%0 Journal Article %1 Stenutz:1997:Glycoconj-J:9486430 %A Stenutz, R %A Widmalm, G %D 1997 %J Glycoconj J %K carbohydrate conformation dynamics hydroxymethyl j-coupling langevin modeling molecular nmr %N 8 %P 973-981 %T Conformational analysis of methyl 6-O-(R)- and (S)-1-carboxyethyl-alpha-D-galactopyranoside by MM and Langevin dynamics simulations %U http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&dopt=Abstract&list_uids=9486430 %V 14 %X The conformational space of methyl 6-O-(R)- and (S)-1-carboxyethyl-alpha-D-galactopyranoside has been investigated. A grid search employing energy minimization at each grid point over the three major degrees of freedom, namely phi, psi and omega, identified low energy regions. The R-isomer shows five low energy conformers within ca. 1 kcal mol(-1) of the global energy minimum. The S-isomer has two conformers within a few tenths of a kcal mol(-1) of the global energy minimum. Langevin dynamics simulations have been have been performed at 300 K for 30 ns of each isomer. The phi dihedral angle has as its major conformer (g-) for the R-isomer whereas it is the (g+) conformer for the S-isomer. For the psi dihedral angle the (t) conformer has the highest population for both isomers. The dihedral angle omega has the (g+) conformer most highly populated, both for the R- and S-isomer. The above five and two conformational states for the R- and S-isomers, respectively, make up 90% in each case of the populated states during the Langevin dynamics (LD) simulations. Rate constants for the omega dihedral angle have been calculated based on a number correlation function. Three bond homo- and heteronuclear, i.e. proton and carbon-13, coupling constants have been calculated from the dynamics trajectories for comparison to experimental values. The heteronuclear coupling constant H2',C6 has been measured for the S-isomer and found to be 3.3 Hz. The J value calculated from the LD simulations, namely 2.6 Hz, is in fair agreement with experiment. A comparison to the X-ray structure of the R-isomer shows that the conformation of the crystalline compound occupies the low energy region most highly populated as a single R-conformer (30%) during the LD simulations.

@article{Stenutz:1997:Glycoconj-J:9486430, abstract = {The conformational space of methyl 6-O-[(R)- and (S)-1-carboxyethyl]-alpha-D-galactopyranoside has been investigated. A grid search employing energy minimization at each grid point over the three major degrees of freedom, namely phi, psi and omega, identified low energy regions. The R-isomer shows five low energy conformers within ca. 1 kcal mol(-1) of the global energy minimum. The S-isomer has two conformers within a few tenths of a kcal mol(-1) of the global energy minimum. Langevin dynamics simulations have been have been performed at 300 K for 30 ns of each isomer. The phi dihedral angle has as its major conformer (g-) for the R-isomer whereas it is the (g+) conformer for the S-isomer. For the psi dihedral angle the (t) conformer has the highest population for both isomers. The dihedral angle omega has the (g+) conformer most highly populated, both for the R- and S-isomer. The above five and two conformational states for the R- and S-isomers, respectively, make up 90% in each case of the populated states during the Langevin dynamics (LD) simulations. Rate constants for the omega dihedral angle have been calculated based on a number correlation function. Three bond homo- and heteronuclear, i.e. proton and carbon-13, coupling constants have been calculated from the dynamics trajectories for comparison to experimental values. The heteronuclear coupling constant H2',C6 has been measured for the S-isomer and found to be 3.3 Hz. The J value calculated from the LD simulations, namely 2.6 Hz, is in fair agreement with experiment. A comparison to the X-ray structure of the R-isomer shows that the conformation of the crystalline compound occupies the low energy region most highly populated as a single R-conformer (30%) during the LD simulations.}, added-at = {2007-07-18T20:51:39.000+0200}, author = {Stenutz, R and Widmalm, G}, biburl = {https://www.bibsonomy.org/bibtex/2c90813eb05016d1011ca40d1cdb9c1f9/rstenutz}, description = {Conformational analysis of methyl 6-O-[(R)- and (S...[Glycoconj J. 1997] - PubMed Result}, interhash = {0768f9e38ff924e9c445ab7edaecc7e9}, intrahash = {c90813eb05016d1011ca40d1cdb9c1f9}, journal = {Glycoconj J}, keywords = {carbohydrate conformation dynamics hydroxymethyl j-coupling langevin modeling molecular nmr}, month = Dec, number = 8, pages = {973-981}, pmid = {9486430}, timestamp = {2007-07-18T20:51:39.000+0200}, title = {Conformational analysis of methyl 6-O-[(R)- and (S)-1-carboxyethyl]-alpha-D-galactopyranoside by MM and Langevin dynamics simulations}, url = {http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&dopt=Abstract&list_uids=9486430}, volume = 14, year = 1997 }