Separation 、 Preparation Method And Structural Characterization Of Selenoprotein In Selenium-enriched Corn

As a key trace element,selenium(Se)plays an important role in the growth and development of antioxidants in humans and animals.The human body and the animal mainly rely on food to supplement selenium,but the excessive concentration of selenium can cause poisoning symptoms.The organic selenium is less toxic than inorganic selenium and the absorption rate in the body is much higher than that of inorganic selenium.As a non-selenium-concentrating plant,the use of corn in the human body can avoid the symptoms of poisoning caused by excessive intake of selenium.Therefore,this study used selenium-enriched corn in Ankang as raw material to analyze the distribution of selenium in corn,amino acid composition,selenium form of selenium-enriched corn and secondary structure and antioxidant activity of different selenoproteins.Selenium-enriched corn-containing selenoproteins were optimized,extracted,purified,and characterized,in order to lay the foundation for the development of selenium-enriched corn and related functional additives in Ankang.The main findings are as follows:(1)Ankang selenium-enriched corn protein content is 8.94%,total selenium content is0.097 mg/kg,and selenoprotein accounts for 75.20% of organic selenium.The protein in corn is mainly in the form of alkali-soluble protein and alcohol-soluble protein,but selenium is combined.The ability is salt-soluble selenoprotein> alkali-soluble selenoprotein>water-soluble selenoprotein> alcohol-soluble selenoprotein,the main amino acid of selenoprotein in corn is selenocystine,and the form of inorganic selenium is selenite.(2)The selenoside protein extracted from the four fractions was analyzed by Fourier transform infrared spectroscopy.The water-soluble selenoprotein,salt-soluble selenoprotein,alcohol-soluble selenoprotein and alkali-soluble selenoprotein were various complex proteins,except for alkali solubility.In addition to the protein,the other three proteins have distinct characteristics in the characteristic absorption band.Furthermore,the percentage of secondary structure of four selenoproteins from 1600cm-1 to 1700cm-1 was analyzed by curve fitting method.The results of infrared spectroscopy showed that the contents of sele-containing proteins were all other than alkali-soluble proteins.Different,the structure is relatively stable.The salt-soluble selenoprotein in corn has a relatively high antioxidant activity.In general,the oxidative capacity of selenoprotein in corn(except for denatured alkali-soluble selenoprotein)has a good consistency with the ability of selenium-binding protein.(3)Ultrasound-assisted phosphate extraction method was used to optimize the extraction of selenoprotein from selenium-enriched corn by BBD response surface analysis based on single factor test.Optimization results: temperature 37℃,time 80 min,buffer p H selected as7.7,corn selenoprotein yield can reach 41.5345%,through the antioxidant test can be obtained by this method of selenoprotein extraction compared to the above four The selenoprotein has a higher antioxidant activity.Therefore,selenium-enriched protein extracted by selenium-enriched method was selected as a further research object.(4)The selenoprotein of maize was purified by Q Sepharose Fast Flow strong anion exchange column.After SDS-PAGE,two bands were named,Z1 and Z2,respectively.After LC-MS/MS test,two selenoproteins were used.Identification,Z1 identified three proteins,one is glutathione transferase,one is ribonuclease,and the other may be glutathione peroxidase;Z2 Two proteins were identified,one of which was unmatched selenoprotein and the other was purple acid phosphatase.