Non-cooperative

Stereoelectronic effects and nonbonded interactions are non-cooperative in the reactions of (E)-allylboronates and x-heteroatom-substituted aldehydes. Thus, while transition state 8 experiences the fewest nonbonded interactions (gauche pentane type, to the extent that X has a lower steric requirement than R3), transition state 9 is expected to benefit from favorable stereoelectronic activation (Felkin-type)58f. This perhaps explains why the reaction of 2,3-[iso-propylidenebis(oxy)]propanal and ( >2-butenylboronate proceeds with a modest preference (55%) by way ol transition state 9. This result is probably a special case, how ever, since C-3 of 2.3-[isopropylidenebis(oxy)]propanal is not very stcrically demanding in 9 owing to the acetonide unit that ties back the oxygen substituent, thereby minimizing interactions with the... 

Usually non-cooperative and non-Unear binding isotherms were observed in alkaloid-B-DNA complexation and the data were fitted to a theoretical curve drawn according to the excluded site model [126] developed by McGhee and von Hippel [127] for a non-Unear non-cooperative ligand binding system using the following equation ... 

Hunter (60) reported a self-assembled open polymer formed by a zinc porphyrin bearing one para-aniline substituent at the meso position. The ortho- and mela-analogs discussed above form closed dimers, but the geometry of the para-derivative precludes this, and polymerization is the only alternative (76, Fig. 31). Although the dilution experiments could be fitted to a non-cooperative polymerization model with a pairwise association constant (K = 190 M 1) practically identical to that found for simple aniline-zinc porphyrin complexes (K = 130 M 1), broadening of the 4H NMR spectrum at high concentrations is characteristic of oligomerization. 

A slight increase in the turbidity upon heating of aqueous solutions of the s-fractions of the NVCl/NVIAz-copolymers obtained from the feeds with initial comonomer molar ratios of 75 25 (Tcp 65 °C) and 80 20 (Tcp 66 °C) could be due to the micellization phenomena, although the absence of DSC peaks over the same temperature range testified to the non-cooperative character of the process. This could indicate that the chains of these s-type copolymers had, nevertheless, a certain amount of oligoNVCl blocks non-buried by the hydrophilic microenvironment sufficiently well and thus capable of participating in the hydrophobically-induced associative intermolecular processes at elevated temperatures. At the same time, the sequence of monomer units in the s-copolymers obtained from the feeds with the initial comonomer ratios of 85 15 and 90 10 (mole/mole) corresponded to the block-copolymers of another type. The basis for such a conclusion is the lack of macroscopic heat-induced phase separation at elevated temperatures (Fig. 3 a and b) and, simultaneously, the transi-... 

Simultaneous rate equations are complex, but solvable. Simplifications are possible e. g. A l = 4 and 2 = 3 > if the sites are non-cooperative. Strong binding ligands such as edta or synthetic sidereophores effect iron removal and the two rate constants associated with the biphasic Fe removal are both curved towards saturation when plotted against [ligand]. 

Ma, K., and Wang, K. (2003). Malleable conformation of the elastic PEVK segment of titin Non-cooperative interconversion of polyproline II helix, beta-turn and unordered structures. Biochem.J. 374, 687-695. 

Where P( represents the stepwise stability constants and [L] is the concentration of Tree ligand. If the system is non-cooperative (i.e. Equation 1.26 holds true) then Equation 1.27 becomes Equation 1.28 ... 

Fig. 9. Calculated overall free energy of stabilization (AGtota ) for yeast phos-phoglycerate kinase at pH 6.5 and 0.7 M GuHCl. This curve displays two zeros, corresponding to the temperatures of cold and heat denaturation. Also shown in the curve are the cooperative Gibbs free energies (AG ) associated with the uncompensated exposure of apolar surfaces on unfolding of each of the domains. For both domains, AG is positive for the heat denaturation and close to zero for the cold denaturation. This behavior results in a cooperative heat denaturation and a non-cooperative cold denaturation. [Reprinted from Freire el al. (1991).]...

McGhee, J.D., and von Hippel, P.H. "Theoretical aspects of DNA-protein interactions cooperative and non-cooperative binding of large ligands to a one-dimensional homogeneous lattice". J. Mol. Biol. 86,469 89 (1974). 

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