Structure and antibacterial activity relationships of native and amyloid fibril lysozyme loaded on layered double hydroxide.

Lysozyme from hen egg white is composed by a unique linear chain of 129 amino acids. It is known to inhibit Gram positive bacteria and to form amyloid fibrils at low pH, under 75°C. This work investigates the effect of the fibrillation and/or adsorption onto a layered double hydroxide material on the antibacterial properties of lysozyme. The kinetics of adsorption follows a behavior of pseudo second order model. The X-ray diffraction and the Fourier transform infrared spectroscopy highlight that adsorption occurs only on the external surface of the material. Interestingly, the amyloid fibrils of lysozyme retain their antibacterial properties when they are adsorbed on the layered double hydroxide; even if their activity is lowered, the active site of the enzyme is not fully denatured and is still accessible. This is confirmed by the study of the tryptophan using time-resolved fluorescence spectroscopy.