The structure of proteins in aqueous solutions: an assessment of triose phosphate isomerase structure by Fourier-transform infrared spectroscopy.

Recent resolution enhancement and curve-fitting techniques have been applied to infrared spectra from triose phosphate isomerase in aqueous solution, in order to obtain quantitative information on its secondary structure. From our results, 57% alpha-helix, 25% beta-parallel and 10% beta-turns are predicted, in close agreement with the X-ray crystallographic data. On the other hand, measurements of band intensities, both in original and deconvolved spectra are shown to be unreliable for the quantification of secondary structures. The presence of beta-edge structure interacting with the alpha-helical barrel is described and discussed.