金属离子对羊血超氧化物歧化酶活性的影响

以离子交换层析法制备的羊血SOD(Superoxide dismutase)为原料,加入不同浓度的Na+、K+、Ba2+、Ca2+、Mg2+、Zn2+、Cu2+、Fe2+等金属离子,25℃保温4h后,利用邻苯三酚自氧化法测定SOD酶活力,并计算相对酶活力。结果表明:不同金属离子在不同浓度下对羊血SOD酶活的影响不同。Na+对SOD酶活影响不大;K+、Ca2+、Fe2+在体外对羊血SOD具有激活作用,且Fe2+作用明显,相对酶活力可达378.98%;Ba2+、Mg2+在低浓度下对SOD影响不大,在高浓度下有一定的激活作用,但不同浓度激活效果不同;Zn2+、Cu2+在体外对羊血SOD表现有抑制作用,但二者的抑制程度不同。     

助剂对纺织用α-淀粉酶热稳定性影响的研究

考察了纺织用α-淀粉酶的最适pH及最适温度,研究了多种金属离子、醇类、糖类以及不同分子质量的聚乙二醇对α-淀粉酶酶活力及热稳定性能的影响.结果表明,在金属离子中,K<'+>对提高酶的活力及热稳定效果最好;在醇类物质中,甘油和D-山梨醇的作用效果最好;在糖类物质中,葡萄糖和海藻糖效果最好;分子质量为200、400、600的聚乙二醇能提高α-淀粉酶的活力及热稳定性.与α-淀粉酶相比较,加入了氯化钾、甘油、D-山梨醇、葡萄糖、海藻糖的α-淀粉酶的最适温度从43.3℃提高到60℃,表明助剂能有效提高纺织用α-淀粉酶的热稳定性能.     

不同碳源对黑曲霉产糖化酶活力的影响

碳源对黑曲霉产糖化酶活力有很大影响。研究可溶性淀粉、葡萄糖、蔗糖、麦芽糖、乳糖和β-环糊精为碳源时,分别对黑曲霉产糖化酶活力的影响。结果表明,可溶性淀粉为碳源时酶活力最高,最高可达350．34&#177;14．06U／ml;其次是葡萄糖;蔗糖和麦芽糖为碳源时酶活力没有显著性差异;乳糖为碳源时酶活力低于蔗糖和麦芽糖;β-环糊精的酶活力最低。不同碳源发酵培养基中生物量研究表明,黑曲霉能充分利用可溶性淀粉、葡萄糖、蔗糖和麦芽糖,对乳糖的利用较差,几乎不能利用β-环糊精。     

水飞蓟油的体外抗氧化活性及对氧化损伤小鼠的保护作用

目的：研究水飞蓟油的体外抗氧化活性及其对D-半乳糖氧化损伤小鼠的保护作用。方法：通过测定水飞蓟 油对二苯基苦味酰基苯肼自由基、羟自由基的清除能力及其总抗氧化力,研究其体外抗氧化活性;通过测定水飞蓟 油对氧化损伤小鼠血清抗氧化酶活力以及其对小鼠肝组织形态的影响,研究其对氧化损伤小鼠的保护作用。结果： 水飞蓟油具有一定的体外抗氧化能力,并与其质量浓度呈一定的正相关关系;水飞蓟油可显著提高小鼠血清中超氧 化物歧化酶和谷胱甘肽过氧化物酶的活力及总抗氧化能力,可以保护小鼠肝细胞形态的完整性。结论：水飞蓟油具 有一定的体外抗氧化活性,对D-半乳糖氧化损伤小鼠具有明显的保护作用。     

碳源对Bacillus cereus CZ氨肽酶产量及糖代谢酶活性的影响

本文对Bacillus cereus CZ生产亮氨酸氨肽酶(LAP)进行了研究。结果表明,L-阿拉伯糖最利于LAP生产,D-半乳糖和乳糖也有较好效果,葡萄糖、麦芽糖、蔗糖或碳酸氢钠则强烈抑制LAP产生。L-阿拉伯糖和单糖混合、乳糖或半乳糖与葡萄糖混合均大大降低LAP产量。乳糖、葡萄糖有利于细胞生长。2%的乳糖、半乳糖或阿拉伯糖作为碳源,发酵48 h时LAP产量并没有达到最高。对于三种糖代谢酶,β-半乳糖苷酶受乳糖强烈诱导,D-半乳糖则强烈抑制该酶的活性,半乳糖激酶受D-半乳糖强烈诱导。L-阿拉伯糖异构酶受L-阿拉伯糖强烈诱导。当L-阿拉伯糖和半乳糖的浓度为4%时,LAP产量达到最高。胞外半乳糖激酶随D-半乳糖增加而降低,而胞内正好相反。L-阿拉伯糖异构酶活性随L-阿拉伯糖浓度增加而增加。当L-阿拉伯糖为4%时,LAP产量在发酵56 h达到最高,但在半乳糖为4%时,LAP产量随时间延长而增加。     

山楂提取物对D-半乳糖致衰小鼠抗氧化系统的影响

探讨山楂提取物对D-半乳糖致衰小鼠抗氧化系统的影响.选用Babl/C小鼠,在注射D-半乳糖的同时,灌胃低、中、高3种不同剂量的山楂提取物,6周后测定小鼠血清中超氧化物歧化酶(SOD)的活性,以及肝组织中SOD、谷胱甘肽过氧化物酶(GSH-Px)、过氧化氢酶(CAT)的活性.与衰老模型对照组相比,灌胃山楂提取物中、高剂量组的小鼠血清SOD、肝组织CAT活性显著升高(P<0.01),肝组织SOD、GSH-Px活性也有明显升高(P<0.05).     

刺参内脏蛋白酶解液抗氧化活性研究

采用小鼠D-半乳糖致衰老模型,通过测定小鼠肝脏和心脏中的超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)活性和丙二醛(MDA)含量,进一步研究了刺参内脏蛋白酶解物酶解物的抗氧化活性。表明灌胃200 mg/kg·d酶解物可明显提高小鼠肝脏和心脏中SOD和GSH-Px活力,并显著降低MDA含量。说明刺参内脏蛋白酶解物在一定程度上能够提高D-半乳糖模型衰老小鼠的抗氧化能力。     

串叶松香草超氧化物歧化酶提取工艺优化及对D-半乳糖致衰老模型小鼠的保护作用研究

目的 优化串叶松香草超氧化物歧化酶(superoxide dismutase, SOD)的提取工艺, 并研究串叶松香草SOD对D-半乳糖致衰老模型小鼠的保护作用。方法 采用高压脉冲电场法提取SOD, 以串叶松香草为原料, 进行最佳提取工艺的研究, 以SOD酶活力为指标, 在单因素实验基础上, 进一步通过响应面实验对提取工艺进行优化。同时采用随机法把小鼠分为空白对照组、模型组、串叶松香草SOD低、中、高剂量组、维生素C (vitamin C, VC)阳性对照组。除空白对照组外, 其余5组均皮下连续注射D-半乳糖, 采用注射D-半乳糖构建衰老小鼠模型。通过观察和测定各组小鼠的行为和体质量, 研究其衰老的变化情况; 采用分光光度计法测定小鼠血清中SOD、谷胱甘肽过氧化物酶(glutathione peroxidase, GSH-Px)、过氧化氢酶(catalase, CAT)活性和丙二醛(malondialdehyde, MDA)含量。结果 最佳提取工艺条件为: 电场强度20 kV/cm、脉冲数10个、提取时间32 min, 在此条件下, 提取的串叶松香草SOD酶活力为3878.67 U/g。串叶松香草SOD对D-半乳糖致衰老模型小鼠的抗衰老作用表明: 串叶松香草SOD能改善衰老小鼠的体征, 提高衰老小鼠的体质量, 具有较好的抗肝萎缩和脑萎缩作用, 同时还能提高衰老小鼠血清中SOD、GSH-Px、CAT的活力, 降低其MDA含量, 达到延缓衰老的作用。结论 该研究获得了串叶松香草SOD的最佳提取工艺, 得到的串叶松香草SOD能够延缓小鼠衰老。     

黄秋葵果实粉对衰老模型小鼠抗氧化能力的影响

探讨黄秋葵果实粉(OFP)对D-半乳糖致衰老模型小鼠抗氧化能力的影响。以昆明种小鼠为研究对象,颈背部皮下注射D-半乳糖造模。正常对照组、模型对照组饲喂基础饲料,实验组小鼠饲喂含受试物低、中、高剂量(32.00、64.00、128.00 g/kg)饲料,实验期56 d,测定血清和肝组织匀浆中超氧化物岐化酶(SOD)、谷胱苷肽过氧化物酶(GSHPx)、过氧化氢酶(CAT)的活性及丙二醛(MDA)的含量。D-半乳糖致衰小鼠SOD活性、GSH-Px活性和CAT活性均明显下降,MDA含量明显上升,与正常小鼠比较差异显著;饲喂不同剂量的黄秋葵果实粉后均能提高小鼠血清、肝脏组织中的SOD、GSH-Px和CAT活性,同时降低血清、肝脏组织中MDA含量。适量摄入黄秋葵果实粉能显著提高衰老小鼠的抗氧化能力,具有一定延缓衰老的作用。     

两种甜叶菊废渣提取物对D-半乳糖致衰老小鼠的抗氧化作用

目的:研究两种甜叶菊废渣提取物对D-半乳糖致衰老小鼠的抗氧化作用。方法:80只小鼠随机被分为正常组、D-半乳糖组、两种甜叶菊废渣提取物低、中、高剂量组(100,200,500 mg/kg bw)。采用颈背部皮下注射D-半乳糖(500 mg/kg bw)构建衰老模型,正常组颈部皮下注射等体积的生理盐水,样品组同时给予不同剂量的甜叶菊废渣提取物。持续11周后,测定小鼠血清、肝脏和脑组织中的超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GPx)的活性和丙二醛(MDA)的含量,以及脑组织中抗氧化酶基因的相对表达量。结果:与D-半乳糖组相比,两种甜叶菊废渣提取物均在不同程度上提高小鼠血清、肝和脑抗氧化酶(SOD和GPx)的活力,降低MDA含量,且在高剂量时(500 mg/kg bw)效果最为显著。两种甜叶菊废渣提取物高剂量组小鼠脑组织中抗氧化酶基因(Nrf-2,SOD1,GPx1,HO-1)的相对表达量显著增加。结论:两种甜叶菊废渣提取物通过促进抗氧化酶基因表达,增加D-半乳糖致衰老小鼠体内相关抗氧化酶的活力并减少氧化损伤产物MDA的含量,具有潜在的延缓衰老的作用。     

3 种食用菌菌丝体富钙的研究

通过对白灵菇(Pleurotus nebrodensis)、杏鲍菇(Pleurotus eryngii)、榆黄菇(Pleurotus citrinopileatus Sing)3 种食用菌以氯化钙为钙源进行平板固体富钙培养,发现不同菌种、不同碳源、不同钙浓度对其富钙均有较大影响。在相同的培养基上,白灵菇富钙量高于榆黄菇,杏鲍菇富钙量最低;在不同碳源的培养基上,3 种食用菌菌丝富钙量为乳糖培养基高于麦芽糖培养基,蔗糖培养基最低;白灵菇在乳糖培养基中培养,钙浓度(以Ca2+ 计)为0.6% 时富钙量最高。     

OPTIMIZATION OF ENZYMATIC SYNTHESIS OF ISOMALTO-OLIGOSACCHARIDES PRODUCTION

Glucosyltransferases can be applied in the synthesis of prebiotic oligosaccharides. Enzymatic synthesis using acceptors can be used to obtain these carbohydrates. When maltose is the acceptor, oligosaccharides containing one maltose moiety and up to eight glucose units linked by α-1,6-glycosidic bonds are obtained as the product of dextransucrase acceptor reaction. In this work, the enzymatic synthesis of isomalto-oligosaccharides using dextransucrase from Leuconostoc mesenteroides NRRL B-512F was optimized by response surface methodology. The effect of maltose and sucrose concentrations on the acceptor reaction was evaluated in a batch reactor system. Partially purified enzyme was used to reduce the enzyme purification cost. The results showed that high sucrose concentrations in conjunction with high maltose levels enhanced the isomalto-oligosaccharide synthesis. A productivity of 42.95 mmol/L.h of isomalto-oligosaccharides was obtained at the optimal operating condition (100 mmol/L of sucrose and 200 mmol/L of maltose).

PRATICAL APPLICATIONS

Oligosaccharides as prebiotic have a large application in food formulations, and their beneficial role in human health have been extensively studied. Although the acceptor mechanism of dextransucrase has already been extensively studied, an industrial process has not been developed yet for enzyme synthesis of isomalto-oligosaccharide. The process studied in this work allows the large-scale preparation of isomalto-oligosaccharide using partially purified enzyme.     

Enzymatic synthesis of myristoyl disaccharides and their surface activity

The condensation of trehalose, maltose, cellobiose, sucrose, turanose, palatinose, lactose and melibiose with myristic acid by a lipase (triacylglycerol acylhydrolase; EC 3.1.1.3) from Candida antarctica was examined at 60 °C in a mixture of pyridine and 2‐methyl‐2‐propanol (20/80 by vol.). The reactivity of trehalose was the highest among the tested disaccharides, and maltose and palatinose followed. Cellobiose and lactose were poor substrates for condensation. Condensation of all the disaccharides except for cellobiose and lactose with myristic acid was carried out at various initial disaccharide concentrations to estimate the initial reaction rate. Plots of the initial rates for monomyristoyl disaccharide formation versus the initial disaccharide concentration normalized by the solubility of the disaccharide in the mixture indicated that palatinose was the best substrate, and that trehalose, turanose and maltose were the next best ones. The surface activity of the monoacyl disaccharides scarcely depended on the type of disaccharide. Copyright © 2007 Society of Chemical Industry     

不同碳源对黄伞菌丝生长的研究

采用平板培养和液体培养的方法研究不同碳源及其浓度对黄伞菌丝生长和胞外多糖产量的影响。结果表明：适宜黄伞菌平板培养菌丝的碳源及其浓度为：果糖 2.5%、麦芽糖3.0%、葡萄糖 3.0%、乳糖 3.0%、红糖2.5%、蔗糖2.5%;最适宜黄伞菌液体培养菌丝体的碳源为3.0% 的葡萄糖,最适宜黄伞菌产生胞外多糖的碳源为2.0% 的麦芽糖。     

白地霉Cryytococcus neo formans ch-3冷冻干燥保护剂的选择

以海藻糖、乳糖、麦芽糖、半乳糖、蔗糖、甘露糖、山梨糖、山梨醇、木糖作为1株产低温脂肪酶的白地霉ch-3的冷冻干燥保护剂。研究表明,海藻糖为最佳保护剂,菌体存活率可达75%以上,其次是蔗糖、乳糖、麦芽糖、山梨糖。对冻干前后及未加保护剂的菌体作电镜观察表明,海藻糖对菌体有很好的保护作用。     

Statistical Modeling of β-galactosidase Inhibition During Lactose Hydrolysis

A statistical model approach called response surface methodology was used to describe the product and substrate inhibition effect on β-galactosidase enzyme during lactose hydrolysis. The effect of independent variables, namely the initial concentrations of lactose (73 - 146 mM), galactose (44 - 122 mM) and glucose (83 - 167 mM) on the reaction rate of β-galactosidase was evaluated. The enzymatic reaction rate was influenced by both combined and individual effects of all the substrate and products. Although, glucose acted as an activator at low lactose and low galactose concentrations, glucose caused the inhibition of β-galactosidase at higher concentrations of lactose and galactose. The effect of galactose concentration on β-galactosidase enzyme was in the direction of inhibition. At low lactose concentrations and high glucose concentrations, galactose concentration became more effective on the reaction rate.     

Statistical Modeling of β-galactosidase Inhibition During Lactose Hydrolysis

A statistical model approach called response surface methodology was used to describe the product and substrate inhibition effect on β-galactosidase enzyme during lactose hydrolysis. The effect of independent variables, namely the initial concentrations of lactose (73 – 146 mM), galactose (44 – 122 mM) and glucose (83 – 167 mM) on the reaction rate of β-galactosidase was evaluated. The enzymatic reaction rate was influenced by both combined and individual effects of all the substrate and products. Although, glucose acted as an activator at low lactose and low galactose concentrations, glucose caused the inhibition of β-galactosidase at higher concentrations of lactose and galactose. The effect of galactose concentration on β-galactosidase enzyme was in the direction of inhibition. At low lactose concentrations and high glucose concentrations, galactose concentration became more effective on the reaction rate.     

Characterization of Physical and Mechanical Properties of Miscible Lactose‐Sugars Systems

Lactose‐sugars systems were produced by spray drying. They were lactose, lactose–glucose (4:1) mixtures, lactose–maltose (4:1) mixtures, lactose–sucrose (4:1) mixtures, lactose–trehalose (4:1) mixtures, and lactose–corn syrup solids (CSS) (4:1) mixtures. The physical characteristics, water sorption behavior, glass transition, and mechanical properties of miscible lactose‐sugars systems were investigated. Lactose–glucose mixtures had larger particle size than other lactose‐sugars systems after spray drying. The presence of glucose or sucrose in lactose‐sugars mixtures decreased the glass transition temperatures of amorphous systems, while the presence of maltose and trehalose had only minor impact on the glass transition temperatures. Moreover, glucose accelerated the crystallization of amorphous system at 0.44 a_w, but its presence delayed the loss of sorbed water at higher water activities (≥0.54 a_w). Mechanical property study indicated that glucose and sucrose in amorphous system could result in an increase of molecular mobility, while the presence of CSS could decrease the free volume and maintain the stiffness of the miscible systems.     

麦芽糖转糖基酶产环糊精性质的研究

通过β-淀粉酶对未环化的直链淀粉进行降解,采用DNS法对反应体系中还原糖进行测定,依据环化反应前后还原糖的变化来计算环糊精的产率,研究底物浓度、酶量、温度、pH、麦芽糖、乙醇、二甲基亚砜对转化率的影响。结果表明,直链淀粉终浓度为0.1～0.125%时转化率最高,而酶用量对最终转化率影响不大,最适转化pH值和温度分别是6.5和40℃,麦芽糖对转化率起抑制作用,乙醇和二甲基亚砜则能够提高转化率。     

金属离子对重组N-乙酰鸟氨酸脱乙酰基酶可溶部分酶活力的影响

重组N-乙酰鸟氨酸脱乙酰基酶可在重组菌BL21-pET22b-argE中高效表达,大多以不可溶的包涵体形式存在。文中研究了金属离子浓度及添加时间对该菌生长及可溶表达部分酶活力的影响。结果表明,1.0g/L的Mg2+对生物量和酶活有明显促进作用。Co2+的浓度及添加时间不同,对菌的生长及酶活力的影响结果也不同。培养起始加入Co2+会抑制菌的生长及酶活,而在1.0%乳糖诱导2.5h后加入则可解除生长抑制并促进酶活。Ni2+,Cu2+会抑制菌体的生长及酶活。Mn2+、Mo2+和B3+不影响菌的生长,对酶活有促进作用。添加金属离子后,酶活从16.90U/mL提高到251.91U/mL。