T90 uv vis spectrophotometer

The activities of the following enzymes were investigated in this study: dehydrogenase (EC 1.1.1.1), urease (EC 3.5.1.5), and phosphatase (EC 3.1.3.2) using the spectrophotometric method. When determining dehydrogenase activity (DA), the method described by Schinner and coworkers was used [34 ]. In the case of the urease activity (UA), the method proposed by Alef and Nannipieri was considered, [35 ] and when investigating the phosphatase activity (PhA), the method exposed by Dick was used [36 ]. Details regarding the implementation of these methods were also presented in one of our previous studies regarding the assessment of the effects of the herbicide S-metolachlor on the activity of soil enzymes [37 (link)]. Determination of each enzymatic activity was performed every 7 days during a 28-day incubation period under laboratory conditions of the soil sown with wheat and barley seeds treated with TTZ. All measurements of enzymatic activities were performed using a T90 UV/Vis spectrophotometer (PG Instruments, England). For each soil sampling, the investigation was carried out in triplicate for each experimental variant by the same researcher on the same day.

The aggregation of insulin (0.5 mg/mL) was induced in the presence of 20 mM dithiothreitol (DTT) in phosphate buffer (50 mM, pH 7.2) [37 (link)]. The kinetic of aggregation was assessed at 40°C for 20 min by recording the optical density at 360 nm, using a T90⁺ UV-Vis spectrophotometer (PG Instruments) which equipped with Peltier temperature controller. Also, formation of amyloid fibril was monitored by ThT fluorescence analysis [38 (link)]. Fibril formation was initiated by incubation of insulin (2 mg/mL) in 20% acetic acid pH 2.0, containing 150 mM NaCl for 5 h, at 60°C [39 (link), 40 (link)]. At the end of incubation, 10 μM ThT was added to the protein solution and fluorescence measurement was done using an excitation wavelength at 450 nm [30 (link)]. The excitation and emission slits were 5 and 10, respectively.

UV–Vis Analysis: The UV-Vis spectra were obtained using a T90+ UV-Vis spectrophotometer (PG Instruments, UK) with a double beam in the photometric range of 190–900 nm. All absorbance measurements were taken in a 10 mm UV/Vis spectroscopy cell at room temperature, using ethanol as a blank.