Immobilization of Porphyrin Derivatives with a Defined Distance and Orientation onto a Gold Electrode Using Synthetic Light-Harvesting α-Helix Hydrophobic Polypeptides

Abstract

Molecular assembly of Zn-porphyrin pigments on a gold electrode using synthetic 1α-helix hydrophobic polypeptides which have similar amino acid sequences to the hydrophobic core in the native photosynthetic light-harvesting (LH) 1-β polypeptide from Rhodobacter sphaeroides has been achieved. This method is clearly successful in allowing assembly of porphyrins together with LH1 type functional complexes with a defined distance and orientation on the electrode. In this case, the photocurrent direction and the distance of electron transfer of pigments could be controlled by these synthetic LH1 model polypeptides. This method will be useful for the self-assembly of these pigment and protein complexes in order to study the energy transfer and electron transfer reactions between individual pigments in the supramolecular complexes on the electrode, as well as to provide insight into the effect of the distance and orientation of pigments and the effect of the structure of 1α-helix hydrophobic polypeptide on the energy transfer and electron transfer reactions.