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Dihedral angle

About: Dihedral angle is a research topic. Over the lifetime, 15718 publications have been published within this topic receiving 174904 citations.


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TL;DR: In this article, the sintering kinetics of two touching circular particles are investigated as a function of the dihedral angle at the grain boundary-surface junctions and grain boundary to surface diffusivity ratio.
Abstract: We investigate the sintering of two touching circular particles by surface and grain boundary diffusion. Typical examples for the evolution of the shape of the particles, their surface curvatures, and their surface fluxes are given. The sintering kinetics are evaluated as a function of the dihedral angle at the grain boundary-surface junctions and the grain boundary to surface diffusivity ratio. In particular, the growth rates of the neck between the two particles, the growth rate exponents, and the changes in the lengths of the particle pairs are monitored. The times needed to reach certain fractions of the final equilibrium neck sizes are tabulated for typical experimental dihedral angles and diffusivity ratios. Our simulation is based on a rigorous mathematical system modeling the sintering of the two particles, and a rigorous numerical method for solving this system is adopted.

114 citations

Journal ArticleDOI
TL;DR: The constrained nature of the vicinal disulfide turn and the pronounced difference observed between the oxidized and reduced states, suggests that vicinaldisulfides may be employed as a 'redox-activated' conformational switch.
Abstract: The formation of a disulfide bond between adjacent cysteine residues is accompanied by the formation of a tight turn of the protein backbone. In nearly 90% of the structures analyzed a type VIII turn was found. The peptide bond between the two cysteines is in a distorted trans conformation, the omega torsion angle ranges from 159 to -133degrees, with an average value of 171degrees. The constrained nature of the vicinal disulfide turn and the pronounced difference observed between the oxidized and reduced states, suggests that vicinal disulfides may be employed as a 'redox-activated' conformational switch.

114 citations

Journal ArticleDOI
TL;DR: The atomic coordinates resulting from the present structure refinement are important data for understanding the structures of EGF-like proteins and for further detailed comparisons of these structures with mEGF.
Abstract: The solution structure of murine epidermal growth factor (mEGF) at pH 3.1 and a temperature of 28 degrees C has been determined from NMR data, using distance geometry calculations and restrained energy minimization. The structure determination is based on 730 conformational constraints derived from NMR data, including 644 NOE-derived upper bound distance constraints, constraints on the ranges of 32 dihedral angles based on measurements of vicinal coupling constants, and 54 upper and lower bound constraints associated with nine hydrogen bonds and the three disulfide bonds. The distance geometry interpretation of the NMR data is based on previously published sequence-specific 1H resonance assignments [Montelione et al. (1988) Biochemistry 27, 2235-2243], supplemented here with individual assignments for some side-chain amide, methylene, and isopropyl methyl protons. The molecular architecture of mEGF is the same as that described previously [Montelione et al. (1987) Proc. Natl. Acad. Sci. U.S.A. 84, 5226-5230], but the structure is overall more precisely determined by a more extensive set of NMR constraints. Analysis of proton NMR line widths, amide proton exchange rates, and side-chain 3J(H alpha-H beta) coupling constants provides evidence for internal motion in several regions of the mEGF molecule. Because mEGF is one member of a large family of homologous growth factors and protein domains for which X-ray crystal structures are not yet available, the atomic coordinates resulting from the present structure refinement (which we have deposited in the Brookhaven Protein Data Bank) are important data for understanding the structures of EGF-like proteins and for further detailed comparisons of these structures with mEGF.

113 citations

Journal ArticleDOI
TL;DR: The crystal and molecular structure of quercetin, one of the bioflavonoids found in plants, is described in this article, and the structure is of interest because of the variety of biological systems affected by it.

112 citations

Journal ArticleDOI
TL;DR: Although a large effect was found, the observed rotations are a factor of 2.6 smaller than the calculated values, independent of both conformation and wavelength from 589 to 365 nm.
Abstract: The specific rotations of 2-substituted butanes (X = F, Cl, CN, and HCC) were calculated at the B3LYP/aug-cc-pVDZ level as a function of the C−C−C−C torsion angle. The results for the four compounds are remarkably similar, despite large differences in the electronic transition energies. The temperature dependence of the specific rotations for 2-methylbutyronitrile and for 2-chlorobutane was studied to give experimental information about the effect of the torsion angle on the specific rotation. The results were in good accord with B3LYP/aug-cc-pVDZ calculations. The specific rotations derived from the study of 2-chlorobutane are similar to those previously obtained for 3-chloro-1-butene, indicating that the double bond does not have a large effect on the optical rotations, but it did lead to a large difference between calculated and observed specific rotations.

111 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023203
2022473
2021160
2020195
2019193
2018216