Structure and Dynamics of L-Selenomethionine in the Solid State

Abstract

L-selenomethionine 1 crystallizes in P2(1) space group with two molecules in the asymmetric unit. Solid-state NMR spectroscopy is used for searching of structure and dynamics of 1 in the crystal lattice. The distinct molecular motion of side chains for A and B molecules of 1 is apparent from measurements of relaxation parameters (1H 1rho, 13C T1) and analysis of CSA data (2D-PASS experiment). The 13C delta(ii) and 77Se delta(ii) parameters are correlated with theoretical shielding parameters obtained by means DFT GIAO calculations. Attempt to explain the mechanism of phase transition of crystals of 1 at 313K is presented.

Structural Modeling of Djenkolic Acid with Sulfur Replaced by Selenium and Tellurium

“…They are also in accordance with later published sources [8,10,11]. As for the same distances in DjSe, they are identical with those reported on the basis of X-ray studies (1.899–1.97 Å) [9,13]. The X-ray data for DjTe are missing in literature, so we compared our value with data for the C-Te distance characteristic of tellurium-containing organic compounds, which is 2.158 Å [15] exactly the same as found in our present research, and as estimated for telluromethionine earlier [8].…”

“…The main crystallographic data obtained for methionine and selenomethionine so far comprise the crystal structure of d,l -alanylmethionine [10], the crystal structure of the α and β forms of d,l -methionine [11] and the crystal structure of d,l -selenomethionine [9], as well as the crystal and molecular structure of d,l -methionine nitrate [12]. The latest contribution to this topic is a report on the structure and dynamics of l -selenomethionine in the solid state [13] which successfully combines X-ray studies and solid state NMR spectroscopy.…”

Solid-state selenium-77 NMR

“…Methyl-group dynamics was shown to have a significant effect on the selenium chemical shift tensor of L-selenomethionine [114,116]. Gajda et al [114] have calculated the selenium chemical shift tensor in L-selenomethionine using DFT, demonstrating rough agreement with the experimental principal components and that the orientation of d 22 lies perpendicular to the local C d ASeAC c plane, and those of d 11 and d 33 are coincident within this local plane. Selenium analogues of the crown ethers, the polyselenoethers or selenium coronands, show intriguing natural and host-guest conformations.…”

“…Selenomethionine with selenocysteine, amino acids where sulfur has been replaced with selenium, are the primary sources of selenium in the human body [8]. Potrzebowski and coworkers have characterized the selenium chemical shift tensors in the L-and DL-forms of selenomethionine [114][115][116]. Methyl-group dynamics was shown to have a significant effect on the selenium chemical shift tensor of L-selenomethionine [114,116].…”

“…Potrzebowski and coworkers have characterized the selenium chemical shift tensors in the L-and DL-forms of selenomethionine [114][115][116]. Methyl-group dynamics was shown to have a significant effect on the selenium chemical shift tensor of L-selenomethionine [114,116]. Gajda et al [114] have calculated the selenium chemical shift tensor in L-selenomethionine using DFT, demonstrating rough agreement with the experimental principal components and that the orientation of d 22 lies perpendicular to the local C d ASeAC c plane, and those of d 11 and d 33 are coincident within this local plane.…”