An electron diffraction study of gaseous α-alanine, NH2CHCH3CO2H

Iijima, Kinya; Beagley, B.

doi:10.1016/0022-2860(91)85008-q

Cited by 76 publications

(43 citation statements)

References 22 publications

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“…Their lowest energy conformer is designated here as Gr-HF; (b) the studies of Császár (1995Császár ( , 1996, who compute the thirteen lowest conformational minima by HF-SCF and MP2 optimization with a 6-311++G * * basis set. The computed bondlengths, bond angles and torsion angles of the lowest energy conformer compare excellently with those determined experimentally by the gas-phase electron diffraction experiments of Iijima and Beagley (1991). Their lowest energy conformers are designated Cs-HF and Cs-MP2; (c) the studies of Stepanian (1998), who computes the five lowest energy conformational minima, optimized by DFT with a B3LYP functional and an aug-ccpVDZ basis set.…”

Section: No Problem In the Gas Phase!mentioning

confidence: 90%

Electroweak Parity-Violating Energy Shifts of Amino Acids: The “Conformation Problem”

MacDermott

Hyde

et al. 2009

Orig Life Evol Biosph

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The preceding paper described our coupled-perturbed Hartree-Fock (CPHF) and density functional theory (DFT) methods of computing the parity-violating energy shift (PVES). This paper addresses the "conformation problem"-the difficulty determining which hand of amino acids in solution is favoured by the weak force due to the difficulty determining the solution conformation. We attempt to resolve this by using the methods of the preceding paper to compute the PVES of solution and gas-phase amino acid structures determined by other groups from high level optimizations that include solvation. We conclude that the conformational hypersensitivity of the PVES still precludes a definite conclusion as to the sign of the PVES of L-alanine in solution, but that there is no problem in the gas phase: the PVES of gas-phase L-alanine is decisively negative. We show that the PVES is very sensitive to certain torsion angles, but is not hypersensitive to bondlengths or bond angles. In determining structures for PVES computations, there is therefore no need for expensive full optimizations: one can just optimize the crucial torsion angles. We present new computations of gas-phase amino acids PVESs, using partial optimizations with small basis sets, and the results agree well with those from higher level techniques. In the following paper we apply these less costly techniques to larger amino acids. The "conformation problem" has led some to dismiss the PVES as the source of life's handedness, but we believe this is premature: we show here that amino acids are a special case because their favoured conformations are almost achiral.

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Section: No Problem In the Gas Phase!mentioning

confidence: 90%

Electroweak Parity-Violating Energy Shifts of Amino Acids: The “Conformation Problem”

MacDermott

Hyde

et al. 2009

Orig Life Evol Biosph

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“…Its status of investigations is similar to the case of glycine. By means of electron diffraction 40 first structural information about alanine in one of its non-zwitterionic conformations was collected which could be verified theoretically on the MP2 23 and CCSD(T) level. 27,41 Calculations have been extended to additional conformers and different approximations for electron correlation in the molecular systems.…”

mentioning

confidence: 99%

DFT studies using supercells and projector‐augmented waves for structure, energetics, and dynamics of glycine, alanine, and cysteine

et al. 2007

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A large variety of gas phase conformations of the amino acids glycine, alanine, and cysteine is studied by numerically efficient semi-local gradient-corrected density functional theory calculations using a projector-augmented wave scheme and periodic boundary conditions. Equilibrium geometries, conformational energies, dipole moments, vibrational modes, and IR optical spectra are calculated from first principles. A comparison of our results with values obtained from quantum-chemistry methods with localized basis sets and nonlocal exchange-correlation functionals as well as with experimental data is made. For conformations containing strong intramolecular hydrogen bonds deviations in their energetic ordering occur, which are traced back to different treatments of spatial nonlocality in the exchange-correlation functional. However, even for these structures, the comparison of calculated and measured vibrational frequencies shows satisfying agreement.

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“…Values l X and r X were referred to those reported in the literature. 23,24 The calculated I X intra ðQÞ was then subtracted from the corrected Á X ðQÞ to deduce the intermolecular difference function, Á X inter ðQÞ:…”

mentioning

confidence: 99%

Structure of Highly Concentrated Aqueous Lithium Alaninate Solutions Studied by Neutron Diffraction with 14N/15N, 6Li/7Li, and H/D Isotopic Substitution Methods

Kameda

Sasaki

Amo

et al. 2006

Bulletin of the Chemical Society of Japan

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(1) , respectively.The structural properties of interactions between amino acid molecules and metal ions have received a lot of attention because of their importance in extensive fields of chemical and biological sciences. A large number of crystallographic data have been accumulated for various chelate complexes of amino acids with transition-metal ions, in which the amino acid molecule coordinates as a bidentate ligand binding through both amino-nitrogen and carboxyl-oxygen atoms.1 The complex formation of the glycinate ion with Ni 2þ , Cu 2þ , and Zn 2þ in aqueous solution has been investigated by X-ray diffraction 2-4 and EXAFS 5 methods. It has been reported that the coordination of these metal complexes is also accomplished as a bidentate chelate through the N and O atoms of the glycinate ion. An X-ray diffraction study on Zn(II) complexes with the -alaninate ion in aqueous solution has revealed that the alaninate ion exhibits bidentate coordination. 6 A relatively small number of structural investigations have reported on the interaction between alkali metal ions and amino acid molecules. According to a theoretical study on the gas-phase complexes of the glycine molecule with Li þ and Na þ , the lowest energy species corresponds to a five-membered ring in which Li þ and Na þ are coordinated to both N and O atoms of the glycine molecule. 7 On the other hand, recent single crystal X-ray diffraction results of sodium nitrate-glycine (1/1) have shown that the zwitterionic glycine molecule coordinates as a monodentate ligand to the sodium ion through a carboxyl-oxygen atom of the glycine molecule. 8 The coordination structure of amino acid with the alkali metal ion in aqueous solution has not yet been reported.In the present paper, we describe the results of TOF neutron diffraction measurements on aqueous 18 mol % lithium alaninate heavy water solutions.14 N/ 15 N, 6 Li/ 7 Li, H M /D M , and H M 0 /D M 0 isotopically substituted samples were employed in order to obtain information on the environmental structure around the substituted atom. Structural parameters concerning the first hydration shell of Li þ and those of the amino-nitrogen, the methyl-hydrogen, and the methine-hydrogen atoms of the alaninate ion were determined from the least squares fitting analyses of observed first-order difference functions, Á N ðQÞ, Á Li ðQÞ, Á HM ðQÞ, and Á H M 0 ðQÞ.

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An electron diffraction study of gaseous α-alanine, NH2CHCH3CO2H

Cited by 76 publications

References 22 publications

Electroweak Parity-Violating Energy Shifts of Amino Acids: The “Conformation Problem”

Electroweak Parity-Violating Energy Shifts of Amino Acids: The “Conformation Problem”

DFT studies using supercells and projector‐augmented waves for structure, energetics, and dynamics of glycine, alanine, and cysteine

Structure of Highly Concentrated Aqueous Lithium Alaninate Solutions Studied by Neutron Diffraction with 14N/15N, 6Li/7Li, and H/D Isotopic Substitution Methods

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