Reaction products of 2,4,6-tris(4-phenyl-phenoxy)-1,3,5-triazine derived from 4-phenylphenol cyanate ester and phenyl glycidyl ether were analyzed. In addition to an isocyanurate compound and an oxazolidone compound w...Reaction products of 2,4,6-tris(4-phenyl-phenoxy)-1,3,5-triazine derived from 4-phenylphenol cyanate ester and phenyl glycidyl ether were analyzed. In addition to an isocyanurate compound and an oxazolidone compound which were well known as reaction products of cyanate esters and epoxy resins, compounds with hybrid ring structure of cyanurate/isocyanurate were determined. Gibbs free energies of the compound having hybrid ring structure of cyanurate/isocyanurate with two isocyanurate moiety were found to be lower than that of the compound with cyanurate ring structure through calculations. Calculation data supported the existence of hybrid ring structure of cy-anurate/isocyanurate. It was revealed that isomerization from cyanurate to isocyanurate occurs via hybrid ring structure of cyanurate/isocyanurate in the reaction of aryl cyanurate and epoxy.展开更多
Theoretical analysis corresponding to the diffusion and reaction kinetics in a chemical reaction between carbon dioxide and phenyl glycidyl ether solution is presented. Analytical expressions pertaining to the concent...Theoretical analysis corresponding to the diffusion and reaction kinetics in a chemical reaction between carbon dioxide and phenyl glycidyl ether solution is presented. Analytical expressions pertaining to the concentration of carbon dioxide (CO2), phenyl glycidyl ether solution (PGE) and flux are obtained in terms of reaction rate constants. In this paper, a powerful analytical method, called the Adomian decomposition method (ADM) is used to obtain approximate analytical solutions for nonlinear differential equations. Furthermore, in this work the numerical simulation of the problem is also reported using Scilab/Matlab program. An agreement between analytical and numerical results is noted.展开更多
Hydrophobic interaction chromatography(HIC)as an indispensable method for protein purification has attracted considerable attentions of researchers as well as biopharmaceutical industries.However,the low binding capac...Hydrophobic interaction chromatography(HIC)as an indispensable method for protein purification has attracted considerable attentions of researchers as well as biopharmaceutical industries.However,the low binding capacity and slow adsorption rate of the currently available HIC media lead to a little supply and high price of the highly purified proteins.Herein,nanofibrous membranes with hydrophobic binding sites were developed for HIC by directly coupling phenyl glycidyl ether on the hydrolyzed cellulose acetate nanofiber membrane(cellulose-phenyl NFM).Scanning electron microscope(SEM),water contact angle(WCA),Fourier transform infrared(FTIR),thermogravimetric analysis(TGA),Brunauer-Emmett-Teller(BET)surface area analysis and capillary flow porometer(CFP)were applied to evaluate the physically and chemically structural transformation.The obtained cellulose-phenyl NFMs showed a proper hydrophilcity(WCA=37°),a relatively high BET surface area(3.6 times the surface area of commercial fibrous membranes),and tortuous-channel structure with through-hole size in the range of 0.25-1.2μm,which led to a little non-specificity adsorption,high bovine serum albumin adsorption capacity of 118 mg g^(−1),fast adsorption process within 12 h,good long-term stability and reusability.Moreover,compared with traditional modification methods which always include activation and graft two steps,direct coupling method is more efficient for HIC media fabrication.Therefore,cellulose-phenyl NFMs with outstanding protein adsorption performance could be a kind of promising candidate for HIC.展开更多
The epoxide hydrolase gene(SpEH) from Sphingomonas sp. HXN-200 was synthesized and expressed in robust Escherichia coli cells that had a dual protection system. The enantioselectivity(E-value) of the recombinant SpEH ...The epoxide hydrolase gene(SpEH) from Sphingomonas sp. HXN-200 was synthesized and expressed in robust Escherichia coli cells that had a dual protection system. The enantioselectivity(E-value) of the recombinant SpEH was 7.7 and the yield of the remaining(R)-PGE was 24.3% for the hydrolysis of racemic phenyl glycidyl ether(rac-PGE). To improve the catalytic properties of SpEH, the site-directed mutagenesis was carried out based on homology modeling, sequence alignment and molecular docking. Six residues(V195, V196, F218,N226, Q312, and M332) near the active site were mutated to hydrophobic amino acids and the positive mutations were selected for combinatorial mutation. The optimal mutant SpEH^(V196A/N226A/M332A) had an enhanced E-value of 21.2 and a specific activity of 4.57 U·mg^-1-wet cells, which were 2.8-, and 2.3-fold higher than those of wild-type SpEH. The optimal temperature and p H for purified Sp EHV196 A/N226 A/M332 Ato catalyze the hydrolysis of rac-PGE were 25 ℃ and 7.0 with 200 U·mg^-1. The enantioselectivity and yield of the remaining(R)-PGE of E. coliSpEH^(V196A/N226A/M332A)increased from 7.7 to 21.2 and 24.3% to 40.9%, respectively. The molecular docking and kinetic parameter analyses showed that SpEH^(V196A/N226A/M332A) has a greater affinity toward(S)-PGE than(R)-PGE, and that it was more difficult for the O-atom of ASP170 to achieve the nucleophilic attack on the Cα of(R)-PGE, resulting in its improved enantioselectivity.展开更多
文摘Reaction products of 2,4,6-tris(4-phenyl-phenoxy)-1,3,5-triazine derived from 4-phenylphenol cyanate ester and phenyl glycidyl ether were analyzed. In addition to an isocyanurate compound and an oxazolidone compound which were well known as reaction products of cyanate esters and epoxy resins, compounds with hybrid ring structure of cyanurate/isocyanurate were determined. Gibbs free energies of the compound having hybrid ring structure of cyanurate/isocyanurate with two isocyanurate moiety were found to be lower than that of the compound with cyanurate ring structure through calculations. Calculation data supported the existence of hybrid ring structure of cy-anurate/isocyanurate. It was revealed that isomerization from cyanurate to isocyanurate occurs via hybrid ring structure of cyanurate/isocyanurate in the reaction of aryl cyanurate and epoxy.
文摘Theoretical analysis corresponding to the diffusion and reaction kinetics in a chemical reaction between carbon dioxide and phenyl glycidyl ether solution is presented. Analytical expressions pertaining to the concentration of carbon dioxide (CO2), phenyl glycidyl ether solution (PGE) and flux are obtained in terms of reaction rate constants. In this paper, a powerful analytical method, called the Adomian decomposition method (ADM) is used to obtain approximate analytical solutions for nonlinear differential equations. Furthermore, in this work the numerical simulation of the problem is also reported using Scilab/Matlab program. An agreement between analytical and numerical results is noted.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.51673037,51873029,and 81771338)the Science and Technology Commission of Shanghai Municipality(Grant No.18511109500).
文摘Hydrophobic interaction chromatography(HIC)as an indispensable method for protein purification has attracted considerable attentions of researchers as well as biopharmaceutical industries.However,the low binding capacity and slow adsorption rate of the currently available HIC media lead to a little supply and high price of the highly purified proteins.Herein,nanofibrous membranes with hydrophobic binding sites were developed for HIC by directly coupling phenyl glycidyl ether on the hydrolyzed cellulose acetate nanofiber membrane(cellulose-phenyl NFM).Scanning electron microscope(SEM),water contact angle(WCA),Fourier transform infrared(FTIR),thermogravimetric analysis(TGA),Brunauer-Emmett-Teller(BET)surface area analysis and capillary flow porometer(CFP)were applied to evaluate the physically and chemically structural transformation.The obtained cellulose-phenyl NFMs showed a proper hydrophilcity(WCA=37°),a relatively high BET surface area(3.6 times the surface area of commercial fibrous membranes),and tortuous-channel structure with through-hole size in the range of 0.25-1.2μm,which led to a little non-specificity adsorption,high bovine serum albumin adsorption capacity of 118 mg g^(−1),fast adsorption process within 12 h,good long-term stability and reusability.Moreover,compared with traditional modification methods which always include activation and graft two steps,direct coupling method is more efficient for HIC media fabrication.Therefore,cellulose-phenyl NFMs with outstanding protein adsorption performance could be a kind of promising candidate for HIC.
基金the National Natural Science Foundation of China(21676104,21878105,21908070)the National Key Research and Development Program of China(2018YFC1603400,2018YFC1602100)+3 种基金the Key Research and Development Program of Guangdong Province(2019B020213001)the Science and Technology Program of Guangzhou(201904010360)the Fundamental Research Funds for the Central Universities(2019PY15,2019MS100)the China Postdoctoral Science Foundation(BX20180102)for partially funding this work。
文摘The epoxide hydrolase gene(SpEH) from Sphingomonas sp. HXN-200 was synthesized and expressed in robust Escherichia coli cells that had a dual protection system. The enantioselectivity(E-value) of the recombinant SpEH was 7.7 and the yield of the remaining(R)-PGE was 24.3% for the hydrolysis of racemic phenyl glycidyl ether(rac-PGE). To improve the catalytic properties of SpEH, the site-directed mutagenesis was carried out based on homology modeling, sequence alignment and molecular docking. Six residues(V195, V196, F218,N226, Q312, and M332) near the active site were mutated to hydrophobic amino acids and the positive mutations were selected for combinatorial mutation. The optimal mutant SpEH^(V196A/N226A/M332A) had an enhanced E-value of 21.2 and a specific activity of 4.57 U·mg^-1-wet cells, which were 2.8-, and 2.3-fold higher than those of wild-type SpEH. The optimal temperature and p H for purified Sp EHV196 A/N226 A/M332 Ato catalyze the hydrolysis of rac-PGE were 25 ℃ and 7.0 with 200 U·mg^-1. The enantioselectivity and yield of the remaining(R)-PGE of E. coliSpEH^(V196A/N226A/M332A)increased from 7.7 to 21.2 and 24.3% to 40.9%, respectively. The molecular docking and kinetic parameter analyses showed that SpEH^(V196A/N226A/M332A) has a greater affinity toward(S)-PGE than(R)-PGE, and that it was more difficult for the O-atom of ASP170 to achieve the nucleophilic attack on the Cα of(R)-PGE, resulting in its improved enantioselectivity.
