3 94.72 84.66 84.Eq. (two) which indicated a superb agreement involving actual and predicted responses.Mutual effect of parameters and attaining optimum conditionThe response surface and contour plots in Figure 11 show the primary, interaction, and quadratic effect of two independent variables on conversion price. Figure 11(a, b) shows the impact of enzyme load (X1) and temperature (X3) around the conversion price of isoascorbyl palmitate at the molar ratio kept at a continual level. It was obvious that the conversion price of isoascorbyl palmitate was sensitive even when enzyme load was subject to small alteration. An increase within the conversion rate might be significantly enhanced using the improve of enzyme load and temperate. Figure 11(c, d) shows the impact of enzyme load (X1) and molar ratio (X2) on the conversion rate of isoascorbyl palmitate in the temperature kept at a constant level. From the figures, we can see that a higher conversion price will obtained utilizing a high molar ratio of D-isoascorbic to palmitic acid. Figure 11 (e, f) shows the interaction amongst molar ratio (X2) and temperature (X3) on the conversion price of isoascorbyl palmitate at the enzyme load kept at a continuous level. Because it is shown, the conversion price elevated slightly with escalating temperature from 40 to 60 in the selection of molar ratio. The optimal circumstances for D- isoascorbyl palmitate synthesis was obtained by utilizing the Point prediction function of application Design-Expert 7.1.1 to calculateSun et al. Chemistry Central Journal 2013, 7:114 http://journal.chemistrycentral/content/7/1/Page ten ofFigure 10 Plot of predicted and observed conversion price ( ) of D-isoascorbyl palmitate.maximum degree of conversion rate. The maximum conversion rate of D- isoascorbyl palmitate was 96.98 beneath the reaction circumstances as follows: enzyme load of 20 (w/w), reaction temperature of 53 and D- isoascorbic-to-palmitic acid molar ratio of 1:4.Validation from the modelThe availability from the regression model (Eq. (two)) with the conversion price of isoascorbyl palmitate was tested applying the calculated optimal condition, viz. acetone 20 mL, 40 g/L of molecular sieves content, 200 rpm speed, 20 enzyme load, D- isoascorbic-to-palmitic acid molar ratio of 1:four, temperature of 53o for 24-h through the course of optimization experiments.5-Fluoro-1H-1,2,4-triazole web The mean worth with the mycelial biomass was 95.32 ?0.17 , which agreed using the predicted worth (96.98 ) effectively that indicated the higher validity and adequacy on the model.Ltd (Shenzhen, China). The properties of all lipases are shown in Table 1. 2-Methyl-2-butanol, n-hexane, ethanol, chloroform, petroleum ether, acetone and acetic ether have been analytical reagent grade purchased from Sinopharm Chemical Reagent Co.Price of 2-Bromo-6-(difluoromethoxy)pyridine , Ltd (Shanghai, China).PMID:23329319 HPLC-grade methanol was purchased from Tedia, USA. All reagents had been dehydrated by molecular sieve 4 ?(Shanghai planet molecular sieve Co., Ltd., Shanghai, China) for no less than 24 h and filtered using a membrane filter (0.45 m) before use as a reaction medium.Procedure for lipase-catalysed esterificationExperimentalMaterialsD-isoascorbic acid (purity 99 ) was supplied from Parchn Sodium Isovitamin C Co., Ltd (Dexing, Jiangxi, China). Palmitic acid (purity 99.5 ) was obtained from Sinopharm Chemical Reagent Co., Ltd (Shanghai, China). Novozym 435 was purchased from Novo Nordisk Co., Ltd (Beijing, China). Lipozyme TLIM, a lipase from Thermomyces lanuginosus immobilized on silica granulation and Lipozyme RMIM, a lipase from Rhizomucor.