Proposal structure of the

Fig. 6 Proposed structure of the antigenic epitopes in the ramified region of bupleuran 211c for anti-bupleuran 211c/PG-l-lgG as proposed by Sakurai et al. [49]...

Figure 6 Proposed structure of the Bu2Sn(IV)-rutin complex of 1 1 molar ratio/...

Fig. 2. Protein backbone representations of (a) the 2[4Fe-4S] ferredoxin from Peptococcus aerogenes, (b) the proposed structure of the FA/FB-binding protein of PSl based on the 4 A crystsd structure (25), and (c) the [3Fe-4S][4Fe-4S] ferredoxin from Sulfolo-bus acidocaldarius. Ligands to clusters Fa and Fb, important residues as well as the loop extension (see text) EU e highlighted in darker gray.

Fig. 7. A proposed structure of the complex of the antibody with the trivalent antigen immobilized on the surface of the sensor chip...

Figure 8.6 Schematic diagram of the proposed structure of the vesicular monoamine transporter. There are 12 transmembrane segments with both the N- and C-termini projecting towards the neuronal cytosol. (Based on Schuldiner 1998)...

Fig. 17. Proposed structure of the PVA-polyiodide inclusion compound. The polymer chain is shown as a helical line with appended hydroxyl groups and bridging borate groups. The stippled core represents the polyiodide guest chain...

Fig. 24. Proposed structure of the Gramicidin A dimer showing the intramolecular and intermolecular hydrogen bonding arrangement. Numbers refer to the amino acid residues Peptide side groups are omitted for clarity.

The structure elucidation of the kinamycins was a formidable challenge, and the information presented below draws from the work of several research groups over a period of more than 20 years. As will be shown, the originally proposed structure of the kinamycins contained a cyanamide rather than a diazo function. Subsequent synthetic and biosynthetic studies led to replacement of the cyanamide with a diazo function. The structural elucidation was challenging, in part, because of the high degree of unsaturation of the kinamycins, which limits the utility of H and 2D NMR analysis. In addition, because these structures were unprecedented, there were no clear benchmarks for comparison at the time. The pathway from isolation to determination of the correct structure is described below. 

Kakuta, Y., Tahara, M., Maetani, S., Yao, M., Tanaka, I., and Kimura, M. (2004). Crystal structure of the regulatory subunit of archaeal initiation factor 2B (aIF2B) from hyper-thermophilic archaeon Pyrococcus horikoshii OT3 A proposed structure of the regulatory subcomplex of eukaryotic IF2B. Biochem. Biophys. Res. Commun. 319, 725—732. 

The seven-vertex rV/o-phosphadicarbaborane [ / >-6-R -3,4-R2-6,3,4-PC2B4H4] (R = Et, Bz R = Ph, /Bu, Me) 26 was prepared by salt eliminaton reaction between the dianion [ fr/0-2,3-R2C2B4H4]2 anc RTCI2. The proposed structure of the OTdo-phosphacarborane framework based upon NMR spectroscopical findings was confirmed by quantum mechanical calculations.124... 

The 1H NMR spectra were all in good agreement with the proposed structures of the polymers in Figure 7. 

Fig. 6. Proposed structure of the cytochrome c ccp complex based on the model of Poulos and Kraut...

Cram and co-workers have experimented extensively with chiral recognition in crown ethers derived from various 3-binaphthols (73). In nonpolar solvents, these chiral ethers complex salts of PEA and various chiral a-amino esters (with fast exchange), inducing nonequivalence in their NMR spectra. The senses of proton nonequivalence induced in these solutes have been used to support proposed structures of the diastereomeric solvates (74). 

Structural models, which are synthesized to imitate features of the proposed structure of the active site. These may be used to demonstrate the chemical conditions, which allow such structures to exist, to investigate their chemical properties and to give a better understanding of the spectroscopic characteristics of the native proteins. Examples of these include the mixed carbonyl/cyano complexes of iron, used to verify the infrared spectra to the hydrogenases (Fig 7.4) (Lai et al. 1998) and the nickel-thiolate complexes which have low redox potentials like the hydrogenases (Franolic et al. 1992). 

Scheme 10.1 Syntheses and proposed structures of the supported Ru complex 3 and the unsaturated active complexes 4 and 5 on SI02, following exoergonic (energy-gaining) routes, together with bond lengths determined by XRD (for ligands) and EXAFS (for Oy)...

A soluble prepolymer results from the addition of bismaleimidodiphenyl methane 1 to diallyl bisphenol A 2 at approximately 150 °C. In the present study, a detailed 13C NMR investigation has provided strong evidence for the proposed structure of the soluble olig< ier. The NMR has also provided s< >e idea of the rate of... 

The proposed structure of the complex does not assume a static distribution of the sequences. The system is of course a dynamic one, but we study it at equilibrium. A given COOH group, involved in a complex at the moment t, may be free or in the carboxylate from at t + dt. However the average number of complexed sequences remains invariant with time for a fixed composition of the system. The situation can be compared with the behaviour of macromolecules adsorbed at a solid-liquid interface their mean conformation is stable even if locally an adsorption/desorption equilibrium occurs. 

Stannous chloride reduction of the cilcoholysis products led to the chelate complex PtBrs (oS). A reaction scheme and the proposed structures of the compounds PtBrs (oSX)—(oS) (X = Br, OMe, OEt, 0"Pr, 0 Bu) are shown in Fig. 8. The structure of the ethoxy derivative has been confirmed by X-ray diffraction analysis 13). 

Fig. 18.8 Proposed structures of the oxide film formed on iron at 350 °C (Seo et al., 1975, modified, with permission).

Scheme 3.1-1. Proposed structure of the overall system Homogeneous Catalysis ...

Spontaneous polymerization of 4-vinyl pyridine in the presence of polyacids was one of the earliest cases of template polymerization studied. Vinyl pyridine polymerizes without an additional initiator in the presence of both low molecular weight acids and polyacids such as poly(acrylic acid), poly(methacrylic acid), polyCvinyl phosphonic acid), or poly(styrene sulfonic acid). The polyacids, in comparison with low molecular weight acids, support much higher initial rates of polymerization and lead to different kinetic equations. The authors suggested that the reaction was initiated by zwitterions. The chain reaction mechanism includes anion addition to activated double bonds of quaternary salt molecules of 4-vinylpyridine, then propagation in the activated center, and termination of the growing center by protonization. The proposed structure of the product, obtained in the case of poly(acrylic acid), used as a template is ... 

Figure 4.1-3 Proposed structure of the asymmetric [HCl2] ion bound to the [EMIM]" cation in a binary mixture of HCI/[EMIM]CI. The figure has been redrawn from reference 10 with permission.

Figure 27. Tetrakisl4, 5 -bis(decoxy)ben20-18-crown-61phthalocyanine 22. Proposed structure of the crystalline phase (a) view along the normal on the Pc xy-plane and (b) view along the molecular x-axis. (c) Multiwired molecular cable self-assembled in chloroform solution.

Figure 4. Comparison of nicandrenone structure (top) to the proposed structure of the feeding stimulant (bottom). R = glycosyl.

Fig. 10. CPK model of the proposed structure of the complex of 11 with an alkali metal ion ( clamshell complex ). (Reproduced with permission from the American Chemical Society)...

Addition of an alkali metal ion to 23 should also make this host molecule a better binder of aromatic guest molecules. In the aa conformation unlike the as conformation-the 7r-electron rich naphthalene walls are capable of sandwiching rc-electron poor molecules (see Fig. 12). Indeed, upon addition of a potassium salt to a solution of 23, the for binding of 1,3-dinitrobenzene increases by a factor of 2 to 6, depending on the solvent systems [26]. Consistent with the proposed structure of the complex of 23 with sodium ions, addition of these ions has no effect on the of 23 with 1,3-dinitrobenzene. 

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