Cary 4000 uv vis spectrophotometer

Room-temperature absorption spectra were measured with a Varian Cary 4000 UV-Vis-spectrophotometer. The Circular-dichroism (CD) spectra were recorded using a Chirascan-Plus spectropolarimeter (Applied Photophysics) at 20 °C. The OD of the samples was 0.8–1/cm at the maximum of the Qy band. All measurements were performed in the same buffers used for the sucrose gradients.

Absorption spectra were measured at room temperature with a Varian Cary 4000 UV-Vis-spectrophotometer. CD spectra were recorded using a Chirascan-Plus spectropolarimeter (Applied Photophysics) at 20°C. The OD of the samples was 0.8–1/cm at the maximum of the Qy region.

Absorption
spectra were recorded on a Varian Cary 4000 UV–vis spectrophotometer.
For measurements at 77 K, a home-built liquid-nitrogen-cooled device
was used. The samples were supplemented with 70% (v/v) of glycerol
to prevent the formation of ice crystals. Emission spectra were recorded
on a HORIBA JobinYvon-Spex Fluorolog 3.22 spectrofluorimeter at an
optical density of <0.05 cm^–1 at the Q_y maximum. Circular dichroism (CD) spectra were measured
with a Chirascan CD spectrophotometer at 10 °C.

UV absorbance measurements were conducted on a Varian Cary 4000 UV/vis spectrophotometer. Gels containing radioactively labeled samples with [γ-³²P]ATP were exposed to a phosphor imaging plate and scanned with a GE Healthcare FLA 7000 laser scanner.

The stability of DNA bulges in the presence of the helicates was monitored by measuring the absorbance at 260 nm (1 nm bandwidth, average time: 10 s, heating rate 0.4 °C/min) as a function of temperature. The experiment was run simultaneously on six masked 1 cm pathlength microcuvettes of 0.2 mL volume using a Peltier controlled 6-sample cell-changer in a Varian Cary 4000 UV/vis spectrophotometer. Melting temperature (T_m) was calculated within the thermal heating program by applying a first derivative calculation. The T_m values could be determined with an accuracy of ±0.5 °C. Each DNA melting experiment was carried out at least three times and the T_m values represent the mean. The concentration of oligoribonucleotides was 3 μM per strand. The buffer conditions were sodium phosphate buffer (10 mM, pH 7.0) and 0.5 mM EDTA.

All reagents were purchased from Sigma-Aldrich (St. Louis, MO, USA), and they have been used without any further purification, if not specified otherwise. UV–vis spectra were recorded on a Varian Cary 4000 UV–vis spectrophotometer (Varian, Palo Alto, CA, USA) using a 1.0 cm cell. Fluorescence spectra were registered on a Jasco FP750 spectrofluorometer (Jasco, Easton, MD, USA) using a 1.0 cm cell. NMR spectra were recorded on Varian Inova 400 and/or Varian Mercury plus 400 instruments. Chemical shifts were reported in parts per million (ppm) relative to the residual solvent peak, rounded to the nearest 0.01 for proton and 0.1 for carbon reference: CHCl₃ [¹H: 7.26 ppm, ¹³C: 77.0 ppm]. Coupling constants J were reported in Hz to the nearest 0.01 Hz. Peak multiplicity was indicated as follows: s (singlet), d (doublet), t (triplet), q (quartet), m (multiplet), and br (broad signal). ESI-MS was recorded on the LC-MS LCQ Fleet ThermoFisher Scientific (Waltham, MA, USA). Centrifugations were performed on an AFI SIRENA centrifuge (AFI, Château-Gontier-sur-Mayenne, FR).

Room temperature absorption spectra were acquired on a Varian Cary 4000 UV-Vis spectrophotometer. Circular dichroism (CD) spectra were recorded on a Chirascan CD Spectrophotometer (Applied Photophysics), at 10°C. Time-resolved fluorescence was recorded via Time-Correlated Single Photon Counting on a FluoTime 200 from PicoQuant, at 10°C. Excitation was centered at 470 nm (Chl b and astaxanthin region), with an average power of ≈100 μW and a repetition rate of 10 MHz. Signal was accumulated until a maximum of 20 thousand counts at the peak channel, over channels separated by 8 ps. The Instrument Response Function was estimated via the measured decay of a pinacyanol iodide, whose lifetime is ≈6 ps^{52 (link)}.