Interaction of Lysozyme with Poly(L-lysine)/Hyaluronic Acid Multilayers: An ATR-FTIR Study

Polyelectrolyte multilayers (PEM) loaded with bioactive molecules such as proteins serve as excellent mimics of an extracellular matrix and may find applications in fields such as biomedicine and cell biology. A question which is crucial to the successful employment of PEMs is whether conformation and bioactivity of the loaded proteins is preserved. In this work, the polarized attenuated total reflection Fourier transform infrared (ATR-FTIR) technique is applied to investigate the conformation of the protein lysozyme (Lys) loaded into the poly(L-lysine)/hyaluronic acid (PLL/HA) multilayers. Spectra are taken from the protein in the PEMs coated onto an ATR crystal during protein adsorption and desorption. For comparison, a similar investigation is performed for the case of Lys in contact with the uncoated crystal. The study highlights the presence of both tightly and poorly bound Lys fractions in the PEM. These fractions differ in their conformation and release behavior from the PEM upon washing. Comparison of spectra recorded with different polarizations suggests preferential orientation of alpha helical structures, beta sheets and turns in the tightly bound Lys. In contrast, the poorly bound fraction shows isotropic orientation and its conformation is well preserved.

Automated summary

In this study, the conformation of the protein lysozyme (Lys) loaded into polyelectrolyte multilayers (PEMs) was investigated using polarized attenuated total reflection Fourier transform infrared (ATR-FTIR) technique. The results showed that Lys in the PEMs existed as tightly bound and poorly bound fractions, which differed in their conformation and release behavior. The tightly bound fraction exhibited preferential orientation of alpha helical structures, beta sheets, and turns.