不同方法收集番茄叶挥发性物质的GC/MS指纹图谱比较

以番茄（Lycopersicon esculentum）叶为材料．分别采用溶媒萃取、水蒸气蒸馏、气体吸附法收集挥发性物质;气相色谱-质谱联用技术分离鉴定挥发组分。结果表明,3种收集方式共获得19种挥发性组分．其中的14种组分相同．且多为主要组分。水蒸气蒸馏法获得的挥发性物质总含量最高,为27．13μg FW;其次是气体吸附法．为23．38μg FW,溶媒萃取法获得的最少,仅为12．40μg FW。溶媒萃取法共获得15种挥发组分．含量最高的组分为β-水芹烯。水蒸气蒸馏法获得18种组分．含量最高的组分为（E）-2-己烯醛。气体吸附法获得17种组分．含量最高的组分为（E）-2-己烯醛。不同方法所获各组分的相对含量和绝对含量均不同．可根据研究目的综合分析运用。     

薏苡仁蛋白质组分研究

目的：对药食两用功能的薏苡仁蛋白质四类组分和氨基酸含量进行分析。方法：采用旋光法、索氏提取法、烘干法、马弗炉法分别进行淀粉、粗脂肪、水分和灰分的测定;采用顺序抽提法依次进行清蛋白、球蛋白、醇溶蛋白和谷蛋白的提取,用Brandford和凯式定氮法进行蛋白质含量分析;采用氨基酸分析仪进行氨基酸含量测定。结果：薏苡仁总蛋白含量为14．17％,其中清蛋白、球蛋白、醇溶蛋白和谷蛋白含量分别为0．20、0．88、6．34和5．30mg／100mg鲜重,分别占总蛋白质含量的1．43％、6．20％、44．74％和37．38％;薏苡仁粉经酸水解后共检测到15种氨基酸,除Trp外,人体必需氨基酸和半必需氨基酸均有检测到;各氨基酸含量也存在着差异,含量最高的为Glu（3．59mg／100mg）,含量最低的为Met（0．17mg／100mg）。结论：薏苡仁蛋白中醇溶蛋白和谷蛋白含量较丰富,为今后进一步开发薏苡仁功能食品提供了理论数据。     

酶浸提取方法对士的宁产率的影响

目的：研究了纤维素酶在提取生物碱过程中的应用。方法：采用酶浸法和氯仿法两种不同的工艺提取马钱子生物总碱,高效液相色谱法（HPLC）测定了马钱子生物总碱中士的宁的含量。结果：酶浸法提取士的宁和氯仿法提取士的宁的含量分别为1．83％、1．32％;酶浸法和氯仿法提取马钱子生物总碱的产率分别为：2．85％、1．86％。     

三七叶甙含量测定方法比较

本文报道了采用（１）溴加成法,（２）分光光度比色法测定三七叶甙含量的方法并对进行比较。结果（１）法所测得结果比（２）法高７．１％￣１９．７％,其标准偏差分别为３．２６（％）和０．９０（％）。认为分光光度比色法测定三七叶甙含量较佳。     

木瓜中齐墩果酸的提取分离及含量测定

有渗漉法对木瓜中的齐墩果酸进行了提取,用层析柱法对提取物进行分离,方法较简便。并以标准品作对照,采用薄层比色法对其进行含量测定,该法操作简便,结果稳定。经测定木瓜中的游离齐墩果酸的含量为0．935％。     

不同产地丹参中有效成分的含量比较

用索氏提取法提取丹参的水溶性有效成分,用冷浸法提取丹参的酯溶性有效成分,以HPLC法测得的丹参素、丹参酮ⅡA和原儿茶醛含量为考察指标,对全国几个著名的丹参药材基地种植的丹参中丹参素、原儿茶醛和丹参酮ⅡA的含量及其稳定性进行了比较。不同产地丹参有效成分含量有较大差异。河南和四川产的丹参中酚酸类化合物含量最高,每克药材丹参素含量分别为19．79mg和20．35mg,每克药材原儿茶醛含量分别为5．58mg和4．35mg,贵州铜仁地区产的丹参丹参酮ⅡA含量最高,每克药材达0．4mg。     

用火箭电泳法检测人用狂犬病疫苗半成品抗原含量初探

用火箭电泳法（ＲＩＥ）检测了５批ａＧ株地鼠肾细胞人用狂犬病疫苗半成品（未加吸附剂）的抗原含量。结果表明,ＲＩＥ法快速、简便、准确。峰高与浓度的线性相关系数ｒ〉０．９９５０,待检疫苗与标准品的剂量反应曲线高度一致,试验的灵敏度为０．１５ＩＵ／ｍｌ,重复性好,５次结果的变异系统ＣＶ％≤５．７４％。因此,ＲＩＥ法有可能作为检测狂犬病疫苗半成品抗原含量的适宜方法     

赤霉酸含量紫外吸收测定法的改进

目的：用紫外法专一性地测定赤霉酸含量。方法：加入１ｍｏｌ／Ｌ氢氧化钠溶液终止赤霉酸在酸性条件下的降解,测定降解产生的赤霉烯酸的紫外吸收值进而确定赤霉酸的含量。结果：吸光度与ＧＡ３含量在一定浓度范围内有良好的线性关系,γ＝０．９９７８,ＲＳＤ＝０．４５％,与原有的Ｈｏｌｂｒｏｏｋ方法相比,测定结果无显著性差异（Ｐ＞０．０５）。该方法快速、易行且重复性良好     

新疆阿魏中总黄酮的提取分离及含量测定

以芦丁为对照品,NaNO2-AlCl3-NaOH体系为显色剂分光光度法测定新疆阿魏的总黄酮类含量。通过回流法和超声法提取新疆阿魏中的总黄酮,比较两种提取方法,从而得到最佳的提取方法,超声法是合适的提取方法。确定了提取总黄酮的适当溶剂、时间和显色剂用量。建立了芦丁浓度-吸光度关系的回归方程为A=9．2500C-0．0193,r=0．9993。平均回收率为98．73％。RSD为1．04％（n=6）。方法简单、可行、重现性好。     

生长激素和催乳素放射免疫测定法的建立与应用

目的：建立测定大鼠垂体和血浆中生长激素（GH）和催乳素（PRL）含量的高特异性、高灵敏度的双抗放射免疫测定（RIA）法;研究急性低氧对垂体激素GH和PRL的作用。方法：用氯胺－T法进行抗原放射性碘标记;采用平衡饱和加样程序的双抗RIA法测定。结果：用该方法测定急性低氧（0．5h）时血浆和垂体GH和PRL含量,7km低氧,垂体GH含量明显升高（P＜0．05）,血浆则相反;7km低氧,明显降低垂体和血浆PRL含量（P＜0．01）;而5km低氧对GH和PRL的作用与对照组比无统计学差异。结论：本双抗RIA法具有高特异性、高灵敏度及简便易行等特性;用该法测定提示急性低氧可抑制大鼠GH和PRL的分泌。     

Sequence‐specific determination of protein and peptide concentrations by absorbance at 205 nm

Quantitative studies in molecular and structural biology generally require accurate and precise determination of protein concentrations, preferably via a method that is both quick and straightforward to perform. The measurement of ultraviolet absorbance at 280 nm has proven especially useful, since the molar absorptivity (extinction coefficient) at 280 nm can be predicted directly from a protein sequence. This method, however, is only applicable to proteins that contain tryptophan or tyrosine residues. Absorbance at 205 nm, among other wavelengths, has been used as an alternative, although generally using absorptivity values that have to be uniquely calibrated for each protein, or otherwise only roughly estimated. Here, we propose and validate a method for predicting the molar absorptivity of a protein or peptide at 205 nm directly from its amino acid sequence, allowing one to accurately determine the concentrations of proteins that do not contain tyrosine or tryptophan residues. This method is simple to implement, requires no calibration, and should be suitable for a wide range of proteins and peptides.     

A miniaturized technique for assessing protein thermodynamics and function using fast determination of quantitative cysteine reactivity

Protein thermodynamic stability is a fundamental physical characteristic that determines biological function. Furthermore, alteration of thermodynamic stability by macromolecular interactions or biochemical modifications is a powerful tool for assessing the relationship between protein structure, stability, and biological function. High-throughput approaches for quantifying protein stability are beginning to emerge that enable thermodynamic measurements on small amounts of material, in short periods of time, and using readily accessible instrumentation. Here we present such a method, fast quantitative cysteine reactivity, which exploits the linkage between protein stability, sidechain protection by protein structure, and structural dynamics to characterize the thermodynamic and kinetic properties of proteins. In this approach, the reaction of a protected cysteine and thiol-reactive fluorogenic indicator is monitored over a gradient of temperatures after a short incubation time. These labeling data can be used to determine the midpoint of thermal unfolding, measure the temperature dependence of protein stability, quantify ligand-binding affinity, and, under certain conditions, estimate folding rate constants. Here, we demonstrate the fQCR method by characterizing these thermodynamic and kinetic properties for variants of Staphylococcal nuclease and E. coli ribose-binding protein engineered to contain single, protected cysteines. These straightforward, information-rich experiments are likely to find applications in protein engineering and functional genomics.     

The use of lectin microarray for assessing glycosylation of therapeutic proteins

Glycans or carbohydrates attached to therapeutic glycoproteins can directly affect product quality, safety and efficacy, and therefore must be adequately analyzed and controlled throughout product life cycles. However, the complexity of protein glycosylation poses a daunting analytical challenge. In this study, we evaluated the utility of a lectin microarray for assessing protein glycans. Using commercial lectin chips, which contain 45 lectins toward distinct glycan structures, we were able to determine the lectin binding patterns of a panel of 15 therapeutic proteins, including 8 monoclonal antibodies. Lectin binding signals were analyzed to generate glycan profiles that were generally consistent with the known glycan patterns for these glycoproteins. In particular, the lectin-based microarray was found to be highly sensitive to variations in the terminal carbohydrate structures such as galactose versus sialic acid epitopes. These data suggest that lectin microarray could be used for screening glycan patterns of therapeutic glycoproteins.     

The fragile X mental retardation protein interacts with U-rich RNAs in a yeast three-hybrid system

We recently identified several ESTs that bind to the fragile X mental retardation protein (FMRP) in vitro. To determine whether they interacted in vivo we performed three-hybrid screens in a Saccharomyces cerevisiae histidine auxotroph. We demonstrate that two of the ESTs support growth on histidine and transduce beta-galactosidase activity when co-expressed with FMRP under selective growth conditions. In contrast, the iron response element (IRE) RNA does not. Likewise, the ESTs do not support growth or transduce beta-galactosidase activity when co-expressed with the iron response element binding protein (IRP). Each EST is relatively small and has 40% identity with a sequence in FMR1 mRNA harboring FMRP binding determinants. Interestingly, while neither the ESTs contain a G-quartet structural motif they do contain U-rich sequences that are found in mRNA with demonstrated in vitro binding and in vivo association with FMRP. This indicates that U-rich elements comprise another motif recognized by FMRP.     

The betaII isotype of tubulin is present in the cell nuclei of a variety of cancers

Tubulin, the subunit protein of microtubules, has generally been thought to be exclusively a cytoplasmic protein in higher eukaryotes. We have previously shown that cultured rat kidney mesangial cells contain the betaII isotype of tubulin in their nuclei in the form of an alphabetaII dimer [Walss et al., 1999: Cell Motil. Cytoskeleton 42:274-284, 1999]. More recently, we examined a variety of cancerous and non-cancerous cell lines and found betaII in the nuclei of all of the former and only a few of the latter (Walss-Bass et al., 2002: Cell Tissue Res. 308:215-223]. In order to determine if betaII-tubulin occurs in the nuclei of actual cancers as well as in cancer cell lines, we used the immunoperoxidase method to look for nuclear betaII in a variety of tumors excised from 201 patients. We found that 75% of these tumors contain betaII in their nuclei. Distribution of nuclear betaII was highly dependent on the type of cancer, with 100% of the colon and prostate cancers, but only 19% of the skin tumors, having nuclear betaII. Nuclear betaII was particularly marked in tumors of epithelial origin, of which 83% showed nuclear betaII, in contrast to 54% in tumors of non-epithelial origin. In many cases, betaII staining occurred very strongly in the nuclei and not in the cytoplasm; in other cases, betaII was present in both. In many cases, particularly metastases, otherwise normal cells adjacent to the tumor also showed nuclear betaII, suggesting that cancer cells may influence nearby cells to synthesize betaII and localize it to their nuclei. Our results have implications for the diagnosis, biology, and chemotherapy of cancer.     

The dynamics of protein body formation in developing wheat grain

Wheat is a major source of protein in the diets of humans and livestock but we know little about the mechanisms that determine the patterns of protein synthesis in the developing endosperm. We have used a combination of enrichment with ¹⁵N glutamine and NanoSIMS imaging to establish that the substrate required for protein synthesis is transported radially from its point of entrance in the endosperm cavity across the starchy endosperm tissues, before becoming concentrated in the cells immediately below the aleurone layer. This transport occurs continuously during grain development but may be slower in the later stages. Although older starchy endosperm cells tend to contain larger protein deposits formed by the fusion of small protein bodies, small highly enriched protein bodies may also be present in the same cells. This shows a continuous process of protein body initiation, in both older and younger starchy endosperm cells and in all regions of the tissue. Immunolabeling with specific antibodies shows that the patterns of enrichment are not related to the contents of gluten proteins in the protein bodies. In addition to providing new information on the dynamics of protein deposition, the study demonstrates the wider utility of NanoSIMS and isotope labelling for studying complex developmental processes in plant tissues.     

The aspartic proteinase of barley is a vacuolar enzyme that processes probarley lectin in vitro.

Previous work suggested that the aspartic proteinase from Hordeum vulgare (HvAP) would be a vacuolar protein in plant cells. Based on N-terminal sequencing we show that the in vitro-translated protein was translocated into the lumen of microsomal membranes, causing a concomitant removal of 25 amino acid residues from the protein. Vacuoles were purified from barley leaf protoplasts and were shown to contain all of the aspartic proteinase activity found in the protoplasts. This vacuolar localization of HvAP was confirmed with immunocytochemical electron microscopy using antibodies to HvAP in both barley leaf and root cells. In an attempt to discern a function for this protease, we investigated the ability of HvAP to process the C-terminal proregion of barley lectin (BL) in vitro. Prolectin (proBL), expressed in bacteria, was processed rapidly when HvAP was added. Using several means, we were able to determine that 13 amino acid residues at the C terminus of proBL were cleaved off, whereas the N terminus stayed intact during this incubation. Immunohistochemical electron microscopy showed that HvAP and BL are co-localized in the root cells of developing embryos and germinating seedlings. Thus, we propose that the vacuolar HvAP participates in processing the C terminus of BL.     

Study of adsorption of Influenza virus matrix protein M1 on lipid membranes by the technique of fluorescent probes

Matrix protein M1 of Influenza virus, which forms its inner scaffold, is the most abundant amongst viral proteins. Functions of M1 protein are highly diverse, as it has to ensure both the entry of the viral genetic material into the cytoplasm of the infected cell and the assembly of new viral particles for multiplication of infection. In all these processes matrix protein interacts with lipid membranes–either viral external lipid envelope or plasma membrane of a virus-infected cell. However, molecular mechanisms of such interactions are still unclear. In this work, we used the method of fluorescent probes on the example of 1-anilinonaphthalene- 8-sulfonate to determine components of the lipid bilayer required for binding of the M1 protein to the membrane, as well as possible orientations of the protein relative to the lipid membrane. We found that for the adsorption of matrix protein M1 lipid bilayer had to contain phosphatidylserines, while neither phosphatidylethanolamine nor cholesterol promoted protein binding to the membrane. Furthermore, our data suggest that M1 protein binds negatively charged lipid bilayer by positively charged amino acids exhibiting outward anionic sites.     

Plasma membrane lipid order of leukemic and normal immature avian erythroid cells

Mammalian erythroblasts and their leukemic counterparts contain characteristic disordered regions of plasma membrane identified as putative membrane protein collection sites. In order to determine whether erythroid cells which do not enucleate contain homologous membrane domains, immature avian erythroid precursor cells and avian erythroleukemic cells were examined using merocyanine 540 (MC540), a fluorescent dye whose binding is sensitive to the packing of membrane lipids. Results were found to contrast with previous studies of the murine equivalents of these cells. In birds, normal erythroid precursors, including basophilic erythroblasts from the bone marrow and spleen of anemic animals, contained no detectable (less than 0.1%) cells which were stained by the dye. But cells from chicks infected with avian erythroblastosis virus (AEV) did stain. Considering the pattern of staining observed on AEV-erythroblasts relative to other leukemic and normal phenotypes, however, we conclude that neither normal nor leukemic avian erythroid cells contain a functional equivalent to the membrane protein collection sites found on their mammalian counterparts.     

The protein that binds to DNA base J in trypanosomatids has features of a thymidine hydroxylase

Trypanosomatids contain an unusual DNA base J (beta-d-glucosylhydroxymethyluracil), which replaces a fraction of thymine in telomeric and other DNA repeats. To determine the function of base J, we have searched for enzymes that catalyze J biosynthesis. We present evidence that a protein that binds to J in DNA, the J-binding protein 1 (JBP1), may also catalyze the first step in J biosynthesis, the conversion of thymine in DNA into hydroxymethyluracil. We show that JBP1 belongs to the family of Fe(2+) and 2-oxoglutarate-dependent dioxygenases and that replacement of conserved residues putatively involved in Fe(2+) and 2-oxoglutarate-binding inactivates the ability of JBP1 to contribute to J synthesis without affecting its ability to bind to J-DNA. We propose that JBP1 is a thymidine hydroxylase responsible for the local amplification of J inserted by JBP2, another putative thymidine hydroxylase.