Description | 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.) |