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ABSTRACT: The state of p-phenylphenol molecules in dioxane/water mixture, a commonly used reaction system for enzymatic polymerization of phenols and aromatic amines, was investigated by difference UV absorption spectroscopy and Fourier transform (FT) Raman spectroscopy. The aggregate of p-phenylphenols is found on the basis of the exciton peaks observed in difference UV absorption spectra. FT Raman spectroscopy demonstrates further that p-phenylphenol molecules aggregate together in “face to face” fashion. A simplified model is proposed for aggregation of p-phenylphenol molecules in dioxane/water mixture, which can elucidate the variation of the molecular weight of poly (p-phenylphenol) coupled in the reaction system. © 1995 John Wiley & Sons, Inc.
Journal of Polymer Science Part A Polymer Chemistry 03/2003; 33(14):2339 - 2345. · 3.92 Impact Factor
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ABSTRACT: In this article, the immobilization of prostaglandin synthetase on n-alkyl or aryl amino-agar beads by hydrophobic adsorption is reported. The effects of different hydrophobic groups in the agar beads, pH of buffer, concentration of salts on the adsorption of prostaglandin synthetase, and the properties of immobilized prostaglandin synthetase were also studied. The results showed that 20-35 mg of microsome containing PG synthetase (protein content 8-15 mg) could be adsorbed on each gram of n-dodecylamino-agar beads after suction drying the gel in the buffer of pH 5.5 (containing 0.5 mol/L KCl), 0.1 mol/L citric-phosphate at 4 degrees C. The remaining immobilized enzyme activity was over 80%. The optimum pH of immobilized PG synthetase is 8.0, similar to that of the native enzymes. The thermostability of immobilized PG synthetase in the buffer containing 0.5 mol/L KCl was increased. Immobilized PG synthetase was used as a catalyst of synthesis of prostaglandin E1. The preservation of activity after 10 working cycles was 86.2%.
Applied Biochemistry and Biotechnology 04/1996; 56(3):223-33. · 1.94 Impact Factor
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Annals of the New York Academy of Sciences 04/1995; 750:138-45. · 3.15 Impact Factor
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ABSTRACT: In this paper, we used Ca-alginate gel beads coated with polyetheneimine and glutaraldehyde to adsorb Expansum penicillium lipase. The immobilized lipase catalyzed esterification of 1-dodecanol with dodecanoic acid in benzene. The results show that when the concentration of Ca-alginate, polyetheneimine (PEI) and glutaraldehyde is 1%, 6% and 1%, respectively, the activity of the immobilized lipase and the amount of adsorbed protein are the highest. The immobilized lipase is better than the SDS-immobilized lipase. The activity of the immobilized lipase connected by glutaraldehyde is higher than the activity of that without glutaraldehyde. The initial rate of the immobilized lipase and lyophilized lipase powder is 5.9 x 10(2) nmol/min.mgpr and 2.8 x 10(1) nmol/min.mgpr, respectively. After the immobilized lipase catalyzed the esterification reaction at 37 degrees C for about 12 hours, 93.3% of 1-dodecanol was converted to ester, but for lyophilized lipase powder, only 17.5% converted. Based on all above results, we have presumed and explained the structure of this kind of immobilized lipase.
Biochemical and Biophysical Research Communications 05/1994; 200(1):83-8. · 2.48 Impact Factor
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Annals of the New York Academy of Sciences 12/1992; 672:60-5. · 3.15 Impact Factor
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ABSTRACT: The conditions for esterification and transesterification catalyzed by porcine pancreatic lipase in organic media were studied.
It was found that the enzyme reaction was dependent on the following factors: the pH at which the enzyme powder was prepared
from its solution, the polarity of organic media, the reaction temperature, the water content in reaction system, and the
substrate structures. Effects of the above factors on enzyme activity were discussed.
Applied Biochemistry and Biotechnology 12/1991; 32(1):7-13. · 1.94 Impact Factor
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ABSTRACT: In this paper, we report the reactions of esterification and transesterification catalyzed by the following lipase adducts
in organic solvents: (1) glass-adsorbed; (2) acetone precipitated on porous glass, kieselghur-adsorbed; (3) Al2O3-adsorbed; and (4) agar bead-adsorbed. The optimal water content varied for different forms of the enzymes. Under the most
favorable conditions, kieselguhr-adsorbed and agar bead-adsorbed lipases, which have higher catalytic activities in organic
solvents, are the best of all forms of lipases.
Applied Biochemistry and Biotechnology 12/1991; 32(1):1-6. · 1.94 Impact Factor
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ABSTRACT: Acetic anhydride, dextran and monomethoxypolyethylene glycol and different modification methods were used for modification of L-asparaginase to maintain enzyme activity and completely remove its antigenicity. The results showed that the macromolecular modifiers PEG and dextran were better than the small molecular modifier acetic anhydride. For maintenance of enzyme activity and removal of antigenicity modification in the presence of substrate was better than absence of substrate and activated PEG2 was better than activated PEG1. When PEG2-L-asparaginase was modified in the presence of substrate, its antigenicity was completely removed, while more than 30% of native enzyme activity were still retained.
Yao xue xue bao = Acta pharmaceutica Sinica 02/1990; 25(10):732-8.
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Annals of the New York Academy of Sciences 02/1990; 613:564-7. · 3.15 Impact Factor
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Annals of the New York Academy of Sciences 02/1990; 613:460-7. · 3.15 Impact Factor
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ABSTRACT: We believe that the activities of reactivated and reconstituted enzymes can be completely recovered if optimum conditions of reactivation and reconstitution are found.
Annals of the New York Academy of Sciences 02/1988; 542:75-8. · 3.15 Impact Factor
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Annals of the New York Academy of Sciences 02/1988; 542:79-82. · 3.15 Impact Factor
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CHEMICAL & PHARMACEUTICAL BULLETIN 11/1987; 35(10):4229-34. · 1.59 Impact Factor
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Yao xue xue bao = Acta pharmaceutica Sinica 03/1987; 22(2):126-9.
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Annals of the New York Academy of Sciences 02/1987; 501:88-91. · 3.15 Impact Factor
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Zhongguo yao li xue bao = Acta pharmacologica Sinica 01/1986; 6(4):276-8.
