The electron conduction of photosynthetic protein complexes embedded in a membrane

Abstract

The conductivity of two photosynthetic protein^pig-ment complexes, a light harvesting 2 complex and a reaction center, was measured with an atomic force microscope capable of performing electrical measurements. Current^voltage measurements were performed on complexes embedded in their natural environment. Embedding the complexes in lipid bilayers made it possible to discuss the di¡erent conduction behaviors of the two complexes in light of their atomic structure.

Electron tunneling properties of outer-membrane decaheme cytochromes from Shewanella oneidensis

“…7). This rectifying behavior is a phenomenon that has been observed by STM elsewhere, for example, on copper-phthalocyanine molecules (Pomerantz et al, 1992) as well as on photosynthetic proteins (Stamouli et al, 2004). The I(V) behavior on the unactivated OGP overlayer is very similar to the I(V) behavior of the OGP-only film.…”

RETRACTED: Monolayers of pigment-protein complexes on a bare gold electrode: Orientation controlled deposition and comparison of electron transfer rate for two configurations

“…RC-LH1 complex has two types of co-factors; the central part (RC complex) has a dimer of bacteriochlorophyll and two symmetric branches of co-factors, each branch containing bacteriochlorophyll, a bacteriopheophytin and quinone. The RC complex reported to have diode like I-V characteristics (Lee et al, 1997;Mikayama et al, 2009Mikayama et al, , 2006Reiss et al, 2007;Stamouli et al, 2004). The peripheral part expected to have symmetric I-V response because it has similar architecture of co-factors to that of light harvesting 2 (LH2) complexes and LH2 complexes exhibit symmetric I-V response across V¼0 (Stamouli et al, 2004).…”

“…The RC complex reported to have diode like I-V characteristics (Lee et al, 1997;Mikayama et al, 2009Mikayama et al, , 2006Reiss et al, 2007;Stamouli et al, 2004). The peripheral part expected to have symmetric I-V response because it has similar architecture of co-factors to that of light harvesting 2 (LH2) complexes and LH2 complexes exhibit symmetric I-V response across V¼0 (Stamouli et al, 2004). The symmetric behavior of the I-V curves is attributed to the presence of carotenoid molecules, which act as molecular wires spanning the LH2 complex and they are capable of efficient electron transfer (Stamouli et al, 2004;Sumino et al, 2013).…”

Photocurrent of a single photosynthetic protein

“…4a, inset). Nonlinear characteristics have been reported both for transport across single reaction centres without laser excitation 11,20,21 and for corresponding photoconductance-voltage characteristics 22,23 .…”