Fig. 5

Second derivative of the amide I band, fitting results and corresponding residuals for a free β-gal in D₂O ([β-gal] = 150 µg mL⁻¹) and b β-gal adsorbed on a porous film of TiO₂ nanoparticles ([β-gal] = 150 µg mL⁻¹, [TiO₂] = 1.3 mg mL⁻¹, adsorption time: 8 h), background spectrum: TiO₂ film in contact with D₂O. The band parameters of the deconvoluted single components are listed in Table 1. c Graphical representation of the protein structure of β-gal retrieved from the Protein Databank (pdb entry: 1f4a) [45] with the α/β barrel carrying the active center of one of the four monomers (indicated by a black arrow) surrounded by four domains rich in β-sheet structures (marked by yellow arrows). α-helices and β-sheets of one monomer are highlighted in red and green, respectively