Distances intramolecular

Intramolecular distances determined by fluorescence energy transfer... 

Intramolecular distances between functional sites of the Ca transfer... 

The intramolecular distances measured at room temperature with the AEDANS FITC pair were similar in the Ca2Ei and E2V states [297]. Ca and lanthanides are expected to stabilize the Ej conformation of the Ca -ATPase, since they induce a similar crystal form of Ca -ATPase [119,157] and have similar effects on the tryptophan fluorescence [151] and on the trypsin sensitivity of Ca -ATPase [119,120]. It is also likely that the vanadate-stabilized E2V state is similar to the p2 P state stabilized by Pi [418]. Therefore the absence of significant difference in the resonance energy transfer distances between the two states implies that the structural differences between the two conformations at sites recorded by currently available probes, fall within the considerable error of resonance energy transfer measurements. Even if these distances would vary by as much as 5 A the difference between the two conformations could not be established reliably. 

The TCNQ molecule in [TR(bzim)]2-TCNQ is sandwiched between two units of [ J,-N, C -bzimAu]3 in a face-to-face manner so that it is best represented by the formula (7t-[ J,-N, C -bzimAu]3)( j,-TCNQ)(7t-[p-N, C -bzimAu]3). The cyanide groups clearly are not coordinated to the gold atoms. The distance between the centroid of TCNQ to the centroid of the AU3 unit is 3.964 A. The packing of [TR(bzim)]2-TCNQ shows a stacked linear-chain structure with a repeat pattern of-(Au3)(Au3)(p-TCNQ) (Au3)(Au3)(p-TCNQ)- an ABBABB repeat The complex [TR(bzim)]2-TCNQ contains two very short intermolecular Au Au distances of 3.152 A (identical for the two aurophilic bonds). The intermolecular Au Au distance is even shorter than the intramolecular distances in the starting compound, which are 3.475, 3.471, and 3.534 A. The adjacent AU3 units in [TR(bzim)]2-TCNQ form a chair-type structure rather than the face-to-face (nearly eclipsed) pattern reported in Balch s studies of the nitro-9-fluorenones adducts with the trinuclear Au(I) alkyl-substituted carbeniate complexes. 

The form and shape of a molecule (i.e. its steric and geometric features) derive directly from the molecular genotype , but they cannot be observed without a probe. Furthermore, they vary with the conformational, ionization and tautomeric state of the compound. Thus, the computed molecular volume can vary by around 10% as a function of conformation. The same is true of the molecular surface area, whereas the key (i.e. pharmacophoric) intramolecular distances can vary much more. 

Inter-/intramolecular distances 0.1-1 nm Nuclear Overhauser effect (1-NMR), dipolar splittings (s-NMR)... 

Table 6 Calculated intramolecular distances R(X-Y) [A] of the XY- NH3 complexes as obtained with different methods applying the aug-cc-pVTZ basis set ...

We will confine ourselves to those applications concerned with chemical analysis, although the Raman microprobe also enables the stress and strain imposed in a sample to be examined. Externally applied stress-induced changes in intramolecular distances of the lattice structures are reflected in changes in the Raman spectrum, so that the technique may be used, for example, to study the local stresses and strains in polymer fibre and ceramic fibre composite materials. 

Although the structural formulae of 1 and 3 are very similar, their NOE behaviour is very different all the protons of 1 show an NOE The reasons for this become clear when we refer to the known X-ray crystal structures of 1 and 3. Although these depict a defined arrangement in the crystal, whereas NMR spectra reflect averages of possible arrangements in solution, the intramolecular distances measured from the crystal structures do in fact correlate well with the results from the NOE measurements, as is shown in Table 3 below. 

As discussed above, one obtains a large amount of structural information upon completion of the data analysis, which will be illustrated using the example of theophylline monohydrate [20]. Table 7.3 contains a summary of intramolecular distances involving the non-hydrogen atoms in the structure, while Table 7.4 shows the intramolecular... 

Intramolecular distances in theophylline monohydrate involving nonhydrogen atoms [20]... 

Measurement (constrained residue) Intramolecular distance Intermolecular effect... 

Controversial results are reported in the literature regarding the polydispersity of polyesters produced by SSP, associated with the side reactions in the later stages of the reaction. These are not only dependent on the concentrations of the reactive groups but also on their intramolecular distances [11], Additionally, it has been found that cyclization leads to a different polydispersity. According to theoretical considerations, the polydispersity index of an SSP polymer is generally higher than that of prepolymer produced in the melt phase, which should, in an ideal case have a value of 2 [21-24, 59],... 

According to Lonsdale et al., the four aromatic bridgehead atoms C8, Cg, Cu and C14 are bent out of the plane of the remaining benzene carbon atoms by about 0.168 A (14°) at 291 °K (see Fig. 1) the aromatic nuclei are deformed into a boat conformation. The distance between the aromatic bridgehead atoms C3, C14 and Cg, Cu has shrunk to 2.751 A. The intramolecular distance between the plane formed by atoms C4, C5, C7, Cg and that formed by atoms C12, C13, C15, Ci6 is only 3.087 A the van der Waals distance between two parallel benzene nuclei is usually at least 3.4 A. There must therefore be considerable transannular -overlapping in compound 2. To compensate for this the CH2-CH2 bond length is unusually large 1.630 A at 291 °K at 93°K it is only 1.558 A. 

A basic theoretical model for flexible polymers is the Gaussian chain which assumes N ideal beads with intramolecular distance between them following a Gaussian distribution, so that the mean quadratic distance between two beads separated by n-1 ideal and not correlated bonds is given by [ 15,20]... 

Ganazzoli et al. [53] performed calculations for the hydrodynamic radius (based on the Kirkwood formula), and also for the intrinsic viscosity [87] of uniform stars, using a generahzed version of the ZK method that incorporates non-Gaussian intramolecular distances. These distances were obtained according to... 

Fig. 14. Normalized averaged intramolecular distances plotted as a function of the position of bead j for a star with 12 arms with a total of 472 bonds. The beads are labeled as negative from -N to 0 (the central atom) on the first arm and as positive up to on the second arm. The three locations of the first bead i corresponds to i -N, at the free end of the first arm (circles) i=-N /2, at the midpoint of the first arm (squares) and i=0, at the central branch point (triangles). Reprinted with permission from [158]. Copyright (1997) American Chemical Society...

The scattering function can be expanded for low values of q. The expansion coefficients correspond to high moments involving summations of powers of different intramolecular distances (it is well known that the mean quadratic ra-... 

However, the consideration of intramolecular interactions and, therefore, of reahstic distributions of intramolecular distances changes the shape of the func-... 

Measurement of Intramolecular Distances in Peptides by Singlet-Singlet... 

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