Molecular self-association

Touitou, E., Alhaique, F., Fisher, P., Memoli, A., Riccieri, F. M., and Santucci, E., 1987, Prevention of molecular self-association by sodium salicylate Effect on insulin and 6-carboxfluorescein, J. Pharm. Sci. 76 791-793. 

A study of the effect of substitution patterns in oxadiazoles and isoxazoles and their effect on the UV spectra in the lO -lO M concentration range was performed. Hypso-chromic effects and deviations from Beer s law were observed and were believed to be associated with antiparallel, sandwich-type self-association via dipole-dipole interactions. Beer s law is followed when the molecular dipole moments are small or when self-association is sterically hindered. 

The polymeric products from disordered AG have much smaller molecular weights and reduced tendency to self-associate in solution. Such properties may be desirable in applications requiring membrane permeability. 

Coacervation occurs in tropoelastin solutions and is a precursor event in the assembly of elastin nanofibrils [42]. This phenomenon is thought to be mainly due to the interaction between hydro-phobic domains of tropoelastin. In scanning electron microscopy (SEM) picmres, nanofibril stmc-tures are visible in coacervate solutions of elastin-based peptides [37,43]. Indeed, Wright et al. [44] describe the self-association characteristics of multidomain proteins containing near-identical peptide repeat motifs. They suggest that this form of self-assembly occurs via specific intermolecular association, based on the repetition of identical or near-identical amino acid sequences. This specificity is consistent with the principle that ordered molecular assembhes are usually more stable than disordered ones, and with the idea that native-like interactions may be generally more favorable than nonnative ones in protein aggregates. 

An anthocyanin occurs in solution as a mixture of different secondary structures, a quinonoidal base, a carbinol pseudobase, and a chalcone pseudobase. ° hi addition, different mechanisms for the stabilization of anthocyanins lead to the formation of tertiary structures such as self-association, inter-, and intra-molecular co-pigmentation. ... 

In the case of the analytes able to participate in the self-associative lateral interactions (i.e., containing at least one AB functionality in their molecular structure), the negative impact of the interactions exerted on the separation performance depends on the number of the associated monomers per one H-bonded -meric unit, and the higher the number (n) of the self-associated analyte monomers in a given aggregate, the more crippled is the separation process. 

We Have studied data for one molecular association set, the self association of dlalkyl ketones, using the XB equation with the addition of a term in the number of C atoms (no) as a measure of polarizability. Thus,... 

One of the important aspect of the use of dihydrogen bonds as driving forces in molecular associations is their cooperativity or anticooperativity when increasing the number of H- H contacts in the self-association of molecular systems leads to additional energy, calculated on the basis of one dihydrogen bond, or vice versa. As we have shown in Chapter 2, classical hydrogen bonds can be highly cooperative, due to their mutual polarization [5]. 

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