Catalytic Mechanism of Short Ethoxy Chain Nonylphenol Dehydrogenase Belonging to a Polyethylene Glycol Dehydrogenase Group in the GMC Oxidoreductase Family

Ethoxy (EO) chain nonylphenol dehydrogenase (NPEO-DH) from Ensifer sp. AS08 and EO chain octylphenol dehydrogenase from Pseudomonas putida share common molecular characteristics with polyethylene glycol (PEG) dehydrogenases (PEG-DH) and comprise a PEG-DH subgroup in the family of glucose-methanol-choline (GMC) oxidoreductases that includes glucose/alcohol oxidase and glucose/choline dehydrogenase. Three-dimensional (3D) molecular modeling suggested that differences in the size, secondary structure and hydropathy in the active site caused differences in their substrate specificities toward EO chain alkylphenols and free PEGs. Based on 3D molecular modeling, site-directed mutagenesis was utilized to introduce mutations into potential catalytic residues of NPEO-DH. From steady state and rapid kinetic characterization of wild type and mutant NPEO-DHs, we can conclude that His465 and Asn507 are directly involved in the catalysis. Asn507 mediates the transfer of proton from a substrate to FAD and His465 transfers the same proton from the reduced flavin to an electron acceptor.     

黄河(兰州段)壬基酚聚氧乙烯醚及其降解产物污染的初步研究

本文以黄河(兰州段)为研究对象,对其流域的4个排污点的水样和6个断面各个介质(包括水体、悬浮颗粒物和沉积物)中壬基酚聚氧乙烯醚(NPnEO)及其降解产物壬基酚的污染进行调查.结果表明,4个排污点水样中分别含有浓度不等的NP;6个断面采样点中,大分子的NPnEO(n>2)在各个介质中均未检出,水样中NP在0.24～2.1...     

城市污水处理厂中NP_nEO的迁移转化

为研究短链壬基酚聚氧乙烯醚（NPnEO,n=1,2）在城市污水处理A/O工艺中的迁移转化行为,采用固相萃取-气相色谱-质谱（SPE-GC-MS）方法测定东北某城市污水处理厂A/O工艺中短链NPnEO（n=1,2）及其代谢产物（NP）在各处理单元水相和污泥相中的含量及分布.污水处理全流程样品分析发现：进水中NP1,2EO...     

Influence of hydrophobe type and extent of branching on environmental response factors of nonionic surfactants

A number of ethoxylated nonionic surfactants differing in hydrophobe branching and chainlengths have been evaluated for environmental responses. Screening biodegradation tests show that those nonionics having more than one methyl group per hydrophobe degrade considerably slower than those having less extensive branching. Continuous flow-through activated sludge tests, simulating actual waste treatment, show that the more highly branched nonionics biodegrade more slowly and less extensively than those with less hydrophobe branching. In addition, treated effluents originating from influents containing the more highly branched nonionics tend to be more surface active and more toxic to aquatic species than those originating from influents containing surfactants with less hydrophobe branching. Under conditions simulating plant stress, such as high surfactant concentrations in the influent or low temperature, biodegradation of the highly branched nonionics was considerably less extensive, while biodegradation of the linear nonionics was not affected to any measurable degree compared to more normal operating conditions. Presented at the 81st American Oil Chemists’ Society Annual Meeting, April 22–26, 1990, Baltimore, Maryland.     

壬基酚为原料合成双季铵盐

根据Mannich反应原理 ,用壬基酚、二乙胺、甲醛为原料 ,合成Mannich碱 双叔胺 2 ,6 二 (二乙胺基甲基 ) 4 壬基酚 (BDN) ,研究了BDN合成工艺 ,优化反应条件为 :乙醇为溶剂 ,反应温度30℃ ,投料比n (壬基酚 )∶n(甲醛 )∶n(二乙胺 ) =1 0∶3 0∶3 0。用IR、质谱和液相色谱分析了BDN的结构和含量。利用其与 3种烷基化试剂—溴乙烷、氯化苄、环氧氯丙烷分别反应合成了 3种双季铵盐WYB、WYC及WYO ,并对合成的 3种季铵盐阳离子表面活性剂的表面活性进行了测定。结果表明 :WYB、WYC及WYO均能显著降低水溶液的表面张力 ,γCMC都在 30mN/m以下     

Occurrence and biodegradation of nonylphenol in the environment

Nonylphenol (NP) is an ultimate degradation product of nonylphenol polyethoxylates (NPE) that is primarily used in cleaning and industrial processes. Its widespread use has led to the wide existence of NP in various environmental matrices, such as water, sediment, air and soil. NP can be decreased by biodegradation through the action of microorganisms under aerobic or anaerobic conditions. Half-lives of biodegradation ranged from a few days to almost one hundred days. The degradation rate for NP was influenced by temperature, pH and additions of yeast extracts, surfactants, aluminum sulfate, acetate, pyruvate, lactate, manganese dioxide, ferric chloride, sodium chloride, hydrogen peroxide, heavy metals, and phthalic acid esters. Although NP is present at low concentrations in the environment, as an endocrine disruptor the risks of long-term exposure to low concentrations remain largely unknown. This paper reviews the occurrence of NP in the environment and its aerobic and anaerobic biodegradation in natural environments and sewage treatment plants, which is essential for assessing the potential risk associated with low level exposure to NP and other endocrine disruptors.     

壬基酚聚氧乙烯醚丙基磺酸钠的表面活性及应用性能

研究了硬水和油田水中壬基酚聚氧乙烯醚丙基磺酸钠(NPSO-5)水溶液的表面活性及应用性能,并与常用表面活性剂LAS、AOS和AES进行比较;考察了添加脂肪醇对NPSO-5体系泡沫性能的影响和NPSO-5在NaOH水溶液中的润湿性能及硬水溶液中的润湿乳化性能。结果表明,水硬度从0 mmol/L增加到80 mmol/L,NPSO-5的临界胶束浓度(CMC)从2.06×10-4 mol/L降低到7.8×10-5 mol/L;NPSO-5相对于LAS和AOS具有较强的抗硬水能力,且在硬水中具有较高的起泡能力和稳泡性能,添加脂肪醇在一定程度上改变了液膜吸附层的结构,进一步提高了体系的泡沫性能;在NaOH质量分数达12%时,NPSO-5仍然具有良好的润湿性能。     

壬基酚在食品中的污染现状及其生物毒性概述

壬基酚是一种内分泌干扰物,其对食品的污染正引起人们的广泛关注.对壬基酚的性质与应用,在食品中的污染水平,主要来源以及对生物体的毒害作用等进行了综述,可为我国开展壬基酚的风险评估与限量制定等研究提供参考.     

蜡状芽抱杆菌壬基苯酚降解酶的分离纯化及其酶学性质(英文)

An extracellular NP-degrading enzyme secreted by Bacillus cereus.Frankland was purified to homogeneity by a combination of ammonium sulfate precipitation,Phenyl-Sepharose hydrophobic-interaction chromatography and DEAE anion-exchange chromatography.On SDS(sodium dodecyl sulfate)-polyacrylamide gel electrophoresis analysis,the purified enzyme showed a relative molecular mass of 58.3 kDa.The depolymerzation of subunits was accompanied with the loss of NP-degrading enzyme activity,and removing denaturing factors by dialysis could restore the dimer structure and enzymatic activity.The enzyme had an isoelectric point of 5.5 and an optimal temperature of 60℃,and was the most active at pH 6.0.The enzymatic activity was stable at pH 4-8 and inhibited by Cu2+.TenN-terminal amino acids were determined to be ASVNSIKIGY,demonstrating that the purified enzyme was a novel one.The hydrolysis pattern of the purified enzyme indicated that the NP-degrading enzyme was an endo NP-degrading enzyme.The extraordinary thermo-stability provided the enzyme with a good prospect to be used as a new tool for clean-production process for textile industry.