摘要
【目的】探索不同萌发时期绿豆分离蛋白、清蛋白、球蛋白、谷蛋白和醇溶蛋白含量的动态变化规律,以及蛋白质组分(分离蛋白、球蛋白和清蛋白)的亚基组成及含量变化,为绿豆蛋白的加工利用提供科学依据。【方法】采用等电点沉淀法提取绿豆分离蛋白,并根据Osborne分类法制备绿豆清蛋白、谷蛋白、球蛋白和醇溶蛋白,比较分析萌发前后绿豆分离蛋白及各蛋白组分含量的变化,同时通过SDS-PAGE电泳进一步分析萌发前后蛋白亚基组成及数量的变化。【结果】随着萌发时间的延长,绿豆分离蛋白的含量呈现先增高后下降的趋势,萌发36 h时与未萌发的绿豆相比提高了9.4%。绿豆清蛋白含量随着萌发时间的延长呈逐渐下降的趋势,萌发84 h时含量最小,为20.47 mg·g^(-1)。球蛋白随着萌发时间的延长呈现先升高后下降的趋势,萌发48 h时其含量最大,且比未萌发时提高了3.47倍。萌发对绿豆醇溶蛋白的含量变化影响不大。绿豆谷蛋白含量在萌发12—36 h和48—72 h变化无明显差异,但相对于未萌发的绿豆仍有一定程度的提高。绿豆蛋白酶活性在萌发36 h后不断上升,变化相对较大,72 h时开始下降。SDS-PAGE电泳图及光密度扫描分析结果发现,绿豆分离蛋白主要由7条条带组成(Ⅰ—Ⅶ),萌发过程中各条带相对含量不断减少,随着萌发时间的延长,分子量在25—66 k D的条带含量逐渐降低,分子量在18—25 k D的亚基条带含量在萌发的前72 h有所增加,萌发至96 h时几乎只剩下Ⅳ条带。绿豆清蛋白主要由4条条带组成(Ⅰ—Ⅳ),分子量分别为61.56、48.99、29.88和20.42 k D,萌发过程中条带Ⅰ相对含量从0 h的18.4%降至60 h的16.4%,萌发72 h后条带Ⅰ消失;条带Ⅱ在萌发过程中始终存在,但是含量不断减少;条带Ⅲ和条带Ⅳ也在萌发过程中不断减少,萌发72 h后消失。同时,分子量为18—25 k D的亚基条带相对含量在24—60 h增加,萌发至72 h逐渐消失,几乎只剩下条带Ⅱ。绿豆球蛋白主要由5条条带组成(Ⅰ—Ⅴ),分子量分别为66、61、50、32和26 k D。萌发过程中亚基条带Ⅰ和Ⅱ都在萌发96 h时消失;而条带Ⅲ在萌发过程前期(0—60 h)相对含量逐渐增大,为34.4%—41.8%,萌发72 h后条带Ⅲ含量迅速下降,萌发至96 h时仅为10.8%;亚基条带Ⅳ和Ⅴ萌发至84 h后消失。分子量在18—25 k D的亚基条带在萌发24—60 h时有所增加,随着萌发时间的延长,出现降解甚至消失。【结论】适当萌发能提高蛋白的含量,促进大分子亚基发生水解,同时有利于小分子亚基或多肽生成,但萌发时间过长并不完全利于蛋白的利用。
【Objective】In order to provide the scientific basis for processing and utilization of mung bean protein,the dynamic changes of mung bean isolated protein,albumin,globulin,gluten and gliadin in different germination stages were investigated.【Method】The isolated protein of mung bean were extracted by isoelectric point precipitation method,and the albumin,gluten,globulin and gliadin of mung bean were prepared according to Osborne classification.The content of each kind of proteins and the activity of protease were determined in different germination period.The changes of composition and quantity of protein subunit before and after germination were further analyzed by SDS-PAGE electrophoresis.【Result】With the extension of germination time,the contents of mung bean isolated protein increased first and then decreased.The mung bean isolated protein was increased by 9.4%compared to non-germinated mung bean.The mung bean albumin content was decreased after the germination,which the minimum value was 20.47 mg·g^-1.The globulin content was increased first and then decreased with the increasing of germination time,with the minimum was observed at 0 h and the highest at 48 h after germination.However,the gliadin content was not influenced by the germination.There was no significant difference in the gluten content of mung bean between the 12-36 h and 48-72 h germination,but the content is still higher than non-germinated seed.Mung bean protease activity increased within 36 h germination,and began to decline at 72 h.Analysis of SDS-PAGE electrophoresis and optical density scanning results showed that there were 7 bands(Ⅰ-Ⅶ)in the mung bean isolated protein,and the relative content of each band decreased continuously.After the germination,the molecular weight of 25 kD to 66 kD proteins gradually decreased.The content of 18 kD and 25 kD isolated proteins increased within 72 h germination,and almost only remainedⅣafter 96 h of germination.Mung bean albumin mainly consisted of four bands(Ⅰ-Ⅳ)with molecular weights of 61.56,48.99,29.88 and 20.42 kD,respectively.During the germination process,the relative content of Band I decreased from 18.4%at 0 h to 16.4%at 60 h,and disappeared at 72 h after germination.Although the Band II existed during the whole germination,the relative content of Band II was decreased continuously from 51.1%to 27.0%.BandsⅢandⅣdecreased continuously with the germination,and disappeared after 72 h of germination.What’s more,the relative contents of subunit bands with a molecular weight of 18-25 kD increased at 24-60 h and disappeared after 72 h of germination.Mung bean globulin mainly consists of five bands(Ⅰ-Ⅴ)with molecular weights of 66,61,50,32 and 26 kD,respectively.The relative content of subunit bands I and II were disappeared after 96 h of germination.While the relative content of bandⅢincreased gradually from 34.4%to41.8%during 0 to 60 h of early stage of germination.Then the bandⅢcontent decreased rapidly after 72 h of germination and measured only 10.8%at 96 h.In the meantime,the relative contents of subunit BandⅣandⅤwas not observed after 84 h germination.Subunit bands with a molecular weight of 18-25 kD increased during 24 to 60 h of germination,and then degraded or even disappeared with the germination process.【Conclusion】Appropriate germination not only increase the content of mung bean proteins and promote the hydrolysis of macromolecular subunits,but also facilitates the formation of small molecule subunits or polypeptides.
作者
赵天瑶
张亚宏
金涛
康玉凡
ZHAO TianYao;ZHANG YaHong;JIN Tao;KANG YuFan(College of Agronomy, China Agricultural University, Beijing 100193;Engineering Research Center of Ecology and Agricultural Use of Wetland, Ministry of Education/Hubei Key Laboratory of Waterlogging Disaster and Wetland Agriculture Jingzhou 434025, Hubei)
出处
《中国农业科学》
CAS
CSCD
北大核心
2018年第9期1783-1794,共12页
Scientia Agricultura Sinica
基金
国家现代农业(食用豆)产业技术体系建设专项(CARS-08-07B)
关键词
绿豆
萌发
蛋白组分
亚基
mung bean
germination
protein component
subunit