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1.
目的建立和优化用于检测大田软海绵酸(OA)的固定化蛋白质磷酸酶2A(PP2A)抑制率法。方法以分离提取的PP2A为材料,根据OA抑制PP2A酶活性的原理,建立用于检测OA的固定化PP2A酶抑制率法,并对最佳酶用量和反应体系参数等进行优化。结果最佳固定化PP2A酶蛋白量2μg、固定化配比为琼脂糖与PP2A酶蛋白量为1:1、p H值为8.4;采取4参数Logistic曲线法进行标准曲线拟合,曲线R2值达0.994,检测限为3.45μg/L,实际样品测定时具有良好的准确性和重复性。结论建立的固定化PP2A酶抑制率法有望作为低成本、操作简单的OA快速筛检方法推广应用。  相似文献   

2.
基于大田软海绵酸(OA)抑制蛋白质磷酸酶2A(PP2A)酶活性的原理,构建了固定化PP2A酶生物传感器,进一步对育温时间、p H和温度等影响电流响应的参数进行了优化,并以构建的传感器对OA进行了检测,采取4参数Logistic曲线法进行标准曲线拟合,曲线的R2值达0.9947,拟合度较好,OA的检测限为10.07μg/L,组间RSD为8.3%,在4℃放置7 d后,其响应电流为初始电流的87%,与HPLC方法相比,实际样品测定时具有良好的准确性与一致性,可以用于OA的快速检测。  相似文献   

3.
基于腹泻性贝毒素(Diarrhetic shellfish poisoning,DSP)的致腹泻性组分大田软海绵酸(okadaic acid,OA)及其衍生物鳍藻毒素(dinophysistoxins,DTXs)能抑制蛋白磷酸酶活性的特点,建立了快速测定贝类中DSP的磷酸酶抑制比色分析方法。采用对硝基苯磷酸二钠(p-nitrophenyl phosphate disodium,p-NPP)为底物,其与蛋白磷酸酶2A(protein phosphatase 2A,PP2A)反应生成的黄色水解产物在碱性条件下于405 nm波长处有强烈的吸收峰,根据吸光度值计算抑制剂的浓度。酶抑制法继承了小鼠生物法能建立剂量-效应关系的优势,直接反映毒素的相对毒性大小,测定的是DSP毒素致腹泻性成分的总量,以OA浓度计。本研究优化了样品前处理方法并考察了基质浓度的影响。方法的筛选检出限为80μg/kg。采用该方法进行加标回收实验,回收率在90.43%~118.52%范围内,相对标准偏差(RSD)为6.85%~13.93%。该方法操作简便、快捷,回收率高,重现性好,可作为快速筛查工具用于贝毒的日常监控。  相似文献   

4.
以海藻酸钠为载体,戊二醛为交联剂共固定化木瓜蛋白酶和中性蛋白酶,考察共固定化酶工艺的选择.水解芝麻蛋白的优化条件和共固定化酶的稳定性,芝麻蛋白水解物的复合氨基酸组成。结果表明.共固定化木瓜蛋白酶和中性蛋白酶的最佳条件为:海藻酸钠浓度3%,戊二醛浓度2.5%,氯化钙浓度0.2%,酶活力回收率为51.28%。水解芝麻蛋白的最佳条件为:固液比1:25,pH值6.0,温度60℃,时间7h,加酶量5%,氨基氮含量最高为20.65mg/g,共固定化酶重复使用6次.酶活力仍保持50%以上。芝麻蛋白水解物中15种氨基酸齐全。  相似文献   

5.
间接酶联免疫吸附检测克伦特罗条件优化   总被引:3,自引:0,他引:3  
优化间接酶联免疫吸附法的测定条件。采用间接测定克伦特罗抗血清效价和血清阻断率。采用0.5μg/mL的包被浓度最佳,2%卵清蛋白的封闭效果最好,抗血清工作浓度可选择为1∶1000,抑制曲线表明,小鼠抗血清中抗体特异性很好,呈现线性关系。相同条件下邻苯二胺(OPD)显色值高于四甲基联苯胺(TMB),OPD的浓度以及过氧化氢的添加量对保质期影响很大,抗体稀释液选用0.5%明胶较好。经过实验,建立了实用的检测条件。  相似文献   

6.
选择8种大孔树脂对磷脂酶A1进行固定化,结果表明,离子交换树脂D001的固定化效果最好,其优化的最佳条件为缓冲液pH5.0、酶添加量1.5mL/g、固定化时间4h,在该条件下获得的固定化酶活力为665.8U/g。将固定化酶用于菜籽油脱胶实验,经响应面优化确定最优脱胶条件为固定化酶添加量1.8g/kg、反应时间3.6h、反应温度51℃、反应pH5.5,在此条件下得到的脱胶油中磷含量为5.82mg/kg。将固定化酶重复脱胶5次后,仍保留初始酶活力的47.9%,脱胶油中磷含量为9.78mg/kg。  相似文献   

7.
以海藻酸钠微球为载体,使用包埋方法制备固定化蒜氨酸酶。优化了制备固定化酶的条件,并与游离酶对比研究了固定化酶的酶学性质。研究结果如下:(1)最优固定化条件为海藻酸钠质量浓度为25 g/L,CaCl2浓度为40 g/L,每克载体给酶量为573 U,固化2 h。(2)最佳反应时间为15 min,最适反应温度为45℃;固定化酶热稳定性明显高于游离酶。  相似文献   

8.
研究逆流超声预处理大米蛋白对其碱性蛋白酶酶解制备血管紧张素转换酶(Angiotensin-I Converting Enzyme,ACE)抑制肽的影响。首先从米渣中提取大米蛋白,以ACE抑制率为主要指标,水解度为辅助指标,运用单因素逐级优化法对酶解反应的底物浓度、时间、温度、加酶量和pH进行参数优化,在此基础上筛选逆流超声模式的最佳超声参数。结果表明最佳酶解参数为底物浓度30 g/L、加酶量(E/S)7.5%、温度50 ℃、pH8.5和酶解时间60 min,此时酶解产物ACE抑制率为45.59%,水解度为21.49%。最佳超声参数为超声频率20 kHz、功率密度170 W/L、时间12.5 min。此时酶解液ACE抑制率达72.24%,水解度为21.64%,相较于未超声组ACE抑制率提高了57.42%,相较于传统超声组,ACE抑制率提高了11.36%。结果表明逆流超声波辅助酶解法能有效提高酶解效率、减少能耗、促进ACE抑制肽制备。  相似文献   

9.
选择合适的蛋白质水解酶是制备高活性抗氧化肽的关键。以小麦胚芽清蛋白为原料,酶解产物的DPPH自由基清除率以及ORAC值为指标,从4种蛋白酶(胰蛋白酶、木瓜蛋白酶、中性蛋白酶和碱性蛋白酶)中,筛选得出中性蛋白酶为最佳用酶。然后通过响应面法对中性蛋白酶酶解工艺条件进行了优化。结果表明,中性蛋白酶酶解麦胚清蛋白的最佳酶解参数为:底物浓度2.4%、加酶量5 900 U/g、酶解p H 7.04、酶解温度55℃、酶解时间4 h。此酶解条件下,其1 mg/m L酶解产物的DPPH自由基清除率为65.93%,100μg/m L酶解产物的ORAC值为1 291.32μmol Trolox当量/g多肽。  相似文献   

10.
为了研究鱿鱼碎肉通过固定化双酶水解法制备高F值寡肽的工艺,以蛋白质水解度为指标,通过单因素和正交试验确定固定化胃蛋白酶和固定化风味酶的最佳酶解条件。第1步采用固定化胃蛋白酶,其最佳酶解条件是:料水比1∶5、加酶量26.83 U/g鱿鱼碎肉、水解时间5 h、水解温度55℃;第2步采用固定化风味酶,其最佳酶解条件是:加酶量1 692 U/g鱿鱼碎肉、pH 7.0、水解温度55℃、水解时间3 h;两步酶解后的总水解度为(32.09±0.58)%,OD_(280)为0.238±0.001。酶解液经多级活性炭串联吸附脱除芳香族氨基酸后,支链氨基酸和芳香族氨基酸的比值(F值)大于20。鱿鱼碎肉经固定化胃蛋白酶和固定化风味蛋白酶分步水解后,活性炭串联吸附脱芳后可制备高F值寡肽。  相似文献   

11.
Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.  相似文献   

12.
An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.  相似文献   

13.
The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.  相似文献   

14.
The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.  相似文献   

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This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.  相似文献   

18.
Capillary electrophoresis (CE) and polarized light microscopy (PLM) were utilized in the detection of the adulteration of locust bean gum with guar gum. For CE analyses, standards of locust bean and guar gums were extracted with 30% CH3CN, removing the residual proteins from the gum matrix. A 8.75 mM NaH2PO4-20.6 mM Na2B4O7 buffer, pH 9, was used to separate these proteins and to identify marker proteins that were present in the guar gum. These markers did not co-migrate with components in the extracts of mechanically processed locust bean gum, and are used as indicators of adulteration. Using PLM with toluidine blue and iodine staining techniques, unadulterated locust bean gum samples were distinguished from mixed samples through the differential staining of components in locust bean versus guar and tara gums. These experiments in the use of CE and PLM provide orthogonal and complementary methods for the verification of 'true' positives and the elimination of 'false' positives.  相似文献   

19.
<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the  相似文献   

20.
《印刷工业》2014,(11):95-95
According to Printing and Printing Equipment Industries Association of China(PEIAC)'s statistics to the plate manufucturer in China, in 2013, the actual offset plate production has reached 346 million square meters in China. Among them, the CTP production volume was 245 million square meters, up by 11% than that of last year; the total sales of the CTP plate was 239 million square meters, up by 13%.  相似文献   

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