二甲基氨基甲叉二膦酸氮氧化物的合成

以二甲基氨基甲叉二膦酸(DMMP)为原料,双氧水为氧化剂合成二甲基氨基甲叉二膦酸氮氧化物(DMMPO)。研究了原料配比、温度、时间及合成时pH值等条件对目标产物阻磷酸钙垢效果的影响,结果表明:n(DMMP)∶n(H2O2)=1∶3、反应温度为75℃、反应时间为2.5 h,并控制pH值为9左右时合成的DMMPO静态阻垢效果最好。通过IR和31P-NMR对产物进行了结构鉴定,同时对产品进行了活性物含量、亚磷酸根和磷酸根含量的测定,直接合成产物中活性组分含量为22.7%,亚磷酸根和磷酸根含量均小于0.1%。     

Macromolecular recognition by cyclodextrins. Interaction of cyclodextrins with polymethacrylamides bearing hydrophobic amino acid residues

The interaction of cyclodextrins (CDs) with poly(N-methacryloyltryptophan) (pMTrp) and with poly(N-methacryloylphenylalanine) (pMPhe) was investigated as a simple model system of macromolecular recognition of proteins. The association constants (K) for the model compounds, sodium salts of tryptophan and phenylalanine, are not so different (i.e. 43 and 16 M⁻¹ for α-CD, 59 and 69 M⁻¹ for β-CD, and 12 and 3 M⁻¹ for γ-CD, respectively). On the other hand, there is a significant difference in the apparent K values for pMTrp and pMPhe (i.e. the K values for pMPhe are considerably smaller than ca. 10 M⁻¹, whereas those for pMTrp are 30, 83, and 11 M⁻¹ for α-, β-, and γ-CDs, respectively). These observations indicate that a subtle difference in polymer side chains can be critical in macromolecular recognition.     

Composition analysis of {alpha}-helices in thermophilic organisms

We present a statistical comparison of the amino acid compositionin a secondary structure element, the -helix, of proteins stableat high temperatures with those which are less so. This studyhas shown that the temperature-dependent Zimm-Bragg helix propagationvalue s is not a good predictor for the helix-forming tendencyof an amino acid in thermostable proteins. However, we haveshown that s, the change in s from 20 to 60°C, accuratelypredicts the direction of the probability shift for 15 aminoacids in thermostable protein a-helices, although it does notpredict the magnitude of that change. The residues tyrosine,glycine and glutamine show a significant increase in residencyin a-helices for thermostable proteins over their nonthermostablecounterparts. Significant decreases in -helix residency occurfor the residues valine, glutamic acid, histidine, cysteineand aspartic acid in proteins from thermophilic organisms. Aromaticinteractions, hydrogen bonding and a reduction of charge mayexplain the increase observed for tyrosine and glutamine andthe decrease in glutamic acid and aspartic acid, although packingconsiderations cannot be ruled out The only physical explanationfor the increase in glycine would seem to be its positive svalue     

甜菜雄性不育系及保持系花期蛋白差异分析

为揭示甜菜雄性不育的原因,从蛋白质组学角度对甜菜细胞质雄性不育进行研究,利用双向电泳与MALDI-TOF-MS方法,对Owen型甜菜质核互作型雄性不育系DY5-CMS及同型保持系DY5-O花粉发育3个阶段(雄蕊原基分化期、四分体时期和单核时期)的花蕾蛋白差异表达进行研究．结果表明： 在雄蕊原基分化期花蕾中鉴定出6个差异蛋白,在四分体时期鉴定出4个差异蛋白,这些蛋白多数与呼吸和能量代谢有关,推测甜菜细胞质雄性不育可能是花粉发育早期(雄蕊原基分化期和四分体时期)与能量和呼吸代谢有关的蛋白表达上调导致呼吸和能量代谢紊乱造成的;在花粉发育的单核时期鉴定出6个差异蛋白,这些蛋白主要与植物的光合作用有关,推测到花粉发育后期雄性不育性状已形成,雄性不育导致植物光合机能下降．     

胺基咪唑功能离子液体［ NH2 e-mim ］［ BF4］的合成与制备

胺基咪唑功能离子液体在固定CO2方面具有独特的优势,但其合成制备步骤复杂,产率低,成本高等局限了它的广泛应用。采用两步合成法合成了1-（1-胺乙基）-3-甲基咪唑氟硼酸盐（[ NH2 e-mim][ BF4]）,通过核磁共振和红外光谱进行结构表征,并测定了其纯度及密度、黏度、表面张力、电导率等物理化学性质。实验表明：离子液体（简称IL）合成最佳工艺条件是原料配比n（3-溴丙胺氢溴酸盐）/n（ N-甲基咪唑）＝1．1,以乙醇为溶剂,在343 K下反应24 h,减压蒸馏提纯;合成物胺的含量均在0．9355 mol NH2/mol IL以上,纯度较高;红外光谱法和核磁共振氢谱分析表明合成了目标产物,298 K下合成的产物的物化性质与文献报道的相近。     

水利现代化对广西蔗糖业发展的影响分析

广西是糖料蔗主产区,目前正大力推进高产高糖糖料蔗基地建设,水利现代化建设是其中的重要内容。系统分析水利现代化对蔗糖产业的影响,并就加快蔗区水利现代化建设提出了建议。     

Isoform-specific expression and characterization of 14-3-3 proteins in human glioma tissues discovered by stable isotope labeling with amino acids in cell culture-based proteomic analysis

Human 14-3-3 proteins have isoform-specific expression and functions in different kinds of normal or tumor cells and tissues. However, the expression profiling of 14-3-3 proteins and isoform-specific biological functions are unclear in human glioma so far. In our study, the expression levels and characterization of 14-3-3 isoforms in human glioma tissues were investigated by a sensitive, accurate stable isotope labeling with amino acids in cell culture-based quantitative proteomic strategy. As a result, except unexpressed 14-3-3σ, the other six isoforms, with different expression levels, were existed in glioma tissues and para-cancerous brain tissues (PBTs). 14-3-3β and η were upregulated, whereas 14-3-3ζ was downregulated in glioma tissues compared with that in PBTs. And the other three isoforms 14-3-3ε, θ, and γ had similar expression levels in human glioma tissues and PBTs. Western blot and immunohistochemistry analysis were both consistent with the quantitative proteomic data. The loss of expression of 14-3-3σ was further discovered due to DNA high methylation in its coding region in glioma by methylation-specific PCR analysis. These results indicated that the four isoforms, including 14-3-3β, η, ζ, and σ, may play important roles in tumorigenesis of human glioma, which is probably used as potential biomarkers for diagnosis and targets for treatment of human gliomas in future.     

以序列特征值预测酶和非酶蛋白及内含肽

利用生物信息学快速准确鉴别酶、非酶蛋白及内含肽能极大提高实验效率,而测序数量的指数型增长使酶、非酶蛋白及内含肽的自动分类尤显重要。本文获取了同一性小于25%的序列共计3853条,采用Z标度的伪氨基酸组成和氨基酸组成分布提取序列特征值识别酶、非酶蛋白及内含肽。结果表明,该特征值提取方法经参数优化后,即当λ=5,w=0.15时,以支持向量机为分类器,其10倍交叉验证的精度可达81.3%,ROC曲线下面积为0.83;其精度高于其它方法0.5%到12.9%不等;独立样本测试的预测精度可达71.2%,ROC曲线下面积为0.782,其精度高于其它方法0.4%到6.4%不等,效果均优于其它常见的序列特征值方法。本文结果说明从序列出发判断其归属是可行的,3种不同功能的分子在序列特征上存在一定的差异,所建立的Z标度的伪氨基酸组成和氨基酸组成分布法可用于其它类似的生物信息学问题。建立了从序列出发预测酶、非酶蛋白及内含肽的新方法。     

新型核序列自相关函数用于非同源蛋白质结构类预测

从天然氨基酸的50个性质参数中经主成分分析得出1种新的氨基酸描述子:氨基酸特征性质得分.并在此基础上通过定义基于向量形式的自相关函数以及引入Mercer核技术将该函数运算空间进行非线性变换,最终提出了1种新的蛋白质序列表征方法:核序列自相关函数.采用该函数对632个已知晶体结构的非同源蛋白分类研究结果表明:KSACF能...     

低黄变和亲水性氨基聚硅氧烷的开发

概述了氨基聚硅氧烷的发展历程、特点及发展趋势,着重介绍了氨基聚硅氧烷的黄变机理,低黄变氨基聚硅氧烷、亲水性氨基聚硅氧烷的开发,以及氨基聚硅氧烷的生态环保性。