• energies
  • Since there are two possible chair conformation steric and stereoelectronic effects such as the anomeric effect, 1,3 diaxial interactions, dipoles and intramolecular hydrogen bonding must be taken into consideration when looking at relative energies. (wikipedia.org)
  • Note that the two eclipsed conformations have different energies: at 0° the two methyl groups are eclipsed, resulting in higher energy (≈ 5 kcal/mol) than at 120°, where the methyl groups are eclipsed with hydrogens (≈ 3.5 kcal/mol). (wikipedia.org)
  • Atoms above the plane are written before the conformer label, as a superscript Atoms below the plane are written following the conformer label, as a subscript As shown by the relative structure energies in the diagram above, the chair structures are the most stable carbohydrate form. (wikipedia.org)
  • The first is an examination by Csonka and French of the ability of DFT to predict the relative energy of carbohydrate conformation energies. (comporgchem.com)
  • atoms
  • Formally and quantitatively, conformation is captured by description of a molecule's angles-e.g., sets of three sequential atoms (bond angles) and four sequential atoms (torsion angles, dihedral angles), where the locations and angular directions of nonbonding electrons ("lone pair electrons") must sometimes also be taken into account. (wikipedia.org)
  • The envelope conformation has four atoms in a plane while the twist form only has three. (wikipedia.org)
  • While any two arrangements of atoms in a molecule that differ by rotation about single bonds can be referred to as different conformations, conformations that correspond to local minima on the energy surface are specifically called conformational isomers or conformers. (wikipedia.org)
  • In the skew conformation, the plane contains three adjacent atoms and one other with the atom with the lowest possible number exoplanar. (wikipedia.org)
  • This relatively defined and stable conformation means that the hydrogen atoms of the pyranose ring are held at relatively constant angles to one another. (wikipedia.org)
  • Because formaldehyde (n=1) and glycolaldehyde (n=2) are not generally considered to be carbohydrates, the simplest possible aldose is the triose glyceraldehyde, which only contains three carbon atoms. (wikipedia.org)
  • saccharide
  • Conformations adopted by saccharide molecules in response to the physical forces arising from their bonding and nonbonding electrons, modified by the molecule's interactions with its aqueous or other solvent environment, strongly influence their reactivity with and recognition by other molecules (processes which in turn can alter conformation). (wikipedia.org)
  • Among structural properties that could be determined by NMR are primary structure (including stereochemistry), saccharide conformation, stoichiometry of substituents, and ratio of individual saccharides in a mixture. (wikipedia.org)
  • moiety
  • Investigations have shown that changes in the lipid moiety can affect verotoxin binding and that chemical modification can permit recognition of internal Galα1-4Gal under certain conditions, suggesting a degree of flexibility in the carbohydrate conformation. (go.jp)
  • The major and minor components also contain a third carbohydrate moiety - β-D-glucosamine - and differ only by the length and conformation of a side-chain attached to it. (wikipedia.org)
  • amino
  • Mass spectrometric and light scattering experiments both suggested an average mass of approximately 15 kDa for GPEET-PARP, with individual glycoforms ranging from about 12 kDa to 20 kDa, that is consistent with its amino acid and carbohydrate composition. (ox.ac.uk)
  • Carbohydrate-binding module family 1 (CBM1) consists of 36 amino acids. (wikipedia.org)
  • carbons
  • Typical 13C NMR chemical shifts of carbohydrate ring carbons are 60-110 ppm In the case of simple mono- and oligosaccharide molecules, all proton signals are typically separated from one another (usually at 500 MHz or better NMR instruments) and can be assigned using 1D NMR spectrum only. (wikipedia.org)
  • Carbohydrates with more than 4 carbons exist in an equibrium between the closed ring, or cyclic form, and the open-chain form. (wikipedia.org)
  • conformers
  • Pyranose and furanose forms can exist in different conformers and one can interconvert between the different conformations if an energy requirement is met. (wikipedia.org)
  • The three eclipsed conformations with dihedral angles of 0°, 120°, and 240° are not considered to be conformers, but are instead transition states between two conformers. (wikipedia.org)
  • While simple molecules can be described by these types of conformations, more complex molecules require the use of the Klyne-Prelog system to describe the different conformers. (wikipedia.org)
  • 1 They examined 15 conformers of α- and β-D-allopyranose, fifteen conformations of 3,6-anydro-4- O -methyl-D-galactitol and four conformers of β-D-glucopyranose. (comporgchem.com)
  • structure
  • The objectives of this study were to (1) Detect gene silencing-induced changes in carbohydrate molecular structure in an alfalfa forage ( Medicago sativa spp. (gc.ca)
  • The CHO molecular structure changes induced by RNAi gene silencing were associated with biofunctions in terms of the carbohydrate subfractions and nutrient digestion. (gc.ca)
  • A further refinement to the conformation of pyranose rings came when Sponsler and Dore (1926) realized that Sachse's mathematical treatment of six-membered rings could be applied to their X-ray structure of cellulose. (wikipedia.org)
  • All teicoplanins share a same glycopeptide core, termed teicoplanin A3-1 - a fused ring structure to which two carbohydrates (mannose and N-acetylglucosamine) are attached. (wikipedia.org)
  • vicinal
  • Vicinal heteronuclear H-C-O-C coupling constants are used to study torsional angles along glycosidic bond between sugars or along exocyclic fragments, thus revealing a molecular conformation. (wikipedia.org)
  • indicate
  • As the preceding examples indicate that the conformation adopted by the oxalate dianion is dependent upon the size of the alkali metal to which it is bound, some have explored the barrier to rotation about the central C−C bond. (wikipedia.org)
  • interactions
  • Conformations with 1,3 diaxial interactions are usually disfavored due to steric congestion and can shift equilibrium to the other chair form (example: 1C4 to 4C1). (wikipedia.org)
  • Many of these interactions involved carbohydrates found at the cell surface, as part of a membrane glycoprotein or glycolipid. (wikipedia.org)
  • energy
  • If the lone pairs of electrons on the oxygens at the anomeric center of 2-methoxypyran are shown, then a brief examination of the conformations of the anomers reveal that the β-anomer always has at least one pair of eclipsing (coplanar 1,3-interacting) lone pairs, this n-n repulsion is a high energy situation. (wikipedia.org)
  • found
  • He found a molten globule monomeric intermediate during the folding of peanut agglutinin that retained its carbohydrate binding ability - establishing 'wet' molten globule as an "on pathway" folding intermediate and characterized other early intermediates. (wikipedia.org)