Gel filtration chromatography, fluorescence spectrophotometry, differential scanning calorimetry (DSC) and Fourier transform infrared spectrophotometry (FT-IR) were used to investigate the interaction between polyvinyl alcohol (PVA) and lysozyme under physiological conditions. The results showed that lysozyme formed complex with PVA. During lysozyme interaction with PVA, emission fluorescence derived from tryptophan of lysozyme was partially quenched upon binding to PVA. However, microenvironment of tryptophan was not changed during the binding processs. The results of DSC showed that the interaction of PVA with lysozyme did not destroy advanced structures of lysozyme. Fourier transform infrared spectrometry was combined with resolution enhancement technique Fourier deconvolution and Gaussian curve-fitting procedures to quantitate the spectral information from the amide I bands of lysozyme within the freeze-dried mixture of PVA and lysozyme. The results showed that the interaction of PVA with lysozyme affected only the β-sheet content rather than α-helix , which was usually used as an indicator of the protein structural integrity in lyophilized state. Analysis of activity of the lysozyme showed that interaction of PVA with the lysozyme did not destroy the tertiary structure of the lysozyme.

Key words: polyvinyl alcohol, lysozyme, Fourier transform infrared spectrometry, gel chromatography, fluorescence spectrometry