不同条件对胰蛋白酶水解酪蛋白水解度的影响

研究了不同温度和水解时间以及不同浓度的SDS对胰蛋白酶水解酪蛋白水解度的影响.结果表明：在酪蛋白浓度为4%、加酶量2 500 U/g、pH为7的条件下,选择温度为50℃,水解时间为80 min,酪蛋白的水解效果较佳,水解度为7.30%;同等条件下向此体系加入适量的SDS后,使SDS终浓度为0.001 28 g/mL,水解度提高为13.50%.     

碱性苦味酸法和酶法测血清肌酐的方法学比较

[目的]了解酶法和碱性苦味酸法测定血清肌酐结果的偏倚大小,对两种方法进行比较.[方法]用生化仪器OLYMPUSAU1000分别进行酶法和碱性苦味酸法测定血清肌酐.对两种方法进行重复性实验、相关性实验、线性比较和回收试验.[结果]酶法和碱性苦味酸法的重复性实验数据(x±s)266±2.77μmol／L和273.5±3.30μmol／L,其变异系数分别为1.04％、1.21％;两者的回归方程式yJaffe=1.01X二步酶法-1.28;酶法的线形范围远大于碱性苦味酸法;在回收试验中两者的回收率分别为98.5％、94.5%.[结论]酶法和苦味酸法有较好的相关性,酶法比碱性苦味酸法线性范围宽,特异性和灵敏度高,测定重复性好,是比较理想的方法.临床上酶法将逐渐代替苦味酸法测定血清肌酐.     

草菇保健饮料的研制

以蘑菇为原料,使用柠檬酸、维生素C等药剂进行各种处理,对提取所用的温度、时间,所用的药剂等因素进行适度调整、比较,确定提取工艺的最佳条件,并配制出营养,保健,绿色的食用菌饮料。     

Flavourzyme风味酶水解鸭蛋蛋清研究

利用Flavourzyme风味酶水解鸭蛋蛋清，测定其不同水解度水解产物的特性，包括水溶性、热稳定性和乳化性。结果表明：随着加入酶水平的提高和反应时间延长，水解度不断增加；水解物的可溶性氮含量随水解度的增加而增高，受到溶液pH变化影响逐步减小；水解物的热稳定性增加；蛋清蛋白经过适度的水解，其乳化性稍有增加，但是随着水解度的增大，乳化性降低。     

高压水解处理氧化乐果废水研究

The effect of pressure on the hydrolysis rates and the degradation kinetics of environmentally persistent omethoate pesticide was studied. The results showed that the values of kobs increased and the values of activation volume (AV) decreased with increasing pressure. Among pH conditions (3.58, 6.01 and 8.5), pH 8.5 was found to be the unstable condition and its half-life was reduced from 263 min at 1 atm to 19.37 min at 10 atm. These results describe that high-pressure hydrolysis is a useful technique for the conversion of toxic organic phosphorus into inorganic phosphorus.     

电化学法测定西维因水解速率参数

使用现代电化学分析方法,通过监测水解产物的生成情况,研究了本身无电化学活性的西维因(甲萘威)在水中的水解情况,在pH=7.0的BR缓冲液环境中西维因水解产物检测的灵敏度最高.考察了环境酸度以及环境温度对水解的影响,并测定了不同条件下的水解速率常数.发现西维因的水解过程符合一级反应方程,其水解受pH值、温度的影响.在酸性介质中西维因仍有一定的水解,但是水解的速率明显低于碱性介质中的水解速率.同时,环境温度也会影响水解速率,在较高温度下,不论环境酸度值为碱性或者酸性,西维因的水解速率均有所升高.     

Kinetics of non-catalyzed hydrolysis of tannin in high temperature liquid water

High temperature liquid water (HTLW) has drawn increasing attention as an environmentally benign medium for organic chemical reactions,especially acid-/base-catalyzed reactions.Non-catalyzed hydrolyses of gallotannin and tara tannin in HTLW for the simultaneous preparation of gallic acid (GA) and pyrogallol (PY) are under investigation in our laboratory.In this study,the hydrolysis kinetics of gallotannin and tara tannin were determined.The reaction is indicated to be a typical consecutive first-order one in which GA has formed as a main intermediate and PY as the final product.Selective decomposition of tannin in HTLW was proved to be possible by adjusting reaction temperature and time.The present results provide an important basic data and reference for the green preparation of GA and PY.     

Nutritional evaluation of caseins and whey proteins and their hydrolysates from Protamex

Whey protein concentrate （WPC 80） and sodium caseinate were hydrolyzed by Protamex to 5%, 10%, 15%, and 20% degree of hydrolysis （DH）. WPC 80, sodium caseinate and their hydrolysates were then analyzed, compared and evaluated for their nutritional qualities. Their chemical composition, protein solubility, amino acid composition, essential amino acid index （EAA index）, biological value （BV）, nutritional index （NI）, chemical score, enzymic protein efficiency ratio （E-PER） and in vitro protein digestibility （IVPD） were determined. The results indicated that the enzymatic hydrolysis of WPC 80 and sodium caseinate by Protamex improved the solubility and IVPD of their hydrolysates. WPC 80, sodium caseinate and their hydrolysates were high-quality proteins and had a surplus of essential amino acids compared with the FAO/WHO/UNU （1985） reference standard. The nutritive value of WPC 80 and its hydrolysates was superior to that of sodium caseinate and its hydrolysates as indicated by some nutritional parameters such as the amino acid composition, chemical score, EAA index and predicted BV. However, the E-PER was lower for the WPC hydrolysates as compared to unhydrolyzed WPC 80 but sodium caseinate and its hydrolysates did not differ significantly. The nutritional qualities of WPC 80, sodium caseinate and their hydrolysates were good and make them appropriate for food formulations or as nutritional supplements.     

复合蛋白酶水解罗非鱼条件的优化研究

以水解度为优化的指标,利用单因素试验研究酶解温度、pH值、反应时间等因素对鱼蛋白水解的影响,利用中心组合试验方法优化酶的添加量和蛋白质浓度．结果表明：复合蛋白酶水解罗非鱼的最佳条件为：加酶量17660U／g蛋白、蛋白质质量分数2．50％、水解温度55℃、pH值7．5、水解时间10h,在此条件下,水解体系的氨基酸态氮含量达到了1．41mg／mL,水解度为35．25％,挥发性盐基氮含量为0．048mg／mL,得到用复合蛋白酶水解罗非鱼的最佳工艺条件．     

蛋白酶水解鳕鱼粉条件的研究

对比研究pH、水解温度、时间、底物浓度、产物浓度等条件因子对4种商品蛋白酶水解鳕鱼粉的影响,为利用蛋白酶水解鳕鱼粉提供理论基础.试验结果表明:碱性蛋白酶水解鳕鱼粉的适宜pH为8.0,温度为45℃,时间为20 min,鳕鱼粉浓度为6%,氨基酸含量不超过1.95 mg.mL-1;复合蛋白酶水解鳕鱼粉的适宜pH为6.5,温度为50℃,时间为25 min,鳕鱼粉浓度为6%,氨基酸含量不超过2.08 mg.mL-1;中性蛋白酶水解鳕鱼粉的适宜pH为7.0,温度为40℃,时间为20 min,鳕鱼粉浓度为6%~8%,氨基酸含量不超过2.29mg.mL-1;酸性蛋白酶水解鳕鱼粉的适宜pH为3.0,温度为40℃,时间为20 min,鳕鱼粉浓度为6%~8%,氨基酸含量不超过2.82 mg.mL-1.     

复合蛋白酶水解蓝圆鳆工艺条件的优化

以水解度为优化指标,利用单因素试验考察酶解温度、pH值、时间等因素对鱼蛋白水解的影响,利用中心组合试验方法优化酶的添加量和蛋白质浓度．结果表明,复合蛋白酶水解蓝圆够的最佳工艺条件为：加酶量2700U·g^-1蛋白、蛋白质浓度1．56％、水解温度60℃、反应体系pH7．5、反应时间8h．在此条件下,水解体系的氨基酸态氮含量达1．27mg·mL^-1,水解度为50．98％,挥发性盐基氮含量为0．032mg·mL^-1。     

在反思性化学教学中培养学生提出问题的能力——以苏教版化学反应原理“盐类水解”为例

在学生问题意识现状调查基础上,探讨在反思性化学教学中培养学生提出问题能力的几个途径。     

High-level soluble expression of the hemA gene from Rhodobacter capsulatus and comparative study of its enzymatic properties

The Rhodobacter capsulatus hemA gene, which encodes 5-aminolevulinic acid synthase (ALAS), was expressed in Escherichia coli Rosetta (DE3) and the enzymatic properties of the purified recombinant ALAS (RC-ALAS) were studied. Compared with ALASs encoded by hemA genes from Agrobacterium radiobacter (AR-ALAS) and Rhodobacter sphaeroides (RS-ALAS), the specific activity of RC-ALAS reached 198.2 U/mg, which was about 31.2% and 69.5% higher than those of AR-ALAS (151.1 U/mg) and RS-ALAS (116.9 U/mg), respectively. The optimum pH values and temperatures of the three above mentioned enzymes were all pH 7.5 and 37 °C, respectively. Moreover, RC-ALAS was more sensitive to pH, while the other two were sensitive to temperature. The effects of metals, ethylene diamine tetraacetic acid (EDTA), and sodium dodecyl sulfate (SDS) on the three ALASs were also investigated. The results indicate that they had the same effects on the activities of the three ALASs. SDS and metal ions such as Co²⁺, Zn²⁺, and Cu²⁺ strongly inhibited the activities of the ALASs, while Mn²⁺ exerted slight inhibition, and K⁺, Ca²⁺, Ba²⁺, Mg²⁺, or EDTA had no significant effect. The specificity constant of succinyl coenzyme A [(k _cat/K _m)_S-CoA] of RC-ALAS was 1.4989, which was higher than those of AR-ALAS (0.7456) and RS-ALAS (1.1699), showing its high catalytic efficiency. The fed-batch fermentation was conducted using the recombinant strain containing the R. capsulatus hemA gene, and the yield of 5-aminolevulinic acid (ALA) achieved was 8.8 g/L (67 mmol/L) under the appropriate conditions.     

碱性蛋白酶制备纳米珍珠粉工艺优化

使用碱性蛋白酶处理,考察摇床转速、酶解时间和加酶量对纳米级珍珠粉得率的影响．试验结果表明：10g珍珠粉加入50mL去离子水,在摇床转速为180r／rain、酶解时间为8h、酶用量为0．5g时,纳米级珍珠粉得率为95．2％．凯式定氮实验表明：酶解前后珍珠粉蛋白质的含量分别为24．132％和22．010％,酶解后仅相对减少了0．088．     

AFEX预处理玉米秸秆条件优化的试验研究

以玉米秸秆为生物质原料,进行了AFEX预处理试验,然后添加纤维素酶和淀粉酶进行酶解,并利用高效液相色谱(HPLC)测定了生物质中的单糖含量。研究结果表明,在含水率为80%,温度为90℃,纤维素酶添加量为15FPU时,葡萄糖和木糖的总转化率分别为92.14%和67.06%。结果表明AFEX处理对玉米秸秆是一种有效的预处理方式,研究成果对生物质转化和利用提供理论依据。     

公民环境知情权法律制度探析

环境权是公民环境知情权的权利来源,环境知情权是公民参与环境保护的前提条件。应该构建和完善我国公民环境知情权法律制度,以求在实践中把公民环境知情权落到实处,为公民参与环境保护创造条件,同时也为公民保护自己合法的环境权益奠定良好的基础。     

生物催化反应在工业生产中的应用

本文通过生物催化反应的几种类型简单介绍了生物催化剂－酶应用于工业生产的情况。     

Fusion expression of pedA gene to obtain biologically active pediocin PA-1 in Escherichia coli

Two heterologous expression systems using thioredoxin (trxA) as a gene fusion part in Escherichia coli were developed to produce recombinant pediocin PA-1. Pediocin PA-1 structural gene pedA was isolated from Pediococcus acidilactici PA003 by the method of polymerase chain reaction (PCR), then cloned into vector pET32a(+), and expressed as thioredoxin-PedA fusion protein in the host strain E. coli BL21 (DE3). The fusion protein was in the form of inclusion body and was refolded before purification by nickel-iminodiacetic acid (Ni-IDA) agarose resin column. Biological activity of recombinant pediocin PA-1 was analyzed after cleavage of the fusion protein by enterokinase. Agar diffusion test revealed that 512-arbitrary unit (AU) recombinant pediocin PA-1 was obtained from 1 ml culture medium of E. coli (pPA003PED1) using Listeria monocytogenes as the indicator strain. Thioredoxin-PedA fusion gene was further cloned into pET20b(+). Thioredoxin-PedA fusion protein was detected in both the periplasmic and cytoplasmic spaces. The recombinant pediocin PA-1 from the soluble fraction attained 384 AU from 1 ml culture medium of E. coli (pPA003PED2). Therefore, biologically active pediocin PA-1 could be obtained by these two hybrid gene expression methods.     

辅助方程法求变系数Boussinesq方程的精确解

以辅助方程法为基础,结合函数变换,借助符号计算系统Mathematica构造变系数Boussinesq方程的新的类孤子解和三角函数波解。     

The transition from higher education to employment in Europe: the analysis of the time to obtain the first job

This paper investigates the determinants of the transition from higher education to work across Europe using various specifications of duration models and a one-time multi-country survey of university graduates from nine European countries. Results point to differences between the North and South of Europe in the difficulty of getting a first job. They confirm that individual characteristics such as the field/level of studies or the socioeconomic background, and individual job search bear a significant relationship to the probability of finding a job. Evidence of unobserved heterogeneity is also found.