815 cd spectrometer

Circular dichroism (CD) measurements were performed on a JASCO 815 CD spectrometer (Tokyo, Japan), using the Jasco software. Far UV-CD spectra were collected between 180–250 nm at 37°C. Measurements were recorded at 50 nm/min with a 1 nm bandwidth and a 2s response time, averaging 3 accumulation scans per measurement. All spectra were background subtracted, and smoothed with the default algorithm in the Jasco software. Experiments were performed in triplicate.

The Circular dichroism (CD) spectra of our samples in a standard 1 cm x 1 cm cuvette was recorded from 163 to 700 nm using a Jasco815 CD Spectrometer. Polymer solutions (0.25–2.0 mg/mL in aqueous media) in the absence and presence of TA (5 mg/mL) were prepared and incubated at room temperature before CD measurement at 25 °C. Background spectra of the water were acquired and then subtracted from the sample spectra and smoothed before plotting.

CD studies were done using a Jasco 815 CD spectrometer at 25°C with a cuvette of 1 mm path length and a total volume of 300 μL. Titration studies with either L-CSNO or D-CSNO were carried out with different molar ratios by repeatedly titrating ligand into the cuvette. For each sample, a spectrum ranging from 190 nm to 260 nm was collected with 1 nm intervals in 3 passes, the average of the 3 passes being used. Protein sample concentration at the beginning of the measurement was 5 μM and after the final addition of ligand 3.97 μM. The molar excess of ligand to protein ranged from a 10:1 to 112:1 ratio. A buffer baseline was subtracted from each of the samples. The molar ellipticity was calculated based on a molecular weight of 18.5 kDa and the corresponding protein concentration for each sample. For thermal stability in the presence and absence of L-CSNO or D-CSNO, measurements were carried out at 222 nm to observe α-helix unfolding upon heat treatment of the sample. The temperature was raised at 0.1°C intervals starting at 25°C to 100°C, with ramp temperature of 1°C per minute.