It is a fast, simple, and accurate method for studying protein conformation in dilute solutions.
If the wavelength λ of plane polarized light of different wavelengths is used as the abscissa, and the difference in absorption coefficient Δε = εL-εR is plotted as the ordinate, the resulting spectrum is the circular dichroism spectrum, or CD for short.
If a chiral compound absorbs in the ultraviolet-visible region, a characteristic circular dichroism spectrum can be obtained.
Circular dichroism and spin spectra are measured in the ultraviolet-visible region, the purpose of which is to infer the configuration and conformation of organic compounds Sample requirementsThe sample must maintain a certain purity without impurities that absorb light, and the solvent must not absorb interference at the measurement wavelength; the sample can be completely dissolved in the solvent to form a uniform and transparent solution.Control of nitrogen flowBuffer and solvent requirements and pool selection: buffer and solvent should be separately checked before preparing the solution to see if there is absorption interference in the measurement wavelength range, to see if precipitation and colloid are formed; in protein measurement, often Choose a phosphate system with excellent transparency as a buffer system.4 Sample concentration and pool selectionDifferent samples have different circular dichroism spectrum ranges, and different requirements for the selection of the size (light path) and concentration of the pool.
When the absorbance of the sample is high but the CD signal is weak, on the one hand, try to ensure that the concentration required for measuring the CD peak is sufficient, and on the other hand, set a wider slit.
However, special care should be taken at this time, because the sample may have some artifacts caused by fluorescence or stray light when the absorbance is too high (A> 2).
