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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, Ki constants of methidathion, cypermethrin, and deltamethrin were to be 3.294 ± 0.215, 0.718 ± 0.095, and 0.084 ± 0.009 mM respectively. The IC50 value were estimated as 9.95 × 10(-5) ± 0.1844 × 10(-5) mM for methidathion, 1.01 × 10(-4) ± 0.01413 × 10(-4) mM for cypermethrin, and 4.43 × 10(-6) ± 0.05653 × 10(-6) mM for deltamethrin. In conclusion, deltamethrin inhibits the enzyme activity more than methidathion and cypermethrin.

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°C and pH 7.4-7.5, respectively. The purity of ACE was determined by SDS-PAGE and the enzyme showed two bands at 60 and 70 kDa on the gel. The native molecular weight of ACE was found to be 260 kDa 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 1.597 mg/mL for Fr 1, 0.053 mg/mL for Fr 2, 0.527 mg/mL for Fr 4, 0.044 mg/mL for Fr 5 and 0.136 mg/mL for Fr 6 using a Lineweaver-Burk graph.

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 borondoped 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 μg mL À 1 (1.57 × 10 À 7 À 1.25 × 10 À 5 mol L À 1), with a detection limit of 0.013 μg mL À 1 (4.07 × 10 À 8 mol L À 1) by using squarewave adsorptive stripping voltammetry (SW-AdSV). The feasibility of the developed approach for the quantification of NFX in urine samples was tested.

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