Why use synchrotron radiation for CD?
SR provides inherently linearly polarised light, at higher photon fluxes than conventional sources, particularly at short wavelengths, with the following advantages: • Spectra can be collected to a lower wavelength limit, giving more precise secondary structure analysis. As no polariser is required, the limit extends to the cut-off of the PEM (usually 120-130 nm), allowing the collection of data from chromophores that report on the structure of e.g. carbohydrates. • Collection times for spectra can be considerably shorter than with conventional instruments, with much higher signal-to-noise. • Stopped-flow measurements require fewer combined shots to provide good data. • Stopped-flow measurements can be made over a wide wavelength range, allowing the collection of time-resolved CD spectra. These can be analysed to provide time-courses of the development of individual secondary structure types, suitable for kinetic analysis. The figures below show the advantages of SR as a light source f
