蒙脱石固定化α-淀粉酶和糖化酶的研究

以蒙脱石为载体,利用吸附法分别固定α-淀粉酶、糖化酶以及共固定化α-淀粉酶和糖化酶。α-淀粉酶和糖化酶最佳固定化温度分别是20℃和30℃,最佳固定化pH是6.5和4.5。共固定化最佳条件为淀粉酶(U):糖化酶(U):蒙脱石(g)为15:7.5:0.2,pH为5.5;温度为20℃。固定化α-淀粉酶、固定化糖化酶和共固定化酶的最适pH分别为6.0、4.5和5.5,最适反应温度分别是60、60℃和55℃。蒙脱石固定化α-淀粉酶、固定化糖化酶和共固定化酶的稳定性均较好,尤其是共固定化酶表现突出。     

马来松香改性丙烯酸树脂的合成及其性能研究

本文以马来松香为原料,通过其与丙烯醇的酯化反应合成马来松香丙烯醇酯,然后用马来松香丙烯醇酯与丙烯酸酯类单体通过半连续乳液聚合的方法制成了新型水性纸塑复膜胶。使用红外光谱分析了酯化产物马来松香丙烯醇酯的结构,并对其酸值进行了测量。同时用差示扫描量热法及红外光谱对改性的丙烯酸树脂进行了分析并对其黏结性能和稳定性能进行了测量评价。此外,实验还得出了酯化反应的最佳反应温度为110℃;对于乳液聚合,最佳的反应温度为85℃,丙烯酸的量为5.9%,且随着马来松香丙烯醇酯质量的增加,乳液的固含量降低,但剥离强度增强。测试结果表明,马来松香改性的丙烯酸树脂乳液表现出了较好的油墨吸附效果,并具有黏结性强、稳定性好、成本低等特点。     

核-壳型松香基磁性聚合物固定化脂肪酶的制备及性能

以甲基丙烯酸和丙烯酸为单体,马来松香乙二醇丙烯酸酯为交联剂,采用共沉淀法及悬浮聚合法制备出具有磁性的核-壳结构的球状聚合物（Fe3O4@RAM）。以之为载体,用化学交联法固定脂肪酶。在50%的戊二醛用量为1.5%,交联时间4 h,酶与载体的质量比为2∶1的条件下,制得的固定化酶的酶活回收率达到86.17%。固定化酶的热稳定性、储存稳定性及操作稳定性均有所提高。重复使用7批次,酶活仍高于73.52%。     

阳离子无皂苯丙聚合物分散松香胶与AKD复配施胶剂的制备及性能

将松香、阳离子单体甲基丙烯酰氧乙基三甲基氯化铵(DMC),非离子单体丙烯酰胺(AM)、苯乙烯(St)及丙烯酸丁酯(BA),交联单体N-羟甲基丙烯酰胺(NMA)一次性投入,采用优化的工艺制备阳离子无皂苯丙聚合物,用该聚合物乳化分散逆转松香制得阳离子分散松香胶。在65℃搅拌下,向阳离子分散松香胶中加入18Wt%AKD(占松香)对其改性,得分散松香、AKD施胶剂。实验研究表明该乳胶具有优异的分散性和稳定性。施胶实验结果显示:在浆料pH值为6.5、助留剂CPAM为0.25%、分散松香胶与AKD用量为1.3%(占磨木浆)施胶时,施胶度达86s;填料GCC为15%～20%时,仍具有良好的施胶效果,可用于中性抄纸。     

微溶剂体系酶法合成松香酸淀粉酯

以松香和木薯淀粉为原料,叔戊醇为溶剂,研究了微溶剂体系下采用酶催化酯化法合成松香酸淀粉酯。通过单因素实验考察了松香与淀粉质量比、反应时间、反应温度、固定化脂肪酶用量对松香酸淀粉酯取代度的影响,确定最适反应条件为:松香与淀粉的质量比为4∶1,反应温度为55℃,反应时间为10 h,固定化脂肪酶用量为4%(以淀粉质量计)。通过红外光谱分析产物的结构发现,产物在1 725 cm-1处出现了酯羰基C=O的伸缩振动吸收峰,表明松香与淀粉发生了酯化反应合成了松香酸淀粉酯;通过X射线衍射分析和扫描电镜分析产物的结构发现,酯化反应没有破坏淀粉原有的晶体型貌和结构。对产物的亲油性能进行研究,结果表明,与原淀粉相比酯化产物在正辛烷中对橄榄油的吸附能力增加了166.67%。微溶剂体系的反应大大降低了成本,提高了产物的量。     

新型松香石蜡阳离子中性施胶剂的制备及应用

以N-甲基吡咯烷酮(NMP)为助溶剂,苯乙烯(St)、丙烯酸十八酯(ODA)、甲基丙烯酰氧乙基三甲基氯化铵(DMC)、丙烯酰胺(AM)为单体,通过无皂乳液共聚反应合成了阳离子高分子乳化剂(CPE),并制备了阳离子松香石蜡乳液(CRPE).研究TCPF合成中St、ODA、DMC含量对CRPE稳定性能的影响;CRPE中松香、石蜡、CPE质量比对CRPE稳定性能以及施胶性能的影响;纸浆pH、CRPE用量及非离子聚丙烯酰胺用量对纸张施胶效果的影响.结果表明:W(St)=33%、w(ODA)=15%、w(DMC)=17%、m(松香):m(石蜡):m(CPE)=2:1:3时CRPE稳定性能较好,适宜的施胶条件为:采用逆向施胶工艺纸浆pH值为6,CRPE用量为1%,PAM用量为0.8%.     

磁性聚乙烯醇微球固定化β-淀粉酶的研究

磁性聚乙烯醇微球为载体,采用戊二醛交联法固定化β-淀粉酶,并对固定化酶的理化性质等进行了研究。结果表明,磁性固定化β-淀粉酶的总活力、蛋白载量、比活、活性回收率分别为7207.62 U/g,157.21 mg/g,45.85 U/mg和52.38%;固定化β-淀粉酶的反应最适温度和最适pH分别为70℃和5.O;Fe~(2+)和Cu~(2+)对β-淀粉酶有较强的抑制作用,而Zn~(2+)对其有很强的激活作用,Mg~(2+)则不影响β-淀粉酶的活性;β-淀粉酶被固定化后其热稳定性(在水介质中)、操作稳定性、pH稳定性均比自由酶的明显提高。固定化β-淀粉酶在4℃,pH 4.5的缓冲液中保存31 d,其活力仍保持最初活力的98.3%,这比其自由酶的提高26%。     

松香基网状高分子交联包埋固定化淀粉酶

利用松香基功能高分子网状交联包埋固定化淀粉酶,考察了酶固定化的最佳条件及固定化酶性能。结果表明,在50℃,Ca2+浓度为50 mL、1 mol/L,反应3 h的条件下制备的固定化酶效果最佳。固定化酶最适反应温度为60℃,比游离酶提高10℃,最适pH为5.00,重复使用6次,酶活性还保持64%。采用红外、SEM技术对固定化酶的结构及外观进行了分析,进一步证实合成了固定化淀粉酶。     

马来松香乙二醇丙烯酸酯-丙烯酰胺共聚物对葛根素的吸附性能

以马来松香乙二醇丙烯酸酯(EGMRA)和丙稀酰胺(AM)为聚合单体,采用悬浮聚合法合成马来松香乙二醇丙烯酸酯-丙稀酰胺二元共聚物(松香基聚合物)。采用静态法研究该聚合物对葛根素吸附过程的热力学和动力学特性,对吸附过程进行控制机理判断。结果表明:该聚合物对葛根素具有良好的吸附能力,最佳吸附条件为:以体积分数为40%乙醇为溶剂配制葛根素溶液,质量浓度为6.0mg/mL,聚合物为20～40目,吸附温度25～50℃,振荡频率80r/min,平衡吸附时间为2h。饱和吸附量Qe为23.01mg/g。拟二级吸附动力学模型可较好的描述吸附过程,膜扩散和粒扩散为此吸附体系控制步骤,通过菲克定律计算出膜扩散系数D为5.22×10-8cm2/s,粒扩散系数D为3.20×10-8cm2/s。     

改性松香的探讨

本文采用马来酸和富马酸作为改性剂，对影响松香性能的因素、改性机理以及强化松香的主要组成进行了初步的研究。研究结果表明：（1）强化松香的酸值、皂化值的软化点都随着加成量的增加而提高，基本上呈线性关系；（2）强化松香的马来酸或富马酸的加成量应控制在3%-5%范围内为宜；（3）富马酸的主要成分为松香酸和富马海松酸，马来松香的主要成分除了松香酸和马来海松酸以外，还有马来海松酸酐和马来海松酸酯；（4）在加成量相同的情况下，富马松香与马来松香相比具有较低的软化点和皂化值，却有较高的酸值，有利于改善强化松香胶和分散松香的质量。     

Polyacrylamide–gelatine carrier system used for invertase immobilization

Invertase was immobilized into polyacrylamide–gelatin carrier system by chemical cross-linking with chromium (III) acetate, chromium (III) sulphate, and potassium chromium (III) sulphate. The optimum conditions, namely substrate concentration, temperature, and pH were determined. The effect of polyacrylamide–gelatin ratio and cross-linker concentration on immobilized enzyme activity were analysed. Maximum immobilized enzyme activities were obtained with chromium (III) acetate (0.01 mol dm⁻³), chromium (III) sulphate (0.004 mol dm⁻³) and potassium chromium (III) sulphate (0.001 mol dm⁻³) for 0.177 (w/w) polyacrylamide–gelatin carrier ratio as 79%, 72% and 79%, respectively. The K_m values were 86 and 166 mM for free and immobilized enzyme, respectively. All immobilized samples were used 20 times over a period of 2 months without a considerable loss of activity.     

Preparation and characterization of immobilized beta-lactamase for destruction of penicillin in milk

beta-Lactamase I (Bacillus cereus) was covalently bound to cyanogen bromide-activated, crosslinked agarose. An initial 5.00 mg of soluble beta-lactamase were used in the immobilization reaction for each preparation, and average coupling yield was 80.5%. Of the enzyme immobilized on the matrix, an average 53.4% remained active. To minimize diffusional effects on immobilized enzyme activity, reaction mixtures were rotated at 250 rpm throughout the study. The shape of the pH activity curve of the immobilized enzyme was identical to that of the soluble enzyme; both exhibited optimum pH around 7.0. In general, only 2-fold differences in Michaelis constant and maximum volume were observed between native and immobilized enzyme when penicillin G was used as the substrate. However, the Michaelis constant of the immobilized enzyme increased up to 22-fold that of the native enzyme when cephaloridine was used as the substrate. The immobilized enzyme exhibited enhanced stability in the acidic pH region in contrast to the native enzyme, which had superior stability in the alkaline pH region. The heat stability of the immobilized enzyme was about twice that of native enzyme after heat treatment at 60 degrees C for 30 min. Approximately a 10% increase of storage stability on immobilization of beta-lactamase was observed when stored at room temperature (23 +/- 1 degree C) for up to 6 d in the absence of antimicrobial agents. Little loss of activity (less than 2%) was noted after repeated use of the immobilized enzyme up to seven times each in 10.0 ml of skim milk containing .5 U/ml penicillin G.(ABSTRACT TRUNCATED AT 250 WORDS)     

Use of Cu(II) and Fe(III) N-benzoyl-N-phenylhydroxylamine coprecipitants for preconcentration of some trace metal ions in food samples

In this study, new coprecipitation methods were developed using a combination of N-benzoyl-N-phenylhydroxylamine (BPHA) as a chelating reagent and copper(II) and iron(III) as coprecipitate carriers. The determinations of Fe(III), Cr(III) and Cr(VI) with Cu(II)–BPHA coprecipitant and of Cu(II), Pb(II), Cr(III) and Cr(VI) with Fe(III)–BPHA coprecipitant were made by flame atomic absorption spectrometry. The surface morphology of coprecipitants was examined by scanning electron microscopy. The coprecipitation conditions for each method such as the effect of pH, the amounts of carrier element and BPHA, sample volume and matrix effects were examined. The optimum pH for each method was found to be 6. The detection limits of the methods changed in the range of 0.23–3.2 μg L⁻¹ with an enrichment factor of 100. The RSD % was ?4.2. The accuracy of the methods was confirmed by analysing the certified reference material. The developed methods were applied for the determination of analytes in food samples.     

多胺柔性链改性壳聚糖微球固定化木瓜蛋白酶

用反相悬浮交联法制备了单分散壳聚糖微球树脂,以其作为固定化载体基体,经氨基保护、C6羟基环氧化后接枝亲水性多乙烯多胺,制备了粒径为220～300μm、具有较高机械强度的多胺柔性链改性壳聚糖载体。采用该载体对木瓜蛋白酶在pH8.0缓冲液中室温下固定25h,固定化酶表观活力最高可达313U.g-1,活力回收率最高达61.5%,是采用未经多胺分子修饰的壳聚糖微球固定化的2.3倍。该柔性固定化酶的最适温度为65℃,最适pH为8.0,连续使用6～7次后仍保持原来活力的一半。     

高碘酸钠氧化法固定化脂肪酶的研究

研究了以醋酸纤维素/聚丙烯复合膜为载体的高碘酸钠氧化法固定化脂肪酶的固定化条件,采用响应面分析法对固定化条件进一步优化,并对固定化酶膜的酶学性质进行了讨论。结果表明,以固定化酶活力为指标,当高碘酸钠浓度为0.15 mol/L,活化为60 min时,浓度为0.013 g/mL的酶液与pH 8.0的磷酸盐缓冲溶液于戊二醛质量分数0.24%,温度4℃下,进行交联反应,反应3.1 h后,获得的固定化酶活最高,为0.52 U/cm2。固定化酶膜的酶学性质为:固定化酶最适温度35℃,最适pH为9.0。     

The efficacy of sand-immobilized organoclays as filtration bed materials for bacteria

Previous research has shown that montmorillonite clays exchanged with cationic surfactants including cetylpyridinium (CP), hexadecyltrimethylammonium (HDTMA), and cetyldimethylethylammonium (CDEA) were effective in reducing Salmonella enteritidis colony counts in bulk antibacterial assays. In order to increase the porosity (and hydraulic conductivity) of these materials for use in filtration beds, organoclays were tightly adhered and immobilized onto the surface of sand. Bulk antibacterial assays performed with 10 mg of the sand-immobilized organoclay (S/IOC) showed that the composite materials retained their antibacterial activity after processing. Reductions in plate colony counts ranged from 16.5% for sand-immobilized CP-exchanged sodium montmorillonite to 83.9% for immobilized CDEA-exchanged low pH montmorillonite. The sand/adhesive matrix and sand-immobilized activated charcoal failed to produce any significant decreases. Pilot studies with columns containing 1.0 g of S/IOC showed that maximal filtration efficiency was obtained at a filtration rate of 1.0 ml/min. Initial column studies with Salmonella suspensions at a concentration of 3.0×10⁸ cfu/ml, produced reductions in colony plate counts varying from 28.5% for immobilized CP-exchanged calcium montmorillonite to 59.5% for immobilized CDEA-exchanged low pH montmorillonite. The sand/adhesive matrix and immobilized activated charcoal yielded much lower reductions (7.6% and 10.4%, respectively). Studies with Escherichia coli suspensions (3.0×10⁷ cfu/ml) indicated reductions varying from 59.3% for immobilized CP-exchanged calcium montmorillonite to 99.9% for immobilized CDEA-exchanged low pH montmorillonite. These initial results suggest that S/IOC can be effective in reducing microbial numbers in wastewater following some modifications.     

MCM-41固定化柚苷酶脱苦葡萄柚汁

以介孔分子筛MCM-41为载体,戊二醛为交联剂,采用吸附-交联法进行了柚苷酶的固定化。研究了酶液浓度、戊二醛浓度、吸附交联时间和固定化pH对固定化效果的影响,对影响固定化效果的因素进行了分析。确定最佳的固定化条件为:酶液浓度为0.4mg/mL,戊二醛浓度2.0%,吸附交联时间为6h,固定化pH为4.0(醋酸缓冲液)。采用海藻酸钠和聚乙烯醇对制备的固定化酶进行二次包埋处理,并应用于葡萄柚汁的脱苦。结果显示,游离酶和MCM-41固定化酶对果汁的脱苦率分别为96.65%和92.90%,海藻酸钠和聚乙烯醇二次固定化的柚苷酶脱苦率分别为72.64%和70.90%。脱苦后的果汁营养成分与理化指标均有一定程度降低。为柚苷酶的固定化提供了一种新型的载体材料,为固定化柚苷酶在果汁脱苦中的工业化应用提供了理论基础。     

Lignin-degrading enzyme production by Bjerkandera adusta immobilized on polyurethane foam

Production of the lignin-degrading enzymes lignin peroxidase (Lip), manganese peroxidase (MnP), and laccase (Lac) by the white-rot fungus Bjerkandera adusta was investigated experimentally using polyurethane foam (PUF) as a carrier of immobilized fungal mycelia. An immobilized cell culture with a low-nitrogen medium yielded significantly greater LiP, MnP, and Lac activities in comparison with those obtained in a liquid culture. The maximum activities of the three enzymes were 450, 370, and 100 U/ml, respectively, under the following incubation condition: glucose concentration, 20 g/l; temperature, 30 degrees C; pH 4.5. The activities of MnP and Lac were significantly higher than those reported using other incubation methods. Lignin was degraded to the extent of 40% and its decolorization ratio was about 70% at an incubation time of 40 h using lignin-degrading enzymes from B. adusta. Six different isozymes of MnP were synthesized by B. adusta, two of which exhibited high MnP activity. Our preliminary finding that extracellular enzymes from B. adusta are capable of degrading and decoloring lignin makes these enzymes attractive for further research aimed at their large-scale application in lignin depolymerization, pulp biobleaching, and the degradation of toxic pollutants.     

采用双层静电自组装技术制备nPAM-木瓜蛋白酶-CNC催化剂

本研究利用载体材料纤维素纳米晶(CNC)、木瓜蛋白酶(papain,PA)以及非离子型聚丙烯酰胺(non-ionic polyacrylamide,n PAM)的表面电荷特性,制备了新型的固定化木瓜蛋白酶,利用Zeta电位分析,探寻固定化过程中的静电作用机制;并通过傅立叶变换红外光谱(FT-IR)分析固定化PA的组成成分和各物质的相互作用。通过对固定化过程中的各因素进行研究,得到了制备该固定化酶的最优条件,分别为p H 5.0,CNC和PA质量比为36:1(CNC/PA),n PAM(5%质量分数)的添加量为0.3 m L,酶层自组装时间30 min;在此条件下酶活回收率达85.8%。随后,对游离酶和固定化酶的动力学参数研究显示固定化酶的Vmax/Km值(1.40 min-1)明显高于游离酶(0.80 min-1),表明所制备的固定化PA具有更高的催化效率、更广的最适p H范围和温度范围以及操作稳定性,在重复使用5批次之后,相对酶活仍在96.5%以上。可见双层自组装技术是一种进行固定化酶的新途径。