Carboxylate salt bridge interaction

We found 192 unique structures, with 252 recorded activities on 46 targets (see also Figure 2.3). A vast majority of them (176 structures) are likely to be charged at pH 7.4, as they are aliphatic amines, amidines or guanidines, and sometimes carboxylic acids. This indicates that low MW compounds are likely to require salt bridge interactions... 

A more pronounced role of the proton in the photoinduced PCET event can be imposed in model systems that contain a hydrogen bond interface composed of Dp and Ap pairs possessing pK s that can support the transfer of a proton. We have designed PCET networks assembled from asymmetric amidinium-carboxyl-ate salt bridges. In the solid state, the amidinium-carboxylate interface is ionic in nature and combines the dipole of an electrostatic ion-pair interaction within a hydrogen bonding network [108, 109]. The amidinium-carboxylate salt bridge in-... 

Otsuki et al. [27] have demonstrated that amidinium-carboxylate salt bridges, which have been used earlier to construct electron donor-acceptor dyads or a donor-spacer-acceptor triad, can also be used to assemble energy donor-acceptor dyad 13 and pentad 14. The salt bridge consists of complementary double hyi-ogen bonds and electrostatic interactions and, therefore, offers... 

Figure 9. A salt-bridge interaction is responsible for the dimeric structure 9 formed between a porphyrin bearing a carboxylate group and a protonated sapphyrin.

EIectrosta.tlcs. Electrostatic interactions, such as salt bridges, result from the electrostatic attraction that occurs between oppositely charged molecules. These usually involve a single cation, eg, the side chain of Lys or Arg, or the amino terminus, etc, interacting with a single anion, eg, the side chain of Glu or Asp, or the carboxyl terminus, etc. This attractive force is iaversely proportional to the distance between the charges and the dielectric constant of the solvent, as described by Coulomb s law. 

While loops lack apparent stmcmral regularity, they exist in a specific conformation stabilized through hydrogen bonding, salt bridges, and hydrophobic interactions with other portions of the protein. However, not all portions of proteins are necessarily ordered. Proteins may contain disordered regions, often at the extreme amino or carboxyl terminal, characterized by high conformational flexibility. In many instances, these disor-... 

The (E)-alkene (74) is formed from Wittig reaction of the corresponding phenyl 3-pyridyl ketone the stereochemical preference is determined by an interaction (either hydrogen bonding or salt bridging) between the carboxylic acid chain being introduced and the amide tether provided by the reactant." ... 

The observed ellipticities below 250 nm are characteristic of an a-helix and different from a 310-helix, according to the distinction described by Toniolo et alJ131 The CD spectrum indicates that two turns of a helix can be readily detected by this measure, in contrast to previous expectations.[132,133] The molar ellipticity shows no temperature dependence. It is, however, affected by pH as protonation of the template carboxylate and the Glu side chain leads to loss of the favorable dipole interactions and salt bridges, respectively. 

Electrostatic forces these include the interactions between two ionic groups of opposite charge, for example the ammonium group of Lys and the carboxyl group of Asp, often referred to as an ion pair or salt bridge. In addition, the noncovalent associations between electrically neutral molecules, collectively referred to as van der Waals forces, arise from electrostatic interactions between permanent and/or induced dipoles, such as the carbonyl group in peptide bonds. 

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