Circular dichroism (CD), is a commonly used quantitative technique for HOS which is most sensitive to alpha-helix content, providing information about both secondary and some tertiary structure. Fourier transform infrared spectroscopy (FT-IR) is an orthogonal quantitative method for secondary structure determination that is most sensitive to sheet content. Both techniques can be utilized to give an orthogonal assessment of structure, but should not be expected to provide the same result.