Electron Conduction and Photocurrent Generation of a Light-Harvesting/Reaction Center Core Complex in Lipid Membrane Environments.
To reveal the structure-function relationship of membrane proteins, a membrane environment is often used to establish a suitable platform for assembly, functioning, and measurements. The control of the orientation of membrane proteins is the main challenge. In this study, the electron conductivity and photocurrent of a light-harvesting/reaction center core complex (LH1-RC) embedded in a lipid membrane were measured using conductive atomic force microscopy (C-AFM) and photoelectrochemical analysis. AFM topographs showed that LH1-RC molecules were well-orientated, with their H-subunits toward the membrane surface. Rectified conductivity was observed in LH1-RC under precise control of the applied force on the probe electrode (<600 pN). LH1-RC embedded in a membrane generated photocurrent upon irradiation when assembled on an electrode. The observed action spectrum was consistent with the absorption spectrum of LH1-RC. The control of the orientation of LH1-RC by lipid membranes provided well-defined conductivity and photocurrent.
†Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan.
Ayumi
A
Sumino
†Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan.|‡PRESTO/JST, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan.
Takehisa
T
Dewa
†Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan.
Nobuaki
N
Sasaki
†Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan.
Masaharu
M
Kondo
†Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan.
Mamoru
M
Nango
atomic force microscopy; conductive atomic force microscopy; light-harvesting/reaction center complex (LH1-RC complex); lipid membrane; photocurrent generation