Circular Dichroism

The core has a JASCO J-1500 circular dichroism spectropolarimeter.  The spectra provide information about protein structure, and  changes caused by temperature or solvents.

JASCO J-1500 circular dichroism instrument

Common experiments are observing changes in helical structure caused by changes in the solution or protein sequences, and observing changes in melting temperature caused by changes in solvent, stabilizing molecules, changes to the protein sequence. Several programs estimate the amount of helix, sheet and coil in a protein, with estimates dependent on the program used and the wavelength range used.

The instrument is user operated with a usage fee to cover the cost of high purity nitrogen and other supplies and maintenance. The core can give introductory training to new users. Each laboratory has an account on the computer which runs the instrument.

The Core has cells with path lengths of 0.1, 1, 2, 5, 10 mm. Phosphate buffer (without salt) gives the best wavelength range for taking spectra. There is a microcell which can take spectra on 10 µL of sample, but there is no temperature control for this cell which does not give data at short wavelengths and has a reduced range of concentrations it can read compared to a standard cell.

Sign up using iLab at

The program for the instrument can convert data to text files which can be opened in Microsoft Excel or other programs. There are programs to analyze structure on the computer. Most users transfer data from the computer with a USB flash drive. Many users convert the data files to an Excel compatible format. The instrument is in room 1074, Pinn Hall. Contact John Shannon ph. 434.243.9399