Hydration conformation

Relation to Solubility D. Chou (is) noted that, for a random sampling of isolates, the viscosity was not necessarily correlated to the solubility. This is because many factors (conformation, hydration, exposure of hydrophobic groups, charge distribution, etc.) contribute to the intermolecular interactions that result in increased viscosity. However, within a series of similarly processed isolates or with a given isolate, we should expect the viscosity to be inversely... 

Simons JP, Jockusch RA, Carcabal P, Hung I, Kroemer RT, Macleod NA, Snoek LC (2005) Sugars in the gas phase. Spectroscopy, conformation, hydration, co-operativity and selectivity. Int Rev Phys Chem 24(3 ) 489-531... 

Mathematical Model of the Nucleic Acids Conformational Transitions with Hysteresis over Hydration-Dehydration Cycle... 

The hydration shell is formed with the increasing of the water content of the sample and the NA transforms from the unordered to A- and then to B form, in the case of DNA and DNA-like polynucleotides and salt concentrations similar to in vivo conditions. The reverse process, dehydration of NA, results in the reverse conformational transitions but they take place at the values of relative humidity (r.h.) less than the forward direction [12]. Thus, there is a conformational hysteresis over the hydration-dehydration loop. The adsorption isotherms of the NAs, i.e. the plots of the number of the adsorbed water molecules versus the r.h. of the sample at constant temperature, also demonstrate the hysteresis phenomena [13]. The hysteresis is i( producible and its value does not decrease for at least a week. 

Taking into account the hydration shell of the NA and the possibility of the water content changing we are forced to consider the water -I- nucleic acid as an open system. In the present study a phenomenological model taking into account the interdependence of hydration and the NA conformation transition processes is offered. In accordance with the algorithm described above we consider two types of the basic processes in the system and thus two time intervals the water adsorption and the conformational transitions of the NA, times of the conformational transitions being much more greater... 

The expressions for the changes in the free energy of the hydration shell of the NA (per NA units mole) in the U A and A— B conformational transitions should be written in the form ... 

In the United States most commercial hydrates easily conform to the minimum basic requirement of no more than 0.5% retained on 590 ]Am (30 mesh) screen and no more than 15% retained on a 74 ]Am (200 mesh) screen. Typical analyses of hydrates are contained in Table 5. 

In our last example we return to the issue of the possible damaging effects of the standard geometry constraints. Two long trajectories have been computed for a partially hydrated dodecamer DNA duplex of the previous example, first by using ICMD and second with Cartesian coordinate molecular dynamics without constraints [54]. Both trajectories started from the same initial conformation with RMSD of 2.6 A from the canonical B-DNA form. Figure 5 shows the time evolution of RMSD from the canonical A and B conformations. Each point in the figure corresponds to a 15 ps interval and shows an average RMSD value. We see that both trajectories approach the canonical B-DNA, while the RMSD... 

The nonchelated structure that conforms to the hydroxy tautomeric form of the ligand 248a has been found in the hydrate 379 [96JOM(511)227]. 

As mentioned above, water structure in reversed micelles deviates considerably from the structure in the bulk-phase. Therefore, the hydration shell of macromolecules entrapped in reversed micellar systems should be changed and thus also their conformation. According to the results of several authors this is indeed the case. 

Fig. 7. Besides direct interactions between functional groups of the biopolymer molecule itself there are also various kinds of interactions with water molecules. These hydrophilic and hydrophobic interactions are essential for stabilizing the native conformation of biopolymers. In the last few years some progress was made in elucidating the hydration of these molecules.

Furthermore it can be shown that besides the direct influence of hydrophilic and hydrophobic hydration on the conformation, the interaction of charged groups with ions is also strongly influenced by the hydration of the groups involved. Such studies were made largely by using relatively simple poly-a-aminoacids with ionogenic side chains as model substances. 

Fig. 12. Schematic representation of the a-helix-inducing effect of specific bound anions like CIO4 or SCN" in the case of N-co-trialkylaled BPAA the extended helical conformation contracts by the insertion of the anions. The water molecules of the hydration shells are omitted 1091...

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