Tunneling spectroscopic study of hydrogenase Langmuir–Blodgett film

Abstract

Hydrogenase Langmuir–Blodgett films from Thiocapsa roseopersicina were prepared on gold-coated mica substrates using 20 mer of poly-l-lysine, which stabilizes the enzyme and improves the protein transfer. Scanning tunneling microscopy and intermittent contact mode atomic force microscopy were used to observe the films and to determine that the single hydrogenase–hexagonal complex was laid horizontally to the gold surface. Tunneling spectroscopy of the hydrogenase complex demonstrated the diodelike current-voltage characteristics. The rectification of the tunneling current might be ascribed to the alignment of cofactors, a nickel atom and iron sulfur clusters of the hydrogenase.