富硒农产品中硒代氨基酸形态及其在不同蛋白组分中的分布

Selenium amino acids speciation in selenium-enriched agricultural products and their distribution in different protein components

目的:探究富硒西兰花、富硒大豆、富硒玉米、富硒大麦苗不同溶解性蛋白组分中硒代氨基酸形态及分布情况。方法:利用高效液相色谱—氢化物发生—原子荧光光谱联用技术测定4种富硒禾谷类和十字花科农产品中硒代蛋氨酸(SeMet)、硒代胱氨酸(SeCys2)、甲基硒代半胱氨酸(MeSeCys)和硒代乙硫氨酸(SeEt)含量,并分析各硒代氨基酸在清蛋白、球蛋白、醇溶蛋白和谷蛋白等不同溶解性蛋白组分中的分布特点。结果:4种富硒植物的硒代氨基酸在不同蛋白组分中的含量及分布存在显著差异(P<0.05)。富硒大豆、富硒玉米、富硒大麦苗的有机硒以SeMet形式存在,在4类蛋白组分中分布较一致且相对含量均高于66%,不存在SeEt;富硒西兰花的有机硒主要以SeCys2和SeMet为主、MeSeCys次之,前二者在清蛋白和谷蛋白组分中的分布较一致且约占有机硒含量的36%,但在球蛋白和醇溶蛋白组分中均以SeMet存在,相对含量最高达60%,其次为SeCys2约占有机硒含量的34%。富硒西兰花中存在极少量的SeEt约占有机硒含量的5%。结论:3种禾谷类农产品(富硒大豆、富硒玉米、富硒大麦苗)的不同溶解性蛋白中均以SeMet为主;而富硒西兰花的不同溶解性蛋白则以SeMet和SeCys2为主,并且其清蛋白和谷蛋白还富含较多的MeSeCys。

Objective:This study aimed to explore the distribution and speciation of selenium amino acids in different solubilized proteins of selenium-enriched broccoli,soybean,corn and barley seedlings.Methods:The contents of selenomethionine,selenocysteine,methylselenocysteine and selenethionine in four selenium-enriched cereals and cruciferous agricultural products were determined by high performance liquid chromatography-hydride generation-atomic fluorescence spectrometry.Moreover,the distribution characteristics of each selenium amino acid in albumin,globulin,gliadin and glutelin with different solubilized proteins were analyzed.Results:The content and distribution of selenium amino acids of the four selenium-enriched plants in different protein components were significantly different(P<0.05).SeMet was the main organic selenium form in selenium-enriched soybean,corn and barley seedlings,and its distribution of the four types of protein fractions was more consistent and the relative contents were all higher than 66%.However,no SeEt was detected.The organic selenium forms in selenium-enriched broccoli were mainly SeCys2 and SeMet,following by MeSeCys.SeCys2 and SeMet were more uniformly distributed in the albumin and glutenin which accounted for about 36%of the organic selenium content,but SeMet was present in the globulin and gliadin with the highest relative content of 60%.SeCys2 accounted for about 34%of the organic selenium content,while SeEt was the smallest constituent accounted for about 5%.Conclusion:SeMet is the main selenium specie in different soluble proteins of Graminaceous and cereals(selenium-enriched soybean,corn and barley seedlings);SeMet and SeCys2 are the main selenium species in different soluble proteins of seleniumenriched broccoli,and there are also MeSeCys in albumin and glutelin.