Rearrangements conformation

Borovinskiy, A.L., Grosberg, A.Y. Design of toy proteins capable of rearranging conformations in a mechanical fashion. J. Chem. Phys. 2003, 118, 5201-12. 

Let us examine the stereochemistry of pinacolic deamination in some detail.. In this we shall see the operation of a factor we have not yet encountered in rearrangements conformational effects. More important, we shall get some idea of the methods used to attack problems like this. 

The study of nonrigid systems has closely followed the technical advance of NMR instrumentation. In the last 5 years, the rapid advances in C spectroscopy have made previously undetectable carbonyl rearrangements, conformational interconversions, and fluxionality accessible. Carbonyl rearrangements will be reviewed by J. Takats in a future volume of this series major developments in the understanding of noiuigidity in 7r-complexes are discussed here. 

Conformations and Dynamic Situations.—Rotation about single bonds " and partial double bonds, carbonium-ion rearrangements, conformational processes in rings, and spin-lattice relaxation times and the mobility of organic molecules in solution have been reviewed. The proton spin-lattice relaxation of polycrystalline bicyclo[2,2,2]oct-2-ene has been measured and the enthalpy of activation or reorientational motion calculated. 

Large annulenes tend to undergo conformational distortion, cis-trans isomerizations, and sig-matropic rearrangements (p. 40 and p. 100). Methylene-bridged conjugated (4n + 2)-ic cyclopolyenes were synthesized with the expectation that these almost planar annulenes should represent stable HOckel arenes (E, Vogel, 1970, 1975). 

Schmidt reaction of ketones, 7, 530 from thienylnitrenes, 4, 820 tautomers, 7, 492 thermal reactions, 7, 503 transition metal complexes reactivity, 7, 28 tungsten complexes, 7, 523 UV spectra, 7, 501 X-ray analysis, 7, 494 1 H-Azepines conformation, 7, 492 cycloaddition reactions, 7, 520, 522 dimerization, 7, 508 H NMR, 7, 495 isomerization, 7, 519 metal complexes, 7, 512 photoaddition reactions with oxygen, 7, 523 protonation, 7, 509 ring contractions, 7, 506 sigmatropic rearrangements, 7, 506 stability, 7, 492 N-substituted mass spectra, 7, 501 rearrangements, 7, 504 synthesis, 7, 536-537... 

H -Azepin-2-one, 4-allyloxytetrahydro-Claisen rearrangement, 7, 508 1 H-Azepin-2-one, hexahydro-conformation analysis, 7, 499 mass spectra, 7, 501... 

Beckmann rearrangement, 4, 292 phototransposition, 4, 204 synthesis, 4, 223 Wittig reaetion, 4, 294 Wolff-Kishner reduetion, 4, 291 Pyrrole, 1-aeyl-barrier to rotation, 4, 193 IR speetra, 4, 21, 181 rearrangement, 4, 41 synthesis, 4, 82 thermal rearrangement, 4, 202 Pyrrole, 2-aeyl-aeidity, 4, 297 cleavage, 4, 289 conformation, 4, 33... 

Thiazoline-2-thione, 3-amino-pharmacological properties, 6, 328 4-Thiazoline-2-thione, 5-amino-Cook s rearrangement, 6, 290 4-Thiazoline-2-thione, 4-/-butyl-3-methyl-rearrangement, 6, 291 4-Thiazoline-2-thione, 3,4-dialkyl-conformation, 6, 247 4-Thiazoline-2-thione, 4,5-dimethyl-reactions... 

The basic chemical description of rare events can be written in terms of a set of phenomenological equations of motion for the time dependence of the populations of the reactant and product species [6-9]. Suppose that we are interested in the dynamics of a conformational rearrangement in a small peptide. The concentration of reactant states at time t is N-n(t), and the concentration of product states is N-pU). We assume that we can define the reactants and products as distinct macrostates that are separated by a transition state dividing surface. The transition state surface is typically the location of a significant energy barrier (see Fig. 1). 

In free CDK2 the active site cleft is blocked by the T-loop and Thr 160 is buried (Figure 6.20a). Substrates cannot bind and Thr 160 cannot be phosphorylated consequently free CDK2 is inactive. The conformational changes induced by cyclin A binding not only expose the active site cleft so that ATP and protein substrates can bind but also rearrange essential active site residues to make the enzyme catalytically competent (Figure 6.20b). In addition Thr... 

Figure 13.10 Rearrangements of the hydrogen bond network between strands 1, 2, and 3 in the p sheet of Go. as a consequence of the switch from the GDP (blue) to the GTP (green) conformation. Strand P3 pulls away from pi and disrupts two hydrogen bonds in order to bring Gly 199 into contact with the y-phosphate of GTP. As a consequence new hydrogen bonds are formed between P2 and P3. (Adapted from D. Lambright et al.. Nature 369 621-628,...

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