被称为“月亮”的元素——硒

介绍了硒元素的发现历程及其研究现状,重点介绍了含硒高分子的生物医用及自修复材料相关的研究。     

含硒高分子:一类新型生物材料

硒元素是人体必需的微量元素。由于C—Se键和Se—Se键的键能比较低,键比较活泼,使得含硒高分子成为一类特殊的材料,具有许多独特和优异的性质。我们通过多种途径将硒元素引入高分子,设计合成了一系列主链含硒的嵌段高分子、侧链含硒的嵌段高分子以及内核或支化部位含硒的树枝状聚合物,开展了其在氧化、还原以及辐照等多重刺激响应高分子组装体材料方面和高效人工模拟酶方面的研究。研究表明,含硒高分子有可能成为一类新的生物医用高分子材料,具有广阔的应用前景。     

硒的研究进展

综述了微量元素硒的研究进展，包括：基础学研究、临床研究和含硒药物研究进展。     

以蛋自质为基础模拟谷胱甘肽过氧化物酶

硒元素作为一种生命体中必须的微量元素,与人类的健康和疾病息息相关.硒元素主要以硒代半胱氨酸的形式存在于至少25种硒蛋白中,执行着多种生物功能.在这20多种硒蛋白中,谷胱甘肽过氧化物酶( GPx)作为一种主要的抗氧化酶,能够有效地利用谷胱甘肽还原氢过氧化物以防止机体的氧化损伤.这里,我们主要介绍以蛋白质为骨架构筑GPx模...     

硒氰酸酯合成方法及硒氰酸酯化合物生物活性研究进展

硒元素作为生物体的必需微量元素,在人类的生长及发育过程中发挥着极其重要的生理作用。有机硒化合物在抗氧化、抗炎、抗肿瘤等方面展现出卓越的生物活性,对有机硒化合物的开发应用研究是目前化学、生命科学、临床医学等研究领域的一个研究热点。硒氰酸盐是有机硒中的一类含硒化合物,近年来,很多学者开发了不少在有机化合物中直接引入硒氰基官能团的新方法,并合成了许多新型有机硒氰基化合物,这些化合物显示出不同的生物活性,引起人们对硒氰基官能团的极大兴趣。本文主要综述了硒氰酸酯化合物的合成方法研究及非甾体硒氰基化合物和甾体硒氰基化合物的研究进展,并初步探讨有机硒的发展及应用前景,希望为具有不同生物活性的新型有机硒分子的设计合成提供有用参考。     

四川兴文地区硒的地球化学特征及生物效应

四川兴文土地质量调查显示:兴文县表层土壤中硒质量分数为0.075~2.540 mg/kg,平均值为0.43 mg/kg,富硒土地面积占调查面积53.25%,合计734.75 km^2。全区大米硒质量分数平均值为0.064 mg/kg,硒含量处于较为富足水平。水稻中的硒元素含量与根系土中硒元素呈明显正相关关系。根系土中水溶态硒和离子交换态硒含量高时,土壤容易产出富硒作物。     

以蛋白质为基础模拟谷胱甘肽过氧化物酶

硒元素作为一种生命体中必须的微量元素,与人类的健康和疾病息息相关.硒元素主要以硒代半胱氨酸的形式存在于至少25种硒蛋白中,执行着多种生物功能.在这20多种硒蛋白中,谷胱甘肽过氧化物酶(GPx)作为一种主要的抗氧化酶,能够有效地利用谷胱甘肽还原氢过氧化物以防止机体的氧化损伤.这里,我们主要介绍以蛋白质为骨架构筑GPx模拟物的一些策略和方法,以期望于能够更好的理解硒蛋白的生物学性质,甚至开拓更为有效的技术去模拟这种抗氧化酶.     

碘量法测定复杂含硒物料中常量硒

用碘量法测定复杂含硒物料中常量硒并对测定条件做试验。试样经硝酸及硫酸溶解、蒸发至冒烟后,盐类溶于盐酸中。在酒石酸存在下加盐酸羟胺,于70℃保温1h,放置1.5h使硒还原为单质硒并陈化。过滤,将单质硒溶于盐酸中,溶解温度为90℃,溶解时间为5min,滴定时溶液酸度宜在0.2~0.5mol·L-1(盐酸介质)。滴定时采用分步滴加碘化钾溶液,随即用硫代硫酸钠标准溶液滴定至淀粉指示剂所显蓝色消失,至再次加入碘化钾无蓝色出现为终点。按所耗硫代硫酸钠标准溶液的体积计算试样的含硒量。     

含活性基荧光素衍生物

介绍了近20年来含活性基荧光素衍生物的最新研究成果,重点介绍了含活性基的荧光素探针在生物分析中的应用及改进。     

一种新的人血浆中含硒蛋白测定方法

提出一个综合聚丙酰胺凝胶电泳分离和２,３－二氨基萘柱前衍生正相液体色谱测定硒的方法（ＤＡＮ－ＨＰＬＣ－ＦＬＤ）,分离测定了高硒地区人血浆中的含硒蛋白。在所鉴定的５种含硒蛋白中,其中至少有３种是从未明确鉴定过的含硒蛋白。     

富硒灵芝中一种新含硒蛋白的纯化、性质及其自由基清除活性研究

通过硫酸铵沉淀、离子交换层析和分子排阻层析等方法, 从富硒灵芝中获得了一种新的含硒蛋白, 命名为Se-GL-P, 并研究了此蛋白的性质、抗氧化活性与其硒含量间的关系. 结果表明, 此蛋白的分子量为36600, 分子中约含有19.8%的糖链, N端的氨基酸残基序列为DINGGGATLPQKLYLTPDVL, 属于DING蛋白家族. 硒含量为4.87 mg/g, 具有较高的羟自由基和超氧自由基清除活性. 研究发现, Se-GL-P的抗氧化活性的提高与其中硒含量的提高相关.     

A metallomics approach discovers selenium-containing proteins in selenium-enriched soybean

Our previous study found that high-molecular-weight selenium (Se) species make up 82% of the total Se in the bean of Se-enriched soybean plants (Chan et al. 2010, Metallomics, 2(2): p. 147–153). The Se species have been commonly seen in other plants in addition to soybean, but their identities remain unresolved. The present study employs a multi-technique metallomics approach to characterize the proteins containing Se in the beans of Se-enriched soybean plants. Two main categories of proteins, maturation proteins and protease inhibitors, were found in Se-containing high-performance liquid chromatography (HPLC) fractions. The proteins were screened by two-dimensional HPLC-inductively coupled plasma mass spectrometry, size-exclusion chromatography, and anion-exchange chromatography, and the Se-containing fractions were then identified by peptide mapping using HPLC-Chip-electrospray ion trap mass spectrometry. Based on the belief that Se goes into proteins through non-specific incorporation, a new method was designed and applied for the Se-containing peptide identification. The Se-containing peptide KSDQSSSYDDDEYSKPCCDLCMCTRS, part of the sequence of protein Bowman–Birk proteinase isoinhibitor (Glycine max), was found in one of the Se-containing fractions. The nutritional value of the Se-containing proteins in Se-enriched soybeans will be an interesting topic for the future studies.     

含硒磺基甜菜碱表面活性剂界面性能的氧化-还原响应行为

硒,作为一种新的氧化-还原响应位点因其良好的生物相容性日益引起人们的关注,然而,对这种新型氧化-还原响应型表面活性剂的研究相对较少,尤其是其界面性能的智能调控。本文以含硒两性离子表面活性剂苄基十一烷基磺基甜菜碱(BSeUSB)为对象,研究了其分子结构、Krafft温度、表/界面张力及发泡和乳化性能的氧化-还原刺激响应行为。发现在极微量的H_2O_2(≤体系总质量的0.056%)氧化下,BSeUSB分子中疏水的―Se―C―键转变成了具有一定亲水能力的Se=O键,表面活性剂从单头单尾的还原态变成了类Bola型的氧化态,导致表面活性剂的Krafft温度由(23.5±0.5)°C下降至0°C以下,5.00 mmol?L~(-1)时的表/界面张力分别从45.15、5.52 mN·m~(-1)升高至61.63、18.38 m N·m~(-1)。宏观上,还原态具有良好的发泡和乳化性能,而氧化态的发泡和乳化能力几乎消失。再次加入极少量还原剂Na_2SO_3(≤体系总质量的0.060%)后,分子的微观结构和溶液性能又可恢复到初始状态。总之,通过极微量H_2O_2和Na_2SO_3的交替加入,我们实现了该表面活性剂界面性能的智能调控。     

Purification and characterization of two major selenium-containing proteins in selenium-rich silkworm pupas

Selenium (Se) is an essential trace element in vivo involved in the defense against oxidative stress. Se deficiency is associated with many human diseases. The bioactivity of Se is dose- and species-dependent. Silkworm pupa has been reported to accumulate Se mainly in proteins. Thus the characterization of major Se-containing proteins is very important in the application of Se-rich silkworm pupas in food and drugs. In this study, crude proteins were extracted from Se-rich silkworm pupas, followed by DEAE-Sepharose and Sephedex G-75 chromatography. Se content was measured after each step to determine the highest Se-containing fraction for the next step of separation. The proteins obtained were analyzed using SDS-PAGE, followed by in-gel digestion with trypsin, and were characterized by MALDI-TOF MS and ESI-MS/MS. These data showed two proteins mainly accumulated Se in the silkworm pupas. Those two proteins were proven by mass spectrometry to be arylphorin and sex-specific storage-protein 2 precursor (SP-2), respectively. Both of them belong to the storage proteins of amino acids during metamorphosis and the non-feeding pupal stage. The results suggest that Se could be enriched by storage proteins and be supplied to silkworm pupas in accompany with amino acids for the synthesis of new Se-containing proteins and peptides.     

Current mass spectrometry strategies for selenium speciation in dietary sources of high-selenium

This document reviews the most relevant mass spectrometry approaches to selenium (Se) speciation in high-Se food supplements in terms of qualitative and quantitative Se speciation and Se-containing species identification, with special reference to high-Se yeast, garlic, onions and Brazil nuts. Important topics such as complexity of Se speciation in these materials and the importance of combining Se-specific detection and molecule-specific determination of the particular species of this element in parallel with chromatography, to understand their nutritional role and cancer preventive properties are critically discussed throughout. The versatility and potential of mass spectrometric detection in this field are clearly demonstrated. Although great advances have been achieved, further developments are required, especially if speciatedcertified reference materials (CRMs) are to be produced for validation of measurements of target Se-containing species in Se-food supplements.     

Identification of the Primary Structure of Selenium-Containing Polysaccharides Selectively Inhibiting T-Cell Proliferation

We previously described the biosynthesis, isolation, and immunosuppressive activity of the selenium-containing polysaccharide fraction isolated from the mycelial culture of Lentinula edodes. Structural studies have shown that the fraction was a protein-containing mixture of high molar mass polysaccharides α- and β-glucans. However, which of the components of the complex fraction is responsible for the immunosuppressive activity non-typical for polysaccharides of fungal origin has not been explained. In the current study, we defined four-polysaccharide components of the Se-containing polysaccharide fraction determined their primary structure and examined the effect on T- and B-cell proliferation. The isolated Se-polysaccharides, α-1,4-glucan (M_w 2.25 × 10⁶ g/mol), unbranched β-1,6-d-glucan, unbranched β-1,3-d-glucan and β-1,3-branched β-1,6-d-glucan (M_w 1.10 × 10⁵ g/mol), are not typical as components of the cell wall of L. edodes. All are biologically active, but the inhibitory effect of the isolated polysaccharides on lymphocyte proliferation was weaker, though more selective than that of the crude fraction.     

高效液相色谱-等离子体质谱联用方法研究富硒大米中硒的形态

根据Osborne溶解性蛋白质分类法,用去离子水、2%NaCl溶液、70%乙醇、0.5%KOH4种溶液分别提取出大米中相应的清蛋白、球蛋白、醇溶蛋白及谷蛋白。利用电感耦合等离子质谱(ICP-MS)测量各类蛋白提取液中的硒含量;用色谱与质谱联用法对大米蛋白提取液中含硒蛋白组分及含硒氨基酸组成进行初步分析。结果表明:大米中的硒主要与蛋白质结合,在4类蛋白提取液中硒含量由高到低的分布顺序为:谷蛋白、醇溶蛋白、清蛋白和球蛋白。清蛋白提取液中,分子量为12.6 kDa蛋白是主要的含硒蛋白组分;大米中约30%的硒以硒代半胱氨酸形式存在。     

用于一氧化氮检测的小分子荧光探针研究进展

生物小分子NO以其重要的生理学和病理学作用受到科学家们的广泛关注。高选择性、高灵敏度、低毒性NO分子荧光探针的设计和开发,在环境检测、食品安全及人体内NO检测等领域具有重要意义。本文以小分子荧光探针对NO的识别机制为主线,从唑环的形成、螺内酰胺开环、还原脱氨、二氢吡啶的芳构化、NO与金属络合物的反应、与非金属Se的反应和亚硝胺的形成出发,综述了近年来NO小分子荧光探针的研究进展。对NO探针设计及其识别性能研究方面的工作进行了总结,并讨论了NO荧光探针今后的设计思路和重点研究方向。     

Synthesis of novel di-Se-containing thymidine and Se-DNAs for structure and function studies

The selenium derivatization of nucleic acids and nucleic acid-protein complexes has provided a powerful tool to solve phase problem in X-ray crystallography.Selenium atoms in the nucleotides can serve as fine scattering centers in crystal diffraction.Towards the synthesis of multiple selenium atom-containing nucleotides,which offers strong phasing power to facilitate crystal structure determination,we report here the synthesis of the thymidine analogue containing two Se atoms in one nucleobase.The novel Se-containing nucleoside and oligonucleotide DNAs were synthesized and found with the red-shifted UV spectrum and yellow color.Their unique properties are useful in phase determination,nucleic acid-based detection as well as spectroscopic studies of nucleic acids and nucleic acid-protein complexes.     

Epithermal neutron activation analysis of blue-green algae Spirulina platensis as a matrix for selenium-containing pharmaceuticals

To evaluate the potentiality of the blue-green algae Spirulina platensis as a matrix for the production of Se-containing pharmaceuticals, the background levels of 31 major, minor and trace elements (Na, Mg, Al, Cl, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni using (n,p) reaction), As, Br, Zn, Rb, Mo, Ag, Sb, I, Ba, Sm, Tb, Tm, Hf, Ta, W, Au, Hg, Th were determined in Spirulina platensis biomass by means of epithermal neutron activation analysis. The possibility of the purpose-oriented incorporation of Se into Spirulina platensis biomass was demonstrated. The polynomial dependence of the Se accumulation on nutritional medium loading was revealed. The analytical technique used allows to control the amount of toxic elements in algae Spirulina platensis. Based on this study, a conclusion of the possibility to use Spirulina platensisas a matrix for the production of Se-containing pharmaceutical was drawn.