Retinal analogs with locked 6-7 conformations show that bacteriorhodopsin requires the 6-s-trans conformation of the chromophore

1986 ◽  
Vol 108 (20) ◽  
pp. 6410-6411 ◽  
Author(s):  
R. Van der Steen ◽  
P. L. Biesheuvel ◽  
R. A. Mathies ◽  
J. Lugtenburg
Keyword(s):  
Trans Conformation ◽  
Retinal Analogs

Rotational Spectra of Bicyclic Decanes: The Trans Conformation of (−)-Lupinine

2013 ◽  
Vol 117 (50) ◽  
pp. 13673-13679 ◽  
Author(s):  
Michaela K. Jahn ◽  
David Dewald ◽  
Montserrat Vallejo-López ◽  
Emilio J. Cocinero ◽  
Alberto Lesarri ◽  
...  
Keyword(s):  
Trans Conformation ◽  
Rotational Spectra

scholarly journals A Novel Trans Conformation of Ligand-Free Calmodulin

PLoS ONE ◽  
2013 ◽  
Vol 8 (1) ◽  
pp. e54834 ◽  
Author(s):  
Veerendra Kumar ◽  
Vishnu Priyanka Reddy Chichili ◽  
Xuhua Tang ◽  
J. Sivaraman
Keyword(s):  
Trans Conformation ◽  
Ligand Free

In situ Raman Spectroscopic Observation of Polymer Chains in Semi-Crystalline Polyethylene Solids

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Yusuke Hiejima ◽  
Takumitsu Kida ◽  
Koh-hei Nitta
Keyword(s):  
Conformational Changes ◽  
Tensile Elongation ◽  
Spectroscopic Observation ◽  
Polymer Chains ◽  
Trans Conformation ◽  
Raman Spectroscopic ◽  
Higher Temperature ◽  
Microscopic Origin ◽  
Crystalline Polyethylene

AbstractIn situ Raman spectroscopy is applied for polyethylene solid under various environments to elucidate the morphological and conformational changes. The trans conformation retains up to higher temperature for high-density polyethylene, reflecting higher stability of the orthorhombic crystals composed of stacked trans chains. It is suggested that the conversion of the non-crystalline trans chains to the crystalline phase is the microscopic origin of thermal history in the crystallinity, whereas the transformation between the trans and gauche conformers is practically in thermal equilibrium. Microscopic and dynamic mechanism of deformation during uniaxial stretching is investigated for the molecular orientation and the microscopic load sharing on the crystalline and amorphous chains. Lower crystallinity results in smoother and higher orientation toward the stretching direction, as well as higher load on the amorphous chains, during tensile elongation.

The methylenic sequence conformation in a series of isoelectronic molecules

1988 ◽  
Vol 66 (2) ◽  
pp. 341-347 ◽  
Author(s):  
Suzanne Deguire ◽  
François Brisse
Keyword(s):  
Solid State Nmr ◽  
Weighted Least Squares ◽  
Direct Methods ◽  
Aromatic Polyamide ◽  
Amide Group ◽  
Trans Conformation ◽  
A Value ◽  
Isoelectronic Series ◽  
Isoelectronic Molecules ◽  
Related Compounds

The crystal structures of 1,4-dibenzoylbutane, 2DBC, and ethyleneglycol dithiobenzoate, 2DBS, have been solved by direct methods in order to follow the evolution of the geometry and the conformation of the Y—CH2—CH2—Y sequence in the isoelectronic series of C6H5—CO—Y—CH2—CH2—Y—CO—C6H5 where Y = CH2, NH, O, and S. 2DBC is monoclinic, a = 7.750(4), b = 21.287(6), c = 8.905(2) Å, β = 100.55(3)°, Z = 4. 2DBS is also monoclinic, with a = 5.702(3), b = 16.171(15), c = 8.001(4) Å, β = 98.79(4)°, and Z = 2. Both compounds belong to the P21/n space group. The weighted least-squares refinements converged to Rw = 0.049 (2DBC) and 0.043 (2DBS). The conformation of the methylenic sequence is all-trans (2DBC) and g+tg− for 2DBS (t = trans, g = gauche). The ir spectra have absorptions at 1467, 1308, and 931 cm−1 (2DBC) and at 1408, 1239, and 727 cm−1 (2DBS), respectively, characteristic of the trans conformation of the Y—CH2—CH2—Y sequence. The 13C CP/MAS solid-state nmr spectra of these and other related compounds have been recorded. It is, in turn, possible to propose that the τ torsion angle between the amide group and the methylenic sequence, has a value of 85° in the aromatic polyamide, Nylon 2T.

Dipole moments, Kerr constants and solution-state conformations of di(pyridin-4-yl), di(pyridin-3-yl) and di(pyridin-2-yl) ketone

1980 ◽  
Vol 33 (12) ◽  
pp. 2597 ◽  
Author(s):  
PH Gore ◽  
IG John ◽  
RK Pierens ◽  
GLD Ritchie
Keyword(s):  
Carbon Tetrachloride ◽  
Dipole Moments ◽  
Strong Preference ◽  
Trans Conformation ◽  
Solution State ◽  
Kerr Constants

Experimental dipole moments and molar Kerr constants are reported and analysed for di(pyridin-4-yl), di(pyridin-3-yl) and di(pyridin-2-yl) ketone as solutes in carbon tetrachloride or cyclohexane at 298 K. The preferred conformation of di(pyridin-4-yl) ketone is found to be very similar to those previously deduced for benzophenone and several 4,4'- disubstituted benzophenones. For di(pyridin-3-yl) and di(pyridin-2-yl) ketone three analogous conrotatory structures having different relative dispositions of the nitrogen atoms are considered. In the case of di(pyridin-3-yl) ketone the cis-trans and trans-trans arrangements are approximately equally abundant, but for di(pyridin-2-yl) ketone there is a strong preference for the trans-trans conformation.

Etude conformationnelle par résonance magnétique nucléaire du carbone 13 de peptides à activité antalgique

1980 ◽  
Vol 58 (11) ◽  
pp. 1241-1246 ◽  
Author(s):  
Robert René Smolders ◽  
Roland Coomans ◽  
Françoise Jacquemotte ◽  
Yves Van Haverbeke ◽  
André Maquestiau ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Trans Conformation ◽  
Magnetic Resonance Studies ◽  
Ph Values ◽  
Résonance Magnétique ◽  
Nuclear Magnetic

13C Nuclear magnetic resonance studies of proline peptides with central antalgic activity (Pro-Arg, Arg-Pro, Pro-Arg-Pro, Pro-Lys-Pro) indicate a predominance of trans conformation at all pH values; but their physiological activities appear to be related to the ability of the C-terminal proline peptides to assume the cis conformation.

Darstellung und Kristallstruktur des Bis(diisobutylammonium)-heptasulfids [H2N(i-C4H9)2]2S7 / Synthesis and Crystal Structure of Bis(diisobutylammonium)-heptasulfide [H2N(i-C4H9)2]2S7

1993 ◽  
Vol 48 (12) ◽  
pp. 1732-1736 ◽  
Author(s):  
C. Müller ◽  
P. Böttcher
Keyword(s):  
Crystal Structure ◽  
Orthorhombic Space Group ◽  
Trans Conformation ◽  
Torsion Angles ◽  
Synthesis And Crystal Structure ◽  
Space Group ◽  
Lattice Constants ◽  
Ethanol Yields ◽  
The Common

The reaction of diisobutylamine, H2S, and sulfur in a mixture of dimethylformamide, formamide, and ethanol yields orange crystals of bis(diisobutylammonium)-heptasulfide. The compound crystallizes in the centrosymmetric orthorhombic space group Pbca, the lattice constants are a = 11.234(4), b = 17.875(7), c = 27.009(10) Å. The S72-chain does not have the common helical all-trans-conformation, but a mixed conformation trans-cis-trans (sequence of the signs of torsion angles + + - - and - - + +).

Relaxor Properties and Tunability of Electron-Irradiated Thin Poly(vinlidene fluoride-trifluoroethylene) Copolymer Film

2012 ◽  
Vol 560-561 ◽  
pp. 892-898 ◽  
Author(s):  
Li Tian ◽  
Xiang Jian Meng ◽  
Jing Yang ◽  
Jing Lan Sun ◽  
Sheng Zhao Yuan ◽  
...  
Keyword(s):  
Electron Irradiation ◽  
Dielectric Spectroscopy ◽  
High Energy ◽  
Copolymer Film ◽  
Relaxor Behavior ◽  
High Energy Electron ◽  
X Ray Diffraction ◽  
Gauche Conformation ◽  
Trans Conformation ◽  
X Ray

The effect of high energy electron irradiation on poly(vinlidene fluoride-trifluoroethylene) copolymer film with thickness about 180 nm has been studied. Both dielectric spectroscopy investigation and X-Ray Diffraction show that all-trans conformation of pre-irradiated films is transformed to trans-gauche conformation after irradiation. The relaxor behavior of irradiated sample obeys the modified Curie-Weiss and Vogel-Fulcher law. And the tunability is increased from 42% to 63% after irradiation.

scholarly journals Relative Rates of Bond Rotation and Ring Closure in the Photocycloaddition Intermediates from Fullerene-C60 and the Isomeric 2,4-Hexadienes

2019 ◽  
Author(s):  
Wendell Dilling
Keyword(s):  
Relative Rate ◽  
Product Distribution ◽  
Fullerene C60 ◽  
Ring Closure ◽  
Trans Conformation ◽  
Bond Rotation ◽  
Product Distributions

<p>Photocycloaddition of fullerene-C<sub>60 </sub>to the isomeric 2,4-hexadienesreported by Orfanopoulos and co-workers gave a series of 2 + 2 cycloadducts in which bond rotation had occurred in some products. Relative rates of bond rotation and ring closure in the biradical intermediates were calculated from the product distributions using equations developed by Bartlett and co-workers. These data are reinterpreted to show that the ratio of the rate of bond rotation in the intermediate to the rate of ring closure to the cyclobutane product is ~70 for the <i>trans</i>-1-propenyl intermediate formed in the initial cis conformation. Data are inconsistent for the analogous <i>cis</i>-1-propenyl intermediate. The relative rate for the <i>trans</i>-1-propenyl intermediate formed in the initial trans conformation is ~9. Accurate relative rate determinations are highly dependent on very accurate product distribution determinations.</p>

scholarly journals Ab Initioand DFT Studies of Conformational Properties of Heteroatom Containing Ketene Analogues and Their Comparison with the Related Cyclic Analogues

2012 ◽  
Vol 9 (1) ◽  
pp. 193-202 ◽  
Author(s):  
S. Zahra Sayyed-Alangi ◽  
Mohammad T. Baei
Keyword(s):  
Transition State ◽  
Minimum Energy ◽  
Basis Set ◽  
Global Minima ◽  
Stable Conformer ◽  
Trans Conformation ◽  
Conformational Interconversion ◽  
Conformational Properties ◽  
Torsional Angles ◽  
Single Bonds

Minimum-energy and transition state geometries of 3-thioxoprop-2-enethial, 3-thioxoacrylaldehyde, 3-oxoprop-2-enethial, 3-selenoxoprop-2-enethial, 3-thioxoprop-2-eneselenal, 3-selenoxoprop-2-eneselenal, 3-oxoacrylaldehyde, 3-selenoxoacrylaldehyde and 3-oxoprop-2-eneselenal were calculated using HF, B3LYP and MP2 levels of theory and 6-31+G*basis set by rotation around the related -C-C- single bonds. In all of the above mentioned molecules, the s-trans conformation was obtained as the most stable conformer with the 180°dihedral angle, apart from 3-oxoprop-2-enethial and 3-thioxoprop-2-eneselenal which theirs-cisconformers were appeared more stability than related tos-transforms. Their perpendicular geometries, with torsional angles approximately 90°, were as transition state for conformational interconversion between the two global minima forms. Cyclic structures all of the above mentioned molecules were unstable than their linear forms.

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