Charge pairing

Two other atomic properties have been used in the definition of atom type, thereby increasing its fuzziness relative to that in the ap and tt descriptors - atomic log P contribution (yielding hydrophobic pairs, hps, and torsions, hts) and partial atomic charges (charge pairs, cps, and charge torsions, cts). 

The surfaces that form subunit-subunit contacts are very much like parts of a protein interior detailed fit of generally hydrophobic side chains, occasional charge pairing, and both side chain and backbone hydrogen bonds. Twofold symmetry is the most common relationship between subunits. The 2-fold is often exact and can be part of the actual crystallographic symmetry, as for the prealbumin dimer in Fig. 62. However, in many cases (e.g., Tulinsky et al., 1973 Blundell et al., 1972) individual side chains very close to the approximate 2-fold axis must take up nonequivalent positions in order to avoid overlapping (see Fig. 63). Conformational nonequivalence can extend further away from the axis and produce such effects as different... 

Penmans P, Forrest SR (2004) Separation of geminate charge-pairs at donor-acceptor interfaces in disordered solids. Chem Phys Lett 398 27... 

For this reason (and others), it is not trivial to make a solid-state version of the dye cell. Initial attempts did not include a mobile electrolyte and thus had no way of neutralizing the Coulomb attraction between the photogenerated charge pairs [42,53]. The best results were achieved by Tennakone et al. [13] in a cell with solid Cul as the hole conductor—in which the ionic mobility of the Cul may have helped neutralize the Coulomb attraction. Later attempts included mobile electrolyte ions, which improved performance [9,54]. 

If both L ro and l ro, the Arrhenius law takes place with the effective activation energy E equal to that of the Coulomb attraction just after the creation of charged pair, similar to the case of elastic interaction. Note that since the actual value of the Onsager radius L in alkali halides could be as large as L 100 A (T = 100 K, e 5, — —ee = e), only a small... 

Many detectors have been developed to collect and amplify the primary ionization created by nuclear particles. In principle, the careful measurement of this ionization provides the most information about the particle and its energy. The devices with the highest resolution are these detectors based upon ionization. Broadly speaking, ionization-based detectors have the common feature that the incident radiation creates ion pahs in an active volume of the device. An electric field is applied to the active volume to separate the charge pairs and sweep the ions to the electrodes. 

Strittmatter, P., Kittler, J.M., Coghill, J.E. Ozols, J. (1992). Characterization of lysyl residues of NADH-cytochrome 65 reductase implicated in charge-pairing with active-site carboxyl residues of cytochrome 65 by site-directed mutagenesis of an expression vector for the flavoprotein. Journal of Biological Chemistry 267, 2519-23. 

Three lysine-containing sequences in Cb5R have been shown to interact with carboxyl-containing sequences from cytochrome 65 (Strittmatter et al., 1992). One of these charge-pairs, which is Glu581-Lys647 in the tobacco sequence (Fig. 3), is conserved in NRs. 

Kramer, R. Z., Venugopal, M. G., Bella, J., Mayville, P., Brodsky, B., and Berman, H. M. (2000). Staggered molecular packing in crystals of a collagen-like peptide with a single charged pair./. Mol. Biol. 301, 1191-1205. 

Paired charges Paired charges such as salt bridges are much rarer than hydro-phobic interactions but do contribute about 12-14 kj mol-1 to stabilization of a protein. 

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