Up to 25% of the current pesticides are chiral, the molecules have chiral centers, but most of them are used as racemates. In most cases, enantiomers of chiral pesticides have different fates in the environment. Knowledge of the function of amino acids of enzymes involved in enantioselective behaviors contributes to the understanding of the enantioselectivity of chiral pesticides. In this work, Aspergillus niger lipase (ANL, EC3.1.1.3) was chemically modified using bromoacetic acid (BrAc), 2,3-butanedione (BD), N-bromosuccinimide (NBS), and methanal. The enantioselectivity of the enzymatic hydrolysis of 2,4-dichlorprop-methyl (DCPPM) was investigated by chiral GC. The results have suggested that histidine, arginine, and tryptophan are essential for lipase activity and might be involved in the catalytic site of ANL. In addition, histidine and lysine play an important role in determining the observed enantioselective hydrolysis of chiral herbicide dichlorprop methyl. The molecular modeling study revealed that the essential hydrogen bonds formed between DCPPM and catalytic residues of ANL might be responsible for the enantioselectivity of DCPPM. The loss of enantioselectivity can also arise from the fact that the modification of the amino acids may cause changes in both the nature of the ANL enzyme conformation and the binding pattern of DCPPM. Our study provides basic information for the exploration of the enantioselective interaction mechanism of enzymes with chiral pesticides.

Technologies used for separating alkene from dry gas are reviewed,which include cryogenic method,absorption,hydrate separation,membrane separation and adsorption separation.The investment of cryogenic method and absorption is comparatively high.The purity of product obtained from hydrate separation process is low.Life of membrane used in membrane separation process is usually less than one year.The pressure swing adsorption considered as a clean and low cost technology is a promising technology applied in alkene separation from dry gas.

The adsorption equilibria of propylene and ethylene on 15 commercial activated carbons at 101.3 kPa and 313 K were investigated. The adsorption amount of propylene and ethylene on these adsorbents varied greatly from a minimum of 1.593 mmol.g(-1) for propylene and 1.430 mmol.g(-1) for ethylene to a maximum of 4.528 mmol.g(-1) for propylene and 3.100 mmol.g(-1) for ethylene. Characteristics of these activated carbon adsorbents such as the Brunauer-Emmett-Teller (BET) surface area, micropore area, external surface area, total pore volume, micropore volume, and average pore diameter were determined by a volumetric method. The adsorption amount of the two alkenes on these 15 carbon samples were correlated with their physical parameters. Both the BET surface area and micropore volume have an effect on their adsorption.

Characteristics of activated carbon adsorbents for the separation of propylene from dry gas are studied.Five kinds of activated carbon of different material are selected as candidates.Physical parameters such as BET surface area,pore volume,average pore diameter and micropore volume are measured.The adsorption amounts of activated carbons for ethylene and propylene,as well as the selectivities for propylene are obtained at a condition of 101.3 kPa and 40℃.Under above conditions the adsorption amount of activated carbon AC-1 for propylene can reach 3.552 mmol/g,which is the largest among all prepared catalysts.The adsorption amounts for propylene and ethylene are also measured under a range of partial pressure in binary mixed gas of ethylene and propylene.As a result AC-1 is chosen as the optimal one for the separation of propylene from dry gas.

利用手性气相色谱技术研究了硅藻土吸附作用对(RS)-2,4-二氯苯氧丙酸甲酯(2,4-DP)酶促水解对映体选择性的影响.实验结果表明,硅藻土吸附作用显著增强了酶促反应的对映体选择性(ER值由1.58增加到5.31).进一步研究表明,硅藻土对脂肪酶的吸附,引起酶构象变化,影响农药底物与酶结合的微环境,是酶促反应的对映体选择性增强的主要原因.吸附在硅藻土上的脂肪酶,与R-2,4-DP结合更为困难,反应速率下降;而S-2,4-DP接近酶反应中心更加容易,反应速率上升.此外,硅藻土吸附作用对农药底物的束缚引起处于自由状态的底物减少,也使酶促反应的对映体选择性略有增强.

The effect of kaolinite on the enzymatic chiral hydrolysis of methyl dichlorprop enantiomers ((R,S)-methyl-2-(2,4- dichlorophenoxy) propanoic acid, 2,4-DPM) was investigated using chiral gas chromatography. Compared with the control without kaolinite, the enantiomeric ratio (ER) increased from 1.35 to 8.33 and the residual ratio of 2,4-DPM decreased from 60.89% to 41.55% in the presence of kaolinite. Kaolinite likely had emotion influence on lipase activity and its enantioselectivity. Moreover, the amount of kaolinite added was also found to be a sensitive factor affecting the enantioselective hydrolysis of 2,4-DPM. Fourier transform infrared (FTIR) spectroscopy studies of the interaction of lipase with kaolinite provided insight into the molecular structure of the complex and offered explanation of the effects of kaolinite on enzymatic hydrolysis of 2,4-DPM. Spectra showed that the effect of kaolinite on the hydrolysis of 2,4-DPM was affected by adsorption of lipase on kaolinite and changes of adsorbed lipase conformation, which led to the modified enantioselectivity.

Environmental concerns have highlighted the need of cleaner technologies. A cleaner, convenient and selective technology has been developed for the preparation of 3-(4,6-dimethoxy-pyrimidin-2-yloxy)-2-methyl-phenol (DPMP) from 2-methyl-benzene-1,3-diol in water as solvent. The isolated yield of DPMP is up to 86% in good selectivity. The product structure was characterized by conventional methods,1H-NMR and MS. This technology belongs to the modern concept of environmentally friendly low wastes or non-wastes technology (LWNWT).

The binding of atrazine to catalase(CAT) in aqueous solution was studied with fluorospectroscopic method. The results show that atrazine has a strong ability to quench the CAT fluorescence mainly through a static quench procedure. The binding constant K and the number of binding site n were calculated according to the fluorescence quenching results. Based on the mechanism of energy transfer, the donor-acceptor distance of the herbicide and CAT was calculated as 0.159. It is inferred that the binding site of CAT to atrazine is Tyr-16.