The Selenium Speciation Analysis In The Selenium-rich Rice And Selenized Yeast

Selenium is recognized as the necessary nutritional element for human health, which perform many important physiological and biochemical function in the body including anti-oxygenic property,improvement of immunity,prevention of human aging etc. Belonging to trace rare element, selenium is distributed rarely and unevenly on the earth. 2/3 of the area in the world lack selenium, so does in China, of which 1/3 is considered to be extremely lack of selenium. It has been established when the content of selenium is under normal level ,the essential organ such as heart,liver,thyroid grand would be damaged to some extent. Consequently the selenium deficiency will cause many diseases. The Chinese scientists have obtained satisfied results of cureing and preventing the keshan disease and Kashin Beck disease by supplementation of Se. The recently finding show the daily supplement of Se can decrease the occurrence of liver cancer by 50%.Plants is not only the key link through which the inorganic selenium is converted into the organic selenium in the ecological selenium cycle but also the important selenium resource for the human. Selenium in the plants present in many different chemical forms, which determines its bioavailability,efficiency and metabolic pathway. So selenium speciation in plants is much more important in improving effects of selenium supplement and ensuring the human health.On the basis of Osborne fractionation , employing the sequence milled and centrifugal procedure separate and extract protein from the selenium-rich rice including albumin,globulin,prolamin as well as gluletin. Inductively Coupled Plasms Mass (ICPMS) serve as selenium-selected detection method to determine the selenium concentration of protein extraction. Then the using of hyphenated technology of the Size exclusion chromatography coupled to ICPMS (SEC-ICPMS) identifies the molecular mass and character the distribution of selenium contained protein in the albumin extraction. Another hyphenated technology of Reversed-phase ion pairing chromatography combined with ICPMS is used for qualitative and quantitative analysis of selenoaminoacid after extracted through enzymatic digestion and acid hydrolysis from selenium-rich rice and selenized yeast.The result obtained show: the selenium content of protein extraction account for 73% of the total selenium content in selenium-rich rice, so it could be presumed that selenium contained protein is the primary form present in selenium-rich rice. Gluletin is dominating the selenium contained protein which its content is 48% of the total selenium content in selenium-rich rice. It is observed from chromatography of SEC-ICPMS that selenium is identified in the protein with molecular mass 17.9 KDa,12.6KDa,8.35KDa respectively from the albumin extraction, the protein with molecular weight 12.6 KDa is the main selenium contained protein which it take up 50.2% of the total selenium content of the albumin extraction. With respect to the study on selenoaminoacid incorporated into protein, the result is that selenomethionine (SeMet) is the major selenoaminoacid in the selenized yeast which the content is 46% of the overall selenium content of the yeast. In the selenium-rich rice, however, selenomethionine could not be found, the selenocystine (SeCys) and another selenium contained substance with a similar retention time to standard selenomethionine are detected in the chromatography. It needs to further identify and analysis to ensuring the new substance is oxidation of selenomethionine.The results obtained including the selenium concentration of four type of protein extracted from selenium-rich rice,the distribution of selenium contained protein in albumin extraction and the form of selenoaminoacid incorporated into protein can provide the valuable reference about further studying selenium species of associated with protein in selenium-rich rice and assessing the function and nutritional value of rice protein.