Displaying publications 81 - 100 of 195 in total

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  1. Immobilized Candida antarctica lipase B: Hydration, stripping off and application in ring opening polyester synthesis
    Idris A, Bukhari A
    Biotechnol Adv, 2012 May-Jun;30(3):550-63.
    PMID: 22041165 DOI: 10.1016/j.biotechadv.2011.10.002
    This work reviews the stripping off, role of water molecules in activity, and flexibility of immobilized Candida antarctica lipase B (CALB). Employment of CALB in ring opening polyester synthesis emphasizing on a polylactide is discussed in detail. Execution of enzymes in place of inorganic catalysts is the most green alternative for sustainable and environment friendly synthesis of products on an industrial scale. Robust immobilization and consequently performance of enzyme is the essential objective of enzyme application in industry. Water bound to the surface of an enzyme (contact class of water molecules) is inevitable for enzyme performance; it controls enzyme dynamics via flexibility changes and has intensive influence on enzyme activity. The value of pH during immobilization of CALB plays a critical role in fixing the active conformation of an enzyme. Comprehensive selection of support and protocol can develop a robust immobilized enzyme thus enhancing its performance. Organic solvents with a log P value higher than four are more suitable for enzymatic catalysis as these solvents tend to strip away very little of the enzyme surface bound water molecules. Alternatively ionic liquid can work as a more promising reaction media. Covalent immobilization is an exclusively reliable technique to circumvent the leaching of enzymes and to enhance stability. Activated polystyrene nanoparticles can prove to be a practical and economical support for chemical immobilization of CALB. In order to reduce the E-factor for the synthesis of biodegradable polymers; enzymatic ring opening polyester synthesis (eROPS) of cyclic monomers is a more sensible route for polyester synthesis. Synergies obtained from ionic liquids and immobilized enzyme can be much effective eROPS.
    Matched MeSH terms: Enzymes, Immobilized/chemistry*
  2. Fulltext A biosensor for urea from succinimide-modified acrylic microspheres based on reflectance transduction
    Ulianas A, Heng LY, Ahmad M
    Sensors (Basel), 2011;11(9):8323-38.
    PMID: 22164078 DOI: 10.3390/s110908323
    New acrylic microspheres were synthesised by photopolymerisation where the succinimide functional group was incorporated during the microsphere preparation. An optical biosensor for urea based on reflectance transduction with a large linear response range to urea was successfully developed using this material. The biosensor utilized succinimide-modified acrylic microspheres immobilized with a Nile blue chromoionophore (ETH 5294) for optical detection and urease enzyme was immobilized on the surface of the microspheres via the succinimide groups. No leaching of the enzyme or chromoionophore was observed. Hydrolysis of the urea by urease changes the pH and leads to a color change of the immobilized chromoionophore. When the color change was monitored by reflectance spectrophotometry, the linear response range of the biosensor to urea was from 0.01 to 1,000 mM (R2 = 0.97) with a limit of detection of 9.97 μM. The biosensor response showed good reproducibility (relative standard deviation = 1.43%, n = 5) with no interference by major cations such as Na+, K+, NH4+ and Mg2+. The use of reflectance as a transduction method led to a large linear response range that is better than that of many urea biosensors based on other optical transduction methods.
    Matched MeSH terms: Enzymes, Immobilized/chemistry
  3. Enzymatic synthesis of farnesyl laurate in organic solvent: initial water activity, kinetics mechanism, optimization of continuous operation using packed bed reactor and mass transfer studies
    Rahman NK, Kamaruddin AH, Uzir MH
    Bioprocess Biosyst Eng, 2011 Aug;34(6):687-99.
    PMID: 21327986 DOI: 10.1007/s00449-011-0518-y
    The influence of water activity and water content was investigated with farnesyl laurate synthesis catalyzed by Lipozyme RM IM. Lipozyme RM IM activity depended strongly on initial water activity value. The best results were achieved for a reaction medium with an initial water activity of 0.11 since it gives the best conversion value of 96.80%. The rate constants obtained in the kinetics study using Ping-Pong-Bi-Bi and Ordered-Bi-Bi mechanisms with dead-end complex inhibition of lauric acid were compared. The corresponding parameters were found to obey the Ordered-Bi-Bi mechanism with dead-end complex inhibition of lauric acid. Kinetic parameters were calculated based on this model as follows: V (max) = 5.80 mmol l(-1) min(-1) g enzyme(-1), K (m,A) = 0.70 mmol l(-1) g enzyme(-1), K (m,B) = 115.48 mmol l(-1) g enzyme(-1), K (i) = 11.25 mmol l(-1) g enzyme(-1). The optimum conditions for the esterification of farnesol with lauric acid in a continuous packed bed reactor were found as the following: 18.18 cm packed bed height and 0.9 ml/min substrate flow rate. The optimum molar conversion of lauric acid to farnesyl laurate was 98.07 ± 0.82%. The effect of mass transfer in the packed bed reactor has also been studied using two models for cases of reaction limited and mass transfer limited. A very good agreement between the mass transfer limited model and the experimental data obtained indicating that the esterification in a packed bed reactor was mass transfer limited.
    Matched MeSH terms: Enzymes, Immobilized/chemistry
  4. Chemometric analysis of lipase-catalyzed synthesis of xylitol esters in a solvent-free system
    Adnani A, Basri M, Chaibakhsh N, Ahangar HA, Salleh AB, Rahman RN, et al.
    Carbohydr Res, 2011 Mar 1;346(4):472-9.
    PMID: 21276966 DOI: 10.1016/j.carres.2010.12.023
    Immobilized Candida antarctica lipase B-catalyzed esterification of xylitol and two fatty acids (capric and caproic acid) were studied in a solvent-free system. The Taguchi orthogonal array method based on three-level-four-variables with nine experiments was applied for the analysis and optimization of the reaction parameters including time, substrate molar ratio, amount of enzyme, and amount of molecular sieve. The obtained conversion was higher in the esterification of xylitol and capric acid with longer chain length. The optimum conditions derived via the Taguchi approach for the synthesis of xylitol caprate and xylitol caproate were reaction time, 29 and 18h; substrate molar ratio, 0.3 and 1.0; enzyme amount, 0.20 and 0.05g, and molecular sieve amount of 0.03g, respectively. The good correlation between the predicted conversions (74.18% and 61.23%) and the actual values (74.05% and 60.5%) shows that the model derived from the Taguchi orthogonal array can be used for optimization and better understanding of the effect of reaction parameters on the enzymatic synthesis of xylitol esters in a solvent-free system.
    Matched MeSH terms: Enzymes, Immobilized/chemistry*
  5. Fulltext Estimation of 16S rRNA gene copy number in several probiotic Lactobacillus strains isolated from the gastrointestinal tract of chicken
    Lee CM, Sieo CC, Abdullah N, Ho YW
    FEMS Microbiol Lett, 2008 Oct;287(1):136-41.
    PMID: 18707622 DOI: 10.1111/j.1574-6968.2008.01305.x
    The copy numbers of 16S rRNA genes in 12 probiotic Lactobacillus strains of poultry origin were analyzed. Genomic DNA of the strains was digested with restriction endonucleases that do not cut within the 16S rRNA gene of the strains. This was followed by Southern hybridization with a biotinylated probe complementary to the 16S rRNA gene. The copy number of the 16S rRNA gene within a Lactobacillus species was found to be conserved. From the hybridization results, Lactobacillus salivarius I 24 was estimated to have seven copies of the 16S rRNA gene, Lactobacillus panis C 17 to have five copies and Lactobacillus gallinarum strains I 16 and I 26 four copies. The 16S rRNA gene copy numbers of L. gallinarum and L. panis reported in the present study are the first record. Lactobacillus brevis strains I 12, I 23, I 25, I 211, I 218 and Lactobacillus reuteri strains C 1, C 10, C 16 were estimated to have at least four copies of the 16S rRNA gene. In addition, distinct rRNA restriction patterns which could discriminate the strains of L. reuteri and L. gallinarum were also detected. Information on 16S rRNA gene copy number is important for physiological, evolutionary and population studies of the bacteria.
    Matched MeSH terms: DNA Restriction Enzymes/metabolism
  6. Production of biodiesel using immobilized lipase--a critical review
    Jegannathan KR, Abang S, Poncelet D, Chan ES, Ravindra P
    Crit Rev Biotechnol, 2008;28(4):253-64.
    PMID: 19051104 DOI: 10.1080/07388550802428392
    Increase in volume of biodiesel production in the world scenario proves that biodiesel is accepted as an alternative to conventional fuel. Production of biodiesel using alkaline catalyst has been commercially implemented due to its high conversion and low production time. For the product and process development of biodiesel, enzymatic transesterification has been suggested to produce a high purity product with an economic, environment friendly process at mild reaction conditions. The enzyme cost being the main hurdle can be overcome by immobilization. Immobilized enzyme, which has been successfully used in various fields over the soluble counterpart, could be employed in biodiesel production with the aim of reducing the production cost by reusing the enzyme. This review attempts to provide an updated compilation of the studies reported on biodiesel production by using lipase immobilized through various techniques and the parameters, which affect their functionality.
    Matched MeSH terms: Enzymes, Immobilized*
  7. Chemoenzymatic and microbial dynamic kinetic resolutions
    Kamaruddin AH, Uzir MH, Aboul-Enein HY, Halim HN
    Chirality, 2009 Apr;21(4):449-67.
    PMID: 18655180 DOI: 10.1002/chir.20619
    This review tracks a decade of dynamic kinetic resolution developments with a biocatalytic inclination using enzymatic/microbial means for the resolution part followed by the racemization reactions either by means of enzymatic or chemocatalyst. These fast developments are due to the ability of the biocatalysts to significantly reduce the number of synthetic steps which are common for conventional synthesis. Future developments in novel reactions and products of dynamic kinetic resolutions should consider factors that are needed to be extracted at the early synthetic stage to avoid inhibition at scale-up stage have been highlighted.
    Matched MeSH terms: Enzymes/chemistry
  8. Enzymatic deinking of laser printed office waste papers: some governing parameters on deinking efficiency
    Lee CK, Darah I, Ibrahim CO
    Bioresour Technol, 2007 May;98(8):1684-9.
    PMID: 17137782
    The protocol for the enzymatic deinking of laser printed waste papers on a laboratory scale using cellulase (C) and hemicellulase (H) of Aspergillus niger (Amano) was developed as an effective method for paper recycling. A maximum deinking efficiency of almost 73% by the enzyme combination of C:H was obtained using the deinking conditions of pulping consistency of 1.0% (w/v) with the pulping time of 1.0min, temperature of 50 degrees C, pH=3.5, agitation rate of 60rpm, pulp concentration of 4% (w/v), concentration of each enzyme of 2.5U/g air dried pulp and the enzyme ratio of 1:1. The deinking efficiency was further enhanced to 95% using the optimized flotation system consisting of pH=6.0, Tween 80 of concentration 0.5% (w/w), working air flow rate of 10.0L/min and temperature of 45 degrees C. The deinked papers were found to exhibit properties comparable to the commercial papers suggesting the effectiveness of the enzymatic process developed.
    Matched MeSH terms: Enzymes/metabolism*
  9. Lipase catalyzed ultrasonic synthesis of poly-4-hydroxybutyrate-co-6-hydroxyhexanoate
    Gumel AM, Annuar MS, Chisti Y
    Ultrason Sonochem, 2013 May;20(3):937-47.
    PMID: 23231942 DOI: 10.1016/j.ultsonch.2012.09.015
    Four different lipases were compared for ultrasound-mediated synthesis of the biodegradable copolymer poly-4-hydroxybutyrate-co-6-hydroxyhexanoate. The copolymerization was carried out in chloroform. Of the enzymes tested, Novozym 435 exhibited the highest copolymerization rate, in fact the reaction rate was observed to increase with about 26-fold from 30 to 50°C (7.9×10(-3)Ms(-1)), sonic power intensity of 2.6×10(3)Wm(-2) and dissipated energy of 130.4Jml(-1). Copolymerization rates with the Candida antarctica lipase A, Candida rugosa lipase, and Lecitase Ultra™ were lower at 2.4×10(-4), 1.3×10(-4) and 3.5×10(-4)Ms(-1), respectively. The catalytic efficiency depended on the enzyme. The efficiency ranged from 4.15×10(-3)s(-1)M(-1) for Novozym 435-1.48×10(-3)s(-1)M(-1) for C. rugosa lipase. Depending on the enzyme and sonication intensity, the monomer conversion ranged from 8.2% to 48.5%. The sonication power, time and temperature were found to affect the rate of copolymerization. Increasing sonication power intensity from 1.9×10(3) to 4.5×10(3)Wm(-2) resulted in an increased in acoustic pressure (P(a)) from 3.7×10(8) to 5.7×10(8)Nm(-2) almost 2.4-3.7 times greater than the acoustic pressure (1.5×10(8)Nm(-2)) that is required to cause cavitation in water. A corresponding acoustic particle acceleration (a) of 9.6×10(3)-1.5×10(4)ms(-2) was calculated i.e. approximately 984-1500 times greater than under the action of gravity.
    Matched MeSH terms: Enzymes, Immobilized*
  10. Poly(vinyl alcohol) : a potential matrix for glucose oxidase immobilization?
    Azila AA, Barbari T, Searson P
    Med J Malaysia, 2004 May;59 Suppl B:51-2.
    PMID: 15468814
    Considerable effort has been focused on the method of immobilizing glucose oxidase (GOD) for amperometric glucose biosensors since the technique employed may influence the available activity of the enzyme and thus affect the performance of the sensor. Narrow measuring range and low current response are still considered problems in this area. In this work, poly(vinyl alcohol)(PVA) was investigated as a potential matrix for GOD immobilization. GOD was entrapped in cross-linked PVA. The use of a PVA-GOD membrane as the enzymatic component of a glucose biosensor was found to be promising in both the magnitude of its signal and its relative stability over time. The optimum PVA-GOD membrane (cross-linking density of 0.06) was obtained through careful selection of the cross-linking density of the PVA matrix.
    Matched MeSH terms: Enzymes, Immobilized*
  11. Package plant of extended aeration membrane bioreactors: a study on aeration intensity and biofouling control
    Ujang Z, Ng SS, Nagaoka H
    Water Sci Technol, 2005;51(10):335-42.
    PMID: 16104438
    Biofouling control is important for effective process of membrane bioreactor (MBR). In this study, phenomena of biofouling for immersed type extended aeration MBR with two different anti-fouling aeration intensities were studied through a laboratory set up. The objectives of this study were (a) to observe biofouling phenomena of MBR that operates under different anti-fouling bubbling intensity, and simultaneously monitors performance of the MBR in organic carbon and nutrients removal; (b) to compare effectiveness of detergent and detergent-enzyme cleaning solutions in recovering biofouled membranes that operated in the extended aeration MBR. For MBR, which operated under continuous anti-fouling aeration, deposition and accumulation of suspended biomass on membrane surface were prohibited. However, flux loss was inescapable that biofilm layer was the main problem. Membrane cleaning was successfully carried out with detergent-enzyme mixture solutions and its effectiveness was compared with result from cleaning with just detergent solution.
    Matched MeSH terms: Enzymes/metabolism
  12. Immobilization of horseradish peroxidase on β-cyclodextrin-capped silver nanoparticles: Its future aspects in biosensor application
    Karim Z, Khan MJ, Maskat MY, Adnan R
    Prep Biochem Biotechnol, 2016 May 18;46(4):321-7.
    PMID: 25830286 DOI: 10.1080/10826068.2015.1031389
    This study aimed to work out a simple and high-yield procedure for the immobilization of horseradish peroxidase on silver nanoparticle. Ultraviolet-visible (UV-vis) and Fourier-transform infrared spectroscopy and transmission electron microscopy were used to characterize silver nanoparticles. Horseradish peroxidase was immobilized on β-cyclodextrin-capped silver nanoparticles via glutaraldehyde cross-linking. Single-cell gel electrophoresis (Comet assay) was also performed to confirm the genotoxicity of silver nanoparticles. To decrease toxicity, silver nanoparticles were capped with β-cyclodextrin. A comparative stability study of soluble and immobilized enzyme preparations was investigated against pH, temperature, and chaotropic agent, urea. The results showed that the cross-linked peroxidase was significantly more stable as compared to the soluble counterpart. The immobilized enzyme exhibited stable enzyme activities after repeated uses.
    Matched MeSH terms: Enzymes, Immobilized/metabolism*
  13. Kinetics study of palm oil hydrolysis using immobilized lipase Candida rugosa in packed bed reactor
    Min CS, Bhatia S, Kamaruddin AH
    Artif Cells Blood Substit Immobil Biotechnol, 1999 Sep-Nov;27(5-6):417-21.
    PMID: 10595442
    Continuous hydrolysis of palm oil triglyceride in organic solvent using immobilized Candida rugosa on the Amberlite MB-1 as a source of immobilized lipase was studied in packed bed reactor. The enzymatic kinetics of hydrolysis reaction was studied by changing the substrate concentration, reaction temperature and residence time(tau) in the reactor. At 55 degrees C, the optimum water concentration was found to be 15 % weight per volume of solution (%w/v). The Michaelis-Menten kinetic model was used to obtain the reaction parameters, Km(app) and V max(app). The activation energies were found to be quite low indicating that the lipase-catalyzed process is controlled by diffusion of substrates. The Michaelis-Menten kinetic model was found to be suitable at low water concentration 10-15 %w/v of solution. At higher water concentration, substrate inhibition model was used for data analysis. Reactor operation was found to play an important role in the palm oil hydrolysis kinetic.
    Matched MeSH terms: Enzymes, Immobilized/metabolism*
  14. Modeling and simulation of an enzymatic reactor for hydrolysis of palm oil
    Bhatia S, Naidu AD, Kamaruddin AH
    Artif Cells Blood Substit Immobil Biotechnol, 1999 Sep-Nov;27(5-6):435-40.
    PMID: 10595445
    Hydrolysis of palm oil has become an important process in Oleochemical industries. Therefore, an investigation was carried out for hydrolysis of palm oil to fatty acid and glycerol using immobilized lipase in packed bed reactor. The conversion vs. residence time data were used in Michaelis-Menten rate equation to evaluate the kinetic parameters. A mathematical model for the rate of palm oil hydrolysis was proposed incorporating role of external mass transfer and pore diffusion. The model was simulated for steady-state isothermal operation of immobilized lipase packed bed reactor. The experimental data were compared with the simulated results. External mass transfer was found to affect the rate of palm oil hydrolysis at higher residence time.
    Matched MeSH terms: Enzymes, Immobilized/metabolism*
  15. Covalent immobilization of aminoacylase to alginate for L-phenylalanine production
    Lee PM, Lee KH, Siaw YS
    J Chem Technol Biotechnol, 1993;58(1):65-70.
    PMID: 7763937
    Aminoacylase I (EC. 3.5.1.14) was immobilized by covalent crosslinking to alginate molecules with 1-ethyl-3-(3-dimethyl-aminopropyl)-carbodiimide HCl followed by calcium alginate bead formation for the production of L-phenylalanine from the racemic mixtures of N-acetyl-DL-phenylalanine. Different concentrations of the coupling reagent were tested and the coupling process was optimized. The immobilized and the partially purified aminoacylase were characterized in terms of the activity, operational stability, thermal stability, pH and temperature optima and kinetic constants, Km and Vmax. The activity of the enzyme covalently immobilized in calcium alginate beads was enhanced by about 75% compared to that of free enzyme. The beads showed stable activity under operational conditions, they lost about 40% of their activity after four reaction cycles. The immobilized aminoacylase was more stable over a broader pH range. Thus this simple method provides irreversible immobilization of aminoacylase to give a biocatalyst with good operational stability and enhanced activity.
    Matched MeSH terms: Enzymes, Immobilized/metabolism*
  16. Immobilization of aminoacylase in polyethyleneimine stabilized calcium alginate beads for L-phenylalanine production
    Lee PM, Lee KH, Siaw YS
    Biomater Artif Cells Immobilization Biotechnol, 1993;21(4):563-70.
    PMID: 8260581
    Aminoacylase I (E.C.3.5.1.14) was immobilized by entrapment in calcium alginate beads coated with polyethyleneimine for the production of L-phenylalanine by the hydrolysis of a racemic mixture of N-acetyl-DL-phenylalanine. The operational stability in terms of batch operation and continuous reaction in packed-bed bioreactor were studied. Kinetic constants, Km and Vmax values of free and immobilized enzymes were studied. Polyethyleneimine treatment was found to enhance the operational stability of the enzyme though its activity was substantially reduced. When polyethyleneimine-coated calcium alginate beads were packed into packed bed bioreactor, it was stable for at least 25 days under continuous operation without appreciable loss of activity.
    Matched MeSH terms: Enzymes, Immobilized/metabolism*
  17. Biochemical genetic relationship in three taxa of the malaria mosquito Anopheles balabacensis complex
    Yong HS, Cheong WH, Chiang GL, Dhaliwal SS, Loong KP, Sarjan R
    Comp. Biochem. Physiol., B, 1983;76(3):611-3.
    PMID: 6641178
    Three taxa of the malaria mosquito Anopheles balabacensis complex representing three geographical regions (Thailand, Peninsular Malaysia and Sabah) in Southeast Asia, were analysed for genetic variation at 15 gene-enzyme systems. The Sabah taxon was monomorphic for all the 15 gene-enzyme systems. Only two gene-enzyme systems (esterase and glucose phosphate isomerase) were variable in the Thailand and Peninsular Malaysia taxa. The average heterozygosity or gene diversity was 0.007 for the Thailand taxon and 0.028 for the Peninsular Malaysia (Perlis) taxon. There were no unique gene-enzyme markers in the three taxa studied. The average values of genetic identities (0.933-0.997) and genetic distances (0.003-0.069) indicate that these three taxa are of subspecific status.
    Matched MeSH terms: Enzymes/genetics*
  18. Optimized lipase-catalyzed synthesis of adipate ester in a solvent-free system
    Chaibakhsh N, Abdul Rahman MB, Abd-Aziz S, Basri M, Salleh AB, Abdul Rahman RN
    J Ind Microbiol Biotechnol, 2009 Sep;36(9):1149-55.
    PMID: 19479288 DOI: 10.1007/s10295-009-0596-x
    Immobilized Candida antarctica lipase-catalyzed esterification of adipic acid and oleyl alcohol was investigated in a solvent-free system (SFS). Optimum conditions for adipate ester synthesis in a stirred-tank reactor were determined by the response surface methodology (RSM) approach with respect to important reaction parameters including time, temperature, agitation speed, and amount of enzyme. A high conversion yield was achieved using low enzyme amounts of 2.5% w/w at 60 degrees C, reaction time of 438 min, and agitation speed of 500 rpm. The good correlation between predicted value (96.0%) and actual value (95.5%) implies that the model derived from RSM allows better understanding of the effect of important reaction parameters on the lipase-catalyzed synthesis of adipate ester in an organic solvent-free system. Higher volumetric productivity compared to a solvent-based system was also offered by SFS. The results demonstrate that the solvent-free system is efficient for enzymatic synthesis of adipate ester.
    Matched MeSH terms: Enzymes, Immobilized/metabolism*
  19. Recovery of value-added glycopeptides from edible bird's nest (EBN) co-products: enzymatic hydrolysis, physicochemical characteristics and bioactivity
    Ling JWA, Chang LS, Babji AS, Lim SJ
    J Sci Food Agric, 2020 Oct;100(13):4714-4722.
    PMID: 32468613 DOI: 10.1002/jsfa.10530
    BACKGROUND: Processing of edible bird's nest (EBN) requires extensive washing to remove impurities and produces huge amounts of EBN co-products, which contain mainly feathers with glycoproteins attached, which are usually discarded. This study was conducted to recover the valuable EBN glycoproteins from the waste material. Enzymatic hydrolysis was applied to recover EBN glycopeptides from EBN co-products (EBNcoP ) and processed cleaned EBN (EBNclean ) was used as control, which were then freeze-dried into EBN hydrolysates (EBNhcoP and EBNhclean , respectively).

    RESULTS: The recovery yield for EBNhclean and EBNhcoP were 89.09 ± 0.01% and 47.64 ± 0.26%, respectively, indicating nearly 50% of glycopeptide can be recovered from the waste material. Meanwhile, N-acetylneuraminic acid, a major acid sugar in EBN glycoproteins, of EBNhcoP increased by 229% from 58.6 ± 3.9 to 192.9 ± 3.1 g kg-1 , indicating the enzymatic hydrolysis removed impurities and thus enhanced the N-acetylneuraminic acid content. Total soluble protein was more than 330 g kg-1 for all the samples. Colour parameter showed that hydrolysate samples have greater L* (lightness) values. Chroma result indicates the intensity of all the samples were low (

    Matched MeSH terms: Enzymes/chemistry
  20. Enzymatic esterification of eugenol and benzoic acid by a novel chitosan-chitin nanowhiskers supported Rhizomucor miehei lipase: Process optimization and kinetic assessments
    Manan FMA, Attan N, Zakaria Z, Keyon ASA, Wahab RA
    Enzyme Microb Technol, 2018 Jan;108:42-52.
    PMID: 29108626 DOI: 10.1016/j.enzmictec.2017.09.004
    A biotechnological route via enzymatic esterification was proposed as an alternative way to synthesize the problematic anti-oxidant eugenyl benzoate. The new method overcomes the well-known drawbacks of the chemical route in favor of a more sustainable reaction process. The present work reports a Box-Behnken design (BBD) optimization process to synthesize eugenyl benzoate by esterification of eugenol and benzoic acid catalyzed by the chitosan-chitin nanowhiskers supported Rhizomucor miehei lipase (RML-CS/CNWs). Effects of four reaction parameters: reaction time, temperature, substrate molar ratio of eugenol: benzoic acid and enzyme loading were assessed. Under optimum conditions, a maximum conversion yield as high as 66% at 50°C in 5h using 3mg/mL of RML-CS/CNWs, and a substrate molar ratio (eugenol: benzoic acid) of 3:1. Kinetic assessments revealed the RML-CS/CNWs catalyzed the reaction via a ping-pong bi-bi mechanism with eugenol inhibition, characterized by a Vmax of 3.83mMmin-1. The Michaelis-Menten constants for benzoic acid (Km,A) and eugenol (Km,B) were 34.04 and 138.28mM, respectively. The inhibition constant for eugenol (Ki,B) was 438.6mM while the turnover number (kcat) for the RML-CS/CNWs-catalyzed esterification reaction was 40.39min-1. RML-CS/CNWs were reusable up to 8 esterification cycles and showed higher thermal stability than free RML.
    Matched MeSH terms: Enzymes, Immobilized/metabolism
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