Effects of water activity on Vmax and KM of lipase catalyzed transesterification in organic media

Bovara, Roberto; Carrea, Giacomo; Ottolina, Gianluca; Riva, Sergio

doi:10.1007/bf00131760

Cited by 71 publications

(36 citation statements)

References 24 publications

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“…[35,36] Graphs showing specific activity as a function of water activity (Figure 2 A and B) for the two lipases studied agree well with previous results on lipases. [35,37] Active site titrations of all the preparations resulted in graphs very similar to the activity graphs ( Figure 3 A and B).…”

Section: Water-activity Dependence Of Immobilised Lipasessupporting

confidence: 78%

Factors Governing the Activity of Lyophilised and Immobilised Lipase Preparations in Organic Solvents

2002

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Active site titration and activity measurements were performed in hexane on lyophilised lipase preparations containing different amounts of phosphate buffer and lipase immobilised on porous polypropylene. Lyophilisation of Thermomyces lanuginosus lipase with large quantities of phosphate salts (200 mM) increased the specific activity fourfold, and the number of rapidly titratable active sites increased to 50 % from the 13 % observed when smaller amounts of phosphate buffer were used (20 mM) during lyophilisation. The phosphate buffer worked as an immobilisation matrix for the lipase, and the increase in specific activity was at least partly due to decreased mass transfer limitations. When lipase was immobilised on porous polypropylene, the specific activity was 770 times higher than that of the best freeze-dried preparation. At optimal enzyme loading, 93 % of the enzyme molecules were titrated at a high rate; this indicates that this adsorption on a hydrophobic surface was a very efficient means of reducing mass transfer limitations and of immobilising the enzyme in its active conformation for use in organic solvents. The variation in specific activity with water activity was found to correlate very well with the variation in titratable active sites when lipases from Burkholderia cepacia and Thermomyces lanuginosus were immobilised on porous polypropylene. The catalytic activity per competent active site was thus constant over the whole range of water activities.

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Section: Water-activity Dependence Of Immobilised Lipasessupporting

confidence: 78%

Factors Governing the Activity of Lyophilised and Immobilised Lipase Preparations in Organic Solvents

2002

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“…Crude lipase mixtures suffer from stability problems in organic solvents and they contain contaminating side activities that have unexpected synthetic properties affecting the enzyme catalysis [9][10][11][12]. Soluble pure lipases cannot be used in synthesis as a result of low stability against high temperatures and organic solvents [9,14,15]. Cross-linked lipase crystals are considerably more stable in the presence of organic solvents than the soluble crude lipase preparations [9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 98%

Studies on crystallization and cross-linking of lipase for biocatalysis

Rajan

Abraham

2007

Bioprocess Biosyst Eng

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The development of robust biocatalysts with increased stability and activity is a major challenge to industry. A major breakthrough in this field was the development of cross-linked enzyme crystals with high specificity and stability. A method is described to produce micro crystals of CLEC lipase, which is thermostable and solvent stable. Lipase from Burkholderia cepacia was crystallized using ammonium sulfate and cross-linked with glutaraldehyde to produce catalytically active enzyme. The maximum yield of CLEC was obtained with 70% ammonium sulfate and cross-linked with 5% (v/v) glutaraldehyde. SEM studies showed small hexagonal-shaped crystals of 2-5 microm size. CLEC lipase had improved thermal and reuse stability. It is versatile, having good activity in both polar and nonpolar organic solvents. CLEC lipase was coated using beta cyclodextrin for improving the storage and reuse stability. CLEC was successfully used for esterification of Ibuprofen and synthesis of ethyl butyrate.

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“…Protein concentration was estimated as described by Lowry using bovine serum albumin as a standard [24]. The 4-nitrophenyl acetate formed in each of the combinations of the reactants was quantiWed by using alkalimetric method of titrating unreacted acid with 0.1 N NaOH using phenolphthalein as an indicator [5]. The conversion (%) in ester synthesis was based on acid consumed.…”

Section: Enzyme Immobilization and Esteriwcationmentioning

confidence: 99%

Synthesis of 4-nitrophenyl acetate using molecular sieve-immobilized lipase from Bacillus coagulans

Raghuvanshi

Gupta

2008

J Ind Microbiol Biotechnol

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Extracellular lipase from Bacillus coagulans BTS-3 was immobilized on (3 A x 1.5 mm) molecular sieve. The molecular sieve showed approximately 68.48% binding efficiency for lipase (specific activity 55 IU mg(-1)). The immobilized enzyme achieved approx 90% conversion of acetic acid and 4-nitrophenol (100 mM each) into 4-nitrophenyl acetate in n-heptane at 65 degrees C in 3 h. When alkane of C-chain length other than n-heptane was used as the organic solvent, the conversion of 4-nitrophenol and acetic acid was found to decrease. About 88.6% conversion of the reactants into ester was achieved when reactants were used at molar ratio of 1:1. The immobilized lipase brought about conversion of approximately 58% for esterification of 4-nitrophenol and acetic acid into 4-nitrophenyl acetate at a temperature of 65 degrees C after reuse for 5 cycles.

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Effects of water activity on Vmax and KM of lipase catalyzed transesterification in organic media

Cited by 71 publications

References 24 publications

Factors Governing the Activity of Lyophilised and Immobilised Lipase Preparations in Organic Solvents

Factors Governing the Activity of Lyophilised and Immobilised Lipase Preparations in Organic Solvents

Studies on crystallization and cross-linking of lipase for biocatalysis

Synthesis of 4-nitrophenyl acetate using molecular sieve-immobilized lipase from Bacillus coagulans

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