Cary 50 uv vis spectrometer

Room temperature static absorption spectra of methylcyclohexane solutions were collected using a Cary 50 UV–Vis spectrometer. Temperature-dependent measurements were made on solid films drop-cast from methylcyclohexane on to sapphire windows using a deuterium halogen lamp focused through the samples mounted on sapphire in a nitrogen-cooled cryostat and detected using an Ocean Optics spectrometer. Room temperature solution NIR measurements were performed using a Nicolet 6700 FT-IR (Fourier transform infrared) with an InGaAs detector with samples dispersed in carbon tetrachloride in quartz cuvettes.

Heme (25 μM) 50 μM NO, and 50 μM GSH were reacted for 30 minutes in the presence of red cell membrane ghosts under anaerobic conditions. The sample was incubated for another 30 minutes at 37°C after adding 75 μM albumin. After the incubation, the sample was scanned for absorption in the Cary 50 UV-Vis spectrometer. The sample was subsequently spun at 30,000 g for two hours in a Sorvall^R RC-5B ultracentrifuge and the absorption spectrum of the supernatant was measured.

p-Nitrosodimethylaniline (RNO) and imidazole has been reported for singlet oxygen detection.^{20–22 (link)} TiO₂-P25, TiO₂-P25-M, G, 1 : 3-M, 1 : 1-M, 3 : 1-M, 1 : 3-I, 1 : 1-I or 3 : 1-I at 300 mg L⁻¹ were suspended in a solution containing RNO (Sigma Aldrich) 45 μM and imidazole (Sigma Aldrich) 8 mM. The experiments were performed under UV or visible light. Aliquots were taken during 24 min and centrifuged at 12 000 rpm for 15 min. The RNO concentration was determined at 440 nm in a Varian Cary 50 UV-Vis spectrometer. Negative controls were made without material.

Protein pellets were resuspended and solubilized with rehydration buffer containing 7 M urea, 2 M thiourea, 4% CHAPS, and 0.002% bromophenol blue. Protein concentration was determined using the 2D Quant Kit (GE Healthcare, Stockholm, Sweden), following manufacturer’s protocol. A standard curve was obtained using 2 mg/ml Bovine serum albumin (BSA) stock solution. 500 µl precipitant was inserted into each tube, vortexed and incubated at ambient temperature for 2–3 min, then 500 µl co-precipitant was added. Tubes were then vortexed and centrifuged for 5 min at 10 000 x g and supernatant discarded. The tubes were centrifuged again. The residual supernatant was decanted. Copper solution (100 µl) and distilled water (400 µl) were added to each tube, and precipitated protein was dissolved by vortexing. The working reagent (1 ml) was added to each tube and mixed by inversion instantaneously. Absorbance was measured using Cary^®50 UV-Vis spectrometer at 480 nm (Varian Inc., Palo Alto, CA, USA).

UV-Vis spectra of Ga(NO₃)₃, CeCl₃, and (NH₄)₂Ce(NO₃)₆ were recorded in 50 mM sodium acetate buffer pH 5.5 in a 1 mL quartz cuvette with an optical path of 1 cm at room temperature on a Varian Cary 50 UV-Vis spectrometer at a scan speed setting “slow”. The concentrations of Ce⁴⁺ and Ga³⁺ were 0.5 mM and the concentration of Ce³⁺ was 0.05 mM. The spectra were recorded in the presence and absence of Z-Phe-Arg-AMC (benzyloxycarbonyl-Phe-Arg-7-amido-4methylcoumarin), one of the substrates used in kinetic measurements. The final concentration of the substrate was 5 µM. Background spectra of buffer alone were recorded separately and subtracted automatically from the samples.