Browsing by Author "Basi, Zehra"

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Determination of Malation, Methidathion, and Chlorpyrifos Ethyl Pesticides Using Acetylcholinesterase Biosensor Based on Nafion/Ag@rgo-nh2 Nanocomposites
(Pergamon-elsevier Science Ltd, 2017) Guler, Muhammet; Turkoglu, Vedat; Basi, Zehra
Herein, a facile electrochemical acetylcholinesterase (EC 3.1.1.7; AChE) biosensor based on nafion (NA) and Ag nanoparticles supported on amine functionalized reduced graphene oxide (rGO-NH2) was developed. The Ag@rGO-NH2 nanocomposite was characterized using Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and X-ray diffraction (XRD). After being optimized, the biosensor exhibited excellent electrochemical response to the oxidation of thiocholine, the hydrolysis product of acetylthiocholine chloride (ATCl) catalyzed by AChE. An apparent Michealis-Menten value of 20.5 mu M was obtained. Under optimized conductions, the biosensor detected malation, methidathion, and chlorpyrifos ethyl in the linear range from 0.0063 to 0.077 mu g/mL, from 0.012 to 0.105 mu g/mL, and from 0.021 to 0.122 mu g/mL, respectively. The detection limit (LoD) was 4.5 ng/mL for malation, 9.5 ng/mL for methidathion, and 14 ng/mL for chlorpyrifos ethyl. Also, the NA/Ag@rGO-NH2/ AChE/GCE biosensor showed god sensitivity, stability and repeatability, which provides a promising tool for the detection of organophosphate pesticides. (C) 2017 Elsevier Ltd. All rights reserved.
Electrochemical Determination of Fluoroquinolone Antibiotic Norfloxacin in the Presence of Anionic Surfactant Using the Anodically Pretreated Boron-Doped Diamond Electrode
(Wiley-v C H verlag Gmbh, 2020) Karahan, Fatih; Basi, Zehra; Keskin, Ertugrul; Pinar, Pinar Talay; Yardim, Yavuz; Senturk, Zuhre
In this article, a simple, fast and inexpensive methodology has been developed for the determination of fluoroquinolone class antibiotic norfloxacin (NFX) in anionic surfactant media (sodium dodecyl sulphate, SDS) using an anodically pretreated boron-doped diamond (APT-BDD) electrode. Cyclic voltammetric studies showed that the NFX gave an irreversible and adsorption controlled anodic oxidation signal at a potential of about +1.32 V on the APT-BDD electrode. The effects of parameters such as the electrode pre-treatment procedure, SDS concentration, and instrumental variables on the electrochemical sensitivity of NFX were evaluated. Under optimized conditions, the linearity was achieved in the range of 0.05 to 4.0 mu g mL(-1) (1.57x10(-7)-1.25x10(-5) mol L-1), with a detection limit of 0.013 mu g mL(-1) (4.07x10(-8) mol L-1) by using square-wave adsorptive stripping voltammetry (SW-AdSV). The feasibility of the developed approach for the quantification of NFX in urine samples was tested.
In Vitro Determination of 6pgd Enzyme Activity Purified From Lake Van Fish (Chalcalburnus Tarichii Pallas, 1811) Liver Exposed To Pesticides
(Springer, 2013) Guler, Muhammet; Kivanc, M. Riza; Turkoglu, Vedat; Basi, Zehra; Kivrak, Hilal
In the present study, the effect of methidathion, cypermethrin, and deltamethrin pesticides on Lake Van fish (Chalcalburnus tarichii Pallas, 1811) liver 6-phosphogluconate dehydrogenase enzyme activity was investigated due to the fact that these pesticides are extensively used to improve agricultural productivity in the Van region. 2',5'-ADP Sepharose 4B affinity chromatography was used to purify 6-phosphogluconate dehydrogenase enzyme from fish liver and SDS-PAGE technique was used to control the purity of this enzyme. The in vitro effect of methidathion, cypermethrin, and deltamethrin pesticides on the enzyme activity was investigated. The enzyme was purified 1,050-fold with specific activity of 27.04 EU/mg protein. Moreover, K-i constants of methidathion, cypermethrin, and deltamethrin were to be 3.294 +/- A 0.215, 0.718 +/- A 0.095, and 0.084 +/- A 0.009 mM respectively. The IC50 value were estimated as 9.95 x 10(-5) +/- A 0.1844 x 10(-5) mM for methidathion, 1.01 x 10(-4) +/- A 0.01413 x 10(-4) mM for cypermethrin, and 4.43 x 10(-6) +/- A 0.05653 x 10(-6) mM for deltamethrin. In conclusion, deltamethrin inhibits the enzyme activity more than methidathion and cypermethrin.
In Vitro Effect of Ethyl Acetate, Butanol and Water Extracts of Juniperus Excelsa Bieb. on Angiotensin-Converting Enzyme Purified From Human Plasma
(Springer international Publishing Ag, 2019) Basi, Zehra; Turkoglu, Nalan; Turkoglu, Vedat; Karahan, Fatih
Angiotensin-converting enzyme (ACE) was purified from human plasma by affinity chromatography. Effect of ethyl acetate, butanol and water extracts of Juniperus excelsa Bieb. (J. excelsa) fruits on purified ACE activity was investigated. ACE was purified 3659-fold with a specific activity of 1350 EU/mg protein from human plasma. The purity and molecular weight of ACE were determined by SDS-PAGE, and two bands 60kDa and 70kDa are seen on the gel. Ethyl acetate extract of J. excelsa fruits showed an activation effect on human plasma ACE activity. Butanol and water extracts of J. excelsa fruits showed an inhibition effect on ACE activity. IC50 values for butanol and water extracts of J. excelsa fruits were calculated to be 2.858mg/mL and 5.790mg/mL, respectively. Lisinopril was used to be reference inhibitor. Type of inhibition for all inhibitors was designated as non-competitive. IC50 value and K-i constant for lisinopril were determined to be 0.781nM and 0.662nM, respectively. These results show that butanol and water extracts of J. excelsa plant may have an ACE inhibitor potency.
In Vitro Effect of Oxidized and Reduced Glutathione Peptides on Angiotensin Converting Enzyme Purified From Human Plasma
(Elsevier Science Bv, 2019) Basi, Zehra; Turkoglu, Vedat
Angiotensin converting enzyme (ACE, peptidyldipeptidase A, EC 3.4.15.1) plays an important role in the regulation of blood pressure. In this study, ACE was purified from human plasma by affinity chromatography in single step. The enzyme purified in 5367-fold from human plasma and specific activity was found to be 1208 EU/mg protein. The purity and molecular weight of ACE were determined by SDS-PAGE, which indicated two bands at around 60 kDa and 70 kDa on the gel. Effect of oxidized glutathione (GSSG) peptide and reduced glutathione (GSH) peptide on purified ACE activity were also investigated in which lisinopril was used as reference inhibitor. GSSG showed activation effect on ACE activity whereas GSH provided inhibition effect. In the lights of activity (%) versus activator graph for GSSG and activity (%) versus inhibitor graphs for GSH and lisinopril; IC 50 values for GSH and lisinopril were determined to be 16.2 mu M and 0.781 nM, respectively. Type of inhibition for GSH and lisinopril from graph Lineweaver-Burk was found to be reversible non-competitive inhibition and K-i constants for GSH and lisinopril were calculated as 11.7 mu M and 0.662 nM, respectively.
Purification of Angiotensin-Converting Enzyme From Human Plasma and Investigation of the Effect of Some Active Ingredients Isolated From Nigella Sativa L. Extract on the Enzyme Activity
(Wiley, 2018) Basi, Zehra; Turkoglu, Vedat
In the present study, one-step purification of angiotensin-converting enzyme (ACE, peptidyldipeptidase A, EC 3.4.15.1), responsible for regulation of blood pressure, was achieved using affinity chromatography from human plasma. The enzyme was purified 12,860-fold with a specific activtiy of 5080 EU/mg protein. Optimum temperature and pH were determined for the enzyme as 35-40 degrees C and pH7.4-7.5, respectively. The purity of ACE was determined by SDS-PAGE and the enzyme showed two bands at 60 and 70kDa on the gel. The native molecular weight of ACE was found to be 260kDa by gel filtration chromatography, demonstrating that the enzyme has a heterodimeric structure. Natural fatty acids of Nigella sativa (Ranunculaceae) were isolated by means of column chromatography. The structures of these compounds were determined using NMR and GC-MS. The results showed that high concentrations of linoleic, oleic and palmitic acids were isolated from the plant. The effect of six fractions (Fr 1-6) on ACE activity was examined. Fraction 3 increased the ACE activity while the other fractions decreased the enzyme activity. The concentrations of the fractions inhibiting the half-maximum activity of the enzyme were calculated as 1.597mg/mL for Fr 1, 0.053mg/mL for Fr 2, 0.527mg/mL for Fr 4, 0.044mg/mL for Fr 5 and 0.136mg/mL for Fr 6 using a Lineweaver-Burk graph.