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Publications (4)8.08 Total impact

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    ABSTRACT: Typoselectivity of crude CBD-T1 lipase (Geobacillus sp. T1 lipase fused with a cellulose binding domain) was investigated. Multi-competitive reaction mixtures including a set of n-chain fatty acids (C8:0, C10:0, C12:0, C14:0, C18:1 n-9, C18:2 n-6 and C18:3 n-3) and tripalmitin-enriched triacylglycerols were studied in hexane. The crude CBD-T1 lipase discriminated strongly against C18:1 n-9 [competitive factor (α) = 0.23] and showed the highest preference for C8:0 (α = 1). Utilizing the catalytic properties of crude CBD-T1 lipase, acidolysis of soybean oil with C8:0 was selected as a model reaction to investigate the ability of the lipase to produce MLM-type (medium-long-medium) structured lipids. Several reaction parameters (added water amount, reaction temperature, substrate molar ratio and reaction time) examined for incorporating C8:0 into soybean oil, the optimum conditions were: 1:3 (soybean oil/C8:0) of molar ratio, 3 mL of hexane, 50 °C of temperature, 48 h of reaction time, 20 % of crude CBD-T1 lipase (w/w total substrates), and 7.5 % of water (w/w enzyme). Under these conditions, the incorporation of C8:0 was 29.6 mol%. The results suggest that crude CBD-T1 lipase, which showed different fatty acid specificity profiles, is a potential biocatalyst for the modification of fats and oils.
    Journal of Oil & Fat Industries 01/2014; 91(1). · 1.59 Impact Factor
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    ABSTRACT: Human milk fat substitutes (HMFS) were prepared by enzymatic synthesis combined with physical blending methods. As the main constituents in HMFS, 1,3-dioleoyl-2-palmitoylglycerol-rich TAGs (OPO-rich TAGs) were synthesized in one step by Lipozyme RM IM-catalyzed acidolysis of 34L-leaf lard and then purified by molecular distillation. The results showed that OPO-rich TAGs with purity of 91.39wt% were obtained at evaporation temperature of 180°C and a pressure of 6.7–7.5 Pa. Furthermore, a mathematical model was established for formulating HMFS by blending OPO-rich TAGs product with the selected vegetable oils. Under the blending ratio of 0.6700:0.1638:0.1627:0.0035:0.0000 (OPO-rich TAGs product/coconut oil/soybean oil/flaxseed oil/sunflower seed oil), the HMFS had fatty acids levels similar to those of human milk fat (HMF), and kept a high proportion (about 70%) of C16:0 at the sn-2 position. Based on the fatty acid composition and distribution of HMF and “deducting score” principle, the similarity of HMFS to HMF was assessed by the related model, and the score for the similarity of HMFS to HMF was 85.54 points, indicating that this HMFS can be used as a fat substitute in infant formula. This study can provide valuable information on preparing HMFS and will be helpful for the infant formula industry.Practical applications: The information on the whole process of the production of HMFS, including one-step enzymatic synthesis, purification, quality evaluation and physical blending, is important for the development of infant formula with high quality. The enzymatic synthesis combined with physical blending methods enable a high similarity of HMFS to human milk fat and the HMFS can be used a potential fat substitute in infant formula.
    European Journal of Lipid Science and Technology 12/2013; · 2.27 Impact Factor
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    ABSTRACT: T1 lipase has received considerable attention due to its thermostability. Fatty acid specificity of T1 lipase (crude and purified) was investigated, and its potential in the synthesis of acylglycerols was also evaluated. Fatty acid specificity of T1 lipase (crude and purified) was investigated in the esterification of fatty acids (C6:0 to C18:3), suggesting that crude and purified T1 lipase had the lowest preference for C18:0 [specificity constant (1/α) = 0.08] followed by C18:1 (1/α = 0.12) and showed the highest preference for C8:0 (1/α = 1). A structural model was constructed to briefly explore interactions between the lipase and its substrate. Furthermore, crude T1 lipase-catalysed synthesis of diacylglycerols (DAGs) and monoacylglycerols (MAGs) by esterification of glycerol with C18:1 was studied for evaluating its potential in acylglycerols synthesis. The optimal conditions were glycerol/oleic acid molar ratio 5:1, the lipase concentration 9.7 U g(-1) of substrates, water content 50 g kg(-1) of substrates and temperature 50 °C, which yielded 42.25% DAGs, 26.34% MAGs and 9.18% triacylglycerols at 2 h. DAGs and MAGs were synthesised in good yields although C18:1 (a much poorer substrate) was used. Our work demonstrates that T1 lipase, which was discovered to show 1,3-regio-selectivity, is a promising biocatalyst for lipids modification. © 2013 Society of Chemical Industry.
    Journal of the Science of Food and Agriculture 11/2013; · 1.76 Impact Factor
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    ABSTRACT: A novel lipase gene lip5 from the yeast Candida albicans was cloned and sequenced. Alignment of amino acid sequences revealed that 86-34% identity exists with lipases from other Candida species. The lipase and its mutants were expressed in the yeast Pichia pastoris, where alternative codon usage caused the mistranslation of 154-Ser and 293-Ser as leucine. 154-Ser to leucine resulted in loss of expression of Lip5, and 293-Ser to leucine caused a marked reduction in the lipase activity. Lip5-DM, which has double mutations that revert 154 and 293 to serine residues, showed good lipase activity, and was overexpressed and purified by (NH(4))(2)SO(4) precipitation and ion-exchange chromatography. The pure Lip5-DM was stable at low temperatures ranging from 15-35 °C and pH 5-9, with the optimal conditions being 15-25 °C and pH 5-6. The activation energy of recombinant lipase was 8.5 Kcal/mol between 5 and 25 °C, suggesting that Lip5-DM was a cold-active lipase. Its activity was found to increase in the presence of Zn(2+), but it was strongly inhibited by Fe(2+), Fe(3+), Hg(2+) and some surfactants. In addition, the Lip5-DM could not tolerate water-miscible organic solvents. Lip5-DM exhibited a preference for the short-and medium-chain length p-nitrophenyl (C4 and C8 acyl group) esters rather than the long chain length p-nitrophenyl esters (C12, C16 and C18 acyl group) with highest activity observed with the C8 derivatives. The recombinant enzyme displayed activity toward triacylglycerols, such as olive oil and safflower oil.
    International Journal of Molecular Sciences 01/2011; 12(6):3950-65. · 2.46 Impact Factor