Quantification of secondary structure prediction improvement using multiple alignments

The use of multiple sequence alignments for secondary structurepredictions is analysed. Seven different protein families, containingonly sequences of known structure, were considered to providea range of alignment and prediction conditions. Using alignmentsobtained by spatial superposition of main chain atoms in knowntertiary protein structures allowed a mean of 8% in secondarystructure prediction accuracy, when compared to those obtainedfrom the individual sequences. Substitution of these alignmentsby those determined directly from an automated sequence alignmentalgorithm showed variations in the prediction accuracy whichcorrelated with the quality of the multiple alignments and distanceof the primary sequence. Secondary structure predictions canbe reliably improved using alignments from an automatic alignmentprocedure with a mean increase of 6.87percnt;, giving an overallprediction accuracy of 68.5%, if there is a minimum of 25% sequenceidentity between all sequences in a family.     

大豆蛋白/粘胶共混纤维的结构与性能

采用湿法纺丝制备大豆蛋白/粘胶共混纤维,分析测试了共混纤维的结构形态与物理机械性能的关系,并与其他类型的蛋白质改性纤维进行了比较。实验结果表明共混纤维的力学性能与蛋白质比例有关,随着蛋白质质量分数的增加,纤维的强度降低;共混纤维的截面形状和黏胶纤维相似,但表面沟槽更为明显。     

酸、碱溶液对脱脂蚕蛹的解剖结构影响

将脱脂蚕蛹分别置于清水、1%盐酸溶液和1%氢氧化钠溶液中,100℃浸泡处理20 min,采用电子光学显微分析技术观察脱脂蚕蛹的解剖结构。结果表明:①清水浸泡,蛋白质、甲壳素膨胀;②盐酸溶液浸泡,在蛋白质、甲壳素膨胀的同时,有蛋白的部分分解;③氢氧化钠溶液浸泡,蛋白质、甲壳素膨胀,蛋白质溶解,并伴有部分蛋白的分解。碱对蛋白层与甲壳层的层间有劈开作用。碱液能实现蛋白层与甲壳层的剥离。     

Association of seed size with genotypic variation in the chemical constituents of soybeans

Ten soybean genotypes grown in 1992 with seed size ranging from 7.6 to 30.3 g/100 seeds and maturity group V or VI were selected and tested for oil and protein content and for fatty acid composition. In these germplasm, protein varied from 39.5 to 50.2%, oil, 16.3 to 21.6%, and protein plus oil, 59.7 to 67.5%. Percentages of individual fatty acids relative to total fatty acids varied as follows: palmitic, 11.0 to 12.8; stearic, 3.2 to 4.7; oleic, 17.6 to 24.2; linoleic, 51.1 to 56.3 and linolenic, 6.9 to 10.0. Seed size showed no significant correlations with individual saturated fatty acids, protein or oil content. However, significant correlations were found between seed size and individual unsaturated fatty acids: positive with oleic, and negative with linoleic and linolenic. Oil and protein content were negatively correlated with each other. Among the major fatty acids, only the unsaturated were significantly correlated with each other: negative between oleic and linoleic or linolenic, and positive between linoleic and linolenic. A subsequent study with soybeans grown in 1993 generally confirmed these findings. Variation in relative percentages of unsaturated fatty acids andr values for most pairs of relationships were even higher than those obtained from the 1992 crop. Presented at the 85th AOCS Annual Meeting and Expo, Atlanta, Georgia, May 8–12, 1994.     

长春新碱治疗糖尿病肾病大鼠的实验研究

目的验证长春新碱对糖尿病肾病大鼠的治疗作用。方法用链脲佐菌素(STZ)诱导大鼠糖尿病模型。将模型大鼠分为治疗组与非治疗组,治疗组给予长春新碱(VCR)0.2 mg/kg,尾静脉注射,每周2次,观察给药后大鼠血糖、尿蛋白、肾功能、肾重,体重等值的改变以及肾脏病理的改善情况。结果 治疗组大鼠尿蛋白明显减少,肾重/体重低于非治疗组。光镜下观察治疗组肾脏病理学变化情况有明显改善。结论长春新碱可降低糖尿病肾病大鼠的尿蛋白并改善糖尿病肾病早期病理损害。     

The influence of Glu44 and Glu56 of cytochrome b5 on the protein structure and interaction with cytochrome c

The gene encoding trypsin-solubilized bovine liver microsomalcytochrome b₅ (82 residues in length) has been mutated, in whichthe codons of Glu44 and Glu56 were changed to those of Ala.The mutated genes were expressed in Escherichia coli successfullyand three mutant proteins (E44A, E56A and E44/56A) were obtained.The UV-visible, CD and ¹H NMR spectra of proteins have beenstudied. The results show that the mutagenesis at surface residuesdoes not alter the secondary and tertiary structures of cytochromeb₅ significantly. The interactions between recombinant cytochromeb₅ and its mutants with cytochrome c were studied by using opticaldifference spectra. The results demonstrated that both Glu44and Glu56 of cytochrome b₅ participate in the formation of acomplex between cytochrome b₅ and cytochrome c.     

妊娠相关血浆蛋白A的分离及纯化

采用人胎盘血为原料,利用Sephadex G-200,DEAE-Sephadex A-50层析,Sepharose 4B反相免疫亲和层析技术,获得妊娠相关血浆蛋白A(PAPP-A)纯品,经8.0％聚丙烯酰胺凝胶电泳、免疫电泳、双向免疫扩散证明,所提取的PAPP-A纯品为单一成分。免疫家兔获得抗血清,其效价在1:16以上。     

Chromatographic performance of monodisperse–macroporous particles produced by “modified seeded polymerization.” I: Effect of monomer/seed latex ratio

In this study, the monodisperse–macroporous particles produced by a relatively new polymerization protocol, the so‐called, “modified seeded polymerization,” were used as column‐packing material in the reversed phase chromatography (RPC) of proteins. The particles were synthesized in the form of styrene‐divinylbenzene copolymer approximately 7.5 μm in size. In the first stage of the synthesis, the monodisperse polystyrene particles 4.4 μm in size were obtained by dispersion polymerization and used as the “seed latex.” The seed particles were swollen by a low‐molecular‐weight organic agent and then by a monomer mixture. The monodisperse–macroporous particles were obtained by the polymerization of monomer mixture in the seed particles. In the proposed polymerization protocol, the number of successive swelling stages was reduced with respect to the present techniques by the use of sufficiently large particles with an appropriate average molecular weight as the seed latex. A series of particles with different porosity properties was obtained by varying the monomer/seed latex ratio. The separation behavior of HPLC columns including the produced particles as packing material was investigated in the RPC mode using a protein mixture including albumin, lysozyme, cytochrome c, and ribonuclease A. The chromatograms were obtained with different flow rates under an acetonitrile–water gradient. The theoretical plate number increased and chromatograms with higher resolutions were obtained with the particles produced by using a lower monomer/seed latex ratio. The separation ability of the column could be protected over a wide range of flow rates (i.e., 0.5–3 mL/min) with most of the materials tested. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 607–618, 2004     

重组B7-H1IgV融合蛋白的表达、纯化及活性鉴定

目的以B7-H1为靶点,研制肿瘤免疫治疗蛋白疫苗。方法将人B7-H1胞外片段IgV区基因插入pQE-30原核表达载体,转化大肠杆菌,经IPTG诱导表达。Ni2+-NTA亲和层析纯化蛋白,Westernblot鉴定。用纯化的rhB7-H1IgV蛋白免疫昆明小鼠,经ELISA、流式细胞术、免疫组化技术和CDC试验测定融合蛋白及其抗血清的生物学活性。结果所构建的pQE-30-TT-B7-H1IgV表达载体,能稳定表达rhB7-H1IgV蛋白,经纯化后免疫昆明小鼠,可获得高滴度抗B7-H1抗血清。经流式细胞术和免疫组化检测显示,其抗血清可与HT-29/B7-H1+及SP2/0肿瘤细胞结合,且在CDC试验中,可依赖补体杀伤HT-29/B7-H1+及SP2/0肿瘤细胞。结论rhB7-H1IgV融合蛋白不仅可引发小鼠体液免疫应答,而且其抗体还能与表达B7-H1的肿瘤细胞相结合,并介导补体依赖的体外杀伤作用。