Displaying publications 601 - 620 of 927 in total

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  1. Optimization of lignin peroxidase production and stability by Phanerochaete chrysosporium using sewage-treatment-plant sludge as substrate in a stirred-tank bioreactor
    Alam MZ, Mansor MF, Jalal KC
    J Ind Microbiol Biotechnol, 2009 May;36(5):757-64.
    PMID: 19259713 DOI: 10.1007/s10295-009-0548-5
    A laboratory-scale study was carried out to produce lignin peroxidase (ligninase) by white rot fungus (Phanerochaete chrysosporium) using sewage-treatment-plant (STP) sludge as the major substrate. The optimization was done using full-factorial design (FFD) with agitation and aeration as the two parameters. Nine experiments indicated by the FFD were fermented in a stirred-tank bioreactor for 3 days. A second-order quadratic model was developed using the regression analysis of the experimental results with the linear, quadratic, and interaction effects of the parameters. Analysis of variance (ANOVA) showed a high coefficient of determination (R (2)) value of 0.972, thus indicating a satisfactory fit of the quadratic model with the experimental data. Using statistical analysis, the optimum aeration and agitation rates were determined to be 2.0 vvm and 200 rpm, respectively, with a maximum activity of 225 U l(-1) in the first 3 days of fermentation. The validation experiment showed the maximum activity of lignin peroxidase was 744 U l(-1) after 5 days of fermentation. The results for the tests of the stability of lignin peroxidase showed that the activity was more than 80% of the maximum for the first 12 h of incubation at an optimum pH of 5 and temperature of 55 degrees C.
    Matched MeSH terms: Kinetics
  2. Batch and dynamic adsorption of lysozyme from chicken egg white on dye-affinity nanofiber membranes modified by ethylene diamine and chitosan
    Show PL, Ooi CW, Lee XJ, Yang CL, Liu BL, Chang YK
    Int J Biol Macromol, 2020 Nov 01;162:1711-1724.
    PMID: 32805284 DOI: 10.1016/j.ijbiomac.2020.08.065
    Adsorption of lysozyme on the dye-affinity nanofiber membranes was investigated in batch and dynamic modes. The membrane matrix was made of electrospun polyacrylonitrile nanofibers that were grafted with ethylene diamine (EDA) and/or chitosan (CS) for the coupling of Reactive Blue 49 dye. The physicochemical properties of these dye-immobilized nanofiber membranes (P-EDA-Dye and P-CS-Dye) were characterized microscopically, spectroscopically and thermogravimetrically. The capacities of lysozyme adsorption by the dye-affinity nanofiber membranes were evaluated under various conditions, namely pH, dye immobilized density, and loading flow rate. The adsorption of lysozyme to the dye-affinity nanofiber membranes was well fitted by Langmuir isotherm and pseudo-second kinetic models. P-CS-Dye nanofiber membrane had a better performance in the dynamic adsorption of lysozyme from complex chicken egg white solution. It was observed that after five cycles of adsorption-desorption, the dye-affinity nanofiber membrane did not show a significant loss in its capacity for lysozyme adsorption. The robustness as well as high dynamic adsorption capability of P-CS-Dye nanofiber membrane are promising for the efficient recovery of lysozyme from complex feedstock via nanofiber membrane chromatography.
    Matched MeSH terms: Kinetics
  3. Comparison between procaine and isocarboxazid metabolism in vitro by a liver microsomal amidase-esterase
    Moroi K, Sato T
    Biochem Pharmacol, 1975 Aug 15;24(16):1517-21.
    PMID: 8
    Matched MeSH terms: Kinetics
  4. Fulltext Combined Optimization of Codon Usage and Glycine Supplementation Enhances the Extracellular Production of a β-Cyclodextrin Glycosyltransferase from Bacillus sp. NR5 UPM in Escherichia coli
    Nik-Pa NIM, Sobri MFM, Abd-Aziz S, Ibrahim MF, Kamal Bahrin E, Mohammed Alitheen NB, et al.
    Int J Mol Sci, 2020 May 30;21(11).
    PMID: 32486212 DOI: 10.3390/ijms21113919
    Two optimization strategies, codon usage modification and glycine supplementation, were adopted to improve the extracellular production of Bacillus sp. NR5 UPM β-cyclodextrin glycosyltransferase (CGT-BS) in recombinant Escherichia coli. Several rare codons were eliminated and replaced with the ones favored by E. coli cells, resulting in an increased codon adaptation index (CAI) from 0.67 to 0.78. The cultivation of the codon modified recombinant E. coli following optimization of glycine supplementation enhanced the secretion of β-CGTase activity up to 2.2-fold at 12 h of cultivation as compared to the control. β-CGTase secreted into the culture medium by the transformant reached 65.524 U/mL at post-induction temperature of 37 °C with addition of 1.2 mM glycine and induced at 2 h of cultivation. A 20.1-fold purity of the recombinant β-CGTase was obtained when purified through a combination of diafiltration and nickel-nitrilotriacetic acid (Ni-NTA) affinity chromatography. This combined strategy doubled the extracellular β-CGTase production when compared to the single approach, hence offering the potential of enhancing the expression of extracellular enzymes, particularly β-CGTase by the recombinant E. coli.
    Matched MeSH terms: Kinetics
  5. Optimization strategy for laccase immobilization on polyethylene terephthalate grafted with maleic anhydride electrospun nanofiber mat
    Mohd Syukri MS, A Rahman R, Mohamad Z, Md Illias R, Nik Mahmood NA, Jaafar NR
    Int J Biol Macromol, 2021 Jan 01;166:876-883.
    PMID: 33144251 DOI: 10.1016/j.ijbiomac.2020.10.244
    Enzyme immobilization has been known to be one of the methods to improve the stability and reusability of enzyme. In this study, a strategy to optimize laccase immobilization on polyethylene terephthalate grafted with maleic anhydride electrospun nanofiber mat (PET-g-MAH ENM) was developed. The development involves the screening and optimization processes of the crucial factors that influence the immobilization yield such as enzyme concentration, pH values, covalent bonding (CV) time, CV temperature, crosslinking (CL) time, CL temperature and glutaraldehyde concentration using two-level factorial design and Box-Behnken design (BBD), respectively. It was found that laccase concentration, pH values and glutaraldehyde concentration play important role in enhancing the immobilization yield of laccase on PET-g-MAH ENM in the screening process. Subsequently, the optimization result showed at 0.28 mg/ml laccase concentration, pH 3 and 0.45% (v/v) glutaraldehyde concentrations gave the highest immobilization yield at 87.64% which was 81.2% increment from the immobilization yield before optimization. Under the optimum condition, the immobilized laccase was able to oxidize 2, 2-azino-bis 3-ethylbenzothiazoline-6- sulfonic acid (ABTS) in a broad range of pH (pH 3-6) and temperature (20- 70 °C). Meanwhile, the kinetic parameters for Km and Vmax were 1.331 mM and 0.041 mM/min, respectively. It was concluded that the optimization of immobilized laccase on PET-g-MAH ENM enhance the performance of this biocatalyst.
    Matched MeSH terms: Kinetics
  6. Removal of cationic dye waste by nanofiber membrane immobilized with waste proteins
    Huong DTM, Chai WS, Show PL, Lin YL, Chiu CY, Tsai SL, et al.
    Int J Biol Macromol, 2020 Dec 01;164:3873-3884.
    PMID: 32896561 DOI: 10.1016/j.ijbiomac.2020.09.020
    Water pollution caused by dyes has been a serious problem affecting human health and environment. The surface of polyacrylonitrile (PAN) nanofiber membranes was modified by mild hydrolysis and coupled with bovine serum albumin (BSA) obtained from the laboratory wastes, resulting in the synthesis of P-COOH and P-COOH-BSA nanofibers. The nanofibers with specific functional groups may enhance their potential applications toward the removal of ionic dyes in wastewater. Toluidine blue O (TBO) was applied as an example of cationic dye to evaluate the removal efficiency of P-COOH-BSA nanofiber. Results showed that the equilibrium dissociation constant and maximum removal capacity were 0.48 mg/mL and 434.78 mg/g, respectively, at pH 12, where the TBO removal can be explained based on Langmuir isotherm and pseudo-second-order model. Desorption studies have shown that TBO adsorbed on P-COOH-BSA protein membrane can be completely eluted with either 1 M NaCl or 50% glycerol. The results of repeated studies indicated that after five consecutive adsorption/desorption cycles, the removal efficiency of TBO can be maintained at ~97%. P-COOH-BSA has shown to be promising adsorbent in TBO dye removal from dye wastewater.
    Matched MeSH terms: Kinetics
  7. Fulltext Adsorption Studies of Volatile Organic Compound (Naphthalene) from Aqueous Effluents: Chemical Activation Process Using Weak Lewis Acid, Equilibrium Kinetics and Isotherm Modelling
    Akinpelu AA, Chowdhury ZZ, Shibly SM, Faisal ANM, Badruddin IA, Rahman MM, et al.
    Int J Mol Sci, 2021 Feb 19;22(4).
    PMID: 33669883 DOI: 10.3390/ijms22042090
    This study deals with the preparation of activated carbon (CDSP) from date seed powder (DSP) by chemical activation to eliminate polyaromatic hydrocarbon-PAHs (naphthalene-C10H8) from synthetic wastewater. The chemical activation process was carried out using a weak Lewis acid of zinc acetate dihydrate salt (Zn(CH3CO2)2·2H2O). The equilibrium isotherm and kinetics analysis was carried out using DSP and CDSP samples, and their performances were compared for the removal of a volatile organic compound-naphthalene (C10H8)-from synthetic aqueous effluents or wastewater. The equilibrium isotherm data was analyzed using the linear regression model of the Langmuir, Freundlich and Temkin equations. The R2 values for the Langmuir isotherm were 0.93 and 0.99 for naphthalene (C10H8) adsorption using DSP and CDSP, respectively. CDSP showed a higher equilibrium sorption capacity (qe) of 379.64 µg/g. DSP had an equilibrium sorption capacity of 369.06 µg/g for C10H8. The rate of reaction was estimated for C10H8 adsorption using a pseudo-first order, pseudo-second order and Elovich kinetic equation. The reaction mechanism for both the sorbents (CDSP and DSP) was studied using the intraparticle diffusion model. The equilibrium data was well-fitted with the pseudo-second order kinetics model showing the chemisorption nature of the equilibrium system. CDSP showed a higher sorption performance than DSP due to its higher BET surface area and carbon content. Physiochemical characterizations of the DSP and CDSP samples were carried out using the BET surface area analysis, Fourier-scanning microscopic analysis (FSEM), energy-dispersive X-ray (EDX) analysis and Fourier-transform spectroscopic analysis (FTIR). A thermogravimetric and ultimate analysis was also carried out to determine the carbon content in both the sorbents (DSP and CDSP) here. This study confirms the potential of DSP and CDSP to remove C10H8 from lab-scale synthetic wastewater.
    Matched MeSH terms: Kinetics
  8. Fulltext Kinetics Growth and Recovery of Valuable Nutrients from Selangor Peat Swamp and Pristine Forest Soils Using Different Extraction Methods as Potential Microalgae Growth Enhancers
    Yaacob NS, Ahmad MF, Kawasaki N, Maniyam MN, Abdullah H, Hashim EF, et al.
    Molecules, 2021 Jan 27;26(3).
    PMID: 33513787 DOI: 10.3390/molecules26030653
    Soil extracts are useful nutrients to enhance the growth of microalgae. Therefore, the present study attempts for the use of virgin soils from Peninsular Malaysia as growth enhancer. Soils collected from Raja Musa Forest Reserve (RMFR) and Ayer Hitam Forest Reserve (AHFR) were treated using different extraction methods. The total dissolved nitrogen (TDN), total dissolved phosphorus (TDP), and dissolved organic carbon (DOC) concentrations in the autoclave methods were relatively higher than natural extraction with up to 132.0 mg N/L, 10.7 mg P/L, and 2629 mg C/L, respectively for RMFR. The results of TDN, TDP, and DOC suggested that the best extraction methods are autoclaved at 121 °C twice with increasing 87%, 84%, and 95%, respectively. Chlorella vulgaris TRG 4C dominated the growth at 121 °C twice extraction method in the RMRF and AHRF samples, with increasing 54.3% and 14%, respectively. The specific growth rate (µ) of both microalgae were relatively higher, 0.23 d-1 in the Ayer Hitam Soil. This extract served well as a microalgal growth promoter, reducing the cost and the needs for synthetic medium. Mass production of microalgae as aquatic feed will be attempted eventually. The high recovery rate of nutrients has a huge potential to serve as a growth promoter for microalgae.
    Matched MeSH terms: Kinetics
  9. Enhanced removal of Orange G from aqueous solutions by modified chitosan beads: Performance and mechanism
    Sutirman ZA, Sanagi MM, Abd Karim KJ, Abu Naim A, Wan Ibrahim WA
    Int J Biol Macromol, 2019 Jul 15;133:1260-1267.
    PMID: 31047925 DOI: 10.1016/j.ijbiomac.2019.04.188
    Grafting of crosslinked chitosan with monomer, N-vinyl-2-pyrrolidone, has been carried out to investigate its adsorption capacity toward Orange G (OG) from aqueous solutions. The adsorption performance of modified chitosan (cts(x)-g-PNVP) was examined and compared with that of the unmodified chitosan. The effects of initial pH, contact time and initial dye concentration were investigated in a batch system. The experimental data were correlated with the Langmuir and Freundlich isotherm models. The maximum adsorption capacity of cts(x)-g-PNVP (63.7mgg-1) based on Langmuir equation was relatively higher than that of the unmodified chitosan (1.7mgg-1). The kinetic studies showed that the adsorption process was consistent with the pseudo-second order kinetic model. Interaction mechanisms between OG and cts(x)-g-PNVP were also proposed. The overall results suggested that the prepared cts(x)-g-PNVP stands a good candidate as adsorbent for removal of anionic dye from aqueous solutions.
    Matched MeSH terms: Kinetics
  10. Preparation of letrozole dispersed pHEMA/AAm-g-LDPE drug release system: In-vitro release kinetics for the treatment of endometriosis
    Siddiqa AJ, Shrivastava NK, Ali Mohsin ME, Abidi MH, Shaikh TA, El-Meligy MA
    Colloids Surf B Biointerfaces, 2019 Jul 01;179:445-452.
    PMID: 31005739 DOI: 10.1016/j.colsurfb.2019.04.014
    This paper focuses on the development of a drug delivery system for systemically controlled release of a poorly soluble drug, letrozole. The work meticulously describes the preparation and characterizations of 2-hydroxyethyl methacrylate (HEMA) polymerization onto hydrophilic acrylamide grafted low-density polyethylene (AAm-g-LDPE) surface for targeted drug release system. The surface morphology and thickness measurement of coated pHEMA layer were measured using scanning electron microscopy (SEM). The swelling study was done in deionized (DI) water and simulated uterine fluid (SUF, pH = 7.6). In vitro release of letrozole from the system was performed in SUF. Further, the release kinetics of letrozole from the system was studied using different mathematical models. The results, suggest that the rate of drug release can be altered by varying the concentrations of cross-linker in pHEMA. The optimized sample released 72% drug at the end of 72 h of measurement.
    Matched MeSH terms: Kinetics
  11. Hylocereus polyrhizus peel's high-methoxyl pectin: A potential source of hypolipidemic agent
    Zaid RM, Mishra P, Wahid ZA, Sakinah AMM
    Int J Biol Macromol, 2019 Aug 01;134:361-367.
    PMID: 31059740 DOI: 10.1016/j.ijbiomac.2019.03.143
    In the present study, high-methoxyl pectin (HMP) was extracted from Hylocereus polyrhizus peel's using physico-chemical process. In addition, the hypolipidemic activity of HMP was investigated at different concentration and time corresponding to its adsorption ability. FTIR and contact angle analysis were used to determine the sorbent characterization. A high degree of esterification (63.8%) and the contact angle (95.5°) confirmed hydrophobic nature and resulting bad wetting of the HMP extract, respectively. The methoxyl content in the pectin acted as an affinity-precursor of the pectin towards cholesterol due to its increased hydrophobicity. The maximum equilibrium uptake capacity of cholesterol of 370.5mg/g (0.96mmol/g) was observed by HMP. The experimental data showed good fitting for Freundlich isotherm equation and followed pseudo-first-order kinetic model with a correlation coefficient (R2) of 0.89-0.97 due to physisorption mechanism. Intra-particle model confirmed that the cholesterol sorption rate by HMP was significantly influenced by external mass transfer (surface diffusion) and intra-particle diffusion (diffusion control). It was also revealed that the HMP extracted from Hylocereus polyrhizus peels possess a high affinity towards cholesterol, making it an ideal hypolipidemic agent.
    Matched MeSH terms: Kinetics
  12. Robust Magnetized Oil Palm Leaves Ash Nanosilica Composite as Lipase Support: Immobilization Protocol and Efficacy Study
    Onoja E, Wahab RA
    Appl Biochem Biotechnol, 2020 Oct;192(2):585-599.
    PMID: 32495234 DOI: 10.1007/s12010-020-03348-0
    Strategies to immobilize the individual enzymes are crucial for enhancing catalytic applicability and require a controlled immobilization process. Herein, protocol for immobilizing Candida rugosa lipase (CRL) onto modified magnetic silica derived from oil palm leaves ash (OPLA) was optimized for the effects of concentration of CRL, immobilization time, and temperature, monitored by titrimetric and spectrometric methods. XRD and TGA-DTG spectrometric observations indicated that OPLA-silica was well coated over magnetite (SiO2-MNPs) and CRLs were uniformly bound by covalent bonds to SiO2-MNPs (CRL/Gl-A-SiO2-MNPs). The optimized immobilization protocol showed that in the preparation of CRL/Gl-A-SiO2-MNPs, CRL with 68.3 mg/g protein loading and 74.6 U/g specific activity was achieved using 5 mg/mL of CRL, with an immobilization time of 12 h at 25 °C. The present work also demonstrated that acid-pretreated OPLA is a potential source of renewable silica, envisioning its applicability for practical use in enzymatic catalysis on solid support.
    Matched MeSH terms: Kinetics
  13. Binding Hotspot and Activation Mechanism of Maltitol and Lactitol toward the Human Sweet Taste Receptor
    Mahalapbutr P, Lee VS, Rungrotmongkol T
    J Agric Food Chem, 2020 Jul 29;68(30):7974-7983.
    PMID: 32551626 DOI: 10.1021/acs.jafc.0c02580
    Human sweet taste receptor (hSTR) recognizes a wide array of sweeteners, resulting in sweet taste perception. Maltitol and lactitol have been extensively used in place of sucrose due to their capability to prevent dental caries. Herein, several molecular modeling approaches were applied to investigate the structural and energetic properties of these two polyols/hSTR complexes. Triplicate 500 ns molecular dynamics (MD) simulations and molecular mechanics/generalized Born surface area (MM/GBSA)-based free energy calculations revealed that the TAS1R2 monomer is the preferential binding site for maltitol and lactitol rather than the TAS1R3 region. Several polar residues (D142, S144, Y215, D278, E302, R383, and especially N143) were involved in polyols binding through electrostatic attractions and H-bond formations. The molecular complexation process not only induced the stable form of ligands but also stimulated the conformational adaptation of the TAS1R2 monomer to become a close-packed structure through an induced-fit mechanism. Notably, the binding affinity of the maltitol/TAS1R2 complex (ΔGbind of -17.93 ± 1.49 kcal/mol) was significantly higher than that of the lactitol/TAS1R2 system (-8.53 ± 1.78 kcal/mol), in line with the experimental relative sweetness. These findings provide an in-depth understanding of the differences in the sweetness response between maltitol and lactitol, which could be helpful to design novel polyol derivatives with higher sweet taste perception.
    Matched MeSH terms: Kinetics
  14. Burkholderia vietnamiensis isolated from root tissues of Nipa Palm (Nypa fruticans) in Sarawak, Malaysia, proved to be its major endophytic nitrogen-fixing bacterium
    Tang SY, Hara S, Melling L, Goh KJ, Hashidoko Y
    Biosci Biotechnol Biochem, 2010;74(9):1972-5.
    PMID: 20834139
    Root-associating bacteria of the nipa palm (Nypa fruticans), preferring brackish-water affected mud in Sarawak, Malaysia, were investigated. In a comparison of rhizobacterial microbiota between the nipa and the sago (Metroxylon sagu) palm, it was found that the nipa palm possessed a group of Burkholderia vietnamiensis as its main active nitrogen-fixing endophytic bacterium. Acetylene reduction by the various isolates of B. vietnamiensis was constant (44 to 68 nmol h(-1) in ethylene production rate) in soft gel medium containing 0.2% sucrose as sole carbon source, and the bacterium also showed motility and biofilm-forming capacity. This is the first report of endophytic nitrogen-fixing bacteria from nipa palm.
    Matched MeSH terms: Kinetics
  15. Smart pH-responsive co-polymeric hydrogels for controlled delivery of capecitabine: Fabrication, Optimization and in vivo toxicology screening
    Rehman U, Sarfraz RM, Mahmood A, Hussain Z, Thu HE, Zafar N, et al.
    Curr Drug Deliv, 2021 Feb 11.
    PMID: 33583374 DOI: 10.2174/1567201818666210212085912
    BACKGROUND: Despite exhibiting promising anticancer potential, the clinical significance of capecitabine (a potent prodrug of 5-fluorouracil used for treatment of colorectal cancer) is limited owing to its acidic and enzymatic hydrolysis, lower absorption following the oral administration, poor bioavailability, short plasma half-life and poor patient compliance.

    OBJECTIVES: The present study was aimed to fabricate the capecitabine as smart pH-responsive hydrogel network to efficiently facilitate its oral delivery while shielding its stability in the gastric media.

    METHODS: The smart pH sensitive HP-β-CD/agarose-g-poly(MAA) hydrogel network was developed using an aqueous free radical polymerization technique. The developed hydrogels were characterized for drug-loading efficiency, structural and compositional features, thermal stability, swelling behaviour, morphology, physical form, and release kinetics. The pH-responsive behaviour of developed hydrogels was established by conducting the swelling and release behaviour at different pH values (1.2 and 7.4), demonstrating significantly higher swelling and release at pH 7.4 as compared with pH 1.2. The capecitabine-loaded hydrogels were also screened for acute oral toxicity in animals by analysing the body weight, water and food intake, dermal toxicity, ocular toxicity, biochemical analysis, and histological examination.

    RESULTS: The characteristic evaluations revealed that capecitabine (anticancer agent) was successfully loaded into the hydrogel network. Capecitabine loading was ranged from 71.22% to 90.12%. An interesting feature of hydrogel was its pH-responsive behaviour which triggers release at basic pH (94.25%). Optimum swelling (95%) was seen at pH 7.4. Based upon regression coefficient R2 (0.96 - 0.99) best fit model was zero order. The extensive toxicity evaluations evidenced good safety profile with no signs of oral, dermal or ocular toxicities, as well as no variations in blood parameters and histology of vital organs.

    CONCLUSION: Our findings conclusively evinced that the developed hydrogel exhibited excellent pharmaceutical and therapeutic potential and thus can be employed as pH-responsive system for controlled delivery of anticancer agents.

    Matched MeSH terms: Kinetics
  16. Fulltext Characterization and multi-step transketolase-ω-transaminase bioconversions in an immobilized enzyme microreactor (IEMR) with packed tube
    Halim AA, Szita N, Baganz F
    J Biotechnol, 2013 Dec;168(4):567-75.
    PMID: 24055435 DOI: 10.1016/j.jbiotec.2013.09.001
    The concept of de novo metabolic engineering through novel synthetic pathways offers new directions for multi-step enzymatic synthesis of complex molecules. This has been complemented by recent progress in performing enzymatic reactions using immobilized enzyme microreactors (IEMR). This work is concerned with the construction of de novo designed enzyme pathways in a microreactor synthesizing chiral molecules. An interesting compound, commonly used as the building block in several pharmaceutical syntheses, is a single diastereoisomer of 2-amino-1,3,4-butanetriol (ABT). This chiral amino alcohol can be synthesized from simple achiral substrates using two enzymes, transketolase (TK) and transaminase (TAm). Here we describe the development of an IEMR using His6-tagged TK and TAm immobilized onto Ni-NTA agarose beads and packed into tubes to enable multi-step enzyme reactions. The kinetic parameters of both enzymes were first determined using single IEMRs evaluated by a kinetic model developed for packed bed reactors. The Km(app) for both enzymes appeared to be flow rate dependent, while the turnover number kcat was reduced 3 fold compared to solution-phase TK and TAm reactions. For the multi-step enzyme reaction, single IEMRs were cascaded in series, whereby the first enzyme, TK, catalyzed a model reaction of lithium-hydroxypyruvate (HPA) and glycolaldehyde (GA) to L-erythrulose (ERY), and the second unit of the IEMR with immobilized TAm converted ERY into ABT using (S)-α-methylbenzylamine (MBA) as amine donor. With initial 60mM (HPA and GA each) and 6mM (MBA) substrate concentration mixture, the coupled reaction reached approximately 83% conversion in 20 min at the lowest flow rate. The ability to synthesize a chiral pharmaceutical intermediate, ABT in relatively short time proves this IEMR system as a powerful tool for construction and evaluation of de novo pathways as well as for determination of enzyme kinetics.
    Matched MeSH terms: Kinetics
  17. Fulltext Production of Biodegradable Polymer from Agro-Wastes in Alcaligenes sp. and Pseudomonas sp
    Sayyed RZ, Shaikh SS, Wani SJ, Rehman MT, Al Ajmi MF, Haque S, et al.
    Molecules, 2021 Apr 22;26(9).
    PMID: 33922162 DOI: 10.3390/molecules26092443
    The present study was aimed to evaluate the suitability of agro-wastes and crude vegetable oils for the cost-effective production of poly-β-hydroxybutyrate (PHB), to evaluate growth kinetics and PHB production in Alcaligenes faecalis RZS4 and Pseudomonas sp. RZS1 with these carbon substrates and to study the biodegradation of PHB accumulated by these cultures. Alcaligenes faecalis RZS4 and Pseudomonas sp. RZS1 accumulates higher amounts of PHB corn (79.90% of dry cell mass) and rice straw (66.22% of dry cell mass) medium respectively. The kinetic model suggests that the Pseudomonas sp. RZS1 follows the Monod model more closely than A. faecalis RZS4. Both the cultures degrade their PHB extract under the influence of PHB depolymerase. Corn waste and rice straw appear as the best and cost-effective substrates for the sustainable production of PHB from Alcaligenes faecalis RZS4 and Pseudomonas sp. RZS1. The biopolymer accumulated by these organisms is biodegradable in nature. The agro-wastes and crude vegetable oils are good and low-cost sources of nutrients for the growth and production of PHB and other metabolites. Their use would lower the production cost of PHB and the low-cost production will reduce the sailing price of PHB-based products. This would promote the large-scale commercialization and popularization of PHB as an ecofriendly bioplastic/biopolymer.
    Matched MeSH terms: Kinetics
  18. Effect of operative variables and kinetic study of butyl butyrate synthesis by Candida rugosa lipase activated by chitosan-reinforced nanocellulose derived from raw oil palm leaves
    Elias N, Wahab RA, Chandren S, Abdul Razak FI, Jamalis J
    Enzyme Microb Technol, 2019 Nov;130:109367.
    PMID: 31421729 DOI: 10.1016/j.enzmictec.2019.109367
    Currently, the chemically-assisted esterification to manufacture butyl butyrate employs corrosive homogeneous acid catalyst and liberates enormous quantities of hazardous by-products which complicate downstream treatment processes. This study aimed to identify the optimized esterification conditions, and the kinetic aspects of the enzyme-assisted synthesis of butyl butyrate using immobilized Candida rugosa lipase activated by chitosan-reinforced nanocellulose derived from raw oil palm leaves (CRL/CS-NC). The best process variables that gave the maximum conversion degree of butyl butyrate by CRL/CS-NC (90.2%) in just 3 h, as compared to free CRL (62.9%) are as follows: 50 °C, 1:2 M ratio of acid/alcohol, stirring rate of 200 rpm and a 3 mg/mL enzyme load. The enzymatic esterification followed the ping pong bi-bi mechanism with substrate inhibition, revealing a ˜1.1-fold higher Ki for CRL/CS-NC (55.55 mM) over free CRL (50.68 mM). This indicated that CRL/CS-NC was less inhibited by the substrates. Butanol was preferred over butyric acid as reflected by the higher apparent Michaelis-Menten constant of CRL/CS-NC for butanol (137 mM) than butyric acid (142.7 mM). Thus, the kinetics data conclusively showed that CRL/CS-NC (Vmax 0.48 mM min-1, Keff 0.07 min-1 mM-1) was catalytically more efficient than free CRL (Vmax 0.35 mM min-1, Keff 0.06 min-1 mM-1).
    Matched MeSH terms: Kinetics
  19. 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: Kinetics
  20. Oral Nanoemulsion of Fenofibrate: Formulation, Characterization, and In Vitro Drug Release Studies
    Gulati N, Kumar Chellappan D, M Tambuwala M, A A Aljabali A, Prasher P, Kumar Singh S, et al.
    Assay Drug Dev Technol, 2021 05 14;19(4):246-261.
    PMID: 33989048 DOI: 10.1089/adt.2021.012
    Nanoemulsions (NMs) are one of the most important colloidal dispersion systems that are primarily used to improve the solubility of poorly water soluble drugs. The main objectives of this study were, first, to prepare an NM loaded with fenofibrate using a high shear homogenization technique and, second, to study the effect of variable using a central composite design. Twenty batches of fenofibrate-loaded NM formulations were prepared. The formed NMs were subjected to droplet size analysis, zeta potential, entrapment efficiency, pH, dilution, polydispersity index, transmission electron microscopy (TEM), Fourier transform infrared spectrophotometry, differential scanning calorimetry (DSC), and in vitro drug release study. Analysis of variance was used for entrapment efficiency data to study the fitness and significance of the design. The NM-7 batch formulation demonstrated maximum entrapment efficiency (81.82%) with lowest droplet size (72.28 nm), and was thus chosen as the optimized batch. TEM analysis revealed that the NM was well dispersed with droplet sizes <100 nm. Incorporation of the drug into the NM was confirmed with DSC studies. In addition, the batch NM-7 also showed the maximum in vitro drug release (87.6%) in a 0.05 M sodium lauryl sulfate solution. The release data revealed that the NM followed first-order kinetics. The outcomes of the study revealed the development of a stable oral NM containing fenofibrate using the high shear homogenization technique. This approach may aid in further enhancing the oral bioavailability of fenofibrate, which requires further in vivo studies.
    Matched MeSH terms: Kinetics
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