Fourier transform infrared attenuated total reflectance spectrometry of hemolymph and hemocyanin in water solutions.

Fourier transform infrared (FT-IR) spectrometry with attenuated total reflectance (ATR) was used for the determination of absorption and difference spectra of Rapana venosa hemolymph and of purified hemocyanin in solution or as lyophilized sample. In order to obtain a more detailed assignment of the protein spectra, the experiments were carried out both in water and in deuterium oxide solution. The results allowed to assign the protein spectra. The amide bands were used to determine quantitatively the amount of the different types of protein secondary structures. The analysis were carried out by using the spectral decomposition by Gaussian and Lorentzian functions, which permitted to obtain distinct peaks in the amide regions. Finally, by measuring the areas of these peaks, the distribution of the secondary ordered structures of R. venosa hemocyanin in solution and in solid was determined