a larger set of 318 non-homologous chains representative of high-resolution structures became available (Sali Overington, 1994). All X-ray determined structures had a resolution of 2.3A or better (although some NMR-determined structures were also used), and no protein chains contained more than 30% sequence identity. All residues assigned by the DSSP program that were neither a helix (H) nor extended P sheet (E)... 

Due to its facility yielding abundant data, NMR is the most often used technique to reveal structural information on cryptands and cryptates. NMR determination structure is straightforward, but does not give as much structural detail as X-ray crystallography. 

Both cyclic and linear peptides have been studied by solid-state NMR, In some cases, comparisons can be made directly between solution and solid-state conformations and in others, direct comparisons between X-ray diffraction determined structures and NMR determined structures can be made, NMR data have also been used to describe the conformation of peptides in the solid-state in the absence of a prior diffraction analysis. 

X-ray diffraction. Solution calculatioas are al.so important as they allow for comparison with NMR determined structures along with a test of the influence of the absence of crystal contacts on the calculated structure. 

Although experimental studies of DNA and RNA structure have revealed the significant structural diversity of oligonucleotides, there are limitations to these approaches. X-ray crystallographic structures are limited to relatively small DNA duplexes, and the crystal lattice can impact the three-dimensional conformation [4]. NMR-based structural studies allow for the determination of structures in solution however, the limited amount of nuclear overhauser effect (NOE) data between nonadjacent stacked basepairs makes the determination of the overall structure of DNA difficult [5]. In addition, nanotechnology-based experiments, such as the use of optical tweezers and atomic force microscopy [6], have revealed that the forces required to distort DNA are relatively small, consistent with the structural heterogeneity observed in both DNA and RNA. 

Phosphorus has only one stable isotope, J P, and accordingly (p. 17) its atomic weight is known with extreme accuracy, 30.973 762(4). Sixteen radioactive isotopes are known, of which P is by far the most important il is made on the multikilogram scale by the neutron irradiation of S(n,p) or P(n,y) in a nuclear reactor, and is a pure -emitter of half life 14.26 days, 1.7()9MeV, rntan 0.69MeV. It finds extensive use in tracer and mechanistic studies. The stable isotope has a nuclear spin quantum number of and this is much used in nmr spectroscopy. Chemical shifts and coupling constants can both be used diagnostically to determine structural information. 

The zinc complexes of bis(2-pyridylmethyl)amine have been studied by X-ray crystallography and 13C NMR. The structures of [ZnL2](C104)2 and [ZnL2]Cl2-6II20 have been determined and 13C NMR demonstrated to be applicable to distinguishing the isomers.109... 

Spontaneous self assembly of a dinuclear triple helical complex is observed with linked bis-[4,5]-pineno-2,2 -bipyridines. Studies by electrospray mass spectrometry, CD and NMR determined that the major species in solution was a complex of Zn L = 2 3 stoichiometry with a triple helical structure and an enantiomerically pure homochiral configuration at the metal centers. The preference for the formation of one of the possible stereoisomers over the other is of interest.265 Another binuclear triple helical complex is formed from zinc addition to bis[5-(l-methyl-2-(6-methyl-2 -pyridyl)benzimidazolyl)]methane. Spectrophotometric titrations with a zinc solution... 

The combination of higher fields and pulsed, double resonance methods is now making it possible to use ESR as a tool to determine distances within macromolecules. This is a valuable supplement to the very widespread use of multi-dimensional NMR in structural biology.33... 

NMR, protein structure determination, 23, 275 non-enzymatic glycosylation, 14, 261 non-HIV antiviral agents, 36, 119, 38, 213 non-nutritive, sweeteners, V7, 323 non-peptide agonists, 32, 277 non-peptidic d-opinoid agonists, 37,159... 

Recently, the hydroxy derivatives of furan, thiophene, and selenophene have been studied with regard to their physical properties and reactions. These compounds are tautomeric and if the oxygen function is placed in the 2-position they exist as unsaturated lactones and undergo carbon-carbon rearrangement, whereas the 3-hydroxy derivatives form oxo-enol tautomeric systems. By NMR the structures of the different tautomeric forms have been determined as well as the position of the tautomeric equilibrium and the rate of isomerization. 

Fernandez C, Wuthrich K (2003) NMR solution structure determination of membrane proteins reconstituted in detergent micelles. FEBS Lett 555 144-150... 

As the temperature rises, partial decomposition of 110 occurs giving rise to GeC -) moieties which attack 110 providing 111 in low yields. Compound 110 was observed by NMR. The structure of 111 was determined by X-ray diffraction. 

Beek, J. D.v., Beaulieu, L., Schafer, H., Demura, M., Asakura, T., and Meier, B. H. (2000). Solid-state NMR determination of the secondary structure of Samia cynthia ddni silk. Nature 405, 1077-1079. 

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