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1.
农药残留快速检测固定化酶片的研究   总被引:3,自引:0,他引:3  
许娟  李建科  牛乐 《食品科学》2008,29(6):268-272
采用硝酸纤维素膜(Nc)和植物酯酶研究了农药残留快速检测固定化酶片.通过对酶用量、戊二醛浓度、牛血清白蛋白浓度、固定化pH值和温度的参数优化,建立了NC膜固定化植物酯酶的方法,即:20μl游离酶,0.05%戊二醛2μl,0.5%牛血清白蛋白15μl,pH7.0缓冲液体系,4℃下固定8h.对游离酶和固定化酶的特性进行了比较,发现固定化植物酯酶对底物的最适反应温度为35℃,比游离酶提高了5℃;最适pH为8.0,比游离酶提高了0.5个pH单位.游离酶和固定化酶对四种农药(敌敌畏、灭多威、氧乐果、久效磷)的敏感性进行了比较,发现固定化酶对四种农药敏感性都较游离酶有所提高,固定化酶更适合于农药的快速检测.  相似文献   

2.
利用农药对酯酶活力的抑制反应,分别采用游离的和固定化的鸡肝酯酶,对不同浓度的敌敌畏、敌百虫、马拉硫磷和西维因进行了测定。结果发现,在低浓度时,农药浓度的对数值与其对应的酶活抑制率之间具有较好的线性关系;并且与游离鸡肝酯酶相比,固定化酶不同程度地降低了对农药检测的下限值。敌敌畏、马拉硫磷和西维因的检测下限值依次从游离酶检测时的0.001、4.34和2.52mg,L,降低到了用固定化酶检测时的0.00004、0.0004和0.78mg/L。固定化的鸡肝酯酶对敌百虫的检测下限改善不大。  相似文献   

3.
壳聚糖固定化α-葡萄糖苷酶的研究   总被引:21,自引:0,他引:21  
以粉末状壳聚糖为载体 ,采用吸附 交联的方法将α 葡萄糖苷酶固定化。在最适固定化条件下 ,室温吸附 6h ,然后与 3 5%的戊二醛在 4 5℃交联 6h ,可得到固定化酶的活力为1430 0U ,酶活力回收率为 59 6 %。通过实验发现 ,与游离酶相比 ,固定化酶的最适 pH向酸性方向移动 0 5pH单位 ,为 pH 4 5;最适作用温度达到 70℃ ,比游离α 葡萄糖苷酶提高 5℃ ;酸碱稳定性、热稳定性及贮存稳定性均有较大提高 ;在 6 0℃操作半衰期为 16 8h  相似文献   

4.
农药生物传感器所用酶的比较研究   总被引:14,自引:1,他引:13  
王仲海  徐斐 《食品科学》2003,24(1):21-23
在利用农药对酶的抑制反应来检测农药的方法中,选用的酶既可以是动物酯酶,也可以是植物酯酶。本文采用分光光度计法,对植物再生产 动物酯酶在不同pH值下的酶活,抑制程度等性质进行了实验研究。结果表明:动物酯酶中的苍蝇酶,蝇蛆酶与植物酯酶中的小麦酯酶相比,它们的活力和被农药抑制程度处于相近的;植物酯酶中小麦与玉米相比,玉米酯酶的活力远低于小麦酯酶的活力,不适于用来进行抑制反应检测农药。动物酯酶在pH值为7.5时活力最高,小麦酯酶在pH值6.5时最高。  相似文献   

5.
以自制壳聚糖为载体,戊二醛为交联剂将胰蛋白酶固定化。5%戊二醛在30℃下处理载体8h,加10ml酶液(0.3mg/ml,pH7.0)固定12h以上,活力回收率达67%-75%。固定化酶的表观米氏常数(酪蛋白)k'm=22.22mg/ml,而游离酶k'm=4.17mg/ml;固定化酶最适温度为80℃,比游离酶提高了30℃;固定化最适pH值为7.5,而游离酶为8.0;固定化酶的贮存稳定性很好,二个多月重复使用,酶活力未见明显下降。  相似文献   

6.
以介孔分子筛SBA-15为载体,戊二醛为交联剂,对糖化酶进行了固定化.考察固定化温度、时间、给酶量、pH值以及戊二醛浓度等因素对固定化效果的影响,并对固定化酶的酶学性质进行了研究.结果表明,糖化酶最佳固定化条件是:酶与载体比例50mg/g、固定化温度25℃、固定化时间4h、pH 5.1、戊二醛体积分数7.5%,此条件下固定化酶活力回收率为56%.固定化酶的最适作用温度为70℃,比游离酶高10℃.最适作用pH 4.1,比游离酶降低0.5个单位.米氏常数Km由原来的0.032mol/L降为0.022mol/L.用超声波对固定化酶进行处理,其酶活力提高了18%.所得最佳超声参数是:超声功率100W,温度70℃,时间5min.  相似文献   

7.
游离果胶酶和固定化果胶酶的酶学性质   总被引:12,自引:3,他引:9  
研究游离果胶酶和固定化果胶酶的酶学性质,结果表明,游离酶的最适温度为55℃,最适pH为4.0,明胶固定化酶的最适温度为60℃,最适pH为3.5,固定化酶的稳定性比游离酶更好,底物与固定化酶的亲和力增强。  相似文献   

8.
固定化脂肪酶性能研究及在洗毛中的应用   总被引:1,自引:0,他引:1  
利用硅藻土吸附法对解酯假丝酵母发酵产生的脂肪酶进行了固定化,研究了固定化酶和游离酶的酶学性质,以及用固定化脂肪酶对羊毛进行生物酶法洗毛。结果表明:固定化酶比游离酶的最适作用温度提高了5℃,最适作用pH值向碱性方向移动了0.5个单位,热稳定性和pH值稳定性有了大幅度提高。在固定化酶的最适作用pH值下,得到最佳的洗毛条件为:温度45℃、浴比1∶35、时间20 h。  相似文献   

9.
厉成宣  范雪荣  王强  王钦清 《印染》2007,33(21):1-4
以高碘酸钠氧化棉织物为载体固定过氧化氢酶,研究其固定化的主要条件,考察了固定化酶的性质。试验结果表明,过氧化氢酶固定在氧化棉织物上时,棉织物的最佳氧化条件为:NalO4浓度0.20mol/L,氧化时间8h,氧化浴pH值6.0,氧化温度40℃;过氧化氢酶固定化的条件为:过氧化氢酶用量0.20mL/(g棉织物),固定化时间24h。固定化酶的最适温度比游离酶提高了约10℃,使用温度范围变宽;固定化酶的最适pH值为7.0与游离酶相同,在酸性范围内稳定性较游离酶差,但在弱碱性范围内稳定性比游离酶好。  相似文献   

10.
以海藻酸钠为载体固定化亚油酸异构酶。研究了海藻酸钠浓度、酶用量、CaC12浓度、固定化时间对固定化过程的影响。结果表明,最佳固定化工艺是:以4%的海藻酸钠为载体、应用海藻酸钠溶液用量与酶液量的体积比3:1、3%的CaC12固定化5h。固定化酶的最适pH值为7.0,与游离酶相比,提高了0.5个pH单位;固定化酶和游离酶最适温度分别为35℃和30℃;固定化酶比游离酶具有更好的温度和pH值适应性。  相似文献   

11.
Acetic acid esterase (AAE) (E.C 3.1.1.6) and ferulic acid esterase (FAE) (E.C 3.1.1.73) cleaves the acetyl groups substituted at O-2/O-3 of the xylan backbone and feruloyl groups substituted at 5′–OH group of arabinosyl residues, respectively of arabinoxylans. These enzymes modulate the functional properties of cereal arabinoxylans such as viscosity, foam stabilization and gelling. In the present study, water-soluble non-starch polysaccharides (WSPs) from ragi, wheat flours were isolated, and their functional characteristics were studied in the presence of purified esterases. Relative viscosities of the enzyme treated WSPs were marginally less than the untreated ones. Untreated WSPs from wheat and ragi were found to stabilize the thermal disruption of protein foams compared to the esterase treated ones. AAE treated WSPs of wheat and ragi showed increased gelation while FAE treated ones showed slight decrease in comparison with their respective controls. Xanthan gum (XG), which was deacetylated by purified AAE, showed improved gelation (ratio of relative viscosities for 0, 1 and 2 h of control and enzyme treated blend is 1:1.16, 1:1.35 and 1:1.20, respectively) when blended with locust bean gum (LBG).  相似文献   

12.
BACKGROUND: In enzyme inhibition‐based biosensors for the detection of organophosphate and carbamate pesticides, the biological element is the immobilised esterase which is inhibited selectively by the pesticides. The free chicken liver esterase, which possesses comparable inhibition response to the pesticides as AChE, has been reported. However, the responses to the pesticides are different between the free and immobilised enzyme due to the diffusion limitation. Therefore, in this study four typical pesticides were selected to compare the ability of free and (ion exchange) immobilised chicken enzyme for pesticide detection and reasons for the difference were investigated. RESULTS: For dichlorvos and malathion at a concentration of 0.1 mg L?1, the inhibition of the immobilised enzyme was 26.98% and 48.72%, respectively, higher than that for the free enzyme, while the percentage inhibition of free and immobilised enzyme differed very little for trichlorfon at 0.1 mg L?1. In the meantime, carbaryl at a concentration of 2.5 mg L?1 showed a 17.72% inhibition for immobilised enzyme which was 13.64% higher than that for the free enzyme. The Michaelis constant of immobilised enzyme was lower than that of the free one and suitable pH values for the free and immobilised enzyme were 7.5 and 8.0, respectively. CONCLUSIONS: The sensitivity of chicken liver esterase to the pesticide inhibition could be improved by immobilisation. Smaller Km and a lower pH for the micro‐environment of immobilised enzyme should result in higher percentage inhibition compared with that of the free enzyme. Copyright © 2008 Society of Chemical Industry  相似文献   

13.
研究从小麦面粉提取小麦酯酶提取条件及其粗酶液对4种有机磷农药最低检测限和灵敏度。运用单因素实验和正交实验对小麦酯酶提取条件进行优化,确定适宜提取条件,提取液为0.15 mol/L NaCl溶液、料液比1∶4、40℃振荡提取60 min,提取粗酶液酶活为1.675 U/mL;并确定粗酶液对敌敌畏、敌百虫、乐果和毒死蜱等4种有机磷农药最低检测限分别为0.05 mg/kg、0.04 mg/kg、0.05 mg/kg和0.07 mg/kg,均低于国家规定农药最大残留量,且粗酶液对敌敌畏灵敏度最佳。  相似文献   

14.
小麦酯酶固定化条件的研究   总被引:1,自引:0,他引:1  
考察了小麦酯酶固定化条件的影响因素,并对固定化酶的性质进行了研究。结果表明,其固定化最佳条件为:固定化时间12h、海澡酸钠浓度为3%、戊二醛浓度6%、氯化钙浓度为0.5mol/L。  相似文献   

15.
用于有机磷农药残留快速检测的固定化小麦酯酶研究   总被引:33,自引:5,他引:28  
许学勤  徐斐  华泽钊 《食品科学》2003,24(5):122-126
以大孔径强碱性阴离子交换树脂作为固定化载体,采用离子结合法,对植物粗酶液进行固定化。在室温及酶液对载体比例为4(ml):1(g)的条件下,对酶固定化的环境pH值、缓冲液浓度及固定化特性进行了研究。得到的固定化酶对l0^-7mol/L水平下敌敌畏的抑制仍有明显的响应,这一效果明显优于游离酶的抑制响应。  相似文献   

16.
M. Kanauchi    S. Watanabe    T. Tsukada    K. Atta    T. Kakuta    T. Koizumi 《Journal of food science》2008,73(6):C458-C463
ABSTRACT:  For food industry production processes and other uses, a mold that produces high levels of feruloyl esterase was obtained from laboratory mold collections and other sources. It was Aspergillus awamori G-2 that produces high levels of feruloyl esterase. The feruloyl esterase was purified using ion-exchange chromatography, size-exclusion chromatography, and HPLC chromatography. The enzyme was identified as a monomer protein using size-exclusion chromatography. Its optimum temperature and pH were, respectively, 40 °C and pH 5. Its activity was stable at pH 3 to 5. The enzyme was combined with xylan and starch, but it was absorbed by cellulose. The km of the feruloyl esterase was 0.0019% (0.01 mM). The enzyme showed stable activity at pH 3 and 50 °C, making this enzyme useful for food production.  相似文献   

17.
Starch hydrolysing enzyme α-amylase (EC 3.2.1.1) was immobilized by physical adsorption and covalent binding onto chemically synthesised polymer, polyanilines (PANIs) in two different forms, emeraldine salt and emeraldine base powder. The immobilization efficiency was affected by the pH of the immobilization medium, contact time and amount of enzyme. The kinetic parameters, reusability and storage stability of the enzyme were studied under free and immobilized condition at optimum pH and temperature. The immobilized enzyme showed enhanced storage stability over a period of 6 months, while free enzyme in solution lost all of its activity within a period of 8 days. Reusability of the enzyme was improved by immobilization. The Km values for starch hydrolysis were found to be high for the immobilized enzymes.  相似文献   

18.
聚乙烯醇(PVA)具备优良的生物相容性和大量可以用于修饰的羟基。文中通过戊二醛交联得到水不溶性PVA小珠,对PVA小珠的表面进行环氧改性,并采用共价交联法固定化α-淀粉酶。对固定化与自由α-淀粉酶性质进行对比:固定化酶的最适催化温度(70℃)比自由酶(65℃)高,最适催化pH(6)与自由酶相同,热稳定性优于自由酶,对酸碱的敏感性也降低;重复使用8次仍保持60%酶活力。  相似文献   

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