Selenomethyl selenocysteine (BioDeep_00000616984)

描述信息

Selenomethionine is an amino acid containing selenium that cannot be synthesized by higher animals, but can be obtained from plant material. Selenomethionine is the major seleno-compound in cereal grains (wheat grain, maize and rice), soybeans and enriched yeast. Seleno-compounds present in plants may have a profound effect upon the health of animals and human subjects. It is now known that the total Se content cannot be used as an indication of its efficacy, but knowledge of individual selenocompounds is necessary to fully assess the significance. Thus, speciation of the seleno-compounds has moved to the forefront. Since animals and man are dependent upon plants for their nutritional requirements, this makes the types of seleno-compounds in plants even more critical. Se enters the food chain through incorporation into plant proteins, mostly as selenocysteine and selenomethionine at normal Se levels. There are two possible pathways for the catabolism of selenomethionine. One is the transsulfuration pathway via selenocystathionine to produce selenocysteine, which in turn is degraded to H2Se by the enzyme b-lyase. The other pathway is the transamination-decarboxylation pathway. It was estimated that 90\\% of methionine is metabolized through this pathway and thus could be also the major route for selenomethionine catabolism. (PMID: 14748935, Br J Nutr. 2004 Jan;91(1):11-28.); Selenomethionine is an amino acid containing selenium. The L-isomer of selenomethionine, known as Se-met and Sem, is a common natural food source of selenium. In vivo, selenomethionine is randomly incorporated instead of methionine and is readily oxidized. Its antioxidant activity arises from its ability to deplete reactive species. Selenium and sulfur are chalcogen elements that share many chemical properties and the substitution of methionine to selenomethionine may have no 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. Selenomethyl selenocysteine is found in garden onion.

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