Cary 50 bio spectrophotometer

The simplified DPPH assay for wine and wine by-products [45 (link)] was used to determine the antioxidant activity of thinned grapes, and the results were obtained according to simplified assay conditions. Measurements were made on three aliquots of each sample after 4 h at 515 nm in a Cary 50 Bio spectrophotometer (Varian, Australia). The results are expressed as EC₂₀ (the amount of sample necessary to decrease the initial DPPH concentration by 20%).

An osmotic fragility test was performed on freshly prepared RBCs (untreated and treated with β-Crt) following a classical procedure [25 (link)] with some modifications. Each sample (i–v) was equally divided and added to a series of 30 hypotonic solutions with a NaCl content ranging from 0.9% to 0%, incubated for 10 min at 4 °C, and centrifuged as described above. Absorption spectra of the collected supernatants were recorded in the range of 280–700 nm on a Cary 50 Bio-spectrophotometer (Varian). The haemolysis rate was determined as described previously [26 (link)]. The spectra in the range of 460–700 nm were analysed with OriginPro 2019b (OriginLab) using a combination of exponential and Gaussian functions to calculate the area under the spectrum, with the maximum at 577 nm (indicator of the amount of released Hb). The normalised haemolysis curves, as a function of NaCl concentration, are of a sigmoidal character. They were fitted using a basic Boltzmann function.

The pigment extraction was performed in 2 technical replicates according to Zavrel et al. (2015) (link), under low light conditions. Frozen samples from the bisabolene production experiments performed in the MC1000 multicultivators were thawed on ice, resuspended in 1 ​mL MeOH 100% (Alpha Aeser) and incubated for 1 ​h at 4 ​°C, protected from the light. The samples were then centrifuged for 10 ​min at 15,000×g and at 4 ​°C, and the supernatant was used for the absorption spectrum measurements in the 400–750 ​nm range. The spectra were obtained in a Varian Cary 50 BIO spectrophotometer, using methanol as blank. Chlorophyll a (Chl a) and carotenoids (Car) were quantified using the following equations: $$\left[Chl\text{a}\right]=12.9447x\left(Ab{s}_{665nm}-Ab{s}_{720nm}\right)\mu g{\text{mL}}^{-1}$$ $$\left[Car\right]=\frac{1000x\left(Ab{s}_{470nm}-Ab{s}_{720nm}\right)-2.86x\left[Chla\right]}{221}\mu g{\text{mL}}^{-1}$$

A 1000 ppm concentration of the encapsulated system was analyzed by UV-Vis spectroscopy (Varian Cary 50 BIO spectrophotometer). Successive spectra were acquired at different time intervals and the variation in the absorbance bands for annonacin (4) was studied. Scans from 200 to 600 nm were recorded every 30 s for the first 10 min, then a spectrum was acquired every minute up to 30 min and thereafter a spectrum every 15 min up to 24 h. Each experiment was carried out at 36 °C in saline buffer at pH 7.4, in the absence of light and with stirring, to simulate the conditions of a living organism.

Enzymatic cluster formation was achieved under strict anaerobic conditions in a Belle chamber kept under nitrogen atmosphere. The reaction was followed by absorbance spectroscopy using a Cary 50 Bio Spectrophotometer (Varian). Absorbance variations at 458 or 406 nm were measured as a function of time. A solution of 50 μM of apoFdx or 35 μM aconitase was incubated in sealed cuvettes typically using 3 mM DTT, IscU, HscA, HscB, 1 μM IscS, and 25 μM Fe(NH₄)₂(SO₄)₂ for 30 min in 20 mM Tris-HCl pH 8 and 150 mM NaCl. The reaction was initiated by adding 250 μM of the substrate L-cysteine and when specified 150 μM ATP. Each experiment was repeated at least 3 times on different batches of proteins and by two different researchers. To simplify the analysis, we took the initial slopes of the curves (absorbance vs. time) to qualitatively compare the time courses although some curves have a lag phase which likely reflects diffusion of the components.

UV–vis absorption spectra were collected on a Varian Cary 50 Bio spectrophotometer. Emission spectra were obtained on a PerkinElmer LS55 spectrophotometer at room temperature. Spectrophotometric grade solvents and quartz cuvettes (1 cm path length) were used. Relative fluorescence quantum yields (Φ_f) were calculated using rhodamine 6G (Φ_f = 0.86 in methanol) as the reference using the following equation: Φ_x = Φ_st × Grad_x/Grad_st × (η _x/η _st)², where Φ_X and Φ_ST are the quantum yields of the sample and standard, Grad_X and Grad_ST are the gradients from the plot of integrated fluorescence intensity vs. absorbance, and η represents the refractive index of the solvent (x is for the sample and st standard).