Conformational studies of the trypsin-aluminum(III) complex in solution by Raman and Fourier transform infrared attenuated total reflectance spectroscopy

This paper presents the results of Raman and Fourier transform IR studies investigating the interaction between AI(III) and trypsin, carried out in order to understand better how Al(III) can modify the biological properties of this proteolytic enzyme. The results indicate that Al(III) influences the secondary structure of trypsin. The trypsin-Al(III) complex in aqueous solution presents a molecular conformation similar to that of the trypsin-Al(III) crystal determined by x-ray diffraction analysis, but differs from the structure of both solid trypsin and trypsin in aqueous solution when; analyzed in the absence of AI(III). In particular, the interaction of the protein with aluminum in solution induces a decrease in the percentage of alpha-helix and an increase in the percentage of beta-sheet and random coil, Solid trypsin and trypsin in solution also displayed differences in secondary structure in the absence of Al(III).