Proton occupancies

Fig. 1.2. Correlation between proton occupancies in the kinetic burst phase intermediate (black circles) and average area buried upon folding (AABUF, gray lines) for wild-type apomyoglobin and for a quadruple mutant (LeullGly, Trpl4Gly, Ala71Leu, Gly73Trp - termed the GGLW mutant). Reproduced with permission from [10]...

In the faujasite framework there are also four crystallographically distinct oxygens. The experimental proton occupation in H-faujasite is 8 2 4 for the... 

The same proton occupation in each unit cell occurs in phase IV. Hence the change in symmetry of the proton distribution in phase IV, in comparison with phase II, may be formally connected with one of irreducible representations of group Gk=o, if only the proton subsystem is taken into account. 

The temperature dependence of the different phonon-activated transfer processes is defined by the redistribution of proton occupancies hj of three sublattices (/ 1.2.3). For example, in the web-superionic phase the... 

In Figure 4, the proton occupancies measured at the end of the fast phase... 

Figure 4. NH exchange labeling pattern observed in pulse tobeling experiments at tj = 30 ms (c.f. Fig. 2) coded into the native cyt c structure. The shading reflects the proton occupancies for 35 NH sites determined by 2D NMR as described in the text...

Figured. Pulse-pH profiles measured by pulse labeling at variable labeling pH after a refolding time of 30 ms. Proton occupancies measured by ID NMR are shown for representative amide sites in the three main a-helices of cyt c.

Unless proton occupancy of exchange sites is taken into account, hydrolytic exchange will seem to create nonstoichiometric exchange between cations. An example is shown in Figure 3.15, where the adsorption of on a Na -smectite appears to release more Na into solution than mole-for-mole exchange could produce. 

The pK of a compound is thus a description of the tendency of a compound to donate its titratable proton. A plot of the fractional proton occupancy of an acid or a base versus pH is called a titration curve and has the familiar sigmoid shape typical of binding reactions. 

Some ND data were then collected by Denne and Jones, and used in an attempt to study proton occupancy at various possible sites by least-square... 

At a sufficiently high temperature, provided the oxyhydroxide is still stable, the ordered protons may disorder fully. This is then a phase transformation into a phase of partial proton occupancy on oxide ions. In Ba4(Ca2Nb2)Oio(OH)2 we may have, for instance, O + H sites with real charge of-11/6 as perfect. A... 

---