Spin state transitions in Langmuir-Blodgett films of recombinant cytochrome P450scc and adrenodoxin

Langmuir-Blodgett (LB) films of recombinant cytochrome P450scc, of P450scc-adrenodoxin (Adx) complex and alternated layers of Adx and P450scc have been obtained. Spectral properties of these proteins in thin films were investigated by UV-Vis absorption spectroscopy. It has been found that cytochrome P450scc exists in LB films only in low-spin state while before the deposition it was in high-spin state. The data suggest that transferring the hemoprotein or its complex with redox partner results in the modification of the spin state by a conformational transition. In order to investigate further the P450scc and Adx interaction, the mass density of the films formed from these molecules has been studied by nanogravimetric measurements. Comparative study between nanogravimetric and spectral characterisation was performed. The results indicate that the protein-protein interaction is disrupted, when the complex is organised in thin film. (C) 2002 Elsevier Science B.V. All rights reserved.