Total and polar lipids in soybean protein meals

Soybean protein meals obtained by various oil extraction methods have different neutral oil content, and they may contain differnet amounts of polar lipids. Three soy protein meals obtained by different processing methods were extracted by two solvents consecutively, chloroform/methanol (2:1, vol/vol) and water-saturated butanol, for total lipid analysis. The organic flour (i.e., ground soybean) containted 15.52% total lipids; the high protein dispersibility index flour from extrusion-expelling processing and the white flour from conventional solvent extraction contained 11.20 and 1.84% total lipids, respectively. Organic flour contained more polar lipids than the other two protein meals on a dry-weight meal basis. Chloroform/methanol extracted most of the lipid from the meals, whereas water-saturated butanol resulted in an extract with more polar lipids than that from chloroform/methanol extraction.     

二氰二胺和磷酸对大豆蛋白纤维的阻燃研究

本文分别用二氰二胺、磷酸以及二氰二胺和磷酸协同体系对大豆蛋白纤维(天鹅绒,38%大豆蛋白纤维/38%棉/24%涤纶)进行阻燃整理(主要对天鹅绒制品中的大豆蛋白纤维的处理),通过极限氧指数、剩炭率、热分析和扫描电子显微镜等分析方法对其阻燃性能进行研究,并用Broido方程计算其热降解活化能的变化。结果表明:与未经阻燃处理的大豆蛋白纤维相比,阻燃大豆蛋白纤维的极限氧指数、剩炭率均有所增加;热降解起始温度降低;热降解活化能减小;剩炭较为膨胀,其中经二氰二胺和磷酸协同体系处理后的样品阻燃效果最佳。     

大豆分离蛋白及其与丙烯酸接枝产物在不同pH值水相中的动态光散射研究

利用动态光散射技术,研究了大豆分离蛋白及其与丙烯酸接枝共聚物在水相体系中对pH值的响应性。结果发现,大豆分离蛋白和接枝产物对水相pH值都具有很高的响应性。大豆分离蛋白平均流体力学半径在等电点附近(pH=4~5)达到最大值。接枝率为27.5%的丙烯酸的接枝共聚物的平均流体力学半径在pH为2~3范围内最大。随着接枝率增加,丙烯酸的接枝共聚物在水相体系中的溶解性能越好。对接枝产物不同pH值水溶液进行研究具有很大的理论指导意义。     

Single antibody domains as small recognition units: design and in vitro antigen selection of camelized, human VH domains with improved protein stability

Folding stabilities of camelized human antibody VH domains werestudied through the determination of their melting points inthermodenaturation experiments. The melting point of a VH domainoriginating from a synthetic library of human VHs, which hadbeen optimized for the use as small recognition units throughthe mimicking of camelid antibody heavy chains occurring naturallywithout light chain, was 56.6C compared with 71.2C of theoriginal human VH. Its stability was improved (melting point61.6C) through three mutations to mimic camelid VHs even further:Va137 was replaced by phenylalanine and two cysteines were introducedat positions 33 and 100b. The resulting VH folded properly andformed a second intradomain disulphide between the extra cysteines.The new mutations were then built constitutively into a phage-displayVH library, from which antigen-specific VHs were selected. Twowere analysed for stability with melting points of 72.6 and75.3C. Thus secondary camelization enabled the isolation ofVHs with improved folding stabilities exceeding even that ofthe original human VH. This indicates an effect on folding stabilityfor some mutations specific in the light chain lacking camelidheavy chains.     

A single Fc binding domain-alkaline phosphatase gene fusion expresses a protein with both IgG binding ability and alkaline phosphatase enzymatic activity

A recombinant gene fusion was created and cloned using a previouslyconstructed gene encoding a monodomain IgG Fc binding proteinand the gene coding for bacterial alkaline phosphatase. Theconstruct was able to express and secrete a fusion protein thatexhibited both IgG binding and alkaline phosphatase enzymaticactivities. Greater than 60% of the protein demonstrating bothbiological activities was detected from periplasmic space preparations.Nanogram concentrations of the Fc binding-alkaline phosphatasefusion protein allowed primary IgG antibody detection withoutthe use of conjugated secondary antibodies. Removal of the domaincoding for alkaline phosphatase resulted in decreased resistanceof the protein to proteolytic degradation and the loss of IgGFc binding ability. Using affinity-purified fusion protein,the specificity of binding to IgG, IgM and IgA was examined;binding was strong to IgG and barely detectable against IgMor IgA. Affinity for binding of the fusion protein to IgG (k_d= 6.7 x10^-8 M) was determined to be equal to or greater thanpreviously reported for protein A.     

Synthesis, in vitro cytotoxicity, and interaction with DNA of platinum(II) complexes with N-monocycloalkyl derivatives of 1R,2R-diaminocyclohexane as carrier ligands

A series of platinum(II) complexes with N-monocyclopentyl/cyclohexyl derivatives of 1R,2R-diaminocyclohexane as carrier ligands and dicarboxylate anions as leaving groups were synthesized and characterized. All complexes were characterized by elemental analysis, IR, (1)H NMR, and (13)C NMR spectroscopy, as well as ESIMS. The in vitro antiproliferative activities were tested by MTT assay against four human cancer cell lines; breast carcinoma (MCF-7) and colon cancer (HCT-116) cells were particularly sensitive, especially to complexes 1f (IC(50) =9.81 and 1.49 μM) and 2f (IC(50) =4.59 and 0.36 μM). Flow cytometry indicated that representative compounds exert cytotoxicity toward MCF-7 and HCT-116 cells through induction of apoptosis and blockage of cell-cycle progression in the S phase, similar to cisplatin. The interaction between the platinum(II) complexes and pET22b plasmid DNA was observed by agarose gel electrophoresis, revealing that complex 2f has the capacity to distort plasmid DNA in a manner distinct from that of oxaliplatin.     

Directed evolution of a type I antifreeze protein expressed in Escherichia coli with sodium chloride as selective pressure and its effect on antifreeze tolerance

Both freezing tolerance and NaCI tolerance are improved whenantifreeze proteins are expressed as fusion proteins with twodomains of staphylococcal protein A (SPA) in Escherichia coli.To characterize these properties further we created a randomlymutated expression library in E.coli, based on the winter flounderantifreeze protein HPLC-8 component gene. Low-fidelity PCR productsof this gene were fused to the spa gene encoding two domainsof the SPA. The library was screened for enhanced NaCl toleranceand four clones were selected. The freezing tolerance of eachof the selected clones was enhanced to varying extents. DNAsequencing of the isolated mutants revealed that the amphiphilicproperties of the native antifreeze protein were essentiallyconserved. Furthermore, by studying the primary sequence ofthe randomly mutated clones, in comparison with the degree offreezing tolerance, we have identified clues which help in understandingthe relationship between salt and freezing tolerance.