新型双醛淀粉-SiO_2杂化材料固载纤维素酶及其酶学性能研究

利用溶胶-凝胶原理制备氨基化二氧化硅(Si O2-NH2),表面接枝双醛淀粉制备新型固载酶载体(Si O)2-DAS)。红外光谱(FT-IR)、固体核磁共振波谱(CP/MAS 13C-NMR)、X-射线衍射(XRD)和扫描电镜(SEM)表征Si O2-DAS分子结构。Si O2-DAS固载纤维素酶制备新型固定化纤维素酶,测试固定化纤维素酶的酶学性能,并与经典交联固定化酶(Si O)2-GA)和游离酶的酶学性能进行比较分析。结果表明,成功合成新型Si O2-DAS材料,所得Si O2-DAS固定化纤维素酶与Si O2-GA交联固载纤维素酶和游离酶相比,在较宽的温度和p H范围内保持酶活性。Si O2-DAS和Si O)2-GA两种固定化纤维素酶的米氏常数分别为1.6766 g×L-1和2.3060 g×L-1,游离纤维素酶的米氏常数为1.1856 g×L-1,试验表明Si O)2-DAS对底物的亲和能力更强,并具有良好的重复使用性和贮存稳定性。有关研究可为制备性能优良的杂化基质材料固载酶提供借鉴。

脲酶颗粒化制剂的制备及酶学性能研究

以壳聚糖为载体、戊二醛为交联剂,采用包埋-交联法制备颗粒化固定脲酶,单因素实验考察固定化条件对固定化脲酶活性的影响。研究了制备的固定化脲酶的酸碱耐受性、温度适应性、酶催化反应性及贮存稳定性,建立了酶活方程并与游离酶的酶学活性进行了比较。结果表明,制备固定化脲酶的优选条件为:脲酶与壳聚糖质量配比为1∶25,凝结液浓度为20%NaOH和30%CH3OH溶液,交联剂质量浓度为0.5%,交联时间为10 min。优选条件下制备的固定化脲酶的酶比活为5.0 U·g-1载体,包覆率为90.1%,最适pH值为6.6,最适温度为45℃,米氏常数为0.009 2 mol·L-1,重复使用性和贮存稳定性较游离酶均有很大改善。

纤维素基质固载酶材料制备及固定化漆酶性能

以微晶纤维素(MCC)为原料,采用新型水热氧化合成方法,制备纤维素基质固定化漆酶载体材料———双醛纤维素(DAC)。红外光谱(IR)、固体核磁共振(CP/MAS13C NMR)、X-射线衍射(XRD)和扫描电镜(SEM)表征产物结构。测试制备的纤维素基质固载漆酶的酶学性能,并与交联壳聚糖、双醛淀粉固载漆酶的酶学性能进行比较分析,构建酶学性能理论方程。结果表明:新型水热氧化反应成功制备了高醛基含量的氧化纤维素,所得氧化纤维素载体材料固定化漆酶与交联壳聚糖和双醛淀粉固定化漆酶相比,稳定性好,重复使用率高,可在较宽温度和pH范围内保持酶活性,建立的理论方程较好表征了固载酶酶学性能。

新型方法制备固定化脲酶基质材料及固定化脲酶的性能研究

以微晶纤维素（Microcrystalline cellulose,MCC）为原料,采用新型水热氧化方法,制备纤维素基质固定化脲酶载体材料-双醛纤维素（Dialdehyde cellulose,DAC）。采用红外光谱（IR）、固体核磁共振（CP/MAS 13C NMR）、X-射线衍射（XRD）和扫描电镜（SEM）表征产物结构。测试制备的纤维素基质固载脲酶的酶学性能,并与交联壳聚糖、双醛淀粉固载脲酶的酶学性能进行比较分析,构建酶学性能理论方程。结果表明：采用新型水热氧化反应可成功制备高醛基含量的氧化纤维素,与交联壳聚糖和双醛淀粉固定化脲酶相比,所得氧化纤维素载体材料固定化脲酶的米氏常数小（0.0108mol·L-1）,对底物亲和能力强,重复使用率高,在pH=5.0~9.0能保持酶活性,建立的理论方程较好地表征了固载酶酶学性能。

纤维素基固载酶材料的制备及乙酰胆碱酯酶的固定化性能

采用新型水热氧化合成方法制备了纤维素基质固定化乙酰胆碱酯酶载体材料——双醛纤维素(DAC)。通过红外光谱(IR)、核磁共振(NMR)、X射线衍射(XRD)和扫描电镜(SEM)对产物进行了表征。测试了DAC固载乙酰胆碱酯酶(AChE)的酶学性能,并与交联壳聚糖(CCTS)、双醛淀粉(DAS)固载AChE的酶学性能进行比较分析,构建了酶学性能理论方程。结果表明,新型水热氧化反应制得了高醛基含量的DAC;DAC固定化AChE与CCTS和DAS固定化AChE相比,稳定性好(10次重复利用率),可在25℃~55℃和pH 4.0~8.0范围保持酶活性;建立的理论方程较好地表征了固载酶的酶学性能。

表面复合修饰纳米超顺磁性材料固定化α-淀粉酶性能研究

以复合修饰的纳米超顺磁性Fe3O4颗粒聚集体为载体固定化α-淀粉酶,比较分析固定化α-淀粉酶及游离α-淀粉酶的酶学性能。研究固定化及游离α-淀粉酶的最适温度、最适p H、操作稳定性及基本动力学等。结果表明,固定化α-淀粉酶最适p H为7,最适温度为60℃。固定化α-淀粉酶与游离α-淀粉酶相比,具有更好的温度和酸碱的耐受性。固定化α-淀粉酶重复催化反应10次,相对酶活力仍剩余72.09%,重复操作的半衰期为18.97次,具有良好的操作稳定性。固定化α-淀粉酶的米氏常数Km值为45.31 mg/m L,亲和性弱于游离α-淀粉酶。

Is kinase activity essential for biological functions of BRI1？

Brassinosteroids （BRs） are a major group of plant hormones that regulate plant growth and development. BRI1, a protein localized to the plasma membrane, functions as a BR receptor and it has been proposed that its kinase activity has an essential role in BR-regulated plant growth and development. Here we report the isolation and molecular characterization of a new allele of bril, bril-301, which shows moderate morphological phenotypes and a reduced response to BRs under normal growth conditions. Sequence analysis identified a two-base alteration from GG to AT, resulting in a conversion of 989G to 9891 in the BRI1 kinase domain. An in vitro assay of kinase activity showed that bril-301 has no detectable autophosphorylation activity or phosphorylation activity towards the BRI1 substrates TTL and BAK1. Furthermore, our results suggest that bril-301, even with extremely impaired kinase activity, still retains partial function in regulating plant growth and development, which raises the question of whether BRI1 kinase activity is essential for BR-mediated growth and development in higher plants.

Studies on Partial Molar Volumes of Some Amino Acids and Their Groups in Aqueous Solutions from 293.15K to 333.15K

Densities of aqueous solutions of eight amino acids, glycine, L-alanine, L-valine, L-isoleucine, L-serine, L-threonine, L-arginine and L-phenylalanine, are measured as a function of amino acid concentration from 293.15K to 333.15K. These data are used to calculate the apparent molar volume Vφ and infinite dilution apparent molar volume Vφo (partial molar volume). Data of five amino acids are used to correlate partial molar volume Vφo usinggroup contribution method to estimate the contributions of the zwitterionic end groups (NH3+,COO-) and CH2 group, OH group, CNHNHNH2 group and C6H5(phenyl) group of amino acids. The results show that Vφo values for all kinds of groups of amino acids studied increase with increase of temperature except those for CH2 group, which are almost constant within the studied temperature range. Data of other amino acids, L-valine, L-isoleucine and L-threonine, are chosen for comparison with the predicted partial molar volume Vφo using the group additivity parameters obtained. The results confirm that this group additivity method has excellent predictive utility.

Comparisons between Flotation Deinking Abilities of Newsprint Paper by Using Enzyme and Chemicals

The aim of this research is to study the floatation deinking abilities of black mold enzyme and chemicals in newsprint paper application. In this experiment, the properties of deinked pulp from three different additives--chemicals, black mold enzyme, and chemicals together with black mold enzyme, are studied. The first part of the experiment was to find the optimal amount of chemicals and the optimal pH through the use of sodium hydroxide and surfactant. As a result, 0.2% of sodium hydroxide and 0.4% of surfactant on oven dried weight at pH 9 was found to be the optimal condition for the deinked pulp to yield the lowest ERIC （effective residual concentration） and the highest brightness. The second part of the experiment was to find the optimal amount of black mold enzyme used in the deinking process. As a result, the optimal condition for deinked pulp to retain the lowest ERIC and the highest brightness was 100 ppm of black mold enzyme and 10 minutes of enzyme reaction time. The third part of experiment was to study the de-inking ability of black mold enzyme and chemicals. Consequently, with 30 min of chemicals reaction time and 60 min of black mold reaction time, the deinked pulp retained low ERIC but higher brightness.

Biochemical Mechanisms of Therapeutic and Prophylactic Effects of Bioflavonoids

In the present study to investigate the biochemical mechanisms of therapeutic and prophylactic action of bioflavonoids, carried out a comparative evaluation of antioxidant and antiproteinase properties of certain bioflavonoids standards in vitro. Therapeutic and prophylactic efficacy of individual bioflavonoids as well as herbal medicines with bioflavonoids, was examined at an experimental pathology （toxic hepatitis, dental caries, periodontitis, stomatitis, dysbiosis, diabetes Types 1 and 2, gastric ulcer, osteopenia） in Wistar line rats. Condition of organs and tissues was assessed by biochemical markers of inflammation, antioxidant and antimicrobial defense systems of animals. Research has shown the ability ofbioflavonoids in varying degrees inhibit the formation of superoxide anion radicals and malondialdehyde, recover free radicals, bind ions of Fe2＋, inhibiting the activity of proteases, such as leukocyte elastase. Established partially competitive type of trypsin and elastase activity inhibition by bioflavonoids. Was revealed a positive effect of bioflavonoids in experimental pathology on animals. Therapeutic and prophylactic effects of bioflavonoids, in our opinion, are realized through a strong antioxidant and antiprotease properties of these compounds.

Supramolecular protein glue to boost enzyme activity

Proteins possess many biological functions.However, they can easily degrade or aggregate, thus losing their bioactivity. Therefore, it is very important to develop materials capable of interacting with proteins and forming nanostructures for protein storage and delivery. In this study,we serendipitously found a novel peptide-based supramolecular protein glue(Nap-GFFYK(γE)2-NH2, compound 1) that could co-assemble with proteins into nanofibers and hydrogels. We found that compound 1 rapidly folded into a β-sheet conformation upon contact with many proteins but not with polymers. Total internal reflection fluorescence microscopy(TIRFM) images clearly show the formation of co-assembled nanofibers by proteins and the peptide. The supramolecular protein glue could improve the dispersion of enzymes(lipase and lysozyme) and therefore enhance their catalytic activity,especially at high temperatures. More importantly, the supramolecular protein glue could co-assemble with two enzymes, glucose oxidase/horseradish peroxidase(GOx/HRP)and GOx/cytochrome c(cyt c), to form nanofibers that significantly enhanced the catalytic activity of tandem enzymatic reactions. We envisioned the great potential of our supramolecular protein glue for protein storage, delivery, and bioactivity manipulation.

Effect of Yizhitongxuan decoction on learning and memory ability,Gαq/11 expression and Na^+-K^+-ATP enzyme activity in rat models of Alzheimer's Disease

OBJECTIVE: To study the effects of Yizhitongxuan decoction on learning and memory abilities, Gαq/11expression and Na+-K+-ATPenzymeactivityin rat models of Alzheimer's disease(AD) caused by injecting Aβ25-35 into the hippocampus.METHODS: Ninety male Wistar rats(age ≥10 months)were selected and injected with Aβ25-35 into their hippocampi to establish model animals,which were randomly divided into six groups including a sham-operated group(blank group), a model group, a donepezil HCL group(Western Medicinegroup),and ahigh/general/dilute concentrations of Yizhitongxuan decoction groups(TCMⅠⅡⅢgroup).The Morris watermaze was used to examine the learning and memory abilities of rats in each group by place navigation and spatial probe tests.Then, the rats were sacrificed to collect the hippocampi for biochemical tests, using western blotting to detect the expression of Gαq/11 and an ultramicro Na+-K+-ATP enzyme kit to measure Na+-K+-ATP enzyme activity.RESULTS:Yizhitongxuan decoction improved model rats' learning and memory abilities, and increased the expression of Gαq/11 in the hippocampus and the level of Na+-K+-ATP enzyme activity in braintissue.CONCLUSION: Yizhitongxuan decoction could improve model rats' learning and memory abilities,and had a regulating effect on the expression of Gαq/11and Na+-K+-ATP enzyme activity.

In situ generated thrombin in the protein corona of zeolites： Relevance of the functional proteins to its biological impact

Adsorption of plasma proteins to nanomaterial surfaces has a great influence on their bio-functionality. However, there is limited understanding of the relationship between the functional proteins in the protein corona and the biological identity of the materials. Here we show that the in situ generated thrombin in the protein corona of a Ca-zeolite surface displays a calcium-dependent, unusually high （-3,000 NIH U/mg） procoagulant activity, which is even stable against antithrombin deactivation. Removing the encapsulated Ca^2＋ in the zeolites leads to deactivation by antithrombin. Our observations suggest that the thrombin activity can be regulated by the inorganic surface and cations. Most importantly, our discovery indicates the link between the biomolecules in the protein corona and the procoagulant activity of the materials, providing a new molecular basis for the procoagulant mechanism for zeolite hemostatics.