Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 67
Filter
Add more filters











Publication year range
1.
Nano Lett ; 2024 Oct 04.
Article in English | MEDLINE | ID: mdl-39365276

ABSTRACT

Atomically precise Pd-thiolate clusters are well-known for their well-defined structures and diverse applications involving catalysis, sensors, and biomedicine. While many of these clusters have been studied, their molecular structures typically feature a tiara-like arrangement. In this study, we present the first example of a non-tiara-like Pd-thiolate cluster: the octahedral Pd6(SC6H11)12 (denoted as Pd6-Oct). The composition and geometric structure of the cluster were characterized using electrospray ionization mass spectrometry (ESI-MS) together with single-crystal X-ray diffraction (SXRD). Despite having a similar chemical composition to tiara-like Pd6(SC2H4Ph)12 (denoted as Pd6-Tia), Pd6-Oct exhibits a distinctly different geometric structure. Additionally, UV-vis-NIR absorption spectroscopy combined with quantum chemical calculations provided valuable insights into the electronic structures of these clusters. The excited-state dynamics, host-guest chemistry, and the catalytic properties of Pd6-Oct and Pd6-Tia were examined to compare their structure-property relationships. This research represents significant advances in the synthesis and understanding of structure-property correlations in Pd-thiolate clusters.

2.
ChemistryOpen ; : e202400071, 2024 Sep 24.
Article in English | MEDLINE | ID: mdl-39318071

ABSTRACT

An open-chain iron pyridine-NHC framework is expanded utilizing a benzimidazole moiety to deepen the understanding of the impact of electronic variations on iron NHC epoxidation catalysts, especially regarding the stability. The thereby newly obtained iron(II) NHC complex is characterized and employed in olefin epoxidation. It is remarkably temperature tolerant and achieves a TOF of ca. 10 000 h-1 and TON of ca. 700 at 60 °C in the presence of the Lewis acid Sc(OTf)3, displaying equal stability, but lower activity than the unmodified iron pyridine-NHC (pre-)catalyst. In addition, a synthetic approach towards another ligand containing 2-imidazoline units is described but formylation as well as hydrolysis hamper its successful synthesis.

3.
Article in English | MEDLINE | ID: mdl-39325292

ABSTRACT

Aspergillus oryzae is an ideal cell factory for protein expression with powerful protein processing and secretion capabilities. The current study aimed to explore the homologous expression of A. oryzae lipase AOL (GenBank: KP975533) by constructing an auxotrophic A. oryzae △pyrG△nptB and subsequently characterizing the immobilization and catalytic properties of recombinant lipase. Initially, the pyrG gene knocked out in wild-type A. oryzae by homologous recombination, followed by the creation of a uridine/uracil auxotroph transformation. Through this system, the protease gene nptB was precisely knocked out, leading to a substantial decrease in extracellular (39.04%) and intracellular (90.07%) protease activity. The A. oryzae △nptB△pyrG strain was used as host for homologous expression of lipase AOL. After transformation of linearized lipase-expression cassette, the engineered A. oryzae AOL-8 was screened out with the lipase gene copy number of 14, exhibiting extracellular and intracellular lipase activities of 1.75 U/mL and 46.4 U/g, respectively. Subsequently, the production and immobilization of the recombinant lipase, via physical adsorption on macroporous resin XRZ04B, were achieved through submerged fermentation of the AOL-8 strain. The results of esterification catalytic properties of immobilized recombinant lipase indicated that the lipase exhibited optimal catalytic activity with lauric acid and methanol as substrates, a reaction temperature of 35 °C, and n-hexane as the preferred solvent medium; its highest conversion rate can reach at 72.3%.

4.
Pharmaceuticals (Basel) ; 17(9)2024 Aug 23.
Article in English | MEDLINE | ID: mdl-39338271

ABSTRACT

Increasing levels of reactive oxygen species generate oxidative stress in the human body that can lead to various medical conditions. The use of nanomaterials exhibiting antioxidant properties may prevent these effects. The biological synthesis of metallic nanoparticles using plant extracts with antioxidant properties can offer benefits due to their active compounds. The used extracts contained reducing and stabilizing agents, which were shown to be transferred onto the gold nanoparticles, functionalizing them. Herin, we report a gold nanoparticle synthesis by eco-friendly biological methods (b-AuNPs) using extracts of sea buckthorn, lavender, walnuts, and grapes, obtained through ultrasound-assisted extraction and pressure-enhanced extraction. The obtained b-AuNPs were characterized by UV-Vis and FTIR spectroscopies and visualized using transmission electron microscopy. The catalytic and scavenging effect of the b-AuNPs towards H2O2 (as reactive oxygen species) was evaluated electrochemically, highlighting the protective behavior of b-AuNPs towards lipid peroxidation. All experiments demonstrated the stability and reproducibility of prepared b-AuNPs with enhanced antioxidant and catalytic properties, opening a new perspective for their use in biomedical applications.

5.
J Fungi (Basel) ; 10(8)2024 Aug 08.
Article in English | MEDLINE | ID: mdl-39194885

ABSTRACT

Laccases are important and valuable enzymes with a great potential for biotechnological applications. In this study, two novel laccases, LacHU1 and LacHU2, from Alternaria sp. HU have been purified and characterized. The molecular mass of each isoenzyme was ~66 kDa. LacHU1 laccases was yellow and had no typical blue oxidase spectra and LacHU2 had a blue color and characteristic absorption spectra. The catalytic efficiency of LacHU1 for most substrates was higher than that of LacHU2 laccase. Both isoenzymes effectively oxidize flavonoids. Alternaria sp. laccases were successfully immobilized on magnetic nanoparticles. The thermostability of immobilized laccases increased and optimal pH shifted to more alkaline compared to the free laccases. Potential applications of laccases from Alternaria sp. HU are in the oxidation of flavonoids in cotton or in water treatment processes.

6.
Anal Bioanal Chem ; 2024 Jul 16.
Article in English | MEDLINE | ID: mdl-39009769

ABSTRACT

Nanomaterials with enzyme-like properties are known as 'nanozymes'. Nanozymes are preferred over natural enzymes due to their nanoscale characteristics and ease of tailoring of their physicochemical properties such as size, structure, composition, surface chemistry, crystal planes, oxygen vacancy, and surface valence state. Interestingly, nanozymes can be precisely controlled to improve their catalytic ability, stability, and specificity which is unattainable by natural enzymes. Therefore, tailor-made nanozymes are being favored over natural enzymes for a range of potential applications and better prospects. In this context, metal oxide nanoparticles with nanozyme-mimicking characteristics are exclusively being used in biomedical sectors and opening new avenues for future nanomedicine. Realising the importance of this emerging area, here, we discuss the mechanistic actions of metal oxide nanozymes along with their key characteristics which affect their enzymatic actions. Further, in this critical review, the recent progress towards the development of point-of-care (POC) diagnostic devices, cancer therapy, drug delivery, advanced antimicrobials/antibiofilm, dental caries, neurodegenerative diseases, and wound healing potential of metal oxide nanozymes is deliberated. The advantages of employing metal oxide nanozymes, their potential limitations in terms of nanotoxicity, and possible prospects for biomedical applications are also discussed with future recommendations.

7.
Colloids Surf B Biointerfaces ; 235: 113764, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38301428

ABSTRACT

Development of immobilized lipase with excellent catalytic performance and low cost is the major challenge for large-scale industrial applications. In this study, green renewable microcrystalline cellulose (MCC) that was hydrophobically modified with D-alanine (Ala) or L-lysine (Lys) was used for immobilizing Candida antarctica lipase B (CALB). The improved catalytic properties were investigated by experimental and computational methods. CALB immobilized on MCC-Ala with higher hydrophobicity showed better catalytic activity than CALB@MCC-Lys because the increased flexibility of the lid region of CALB@MCC-Ala favored the formation of open conformation. Additionally, the low root mean square deviation and the high ß-sheet and α-helix contents of CALB@MCC-Ala indicated that the structure became more stable, leading to a significantly enhanced stability (54.80% and 90.90% relative activity at 70 °C and pH 9.0, respectively) and good reusability (48.92% activity after 5 cycles). This study provides a promising avenue to develop immobilized lipase with high catalytic properties for industry applications.


Subject(s)
Amino Acids , Cellulose , Enzymes, Immobilized , Enzymes, Immobilized/chemistry , Candida/metabolism , Lipase/chemistry , Fungal Proteins/chemistry , Alanine , Lysine
8.
Biochemistry (Mosc) ; 88(9): 1378-1389, 2023 Sep.
Article in English | MEDLINE | ID: mdl-37770404

ABSTRACT

Previously, the gene of formate dehydrogenase (FDH, EC 1.2.1.2) from the thermotolerant methylotrophic yeast Ogataea parapolymorpha DL 1 (OpaFDH) was cloned in our laboratory. Recombinant enzyme with additional glycine amino acid residue (OpaFDH_GK) was obtained in Escherichia coli cells in active and soluble form with a yield of more than 1 g per liter of the medium. In the present work, a detailed comparison of this enzyme with FDHs from other sources was carried out. Among eukaryotic formate dehydrogenases, OpaFDH has the highest thermal stability. To elucidate effect of N-terminal residue on the properties of the enzyme, OpaFDH_K (identical to natural) and OpaFDH_AK variants containing an additional Ala residue at the N-terminus were also obtained. It was shown that addition of an Ala residue to the N-terminus reduces four-fold the rate constant of thermal inactivation compared with the addition of a Gly residue. Addition of six more histidine residues to the N-terminus of OpaFDH_AK leads to acceleration of purification, practically does not affect kinetic parameters, but somewhat reduces thermal stability, which, however, can be restored to the level of OpaFDH_AK stability by adding 0.5 M NaCl.

9.
World J Microbiol Biotechnol ; 39(7): 191, 2023 May 10.
Article in English | MEDLINE | ID: mdl-37160824

ABSTRACT

α-L-rhamnosidase [EC 3.2.1.40] belongs to glycoside hydrolase (GH) families (GH13, GH78, and GH106 families) in the carbohydrate-active enzymes (CAZy) database, which specifically hydrolyzes the non-reducing end of α-L-rhamnose. Αccording to the sites of catalytic hydrolysis, α-L-rhamnosidase can be divided into α-1, 2-rhamnosidase, α-1, 3-rhamnosidase, α-1, 4-rhamnosidase and α-1, 6-rhamnosidase. α-L-rhamnosidase is an important enzyme for various biotechnological applications, especially in food, beverage, and pharmaceutical industries. α-L-rhamnosidase has a wide range of sources and is commonly found in animals, plants, and microorganisms, and its microbial source includes a variety of bacteria, molds and yeasts (such as Lactobacillus sp., Aspergillus sp., Pichia angusta and Saccharomyces cerevisiae). In recent years, a series of advances have been achieved in various aspects of α-validates the above-described-rhamnosidase research. A number of α-L-rhamnosidases have been successfully recombinant expressed in prokaryotic systems as well as eukaryotic systems which involve Pichia pastoris, Saccharomyces cerevisiae and Aspergillus niger, and the catalytic properties of the recombinant enzymes have been improved by enzyme modification techniques. In this review, the sources and production methods, general and catalytic properties and biotechnological applications of α-L-rhamnosidase in different fields are summarized and discussed, concluding with the directions for further in-depth research on α-L-rhamnosidase.


Subject(s)
Biocatalysis , Biotechnology , Drug Industry , Food Industry , Glycoside Hydrolases , Industrial Microbiology , Animals , Humans , Glycoside Hydrolases/biosynthesis , Glycoside Hydrolases/chemistry , Glycoside Hydrolases/genetics , Glycoside Hydrolases/metabolism , Recombinant Proteins/biosynthesis , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Recombinant Proteins/metabolism
10.
Int J Mol Sci ; 24(5)2023 Feb 22.
Article in English | MEDLINE | ID: mdl-36901801

ABSTRACT

Zeolitic imidazolate frameworks (ZIFs) have been extensively examined for their potential in acid-base catalysis. Many studies have demonstrated that ZIFs possess unique structural and physicochemical properties that allow them to demonstrate high activity and yield products with high selectivity. Herein, we highlight the nature of ZIFs in terms of their chemical formulation and the textural, acid-base, and morphological properties that strongly affect their catalytic performance. Our primary focus is the application of spectroscopic methods as instruments for analyzing the nature of active sites because these methods can allow an understanding of unusual catalytic behavior from the perspective of the structure-property-activity relationship. We examine several reactions, such as condensation reactions (the Knoevenagel condensation and Friedländer reactions), the cycloaddition of CO2 to epoxides, the synthesis of propylene glycol methyl ether from propylene oxide and methanol, and the cascade redox condensation of 2-nitroanilines with benzylamines. These examples illustrate the broad range of potentially promising applications of Zn-ZIFs as heterogeneous catalysts.


Subject(s)
Zeolites , Zeolites/chemistry , Imidazoles/chemistry , Catalysis , Structure-Activity Relationship
11.
Materials (Basel) ; 16(2)2023 Jan 10.
Article in English | MEDLINE | ID: mdl-36676395

ABSTRACT

This publication presents the synthesis of core-shell nanoparticles, where the core was Ni, and the shell was a Ag-Ni nano alloy. The synthesis was based on the reduction of Ni and Ag ions with sodium borohydride in the presence of trisodium citrate as a stabilizer. In order to determine the phase composition of the obtained nanoparticles, an XRD study was performed, and in order to identify the oxidation states of the nanoparticle components, an XPS spectroscopic study was performed. The composition and shape of the particles were determined using the HR-TEM EDS test. The obtained nanoparticles had a size of 11 nm. The research on catalytic properties was carried out in the model methylene blue reduction system. The investigation of the catalytic activity of colloids was carried out with the use of UV-Vis spectrophotometry. The Ag-Ni alloy was about ten times more active than were pure silver nanoparticles of a similar size.

12.
Int J Mol Sci ; 23(17)2022 Sep 01.
Article in English | MEDLINE | ID: mdl-36077332

ABSTRACT

Processes involving lipases in obtaining active pharmaceutical ingredients (APIs) are crucial to increase the sustainability of the industry. Despite their lower production cost, microbial lipases are striking for their versatile catalyzing reactions beyond their physiological role. In the context of taking advantage of microbial lipases in reactions for the synthesis of API building blocks, this review focuses on: (i) the structural origins of the catalytic properties of microbial lipases, including the results of techniques such as single particle monitoring (SPT) and the description of its selectivity beyond the Kazlauskas rule as the "Mirror-Image Packing" or the "Key Region(s) rule influencing enantioselectivity" (KRIE); (ii) immobilization methods given the conferred operative advantages in industrial applications and their modulating capacity of lipase properties; and (iii) a comprehensive description of microbial lipases use as a conventional or promiscuous catalyst in key reactions in the organic synthesis (Knoevenagel condensation, Morita-Baylis-Hillman (MBH) reactions, Markovnikov additions, Baeyer-Villiger oxidation, racemization, among others). Finally, this review will also focus on a research perspective necessary to increase microbial lipases application development towards a greener industry.


Subject(s)
Industry , Lipase , Catalysis , Chemistry Techniques, Synthetic , Lipase/chemistry , Pharmaceutical Preparations
13.
Int J Biol Macromol ; 209(Pt A): 912-922, 2022 Jun 01.
Article in English | MEDLINE | ID: mdl-35447260

ABSTRACT

We report a facile microwave-assisted synthesis of palladium nanoparticles (PdNPs) using Bael gum (BG) and it's carboxymethylated (CMBG) derivative. The prepared nanoparticles (BG@PdNPs and CMBG@PdNPs) were evaluated for antibacterial and catalytic activity in the reduction of organic dye pollutants. The developed synthetic method is simple, low cost and eco-friendly, wherein the process requires no additional reducing or capping agents. The CMBG was prepared via etherification reaction between BG and monochloroacetic acid using Williamson synthesis method. The PdNPs were synthesized using BG and CMBG as stabilizers and reducing agents. The PdNPs were found to be well dispersed spherical, with the crystalline size of the order of 7-21 nm. The results showed that the CMBG@PdNPs were smaller in size (7 ± 2 nm) than those capped with BG@PdNPs (10 ± 2 nm). The catalytic ability of CMBG@PdNPs was examined for the reduction of Methyl Orange (MO), Methyl Red(MR), and Rhodamine-B (RhB) in the presence of NaBH4. The results showed that CMBG@PdNPs exhibited a higher catalytic ability than BG@PdNPs. Moreover, it was found that CMBG@PdNPs served several times as a retrievable and reusable catalyst which is stable even after six cycles of reaction. The CMBG@PdNPs and BG@PdNPs showed excellent antibacterial activity. The results indicate that CMBG@PdNPs have greater potential application as a catalyst in the reduction of organic pollutants and antibacterial activity.


Subject(s)
Environmental Pollutants , Metal Nanoparticles , Anti-Bacterial Agents/pharmacology , Catalysis , Metal Nanoparticles/chemistry , Palladium/chemistry
14.
Acta Naturae ; 14(1): 82-91, 2022.
Article in English | MEDLINE | ID: mdl-35441051

ABSTRACT

Formate dehydrogenase from Pseudomonas sp. 101 bacterium (PseFDH, EC 1.2.1.2) is a research model for the elucidation of the catalytic mechanism of 2-oxyacid D-specific dehydrogenases enzyme superfamily. The enzyme is actively used for regeneration of the reduced form of NAD(P)H in chiral synthesis with oxidoreductases. A multi-point mutant PseFDH SM4S with an improved thermal and chemical stability has been prepared earlier in this laboratory. To further improve the properties of the mutant, additional single-point replacements have been introduced to generate five new PseFDH mutants. All new enzymes have been highly purified, and their kinetic properties and thermal stability studied using analysis of thermal inactivation kinetics and differential scanning calorimetry. The E170D amino acid change in PseFDH SM4S shows an increase in thermal stability 1.76- and 10-fold compared to the starting mutant and the wild-type enzyme, respectively.

15.
Angew Chem Int Ed Engl ; 61(11): e202116965, 2022 Mar 07.
Article in English | MEDLINE | ID: mdl-35014157

ABSTRACT

We report the structures, stability and catalysis properties of two Ag21 nanoclusters, namely [Ag21 (H2 BTCA)3 (O2 PPh2 )6 ]SbF6 (1) and [Ag21 (C≡CC6 H3 -3,5-R2 )6 (O2 PPh2 )10 ]SbF6 (2) (H4 BTCA=p-tert-butylthiacalix[4]arene, R=OMe). Both Ag21 structures possess an identical icosahedral kernel that is surrounded by eight peripheral Ag atoms. Single-crystal structural analysis and ESI-MS revealed that 1 is an 8-electron cluster and 2 has four free electrons. Theoretical results show that the P-symmetry orbitals are found as HOMO-1 and HOMO states in 1, and the frontier unoccupied molecular orbitals (LUMO, LUMO+1 and LUMO+2) show D-character, indicating 1 is a superatomic cluster with an electronically closed shell 1S2 1P6 , while 2 has an incomplete shell configuration 1S2 1P2 . These two Ag21 clusters show superior stability under ambient conditions, and 1 is robust even at 90 °C in toluene and under oxidative conditions (30 % H2 O2 ). Significantly, 2 exhibits much higher activity than 1 as catalyst in the reduction of 4-nitrophenol. This work demonstrates that ligands can influence the electronic structures of silver clusters, and further affect their stability and catalytic performance.

16.
Bioresour Bioprocess ; 9(1): 129, 2022 Dec 16.
Article in English | MEDLINE | ID: mdl-38647758

ABSTRACT

Modified xanthan produced by xanthan lyase has broad application prospects in the food industry. However, the catalytic performance of xanthan lyase still needs to be improved through rational design. To address this problem, in this work, the glycosylation and its influences on the catalytic performance of a xanthan lyase (EcXly), which was heterologously expressed in Escherichia coli, were reported. Liquid chromatography coupled to tandem mass spectrometry analysis revealed that the N599 site of EcXly was modified by a single N-glycan chain. Based on sequence alignment and three-dimensional structure prediction, it could be deduced that the N599 site was located in the catalytic domain of EcXly and in close proximity to the catalytic residues. After site-directed mutagenesis of N599 with alanine, aspartic acid and glycine, respectively, the EcXly and its mutants were characterized and compared. The results demonstrated that elimination of the N-glycosylation had diminished the specific activity, pH stability, and substrate affinity of EcXly. Fluorescence spectra further revealed that the glycosylation could significantly affect the overall tertiary structure of EcXly. Therefore, in prokaryotic hosts, the N-glycosylation could influence the catalytic performance of the enzyme by changing its structure. To the best of our knowledge, this is the first report about the post-translational modification of xanthan lyase in prokaryotes. Overall, our work enriched research on the role of glycan chains in the functional performance of proteins expressed in prokaryotes and should be valuable for the rational design of xanthan lyase to produce modified xanthan for industrial application.

17.
Molecules ; 26(21)2021 Oct 21.
Article in English | MEDLINE | ID: mdl-34770772

ABSTRACT

Methyl-substituted 8-hydroxyquinolines (Hquin) were successfully used to synthetize five-coordinated oxovanadium(IV) complexes: [VO(2,6-(Me)2-quin)2] (1), [VO(2,5-(Me)2-quin)2] (2) and [VO(2-Me-quin)2] (3). Complexes 1-3 demonstrated high catalytic activity in the oxidation of hydrocarbons with H2O2 in acetonitrile at 50 °C, in the presence of 2-pyrazinecarboxylic acid (PCA) as a cocatalyst. The maximum yield of cyclohexane oxidation products attained was 48%, which is high in the case of the oxidation of saturated hydrocarbons. The reaction leads to the formation of a mixture of cyclohexyl hydroperoxide, cyclohexanol and cyclohexanone. When triphenylphosphine is added, cyclohexyl hydroperoxide is completely converted to cyclohexanol. Consideration of the regio- and bond-selectivity in the oxidation of n-heptane and methylcyclohexane, respectively, indicates that the oxidation proceeds with the participation of free hydroxyl radicals. The complexes show moderate activity in the oxidation of alcohols. Complexes 1 and 2 reduce the viability of colorectal (HCT116) and ovarian (A2780) carcinoma cell lines and of normal dermal fibroblasts without showing a specific selectivity for cancer cell lines. Complex 3 on the other hand, shows a higher cytotoxicity in a colorectal carcinoma cell line (HCT116), a lower cytotoxicity towards normal dermal fibroblasts and no effect in an ovarian carcinoma cell line (order of magnitude HCT116 > fibroblasts > A2780).


Subject(s)
Coordination Complexes/chemistry , Coordination Complexes/pharmacology , Oxyquinoline/chemistry , Vanadium/chemistry , Alcohols/chemistry , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Catalysis , Cell Line, Tumor , Cell Survival/drug effects , Chemistry Techniques, Synthetic , Coordination Complexes/chemical synthesis , Humans , Hydrocarbons/chemistry , Inhibitory Concentration 50 , Models, Molecular , Molecular Structure , Oxidation-Reduction , Peroxides/chemistry , Reactive Oxygen Species/metabolism , Spectrum Analysis
18.
Appl Biochem Biotechnol ; 193(7): 2225-2244, 2021 Jul.
Article in English | MEDLINE | ID: mdl-33686629

ABSTRACT

Tannase from Aspergillus niger NL112 was purified 5.1-fold with a yield of 50.44% via ultrafiltration, DEAE-Sepharose Fast Flow column chromatography, and Sephadex G-100 column chromatography. The molecular weight of the purified tannase was estimated as 45 kDa. The optimum temperature and pH for its activity were 45 °C and 5.0, respectively. The results of circular dichroism, FT-IR (Fourier transform infrared) spectroscopy, and fluorescence spectra indicated that high temperature could lead to the change of tannase secondary and tertiary structures. Tannase had a greater affinity for tannic acid at 40 °C with a Km value of 2.12 mM and the greatest efficiency hydrolysis (Kcat/Km) at 45 °C. The rate of inactivation (k) increased with the increase of temperature and the half-life (t1/2) gradually decreased. It was found to be 1.0 of the temperature quotient (Q10) value for tannic acid hydrolysis by tannase. The thermodynamic parameters of the interaction system were calculated at various temperatures. The positive enthalpy (ΔH) values and decreasing ΔH values with the increase of temperature indicated that the hydrolysis of tannase was an endothermic process. Our results indicated that elevated temperature could change the tertiary structure of tannase and reduce its thermostability, which caused a gradual decrease of tannase activity with an increase in temperature.


Subject(s)
Aspergillus niger/enzymology , Carboxylic Ester Hydrolases/chemistry , Fungal Proteins/chemistry , Enzyme Stability , Hot Temperature , Protein Domains
19.
Article in English | MEDLINE | ID: mdl-33412298

ABSTRACT

In order to establish the role of diet on the induction and catalytic properties of glutathione transferase (GST) in insects, variegated grasshopper (Zonocerus variegatus) was exposed to different food plants separately for 30 days and the properties of the induced enzyme were then investigated. Insects fed on cassava (M. esculenta) leaves had the highest GST induction followed by insects fed on bitter leaf (V. amygdalina). Z. variegatus that fed in the wild on different food plants had the least suggesting that allelochemicals in the food plants have a compensatory toxicity-alleviating actions on one another. 1-Chloro-2,4-dinitrobenzene (CDNB) was the best substrate for all the induced GST however, the mode of binding of the substrate to the induced enzyme was not the same. GST from M. esculenta-fed insect showed ping-pong kinetic mechanism whereas GSTs from V. amygdalina and T. procumbens-fed insects showed random sequential mode of substrate binding. Catalytic efficiency (kcat/Km) of GST from M. esculenta-fed insects was 3-8-fold higher than other induced enzymes. Commercial insecticides- cypermethrin and lindane had an inhibition constant, Ki, of 0.13±0.004 mM and 0.68±0.09 mM, respectively, suggesting that the concentration as used in the field (0.03 mM for cypermethrin and 0.3 mM for lindane) would have little effect on the insect's GST. The study concluded that higher GST activity are induced in insects that fed on monotonous diets than those that fed on various food plants. Hindgut appears to be the primary organ of detoxication. The catalytic properties of the induced enzymes are different from one another.


Subject(s)
Enzyme Induction/drug effects , Glutathione Transferase/metabolism , Glycosides/pharmacology , Grasshoppers/enzymology , Plants/classification , Animal Feed , Animals , Glutathione Transferase/genetics , Glycosides/chemistry , Plant Leaves/chemistry
20.
J Food Biochem ; 45(2): e13617, 2021 02.
Article in English | MEDLINE | ID: mdl-33491200

ABSTRACT

Lipoxygenase (LOX, E.C. 1.13.11.12), among its various roles, catalyzes the degradation of polyunsaturated fatty acids and it is considered to be one of the main causes of undesirable off-flavor developments in legumes. The role of LOX in postharvest physiology is particularly significant in seeds with high values of lipoxygenase and linoleic acid levels. This research aimed to study the biochemical properties of the LOX extracted from green pea (Pisum sativum L. var. Léda, Zeusz, Zsuzsi), dry pea (Pisum sativum L. var. Hanka, Irina, Lutra), and lentil (Lens culinaris L., var. Pinklevi, Rézi, Castelluccio), using linoleic acid as a substrate. The raw extracts showed different catalytic properties, with dry pea (var. Irina) that expressed the highest LOX activity, while lentil (var. Pinklevi) expressed the lowest activity. To complete the biochemical characterization of the crude LOX extracts, their optimal pH and temperature were also examined. The highest value of lipoxygenase activity in the pH range 6-7 was measured in all legumes. The optimal temperature for all extracts fell within the range of 30-60°C given the nutritional importance of legumes. This study will serve as a basis for further detailed investigation of the legumes LOX activity and its roles in food products related to legumes. PRACTICAL APPLICATIONS: This study investigated the biochemical properties of lipoxygenase (LOX) extracted from different varieties of lentil and pea, the two important leguminous crops serving as the main protein source for the population of humans worldwide. The biochemical properties of LOX extracted from legumes showed large differences in terms of kinetic properties. The results of this study revealed that the use of lipoxygenase can be a suitable index for managing stabilization techniques of lentil and pea, in order to inhibit the lipid oxidation in grain legume without compromising its nutritional value.


Subject(s)
Fabaceae , Lens Plant , Humans , Lipoxygenase , Pisum sativum , Seeds
SELECTION OF CITATIONS
SEARCH DETAIL