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Ondo D. Thermodynamic study on complexation of long-chain fatty acid anions with α-cyclodextrin in water. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.113172] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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María Belén V, Adrián M, Francisco GC, José Manuel LN. Nanoencapsulation as fluorescence enhancer of vitamin L1 (anthranilic acid). An exhaustive study. Food Hydrocoll 2019. [DOI: 10.1016/j.foodhyd.2019.01.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abril- Sánchez C, Matencio A, Navarro-Orcajada S, García-Carmona F, López-Nicolás JM. Evaluation of the properties of the essential oil citronellal nanoencapsulated by cyclodextrins. Chem Phys Lipids 2019; 219:72-78. [DOI: 10.1016/j.chemphyslip.2019.02.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 02/05/2019] [Accepted: 02/10/2019] [Indexed: 01/22/2023]
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Matencio A, Bermejo-Gimeno MJ, García-Carmona F, López-Nicolás JM. Separating and Identifying the Four Stereoisomers of Methyl Jasmonate by RP-HPLC and using Cyclodextrins in a Novel Way. PHYTOCHEMICAL ANALYSIS : PCA 2017; 28:151-158. [PMID: 27910224 DOI: 10.1002/pca.2654] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 09/21/2016] [Accepted: 09/25/2016] [Indexed: 06/06/2023]
Abstract
INTRODUCTION Several authors have reported on the different bioactivities of methyl jasmonate (MeJA) stereoisomers. However, no simple, precise and cheap method for separating and identifying them using reversed-phase high performance liquid chromatography (RP-HPLC) has been developed. OBJECTIVE (1) To create a simple, precise and cheap method for separating and identifying the four stereoisomers present in commercial racemic mixtures of MeJA and (2) to identify the four stereoisomers using molecular docking techniques and coinjection. Materials and Methods - RP-HPLC using a 250 mm C18 column and different proportions of cyclodextrins (CDs) and organic solvents was applied to a commercial sample of racemic MeJA. RESULTS The results show that the best conditions for separating the MeJA stereoisomers are: 20% methanol in the mobile phase, a temperature of 45 °C and a 16 mM concentration of methyl-β-cyclodextrin (M-β-CD). A simple C18 250 mm column and a flow rate of 1.25 mL/min were used. The reduction in the retention time of MeJA observed when M-β-CD is added to the mobile phases was used to determine the complexation constants of the guest/CD complex and compared with the obtained when other CDs were used. The KF for M-β-CD (117.49 ± 5.9 1/M) was obtained with a 1:1 stoichiometry. The four stereoisomers were identified by molecular docking techniques and coinjection of a commercially available rosemary essential oil. CONCLUSION The new method identified and classified the four stereoisomers of MeJA in the following ordination: (-)epiMeJA, (-)MeJA; (+)MeJA and (+)epiMeJA. These results could be used to improve the elicitation of cell cultures with only the best isomer. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Adrián Matencio
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Murcia, Campus de Espinardo, 30071, Murcia, Spain
| | - Mario J Bermejo-Gimeno
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Murcia, Campus de Espinardo, 30071, Murcia, Spain
| | - Francisco García-Carmona
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Murcia, Campus de Espinardo, 30071, Murcia, Spain
| | - José Manuel López-Nicolás
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Murcia, Campus de Espinardo, 30071, Murcia, Spain
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Aggregation of t10,c12 conjugated linoleic Acid in presence of natural and modified cyclodextrins. A physicochemical, thermal and computational analysis. Chem Phys Lipids 2017; 204:57-64. [DOI: 10.1016/j.chemphyslip.2017.03.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 03/08/2017] [Accepted: 03/23/2017] [Indexed: 11/22/2022]
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Matencio A, Hernández-Gil CJG, García-Carmona F, López-Nicolás JM. Physicochemical, thermal and computational study of the encapsulation of rumenic acid by natural and modified cyclodextrins. Food Chem 2017; 216:289-95. [DOI: 10.1016/j.foodchem.2016.08.023] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 08/06/2016] [Accepted: 08/08/2016] [Indexed: 12/12/2022]
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Matencio A, García-Carmona F, López-Nicolás JM. Encapsulation of piceatannol, a naturally occurring hydroxylated analogue of resveratrol, by natural and modified cyclodextrins. Food Funct 2016; 7:2367-73. [PMID: 27142512 DOI: 10.1039/c6fo00557h] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In this work, an in-depth study of the interaction between piceatannol (a type of stilbene with high biological activity) and different natural and modified cyclodextrins (CDs) is made, using steady state fluorescence. This bioactive molecule forms a 1 : 1 complex with all the natural (α-CD, β-CD and γ-CD) and modified (HP-β-CD, HE-β-CD and M-β-CD) CDs tested. Among natural CDs, the interaction of piceatannol with β-CD was the most efficient. However, the modified CDs showed higher encapsulation constants (KF) than β-CD, except M-β-CD; the highest KF being found for HP-β-CD (14 048 ± 702 M(-1)). The encapsulation of piceatannol in the internal cavity of CDs showed a strong dependence on pH and temperature. The interaction between HP-β-CD and piceatannol was less effective in the pH region where the stilbene begins to suffer the deprotonation of its hydroxyl group. Moreover, the values of KF decreased as the system temperature increased. To obtain information on the mechanism involved in the piceatannol affinity for CD, the thermodynamic parameters of the complexation (ΔH°, ΔS° and ΔG°) were studied, the results showed a negative entropy (-3.7 ± 0.2 J mol(-1) K(-1)), enthalpy (-24.6 ± 1.2 kJ mol(-1)) and Gibbs free energy change at 25 °C (-23.5 ± 1.2 J mol(-1)). Finally, molecular docking calculations provided further insights into how the different interactions influence the complexation constant. A high degree of correlation was observed between the computed scores and experimental values.
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Affiliation(s)
- Adrián Matencio
- Department of Biochemistry and Molecular Biology-A, Faculty of Biology, University of Murcia, Campus de Espinardo, 30071, Murcia, Spain.
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Vestland TL, Jacobsen Ø, Sande SA, Myrset AH, Klaveness J. Characterization of omega-3 tablets. Food Chem 2015; 197:496-502. [PMID: 26616980 DOI: 10.1016/j.foodchem.2015.10.142] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2015] [Revised: 10/02/2015] [Accepted: 10/29/2015] [Indexed: 10/22/2022]
Abstract
Omega-3 nutraceuticals are extensively used as health supplements worldwide. Various administration forms for delivery of omega-3 are available. However, the niche omega-3 tablets have so far remained unexplored. In this work tablets containing 25-40% (w/w) omega-3 oil as triglycerides or ethyl esters were prepared utilizing a direct compaction grade powder with β-cyclodextrin as encapsulating agent. It was found that powders with up to 35% (w/w) triglyceride oil and 30% (w/w) ethyl ester oil, respectively, can be directly compressed into tablets of excellent quality. Physical properties of omega-3 containing powders and tablets are described. The powder X-ray diffractograms of the powders and crushed tablets show evidence of the formation of new crystalline phases not present in β-cyclodextrin. In addition, (1)H NMR data suggest that the ethyl esters form inclusion complexes with β-cyclodextrin. Compaction of other, commercially available, omega-3 powders was performed as a comparison and deemed unsuccessful.
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Affiliation(s)
- Tina Lien Vestland
- Omegatri AS, P.O. Box 4849 Nydalen, 0422 Oslo, Norway; School of Pharmacy, University of Oslo, P.O. Box 1068 Blindern, 0316 Oslo, Norway.
| | - Øyvind Jacobsen
- Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, 0315 Oslo, Norway
| | - Sverre Arne Sande
- School of Pharmacy, University of Oslo, P.O. Box 1068 Blindern, 0316 Oslo, Norway
| | | | - Jo Klaveness
- Omegatri AS, P.O. Box 4849 Nydalen, 0422 Oslo, Norway; School of Pharmacy, University of Oslo, P.O. Box 1068 Blindern, 0316 Oslo, Norway
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López-Nicolás JM, Rodríguez-Bonilla P, García-Carmona F. Cyclodextrins and Antioxidants. Crit Rev Food Sci Nutr 2013; 54:251-76. [DOI: 10.1080/10408398.2011.582544] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Rodríguez-Bonilla P, Méndez-Cazorla L, López-Nicolás JM, García-Carmona F. Kinetic mechanism and product characterization of the enzymatic peroxidation of pterostilbene as model of the detoxification process of stilbene-type phytoalexins. PHYTOCHEMISTRY 2011; 72:100-108. [PMID: 21084102 DOI: 10.1016/j.phytochem.2010.10.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Revised: 10/14/2010] [Accepted: 10/18/2010] [Indexed: 05/30/2023]
Abstract
The enzymatic peroxidation of pterostilbene, a strong antifungal belonging to the stilbene family, by peroxidase (POX), is reported for the first time as a model of phytoalexin detoxification carried out by the enzymatic pool of pathogens. Kinetic characterization of the pterostilbene oxidation reaction pointed to an optimum pH of 7.0, at which value the thermal stability of POX was studied. Moreover, the data showed that pterostilbene inhibits POX activity at high concentrations of substrate. Several kinetic parameters, including V(max), K(m) and K(I), were calculated and values of 0.16ΔAbs min(-1), 14.61 μM, and 31.41 μM were reported. To understand the possible physiological role of this reaction in the phytoalexin detoxification process, the products of pterostilbene oxidation were identified using HPLC-MS and a radical-radical coupling reaction mechanism was proposed. Three main products with a high molecular weight and pronounced hydrophobicity were identified: pterostilbene cis dehydromer, pterostilbene trans dehydromer and pterostilbene open dimer. The dimeric structures of these molecules indicate that the pterostilbene oxidation reaction took place at the 4'-OH position of the hydroxystilbenic moieties and the three above mentioned dimeric products were found, due to the ability of electron-delocalized radicals to couple at various sites. Finally, the capacity of cyclodextrins (CDs) as starch model molecules in plants to complex both the substrate and the products of the oxidation reaction was evaluated. The inhibition process of POX activity was modified at high pterostilbene concentrations due to sequestering of the substrate reaction and to the different affinity of the reaction products for CDs.
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Affiliation(s)
- Pilar Rodríguez-Bonilla
- Department of Biochemistry and Molecular Biology-A, Faculty of Biology, University of Murcia, Murcia, Spain
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Physical characteristics of fish oil encapsulated by β-cyclodextrin using an aggregation method or polycaprolactone using an emulsion–diffusion method. Food Chem 2010. [DOI: 10.1016/j.foodchem.2009.09.052] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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López-Nicolás JM, García-Carmona F. Effect of hydroxypropyl-β-cyclodextrin on the aggregation of (E)-resveratrol in different protonation states of the guest molecule. Food Chem 2010. [DOI: 10.1016/j.foodchem.2009.05.039] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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14
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López-Nicolás JM, Rodríguez-Bonilla P, Méndez-Cazorla L, García-Carmona F. Physicochemical study of the complexation of pterostilbene by natural and modified cyclodextrins. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2009; 57:5294-5300. [PMID: 19459636 DOI: 10.1021/jf900285e] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
In this paper, the interaction between pterostilbene and cyclodextrins (CDs) is described for the first time using steady-state fluorescence. It was seen that pterostilbene forms a 1:1 complex with all of the natural (alpha-, beta-, and gamma-CDs) and modified (HP-beta-CD, methyl-beta-CD, and ethyl-beta-CD) CDs tested. Among natural CDs, the interaction of pterostilbene with beta-CD was the most efficient. However, all of the modified CDs showed higher complexation constants (K(F)) than beta-CD. The highest K(F) was found for HP-beta-CD (17520 +/- 981 M(-1)), in which its value showed a strong dependence upon pH in the region where the pterostilbene begins the deprotonation of its hydroxyl group. Moreover, the values of K(F) decreased as the system temperature increased. To obtain information on the mechanism of pterostilbene affinity for CD, the thermodynamic parameters of the complexation (DeltaH degrees , DeltaS degrees , and DeltaG degrees ) were studied. Finally, a comparison of the K(F) values obtained for three types of stilbenes revealed that both the stoichiometry and the K(F) values of the complex are dependent upon the structure of the guest molecule. While the trans-resveratrol-HP-beta-CD and pterostilbene-HP-beta-CD complexes showed a 1:1 stoichiometry with a higher K(F) value for the trans-resveratrol-HP-beta-CD complexes, trans-stilbene showed a 1:2 stoichiometry.
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Affiliation(s)
- José Manuel López-Nicolás
- Department of Biochemistry and Molecular Biology-A, Faculty of Biology, University of Murcia, Campus de Espinardo, Murcia, Spain.
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López-Nicolás JM, Pérez-Gilabert M, García-Carmona F. Effect of protonation and aggregation state of (E)-resveratrol on its hydroperoxidation by lipoxygenase. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2009; 57:4630-5. [PMID: 19371032 DOI: 10.1021/jf9001473] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The protonation and aggregation states of (E)-resveratrol were used as tools to investigate the kinetic properties of lipoxygenase (LOX). It was found that the deprotonation of the 4'-hydroxyl group at pH values higher than the pK(a1) of (E)-resveratrol produced an increase in the LOX activity, with an optimum pH of 8.5. Moreover, the results show how LOX activity is strongly affected by the aggregation state of (E)-resveratrol. When the enzyme uses monomers of (E)-resveratrol as substrate, LOX shows a Michaelian behavior and the K(m) value can be determined (44.39 microM). However, when (E)-resveratrol concentration is increased to values higher than the critical concentration determined by fluorescence methods (35 microM at pH 8.5), LOX shows strong inhibition. These results can be interpreted as a previously unreported aggregate-induced enzyme inhibition, which can be modified by the use of different modulators of the aggregation state of (E)-resveratrol, such as cyclodextrins or ethanol. Finally, when the reaction was kinetically characterized in the optimum conditions of both aggregation and protonation state, a typical induction period was observed, along with a dependence of the hydroperoxidation rate with the hydrogen peroxide concentration.
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Affiliation(s)
- José Manuel López-Nicolás
- Department of Biochemistry and Molecular Biology-A, Faculty of Biology, University of Murcia, Murcia, Spain.
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Avila-González R, Pérez-Gilabert M, López-López MA, García-Carmona F. Candida rugosa Lipase-Catalyzed Intramolecular O- to N-Transacylation of Butyryl Propranolol in the Presence of Cyclodextrins. Biotechnol Prog 2008; 21:338-42. [PMID: 15801768 DOI: 10.1021/bp0496272] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the present paper, a novel enzymatic reaction between (R,S)-O-butyryl propranolol (O-BP) and lipase from Candida rugosa in the presence of hydroxypropyl-beta-cyclodextrin (HP-beta-CD) is described. Under the used condition, lipase catalyzed the intramolecular transacylation of O-BP into N-butyryl propranolol (N-BP). Propranolol, the product of the expected hydrolysis reaction, was not detected in the reaction medium. A chiral analysis of the reaction product indicated that lipase showed a preference for (R)-O-butyryl propranolol since it first transformed the (R)-enantiomer and then the corresponding (S)-enantiomer. The influence of different reaction conditions on the initial rate is also studied.
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Affiliation(s)
- Rizette Avila-González
- Departamento de Bioquímica y Biología Molecular-A, Facultad de Biología, Universidad de Murcia, Campus de Espinardo, E-30100 Murcia, Spain
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Pérez-Gilabert M, García-Carmona F. Enhanced production of hydroperoxides by immobilized lipoxygenase in the presence of cyclodextrins. Biotechnol Prog 2005; 21:1742-7. [PMID: 16321060 DOI: 10.1021/bp050264v] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The advantages of the presence of cyclodextrins in a reaction catalyzed by immobilized lipoxygenase at neutral pH are reported for the first time. The steady-state rate in the presence of beta-cyclodextrins was seven times higher than in control experiments using the same concentration of linoleic acid; furthermore the percentage of substrate conversion (and product accumulation) obtained in the presence of beta-cyclodextrins was higher than in the control assays. The optimum concentration of free linoleic acid coincided with the critical micellar concentration for linoleic acid at neutral pH. The operational stability of the immobilized enzyme increased in the presence of beta-cyclodextins, while an increase in the percentage of 13-HPOD was also observed.
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Affiliation(s)
- Manuela Pérez-Gilabert
- Departamento de Bioquímica y Biología Molecular-A, Universidad de Murcia, Espinardo 30071, Spain.
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Avila-González R, Pérez-Gilabert M, García-Carmona F. Lipase-catalyzed preparation of S-propranolol in presence of hydroxypropyl β-cyclodextrins. J Biosci Bioeng 2005; 100:423-8. [PMID: 16310732 DOI: 10.1263/jbb.100.423] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2005] [Accepted: 06/24/2005] [Indexed: 11/17/2022]
Abstract
A simple method for the preparation of S-propranolol catalyzed by a Rhizopus niveus lipase in an aqueous medium is described. Hydroxypropyl-beta-cyclodextrin was used for the first time to increase the solubility of (R,S)-O-butyryl propranolol thus permitting the reaction to be carried out in water. The formation of an inclusion complex between (R,S)-O-butyryl propranolol and hydroxypropyl-beta-cyclodextrin was studied and a stoichiometry of 1:1 was determined. The influences of the hydroxypropyl-beta-cyclodextrin concentration, pH and percentage of ethanol on the enzymatic activity were also investigated. Under the conditions presented in this paper, values of ee(s) of 90% and E=48 were obtained.
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Affiliation(s)
- Rizette Avila-González
- Departamento de Bioquímica y Biología Molecular-A, Facultad de Veterinaria, Universidad de Murcia, Campus de Espinardo, E-30100 Murcia, Spain
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Irwin P, Gehring A, Tu SI, Chen CY. Blocking nonspecific adsorption of native food-borne microorganisms by immunomagnetic beads with ι-carrageenan. Carbohydr Res 2004; 339:613-21. [PMID: 15013398 DOI: 10.1016/j.carres.2003.10.033] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2003] [Accepted: 10/30/2003] [Indexed: 11/24/2022]
Abstract
We present herein the partitioning characteristics of anti-Salmonella and anti-Escherichia coli O157 immunomagnetic beads (IMB) with respect to the nonspecific adsorption of several nontarget food-borne organisms with and without an assortment of well-known blocking agents, such as casein, which have been shown to be useful in other immunochemical applications. We found several common food-borne organisms that strongly interacted with both types of IMB, especially with anti-Salmonella form (av DeltaG0=-20 +/- 4 kJ mol(-1)) even in the presence of casein [1% (w/v): DeltaG0=-18 +/- 3 kJ mol(-1); DeltaDeltaG0 approximately -2 kJ mol(-1)]. However, when one of the most problematic organisms (a native K12-like E. coli isolate; DeltaG0=-19 +/- 2 kJ mol(-1)) was tested for nonspecific binding in the presence of iota-carrageenan (0.03-0.05%), there was an average decline of ca. 90% in the equilibrium capture efficiency xi (DeltaG0=-11 +/- 4 kJ mol(-1); DeltaDeltaG0 approximately -8 kJ mol(-1)). Other anionic polysaccharides (0.1% kappa-carrageenan and polygalacturonic acid) had no significant effect (av DeltaG0=-19 +/- 1 kJ mol(-1); DeltaDeltaG0 approximately 0 kJ mol(-1)). Varying iota-carrageenan from 0% to 0.02% resulted in xi significantly diminishing from 0.69 (e.g., 69% of the cells captured; DeltaG0=-19 +/- 3 kJ mol(-1)) to 0.05 (DeltaG0=-11 +/- 2 kJ mol(-1); DeltaDeltaG0 approximately -9 kJ mol(-1)) at about 0.03% iota-carrageenan where xi leveled off. An optimum blocking ability was achieved with 0.04% iota-carrageenan suspended in 100 mM phosphate buffer. We also demonstrated that the utilization of iota-carrageenan as a blocking agent causes no great loss in the IMBs capture efficiency with respect to the capture of its target organisms, various salmonellae.
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Affiliation(s)
- Peter Irwin
- Microbial Biophysics and Residue Chemistry, ARS, Eastern Regional Research Center, US Department of Agriculture, 600 E Mermaid Lane, Wyndmoor, PA 19038, USA.
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López-Nicolás JM, Bru R, García-Carmona F. Kinetic characteristics of the enzymatic conversion in presence of cyclodextrins: study of the oxidation of polyunsaturated fatty acids by lipoxygenase. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1347:140-50. [PMID: 9295158 DOI: 10.1016/s0005-2760(97)00061-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The capability of cyclodextrins (CDs) to greatly enhance the solubility in water of poorly water-soluble substances makes them an ideal alternative system for studying the expression of enzyme activity with such substrates in aqueous solution. In order to evaluate the behaviour of the enzymes in presence of CDs a study of the lipoxygenase (LOX)-catalyzed oxidation of polyunsaturated fatty acids (PUFA) as model reaction has been carried out. This was done by using LOX from two different sources (soybean and potato tuber), at two pH values (6.3 and 9.0), with two substrates (linoleic acid and arachidonic acid) and three types of CD (beta-CD, methyl-beta-CD and monoglucosyl-beta-CD). PUFA have been shown to form inclusion complexes of 1:2 stoichiometry which are in equilibrium with free PUFA and free CD, thus complexation is governed by two equilibrium constants, K1 and K2 (J.M. López-Nicolás et al., Biochem. J. 308 (1995) 151-154; R. Bru et al., Colloids Surf. 97 (1995) 263-269). For the oxidation of PUFA by LOX in the presence of beta-CD we propose a model in which free PUFA is the only effective substrate, thus the oxidation of the complexed substrate requires the previous dissociation of the complex. The equilibrium constants of complex formation are determined by both a physico-chemical and an enzymatic method. In spite of giving quite similar results, the second was proven to be more accurate so it was employed in further studies. CD was shown to slow down the reaction rate of LOX, specifically due to the increase of Km, Vmax remaining unchanged. That apparent inhibition is due to removal of effective (free) substrate in the form of inclusion complexes. This 'sequestered' substrate can, however, be converted since it is in equilibrium with the free. The feasibility of realizing a CD-mediated accurate control over the conversion rate is demonstrated in the experiment called 'cyclodextrin assay' in which the concentration of the free substrate is calculated by using the equilibrium constants of complex formation and setting the initial concentrations of total substrate and total CD. From the observation of the reaction progress curves in the conditions of the CD assay, we have studied some characteristic parameters of the oxidation of PUFA by LOX in this new medium, such as enzymatic activity, duration of linear product accumulation and the lag phase.
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Affiliation(s)
- J M López-Nicolás
- Departamento de Bioquimica y Biología Molecular A, Facultad de Biología, Universidad de Murcia, Campus de Espinardo, Spain
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