Optimum Lipase Immobilized on Diamine-Grafted PVDF Membrane and Its Characterization

A facile and economic modification of polyvinylidene fluoride (PVDF) with an orientation of diamine is presented herein. The physical characterizations of native and diamine-grafted PVDF membranes are analyzed by three different techniques: the ninhydrin test, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The diamine-grafted PVDF is activated by glutaraldehyde for enzyme immobilization. The response surface methodology (RSM) is used to search the optimal immobilization conditions and to understand the significance of the factors affecting the responses of immobilized lipase. The optimal conditions for lipase immobilization are: a reaction time of 90 min, temperature of 35 degrees C, pH of 6, and an enzyme concentration of 7 mg/mL. An experiment performed under the optimum conditions obtains lipase activity of 60 U per g of membrane. A good agreement between the calculated and experimental values is thereby achieved

Optimal covalent immobilization of alpha-chymotrypsin on Fe3O4-chitosan nanoparticles

This study investigated the immobilization of alpha-chymotrypsin onto magnetic Fe3O4-chitosan (alpha-chymotrypsin-Fe3O4-CS) nanoparticles by covalent binding. The response surface methodology (RSM) with a 3-factor-3-level Box-Behnken experimental design was employed to evaluate the effects of the manipulated variables, including the immobilization time, temperature, and pH, on the enzyme activity. The results indicate that the immobilized temperature and pH significantly affected enzyme activity. In a ridge max analysis, the optimal condition for alpha-chymotrypsin immobilization included a reaction temperature of 21.7 degrees C, a pH of 7.6, and an incubation time of 1.1 h. The predicted and the experimental immobilized enzyme activities were 354 and 347 +/- 46.5 U/g-support, respectively, under the optimal condition. Besides, the synthesis reactions of the dipeptide derivative using the free and immobilized alpha-chymotrypsin were compared. The yields of the dipepticle derivative via the free or immobilized alpha-chymotrypsin catalyzed were almost the same. The alpha-chymotrypsin-Fe3O4-CS nanoparticles exhibited a good acid-resisting ability and the less reaction time was required for dipeptide synthesis. After twelve repeated uses in dipeptide synthesis, the immobilized alpha-chymotrypsin still retained over 60% of its original activity. The magnetic alpha-chymotrypsin-Fe3O4-CS nanoparticles can be easily recovered by magnetic field will have potential application in industry. (C) 2012 Elsevier By. All rights reserved

Optimized synthesis of lipase-catalyzed octyl caffeate by Novozym (R) 435

In this study, optimization of the enzymatic synthesis of octyl caffeate (OC), catalyzed by an immobilized lipase (Novozym (R) 435) from Candida antarctica was investigated. Novozym (R) 435 was used to catalyze the caffeic acid and octanol in an isooctane system. Response surface methodology (RSM) and 5-level-4factor central-composite rotatable design (CCRD) were employed to evaluate the effects of the synthesis parameters, such as reaction temperature (40-80 degrees C), reaction time (24-72h), substrate molar ratio of caffeic acid to octanol (1:20-1:100), and enzyme amounts (100-500 PLU) on the percentage conversion of OC by direct esterification. Reaction temperature and time had significant effects on the percent conversion. Based on ridge max analysis, the optimum conditions for synthesis were: reaction time of 55 h, reaction temperature of 75 degrees C, substrate molar ratio of 1:78, and enzyme amount of 317 PLU. The molar conversions of predicted and actual experimental values were 93.79% and 90.34 +/- 1.38%. respectively. (C) 2010 Elsevier B.V. All rights reserved

A continuous ultrasound-assisted packed-bed bioreactor for the lipase-catalyzed synthesis of caffeic acid phenethyl ester

BACKGROUND: The focus of this paper is the ultrasound-assisted synthesis of caffeic acid phenethyl ester (CAPE) from caffeic acid and phenyl ethanol in a continuous packed-bed bioreactor. Immobilized Novozym (R) 435 (from Candida antarctica) is used as the catalyst. A three-level-three-factor Box-Behnken design and a response surface methodology (RSM) are employed to evaluate the effects of temperature, flow rate, and ultrasonic power on the percentage molar conversion of CAPE. RESULTS: Based on ridge max analysis, it is concluded that the optimum condition for synthesis is reaction temperature 72.66 degrees C, flow rate 0.046 mL min(-1), and ultrasonic power 1.64 W cm(-2). The expected molar conversion value is 97.84%. An experiment performed under these optimal conditions resulted in a molar conversion of 92.11 +/- 0.75%. The enzyme in the bioreactor was found to be stable for at least 6 days. CONCLUSIONS: The lipase-catalyzed synthesis of CAPE by an ultrasound-assisted packed-bed bioreactor uses mild reaction conditions. Enzymatic synthesis of CAPE is suitable for use in the nutraceutical and food production industries. (C) 2011 Society of Chemical Industr

Optimized enzymatic synthesis of caffeic acid phenethyl ester by RSM

In this study, optimization of enzymatic synthesis of caffeic acid phenethyl ester (CAPE), catalyzed by immobilized lipase (Novozym (R) 435) from Candida antarctica was investigated. Novozym (R) 435 was used to catalyze caffeic acid and 2-phenylethanol in an isooctane system. Response surface methodology (RSM) and 5-level-4-factor central-composite rotatable design (CCRD) were employed to evaluate the effects of synthesis parameters, such as reaction temperature (30-70 degrees C), reaction time (24-72 hours), substrate molar ratio of caffeic acid to 2-phenylethanol (1:10-1:90) and enzyme amounts (100-500 PLU) on percentage conversion of CAPE by direct esterification. Reaction temperature and time had significant effects on percent conversion. On the basis of ridge max analysis, the optimum conditions for synthesis were: reaction time 59 hours, reaction temperature 69 degrees C, substrate molar ratio 1:72 and enzyme amount 351 PLU. The molar conversion of predicted values and actual experimental values were 91.86 +/- 5.35% and 91.65 +/- 0.66%, respectively