J 715 circular dichroism spectrometer

Optical rotatory dispersions were acquired using a JASCO P-2000 spectrometer. Optical rotations were obtained on an Optical Activity AA-55 series polarimeter. UV data were performed on a Perkin-Elmer model 241 spectrophotometer in MeOH. Electronic circular dichroism spectra were measured using a JASCO J-715 circular dichroism spectrometer. IR spectra were determined using KBr pellets with a Nicolet NEXUS 470 spectrophotometer. Vibrational circular dichroism spectra were taken on a BioTools ChiralIR-2X spectrophotometer. 1D and 2D NMR data (600 MHz for ¹H and 150 MHz for ¹³C) were acquired on Bruker Avance-III 600 MHz NMR spectrometer with TMS as an internal standard. High-resolution mass data were obtained from a Thermo Scientific LTQ Orbitrap XL spectrometer. HPLC analysis and semi-preparation was performed on a Shimadzu LC-20AT system with a SPD-M20A photodiode array detector, using a Waters RP-18 (XBridge OBD, 5 μm, 10 × 250 mm) and a Waters normal phase (Viridis^TM Silica 2-Ethylpyridine, 5 μm, 10 × 250 mm) columns. Column chromatography was performed on Silica gel 200–300 mesh (Qingdao Marine Chemical Factory), and Sephadex LH-20 (18–110 μm, Pharmacia Fine Chemical Co., Ltd., Sweden).

1 mg mL⁻¹ of protein was analysed using far UV spectra (190–270 nm) measured by a Jasco J715 Circular Dichroism Spectrometer (Jasco Inc.). Spectra were taken at 20 °C. 4 readings were taken for each measurement and averaged by the software provided.
For spectra analysis the following Eq. 1 was used. ${\left[\theta \right]}_{MRW=}\frac{\frac{MW}{\left(n-1\right)}\times \theta }{l\times c\times 10}$ where θ_MRW is the mean residue elipticity, MW is the molecular weight of the protein, n is the number of amino acids, θ is the degrees in elipticity, l is the path length and c is the concentration.