Self-structured guanosine 5'-monophosphate. A carbon-13 and proton magnetic resonance study

Structural organization of guanosine derivatives in dilute solutions: small angle neutron scattering analysis

“…R and h are assumed according to previous X-ray diffraction results (Mariani et al 1989;Spada et al 1991) and to molecular dynamics calculations (Fisk et al 1982). Since the X-ray diffraction analysis of the hexagonal phase showed that the sectional radius is quite insensitive to the sample concentration (Mariani et al 1989;Spada et al 1991), we considered the value determined at C = 50% (Mariani et al 1989;Spada et al 1991).…”

“…Since the X-ray diffraction analysis of the hexagonal phase showed that the sectional radius is quite insensitive to the sample concentration (Mariani et al 1989;Spada et al 1991), we considered the value determined at C = 50% (Mariani et al 1989;Spada et al 1991). Computer simulations (Fisk et al 1982) showed that the coordination of the counterion to the phosphate may justify an increase of the tetrameric radius value up to 16 ~. Therefore, to overestimate the dimension of the model, we decided to consider 16/~ as a possible limit value.…”

“…where A is the distance between the piled disks, as determined in the hexagonal phase by X-ray diffraction experiments (Mariani et al 1989;Spada et al 1991) and the value 6.4 takes into account the hydration of the terminal disks (Fisk et al 1982).…”

The Self‐Recognition and Self‐Assembly of Folic Acid Salts in Isotropic Water Solution

“…This spectrum is characterized by intense cross-peaks of the same sign as the diagonal ones (negative NOE regime wz, > l), indicative of the existence of aggregated molecules. A series of measures were obtained for this solution using different mixingtime values (7,50,75,100,150,200,250, 300 ms) to identify the effects of anomalous enhancements due to spin diffusion by their non-exponential build-up. In this range of values, the build-up curve relative to the aromatic protons (H, and H,) is approximately linear until r, 250 ms. Analogous linear plots can be drawn for enhancements due to direct NOE linking the protons He with H, and H, or H, with H,.…”

Hydrogen Bonding

“…22 Likewise, 13 C relaxation has been used to estimate the size and shape of molecular complexes such as that in Figure 4. 23 Extensive use has been made of 1 H NMR relaxation to explore hydrogen bonding and hydrogen exchange processes, especially in water. Because of the proximity of protons in adjacent molecules, intermolecular dipolar relaxation must be considered equally with intramolecular relaxation.…”