聚乙烯醇、聚乙烯胺与淀粉酶相互作用荧光光谱

采用荧光光谱和紫外吸收光谱法研究聚乙烯醇(PEG)和四乙烯五胺(TEPA)与淀粉酶相互作用。结果表明,PEG会增强淀粉酶内源性荧光和酪氨酸残基所处微环境的疏水性;TEPA对淀粉酶内源性荧光的猝灭机制属于动态猝灭,但同时也存在静态猝灭特征,并使色氨酸残基所处微环境的极性增大;在所考察的范围内,PEG与淀粉酶的结合常数在40℃达到最高,TEPA对淀粉酶荧光的动态猝灭结合常数在30℃以上趋于最大,PEG、TEPA与淀粉酶之间的作用力属于疏水与静电作用相结合。     

Pb2+对α-淀粉酶活性的影响及其光谱学研究

在α 淀粉酶介质中加入Pb2 ,通过光谱学手段研究Pb2 对α 淀粉酶活性影响的作用机理。结果表明低浓度的Pb2 对酶有激活作用 ,高浓度则严重抑制酶活性。在高浓度下 ,Pb2 能完全竞争出α 淀粉酶中的Ca2 而结合到了α 淀粉酶上 ,其EXAFS的测试表明Pb2 与氨基酸残基上的羧基氧发生了配位 ,配位数为 2 ,Pb—O键长为 0 2 34nm。圆二色 (CD)谱测试表明 ,高浓度的Pb2 结合使α 淀粉酶的二级结构被破坏 ,α 螺旋含量、β 转角及无规则卷曲大量下降 ,β 折叠、二硫键含量大量增多 ,Pb2 的这种完全结合致使酶的构象改变 ,形成无效的酶 Pb2 底物复合物 ,因而使酶失去活性。     

Behavior of biodegradable composites based on starch reinforced with modified cellulosic fibers

The aims of this study were to develop composite films based on potato starch and cellulose modified with toluenediisocyanate, to investigate their morphology and structure, and to evaluate their behavior to enzymatic hydrolysis and their potential use to manufacture of biodegradable seedling pots. The effects of modified cellulosic fibers upon mechanical properties and biodegradability of composite materials based on starch matrix were investigated by tensile strength tests, Fourier infrared spectroscopy, X‐ray diffraction, and dynamic vapor sorption. The behavior of the films to enzymatic hydrolysis with amylase and cellulase was studied; the kinetic of enzymatic hydrolysis and characterization of materials are reported. Chemical modification of cellulose improves tensile strength with about 47%, and decreases the biodegradability of composites making them more resistant to microbial attack, thus prolonging their shelf life. Copyright © 2015 John Wiley & Sons, Ltd.     

地衣芽孢杆菌1.934培养条件的优化

研究了生物肥功能菌——地衣芽胞杆菌1.934 (Bacillus licheniformis)培养条件对菌体生长量的影响.采用了单因素实验和响应曲面法(RSM)设计实验和分析数据.获得了菌体摇瓶培养的最适条件:培养温度35℃,转速为150r/min,接种量为3.6％,pH为7.5.地衣芽孢杆菌在最适条件下培养约20h,淀粉酶的酶活最高,活力可达12.7U/mL培养液.培养约27h得到最大的菌体收益.     

活性污泥宏基因组Fosmid文库的构建

大插入片段宏基因组文库的构建是开发大片段目的基因及分析其结构与功能的基础.文中分别采用十六烷基三甲基溴化铵(CTAB)法、试剂盒及琼脂糖包埋法提取活性污泥宏基因组DNA,其中琼脂糖包埋法获得的DNA片段大于23kbp,利用此DNA成功构建了以pCC1FOS为载体的Fosmid文库,该文库含有5280个克隆,平均插入片段长度为35～40 kbp,共包含约200 Mbp的宏基因组DNA.从此文库中随机挑选200个克隆,利用活性筛选方法快速筛选到了1个含有淀粉酶的阳性克隆,表明活性污泥Fosmid文库可用于功能基因的活性筛选,具有开发新基因的潜力.     

淀粉酶产生菌的分离筛选

从大米厂、淀粉厂周边环境土壤中筛选到三株产淀粉酶能力较强的菌株Jz1、Jz2、Jz3。经形态特征及染色等初步鉴定,菌株Jz1和Jz3为芽孢杆菌属（Bacillus）,菌株Jz2为短小杆菌属（Curtobacterium）。采用YoungJ.Y00改良法测定此三株菌株的淀粉酶活力分别为47.29 U/mL、48.48 U/mL、49.74 U/mL,具有较好的应用潜力。     

Synthesis,characterization and α‐amylase and α‐glucosidase inhibition studies of novel vanadyl chalcone complexes

A series of chalcone ligands and their corresponding vanadyl complexes of composition [VO (L^I–IV)₂(H₂O)₂]SO₄ (where L^I = 1,3‐Diphenylprop‐2‐en‐1‐one, L^II = 3‐(2‐Hydroxy‐phenyl)‐1‐phenyl‐propenone, L^III = 3‐(3‐Nitro‐phenyl)‐1‐phenyl‐propenone, L^IV = 3‐(4‐Methoxy‐phenyl)‐1‐phenyl‐propenone) have been synthesized and characterized using various spectroscopic (Fourier‐transform infrared, electrospray ionization mass, nuclear magnetic resonance, electron paramagnetic resonance, thermogravimetric analysis, vibrating sample magnetometer) and physico‐analytic techniques. Antidiabetic activities of synthesized complexes along with chalcones were evaluated by performing in vitro and in silico α‐amylase and α‐glucosidase inhibition studies. The obtained results displayed moderate to significant inhibition activity against both the enzymes by vanadyl chalcone complexes. The most potent complexes were further investigated for the enzyme kinetic studies and displayed the mixed inhibition for both the enzymes. Further, antioxidant activity of vanadyl chalcone complexes was evaluated for their efficiency to release oxidative stress using 2,2‐diphenyl‐1‐picryl‐hydrazyl‐hydrate assay, and two complexes (Complexes 2 and 4 ) have demonstrated remarkable antioxidant activity. All the complexes were found to possess promising antidiabetic and antioxidant potential.     

α-淀粉酶产生菌的平板筛选法的研究与改进

用平板水解圈法筛选到若干株 α 淀粉酶产生菌,它们的平板水解圈直径大小与摇瓶酶活不相关,进一步研究了３０ ℃平板淀粉的质量分数对水解圈直径的影响以及淀粉的质量分数、温度、琼脂等多种因素对离体 α 淀粉酶水解圈直径的影响,并在此基础上建立了一种快速筛选高产菌株的简便方法。     

Studies on the Thermodenaturation Behavior of Bacillus subtilis α‐Amylase on Chromatographic Media

The thermodenaturation behavior of Bacillus subtilis α‐amylase on some chromatographic media was studied by determining their adsorption parameters with frontal analysis. The experimental results show that on a RP‐C₁₈ reversed‐phase medium, a Chelating Sepharose Fast‐Flow chelated by Zn²⁺ affinity medium and a WCX‐1 cation‐exchange medium, a stable conformation of α‐amylase molecule separately exists below or over 30 °C; while on a PEG‐400 hydrophobic medium and a modified PEG‐400 medium, a stable conformation of α‐amylase molecule separately exists below 40 and 30 °C, and when the experimental temperatures are separately over 40 and 30 °C, a drastically conformational change of α‐amylase molecules can continuously take place. And by combining the intrinsic fluorescence emission spectrum and thermal inactivation profile of α‐amylase in free solution and on the PEG‐400 and modified PEG‐400 hydrophobic media, it can be concluded that in liquid chromatographic procedure, chromatographic media can induce the conformational change of α‐amylase molecules and promote their thermodenaturation; and in hydrophobic interaction chromatography, the higher the hydrophobicity of chromatographic medium, the lower the conformational change temperature of α‐amylase molecules on the chromatographic medium.     

银杏外种皮提取物浸种对三种植物种子萌发和幼苗生长的影响

本文研究了不同浓度银杏外种皮提取物浸种对小麦、玉米、大豆萌发和幼苗生长的影响.结果表明:低浓度提取物可提高小麦、大豆和玉米种子的萌发率、发芽率;促进幼苗地上和地下部分生长,其中作用最明显的为500倍提取物的稀释液.在萌发期,500倍稀释液浸种液处理:提高小麦和玉米幼苗的淀粉酶和叶绿素的含量,促进大豆幼苗叶绿素和蛋白质含量提高,而高浓度的银杏外种皮提取物稀释液处理则降低小麦和玉米幼苗的淀粉酶和叶绿素的含量,也使大豆幼苗叶绿素和蛋白质含量降低.