Selenomethionine

Selenomethionine

Selenomethionine: chemical structure 100px
Names
IUPAC name 2-Amino-4-methylselanyl-butanoic acid
Other names MSE
Identifiers
CAS Number	3211-76-5 (L) N 1464-42-2 (D/L) N
ChEBI	CHEBI:27585 Y
ChemSpider	14375 Y
Jmol 3D model	Interactive image
PubChem	15103
UNII	964MRK2PEL Y
InChI InChI=1S/C5H11NO2Se/c1-9-3-2-4(6)5(7)8/h4H,2-3,6H2,1H3,(H,7,8) Y Key: RJFAYQIBOAGBLC-UHFFFAOYSA-N Y InChI=1/C5H11NO2Se/c1-9-3-2-4(6)5(7)8/h4H,2-3,6H2,1H3,(H,7,8) Key: RJFAYQIBOAGBLC-UHFFFAOYAT
SMILES C[Se]CCC(C(=O)O)N
Properties
Chemical formula	C5H11NO2Se
Molar mass	196.106 g/mol
Vapor pressure	{{{value}}}
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Selenomethionine is a naturally occurring amino acid. The L-selenomethionine enantiomer is the main form of selenium found in Brazil nuts, cereal grains, soybeans, and grassland legumes, while Se-methylselenocysteine, or its γ-glutamyl derivative, is the major form of selenium found in Astragalus, Allium, and Brassica species. In vivo, selenomethionine is randomly incorporated instead of methionine. Selenomethionine is readily oxidized.

Selenomethionine's antioxidant activity arises from its ability to deplete reactive oxygen species.

Substitution chemistry issues

Selenium and sulfur are chalcogens that share many chemical properties so the substitution of methionine with selenomethionine may have only a limited effect on protein structure and function. However, the incorporation of selenomethionine into tissue proteins and keratin in horses causes alkali disease.

Alkali disease is characterized by emaciation, loss of hair, deformation and shedding of hooves, loss of vitality, and erosion of the joints of long bones.

Incorporation of selenomethionine into proteins in place of methionine aids the structure elucidation of proteins by X-ray crystallography using single- or multi-wavelength anomalous diffraction (SAD or MAD). The incorporation of heavy atoms such as selenium helps solve the phase problem in X-ray crystallography.

Dietary intake

It has been suggested by nutritionists that selenomethionine, which is an organic form of selenium, is easier for the human body to absorb than selenite, which is an inorganic form. It was determined in a clinical trial that selenomethionine is absorbed 19% better than selenite.

See also

• Selenocysteine, another selenium-containing amino acid, but one that is incorporated into specific locations of specific proteins as directed by the genetic code.
• Selenoprotein
• Canadian Reference Material of selenomethionine

External links

• PDB file for MSE
• PDB entries containing Het Group MSE

• P. D. Whanger, Selenocompounds in plants and animals and their biological significance, Journal of the American College of Nutrition, 21(3), 223–232 (2002).
• E. Block, M. Birringer, W. Jiang, T. Nakahodo, H.J. Thompson, P.J. Toscano, H. Uzar, X. Zhang, and Z. Zhu, Allium chemistry: synthesis, natural occurrence, biological activity, and chemistry of Se-alk(en)ylselenocysteines and their γ-glutamyl derivatives and oxidation products, J. Agric. Food Chem., 49, 458-470 (2001).
• W. A. Hendrickson, Maturation of MAD phasing for the determination of macromolecular structures, Journal of Synchrotron Radiation, 6(4), 845-851 (1999).
• A. M. Larsson, Preparation and crystallization of selenomethionine protein, IUL Biotechnology Series, 8 (Protein Crystallization), 135-154 (2009).